Following this mail is a series of patches to fix an issue with NFS whereby
caching can be enabled on a file that is open for writing by subsequently
opening it for reading. This can be made to crash by opening it for writing
again if you're quick enough.
The patches mailed here may not apply directly. They are based on top of three
fix patches as can be seen in the GIT branch here:
http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache
The gist of the patchset is that the cookie should be acquired at inode
creation only and subsequently enabled and disabled as appropriate (which
dispenses with the backing objects when they're not needed).
The extra synchronisation that NFS does can then be dispensed with as it is
thenceforth managed by FS-Cache.
This likely will need applying to CIFS, Ceph and 9P also once this is okayed
for NFS. AFS is probably safe.
David
---
David Howells (3):
FS-Cache: Add use/unuse/wake cookie wrappers
FS-Cache: Provide the ability to enable/disable cookies
NFS: Use i_writecount to control whether to get an fscache cookie in nfs_open()
Documentation/filesystems/caching/netfs-api.txt | 73 +++++++--
fs/9p/cache.c | 6 -
fs/afs/cell.c | 2
fs/afs/inode.c | 2
fs/afs/vlocation.c | 3
fs/afs/volume.c | 2
fs/cachefiles/interface.c | 2
fs/ceph/cache.c | 4
fs/cifs/fscache.c | 8 -
fs/fscache/cookie.c | 193 +++++++++++++++++------
fs/fscache/fsdef.c | 1
fs/fscache/netfs.c | 1
fs/fscache/object.c | 7 +
fs/fscache/page.c | 59 +++++--
fs/nfs/dir.c | 2
fs/nfs/fscache.c | 196 +++++++----------------
fs/nfs/fscache.h | 18 +-
fs/nfs/inode.c | 6 -
fs/nfs/nfs4file.c | 2
include/linux/fs.h | 5 +
include/linux/fscache-cache.h | 50 ++----
include/linux/fscache.h | 113 ++++++++++++-
include/linux/nfs_fs.h | 8 +
23 files changed, 462 insertions(+), 301 deletions(-)
Add wrapper functions for dealing with cookie->n_active:
(*) __fscache_use_cookie() to increment it.
(*) __fscache_unuse_cookie() to decrement and test against zero.
(*) __fscache_wake_unused_cookie() to wake up anyone waiting for it to reach
zero.
The second and third are split so that the third can be done after cookie->lock
has been released in case the waiter wakes up whilst we're still holding it and
tries to get it.
We will need to wake-on-zero once the cookie disablement patch is applied
because it will then be possible to see n_active become zero without the cookie
being relinquished.
Also move the cookie usement out of fscache_attr_changed_op() and into
fscache_attr_changed() and the operation struct so that cookie disablement
will be able to track it.
Whilst we're at it, only increment n_active if we're about to do
fscache_submit_op() so that we don't have to deal with undoing it if anything
earlier fails. Possibly this should be moved into fscache_submit_op() which
could look at FSCACHE_OP_UNUSE_COOKIE.
