This patchset converts NFS with fscache non-direct READ IO paths to
use the netfs API with a non-invasive approach. The existing NFS pgio
layer does not need extensive changes, and is the best way so far I've
found to address Trond's concerns about modifying the IO path [1] as
well as only enabling netfs when fscache is configured and enabled [2].
I have not attempted performance comparisions to address Chuck
Lever's concern [3] because we are not converting the non-fscache
enabled NFS IO paths to netfs.
The main patch to be reviewed is patch #3 which converts nfs_read_folio
and nfs_readahead.
Changes since v3
- PATCH2: Improve #ifdef readability; use VFS_I #define (Jeff Layton)
- PATCH3: Fix Aug 30 kernel test robot <[email protected]> compile warning due
to unusued 'sreq' variables in fscache.c (test build with W=1)
- PATCH3: Simplify nfs_netfs_init_request (Jeff Layton, Matt Wilcox)
The patches are fairly stable as evidenced with xfstests generic with
various servers: hammerspace w/NFS4.2+fscache,
NetApp(ontap9) NFSv4.1+fscache (other tests in progress)
The known issues are as follows:
No major issues outstanding - the data corruption is unrelated to this
patchset. The known issues are as follows:
1. Unit test setting rsize < readahead does not properly read from
fscache but re-reads data from the NFS server
* This will be fixed with another linux-cachefs [4] patch to resolve
"Stop read optimisation when folio removed from pagecache"
2. "Cache volume key already in use" after xfstest runs
* xfstests (hammerspace with vers=4.2,fsc) shows the following on the
console after some tests:
"NFS: Cache volume key already in use (nfs,4.1,2,c50,cfe0100a,3,,,8000,100000,100000,bb8,ea60,7530,ea60,1)"
* This may be fixed with another patch [4] that is in progress
3. (RESOLVED) Hang
4. (DEFERRED/UNRELATED) Data corruption seen with unit test where rsize < readahead
* Confirmed unrelated to this patchset
* Seen with vanilla 6.0-rc2 (did not occur on 5.19)
* Not 100% reproducible (maybe 75% of the time)
* NFS protocol version doesn't matter
* First page is always fine, next 3 pages are not
* Garbage data is coming over the wire from the NFS server
because the NFS server file is garbage (the dd of the file from
/tmp to NFS /mnt corrupts it).
mount -o vers=4.2,fsc,rsize=8192 127.0.0.1:/export /mnt
dd if=/dev/urandom of=/tmp/integrity-rsize-file1.bin bs=16k count=1
./nfs-readahead.sh set /mnt 16384
dd if=/tmp/integrity-rsize-file1.bin of=/mnt/integrity-rsize-file1.bin bs=16k count=1
echo 3 > /proc/sys/vm/drop_caches
md5sum /mnt/integrity-rsize-file1.bin /tmp/integrity-rsize-file1.bin
md5sums don't match, MD5_NFS = 00eaf1a5bc1b3dfd54711db551619afa != MD5_LOCAL = e8d835c83ba1f1264869dc40673fa20c
5. generic/127 triggers "Subreq overread" warning
* just hit one time; did not stop test
[ 4196.864176] run fstests generic/127 at 2022-08-31 17:29:38
[ 5608.997945] ------------[ cut here ]------------
[ 5609.000476] Subreq overread: R1c85d[0] 73728 > 70073 - 0
The patchset is based on 6.0-rc3 and has been pushed to github at:
https://github.com/DaveWysochanskiRH/kernel/commits/nfs-fscache-netfs
[1] https://lore.kernel.org/linux-nfs/[email protected]/
[2] https://lore.kernel.org/linux-nfs/[email protected]/
[3] https://marc.info/?l=linux-nfs&m=160597917525083&w=4
[4] https://www.mail-archive.com/[email protected]/msg03043.html
[5] https://marc.info/?l=linux-nfs&m=165962662200679&w=4
Dave Wysochanski (3):
NFS: Rename readpage_async_filler to nfs_pageio_add_page
NFS: Add support for netfs in struct nfs_inode and Kconfig
NFS: Convert nfs_read_folio and nfs_readahead to netfs APIs
fs/nfs/Kconfig | 1 +
fs/nfs/delegation.c | 2 +-
fs/nfs/dir.c | 2 +-
fs/nfs/fscache.c | 191 ++++++++++++++++++---------------------
fs/nfs/fscache.h | 77 ++++++++--------
fs/nfs/inode.c | 8 +-
fs/nfs/internal.h | 10 +-
fs/nfs/pagelist.c | 14 +++
fs/nfs/pnfs.c | 12 +--
fs/nfs/read.c | 117 ++++++++----------------
fs/nfs/write.c | 2 +-
include/linux/nfs_fs.h | 19 +---
include/linux/nfs_page.h | 1 +
include/linux/nfs_xdr.h | 1 +
14 files changed, 210 insertions(+), 247 deletions(-)
--
2.31.1
Rename readpage_async_filler to nfs_pageio_add_page to
better reflect what this function does (add a page to
the nfs_pageio_descriptor), and simplify arguments to
this function by removing struct nfs_readdesc.
Signed-off-by: Dave Wysochanski <[email protected]>
---
fs/nfs/read.c | 60 +++++++++++++++++++++++++--------------------------
1 file changed, 30 insertions(+), 30 deletions(-)
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 8ae2c8d1219d..525e82ea9a9e 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -127,11 +127,6 @@ static void nfs_readpage_release(struct nfs_page *req, int error)
nfs_release_request(req);
}
-struct nfs_readdesc {
- struct nfs_pageio_descriptor pgio;
- struct nfs_open_context *ctx;
-};
-
static void nfs_page_group_set_uptodate(struct nfs_page *req)
{
if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
@@ -153,7 +148,8 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
/* note: regions of the page not covered by a
- * request are zeroed in readpage_async_filler */
+ * request are zeroed in nfs_pageio_add_page
+ */
if (bytes > hdr->good_bytes) {
/* nothing in this request was good, so zero
* the full extent of the request */
@@ -281,8 +277,10 @@ static void nfs_readpage_result(struct rpc_task *task,
nfs_readpage_retry(task, hdr);
}
-static int
-readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
+int
+nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
+ struct nfs_open_context *ctx,
+ struct page *page)
{
struct inode *inode = page_file_mapping(page)->host;
unsigned int rsize = NFS_SERVER(inode)->rsize;
@@ -302,15 +300,15 @@ readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
goto out_unlock;
}
- new = nfs_create_request(desc->ctx, page, 0, aligned_len);
+ new = nfs_create_request(ctx, page, 0, aligned_len);
if (IS_ERR(new))
goto out_error;
if (len < PAGE_SIZE)
zero_user_segment(page, len, PAGE_SIZE);
- if (!nfs_pageio_add_request(&desc->pgio, new)) {
+ if (!nfs_pageio_add_request(pgio, new)) {
nfs_list_remove_request(new);
- error = desc->pgio.pg_error;
+ error = pgio->pg_error;
nfs_readpage_release(new, error);
goto out;
}
@@ -332,7 +330,8 @@ readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
int nfs_read_folio(struct file *file, struct folio *folio)
{
struct page *page = &folio->page;
- struct nfs_readdesc desc;
+ struct nfs_pageio_descriptor pgio;
+ struct nfs_open_context *ctx;
struct inode *inode = page_file_mapping(page)->host;
int ret;
@@ -358,29 +357,29 @@ int nfs_read_folio(struct file *file, struct folio *folio)
if (file == NULL) {
ret = -EBADF;
- desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
- if (desc.ctx == NULL)
+ ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+ if (ctx == NULL)
goto out_unlock;
} else
- desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
+ ctx = get_nfs_open_context(nfs_file_open_context(file));
- xchg(&desc.ctx->error, 0);
- nfs_pageio_init_read(&desc.pgio, inode, false,
+ xchg(&ctx->error, 0);
+ nfs_pageio_init_read(&pgio, inode, false,
&nfs_async_read_completion_ops);
- ret = readpage_async_filler(&desc, page);
+ ret = nfs_pageio_add_page(&pgio, ctx, page);
if (ret)
goto out;
- nfs_pageio_complete_read(&desc.pgio);
- ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
+ nfs_pageio_complete_read(&pgio);
+ ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
if (!ret) {
ret = wait_on_page_locked_killable(page);
if (!PageUptodate(page) && !ret)
- ret = xchg(&desc.ctx->error, 0);
+ ret = xchg(&ctx->error, 0);
}
out:
- put_nfs_open_context(desc.ctx);
+ put_nfs_open_context(ctx);
trace_nfs_aop_readpage_done(inode, page, ret);
return ret;
out_unlock:
@@ -391,9 +390,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
void nfs_readahead(struct readahead_control *ractl)
{
+ struct nfs_pageio_descriptor pgio;
+ struct nfs_open_context *ctx;
unsigned int nr_pages = readahead_count(ractl);
struct file *file = ractl->file;
- struct nfs_readdesc desc;
struct inode *inode = ractl->mapping->host;
struct page *page;
int ret;
@@ -407,25 +407,25 @@ void nfs_readahead(struct readahead_control *ractl)
if (file == NULL) {
ret = -EBADF;
- desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
- if (desc.ctx == NULL)
+ ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+ if (ctx == NULL)
goto out;
} else
- desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
+ ctx = get_nfs_open_context(nfs_file_open_context(file));
- nfs_pageio_init_read(&desc.pgio, inode, false,
+ nfs_pageio_init_read(&pgio, inode, false,
&nfs_async_read_completion_ops);
while ((page = readahead_page(ractl)) != NULL) {
- ret = readpage_async_filler(&desc, page);
+ ret = nfs_pageio_add_page(&pgio, ctx, page);
put_page(page);
if (ret)
break;
}
- nfs_pageio_complete_read(&desc.pgio);
+ nfs_pageio_complete_read(&pgio);
- put_nfs_open_context(desc.ctx);
+ put_nfs_open_context(ctx);
out:
trace_nfs_aop_readahead_done(inode, nr_pages, ret);
}
--
2.31.1
As first steps for support of the netfs library when NFS_FSCACHE is
configured, add NETFS_SUPPORT to Kconfig and add the required netfs_inode
into struct nfs_inode.
Using netfs requires we move the VFS inode structure to be stored
inside struct netfs_inode, along with the fscache_cookie.
Thus, create a new helper, VFS_I(), which is defined
differently depending on whether NFS_FSCACHE is configured.
In addition, use the netfs_inode() and netfs_i_cookie() helpers,
and remove our own helper, nfs_i_fscache().
Later patches will convert NFS fscache to fully use netfs.
Link: https://lore.kernel.org/linux-nfs/[email protected]/
Signed-off-by: Dave Wysochanski <[email protected]>
---
fs/nfs/Kconfig | 1 +
fs/nfs/delegation.c | 2 +-
fs/nfs/dir.c | 2 +-
fs/nfs/fscache.c | 20 +++++++++-----------
fs/nfs/fscache.h | 15 ++++++---------
fs/nfs/inode.c | 6 +++---
fs/nfs/internal.h | 2 +-
fs/nfs/pnfs.c | 12 ++++++------
fs/nfs/write.c | 2 +-
include/linux/nfs_fs.h | 34 +++++++++++++++++++++++-----------
10 files changed, 52 insertions(+), 44 deletions(-)
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 14a72224b657..8fbb6caf3481 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -171,6 +171,7 @@ config ROOT_NFS
config NFS_FSCACHE
bool "Provide NFS client caching support"
depends on NFS_FS=m && FSCACHE || NFS_FS=y && FSCACHE=y
+ select NETFS_SUPPORT
help
Say Y here if you want NFS data to be cached locally on disc through
the general filesystem cache manager
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 5c97cad741a7..b5c492d40367 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -306,7 +306,7 @@ nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
}
spin_unlock(&delegation->lock);
if (ret)
- nfs_clear_verifier_delegated(&nfsi->vfs_inode);
+ nfs_clear_verifier_delegated(VFS_I(nfsi));
out:
return ret;
}
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 5d6c2ddc7ea6..b63c624cea6d 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2799,7 +2799,7 @@ nfs_do_access_cache_scan(unsigned int nr_to_scan)
if (nr_to_scan-- == 0)
break;
- inode = &nfsi->vfs_inode;
+ inode = VFS_I(nfsi);
spin_lock(&inode->i_lock);
if (list_empty(&nfsi->access_cache_entry_lru))
goto remove_lru_entry;
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index e861d7bae305..a6fc1c8b6644 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -163,13 +163,14 @@ void nfs_fscache_init_inode(struct inode *inode)
struct nfs_server *nfss = NFS_SERVER(inode);
struct nfs_inode *nfsi = NFS_I(inode);
- nfsi->fscache = NULL;
+ netfs_inode(inode)->cache = NULL;
if (!(nfss->fscache && S_ISREG(inode->i_mode)))
return;
nfs_fscache_update_auxdata(&auxdata, inode);
- nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
+ netfs_inode(inode)->cache = fscache_acquire_cookie(
+ nfss->fscache,
0,
nfsi->fh.data, /* index_key */
nfsi->fh.size,
@@ -183,11 +184,8 @@ void nfs_fscache_init_inode(struct inode *inode)
*/
void nfs_fscache_clear_inode(struct inode *inode)
{
- struct nfs_inode *nfsi = NFS_I(inode);
- struct fscache_cookie *cookie = nfs_i_fscache(inode);
-
- fscache_relinquish_cookie(cookie, false);
- nfsi->fscache = NULL;
+ fscache_relinquish_cookie(netfs_i_cookie(&NFS_I(inode)->netfs), false);
+ netfs_inode(inode)->cache = NULL;
}
/*
@@ -212,7 +210,7 @@ void nfs_fscache_clear_inode(struct inode *inode)
void nfs_fscache_open_file(struct inode *inode, struct file *filp)
{
struct nfs_fscache_inode_auxdata auxdata;
- struct fscache_cookie *cookie = nfs_i_fscache(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
bool open_for_write = inode_is_open_for_write(inode);
if (!fscache_cookie_valid(cookie))
@@ -230,7 +228,7 @@ EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
void nfs_fscache_release_file(struct inode *inode, struct file *filp)
{
struct nfs_fscache_inode_auxdata auxdata;
- struct fscache_cookie *cookie = nfs_i_fscache(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
loff_t i_size = i_size_read(inode);
nfs_fscache_update_auxdata(&auxdata, inode);
@@ -243,7 +241,7 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
static int fscache_fallback_read_page(struct inode *inode, struct page *page)
{
struct netfs_cache_resources cres;
- struct fscache_cookie *cookie = nfs_i_fscache(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
struct iov_iter iter;
struct bio_vec bvec[1];
int ret;
@@ -271,7 +269,7 @@ static int fscache_fallback_write_page(struct inode *inode, struct page *page,
bool no_space_allocated_yet)
{
struct netfs_cache_resources cres;
- struct fscache_cookie *cookie = nfs_i_fscache(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
struct iov_iter iter;
struct bio_vec bvec[1];
loff_t start = page_offset(page);
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 2a37af880978..38614ed8f951 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -54,7 +54,7 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
if (current_is_kswapd() || !(gfp & __GFP_FS))
return false;
folio_wait_fscache(folio);
- fscache_note_page_release(nfs_i_fscache(folio->mapping->host));
+ fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
nfs_inc_fscache_stats(folio->mapping->host,
NFSIOS_FSCACHE_PAGES_UNCACHED);
}
@@ -66,7 +66,7 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
*/
static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
{
- if (nfs_i_fscache(inode))
+ if (netfs_inode(inode)->cache)
return __nfs_fscache_read_page(inode, page);
return -ENOBUFS;
}
@@ -78,7 +78,7 @@ static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
static inline void nfs_fscache_write_page(struct inode *inode,
struct page *page)
{
- if (nfs_i_fscache(inode))
+ if (netfs_inode(inode)->cache)
__nfs_fscache_write_page(inode, page);
}
@@ -101,13 +101,10 @@ static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *
static inline void nfs_fscache_invalidate(struct inode *inode, int flags)
{
struct nfs_fscache_inode_auxdata auxdata;
- struct nfs_inode *nfsi = NFS_I(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
- if (nfsi->fscache) {
- nfs_fscache_update_auxdata(&auxdata, inode);
- fscache_invalidate(nfsi->fscache, &auxdata,
- i_size_read(inode), flags);
- }
+ nfs_fscache_update_auxdata(&auxdata, inode);
+ fscache_invalidate(cookie, &auxdata, i_size_read(inode), flags);
}
/*
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index bea7c005119c..aa2aec785ab5 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1411,7 +1411,7 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
static bool nfs_file_has_writers(struct nfs_inode *nfsi)
{
- struct inode *inode = &nfsi->vfs_inode;
+ struct inode *inode = VFS_I(nfsi);
if (!S_ISREG(inode->i_mode))
return false;
@@ -2249,7 +2249,7 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
#ifdef CONFIG_NFS_V4_2
nfsi->xattr_cache = NULL;
#endif
- return &nfsi->vfs_inode;
+ return VFS_I(nfsi);
}
EXPORT_SYMBOL_GPL(nfs_alloc_inode);
@@ -2273,7 +2273,7 @@ static void init_once(void *foo)
{
struct nfs_inode *nfsi = (struct nfs_inode *) foo;
- inode_init_once(&nfsi->vfs_inode);
+ inode_init_once(VFS_I(nfsi));
INIT_LIST_HEAD(&nfsi->open_files);
INIT_LIST_HEAD(&nfsi->access_cache_entry_lru);
INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 27c720d71b4e..273687082992 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -355,7 +355,7 @@ nfs4_label_copy(struct nfs4_label *dst, struct nfs4_label *src)
static inline void nfs_zap_label_cache_locked(struct nfs_inode *nfsi)
{
- if (nfs_server_capable(&nfsi->vfs_inode, NFS_CAP_SECURITY_LABEL))
+ if (nfs_server_capable(VFS_I(nfsi), NFS_CAP_SECURITY_LABEL))
nfsi->cache_validity |= NFS_INO_INVALID_LABEL;
}
#else
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 2613b7e36eb9..035bf2eac2cf 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -763,19 +763,19 @@ static struct pnfs_layout_hdr *__pnfs_destroy_layout(struct nfs_inode *nfsi)
struct pnfs_layout_hdr *lo;
LIST_HEAD(tmp_list);
- spin_lock(&nfsi->vfs_inode.i_lock);
+ spin_lock(&VFS_I(nfsi)->i_lock);
lo = nfsi->layout;
if (lo) {
pnfs_get_layout_hdr(lo);
pnfs_mark_layout_stateid_invalid(lo, &tmp_list);
pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
- spin_unlock(&nfsi->vfs_inode.i_lock);
+ spin_unlock(&VFS_I(nfsi)->i_lock);
pnfs_free_lseg_list(&tmp_list);
- nfs_commit_inode(&nfsi->vfs_inode, 0);
+ nfs_commit_inode(VFS_I(nfsi), 0);
pnfs_put_layout_hdr(lo);
} else
- spin_unlock(&nfsi->vfs_inode.i_lock);
+ spin_unlock(&VFS_I(nfsi)->i_lock);
return lo;
}
@@ -790,9 +790,9 @@ static bool pnfs_layout_removed(struct nfs_inode *nfsi,
{
bool ret;
- spin_lock(&nfsi->vfs_inode.i_lock);
+ spin_lock(&VFS_I(nfsi)->i_lock);
ret = nfsi->layout != lo;
- spin_unlock(&nfsi->vfs_inode.i_lock);
+ spin_unlock(&VFS_I(nfsi)->i_lock);
return ret;
}
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 1843fa235d9b..d84121799a7a 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -828,7 +828,7 @@ nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
{
struct nfs_page *freq, *t;
struct nfs_commit_info cinfo;
- struct inode *inode = &nfsi->vfs_inode;
+ struct inode *inode = VFS_I(nfsi);
nfs_init_cinfo_from_inode(&cinfo, inode);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 7931fa472561..a1c402e26abf 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -31,6 +31,10 @@
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/clnt.h>
+#ifdef CONFIG_NFS_FSCACHE
+#include <linux/netfs.h>
+#endif
+
#include <linux/nfs.h>
#include <linux/nfs2.h>
#include <linux/nfs3.h>
@@ -204,9 +208,11 @@ struct nfs_inode {
__u64 write_io;
__u64 read_io;
#ifdef CONFIG_NFS_FSCACHE
- struct fscache_cookie *fscache;
-#endif
+ struct netfs_inode netfs; /* netfs context and VFS inode */
+#else
struct inode vfs_inode;
+#endif
+
#ifdef CONFIG_NFS_V4_2
struct nfs4_xattr_cache *xattr_cache;
@@ -281,10 +287,25 @@ struct nfs4_copy_state {
#define NFS_INO_LAYOUTSTATS (11) /* layoutstats inflight */
#define NFS_INO_ODIRECT (12) /* I/O setting is O_DIRECT */
+#ifdef CONFIG_NFS_FSCACHE
+static inline struct inode *VFS_I(struct nfs_inode *nfsi)
+{
+ return &nfsi->netfs.inode;
+}
+static inline struct nfs_inode *NFS_I(const struct inode *inode)
+{
+ return container_of(inode, struct nfs_inode, netfs.inode);
+}
+#else
+static inline struct inode *VFS_I(struct nfs_inode *nfsi)
+{
+ return &nfsi->vfs_inode;
+}
static inline struct nfs_inode *NFS_I(const struct inode *inode)
{
return container_of(inode, struct nfs_inode, vfs_inode);
}
+#endif
static inline struct nfs_server *NFS_SB(const struct super_block *s)
{
@@ -328,15 +349,6 @@ static inline int NFS_STALE(const struct inode *inode)
return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
}
-static inline struct fscache_cookie *nfs_i_fscache(struct inode *inode)
-{
-#ifdef CONFIG_NFS_FSCACHE
- return NFS_I(inode)->fscache;
-#else
- return NULL;
-#endif
-}
-
static inline __u64 NFS_FILEID(const struct inode *inode)
{
return NFS_I(inode)->fileid;
--
2.31.1
Convert the NFS buffered read code paths to corresponding netfs APIs,
but only when fscache is configured and enabled.
