2022-03-13 17:57:53

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH v10 05/26] NFS: Use kzalloc() to avoid initialising the nfs_open_dir_context

From: Trond Myklebust <[email protected]>

Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/dir.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 1dfbd05081ad..379f88b158fb 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -69,18 +69,15 @@ const struct address_space_operations nfs_dir_aops = {
.freepage = nfs_readdir_clear_array,
};

-static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir)
+static struct nfs_open_dir_context *
+alloc_nfs_open_dir_context(struct inode *dir)
{
struct nfs_inode *nfsi = NFS_I(dir);
struct nfs_open_dir_context *ctx;
- ctx = kmalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
if (ctx != NULL) {
- ctx->duped = 0;
ctx->attr_gencount = nfsi->attr_gencount;
- ctx->dir_cookie = 0;
- ctx->dup_cookie = 0;
- ctx->page_index = 0;
- ctx->eof = false;
spin_lock(&dir->i_lock);
if (list_empty(&nfsi->open_files) &&
(nfsi->cache_validity & NFS_INO_DATA_INVAL_DEFER))
--
2.35.1


2022-03-13 19:07:52

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH v10 06/26] NFS: Calculate page offsets algorithmically

From: Trond Myklebust <[email protected]>

Instead of relying on counting the page offsets as we walk through the
page cache, switch to calculating them algorithmically.

Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/dir.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 379f88b158fb..6f0a38db6c37 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -249,17 +249,20 @@ static const char *nfs_readdir_copy_name(const char *name, unsigned int len)
return ret;
}

+static size_t nfs_readdir_array_maxentries(void)
+{
+ return (PAGE_SIZE - sizeof(struct nfs_cache_array)) /
+ sizeof(struct nfs_cache_array_entry);
+}
+
/*
* Check that the next array entry lies entirely within the page bounds
*/
static int nfs_readdir_array_can_expand(struct nfs_cache_array *array)
{
- struct nfs_cache_array_entry *cache_entry;
-
if (array->page_full)
return -ENOSPC;
- cache_entry = &array->array[array->size + 1];
- if ((char *)cache_entry - (char *)array > PAGE_SIZE) {
+ if (array->size == nfs_readdir_array_maxentries()) {
array->page_full = 1;
return -ENOSPC;
}
@@ -318,6 +321,11 @@ static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
return page;
}

+static loff_t nfs_readdir_page_offset(struct page *page)
+{
+ return (loff_t)page->index * (loff_t)nfs_readdir_array_maxentries();
+}
+
static u64 nfs_readdir_page_last_cookie(struct page *page)
{
struct nfs_cache_array *array;
@@ -448,7 +456,7 @@ static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
if (array->array[i].cookie == desc->dir_cookie) {
struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));

- new_pos = desc->current_index + i;
+ new_pos = nfs_readdir_page_offset(desc->page) + i;
if (desc->attr_gencount != nfsi->attr_gencount ||
!nfs_readdir_inode_mapping_valid(nfsi)) {
desc->duped = 0;
--
2.35.1

2022-03-14 03:43:42

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH v10 07/26] NFS: Store the change attribute in the directory page cache

From: Trond Myklebust <[email protected]>

Use the change attribute and the first cookie in a directory page cache
entry to validate that the page is up to date.

Suggested-by: Benjamin Coddington <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/dir.c | 68 ++++++++++++++++++++++++++++------------------------
1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 6f0a38db6c37..a1767f755460 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -140,6 +140,7 @@ struct nfs_cache_array_entry {
};

struct nfs_cache_array {
+ u64 change_attr;
u64 last_cookie;
unsigned int size;
unsigned char page_full : 1,
@@ -176,12 +177,14 @@ static void nfs_readdir_array_init(struct nfs_cache_array *array)
memset(array, 0, sizeof(struct nfs_cache_array));
}