Signed-off-by: David Howells <[email protected]>
---
fs/fscache/cookie.c | 7 +++++--
fs/fscache/page.c | 42 ++++++++++++++++++++++++++++++-----------
include/linux/fscache-cache.h | 19 +++++++++++++++++--
3 files changed, 53 insertions(+), 15 deletions(-)
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index b2a86e3..d851aa5 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -568,6 +568,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
{
struct fscache_operation *op;
struct fscache_object *object;
+ bool wake_cookie = false;
int ret;
_enter("%p,", cookie);
@@ -600,7 +601,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
- atomic_inc(&cookie->n_active);
+ __fscache_use_cookie(cookie);
if (fscache_submit_op(object, op) < 0)
goto submit_failed;
@@ -622,9 +623,11 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
return ret;
submit_failed:
- atomic_dec(&cookie->n_active);
+ wake_cookie = __fscache_unuse_cookie(cookie);
inconsistent:
spin_unlock(&cookie->lock);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
kfree(op);
_leave(" = -ESTALE");
return -ESTALE;
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 73899c1..0fe42a6 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -163,12 +163,10 @@ static void fscache_attr_changed_op(struct fscache_operation *op)
fscache_stat(&fscache_n_attr_changed_calls);
- if (fscache_object_is_active(object) &&
- fscache_use_cookie(object)) {
+ if (fscache_object_is_active(object)) {
fscache_stat(&fscache_n_cop_attr_changed);
ret = object->cache->ops->attr_changed(object);
fscache_stat_d(&fscache_n_cop_attr_changed);
- fscache_unuse_cookie(object);
if (ret < 0)
fscache_abort_object(object);
}
@@ -184,6 +182,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
{
struct fscache_operation *op;
struct fscache_object *object;
+ bool wake_cookie;
_enter("%p", cookie);
@@ -199,7 +198,9 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
}
fscache_operation_init(op, fscache_attr_changed_op, NULL);
- op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE);
+ op->flags = FSCACHE_OP_ASYNC |
+ (1 << FSCACHE_OP_EXCLUSIVE) |
+ (1 << FSCACHE_OP_UNUSE_COOKIE);
spin_lock(&cookie->lock);
@@ -208,6 +209,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
+ __fscache_use_cookie(cookie);
if (fscache_submit_exclusive_op(object, op) < 0)
goto nobufs;
spin_unlock(&cookie->lock);
@@ -217,8 +219,11 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
return 0;
nobufs:
+ wake_cookie = __fscache_unuse_cookie(cookie);
spin_unlock(&cookie->lock);
kfree(op);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
fscache_stat(&fscache_n_attr_changed_nobufs);
_leave(" = %d", -ENOBUFS);
return -ENOBUFS;
@@ -263,7 +268,6 @@ static struct fscache_retrieval *fscache_alloc_retrieval(
}
fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
- atomic_inc(&cookie->n_active);
op->op.flags = FSCACHE_OP_MYTHREAD |
(1UL << FSCACHE_OP_WAITING) |
(1UL << FSCACHE_OP_UNUSE_COOKIE);
@@ -384,6 +388,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
{
struct fscache_retrieval *op;
struct fscache_object *object;
+ bool wake_cookie = false;
int ret;
_enter("%p,%p,,,", cookie, page);
@@ -421,6 +426,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags));
+ __fscache_use_cookie(cookie);
atomic_inc(&object->n_reads);
__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
@@ -475,9 +481,11 @@ error:
nobufs_unlock_dec:
atomic_dec(&object->n_reads);
+ wake_cookie = __fscache_unuse_cookie(cookie);
nobufs_unlock:
spin_unlock(&cookie->lock);
- atomic_dec(&cookie->n_active);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
kfree(op);
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
@@ -514,6 +522,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
{
struct fscache_retrieval *op;
struct fscache_object *object;
+ bool wake_cookie = false;
int ret;
_enter("%p,,%d,,,", cookie, *nr_pages);
@@ -547,6 +556,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
+ __fscache_use_cookie(cookie);
atomic_inc(&object->n_reads);
__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
@@ -601,10 +611,12 @@ error:
nobufs_unlock_dec:
atomic_dec(&object->n_reads);
+ wake_cookie = __fscache_unuse_cookie(cookie);
nobufs_unlock:
spin_unlock(&cookie->lock);
- atomic_dec(&cookie->n_active);
kfree(op);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
_leave(" = -ENOBUFS");
@@ -626,6 +638,7 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
{
struct fscache_retrieval *op;