The netfs API defines struct netfs_request_ops which must be filled
in by the network filesystem. For NFS, we only need to define 5 of
the functions, the main one being the issue_read() function.
The issue_read() function is called by the netfs layer when a read
cannot be fulfilled locally, and must be sent to the server (either
the cache is not active, or it is active but the data is not available).
Once the read from the server is complete, netfs requires a call to
netfs_subreq_terminated() which conveys either how many bytes were read
successfully, or an error. Note that issue_read() is called with a
structure, netfs_io_subrequest, which defines the IO requested, and
contains a start and a length (both in bytes), and assumes the underlying
netfs will return a either an error on the whole region, or the number
of bytes successfully read.
The NFS IO path is page based and the main APIs are the pgio APIs defined
in pagelist.c. For the pgio APIs, there is no way for the caller to
know how many RPCs will be sent and how the pages will be broken up
into underlying RPCs, each of which will have their own return code.
Thus, NFS needs some way to accommodate the netfs API requirement on
the single response to the whole request, while also minimizing
disruptive changes to the NFS pgio layer. The approach taken with this
patch is to allocate a small structure for each call to nfs_issue_read()
to keep some accounting information for the outstanding RPCs, as well as
the final error value or the number of bytes successfully read. The
accounting data is updated inside nfs_netfs_read_initiate(), and
nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
to the data. Then finally in nfs_read_completion(), call into
nfs_netfs_read_completion() to update the final error value and bytes
read, and check the accounting data to determine whether this is the
final RPC completion. If this is the last RPC, then call into
netfs_subreq_terminated() with the final error value or the number
of bytes transferred.
Link: https://lore.kernel.org/linux-nfs/[email protected]/
Signed-off-by: Dave Wysochanski <[email protected]>
---
fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
fs/nfs/fscache.h | 71 +++++++------
fs/nfs/inode.c | 3 +
fs/nfs/internal.h | 9 ++
fs/nfs/pagelist.c | 14 +++
fs/nfs/read.c | 68 ++++++++----
include/linux/nfs_page.h | 3 +
include/linux/nfs_xdr.h | 3 +
8 files changed, 245 insertions(+), 145 deletions(-)
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index a6fc1c8b6644..85f8251a608a 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -15,6 +15,9 @@
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/iversion.h>
+#include <linux/xarray.h>
+#include <linux/fscache.h>
+#include <linux/netfs.h>
#include "internal.h"
#include "iostat.h"
@@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
fscache_unuse_cookie(cookie, &auxdata, &i_size);
}
-/*
- * Fallback page reading interface.
- */
-static int fscache_fallback_read_page(struct inode *inode, struct page *page)
+
+atomic_t nfs_netfs_debug_id;
+static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
{
- struct netfs_cache_resources cres;
- struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
- struct iov_iter iter;
- struct bio_vec bvec[1];
- int ret;
-
- memset(&cres, 0, sizeof(cres));
- bvec[0].bv_page = page;
- bvec[0].bv_offset = 0;
- bvec[0].bv_len = PAGE_SIZE;
- iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
-
- ret = fscache_begin_read_operation(&cres, cookie);
- if (ret < 0)
- return ret;
-
- ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
- NULL, NULL);
- fscache_end_operation(&cres);
- return ret;
+ rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
+
+ if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
+ rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
+
+ return 0;
}
-/*
- * Fallback page writing interface.
- */
-static int fscache_fallback_write_page(struct inode *inode, struct page *page,
- bool no_space_allocated_yet)
+static void nfs_netfs_free_request(struct netfs_io_request *rreq)
{
- struct netfs_cache_resources cres;
- struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
- struct iov_iter iter;
- struct bio_vec bvec[1];
- loff_t start = page_offset(page);
- size_t len = PAGE_SIZE;
- int ret;
-
- memset(&cres, 0, sizeof(cres));
- bvec[0].bv_page = page;
- bvec[0].bv_offset = 0;
- bvec[0].bv_len = PAGE_SIZE;
- iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
-
- ret = fscache_begin_write_operation(&cres, cookie);
- if (ret < 0)
- return ret;
-
- ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
- no_space_allocated_yet);
- if (ret == 0)
- ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
- fscache_end_operation(&cres);
- return ret;
+ put_nfs_open_context(rreq->netfs_priv);
}
-/*
- * Retrieve a page from fscache
- */
-int __nfs_fscache_read_page(struct inode *inode, struct page *page)
+static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
{
- int ret;
+ return fscache_begin_read_operation(&rreq->cache_resources,
+ netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
+}
- trace_nfs_fscache_read_page(inode, page);
- if (PageChecked(page)) {
- ClearPageChecked(page);
- ret = 1;
- goto out;
- }
+static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
+{
+ struct nfs_netfs_io_data *netfs;
+
+ netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
+ if (!netfs)
+ return NULL;
+ netfs->sreq = sreq;
+ refcount_set(&netfs->refcount, 1);
+ spin_lock_init(&netfs->lock);
+ return netfs;
+}
- ret = fscache_fallback_read_page(inode, page);
- if (ret < 0) {
- nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
- SetPageChecked(page);
- goto out;
+static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
+{
+ size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
+
+ sreq->len = min(sreq->len, rsize);
+ return true;
+}
+
+static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
+{
+ struct nfs_pageio_descriptor pgio;
+ struct inode *inode = sreq->rreq->inode;
+ struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
+ struct page *page;
+ int err;
+ pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
+ pgoff_t last = ((sreq->start + sreq->len -
+ sreq->transferred - 1) >> PAGE_SHIFT);
+ XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
+
+ nfs_pageio_init_read(&pgio, inode, false,
+ &nfs_async_read_completion_ops);
+
+ pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
+ if (!pgio.pg_netfs)
+ return netfs_subreq_terminated(sreq, -ENOMEM, false);
+
+ xas_lock(&xas);
+ xas_for_each(&xas, page, last) {
+ /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
+ xas_pause(&xas);
+ xas_unlock(&xas);
+ err = nfs_pageio_add_page(&pgio, ctx, page);
+ if (err < 0)
+ return netfs_subreq_terminated(sreq, err, false);
+ xas_lock(&xas);
}
+ xas_unlock(&xas);
+ nfs_pageio_complete_read(&pgio);
+ nfs_netfs_put(pgio.pg_netfs);
+}
- /* Read completed synchronously */
- nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
- SetPageUptodate(page);
- ret = 0;
-out:
- trace_nfs_fscache_read_page_exit(inode, page, ret);
- return ret;
+void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
+{
+ struct nfs_netfs_io_data *netfs = hdr->netfs;
+
+ if (!netfs)
+ return;
+
+ spin_lock(&netfs->lock);
+ atomic_inc(&netfs->rpcs);
+ netfs->rpc_byte_count += hdr->args.count;
+ spin_unlock(&netfs->lock);
}
-/*
- * Store a newly fetched page in fscache. We can be certain there's no page
- * stored in the cache as yet otherwise we would've read it from there.
- */
-void __nfs_fscache_write_page(struct inode *inode, struct page *page)
+void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
{
- int ret;
+ struct nfs_netfs_io_data *netfs = hdr->netfs;
- trace_nfs_fscache_write_page(inode, page);
+ if (!netfs)
+ return;
+
+ spin_lock(&netfs->lock);
+ if (hdr->res.op_status) {
+ /*
+ * Retryable errors such as BAD_STATEID will be re-issued,
+ * so reduce the bytes and the RPC counts.
+ */
+ netfs->rpc_byte_count -= hdr->args.count;
+ atomic_dec(&netfs->rpcs);
+ }
+ spin_unlock(&netfs->lock);
+}
+
+void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
+{
+ struct nfs_netfs_io_data *netfs = hdr->netfs;
+ struct netfs_io_subrequest *sreq;
+
+ if (!netfs)
+ return;
- ret = fscache_fallback_write_page(inode, page, true);
+ sreq = netfs->sreq;
+ if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
+ __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
- if (ret != 0) {
- nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
- nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
- } else {
- nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
+ spin_lock(&netfs->lock);
+ if (hdr->error)
+ netfs->error = hdr->error;
+ else
+ netfs->transferred += hdr->res.count;
+ spin_unlock(&netfs->lock);
+
+ /* Only the last RPC completion should call netfs_subreq_terminated() */
+ if (atomic_dec_and_test(&netfs->rpcs) &&
+ (netfs->rpc_byte_count >= sreq->len)) {
+ netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
+ nfs_netfs_put(netfs);
+ hdr->netfs = NULL;
}
- trace_nfs_fscache_write_page_exit(inode, page, ret);
}
+
+const struct netfs_request_ops nfs_netfs_ops = {
+ .init_request = nfs_netfs_init_request,
+ .free_request = nfs_netfs_free_request,
+ .begin_cache_operation = nfs_netfs_begin_cache_operation,
+ .issue_read = nfs_netfs_issue_read,
+ .clamp_length = nfs_netfs_clamp_length
+};
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 38614ed8f951..c59a82a7d4a8 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
u64 change_attr;
};
+struct nfs_netfs_io_data {
+ refcount_t refcount;
+ struct netfs_io_subrequest *sreq;
+
+ /*
+ * NFS may split a netfs_io_subrequest into multiple RPCs, each
+ * with their own read completion. In netfs, we can only call
+ * netfs_subreq_terminated() once for each subrequest. So we
+ * must keep track of the rpcs and rpc_byte_count for what has
+ * been submitted, and only call netfs via netfs_subreq_terminated()
+ * when the final RPC has completed.
+ */
+ atomic_t rpcs;
+ unsigned long rpc_byte_count;
+
+ /*
+ * Final dispostion of the netfs_io_subrequest, sent in
+ * netfs_subreq_terminated()
+ */
+ spinlock_t lock;
+ ssize_t transferred;
+ int error;
+};
+
+static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
+{
+ refcount_inc(&netfs->refcount);
+}
+
+static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
+{
+ if (refcount_dec_and_test(&netfs->refcount))
+ kfree(netfs);
+}
+extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
+extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
+extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
+
/*
* fscache.c
*/
@@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
extern void nfs_fscache_open_file(struct inode *, struct file *);
extern void nfs_fscache_release_file(struct inode *, struct file *);
-extern int __nfs_fscache_read_page(struct inode *, struct page *);
-extern void __nfs_fscache_write_page(struct inode *, struct page *);
-
static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
{
if (folio_test_fscache(folio)) {
if (current_is_kswapd() || !(gfp & __GFP_FS))
return false;
folio_wait_fscache(folio);
- fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
- nfs_inc_fscache_stats(folio->mapping->host,
- NFSIOS_FSCACHE_PAGES_UNCACHED);
}
+ fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
return true;
}
-/*
- * Retrieve a page from an inode data storage object.
- */
-static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
-{
- if (netfs_inode(inode)->cache)
- return __nfs_fscache_read_page(inode, page);
- return -ENOBUFS;
-}
-
-/*
- * Store a page newly fetched from the server in an inode data storage object
- * in the cache.
- */
-static inline void nfs_fscache_write_page(struct inode *inode,
- struct page *page)
-{
- if (netfs_inode(inode)->cache)
- __nfs_fscache_write_page(inode, page);
-}
-
static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
struct inode *inode)
{
@@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
{
return true; /* may release folio */
}
-static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
-{
- return -ENOBUFS;
-}
-static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
static inline const char *nfs_server_fscache_state(struct nfs_server *server)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index aa2aec785ab5..a0af3518d8db 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
#endif /* CONFIG_NFS_V4 */
#ifdef CONFIG_NFS_V4_2
nfsi->xattr_cache = NULL;
+#endif
+#ifdef CONFIG_NFS_FSCACHE
+ netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
#endif
return VFS_I(nfsi);
}
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 273687082992..e5589036c1f8 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
extern int nfs_client_for_each_server(struct nfs_client *clp,
int (*fn)(struct nfs_server *, void *),
void *data);
+#ifdef CONFIG_NFS_FSCACHE
+extern const struct netfs_request_ops nfs_netfs_ops;
+#endif
+
/* io.c */
extern void nfs_start_io_read(struct inode *inode);
extern void nfs_end_io_read(struct inode *inode);
@@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
struct nfs_pgio_completion_ops;
/* read.c */
+extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
struct inode *inode, bool force_mds,
const struct nfs_pgio_completion_ops *compl_ops);
+extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
+ struct nfs_open_context *ctx,
+ struct page *page);
+extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 317cedfa52bf..600989332a6f 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -25,6 +25,7 @@
#include "internal.h"
#include "pnfs.h"
#include "nfstrace.h"
+#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
@@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
hdr->good_bytes = mirror->pg_count;
hdr->io_completion = desc->pg_io_completion;
hdr->dreq = desc->pg_dreq;
+#ifdef CONFIG_NFS_FSCACHE
+ if (desc->pg_netfs) {
+ hdr->netfs = desc->pg_netfs;
+ nfs_netfs_get(desc->pg_netfs);
+ }
+#endif
hdr->release = release;
hdr->completion_ops = desc->pg_completion_ops;
if (hdr->completion_ops->init_hdr)
@@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
desc->pg_lseg = NULL;
desc->pg_io_completion = NULL;
desc->pg_dreq = NULL;
+#ifdef CONFIG_NFS_FSCACHE
+ desc->pg_netfs = NULL;
+#endif
desc->pg_bsize = bsize;
desc->pg_mirror_count = 1;
@@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
/* Set up the argument struct */
nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
desc->pg_rpc_callops = &nfs_pgio_common_ops;
+
return 0;
}
EXPORT_SYMBOL_GPL(nfs_generic_pgio);
@@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
desc->pg_io_completion = hdr->io_completion;
desc->pg_dreq = hdr->dreq;
+#ifdef CONFIG_NFS_FSCACHE
+ desc->pg_netfs = hdr->netfs;
+#endif
list_splice_init(&hdr->pages, &pages);
while (!list_empty(&pages)) {
struct nfs_page *req = nfs_list_entry(pages.next);
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 525e82ea9a9e..3bc48472f207 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -30,7 +30,7 @@
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
static const struct nfs_rw_ops nfs_rw_read_ops;
static struct kmem_cache *nfs_rdata_cachep;
@@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
}
EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
-static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
+void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
{
struct nfs_pgio_mirror *pgm;
unsigned long npages;
@@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
static void nfs_readpage_release(struct nfs_page *req, int error)
{
- struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
struct page *page = req->wb_page;
- dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
- (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
- (long long)req_offset(req));
-
if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
SetPageError(page);
if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
- if (PageUptodate(page))
- nfs_fscache_write_page(inode, page);
+#ifdef CONFIG_NFS_FSCACHE
+ struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
+
+ /*
+ * If fscache is enabled, netfs will unlock pages.