-static void nfs_readdir_page_init_array(struct page *page, u64 last_cookie)
+static void nfs_readdir_page_init_array(struct page *page, u64 last_cookie,
+ u64 change_attr)
{
struct nfs_cache_array *array;

array = kmap_atomic(page);
nfs_readdir_array_init(array);
+ array->change_attr = change_attr;
array->last_cookie = last_cookie;
array->cookies_are_ordered = 1;
kunmap_atomic(array);
@@ -208,7 +211,7 @@ nfs_readdir_page_array_alloc(u64 last_cookie, gfp_t gfp_flags)
{
struct page *page = alloc_page(gfp_flags);
if (page)
- nfs_readdir_page_init_array(page, last_cookie);
+ nfs_readdir_page_init_array(page, last_cookie, 0);
return page;
}

@@ -305,19 +308,43 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
return ret;
}

+static bool nfs_readdir_page_validate(struct page *page, u64 last_cookie,
+ u64 change_attr)
+{
+ struct nfs_cache_array *array = kmap_atomic(page);
+ int ret = true;
+
+ if (array->change_attr != change_attr)
+ ret = false;
+ if (array->size > 0 && array->array[0].cookie != last_cookie)
+ ret = false;
+ kunmap_atomic(array);
+ return ret;
+}
+
+static void nfs_readdir_page_unlock_and_put(struct page *page)
+{
+ unlock_page(page);
+ put_page(page);
+}
+
static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
pgoff_t index, u64 last_cookie)
{
struct page *page;
+ u64 change_attr;

page = grab_cache_page(mapping, index);
- if (page && !PageUptodate(page)) {
- nfs_readdir_page_init_array(page, last_cookie);
- if (invalidate_inode_pages2_range(mapping, index + 1, -1) < 0)
- nfs_zap_mapping(mapping->host, mapping);
- SetPageUptodate(page);
+ if (!page)
+ return NULL;
+ change_attr = inode_peek_iversion_raw(mapping->host);
+ if (PageUptodate(page)) {
+ if (nfs_readdir_page_validate(page, last_cookie, change_attr))
+ return page;
+ nfs_readdir_clear_array(page);
}
-
+ nfs_readdir_page_init_array(page, last_cookie, change_attr);
+ SetPageUptodate(page);
return page;
}

@@ -357,12 +384,6 @@ static void nfs_readdir_page_set_eof(struct page *page)
kunmap_atomic(array);
}

-static void nfs_readdir_page_unlock_and_put(struct page *page)
-{
- unlock_page(page);
- put_page(page);
-}
-
static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
pgoff_t index, u64 cookie)
{
@@ -419,16 +440,6 @@ static int nfs_readdir_search_for_pos(struct nfs_cache_array *array,
return -EBADCOOKIE;
}

-static bool
-nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
-{
- if (nfsi->cache_validity & (NFS_INO_INVALID_CHANGE |
- NFS_INO_INVALID_DATA))
- return false;
- smp_rmb();
- return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
-}
-
static bool nfs_readdir_array_cookie_in_range(struct nfs_cache_array *array,
u64 cookie)
{
@@ -457,8 +468,7 @@ static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));

new_pos = nfs_readdir_page_offset(desc->page) + i;
- if (desc->attr_gencount != nfsi->attr_gencount ||
- !nfs_readdir_inode_mapping_valid(nfsi)) {
+ if (desc->attr_gencount != nfsi->attr_gencount) {
desc->duped = 0;
desc->attr_gencount = nfsi->attr_gencount;
} else if (new_pos < desc->prev_index) {
@@ -1095,11 +1105,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
* to either find the entry with the appropriate number or
* revalidate the cookie.
*/
- if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) {
- res = nfs_revalidate_mapping(inode, file->f_mapping);
- if (res < 0)
- goto out;
- }
+ nfs_revalidate_mapping(inode, file->f_mapping);

res = -ENOMEM;
desc = kzalloc(sizeof(*desc), GFP_KERNEL);
--
2.35.1