struct fscache_object *object;
+ bool wake_cookie = false;
int ret;
_enter("%p,%p,,,", cookie, page);
@@ -658,8 +671,9 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
+ __fscache_use_cookie(cookie);
if (fscache_submit_op(object, &op->op) < 0)
- goto nobufs_unlock;
+ goto nobufs_unlock_dec;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_alloc_ops);
@@ -689,10 +703,13 @@ error:
_leave(" = %d", ret);
return ret;
+nobufs_unlock_dec:
+ wake_cookie = __fscache_unuse_cookie(cookie);
nobufs_unlock:
spin_unlock(&cookie->lock);
- atomic_dec(&cookie->n_active);
kfree(op);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
nobufs:
fscache_stat(&fscache_n_allocs_nobufs);
_leave(" = -ENOBUFS");
@@ -889,6 +906,7 @@ int __fscache_write_page(struct fscache_cookie *cookie,
{
struct fscache_storage *op;
struct fscache_object *object;
+ bool wake_cookie = false;
int ret;
_enter("%p,%x,", cookie, (u32) page->flags);
@@ -957,7 +975,7 @@ int __fscache_write_page(struct fscache_cookie *cookie,
op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
op->store_limit = object->store_limit;
- atomic_inc(&cookie->n_active);
+ __fscache_use_cookie(cookie);
if (fscache_submit_op(object, &op->op) < 0)
goto submit_failed;
@@ -984,10 +1002,10 @@ already_pending:
return 0;
submit_failed:
- atomic_dec(&cookie->n_active);
spin_lock(&cookie->stores_lock);
radix_tree_delete(&cookie->stores, page->index);
spin_unlock(&cookie->stores_lock);
+ wake_cookie = __fscache_unuse_cookie(cookie);
page_cache_release(page);
ret = -ENOBUFS;
goto nobufs;
@@ -999,6 +1017,8 @@ nobufs:
spin_unlock(&cookie->lock);
radix_tree_preload_end();
kfree(op);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
fscache_stat(&fscache_n_stores_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 7823e9e..96a2b66 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -511,6 +511,11 @@ static inline void fscache_end_io(struct fscache_retrieval *op,
op->end_io_func(page, op->context, error);
}
+static inline void __fscache_use_cookie(struct fscache_cookie *cookie)
+{
+ atomic_inc(&cookie->n_active);
+}
+
/**
* fscache_use_cookie - Request usage of cookie attached to an object
* @object: Object description
@@ -524,6 +529,16 @@ static inline bool fscache_use_cookie(struct fscache_object *object)
return atomic_inc_not_zero(&cookie->n_active) != 0;
}
+static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie)
+{
+ return atomic_dec_and_test(&cookie->n_active);
+}
+
+static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie)
+{
+ wake_up_atomic_t(&cookie->n_active);
+}
+
/**
* fscache_unuse_cookie - Cease usage of cookie attached to an object
* @object: Object description
@@ -534,8 +549,8 @@ static inline bool fscache_use_cookie(struct fscache_object *object)
static inline void fscache_unuse_cookie(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
- if (atomic_dec_and_test(&cookie->n_active))
- wake_up_atomic_t(&cookie->n_active);
+ if (__fscache_unuse_cookie(cookie))
+ __fscache_wake_unused_cookie(cookie);
}
/*
Provide the ability to enable and disable fscache cookies. A disabled cookie
will reject or ignore further requests to:
Acquire a child cookie
Invalidate and update backing objects
Check the consistency of a backing object
Allocate storage for backing page
Read backing pages
Write to backing pages
but still allows:
Checks/waits on the completion of already in-progress objects
Uncaching of pages
Relinquishment of cookies
Two new operations are provided:
(1) Disable a cookie:
void fscache_disable_cookie(struct fscache_cookie *cookie,
bool invalidate);
If the cookie is not already disabled, this locks the cookie against other
dis/enablement ops, marks the cookie as being disabled, discards or
invalidates any backing objects and waits for cessation of activity on any
associated object.
This is a wrapper around a chunk split out of fscache_relinquish_cookie(),
but it reinitialises the cookie such that it can be reenabled.
All possible failures are handled internally. The caller should consider
calling fscache_uncache_all_inode_pages() afterwards to make sure all page
markings are cleared up.
(2) Enable a cookie:
void fscache_enable_cookie(struct fscache_cookie *cookie,
bool (*can_enable)(void *data),
void *data)
If the cookie is not already enabled, this locks the cookie against other
dis/enablement ops, invokes can_enable() and, if the cookie is not an
index cookie, will begin the procedure of acquiring backing objects.