+ * Otherwise, we have to unlock the page here
+ */
+ if (!netfs_inode(inode)->cache)
+ unlock_page(page);
+#else
unlock_page(page);
+#endif
}
+
nfs_release_request(req);
}
@@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
nfs_list_remove_request(req);
nfs_readpage_release(req, error);
}
+#ifdef CONFIG_NFS_FSCACHE
+ nfs_netfs_read_completion(hdr);
+#endif
+
out:
hdr->release(hdr);
}
@@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
struct rpc_task_setup *task_setup_data, int how)
{
rpc_ops->read_setup(hdr, msg);
+#ifdef CONFIG_NFS_FSCACHE
+ nfs_netfs_read_initiate(hdr);
+#endif
trace_nfs_initiate_read(hdr);
}
@@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
}
}
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
.error_cleanup = nfs_async_read_error,
.completion = nfs_read_completion,
};
@@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
if (status != 0)
return status;
+#ifdef CONFIG_NFS_FSCACHE
+ nfs_netfs_read_done(hdr);
+#endif
nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
trace_nfs_readpage_done(task, hdr);
@@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
- if (!IS_SYNC(page->mapping->host)) {
- error = nfs_fscache_read_page(page->mapping->host, page);
- if (error == 0)
- goto out_unlock;
- }
-
new = nfs_create_request(ctx, page, 0, aligned_len);
if (IS_ERR(new))
goto out_error;
@@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
return 0;
out_error:
error = PTR_ERR(new);
-out_unlock:
- unlock_page(page);
out:
return error;
}
@@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
if (NFS_STALE(inode))
goto out_unlock;
+#ifdef CONFIG_NFS_FSCACHE
+ if (netfs_inode(inode)->cache) {
+ ret = netfs_read_folio(file, folio);
+ goto out;
+ }
+#endif
if (file == NULL) {
ret = -EBADF;
ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
@@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
&nfs_async_read_completion_ops);
ret = nfs_pageio_add_page(&pgio, ctx, page);
- if (ret)
- goto out;
+ if (ret) {
+ put_nfs_open_context(ctx);
+ goto out_unlock;
+ }
nfs_pageio_complete_read(&pgio);
ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
@@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
if (!PageUptodate(page) && !ret)
ret = xchg(&ctx->error, 0);
}
-out:
put_nfs_open_context(ctx);
- trace_nfs_aop_readpage_done(inode, page, ret);
- return ret;
+ goto out;
+
out_unlock:
unlock_page(page);
+out:
trace_nfs_aop_readpage_done(inode, page, ret);
return ret;
}
@@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
if (NFS_STALE(inode))
goto out;
+#ifdef CONFIG_NFS_FSCACHE
+ if (netfs_inode(inode)->cache) {
+ netfs_readahead(ractl);
+ ret = 0;
+ goto out;
+ }
+#endif
if (file == NULL) {
ret = -EBADF;
ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index ba7e2e4b0926..8eeb16d9bacd 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
struct pnfs_layout_segment *pg_lseg;
struct nfs_io_completion *pg_io_completion;
struct nfs_direct_req *pg_dreq;
+#ifdef CONFIG_NFS_FSCACHE
+ void *pg_netfs;
+#endif
unsigned int pg_bsize; /* default bsize for mirrors */
u32 pg_mirror_count;
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index e86cf6642d21..e196ef595908 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
const struct nfs_rw_ops *rw_ops;
struct nfs_io_completion *io_completion;
struct nfs_direct_req *dreq;
+#ifdef CONFIG_NFS_FSCACHE
+ void *netfs;
+#endif
int pnfs_error;
int error; /* merge with pnfs_error */
--
2.31.1
On Wed, 2022-08-31 at 20:48 -0400, Dave Wysochanski wrote:
> Convert the NFS buffered read code paths to corresponding netfs APIs,
> but only when fscache is configured and enabled.
>
> The netfs API defines struct netfs_request_ops which must be filled
> in by the network filesystem. For NFS, we only need to define 5 of
> the functions, the main one being the issue_read() function.
> The issue_read() function is called by the netfs layer when a read
> cannot be fulfilled locally, and must be sent to the server (either
> the cache is not active, or it is active but the data is not available).
> Once the read from the server is complete, netfs requires a call to
> netfs_subreq_terminated() which conveys either how many bytes were read
> successfully, or an error. Note that issue_read() is called with a
> structure, netfs_io_subrequest, which defines the IO requested, and
> contains a start and a length (both in bytes), and assumes the underlying
> netfs will return a either an error on the whole region, or the number
> of bytes successfully read.
>
> The NFS IO path is page based and the main APIs are the pgio APIs defined
> in pagelist.c. For the pgio APIs, there is no way for the caller to
> know how many RPCs will be sent and how the pages will be broken up
> into underlying RPCs, each of which will have their own return code.
> Thus, NFS needs some way to accommodate the netfs API requirement on
> the single response to the whole request, while also minimizing
> disruptive changes to the NFS pgio layer. The approach taken with this
> patch is to allocate a small structure for each call to nfs_issue_read()
> to keep some accounting information for the outstanding RPCs, as well as
> the final error value or the number of bytes successfully read. The
> accounting data is updated inside nfs_netfs_read_initiate(), and
> nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> to the data. Then finally in nfs_read_completion(), call into
> nfs_netfs_read_completion() to update the final error value and bytes
> read, and check the accounting data to determine whether this is the
> final RPC completion. If this is the last RPC, then call into
> netfs_subreq_terminated() with the final error value or the number
> of bytes transferred.
>
> Link: https://lore.kernel.org/linux-nfs/[email protected]/
>
> Signed-off-by: Dave Wysochanski <[email protected]>
> ---
> fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
> fs/nfs/fscache.h | 71 +++++++------
> fs/nfs/inode.c | 3 +
> fs/nfs/internal.h | 9 ++
> fs/nfs/pagelist.c | 14 +++
> fs/nfs/read.c | 68 ++++++++----
> include/linux/nfs_page.h | 3 +
> include/linux/nfs_xdr.h | 3 +
> 8 files changed, 245 insertions(+), 145 deletions(-)
>
> diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> index a6fc1c8b6644..85f8251a608a 100644
> --- a/fs/nfs/fscache.c
> +++ b/fs/nfs/fscache.c
> @@ -15,6 +15,9 @@
> #include <linux/seq_file.h>
> #include <linux/slab.h>
> #include <linux/iversion.h>
> +#include <linux/xarray.h>
> +#include <linux/fscache.h>
> +#include <linux/netfs.h>
>
> #include "internal.h"
> #include "iostat.h"
> @@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> fscache_unuse_cookie(cookie, &auxdata, &i_size);
> }
>
> -/*
> - * Fallback page reading interface.
> - */
> -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> +
> +atomic_t nfs_netfs_debug_id;
> +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> {
> - struct netfs_cache_resources cres;
> - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> - struct iov_iter iter;
> - struct bio_vec bvec[1];
> - int ret;
> -
> - memset(&cres, 0, sizeof(cres));
> - bvec[0].bv_page = page;
> - bvec[0].bv_offset = 0;
> - bvec[0].bv_len = PAGE_SIZE;
> - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> -
> - ret = fscache_begin_read_operation(&cres, cookie);
> - if (ret < 0)
> - return ret;
> -
> - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> - NULL, NULL);
> - fscache_end_operation(&cres);
> - return ret;
> + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> +
> + if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
> + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> +
> + return 0;
> }
>
> -/*
> - * Fallback page writing interface.
> - */
> -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> - bool no_space_allocated_yet)
> +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> {
> - struct netfs_cache_resources cres;
> - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> - struct iov_iter iter;
> - struct bio_vec bvec[1];
> - loff_t start = page_offset(page);
> - size_t len = PAGE_SIZE;
> - int ret;
> -
> - memset(&cres, 0, sizeof(cres));
> - bvec[0].bv_page = page;
> - bvec[0].bv_offset = 0;
> - bvec[0].bv_len = PAGE_SIZE;
> - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> -
> - ret = fscache_begin_write_operation(&cres, cookie);
> - if (ret < 0)
> - return ret;
> -
> - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> - no_space_allocated_yet);
> - if (ret == 0)
> - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> - fscache_end_operation(&cres);
> - return ret;
> + put_nfs_open_context(rreq->netfs_priv);
> }
>
> -/*
> - * Retrieve a page from fscache
> - */
> -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> {
> - int ret;
> + return fscache_begin_read_operation(&rreq->cache_resources,
> + netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
> +}
>
> - trace_nfs_fscache_read_page(inode, page);
> - if (PageChecked(page)) {
> - ClearPageChecked(page);
> - ret = 1;
> - goto out;
> - }
> +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> +{
> + struct nfs_netfs_io_data *netfs;
> +
> + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> + if (!netfs)
> + return NULL;
> + netfs->sreq = sreq;
> + refcount_set(&netfs->refcount, 1);
> + spin_lock_init(&netfs->lock);
> + return netfs;
> +}
>
> - ret = fscache_fallback_read_page(inode, page);
> - if (ret < 0) {
> - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> - SetPageChecked(page);
> - goto out;
> +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> +{
> + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> +
> + sreq->len = min(sreq->len, rsize);
> + return true;
> +}
> +
> +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> +{
> + struct nfs_pageio_descriptor pgio;
> + struct inode *inode = sreq->rreq->inode;
> + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> + struct page *page;
> + int err;
> + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> + pgoff_t last = ((sreq->start + sreq->len -
> + sreq->transferred - 1) >> PAGE_SHIFT);
> + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> +
> + nfs_pageio_init_read(&pgio, inode, false,
> + &nfs_async_read_completion_ops);
> +
> + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> + if (!pgio.pg_netfs)
> + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> +
> + xas_lock(&xas);
> + xas_for_each(&xas, page, last) {
> + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> + xas_pause(&xas);
> + xas_unlock(&xas);
> + err = nfs_pageio_add_page(&pgio, ctx, page);
> + if (err < 0)
> + return netfs_subreq_terminated(sreq, err, false);
> + xas_lock(&xas);
> }
> + xas_unlock(&xas);
> + nfs_pageio_complete_read(&pgio);
> + nfs_netfs_put(pgio.pg_netfs);
> +}
>
> - /* Read completed synchronously */
> - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> - SetPageUptodate(page);
> - ret = 0;
> -out:
> - trace_nfs_fscache_read_page_exit(inode, page, ret);
> - return ret;
> +void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
> +{
> + struct nfs_netfs_io_data *netfs = hdr->netfs;
> +
> + if (!netfs)
> + return;
> +
> + spin_lock(&netfs->lock);
> + atomic_inc(&netfs->rpcs);
> + netfs->rpc_byte_count += hdr->args.count;
> + spin_unlock(&netfs->lock);
> }
>
> -/*
> - * Store a newly fetched page in fscache. We can be certain there's no page
> - * stored in the cache as yet otherwise we would've read it from there.
> - */
> -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> +void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
> {
> - int ret;
> + struct nfs_netfs_io_data *netfs = hdr->netfs;
>
> - trace_nfs_fscache_write_page(inode, page);
> + if (!netfs)
> + return;
> +
> + spin_lock(&netfs->lock);
> + if (hdr->res.op_status) {
> + /*
> + * Retryable errors such as BAD_STATEID will be re-issued,
> + * so reduce the bytes and the RPC counts.
> + */
> + netfs->rpc_byte_count -= hdr->args.count;
> + atomic_dec(&netfs->rpcs);
> + }
> + spin_unlock(&netfs->lock);
> +}
> +
> +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> +{
> + struct nfs_netfs_io_data *netfs = hdr->netfs;
> + struct netfs_io_subrequest *sreq;
> +
> + if (!netfs)
> + return;
>
> - ret = fscache_fallback_write_page(inode, page, true);
> + sreq = netfs->sreq;
> + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
>
> - if (ret != 0) {
> - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> - } else {
> - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> + spin_lock(&netfs->lock);
> + if (hdr->error)
> + netfs->error = hdr->error;
> + else
> + netfs->transferred += hdr->res.count;
> + spin_unlock(&netfs->lock);
> +
> + /* Only the last RPC completion should call netfs_subreq_terminated() */
> + if (atomic_dec_and_test(&netfs->rpcs) &&
> + (netfs->rpc_byte_count >= sreq->len)) {
I don't quite understand the point of the rpc_byte_count. I guess this
starts out being a total of the requested bytes in the read, and we
decrement the number of bytes in the replies.
This should always be a value that is equal to or larger than the
sreq->len. Why is it necessary to track that, instead of just the number
of RPCs?
> + netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
> + nfs_netfs_put(netfs);
> + hdr->netfs = NULL;
> }
> - trace_nfs_fscache_write_page_exit(inode, page, ret);
> }
> +
> +const struct netfs_request_ops nfs_netfs_ops = {
> + .init_request = nfs_netfs_init_request,
> + .free_request = nfs_netfs_free_request,
> + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> + .issue_read = nfs_netfs_issue_read,
> + .clamp_length = nfs_netfs_clamp_length
> +};
> diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> index 38614ed8f951..c59a82a7d4a8 100644
> --- a/fs/nfs/fscache.h
> +++ b/fs/nfs/fscache.h
> @@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
> u64 change_attr;
> };
>
> +struct nfs_netfs_io_data {
> + refcount_t refcount;
> + struct netfs_io_subrequest *sreq;
> +
> + /*
> + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> + * with their own read completion. In netfs, we can only call
> + * netfs_subreq_terminated() once for each subrequest. So we
> + * must keep track of the rpcs and rpc_byte_count for what has
> + * been submitted, and only call netfs via netfs_subreq_terminated()
> + * when the final RPC has completed.
> + */
> + atomic_t rpcs;
> + unsigned long rpc_byte_count;
> +
> + /*
> + * Final dispostion of the netfs_io_subrequest, sent in
> + * netfs_subreq_terminated()
> + */
> + spinlock_t lock;
> + ssize_t transferred;
> + int error;
> +};
> +
> +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> +{
> + refcount_inc(&netfs->refcount);
> +}
> +
> +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> +{
> + if (refcount_dec_and_test(&netfs->refcount))
> + kfree(netfs);
> +}
> +extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
> +extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
> +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> +
> /*
> * fscache.c
> */
> @@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
> extern void nfs_fscache_open_file(struct inode *, struct file *);
> extern void nfs_fscache_release_file(struct inode *, struct file *);
>
> -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> -
> static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> {
> if (folio_test_fscache(folio)) {
> if (current_is_kswapd() || !(gfp & __GFP_FS))
> return false;
> folio_wait_fscache(folio);
> - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> - nfs_inc_fscache_stats(folio->mapping->host,
> - NFSIOS_FSCACHE_PAGES_UNCACHED);
> }
> + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> return true;
> }
>
> -/*
> - * Retrieve a page from an inode data storage object.
> - */
> -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> -{
> - if (netfs_inode(inode)->cache)
> - return __nfs_fscache_read_page(inode, page);
> - return -ENOBUFS;
> -}
> -
> -/*
> - * Store a page newly fetched from the server in an inode data storage object
> - * in the cache.
> - */
> -static inline void nfs_fscache_write_page(struct inode *inode,
> - struct page *page)
> -{
> - if (netfs_inode(inode)->cache)
> - __nfs_fscache_write_page(inode, page);
> -}
> -
> static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> struct inode *inode)
> {
> @@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> {
> return true; /* may release folio */
> }
> -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> -{
> - return -ENOBUFS;
> -}
> -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
>
> static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index aa2aec785ab5..a0af3518d8db 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> #endif /* CONFIG_NFS_V4 */
> #ifdef CONFIG_NFS_V4_2
> nfsi->xattr_cache = NULL;
> +#endif
> +#ifdef CONFIG_NFS_FSCACHE
> + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> #endif
> return VFS_I(nfsi);
> }
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 273687082992..e5589036c1f8 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> extern int nfs_client_for_each_server(struct nfs_client *clp,
> int (*fn)(struct nfs_server *, void *),
> void *data);
> +#ifdef CONFIG_NFS_FSCACHE
> +extern const struct netfs_request_ops nfs_netfs_ops;
> +#endif
> +
> /* io.c */
> extern void nfs_start_io_read(struct inode *inode);
> extern void nfs_end_io_read(struct inode *inode);
> @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
>
> struct nfs_pgio_completion_ops;
> /* read.c */
> +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> struct inode *inode, bool force_mds,
> const struct nfs_pgio_completion_ops *compl_ops);
> +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> + struct nfs_open_context *ctx,
> + struct page *page);
> +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
>
> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> index 317cedfa52bf..600989332a6f 100644
> --- a/fs/nfs/pagelist.c
> +++ b/fs/nfs/pagelist.c
> @@ -25,6 +25,7 @@
> #include "internal.h"
> #include "pnfs.h"
> #include "nfstrace.h"
> +#include "fscache.h"
>
> #define NFSDBG_FACILITY NFSDBG_PAGECACHE
>
> @@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> hdr->good_bytes = mirror->pg_count;
> hdr->io_completion = desc->pg_io_completion;
> hdr->dreq = desc->pg_dreq;
> +#ifdef CONFIG_NFS_FSCACHE
> + if (desc->pg_netfs) {
> + hdr->netfs = desc->pg_netfs;
> + nfs_netfs_get(desc->pg_netfs);
> + }
> +#endif
> hdr->release = release;
> hdr->completion_ops = desc->pg_completion_ops;
> if (hdr->completion_ops->init_hdr)
> @@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> desc->pg_lseg = NULL;
> desc->pg_io_completion = NULL;
> desc->pg_dreq = NULL;
> +#ifdef CONFIG_NFS_FSCACHE
> + desc->pg_netfs = NULL;
> +#endif
> desc->pg_bsize = bsize;
>
> desc->pg_mirror_count = 1;
> @@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> /* Set up the argument struct */
> nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> desc->pg_rpc_callops = &nfs_pgio_common_ops;
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> @@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
>
> desc->pg_io_completion = hdr->io_completion;
> desc->pg_dreq = hdr->dreq;
> +#ifdef CONFIG_NFS_FSCACHE
> + desc->pg_netfs = hdr->netfs;
> +#endif
> list_splice_init(&hdr->pages, &pages);
> while (!list_empty(&pages)) {
> struct nfs_page *req = nfs_list_entry(pages.next);
> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> index 525e82ea9a9e..3bc48472f207 100644
> --- a/fs/nfs/read.c
> +++ b/fs/nfs/read.c
> @@ -30,7 +30,7 @@
>
> #define NFSDBG_FACILITY NFSDBG_PAGECACHE
>
> -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> static const struct nfs_rw_ops nfs_rw_read_ops;
>
> static struct kmem_cache *nfs_rdata_cachep;
> @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> }
> EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
>
> -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> {
> struct nfs_pgio_mirror *pgm;
> unsigned long npages;
> @@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
>
> static void nfs_readpage_release(struct nfs_page *req, int error)
> {
> - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> struct page *page = req->wb_page;
>
> - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> - (long long)req_offset(req));
> -
> if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> SetPageError(page);
> if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> - if (PageUptodate(page))
> - nfs_fscache_write_page(inode, page);
> +#ifdef CONFIG_NFS_FSCACHE
> + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> +
> + /*
> + * If fscache is enabled, netfs will unlock pages.
> + * Otherwise, we have to unlock the page here
> + */
> + if (!netfs_inode(inode)->cache)
> + unlock_page(page);
> +#else
> unlock_page(page);
> +#endif
> }
> +
> nfs_release_request(req);
> }
>
> @@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> nfs_list_remove_request(req);
> nfs_readpage_release(req, error);
> }
> +#ifdef CONFIG_NFS_FSCACHE
> + nfs_netfs_read_completion(hdr);
> +#endif
> +
> out:
> hdr->release(hdr);
> }
> @@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> struct rpc_task_setup *task_setup_data, int how)
> {
> rpc_ops->read_setup(hdr, msg);
> +#ifdef CONFIG_NFS_FSCACHE
> + nfs_netfs_read_initiate(hdr);
> +#endif
> trace_nfs_initiate_read(hdr);
> }
>
> @@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
> }
> }
>
> -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> .error_cleanup = nfs_async_read_error,
> .completion = nfs_read_completion,
> };
> @@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
> if (status != 0)
> return status;
>
> +#ifdef CONFIG_NFS_FSCACHE
> + nfs_netfs_read_done(hdr);
> +#endif
> nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> trace_nfs_readpage_done(task, hdr);
>
> @@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
>
> aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
>
> - if (!IS_SYNC(page->mapping->host)) {
> - error = nfs_fscache_read_page(page->mapping->host, page);
> - if (error == 0)
> - goto out_unlock;
> - }
> -
> new = nfs_create_request(ctx, page, 0, aligned_len);
> if (IS_ERR(new))
> goto out_error;
> @@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> return 0;
> out_error:
> error = PTR_ERR(new);
> -out_unlock:
> - unlock_page(page);
> out:
> return error;
> }
> @@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> if (NFS_STALE(inode))
> goto out_unlock;
>
> +#ifdef CONFIG_NFS_FSCACHE
> + if (netfs_inode(inode)->cache) {
> + ret = netfs_read_folio(file, folio);
> + goto out;
> + }
> +#endif
> if (file == NULL) {
> ret = -EBADF;
> ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> @@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> &nfs_async_read_completion_ops);
>
> ret = nfs_pageio_add_page(&pgio, ctx, page);
> - if (ret)
> - goto out;
> + if (ret) {
> + put_nfs_open_context(ctx);
> + goto out_unlock;
> + }
>
> nfs_pageio_complete_read(&pgio);
> ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> @@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> if (!PageUptodate(page) && !ret)
> ret = xchg(&ctx->error, 0);
> }
> -out:
> put_nfs_open_context(ctx);
> - trace_nfs_aop_readpage_done(inode, page, ret);
> - return ret;
> + goto out;
> +
> out_unlock:
> unlock_page(page);
> +out:
> trace_nfs_aop_readpage_done(inode, page, ret);
> return ret;
> }
> @@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
> if (NFS_STALE(inode))
> goto out;
>
> +#ifdef CONFIG_NFS_FSCACHE
> + if (netfs_inode(inode)->cache) {
> + netfs_readahead(ractl);
> + ret = 0;
> + goto out;
> + }
> +#endif
> if (file == NULL) {
> ret = -EBADF;
> ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> index ba7e2e4b0926..8eeb16d9bacd 100644
> --- a/include/linux/nfs_page.h
> +++ b/include/linux/nfs_page.h
> @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> struct pnfs_layout_segment *pg_lseg;
> struct nfs_io_completion *pg_io_completion;
> struct nfs_direct_req *pg_dreq;
> +#ifdef CONFIG_NFS_FSCACHE
> + void *pg_netfs;
> +#endif
> unsigned int pg_bsize; /* default bsize for mirrors */
>
> u32 pg_mirror_count;
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index e86cf6642d21..e196ef595908 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> const struct nfs_rw_ops *rw_ops;
> struct nfs_io_completion *io_completion;
> struct nfs_direct_req *dreq;
> +#ifdef CONFIG_NFS_FSCACHE
> + void *netfs;
> +#endif
>
> int pnfs_error;
> int error; /* merge with pnfs_error */
--
Jeff Layton <[email protected]>
On Thu, Sep 1, 2022 at 8:45 AM Jeff Layton <[email protected]> wrote:
>
> On Wed, 2022-08-31 at 20:48 -0400, Dave Wysochanski wrote:
> > Convert the NFS buffered read code paths to corresponding netfs APIs,
> > but only when fscache is configured and enabled.
> >
> > The netfs API defines struct netfs_request_ops which must be filled
> > in by the network filesystem. For NFS, we only need to define 5 of
> > the functions, the main one being the issue_read() function.
> > The issue_read() function is called by the netfs layer when a read
> > cannot be fulfilled locally, and must be sent to the server (either
> > the cache is not active, or it is active but the data is not available).
> > Once the read from the server is complete, netfs requires a call to
> > netfs_subreq_terminated() which conveys either how many bytes were read
> > successfully, or an error. Note that issue_read() is called with a
> > structure, netfs_io_subrequest, which defines the IO requested, and
> > contains a start and a length (both in bytes), and assumes the underlying
> > netfs will return a either an error on the whole region, or the number
> > of bytes successfully read.
> >
> > The NFS IO path is page based and the main APIs are the pgio APIs defined
> > in pagelist.c. For the pgio APIs, there is no way for the caller to
> > know how many RPCs will be sent and how the pages will be broken up
> > into underlying RPCs, each of which will have their own return code.
> > Thus, NFS needs some way to accommodate the netfs API requirement on
> > the single response to the whole request, while also minimizing
> > disruptive changes to the NFS pgio layer. The approach taken with this
> > patch is to allocate a small structure for each call to nfs_issue_read()
> > to keep some accounting information for the outstanding RPCs, as well as
> > the final error value or the number of bytes successfully read. The
> > accounting data is updated inside nfs_netfs_read_initiate(), and
> > nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> > to the data. Then finally in nfs_read_completion(), call into
> > nfs_netfs_read_completion() to update the final error value and bytes
> > read, and check the accounting data to determine whether this is the
> > final RPC completion. If this is the last RPC, then call into
> > netfs_subreq_terminated() with the final error value or the number
> > of bytes transferred.
> >
> > Link: https://lore.kernel.org/linux-nfs/[email protected]/
> >
> > Signed-off-by: Dave Wysochanski <[email protected]>
> > ---
> > fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
> > fs/nfs/fscache.h | 71 +++++++------
> > fs/nfs/inode.c | 3 +
> > fs/nfs/internal.h | 9 ++
> > fs/nfs/pagelist.c | 14 +++
> > fs/nfs/read.c | 68 ++++++++----
> > include/linux/nfs_page.h | 3 +
> > include/linux/nfs_xdr.h | 3 +
> > 8 files changed, 245 insertions(+), 145 deletions(-)
> >
> > diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> > index a6fc1c8b6644..85f8251a608a 100644
> > --- a/fs/nfs/fscache.c
> > +++ b/fs/nfs/fscache.c
> > @@ -15,6 +15,9 @@
> > #include <linux/seq_file.h>
> > #include <linux/slab.h>
> > #include <linux/iversion.h>
> > +#include <linux/xarray.h>
> > +#include <linux/fscache.h>
> > +#include <linux/netfs.h>
> >
> > #include "internal.h"
> > #include "iostat.h"
> > @@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> > fscache_unuse_cookie(cookie, &auxdata, &i_size);
> > }
> >
> > -/*
> > - * Fallback page reading interface.
> > - */
> > -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> > +
> > +atomic_t nfs_netfs_debug_id;
> > +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> > {
> > - struct netfs_cache_resources cres;
> > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > - struct iov_iter iter;
> > - struct bio_vec bvec[1];
> > - int ret;
> > -
> > - memset(&cres, 0, sizeof(cres));
> > - bvec[0].bv_page = page;
> > - bvec[0].bv_offset = 0;
> > - bvec[0].bv_len = PAGE_SIZE;
> > - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > -
> > - ret = fscache_begin_read_operation(&cres, cookie);
> > - if (ret < 0)
> > - return ret;
> > -
> > - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> > - NULL, NULL);
> > - fscache_end_operation(&cres);
> > - return ret;
> > + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> > +
> > + if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
> > + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> > +
> > + return 0;
> > }
> >
> > -/*
> > - * Fallback page writing interface.
> > - */
> > -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> > - bool no_space_allocated_yet)
> > +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> > {
> > - struct netfs_cache_resources cres;
> > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > - struct iov_iter iter;
> > - struct bio_vec bvec[1];
> > - loff_t start = page_offset(page);
> > - size_t len = PAGE_SIZE;
> > - int ret;
> > -
> > - memset(&cres, 0, sizeof(cres));
> > - bvec[0].bv_page = page;
> > - bvec[0].bv_offset = 0;
> > - bvec[0].bv_len = PAGE_SIZE;
> > - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > -
> > - ret = fscache_begin_write_operation(&cres, cookie);
> > - if (ret < 0)
> > - return ret;
> > -
> > - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> > - no_space_allocated_yet);
> > - if (ret == 0)
> > - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> > - fscache_end_operation(&cres);
> > - return ret;
> > + put_nfs_open_context(rreq->netfs_priv);
> > }
> >
> > -/*
> > - * Retrieve a page from fscache
> > - */
> > -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> > +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> > {
> > - int ret;
> > + return fscache_begin_read_operation(&rreq->cache_resources,
> > + netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
> > +}
> >
> > - trace_nfs_fscache_read_page(inode, page);
> > - if (PageChecked(page)) {
> > - ClearPageChecked(page);
> > - ret = 1;
> > - goto out;
> > - }
> > +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> > +{
> > + struct nfs_netfs_io_data *netfs;
> > +
> > + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> > + if (!netfs)
> > + return NULL;
> > + netfs->sreq = sreq;
> > + refcount_set(&netfs->refcount, 1);
> > + spin_lock_init(&netfs->lock);
> > + return netfs;
> > +}
> >
> > - ret = fscache_fallback_read_page(inode, page);
> > - if (ret < 0) {
> > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> > - SetPageChecked(page);
> > - goto out;
> > +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> > +{
> > + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> > +
> > + sreq->len = min(sreq->len, rsize);
> > + return true;
> > +}
> > +
> > +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> > +{
> > + struct nfs_pageio_descriptor pgio;
> > + struct inode *inode = sreq->rreq->inode;
> > + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> > + struct page *page;
> > + int err;
> > + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> > + pgoff_t last = ((sreq->start + sreq->len -
> > + sreq->transferred - 1) >> PAGE_SHIFT);
> > + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> > +
> > + nfs_pageio_init_read(&pgio, inode, false,
> > + &nfs_async_read_completion_ops);
> > +
> > + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> > + if (!pgio.pg_netfs)
> > + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> > +
> > + xas_lock(&xas);
> > + xas_for_each(&xas, page, last) {
> > + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> > + xas_pause(&xas);
> > + xas_unlock(&xas);
> > + err = nfs_pageio_add_page(&pgio, ctx, page);
> > + if (err < 0)
> > + return netfs_subreq_terminated(sreq, err, false);
> > + xas_lock(&xas);
> > }
> > + xas_unlock(&xas);
> > + nfs_pageio_complete_read(&pgio);
> > + nfs_netfs_put(pgio.pg_netfs);
> > +}
> >
> > - /* Read completed synchronously */
> > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> > - SetPageUptodate(page);
> > - ret = 0;
> > -out:
> > - trace_nfs_fscache_read_page_exit(inode, page, ret);
> > - return ret;
> > +void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
> > +{
> > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > +
> > + if (!netfs)
> > + return;
> > +
> > + spin_lock(&netfs->lock);
> > + atomic_inc(&netfs->rpcs);
> > + netfs->rpc_byte_count += hdr->args.count;
> > + spin_unlock(&netfs->lock);
> > }
> >
> > -/*
> > - * Store a newly fetched page in fscache. We can be certain there's no page
> > - * stored in the cache as yet otherwise we would've read it from there.
> > - */
> > -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> > +void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
> > {
> > - int ret;
> > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> >
> > - trace_nfs_fscache_write_page(inode, page);
> > + if (!netfs)
> > + return;
> > +
> > + spin_lock(&netfs->lock);
> > + if (hdr->res.op_status) {
> > + /*
> > + * Retryable errors such as BAD_STATEID will be re-issued,
> > + * so reduce the bytes and the RPC counts.
> > + */
> > + netfs->rpc_byte_count -= hdr->args.count;
> > + atomic_dec(&netfs->rpcs);
> > + }
> > + spin_unlock(&netfs->lock);
> > +}
> > +
> > +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> > +{
> > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > + struct netfs_io_subrequest *sreq;
> > +
> > + if (!netfs)
> > + return;
> >
> > - ret = fscache_fallback_write_page(inode, page, true);
> > + sreq = netfs->sreq;
> > + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> > + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
> >
> > - if (ret != 0) {
> > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> > - } else {
> > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> > + spin_lock(&netfs->lock);
> > + if (hdr->error)
> > + netfs->error = hdr->error;
> > + else
> > + netfs->transferred += hdr->res.count;
> > + spin_unlock(&netfs->lock);
> > +
> > + /* Only the last RPC completion should call netfs_subreq_terminated() */
> > + if (atomic_dec_and_test(&netfs->rpcs) &&
> > + (netfs->rpc_byte_count >= sreq->len)) {
>
> I don't quite understand the point of the rpc_byte_count. I guess this
> starts out being a total of the requested bytes in the read, and we
> decrement the number of bytes in the replies.
>
> This should always be a value that is equal to or larger than the
> sreq->len. Why is it necessary to track that, instead of just the number
> of RPCs?
>
As far as I know there's nothing stopping the count of RPCs from going to 0
before you end up sending all the RPCs.
Example: Suppose for a single netfs subreq you can get two NFS
RPCs that both need to complete before the netfs subreq completes.
As far as I know you could get the scenario of:
send RPC1 (rpcs == 1)
receive RPC1 (rpcs == 0)
send RPC2
receive RPC2
> > + netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
> > + nfs_netfs_put(netfs);
> > + hdr->netfs = NULL;
> > }
> > - trace_nfs_fscache_write_page_exit(inode, page, ret);
> > }
> > +
> > +const struct netfs_request_ops nfs_netfs_ops = {
> > + .init_request = nfs_netfs_init_request,
> > + .free_request = nfs_netfs_free_request,
> > + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> > + .issue_read = nfs_netfs_issue_read,
> > + .clamp_length = nfs_netfs_clamp_length
> > +};
> > diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> > index 38614ed8f951..c59a82a7d4a8 100644
> > --- a/fs/nfs/fscache.h
> > +++ b/fs/nfs/fscache.h
> > @@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
> > u64 change_attr;
> > };
> >
> > +struct nfs_netfs_io_data {
> > + refcount_t refcount;
> > + struct netfs_io_subrequest *sreq;
> > +
> > + /*
> > + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> > + * with their own read completion. In netfs, we can only call
> > + * netfs_subreq_terminated() once for each subrequest. So we
> > + * must keep track of the rpcs and rpc_byte_count for what has
> > + * been submitted, and only call netfs via netfs_subreq_terminated()
> > + * when the final RPC has completed.
> > + */
> > + atomic_t rpcs;
> > + unsigned long rpc_byte_count;
> > +
> > + /*
> > + * Final dispostion of the netfs_io_subrequest, sent in
> > + * netfs_subreq_terminated()
> > + */
> > + spinlock_t lock;
> > + ssize_t transferred;
> > + int error;
> > +};
> > +
> > +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> > +{
> > + refcount_inc(&netfs->refcount);
> > +}
> > +
> > +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> > +{
> > + if (refcount_dec_and_test(&netfs->refcount))
> > + kfree(netfs);
> > +}
> > +extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
> > +extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
> > +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> > +
> > /*
> > * fscache.c
> > */
> > @@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
> > extern void nfs_fscache_open_file(struct inode *, struct file *);
> > extern void nfs_fscache_release_file(struct inode *, struct file *);
> >
> > -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> > -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> > -
> > static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > {
> > if (folio_test_fscache(folio)) {
> > if (current_is_kswapd() || !(gfp & __GFP_FS))
> > return false;
> > folio_wait_fscache(folio);
> > - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > - nfs_inc_fscache_stats(folio->mapping->host,
> > - NFSIOS_FSCACHE_PAGES_UNCACHED);
> > }
> > + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > return true;
> > }
> >
> > -/*
> > - * Retrieve a page from an inode data storage object.
> > - */
> > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > -{
> > - if (netfs_inode(inode)->cache)
> > - return __nfs_fscache_read_page(inode, page);
> > - return -ENOBUFS;
> > -}
> > -
> > -/*
> > - * Store a page newly fetched from the server in an inode data storage object
> > - * in the cache.
> > - */
> > -static inline void nfs_fscache_write_page(struct inode *inode,
> > - struct page *page)
> > -{
> > - if (netfs_inode(inode)->cache)
> > - __nfs_fscache_write_page(inode, page);
> > -}
> > -
> > static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> > struct inode *inode)
> > {
> > @@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > {
> > return true; /* may release folio */
> > }
> > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > -{
> > - return -ENOBUFS;
> > -}
> > -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> > static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
> >
> > static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> > index aa2aec785ab5..a0af3518d8db 100644
> > --- a/fs/nfs/inode.c
> > +++ b/fs/nfs/inode.c
> > @@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> > #endif /* CONFIG_NFS_V4 */
> > #ifdef CONFIG_NFS_V4_2
> > nfsi->xattr_cache = NULL;
> > +#endif
> > +#ifdef CONFIG_NFS_FSCACHE
> > + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> > #endif
> > return VFS_I(nfsi);
> > }
> > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > index 273687082992..e5589036c1f8 100644
> > --- a/fs/nfs/internal.h
> > +++ b/fs/nfs/internal.h
> > @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> > extern int nfs_client_for_each_server(struct nfs_client *clp,
> > int (*fn)(struct nfs_server *, void *),
> > void *data);
> > +#ifdef CONFIG_NFS_FSCACHE
> > +extern const struct netfs_request_ops nfs_netfs_ops;
> > +#endif
> > +
> > /* io.c */
> > extern void nfs_start_io_read(struct inode *inode);
> > extern void nfs_end_io_read(struct inode *inode);
> > @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
> >
> > struct nfs_pgio_completion_ops;
> > /* read.c */
> > +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > struct inode *inode, bool force_mds,
> > const struct nfs_pgio_completion_ops *compl_ops);
> > +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > + struct nfs_open_context *ctx,
> > + struct page *page);
> > +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> > extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> > extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
> >
> > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> > index 317cedfa52bf..600989332a6f 100644
> > --- a/fs/nfs/pagelist.c
> > +++ b/fs/nfs/pagelist.c
> > @@ -25,6 +25,7 @@
> > #include "internal.h"
> > #include "pnfs.h"
> > #include "nfstrace.h"
> > +#include "fscache.h"
> >
> > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> >
> > @@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> > hdr->good_bytes = mirror->pg_count;
> > hdr->io_completion = desc->pg_io_completion;
> > hdr->dreq = desc->pg_dreq;
> > +#ifdef CONFIG_NFS_FSCACHE
> > + if (desc->pg_netfs) {
> > + hdr->netfs = desc->pg_netfs;
> > + nfs_netfs_get(desc->pg_netfs);
> > + }
> > +#endif
> > hdr->release = release;
> > hdr->completion_ops = desc->pg_completion_ops;
> > if (hdr->completion_ops->init_hdr)
> > @@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> > desc->pg_lseg = NULL;
> > desc->pg_io_completion = NULL;
> > desc->pg_dreq = NULL;
> > +#ifdef CONFIG_NFS_FSCACHE
> > + desc->pg_netfs = NULL;
> > +#endif
> > desc->pg_bsize = bsize;
> >
> > desc->pg_mirror_count = 1;
> > @@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> > /* Set up the argument struct */
> > nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> > desc->pg_rpc_callops = &nfs_pgio_common_ops;
> > +
> > return 0;
> > }
> > EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> > @@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
> >
> > desc->pg_io_completion = hdr->io_completion;
> > desc->pg_dreq = hdr->dreq;
> > +#ifdef CONFIG_NFS_FSCACHE
> > + desc->pg_netfs = hdr->netfs;
> > +#endif
> > list_splice_init(&hdr->pages, &pages);
> > while (!list_empty(&pages)) {
> > struct nfs_page *req = nfs_list_entry(pages.next);
> > diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> > index 525e82ea9a9e..3bc48472f207 100644
> > --- a/fs/nfs/read.c
> > +++ b/fs/nfs/read.c
> > @@ -30,7 +30,7 @@
> >
> > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> >
> > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > static const struct nfs_rw_ops nfs_rw_read_ops;
> >
> > static struct kmem_cache *nfs_rdata_cachep;
> > @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > }
> > EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
> >
> > -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > {
> > struct nfs_pgio_mirror *pgm;
> > unsigned long npages;
> > @@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
> >
> > static void nfs_readpage_release(struct nfs_page *req, int error)
> > {
> > - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > struct page *page = req->wb_page;
> >
> > - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> > - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> > - (long long)req_offset(req));
> > -
> > if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> > SetPageError(page);
> > if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> > - if (PageUptodate(page))
> > - nfs_fscache_write_page(inode, page);
> > +#ifdef CONFIG_NFS_FSCACHE
> > + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > +
> > + /*
> > + * If fscache is enabled, netfs will unlock pages.