The optional can_enable() function is passed the data argument and returns
a ruling as to whether or not enablement should actually be permitted to
begin.
All possible failures are handled internally. The cookie will only be
marked as enabled if provisional backing objects are allocated.
A later patch will introduce these to NFS. Cookie enablement during nfs_open()
is then contingent on i_writecount <= 0. can_enable() checks for a race
between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie
handling and allows us to get rid of open(O_RDONLY) accidentally introducing
caching to an inode that's open for writing already.
One operation has its API modified:
(3) Acquire a cookie.
struct fscache_cookie *fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
void *netfs_data,
bool enable);
This now has an additional argument that indicates whether the requested
cookie should be enabled by default. It doesn't need the can_enable()
function because the caller must prevent multiple calls for the same netfs
object and it doesn't need to take the enablement lock because no one else
can get at the cookie before this returns.
Signed-off-by: David Howells <[email protected]
---
Documentation/filesystems/caching/netfs-api.txt | 73 +++++++--
fs/9p/cache.c | 6 -
fs/afs/cell.c | 2
fs/afs/inode.c | 2
fs/afs/vlocation.c | 3
fs/afs/volume.c | 2
fs/cachefiles/interface.c | 2
fs/ceph/cache.c | 4
fs/cifs/fscache.c | 8 -
fs/fscache/cookie.c | 186 +++++++++++++++++------
fs/fscache/fsdef.c | 1
fs/fscache/netfs.c | 1
fs/fscache/object.c | 7 +
fs/fscache/page.c | 17 +-
fs/nfs/fscache.c | 8 -
include/linux/fscache-cache.h | 31 ----
include/linux/fscache.h | 113 ++++++++++++--
17 files changed, 334 insertions(+), 132 deletions(-)
diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt
index 11a0a40..aed6b94 100644
--- a/Documentation/filesystems/caching/netfs-api.txt
+++ b/Documentation/filesystems/caching/netfs-api.txt
@@ -29,15 +29,16 @@ This document contains the following sections:
(6) Index registration
(7) Data file registration
(8) Miscellaneous object registration
- (9) Setting the data file size
+ (9) Setting the data file size
(10) Page alloc/read/write
(11) Page uncaching
(12) Index and data file consistency
- (13) Miscellaneous cookie operations
- (14) Cookie unregistration
- (15) Index invalidation
- (16) Data file invalidation
- (17) FS-Cache specific page flags.
+ (13) Cookie enablement
+ (14) Miscellaneous cookie operations
+ (15) Cookie unregistration
+ (16) Index invalidation
+ (17) Data file invalidation
+ (18) FS-Cache specific page flags.
=============================
@@ -334,7 +335,8 @@ the path to the file:
struct fscache_cookie *
fscache_acquire_cookie(struct fscache_cookie *parent,
const struct fscache_object_def *def,
- void *netfs_data);
+ void *netfs_data,
+ bool enable);
This function creates an index entry in the index represented by parent,
filling in the index entry by calling the operations pointed to by def.
@@ -350,6 +352,10 @@ object needs to be created somewhere down the hierarchy. Furthermore, an index
may be created in several different caches independently at different times.
This is all handled transparently, and the netfs doesn't see any of it.
+A cookie will be created in the disabled state if enabled is false. A cookie
+must be enabled to do anything with it. A disabled cookie can be enabled by
+calling fscache_enable_cookie() (see below).