> > + * Otherwise, we have to unlock the page here
> > + */
> > + if (!netfs_inode(inode)->cache)
> > + unlock_page(page);
> > +#else
> > unlock_page(page);
> > +#endif
> > }
> > +
> > nfs_release_request(req);
> > }
> >
> > @@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> > nfs_list_remove_request(req);
> > nfs_readpage_release(req, error);
> > }
> > +#ifdef CONFIG_NFS_FSCACHE
> > + nfs_netfs_read_completion(hdr);
> > +#endif
> > +
> > out:
> > hdr->release(hdr);
> > }
> > @@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> > struct rpc_task_setup *task_setup_data, int how)
> > {
> > rpc_ops->read_setup(hdr, msg);
> > +#ifdef CONFIG_NFS_FSCACHE
> > + nfs_netfs_read_initiate(hdr);
> > +#endif
> > trace_nfs_initiate_read(hdr);
> > }
> >
> > @@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
> > }
> > }
> >
> > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > .error_cleanup = nfs_async_read_error,
> > .completion = nfs_read_completion,
> > };
> > @@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
> > if (status != 0)
> > return status;
> >
> > +#ifdef CONFIG_NFS_FSCACHE
> > + nfs_netfs_read_done(hdr);
> > +#endif
> > nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> > trace_nfs_readpage_done(task, hdr);
> >
> > @@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> >
> > aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
> >
> > - if (!IS_SYNC(page->mapping->host)) {
> > - error = nfs_fscache_read_page(page->mapping->host, page);
> > - if (error == 0)
> > - goto out_unlock;
> > - }
> > -
> > new = nfs_create_request(ctx, page, 0, aligned_len);
> > if (IS_ERR(new))
> > goto out_error;
> > @@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > return 0;
> > out_error:
> > error = PTR_ERR(new);
> > -out_unlock:
> > - unlock_page(page);
> > out:
> > return error;
> > }
> > @@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > if (NFS_STALE(inode))
> > goto out_unlock;
> >
> > +#ifdef CONFIG_NFS_FSCACHE
> > + if (netfs_inode(inode)->cache) {
> > + ret = netfs_read_folio(file, folio);
> > + goto out;
> > + }
> > +#endif
> > if (file == NULL) {
> > ret = -EBADF;
> > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > @@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > &nfs_async_read_completion_ops);
> >
> > ret = nfs_pageio_add_page(&pgio, ctx, page);
> > - if (ret)
> > - goto out;
> > + if (ret) {
> > + put_nfs_open_context(ctx);
> > + goto out_unlock;
> > + }
> >
> > nfs_pageio_complete_read(&pgio);
> > ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> > @@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > if (!PageUptodate(page) && !ret)
> > ret = xchg(&ctx->error, 0);
> > }
> > -out:
> > put_nfs_open_context(ctx);
> > - trace_nfs_aop_readpage_done(inode, page, ret);
> > - return ret;
> > + goto out;
> > +
> > out_unlock:
> > unlock_page(page);
> > +out:
> > trace_nfs_aop_readpage_done(inode, page, ret);
> > return ret;
> > }
> > @@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
> > if (NFS_STALE(inode))
> > goto out;
> >
> > +#ifdef CONFIG_NFS_FSCACHE
> > + if (netfs_inode(inode)->cache) {
> > + netfs_readahead(ractl);
> > + ret = 0;
> > + goto out;
> > + }
> > +#endif
> > if (file == NULL) {
> > ret = -EBADF;
> > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> > index ba7e2e4b0926..8eeb16d9bacd 100644
> > --- a/include/linux/nfs_page.h
> > +++ b/include/linux/nfs_page.h
> > @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> > struct pnfs_layout_segment *pg_lseg;
> > struct nfs_io_completion *pg_io_completion;
> > struct nfs_direct_req *pg_dreq;
> > +#ifdef CONFIG_NFS_FSCACHE
> > + void *pg_netfs;
> > +#endif
> > unsigned int pg_bsize; /* default bsize for mirrors */
> >
> > u32 pg_mirror_count;
> > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > index e86cf6642d21..e196ef595908 100644
> > --- a/include/linux/nfs_xdr.h
> > +++ b/include/linux/nfs_xdr.h
> > @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> > const struct nfs_rw_ops *rw_ops;
> > struct nfs_io_completion *io_completion;
> > struct nfs_direct_req *dreq;
> > +#ifdef CONFIG_NFS_FSCACHE
> > + void *netfs;
> > +#endif
> >
> > int pnfs_error;
> > int error; /* merge with pnfs_error */
>
> --
> Jeff Layton <[email protected]>
>
On Thu, Sep 1, 2022 at 9:38 AM David Wysochanski <[email protected]> wrote:
>
> On Thu, Sep 1, 2022 at 8:45 AM Jeff Layton <[email protected]> wrote:
> >
> > On Wed, 2022-08-31 at 20:48 -0400, Dave Wysochanski wrote:
> > > Convert the NFS buffered read code paths to corresponding netfs APIs,
> > > but only when fscache is configured and enabled.
> > >
> > > The netfs API defines struct netfs_request_ops which must be filled
> > > in by the network filesystem. For NFS, we only need to define 5 of
> > > the functions, the main one being the issue_read() function.
> > > The issue_read() function is called by the netfs layer when a read
> > > cannot be fulfilled locally, and must be sent to the server (either
> > > the cache is not active, or it is active but the data is not available).
> > > Once the read from the server is complete, netfs requires a call to
> > > netfs_subreq_terminated() which conveys either how many bytes were read
> > > successfully, or an error. Note that issue_read() is called with a
> > > structure, netfs_io_subrequest, which defines the IO requested, and
> > > contains a start and a length (both in bytes), and assumes the underlying
> > > netfs will return a either an error on the whole region, or the number
> > > of bytes successfully read.
> > >
> > > The NFS IO path is page based and the main APIs are the pgio APIs defined
> > > in pagelist.c. For the pgio APIs, there is no way for the caller to
> > > know how many RPCs will be sent and how the pages will be broken up
> > > into underlying RPCs, each of which will have their own return code.
> > > Thus, NFS needs some way to accommodate the netfs API requirement on
> > > the single response to the whole request, while also minimizing
> > > disruptive changes to the NFS pgio layer. The approach taken with this
> > > patch is to allocate a small structure for each call to nfs_issue_read()
> > > to keep some accounting information for the outstanding RPCs, as well as
> > > the final error value or the number of bytes successfully read. The
> > > accounting data is updated inside nfs_netfs_read_initiate(), and
> > > nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> > > to the data. Then finally in nfs_read_completion(), call into
> > > nfs_netfs_read_completion() to update the final error value and bytes
> > > read, and check the accounting data to determine whether this is the
> > > final RPC completion. If this is the last RPC, then call into
> > > netfs_subreq_terminated() with the final error value or the number
> > > of bytes transferred.
> > >
> > > Link: https://lore.kernel.org/linux-nfs/[email protected]/
> > >
> > > Signed-off-by: Dave Wysochanski <[email protected]>
> > > ---
> > > fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
> > > fs/nfs/fscache.h | 71 +++++++------
> > > fs/nfs/inode.c | 3 +
> > > fs/nfs/internal.h | 9 ++
> > > fs/nfs/pagelist.c | 14 +++
> > > fs/nfs/read.c | 68 ++++++++----
> > > include/linux/nfs_page.h | 3 +
> > > include/linux/nfs_xdr.h | 3 +
> > > 8 files changed, 245 insertions(+), 145 deletions(-)
> > >
> > > diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> > > index a6fc1c8b6644..85f8251a608a 100644
> > > --- a/fs/nfs/fscache.c
> > > +++ b/fs/nfs/fscache.c
> > > @@ -15,6 +15,9 @@
> > > #include <linux/seq_file.h>
> > > #include <linux/slab.h>
> > > #include <linux/iversion.h>
> > > +#include <linux/xarray.h>
> > > +#include <linux/fscache.h>
> > > +#include <linux/netfs.h>
> > >
> > > #include "internal.h"
> > > #include "iostat.h"
> > > @@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> > > fscache_unuse_cookie(cookie, &auxdata, &i_size);
> > > }
> > >
> > > -/*
> > > - * Fallback page reading interface.
> > > - */
> > > -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> > > +
> > > +atomic_t nfs_netfs_debug_id;
> > > +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_read_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> > > - NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> > > +
> > > + if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
> > > + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> > > +
> > > + return 0;
> > > }
> > >
> > > -/*
> > > - * Fallback page writing interface.
> > > - */
> > > -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> > > - bool no_space_allocated_yet)
> > > +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - loff_t start = page_offset(page);
> > > - size_t len = PAGE_SIZE;
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_write_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> > > - no_space_allocated_yet);
> > > - if (ret == 0)
> > > - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + put_nfs_open_context(rreq->netfs_priv);
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from fscache
> > > - */
> > > -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> > > {
> > > - int ret;
> > > + return fscache_begin_read_operation(&rreq->cache_resources,
> > > + netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
> > > +}
> > >
> > > - trace_nfs_fscache_read_page(inode, page);
> > > - if (PageChecked(page)) {
> > > - ClearPageChecked(page);
> > > - ret = 1;
> > > - goto out;
> > > - }
> > > +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> > > +{
> > > + struct nfs_netfs_io_data *netfs;
> > > +
> > > + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> > > + if (!netfs)
> > > + return NULL;
> > > + netfs->sreq = sreq;
> > > + refcount_set(&netfs->refcount, 1);
> > > + spin_lock_init(&netfs->lock);
> > > + return netfs;
> > > +}
> > >
> > > - ret = fscache_fallback_read_page(inode, page);
> > > - if (ret < 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> > > - SetPageChecked(page);
> > > - goto out;
> > > +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> > > +{
> > > + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> > > +
> > > + sreq->len = min(sreq->len, rsize);
> > > + return true;
> > > +}
> > > +
> > > +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> > > +{
> > > + struct nfs_pageio_descriptor pgio;
> > > + struct inode *inode = sreq->rreq->inode;
> > > + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> > > + struct page *page;
> > > + int err;
> > > + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> > > + pgoff_t last = ((sreq->start + sreq->len -
> > > + sreq->transferred - 1) >> PAGE_SHIFT);
> > > + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> > > +
> > > + nfs_pageio_init_read(&pgio, inode, false,
> > > + &nfs_async_read_completion_ops);
> > > +
> > > + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> > > + if (!pgio.pg_netfs)
> > > + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> > > +
> > > + xas_lock(&xas);
> > > + xas_for_each(&xas, page, last) {
> > > + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> > > + xas_pause(&xas);
> > > + xas_unlock(&xas);
> > > + err = nfs_pageio_add_page(&pgio, ctx, page);
> > > + if (err < 0)
> > > + return netfs_subreq_terminated(sreq, err, false);
> > > + xas_lock(&xas);
> > > }
> > > + xas_unlock(&xas);
> > > + nfs_pageio_complete_read(&pgio);
> > > + nfs_netfs_put(pgio.pg_netfs);
> > > +}
> > >
> > > - /* Read completed synchronously */
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> > > - SetPageUptodate(page);
> > > - ret = 0;
> > > -out:
> > > - trace_nfs_fscache_read_page_exit(inode, page, ret);
> > > - return ret;
> > > +void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > +
> > > + if (!netfs)
> > > + return;
> > > +
> > > + spin_lock(&netfs->lock);
> > > + atomic_inc(&netfs->rpcs);
> > > + netfs->rpc_byte_count += hdr->args.count;
> > > + spin_unlock(&netfs->lock);
> > > }
> > >
> > > -/*
> > > - * Store a newly fetched page in fscache. We can be certain there's no page
> > > - * stored in the cache as yet otherwise we would've read it from there.
> > > - */
> > > -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> > > +void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
> > > {
> > > - int ret;
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > >
> > > - trace_nfs_fscache_write_page(inode, page);
> > > + if (!netfs)
> > > + return;
> > > +
> > > + spin_lock(&netfs->lock);
> > > + if (hdr->res.op_status) {
> > > + /*
> > > + * Retryable errors such as BAD_STATEID will be re-issued,
> > > + * so reduce the bytes and the RPC counts.
> > > + */
> > > + netfs->rpc_byte_count -= hdr->args.count;
> > > + atomic_dec(&netfs->rpcs);
> > > + }
> > > + spin_unlock(&netfs->lock);
> > > +}
> > > +
> > > +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + if (!netfs)
> > > + return;
> > >
> > > - ret = fscache_fallback_write_page(inode, page, true);
> > > + sreq = netfs->sreq;
> > > + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> > > + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
> > >
> > > - if (ret != 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > - } else {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> > > + spin_lock(&netfs->lock);
> > > + if (hdr->error)
> > > + netfs->error = hdr->error;
> > > + else
> > > + netfs->transferred += hdr->res.count;
> > > + spin_unlock(&netfs->lock);
> > > +
> > > + /* Only the last RPC completion should call netfs_subreq_terminated() */
> > > + if (atomic_dec_and_test(&netfs->rpcs) &&
> > > + (netfs->rpc_byte_count >= sreq->len)) {
> >
> > I don't quite understand the point of the rpc_byte_count. I guess this
> > starts out being a total of the requested bytes in the read, and we
> > decrement the number of bytes in the replies.
> >
> > This should always be a value that is equal to or larger than the
> > sreq->len. Why is it necessary to track that, instead of just the number
> > of RPCs?
> >
>
> As far as I know there's nothing stopping the count of RPCs from going to 0
> before you end up sending all the RPCs.
>
> Example: Suppose for a single netfs subreq you can get two NFS
> RPCs that both need to complete before the netfs subreq completes.
> As far as I know you could get the scenario of:
> send RPC1 (rpcs == 1)
> receive RPC1 (rpcs == 0)
> send RPC2
> receive RPC2
>
>
I thought of an alternative to the rpc_byte_count but did not implement it.
I'm pretty sure I could have a flag that indicated all RPCs had been sent,
and set this at the bottom of nfs_netfs_issue_read(). Then the logic gating
the call to netfs_subreq_terminated() would become:
if ((netfs->all_rpcs_sent && atomic_dec_and_test(&netfs->rpcs))
Would that be clearer/cleaner?
>
> > > + netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
> > > + nfs_netfs_put(netfs);
> > > + hdr->netfs = NULL;
> > > }
> > > - trace_nfs_fscache_write_page_exit(inode, page, ret);
> > > }
> > > +
> > > +const struct netfs_request_ops nfs_netfs_ops = {
> > > + .init_request = nfs_netfs_init_request,
> > > + .free_request = nfs_netfs_free_request,
> > > + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> > > + .issue_read = nfs_netfs_issue_read,
> > > + .clamp_length = nfs_netfs_clamp_length
> > > +};
> > > diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> > > index 38614ed8f951..c59a82a7d4a8 100644
> > > --- a/fs/nfs/fscache.h
> > > +++ b/fs/nfs/fscache.h
> > > @@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
> > > u64 change_attr;
> > > };
> > >
> > > +struct nfs_netfs_io_data {
> > > + refcount_t refcount;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + /*
> > > + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> > > + * with their own read completion. In netfs, we can only call
> > > + * netfs_subreq_terminated() once for each subrequest. So we
> > > + * must keep track of the rpcs and rpc_byte_count for what has
> > > + * been submitted, and only call netfs via netfs_subreq_terminated()
> > > + * when the final RPC has completed.
> > > + */
> > > + atomic_t rpcs;
> > > + unsigned long rpc_byte_count;
> > > +
> > > + /*
> > > + * Final dispostion of the netfs_io_subrequest, sent in
> > > + * netfs_subreq_terminated()
> > > + */
> > > + spinlock_t lock;
> > > + ssize_t transferred;
> > > + int error;
> > > +};
> > > +
> > > +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + refcount_inc(&netfs->refcount);
> > > +}
> > > +
> > > +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + if (refcount_dec_and_test(&netfs->refcount))
> > > + kfree(netfs);
> > > +}
> > > +extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> > > +
> > > /*
> > > * fscache.c
> > > */
> > > @@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
> > > extern void nfs_fscache_open_file(struct inode *, struct file *);
> > > extern void nfs_fscache_release_file(struct inode *, struct file *);
> > >
> > > -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> > > -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> > > -
> > > static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > {
> > > if (folio_test_fscache(folio)) {
> > > if (current_is_kswapd() || !(gfp & __GFP_FS))
> > > return false;
> > > folio_wait_fscache(folio);
> > > - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > - nfs_inc_fscache_stats(folio->mapping->host,
> > > - NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > }
> > > + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > return true;
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from an inode data storage object.
> > > - */
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - return __nfs_fscache_read_page(inode, page);
> > > - return -ENOBUFS;
> > > -}
> > > -
> > > -/*
> > > - * Store a page newly fetched from the server in an inode data storage object
> > > - * in the cache.
> > > - */
> > > -static inline void nfs_fscache_write_page(struct inode *inode,
> > > - struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - __nfs_fscache_write_page(inode, page);
> > > -}
> > > -
> > > static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> > > struct inode *inode)
> > > {
> > > @@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > {
> > > return true; /* may release folio */
> > > }
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > -{
> > > - return -ENOBUFS;
> > > -}
> > > -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> > > static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
> > >
> > > static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> > > index aa2aec785ab5..a0af3518d8db 100644
> > > --- a/fs/nfs/inode.c
> > > +++ b/fs/nfs/inode.c
> > > @@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> > > #endif /* CONFIG_NFS_V4 */
> > > #ifdef CONFIG_NFS_V4_2
> > > nfsi->xattr_cache = NULL;
> > > +#endif
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> > > #endif
> > > return VFS_I(nfsi);
> > > }
> > > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > > index 273687082992..e5589036c1f8 100644
> > > --- a/fs/nfs/internal.h
> > > +++ b/fs/nfs/internal.h
> > > @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> > > extern int nfs_client_for_each_server(struct nfs_client *clp,
> > > int (*fn)(struct nfs_server *, void *),
> > > void *data);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > +extern const struct netfs_request_ops nfs_netfs_ops;
> > > +#endif
> > > +
> > > /* io.c */
> > > extern void nfs_start_io_read(struct inode *inode);
> > > extern void nfs_end_io_read(struct inode *inode);
> > > @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
> > >
> > > struct nfs_pgio_completion_ops;
> > > /* read.c */
> > > +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > struct inode *inode, bool force_mds,
> > > const struct nfs_pgio_completion_ops *compl_ops);
> > > +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > + struct nfs_open_context *ctx,
> > > + struct page *page);
> > > +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> > > extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> > > extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
> > >
> > > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> > > index 317cedfa52bf..600989332a6f 100644
> > > --- a/fs/nfs/pagelist.c
> > > +++ b/fs/nfs/pagelist.c
> > > @@ -25,6 +25,7 @@
> > > #include "internal.h"
> > > #include "pnfs.h"
> > > #include "nfstrace.h"
> > > +#include "fscache.h"
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > @@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> > > hdr->good_bytes = mirror->pg_count;
> > > hdr->io_completion = desc->pg_io_completion;
> > > hdr->dreq = desc->pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (desc->pg_netfs) {
> > > + hdr->netfs = desc->pg_netfs;
> > > + nfs_netfs_get(desc->pg_netfs);
> > > + }
> > > +#endif
> > > hdr->release = release;
> > > hdr->completion_ops = desc->pg_completion_ops;
> > > if (hdr->completion_ops->init_hdr)
> > > @@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> > > desc->pg_lseg = NULL;
> > > desc->pg_io_completion = NULL;
> > > desc->pg_dreq = NULL;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = NULL;
> > > +#endif
> > > desc->pg_bsize = bsize;
> > >
> > > desc->pg_mirror_count = 1;
> > > @@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> > > /* Set up the argument struct */
> > > nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> > > desc->pg_rpc_callops = &nfs_pgio_common_ops;
> > > +
> > > return 0;
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> > > @@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
> > >
> > > desc->pg_io_completion = hdr->io_completion;
> > > desc->pg_dreq = hdr->dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = hdr->netfs;
> > > +#endif
> > > list_splice_init(&hdr->pages, &pages);
> > > while (!list_empty(&pages)) {
> > > struct nfs_page *req = nfs_list_entry(pages.next);
> > > diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> > > index 525e82ea9a9e..3bc48472f207 100644
> > > --- a/fs/nfs/read.c
> > > +++ b/fs/nfs/read.c
> > > @@ -30,7 +30,7 @@
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > static const struct nfs_rw_ops nfs_rw_read_ops;
> > >
> > > static struct kmem_cache *nfs_rdata_cachep;
> > > @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
> > >
> > > -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > {
> > > struct nfs_pgio_mirror *pgm;
> > > unsigned long npages;
> > > @@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
> > >
> > > static void nfs_readpage_release(struct nfs_page *req, int error)
> > > {
> > > - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > struct page *page = req->wb_page;
> > >
> > > - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> > > - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> > > - (long long)req_offset(req));
> > > -
> > > if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> > > SetPageError(page);
> > > if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> > > - if (PageUptodate(page))
> > > - nfs_fscache_write_page(inode, page);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > +
> > > + /*
> > > + * If fscache is enabled, netfs will unlock pages.
> > > + * Otherwise, we have to unlock the page here
> > > + */
> > > + if (!netfs_inode(inode)->cache)
> > > + unlock_page(page);
> > > +#else
> > > unlock_page(page);
> > > +#endif
> > > }
> > > +
> > > nfs_release_request(req);
> > > }
> > >
> > > @@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> > > nfs_list_remove_request(req);
> > > nfs_readpage_release(req, error);
> > > }
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_completion(hdr);
> > > +#endif
> > > +
> > > out:
> > > hdr->release(hdr);
> > > }
> > > @@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> > > struct rpc_task_setup *task_setup_data, int how)
> > > {
> > > rpc_ops->read_setup(hdr, msg);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_initiate(hdr);
> > > +#endif
> > > trace_nfs_initiate_read(hdr);
> > > }
> > >
> > > @@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
> > > }
> > > }
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > .error_cleanup = nfs_async_read_error,
> > > .completion = nfs_read_completion,
> > > };
> > > @@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
> > > if (status != 0)
> > > return status;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_done(hdr);
> > > +#endif
> > > nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> > > trace_nfs_readpage_done(task, hdr);
> > >
> > > @@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > >
> > > aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
> > >
> > > - if (!IS_SYNC(page->mapping->host)) {
> > > - error = nfs_fscache_read_page(page->mapping->host, page);
> > > - if (error == 0)
> > > - goto out_unlock;
> > > - }
> > > -
> > > new = nfs_create_request(ctx, page, 0, aligned_len);
> > > if (IS_ERR(new))
> > > goto out_error;
> > > @@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > return 0;
> > > out_error:
> > > error = PTR_ERR(new);
> > > -out_unlock:
> > > - unlock_page(page);
> > > out:
> > > return error;
> > > }
> > > @@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (NFS_STALE(inode))
> > > goto out_unlock;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (netfs_inode(inode)->cache) {
> > > + ret = netfs_read_folio(file, folio);
> > > + goto out;
> > > + }
> > > +#endif
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > @@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > &nfs_async_read_completion_ops);
> > >
> > > ret = nfs_pageio_add_page(&pgio, ctx, page);
> > > - if (ret)
> > > - goto out;
> > > + if (ret) {
> > > + put_nfs_open_context(ctx);
> > > + goto out_unlock;
> > > + }
> > >
> > > nfs_pageio_complete_read(&pgio);
> > > ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> > > @@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (!PageUptodate(page) && !ret)
> > > ret = xchg(&ctx->error, 0);
> > > }
> > > -out:
> > > put_nfs_open_context(ctx);
> > > - trace_nfs_aop_readpage_done(inode, page, ret);
> > > - return ret;
> > > + goto out;
> > > +
> > > out_unlock:
> > > unlock_page(page);
> > > +out:
> > > trace_nfs_aop_readpage_done(inode, page, ret);
> > > return ret;
> > > }
> > > @@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
> > > if (NFS_STALE(inode))
> > > goto out;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (netfs_inode(inode)->cache) {
> > > + netfs_readahead(ractl);
> > > + ret = 0;
> > > + goto out;
> > > + }
> > > +#endif
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> > > index ba7e2e4b0926..8eeb16d9bacd 100644
> > > --- a/include/linux/nfs_page.h
> > > +++ b/include/linux/nfs_page.h
> > > @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> > > struct pnfs_layout_segment *pg_lseg;
> > > struct nfs_io_completion *pg_io_completion;
> > > struct nfs_direct_req *pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *pg_netfs;
> > > +#endif
> > > unsigned int pg_bsize; /* default bsize for mirrors */
> > >
> > > u32 pg_mirror_count;
> > > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > > index e86cf6642d21..e196ef595908 100644
> > > --- a/include/linux/nfs_xdr.h
> > > +++ b/include/linux/nfs_xdr.h
> > > @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> > > const struct nfs_rw_ops *rw_ops;
> > > struct nfs_io_completion *io_completion;
> > > struct nfs_direct_req *dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *netfs;
> > > +#endif
> > >
> > > int pnfs_error;
> > > int error; /* merge with pnfs_error */
> >
> > --
> > Jeff Layton <[email protected]>
> >
On Thu, 2022-09-01 at 09:38 -0400, David Wysochanski wrote:
> On Thu, Sep 1, 2022 at 8:45 AM Jeff Layton <[email protected]> wrote:
> >
> > On Wed, 2022-08-31 at 20:48 -0400, Dave Wysochanski wrote:
> > > Convert the NFS buffered read code paths to corresponding netfs APIs,
> > > but only when fscache is configured and enabled.
> > >
> > > The netfs API defines struct netfs_request_ops which must be filled
> > > in by the network filesystem. For NFS, we only need to define 5 of
> > > the functions, the main one being the issue_read() function.
> > > The issue_read() function is called by the netfs layer when a read
> > > cannot be fulfilled locally, and must be sent to the server (either
> > > the cache is not active, or it is active but the data is not available).
> > > Once the read from the server is complete, netfs requires a call to
> > > netfs_subreq_terminated() which conveys either how many bytes were read
> > > successfully, or an error. Note that issue_read() is called with a
> > > structure, netfs_io_subrequest, which defines the IO requested, and
> > > contains a start and a length (both in bytes), and assumes the underlying
> > > netfs will return a either an error on the whole region, or the number
> > > of bytes successfully read.
> > >
> > > The NFS IO path is page based and the main APIs are the pgio APIs defined
> > > in pagelist.c. For the pgio APIs, there is no way for the caller to
> > > know how many RPCs will be sent and how the pages will be broken up
> > > into underlying RPCs, each of which will have their own return code.
> > > Thus, NFS needs some way to accommodate the netfs API requirement on
> > > the single response to the whole request, while also minimizing
> > > disruptive changes to the NFS pgio layer. The approach taken with this
> > > patch is to allocate a small structure for each call to nfs_issue_read()
> > > to keep some accounting information for the outstanding RPCs, as well as
> > > the final error value or the number of bytes successfully read. The
> > > accounting data is updated inside nfs_netfs_read_initiate(), and
> > > nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> > > to the data. Then finally in nfs_read_completion(), call into
> > > nfs_netfs_read_completion() to update the final error value and bytes
> > > read, and check the accounting data to determine whether this is the
> > > final RPC completion. If this is the last RPC, then call into
> > > netfs_subreq_terminated() with the final error value or the number
> > > of bytes transferred.
> > >
> > > Link: https://lore.kernel.org/linux-nfs/[email protected]/
> > >
> > > Signed-off-by: Dave Wysochanski <[email protected]>
> > > ---
> > > fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
> > > fs/nfs/fscache.h | 71 +++++++------
> > > fs/nfs/inode.c | 3 +
> > > fs/nfs/internal.h | 9 ++
> > > fs/nfs/pagelist.c | 14 +++
> > > fs/nfs/read.c | 68 ++++++++----
> > > include/linux/nfs_page.h | 3 +
> > > include/linux/nfs_xdr.h | 3 +
> > > 8 files changed, 245 insertions(+), 145 deletions(-)
> > >
> > > diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> > > index a6fc1c8b6644..85f8251a608a 100644
> > > --- a/fs/nfs/fscache.c
> > > +++ b/fs/nfs/fscache.c
> > > @@ -15,6 +15,9 @@
> > > #include <linux/seq_file.h>
> > > #include <linux/slab.h>
> > > #include <linux/iversion.h>
> > > +#include <linux/xarray.h>
> > > +#include <linux/fscache.h>
> > > +#include <linux/netfs.h>
> > >
> > > #include "internal.h"
> > > #include "iostat.h"
> > > @@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> > > fscache_unuse_cookie(cookie, &auxdata, &i_size);
> > > }
> > >
> > > -/*
> > > - * Fallback page reading interface.
> > > - */
> > > -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> > > +
> > > +atomic_t nfs_netfs_debug_id;
> > > +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_read_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> > > - NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> > > +
> > > + if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
> > > + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> > > +
> > > + return 0;
> > > }
> > >
> > > -/*
> > > - * Fallback page writing interface.
> > > - */
> > > -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> > > - bool no_space_allocated_yet)
> > > +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> > > {
> > > - struct netfs_cache_resources cres;
> > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > - struct iov_iter iter;
> > > - struct bio_vec bvec[1];
> > > - loff_t start = page_offset(page);
> > > - size_t len = PAGE_SIZE;
> > > - int ret;
> > > -
> > > - memset(&cres, 0, sizeof(cres));
> > > - bvec[0].bv_page = page;
> > > - bvec[0].bv_offset = 0;
> > > - bvec[0].bv_len = PAGE_SIZE;
> > > - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > -
> > > - ret = fscache_begin_write_operation(&cres, cookie);
> > > - if (ret < 0)
> > > - return ret;
> > > -
> > > - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> > > - no_space_allocated_yet);
> > > - if (ret == 0)
> > > - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> > > - fscache_end_operation(&cres);
> > > - return ret;
> > > + put_nfs_open_context(rreq->netfs_priv);
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from fscache
> > > - */
> > > -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> > > {
> > > - int ret;
> > > + return fscache_begin_read_operation(&rreq->cache_resources,
> > > + netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
> > > +}
> > >
> > > - trace_nfs_fscache_read_page(inode, page);
> > > - if (PageChecked(page)) {
> > > - ClearPageChecked(page);
> > > - ret = 1;
> > > - goto out;
> > > - }
> > > +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> > > +{
> > > + struct nfs_netfs_io_data *netfs;
> > > +
> > > + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> > > + if (!netfs)
> > > + return NULL;
> > > + netfs->sreq = sreq;
> > > + refcount_set(&netfs->refcount, 1);
> > > + spin_lock_init(&netfs->lock);
> > > + return netfs;
> > > +}
> > >
> > > - ret = fscache_fallback_read_page(inode, page);
> > > - if (ret < 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> > > - SetPageChecked(page);
> > > - goto out;
> > > +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> > > +{
> > > + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> > > +
> > > + sreq->len = min(sreq->len, rsize);
> > > + return true;
> > > +}
> > > +
> > > +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> > > +{
> > > + struct nfs_pageio_descriptor pgio;
> > > + struct inode *inode = sreq->rreq->inode;
> > > + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> > > + struct page *page;
> > > + int err;
> > > + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> > > + pgoff_t last = ((sreq->start + sreq->len -
> > > + sreq->transferred - 1) >> PAGE_SHIFT);
> > > + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> > > +
> > > + nfs_pageio_init_read(&pgio, inode, false,
> > > + &nfs_async_read_completion_ops);
> > > +
> > > + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> > > + if (!pgio.pg_netfs)
> > > + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> > > +
> > > + xas_lock(&xas);
> > > + xas_for_each(&xas, page, last) {
> > > + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> > > + xas_pause(&xas);
> > > + xas_unlock(&xas);
> > > + err = nfs_pageio_add_page(&pgio, ctx, page);
> > > + if (err < 0)
> > > + return netfs_subreq_terminated(sreq, err, false);
> > > + xas_lock(&xas);
> > > }
> > > + xas_unlock(&xas);
> > > + nfs_pageio_complete_read(&pgio);
> > > + nfs_netfs_put(pgio.pg_netfs);
> > > +}
> > >
> > > - /* Read completed synchronously */
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> > > - SetPageUptodate(page);
> > > - ret = 0;
> > > -out:
> > > - trace_nfs_fscache_read_page_exit(inode, page, ret);
> > > - return ret;
> > > +void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > +
> > > + if (!netfs)
> > > + return;
> > > +
> > > + spin_lock(&netfs->lock);
> > > + atomic_inc(&netfs->rpcs);
> > > + netfs->rpc_byte_count += hdr->args.count;
> > > + spin_unlock(&netfs->lock);
> > > }
> > >
> > > -/*
> > > - * Store a newly fetched page in fscache. We can be certain there's no page
> > > - * stored in the cache as yet otherwise we would've read it from there.
> > > - */
> > > -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> > > +void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
> > > {
> > > - int ret;
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > >
> > > - trace_nfs_fscache_write_page(inode, page);
> > > + if (!netfs)
> > > + return;
> > > +
> > > + spin_lock(&netfs->lock);
> > > + if (hdr->res.op_status) {
> > > + /*
> > > + * Retryable errors such as BAD_STATEID will be re-issued,
> > > + * so reduce the bytes and the RPC counts.
> > > + */
> > > + netfs->rpc_byte_count -= hdr->args.count;
> > > + atomic_dec(&netfs->rpcs);
> > > + }
> > > + spin_unlock(&netfs->lock);
> > > +}
> > > +
> > > +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> > > +{
> > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + if (!netfs)
> > > + return;
> > >
> > > - ret = fscache_fallback_write_page(inode, page, true);
> > > + sreq = netfs->sreq;
> > > + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> > > + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
> > >
> > > - if (ret != 0) {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > - } else {
> > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> > > + spin_lock(&netfs->lock);
> > > + if (hdr->error)
> > > + netfs->error = hdr->error;
> > > + else
> > > + netfs->transferred += hdr->res.count;
> > > + spin_unlock(&netfs->lock);
> > > +
> > > + /* Only the last RPC completion should call netfs_subreq_terminated() */
> > > + if (atomic_dec_and_test(&netfs->rpcs) &&
> > > + (netfs->rpc_byte_count >= sreq->len)) {
> >
> > I don't quite understand the point of the rpc_byte_count. I guess this
> > starts out being a total of the requested bytes in the read, and we
> > decrement the number of bytes in the replies.
> >
> > This should always be a value that is equal to or larger than the
> > sreq->len. Why is it necessary to track that, instead of just the number
> > of RPCs?
> >
>
> As far as I know there's nothing stopping the count of RPCs from going to 0
> before you end up sending all the RPCs.
>
> Example: Suppose for a single netfs subreq you can get two NFS
> RPCs that both need to complete before the netfs subreq completes.
> As far as I know you could get the scenario of:
> send RPC1 (rpcs == 1)
> receive RPC1 (rpcs == 0)
> send RPC2
> receive RPC2
>
Ok, I get it now, thanks.
Why does rpcs need to be atomic_t but rpc_byte_count doesn't? I'd move
all of that handling inside the netfs->lock instead of bothering with
atomic_t there. Still, that scheme seems a bit complex.
Would it be possible to have the netfs refcount drive this? Make it so
that when the last reference to the netfs object is put, that you call
netfs_subreq_terminated and then free it. That could eliminate a couple
of fields in nfs_netfs_io_data too. Fewer moving parts is better.
You already hold an extra reference to "netfs" all the way through to
the end of issue_read. I *think* by then, all of the initial sends
should be done, no? If so, then you needn't worry about the race above.
> > > + netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
> > > + nfs_netfs_put(netfs);
> > > + hdr->netfs = NULL;
> > > }
> > > - trace_nfs_fscache_write_page_exit(inode, page, ret);
> > > }
> > > +
> > > +const struct netfs_request_ops nfs_netfs_ops = {
> > > + .init_request = nfs_netfs_init_request,
> > > + .free_request = nfs_netfs_free_request,
> > > + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> > > + .issue_read = nfs_netfs_issue_read,
> > > + .clamp_length = nfs_netfs_clamp_length
> > > +};
> > > diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> > > index 38614ed8f951..c59a82a7d4a8 100644
> > > --- a/fs/nfs/fscache.h
> > > +++ b/fs/nfs/fscache.h
> > > @@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
> > > u64 change_attr;
> > > };
> > >
> > > +struct nfs_netfs_io_data {
> > > + refcount_t refcount;
> > > + struct netfs_io_subrequest *sreq;
> > > +
> > > + /*
> > > + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> > > + * with their own read completion. In netfs, we can only call
> > > + * netfs_subreq_terminated() once for each subrequest. So we
> > > + * must keep track of the rpcs and rpc_byte_count for what has
> > > + * been submitted, and only call netfs via netfs_subreq_terminated()
> > > + * when the final RPC has completed.
> > > + */
> > > + atomic_t rpcs;
> > > + unsigned long rpc_byte_count;
> > > +
> > > + /*
> > > + * Final dispostion of the netfs_io_subrequest, sent in
> > > + * netfs_subreq_terminated()
> > > + */
> > > + spinlock_t lock;
> > > + ssize_t transferred;
> > > + int error;
> > > +};
> > > +
> > > +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + refcount_inc(&netfs->refcount);
> > > +}
> > > +
> > > +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> > > +{
> > > + if (refcount_dec_and_test(&netfs->refcount))
> > > + kfree(netfs);
> > > +}
> > > +extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
> > > +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> > > +
> > > /*
> > > * fscache.c
> > > */
> > > @@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
> > > extern void nfs_fscache_open_file(struct inode *, struct file *);
> > > extern void nfs_fscache_release_file(struct inode *, struct file *);
> > >
> > > -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> > > -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> > > -
> > > static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > {
> > > if (folio_test_fscache(folio)) {
> > > if (current_is_kswapd() || !(gfp & __GFP_FS))
> > > return false;
> > > folio_wait_fscache(folio);
> > > - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > - nfs_inc_fscache_stats(folio->mapping->host,
> > > - NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > }
> > > + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > return true;
> > > }
> > >
> > > -/*
> > > - * Retrieve a page from an inode data storage object.