+
For example, with AFS, a cell would be added to the primary index. This index
entry would have a dependent inode containing a volume location index for the
volume mappings within this cell:
@@ -357,7 +363,7 @@ volume mappings within this cell:
cell->cache =
fscache_acquire_cookie(afs_cache_netfs.primary_index,
&afs_cell_cache_index_def,
- cell);
+ cell, true);
Then when a volume location was accessed, it would be entered into the cell's
index and an inode would be allocated that acts as a volume type and hash chain
@@ -366,7 +372,7 @@ combination:
vlocation->cache =
fscache_acquire_cookie(cell->cache,
&afs_vlocation_cache_index_def,
- vlocation);
+ vlocation, true);
And then a particular flavour of volume (R/O for example) could be added to
that index, creating another index for vnodes (AFS inode equivalents):
@@ -374,7 +380,7 @@ that index, creating another index for vnodes (AFS inode equivalents):
volume->cache =
fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
- volume);
+ volume, true);
======================
@@ -388,7 +394,7 @@ the object definition should be something other than index type.
vnode->cache =
fscache_acquire_cookie(volume->cache,
&afs_vnode_cache_object_def,
- vnode);
+ vnode, true);
=================================
@@ -404,7 +410,7 @@ it would be some other type of object such as a data file.
xattr->cache =
fscache_acquire_cookie(vnode->cache,
&afs_xattr_cache_object_def,
- xattr);
+ xattr, true);
Miscellaneous objects might be used to store extended attributes or directory
entries for example.
@@ -733,6 +739,47 @@ Note that partial updates may happen automatically at other times, such as when
data blocks are added to a data file object.
+=================
+COOKIE ENABLEMENT
+=================
+
+Cookies exist in one of two states: enabled and disabled. If a cookie is
+disabled, it ignores all attempts to acquire child cookies; check, update or
+invalidate its state; allocate, read or write backing pages - though it is
+still possible to uncache pages and relinquish the cookie.
+
+The initial enablement state is set by fscache_acquire_cookie(), but the cookie
+can be enabled or disabled later. To disable a cookie, call:
+
+ void fscache_disable_cookie(struct fscache_cookie *cookie,
+ bool invalidate);
+
+If the cookie is not already disabled, this locks the cookie against other
+enable and disable ops, marks the cookie as being disabled, discards or
+invalidates any backing objects and waits for cessation of activity on any
+associated object before unlocking the cookie.
+
+All possible failures are handled internally. The caller should consider
+calling fscache_uncache_all_inode_pages() afterwards to make sure all page
+markings are cleared up.
+
+Cookies can be enabled or reenabled with:
+
+ void fscache_enable_cookie(struct fscache_cookie *cookie,
+ bool (*can_enable)(void *data),
+ void *data)
+
+If the cookie is not already enabled, this locks the cookie against other
+enable and disable ops, invokes can_enable() and, if the cookie is not an index
+cookie, will begin the procedure of acquiring backing objects.
+
+The optional can_enable() function is passed the data argument and returns a
+ruling as to whether or not enablement should actually be permitted to begin.
+
+All possible failures are handled internally. The cookie will only be marked
+as enabled if provisional backing objects are allocated.
+
+
===============================
MISCELLANEOUS COOKIE OPERATIONS
===============================
@@ -778,7 +825,7 @@ COOKIE UNREGISTRATION
To get rid of a cookie, this function should be called.
void fscache_relinquish_cookie(struct fscache_cookie *cookie,
- int retire);
+ bool retire);
If retire is non-zero, then the object will be marked for recycling, and all
copies of it will be removed from all active caches in which it is present.