> > > - */
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - return __nfs_fscache_read_page(inode, page);
> > > - return -ENOBUFS;
> > > -}
> > > -
> > > -/*
> > > - * Store a page newly fetched from the server in an inode data storage object
> > > - * in the cache.
> > > - */
> > > -static inline void nfs_fscache_write_page(struct inode *inode,
> > > - struct page *page)
> > > -{
> > > - if (netfs_inode(inode)->cache)
> > > - __nfs_fscache_write_page(inode, page);
> > > -}
> > > -
> > > static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> > > struct inode *inode)
> > > {
> > > @@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > {
> > > return true; /* may release folio */
> > > }
> > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > -{
> > > - return -ENOBUFS;
> > > -}
> > > -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> > > static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
> > >
> > > static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> > > index aa2aec785ab5..a0af3518d8db 100644
> > > --- a/fs/nfs/inode.c
> > > +++ b/fs/nfs/inode.c
> > > @@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> > > #endif /* CONFIG_NFS_V4 */
> > > #ifdef CONFIG_NFS_V4_2
> > > nfsi->xattr_cache = NULL;
> > > +#endif
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> > > #endif
Maybe make a nfs_netfs_init_init that compiles out when
CONFIG_NFS_FSCACHE isn't defined. Some ifdef'ery is OK, but it's nice to
avoid littering the code with it if you can.
> > > return VFS_I(nfsi);
> > > }
> > > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > > index 273687082992..e5589036c1f8 100644
> > > --- a/fs/nfs/internal.h
> > > +++ b/fs/nfs/internal.h
> > > @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> > > extern int nfs_client_for_each_server(struct nfs_client *clp,
> > > int (*fn)(struct nfs_server *, void *),
> > > void *data);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > +extern const struct netfs_request_ops nfs_netfs_ops;
> > > +#endif
> > > +
> > > /* io.c */
> > > extern void nfs_start_io_read(struct inode *inode);
> > > extern void nfs_end_io_read(struct inode *inode);
> > > @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
> > >
> > > struct nfs_pgio_completion_ops;
> > > /* read.c */
> > > +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > struct inode *inode, bool force_mds,
> > > const struct nfs_pgio_completion_ops *compl_ops);
> > > +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > + struct nfs_open_context *ctx,
> > > + struct page *page);
> > > +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> > > extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> > > extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
> > >
> > > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> > > index 317cedfa52bf..600989332a6f 100644
> > > --- a/fs/nfs/pagelist.c
> > > +++ b/fs/nfs/pagelist.c
> > > @@ -25,6 +25,7 @@
> > > #include "internal.h"
> > > #include "pnfs.h"
> > > #include "nfstrace.h"
> > > +#include "fscache.h"
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > @@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> > > hdr->good_bytes = mirror->pg_count;
> > > hdr->io_completion = desc->pg_io_completion;
> > > hdr->dreq = desc->pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (desc->pg_netfs) {
> > > + hdr->netfs = desc->pg_netfs;
> > > + nfs_netfs_get(desc->pg_netfs);
> > > + }
> > > +#endif
> > > hdr->release = release;
> > > hdr->completion_ops = desc->pg_completion_ops;
> > > if (hdr->completion_ops->init_hdr)
> > > @@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> > > desc->pg_lseg = NULL;
> > > desc->pg_io_completion = NULL;
> > > desc->pg_dreq = NULL;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = NULL;
> > > +#endif
> > > desc->pg_bsize = bsize;
> > >
> > > desc->pg_mirror_count = 1;
> > > @@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> > > /* Set up the argument struct */
> > > nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> > > desc->pg_rpc_callops = &nfs_pgio_common_ops;
> > > +
> > > return 0;
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> > > @@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
> > >
> > > desc->pg_io_completion = hdr->io_completion;
> > > desc->pg_dreq = hdr->dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + desc->pg_netfs = hdr->netfs;
> > > +#endif
> > > list_splice_init(&hdr->pages, &pages);
> > > while (!list_empty(&pages)) {
> > > struct nfs_page *req = nfs_list_entry(pages.next);
> > > diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> > > index 525e82ea9a9e..3bc48472f207 100644
> > > --- a/fs/nfs/read.c
> > > +++ b/fs/nfs/read.c
> > > @@ -30,7 +30,7 @@
> > >
> > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > static const struct nfs_rw_ops nfs_rw_read_ops;
> > >
> > > static struct kmem_cache *nfs_rdata_cachep;
> > > @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > }
> > > EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
> > >
> > > -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > {
> > > struct nfs_pgio_mirror *pgm;
> > > unsigned long npages;
> > > @@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
> > >
> > > static void nfs_readpage_release(struct nfs_page *req, int error)
> > > {
> > > - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > struct page *page = req->wb_page;
> > >
> > > - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> > > - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> > > - (long long)req_offset(req));
> > > -
> > > if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> > > SetPageError(page);
> > > if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> > > - if (PageUptodate(page))
> > > - nfs_fscache_write_page(inode, page);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > +
> > > + /*
> > > + * If fscache is enabled, netfs will unlock pages.
> > > + * Otherwise, we have to unlock the page here
> > > + */
> > > + if (!netfs_inode(inode)->cache)
> > > + unlock_page(page);
> > > +#else
> > > unlock_page(page);
> > > +#endif
This would look nicer in a little helper that compiles away to a no-op
when fscache isn't compiled in.
> > > }
> > > +
> > > nfs_release_request(req);
> > > }
> > >
> > > @@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> > > nfs_list_remove_request(req);
> > > nfs_readpage_release(req, error);
> > > }
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_completion(hdr);
> > > +#endif
Instead of doing this, fix it so that this is a no-op when
CONFIG_NFS_FSCACHE isn't defined.
> > > +
> > > out:
> > > hdr->release(hdr);
> > > }
> > > @@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> > > struct rpc_task_setup *task_setup_data, int how)
> > > {
> > > rpc_ops->read_setup(hdr, msg);
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_initiate(hdr);
> > > +#endif
...and here.
> > > trace_nfs_initiate_read(hdr);
> > > }
> > >
> > > @@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
> > > }
> > > }
> > >
> > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > .error_cleanup = nfs_async_read_error,
> > > .completion = nfs_read_completion,
> > > };
> > > @@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
> > > if (status != 0)
> > > return status;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + nfs_netfs_read_done(hdr);
> > > +#endif
...and here.
> > > nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> > > trace_nfs_readpage_done(task, hdr);
> > >
> > > @@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > >
> > > aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
> > >
> > > - if (!IS_SYNC(page->mapping->host)) {
> > > - error = nfs_fscache_read_page(page->mapping->host, page);
> > > - if (error == 0)
> > > - goto out_unlock;
> > > - }
> > > -
> > > new = nfs_create_request(ctx, page, 0, aligned_len);
> > > if (IS_ERR(new))
> > > goto out_error;
> > > @@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > return 0;
> > > out_error:
> > > error = PTR_ERR(new);
> > > -out_unlock:
> > > - unlock_page(page);
> > > out:
> > > return error;
> > > }
> > > @@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (NFS_STALE(inode))
> > > goto out_unlock;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (netfs_inode(inode)->cache) {
> > > + ret = netfs_read_folio(file, folio);
> > > + goto out;
> > > + }
> > > +#endif
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > @@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > &nfs_async_read_completion_ops);
> > >
> > > ret = nfs_pageio_add_page(&pgio, ctx, page);
> > > - if (ret)
> > > - goto out;
> > > + if (ret) {
> > > + put_nfs_open_context(ctx);
> > > + goto out_unlock;
> > > + }
> > >
> > > nfs_pageio_complete_read(&pgio);
> > > ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> > > @@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > if (!PageUptodate(page) && !ret)
> > > ret = xchg(&ctx->error, 0);
> > > }
> > > -out:
> > > put_nfs_open_context(ctx);
> > > - trace_nfs_aop_readpage_done(inode, page, ret);
> > > - return ret;
> > > + goto out;
> > > +
> > > out_unlock:
> > > unlock_page(page);
> > > +out:
> > > trace_nfs_aop_readpage_done(inode, page, ret);
> > > return ret;
> > > }
> > > @@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
> > > if (NFS_STALE(inode))
> > > goto out;
> > >
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + if (netfs_inode(inode)->cache) {
> > > + netfs_readahead(ractl);
> > > + ret = 0;
> > > + goto out;
> > > + }
> > > +#endif
> > > if (file == NULL) {
> > > ret = -EBADF;
> > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> > > index ba7e2e4b0926..8eeb16d9bacd 100644
> > > --- a/include/linux/nfs_page.h
> > > +++ b/include/linux/nfs_page.h
> > > @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> > > struct pnfs_layout_segment *pg_lseg;
> > > struct nfs_io_completion *pg_io_completion;
> > > struct nfs_direct_req *pg_dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *pg_netfs;
> > > +#endif
> > > unsigned int pg_bsize; /* default bsize for mirrors */
> > >
> > > u32 pg_mirror_count;
> > > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > > index e86cf6642d21..e196ef595908 100644
> > > --- a/include/linux/nfs_xdr.h
> > > +++ b/include/linux/nfs_xdr.h
> > > @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> > > const struct nfs_rw_ops *rw_ops;
> > > struct nfs_io_completion *io_completion;
> > > struct nfs_direct_req *dreq;
> > > +#ifdef CONFIG_NFS_FSCACHE
> > > + void *netfs;
> > > +#endif
> > >
> > > int pnfs_error;
> > > int error; /* merge with pnfs_error */
> >
> > --
> > Jeff Layton <[email protected]>
> >
>
--
Jeff Layton <[email protected]>
On Thu, Sep 1, 2022 at 12:04 PM Jeff Layton <[email protected]> wrote:
>
> On Thu, 2022-09-01 at 09:38 -0400, David Wysochanski wrote:
> > On Thu, Sep 1, 2022 at 8:45 AM Jeff Layton <[email protected]> wrote:
> > >
> > > On Wed, 2022-08-31 at 20:48 -0400, Dave Wysochanski wrote:
> > > > Convert the NFS buffered read code paths to corresponding netfs APIs,
> > > > but only when fscache is configured and enabled.
> > > >
> > > > The netfs API defines struct netfs_request_ops which must be filled
> > > > in by the network filesystem. For NFS, we only need to define 5 of
> > > > the functions, the main one being the issue_read() function.
> > > > The issue_read() function is called by the netfs layer when a read
> > > > cannot be fulfilled locally, and must be sent to the server (either
> > > > the cache is not active, or it is active but the data is not available).
> > > > Once the read from the server is complete, netfs requires a call to
> > > > netfs_subreq_terminated() which conveys either how many bytes were read
> > > > successfully, or an error. Note that issue_read() is called with a
> > > > structure, netfs_io_subrequest, which defines the IO requested, and
> > > > contains a start and a length (both in bytes), and assumes the underlying
> > > > netfs will return a either an error on the whole region, or the number
> > > > of bytes successfully read.
> > > >
> > > > The NFS IO path is page based and the main APIs are the pgio APIs defined
> > > > in pagelist.c. For the pgio APIs, there is no way for the caller to
> > > > know how many RPCs will be sent and how the pages will be broken up
> > > > into underlying RPCs, each of which will have their own return code.
> > > > Thus, NFS needs some way to accommodate the netfs API requirement on
> > > > the single response to the whole request, while also minimizing
> > > > disruptive changes to the NFS pgio layer. The approach taken with this
> > > > patch is to allocate a small structure for each call to nfs_issue_read()
> > > > to keep some accounting information for the outstanding RPCs, as well as
> > > > the final error value or the number of bytes successfully read. The
> > > > accounting data is updated inside nfs_netfs_read_initiate(), and
> > > > nfs_netfs_read_done(), when a nfs_pgio_header contains a valid pointer
> > > > to the data. Then finally in nfs_read_completion(), call into
> > > > nfs_netfs_read_completion() to update the final error value and bytes
> > > > read, and check the accounting data to determine whether this is the
> > > > final RPC completion. If this is the last RPC, then call into
> > > > netfs_subreq_terminated() with the final error value or the number
> > > > of bytes transferred.
> > > >
> > > > Link: https://lore.kernel.org/linux-nfs/[email protected]/
> > > >
> > > > Signed-off-by: Dave Wysochanski <[email protected]>
> > > > ---
> > > > fs/nfs/fscache.c | 219 +++++++++++++++++++++++----------------
> > > > fs/nfs/fscache.h | 71 +++++++------
> > > > fs/nfs/inode.c | 3 +
> > > > fs/nfs/internal.h | 9 ++
> > > > fs/nfs/pagelist.c | 14 +++
> > > > fs/nfs/read.c | 68 ++++++++----
> > > > include/linux/nfs_page.h | 3 +
> > > > include/linux/nfs_xdr.h | 3 +
> > > > 8 files changed, 245 insertions(+), 145 deletions(-)
> > > >
> > > > diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> > > > index a6fc1c8b6644..85f8251a608a 100644
> > > > --- a/fs/nfs/fscache.c
> > > > +++ b/fs/nfs/fscache.c
> > > > @@ -15,6 +15,9 @@
> > > > #include <linux/seq_file.h>
> > > > #include <linux/slab.h>
> > > > #include <linux/iversion.h>
> > > > +#include <linux/xarray.h>
> > > > +#include <linux/fscache.h>
> > > > +#include <linux/netfs.h>
> > > >
> > > > #include "internal.h"
> > > > #include "iostat.h"
> > > > @@ -235,112 +238,148 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
> > > > fscache_unuse_cookie(cookie, &auxdata, &i_size);
> > > > }
> > > >
> > > > -/*
> > > > - * Fallback page reading interface.
> > > > - */
> > > > -static int fscache_fallback_read_page(struct inode *inode, struct page *page)
> > > > +
> > > > +atomic_t nfs_netfs_debug_id;
> > > > +static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
> > > > {
> > > > - struct netfs_cache_resources cres;
> > > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > > - struct iov_iter iter;
> > > > - struct bio_vec bvec[1];
> > > > - int ret;
> > > > -
> > > > - memset(&cres, 0, sizeof(cres));
> > > > - bvec[0].bv_page = page;
> > > > - bvec[0].bv_offset = 0;
> > > > - bvec[0].bv_len = PAGE_SIZE;
> > > > - iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > > -
> > > > - ret = fscache_begin_read_operation(&cres, cookie);
> > > > - if (ret < 0)
> > > > - return ret;
> > > > -
> > > > - ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
> > > > - NULL, NULL);
> > > > - fscache_end_operation(&cres);
> > > > - return ret;
> > > > + rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
> > > > +
> > > > + if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
> > > > + rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
> > > > +
> > > > + return 0;
> > > > }
> > > >
> > > > -/*
> > > > - * Fallback page writing interface.
> > > > - */
> > > > -static int fscache_fallback_write_page(struct inode *inode, struct page *page,
> > > > - bool no_space_allocated_yet)
> > > > +static void nfs_netfs_free_request(struct netfs_io_request *rreq)
> > > > {
> > > > - struct netfs_cache_resources cres;
> > > > - struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
> > > > - struct iov_iter iter;
> > > > - struct bio_vec bvec[1];
> > > > - loff_t start = page_offset(page);
> > > > - size_t len = PAGE_SIZE;
> > > > - int ret;
> > > > -
> > > > - memset(&cres, 0, sizeof(cres));
> > > > - bvec[0].bv_page = page;
> > > > - bvec[0].bv_offset = 0;
> > > > - bvec[0].bv_len = PAGE_SIZE;
> > > > - iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
> > > > -
> > > > - ret = fscache_begin_write_operation(&cres, cookie);
> > > > - if (ret < 0)
> > > > - return ret;
> > > > -
> > > > - ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
> > > > - no_space_allocated_yet);
> > > > - if (ret == 0)
> > > > - ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
> > > > - fscache_end_operation(&cres);
> > > > - return ret;
> > > > + put_nfs_open_context(rreq->netfs_priv);
> > > > }
> > > >
> > > > -/*
> > > > - * Retrieve a page from fscache
> > > > - */
> > > > -int __nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > > +static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
> > > > {
> > > > - int ret;
> > > > + return fscache_begin_read_operation(&rreq->cache_resources,
> > > > + netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
> > > > +}
> > > >
> > > > - trace_nfs_fscache_read_page(inode, page);
> > > > - if (PageChecked(page)) {
> > > > - ClearPageChecked(page);
> > > > - ret = 1;
> > > > - goto out;
> > > > - }
> > > > +static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
> > > > +{
> > > > + struct nfs_netfs_io_data *netfs;
> > > > +
> > > > + netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
> > > > + if (!netfs)
> > > > + return NULL;
> > > > + netfs->sreq = sreq;
> > > > + refcount_set(&netfs->refcount, 1);
> > > > + spin_lock_init(&netfs->lock);
> > > > + return netfs;
> > > > +}
> > > >
> > > > - ret = fscache_fallback_read_page(inode, page);
> > > > - if (ret < 0) {
> > > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
> > > > - SetPageChecked(page);
> > > > - goto out;
> > > > +static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
> > > > +{
> > > > + size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
> > > > +
> > > > + sreq->len = min(sreq->len, rsize);
> > > > + return true;
> > > > +}
> > > > +
> > > > +static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
> > > > +{
> > > > + struct nfs_pageio_descriptor pgio;
> > > > + struct inode *inode = sreq->rreq->inode;
> > > > + struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
> > > > + struct page *page;
> > > > + int err;
> > > > + pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
> > > > + pgoff_t last = ((sreq->start + sreq->len -
> > > > + sreq->transferred - 1) >> PAGE_SHIFT);
> > > > + XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
> > > > +
> > > > + nfs_pageio_init_read(&pgio, inode, false,
> > > > + &nfs_async_read_completion_ops);
> > > > +
> > > > + pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
> > > > + if (!pgio.pg_netfs)
> > > > + return netfs_subreq_terminated(sreq, -ENOMEM, false);
> > > > +
> > > > + xas_lock(&xas);
> > > > + xas_for_each(&xas, page, last) {
> > > > + /* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs */
> > > > + xas_pause(&xas);
> > > > + xas_unlock(&xas);
> > > > + err = nfs_pageio_add_page(&pgio, ctx, page);
> > > > + if (err < 0)
> > > > + return netfs_subreq_terminated(sreq, err, false);
> > > > + xas_lock(&xas);
> > > > }
> > > > + xas_unlock(&xas);
> > > > + nfs_pageio_complete_read(&pgio);
> > > > + nfs_netfs_put(pgio.pg_netfs);
> > > > +}
> > > >
> > > > - /* Read completed synchronously */
> > > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
> > > > - SetPageUptodate(page);
> > > > - ret = 0;
> > > > -out:
> > > > - trace_nfs_fscache_read_page_exit(inode, page, ret);
> > > > - return ret;
> > > > +void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr)
> > > > +{
> > > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > > +
> > > > + if (!netfs)
> > > > + return;
> > > > +
> > > > + spin_lock(&netfs->lock);
> > > > + atomic_inc(&netfs->rpcs);
> > > > + netfs->rpc_byte_count += hdr->args.count;
> > > > + spin_unlock(&netfs->lock);
> > > > }
> > > >
> > > > -/*
> > > > - * Store a newly fetched page in fscache. We can be certain there's no page
> > > > - * stored in the cache as yet otherwise we would've read it from there.
> > > > - */
> > > > -void __nfs_fscache_write_page(struct inode *inode, struct page *page)
> > > > +void nfs_netfs_read_done(struct nfs_pgio_header *hdr)
> > > > {
> > > > - int ret;
> > > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > >
> > > > - trace_nfs_fscache_write_page(inode, page);
> > > > + if (!netfs)
> > > > + return;
> > > > +
> > > > + spin_lock(&netfs->lock);
> > > > + if (hdr->res.op_status) {
> > > > + /*
> > > > + * Retryable errors such as BAD_STATEID will be re-issued,
> > > > + * so reduce the bytes and the RPC counts.
> > > > + */
> > > > + netfs->rpc_byte_count -= hdr->args.count;
> > > > + atomic_dec(&netfs->rpcs);
> > > > + }
> > > > + spin_unlock(&netfs->lock);
> > > > +}
> > > > +
> > > > +void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
> > > > +{
> > > > + struct nfs_netfs_io_data *netfs = hdr->netfs;
> > > > + struct netfs_io_subrequest *sreq;
> > > > +
> > > > + if (!netfs)
> > > > + return;
> > > >
> > > > - ret = fscache_fallback_write_page(inode, page, true);
> > > > + sreq = netfs->sreq;
> > > > + if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
> > > > + __set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
> > > >
> > > > - if (ret != 0) {
> > > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
> > > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > > - } else {
> > > > - nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
> > > > + spin_lock(&netfs->lock);
> > > > + if (hdr->error)
> > > > + netfs->error = hdr->error;
> > > > + else
> > > > + netfs->transferred += hdr->res.count;
> > > > + spin_unlock(&netfs->lock);
> > > > +
> > > > + /* Only the last RPC completion should call netfs_subreq_terminated() */
> > > > + if (atomic_dec_and_test(&netfs->rpcs) &&
> > > > + (netfs->rpc_byte_count >= sreq->len)) {
> > >
> > > I don't quite understand the point of the rpc_byte_count. I guess this
> > > starts out being a total of the requested bytes in the read, and we
> > > decrement the number of bytes in the replies.
> > >
> > > This should always be a value that is equal to or larger than the
> > > sreq->len. Why is it necessary to track that, instead of just the number
> > > of RPCs?
> > >
> >
> > As far as I know there's nothing stopping the count of RPCs from going to 0
> > before you end up sending all the RPCs.
> >
> > Example: Suppose for a single netfs subreq you can get two NFS
> > RPCs that both need to complete before the netfs subreq completes.
> > As far as I know you could get the scenario of:
> > send RPC1 (rpcs == 1)
> > receive RPC1 (rpcs == 0)
> > send RPC2
> > receive RPC2
> >
>
> Ok, I get it now, thanks.
>
> Why does rpcs need to be atomic_t but rpc_byte_count doesn't? I'd move
> all of that handling inside the netfs->lock instead of bothering with
> atomic_t there. Still, that scheme seems a bit complex.
>
> Would it be possible to have the netfs refcount drive this? Make it so
> that when the last reference to the netfs object is put, that you call
> netfs_subreq_terminated and then free it. That could eliminate a couple
> of fields in nfs_netfs_io_data too. Fewer moving parts is better.
>
> You already hold an extra reference to "netfs" all the way through to
> the end of issue_read. I *think* by then, all of the initial sends
> should be done, no? If so, then you needn't worry about the race above.
>
Yes I agree this is a much more elegant approach.
I've implemented this and ran some tests and it looks good.
> > > > + netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
> > > > + nfs_netfs_put(netfs);
> > > > + hdr->netfs = NULL;
> > > > }
> > > > - trace_nfs_fscache_write_page_exit(inode, page, ret);
> > > > }
> > > > +
> > > > +const struct netfs_request_ops nfs_netfs_ops = {
> > > > + .init_request = nfs_netfs_init_request,
> > > > + .free_request = nfs_netfs_free_request,
> > > > + .begin_cache_operation = nfs_netfs_begin_cache_operation,
> > > > + .issue_read = nfs_netfs_issue_read,
> > > > + .clamp_length = nfs_netfs_clamp_length
> > > > +};
> > > > diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> > > > index 38614ed8f951..c59a82a7d4a8 100644
> > > > --- a/fs/nfs/fscache.h
> > > > +++ b/fs/nfs/fscache.h
> > > > @@ -34,6 +34,44 @@ struct nfs_fscache_inode_auxdata {
> > > > u64 change_attr;
> > > > };
> > > >
> > > > +struct nfs_netfs_io_data {
> > > > + refcount_t refcount;
> > > > + struct netfs_io_subrequest *sreq;
> > > > +
> > > > + /*
> > > > + * NFS may split a netfs_io_subrequest into multiple RPCs, each
> > > > + * with their own read completion. In netfs, we can only call
> > > > + * netfs_subreq_terminated() once for each subrequest. So we
> > > > + * must keep track of the rpcs and rpc_byte_count for what has
> > > > + * been submitted, and only call netfs via netfs_subreq_terminated()
> > > > + * when the final RPC has completed.
> > > > + */
> > > > + atomic_t rpcs;
> > > > + unsigned long rpc_byte_count;
> > > > +
> > > > + /*
> > > > + * Final dispostion of the netfs_io_subrequest, sent in
> > > > + * netfs_subreq_terminated()
> > > > + */
> > > > + spinlock_t lock;
> > > > + ssize_t transferred;
> > > > + int error;
> > > > +};
> > > > +
> > > > +static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
> > > > +{
> > > > + refcount_inc(&netfs->refcount);
> > > > +}
> > > > +
> > > > +static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
> > > > +{
> > > > + if (refcount_dec_and_test(&netfs->refcount))
> > > > + kfree(netfs);
> > > > +}
> > > > +extern void nfs_netfs_read_initiate(struct nfs_pgio_header *hdr);
> > > > +extern void nfs_netfs_read_done(struct nfs_pgio_header *hdr);
> > > > +extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
> > > > +
> > > > /*
> > > > * fscache.c
> > > > */
> > > > @@ -45,43 +83,17 @@ extern void nfs_fscache_clear_inode(struct inode *);
> > > > extern void nfs_fscache_open_file(struct inode *, struct file *);
> > > > extern void nfs_fscache_release_file(struct inode *, struct file *);
> > > >
> > > > -extern int __nfs_fscache_read_page(struct inode *, struct page *);
> > > > -extern void __nfs_fscache_write_page(struct inode *, struct page *);
> > > > -
> > > > static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > > {
> > > > if (folio_test_fscache(folio)) {
> > > > if (current_is_kswapd() || !(gfp & __GFP_FS))
> > > > return false;
> > > > folio_wait_fscache(folio);
> > > > - fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > > - nfs_inc_fscache_stats(folio->mapping->host,
> > > > - NFSIOS_FSCACHE_PAGES_UNCACHED);
> > > > }
> > > > + fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
> > > > return true;
> > > > }
> > > >
> > > > -/*
> > > > - * Retrieve a page from an inode data storage object.
> > > > - */
> > > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > > -{
> > > > - if (netfs_inode(inode)->cache)
> > > > - return __nfs_fscache_read_page(inode, page);
> > > > - return -ENOBUFS;
> > > > -}
> > > > -
> > > > -/*
> > > > - * Store a page newly fetched from the server in an inode data storage object
> > > > - * in the cache.
> > > > - */
> > > > -static inline void nfs_fscache_write_page(struct inode *inode,
> > > > - struct page *page)
> > > > -{
> > > > - if (netfs_inode(inode)->cache)
> > > > - __nfs_fscache_write_page(inode, page);
> > > > -}
> > > > -
> > > > static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
> > > > struct inode *inode)
> > > > {
> > > > @@ -130,11 +142,6 @@ static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
> > > > {
> > > > return true; /* may release folio */
> > > > }
> > > > -static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
> > > > -{
> > > > - return -ENOBUFS;
> > > > -}
> > > > -static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
> > > > static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
> > > >
> > > > static inline const char *nfs_server_fscache_state(struct nfs_server *server)
> > > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> > > > index aa2aec785ab5..a0af3518d8db 100644
> > > > --- a/fs/nfs/inode.c
> > > > +++ b/fs/nfs/inode.c
> > > > @@ -2248,6 +2248,9 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
> > > > #endif /* CONFIG_NFS_V4 */
> > > > #ifdef CONFIG_NFS_V4_2
> > > > nfsi->xattr_cache = NULL;
> > > > +#endif
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
> > > > #endif
>
> Maybe make a nfs_netfs_init_init that compiles out when
> CONFIG_NFS_FSCACHE isn't defined. Some ifdef'ery is OK, but it's nice to
> avoid littering the code with it if you can.
>
Will do.
> > > > return VFS_I(nfsi);
> > > > }
> > > > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > > > index 273687082992..e5589036c1f8 100644
> > > > --- a/fs/nfs/internal.h
> > > > +++ b/fs/nfs/internal.h
> > > > @@ -453,6 +453,10 @@ extern void nfs_sb_deactive(struct super_block *sb);
> > > > extern int nfs_client_for_each_server(struct nfs_client *clp,
> > > > int (*fn)(struct nfs_server *, void *),
> > > > void *data);
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > +extern const struct netfs_request_ops nfs_netfs_ops;
> > > > +#endif
> > > > +
> > > > /* io.c */
> > > > extern void nfs_start_io_read(struct inode *inode);
> > > > extern void nfs_end_io_read(struct inode *inode);
> > > > @@ -482,9 +486,14 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
> > > >
> > > > struct nfs_pgio_completion_ops;
> > > > /* read.c */
> > > > +extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > > extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > > struct inode *inode, bool force_mds,
> > > > const struct nfs_pgio_completion_ops *compl_ops);
> > > > +extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > > + struct nfs_open_context *ctx,
> > > > + struct page *page);
> > > > +extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
> > > > extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
> > > > extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
> > > >
> > > > diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> > > > index 317cedfa52bf..600989332a6f 100644
> > > > --- a/fs/nfs/pagelist.c
> > > > +++ b/fs/nfs/pagelist.c
> > > > @@ -25,6 +25,7 @@
> > > > #include "internal.h"
> > > > #include "pnfs.h"
> > > > #include "nfstrace.h"
> > > > +#include "fscache.h"
> > > >
> > > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > > >
> > > > @@ -68,6 +69,12 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
> > > > hdr->good_bytes = mirror->pg_count;
> > > > hdr->io_completion = desc->pg_io_completion;
> > > > hdr->dreq = desc->pg_dreq;
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + if (desc->pg_netfs) {
> > > > + hdr->netfs = desc->pg_netfs;
> > > > + nfs_netfs_get(desc->pg_netfs);
> > > > + }
> > > > +#endif
> > > > hdr->release = release;
> > > > hdr->completion_ops = desc->pg_completion_ops;
> > > > if (hdr->completion_ops->init_hdr)
> > > > @@ -846,6 +853,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
> > > > desc->pg_lseg = NULL;
> > > > desc->pg_io_completion = NULL;
> > > > desc->pg_dreq = NULL;
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + desc->pg_netfs = NULL;
> > > > +#endif
> > > > desc->pg_bsize = bsize;
> > > >
> > > > desc->pg_mirror_count = 1;
> > > > @@ -940,6 +950,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> > > > /* Set up the argument struct */
> > > > nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
> > > > desc->pg_rpc_callops = &nfs_pgio_common_ops;
> > > > +
> > > > return 0;
> > > > }
> > > > EXPORT_SYMBOL_GPL(nfs_generic_pgio);
> > > > @@ -1360,6 +1371,9 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
> > > >
> > > > desc->pg_io_completion = hdr->io_completion;
> > > > desc->pg_dreq = hdr->dreq;
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + desc->pg_netfs = hdr->netfs;
> > > > +#endif
> > > > list_splice_init(&hdr->pages, &pages);
> > > > while (!list_empty(&pages)) {
> > > > struct nfs_page *req = nfs_list_entry(pages.next);
> > > > diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> > > > index 525e82ea9a9e..3bc48472f207 100644
> > > > --- a/fs/nfs/read.c
> > > > +++ b/fs/nfs/read.c
> > > > @@ -30,7 +30,7 @@
> > > >
> > > > #define NFSDBG_FACILITY NFSDBG_PAGECACHE
> > > >
> > > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
> > > > static const struct nfs_rw_ops nfs_rw_read_ops;
> > > >
> > > > static struct kmem_cache *nfs_rdata_cachep;
> > > > @@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
> > > > }
> > > > EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
> > > >
> > > > -static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > > +void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
> > > > {
> > > > struct nfs_pgio_mirror *pgm;
> > > > unsigned long npages;
> > > > @@ -110,20 +110,25 @@ EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
> > > >
> > > > static void nfs_readpage_release(struct nfs_page *req, int error)
> > > > {
> > > > - struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > > struct page *page = req->wb_page;
> > > >
> > > > - dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
> > > > - (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
> > > > - (long long)req_offset(req));
> > > > -
> > > > if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
> > > > SetPageError(page);
> > > > if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
> > > > - if (PageUptodate(page))
> > > > - nfs_fscache_write_page(inode, page);
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
> > > > +
> > > > + /*
> > > > + * If fscache is enabled, netfs will unlock pages.
> > > > + * Otherwise, we have to unlock the page here
> > > > + */
> > > > + if (!netfs_inode(inode)->cache)
> > > > + unlock_page(page);
> > > > +#else
> > > > unlock_page(page);
> > > > +#endif
>
> This would look nicer in a little helper that compiles away to a no-op
> when fscache isn't compiled in.
>
Yes, agree. This will be in the next version.
> > > > }
> > > > +
> > > > nfs_release_request(req);
> > > > }
> > > >
> > > > @@ -177,6 +182,10 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
> > > > nfs_list_remove_request(req);
> > > > nfs_readpage_release(req, error);
> > > > }
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + nfs_netfs_read_completion(hdr);
> > > > +#endif
>
> Instead of doing this, fix it so that this is a no-op when
> CONFIG_NFS_FSCACHE isn't defined.
>
Agree, will be in the next version.
> > > > +
> > > > out:
> > > > hdr->release(hdr);
> > > > }
> > > > @@ -187,6 +196,9 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
> > > > struct rpc_task_setup *task_setup_data, int how)
> > > > {
> > > > rpc_ops->read_setup(hdr, msg);
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + nfs_netfs_read_initiate(hdr);
> > > > +#endif
>
> ...and here.
>
Agree, will be in the next version.
> > > > trace_nfs_initiate_read(hdr);
> > > > }
> > > >
> > > > @@ -202,7 +214,7 @@ nfs_async_read_error(struct list_head *head, int error)
> > > > }
> > > > }
> > > >
> > > > -static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > > +const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
> > > > .error_cleanup = nfs_async_read_error,
> > > > .completion = nfs_read_completion,
> > > > };
> > > > @@ -219,6 +231,9 @@ static int nfs_readpage_done(struct rpc_task *task,
> > > > if (status != 0)
> > > > return status;
> > > >
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + nfs_netfs_read_done(hdr);
> > > > +#endif
>
> ...and here.
>
Agree, will be in the next version.
> > > > nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
> > > > trace_nfs_readpage_done(task, hdr);
> > > >
> > > > @@ -294,12 +309,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > >
> > > > aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
> > > >
> > > > - if (!IS_SYNC(page->mapping->host)) {
> > > > - error = nfs_fscache_read_page(page->mapping->host, page);
> > > > - if (error == 0)
> > > > - goto out_unlock;
> > > > - }
> > > > -
> > > > new = nfs_create_request(ctx, page, 0, aligned_len);
> > > > if (IS_ERR(new))
> > > > goto out_error;
> > > > @@ -315,8 +324,6 @@ nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
> > > > return 0;
> > > > out_error:
> > > > error = PTR_ERR(new);
> > > > -out_unlock:
> > > > - unlock_page(page);
> > > > out:
> > > > return error;
> > > > }
> > > > @@ -355,6 +362,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > > if (NFS_STALE(inode))
> > > > goto out_unlock;
> > > >
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + if (netfs_inode(inode)->cache) {
> > > > + ret = netfs_read_folio(file, folio);
> > > > + goto out;
> > > > + }
> > > > +#endif
> > > > if (file == NULL) {
> > > > ret = -EBADF;
> > > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > > @@ -368,8 +381,10 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > > &nfs_async_read_completion_ops);
> > > >
> > > > ret = nfs_pageio_add_page(&pgio, ctx, page);
> > > > - if (ret)
> > > > - goto out;
> > > > + if (ret) {
> > > > + put_nfs_open_context(ctx);
> > > > + goto out_unlock;
> > > > + }
> > > >
> > > > nfs_pageio_complete_read(&pgio);
> > > > ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
> > > > @@ -378,12 +393,12 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> > > > if (!PageUptodate(page) && !ret)
> > > > ret = xchg(&ctx->error, 0);
> > > > }
> > > > -out:
> > > > put_nfs_open_context(ctx);
> > > > - trace_nfs_aop_readpage_done(inode, page, ret);
> > > > - return ret;
> > > > + goto out;
> > > > +
> > > > out_unlock:
> > > > unlock_page(page);
> > > > +out:
> > > > trace_nfs_aop_readpage_done(inode, page, ret);
> > > > return ret;
> > > > }
> > > > @@ -405,6 +420,13 @@ void nfs_readahead(struct readahead_control *ractl)
> > > > if (NFS_STALE(inode))
> > > > goto out;
> > > >
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + if (netfs_inode(inode)->cache) {
> > > > + netfs_readahead(ractl);
> > > > + ret = 0;
> > > > + goto out;
> > > > + }
> > > > +#endif
> > > > if (file == NULL) {
> > > > ret = -EBADF;
> > > > ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> > > > diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> > > > index ba7e2e4b0926..8eeb16d9bacd 100644
> > > > --- a/include/linux/nfs_page.h
> > > > +++ b/include/linux/nfs_page.h
> > > > @@ -101,6 +101,9 @@ struct nfs_pageio_descriptor {
> > > > struct pnfs_layout_segment *pg_lseg;
> > > > struct nfs_io_completion *pg_io_completion;
> > > > struct nfs_direct_req *pg_dreq;
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + void *pg_netfs;
> > > > +#endif
> > > > unsigned int pg_bsize; /* default bsize for mirrors */
> > > >
> > > > u32 pg_mirror_count;
> > > > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > > > index e86cf6642d21..e196ef595908 100644
> > > > --- a/include/linux/nfs_xdr.h
> > > > +++ b/include/linux/nfs_xdr.h
> > > > @@ -1619,6 +1619,9 @@ struct nfs_pgio_header {
> > > > const struct nfs_rw_ops *rw_ops;
> > > > struct nfs_io_completion *io_completion;
> > > > struct nfs_direct_req *dreq;
> > > > +#ifdef CONFIG_NFS_FSCACHE
> > > > + void *netfs;
> > > > +#endif
> > > >
> > > > int pnfs_error;
> > > > int error; /* merge with pnfs_error */
> > >
> > > --
> > > Jeff Layton <[email protected]>
> > >
> >
>
> --
> Jeff Layton <[email protected]>
>