diff --git a/fs/9p/cache.c b/fs/9p/cache.c
index a9ea73d..2b7a032 100644
--- a/fs/9p/cache.c
+++ b/fs/9p/cache.c
@@ -90,7 +90,7 @@ void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
&v9fs_cache_session_index_def,
- v9ses);
+ v9ses, true);
p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
v9ses, v9ses->fscache);
}
@@ -204,7 +204,7 @@ void v9fs_cache_inode_get_cookie(struct inode *inode)
v9ses = v9fs_inode2v9ses(inode);
v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
&v9fs_cache_inode_index_def,
- v9inode);
+ v9inode, true);
p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
inode, v9inode->fscache);
@@ -271,7 +271,7 @@ void v9fs_cache_inode_reset_cookie(struct inode *inode)
v9ses = v9fs_inode2v9ses(inode);
v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
&v9fs_cache_inode_index_def,
- v9inode);
+ v9inode, true);
p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
inode, old, v9inode->fscache);
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 3c090b7..ca0a3cf 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -179,7 +179,7 @@ struct afs_cell *afs_cell_create(const char *name, unsigned namesz,
/* put it up for caching (this never returns an error) */
cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
&afs_cell_cache_index_def,
- cell);
+ cell, true);
#endif
/* add to the cell lists */
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 789bc25..ce25d75 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -259,7 +259,7 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
#ifdef CONFIG_AFS_FSCACHE
vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
&afs_vnode_cache_index_def,
- vnode);
+ vnode, true);
#endif
ret = afs_inode_map_status(vnode, key);
diff --git a/fs/afs/vlocation.c b/fs/afs/vlocation.c
index 57bcb15..b6df2e8 100644
--- a/fs/afs/vlocation.c
+++ b/fs/afs/vlocation.c
@@ -308,7 +308,8 @@ static int afs_vlocation_fill_in_record(struct afs_vlocation *vl,
/* see if we have an in-cache copy (will set vl->valid if there is) */
#ifdef CONFIG_AFS_FSCACHE
vl->cache = fscache_acquire_cookie(vl->cell->cache,
- &afs_vlocation_cache_index_def, vl);
+ &afs_vlocation_cache_index_def, vl,
+ true);
#endif
if (vl->valid) {
diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 401eeb2..2b60725 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -131,7 +131,7 @@ struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
#ifdef CONFIG_AFS_FSCACHE
volume->cache = fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
- volume);
+ volume, true);
#endif
afs_get_vlocation(vlocation);
volume->vlocation = vlocation;
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 43eb559..00baf14 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -270,7 +270,7 @@ static void cachefiles_drop_object(struct fscache_object *_object)
#endif
/* delete retired objects */
- if (test_bit(FSCACHE_COOKIE_RETIRED, &object->fscache.cookie->flags) &&
+ if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) &&
_object != cache->cache.fsdef
) {
_debug("- retire object OBJ%x", object->fscache.debug_id);
diff --git a/fs/ceph/cache.c b/fs/ceph/cache.c
index 6bfe65e..7db2e6c 100644
--- a/fs/ceph/cache.c
+++ b/fs/ceph/cache.c
@@ -68,7 +68,7 @@ int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
{
fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
&ceph_fscache_fsid_object_def,
- fsc);
+ fsc, true);
if (fsc->fscache == NULL) {
pr_err("Unable to resgister fsid: %p fscache cookie", fsc);
@@ -204,7 +204,7 @@ void ceph_fscache_register_inode_cookie(struct ceph_fs_client* fsc,
ci->fscache = fscache_acquire_cookie(fsc->fscache,
&ceph_fscache_inode_object_def,
- ci);
+ ci, true);
done:
mutex_unlock(&inode->i_mutex);
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index b3258f3..8d4b7bc 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -27,7 +27,7 @@ void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
{
server->fscache =
fscache_acquire_cookie(cifs_fscache_netfs.primary_index,
- &cifs_fscache_server_index_def, server);
+ &cifs_fscache_server_index_def, server, true);
cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
__func__, server, server->fscache);
}
@@ -46,7 +46,7 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
tcon->fscache =
fscache_acquire_cookie(server->fscache,
- &cifs_fscache_super_index_def, tcon);
+ &cifs_fscache_super_index_def, tcon, true);
cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
__func__, server->fscache, tcon->fscache);
}
@@ -69,7 +69,7 @@ static void cifs_fscache_enable_inode_cookie(struct inode *inode)
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_FSCACHE) {
cifsi->fscache = fscache_acquire_cookie(tcon->fscache,
- &cifs_fscache_inode_object_def, cifsi);
+ &cifs_fscache_inode_object_def, cifsi, true);
cifs_dbg(FYI, "%s: got FH cookie (0x%p/0x%p)\n",
__func__, tcon->fscache, cifsi->fscache);
}
@@ -119,7 +119,7 @@ void cifs_fscache_reset_inode_cookie(struct inode *inode)
cifsi->fscache = fscache_acquire_cookie(
cifs_sb_master_tcon(cifs_sb)->fscache,
&cifs_fscache_inode_object_def,
- cifsi);
+ cifsi, true);
cifs_dbg(FYI, "%s: new cookie 0x%p oldcookie 0x%p\n",
__func__, cifsi->fscache, old);
}
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index d851aa5..29d7feb 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -58,15 +58,16 @@ void fscache_cookie_init_once(void *_cookie)
struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
- void *netfs_data)
+ void *netfs_data,
+ bool enable)
{
struct fscache_cookie *cookie;
BUG_ON(!def);
- _enter("{%s},{%s},%p",
+ _enter("{%s},{%s},%p,%u",
parent ? (char *) parent->def->name : "<no-parent>",
- def->name, netfs_data);
+ def->name, netfs_data, enable);
fscache_stat(&fscache_n_acquires);
@@ -106,7 +107,7 @@ struct fscache_cookie *__fscache_acquire_cookie(
cookie->def = def;
cookie->parent = parent;
cookie->netfs_data = netfs_data;
- cookie->flags = 0;
+ cookie->flags = (1 << FSCACHE_COOKIE_NO_DATA_YET);
/* radix tree insertion won't use the preallocation pool unless it's
* told it may not wait */
@@ -124,16 +125,22 @@ struct fscache_cookie *__fscache_acquire_cookie(
break;
}
- /* if the object is an index then we need do nothing more here - we
- * create indices on disk when we need them as an index may exist in
- * multiple caches */
- if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
- if (fscache_acquire_non_index_cookie(cookie) < 0) {
- atomic_dec(&parent->n_children);
- __fscache_cookie_put(cookie);
- fscache_stat(&fscache_n_acquires_nobufs);
- _leave(" = NULL");
- return NULL;
+ if (enable) {
+ /* if the object is an index then we need do nothing more here
+ * - we create indices on disk when we need them as an index
+ * may exist in multiple caches */
+ if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+ if (fscache_acquire_non_index_cookie(cookie) == 0) {
+ set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+ } else {
+ atomic_dec(&parent->n_children);
+ __fscache_cookie_put(cookie);
+ fscache_stat(&fscache_n_acquires_nobufs);
+ _leave(" = NULL");
+ return NULL;
+ }
+ } else {
+ set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
}
}
@@ -144,6 +151,39 @@ struct fscache_cookie *__fscache_acquire_cookie(
EXPORT_SYMBOL(__fscache_acquire_cookie);
/*
+ * Enable a cookie to permit it to accept new operations.
+ */
+void __fscache_enable_cookie(struct fscache_cookie *cookie,
+ bool (*can_enable)(void *data),
+ void *data)
+{
+ _enter("%p", cookie);
+
+ wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
+ fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+
+ if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
+ goto out_unlock;
+
+ if (can_enable && !can_enable(data)) {
+ /* The netfs decided it didn't want to enable after all */
+ } else if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+ /* Wait for outstanding disablement to complete */
+ __fscache_wait_on_invalidate(cookie);
+
+ if (fscache_acquire_non_index_cookie(cookie) == 0)
+ set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+ } else {
+ set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+ }
+
+out_unlock:
+ clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
+ wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
+}
+EXPORT_SYMBOL(__fscache_enable_cookie);
+
+/*
* acquire a non-index cookie
* - this must make sure the index chain is instantiated and instantiate the
* object representation too
@@ -157,7 +197,7 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
_enter("");
- cookie->flags = 1 << FSCACHE_COOKIE_UNAVAILABLE;
+ set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
/* now we need to see whether the backing objects for this cookie yet
* exist, if not there'll be nothing to search */
@@ -180,9 +220,7 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
_debug("cache %s", cache->tag->name);
- cookie->flags =
- (1 << FSCACHE_COOKIE_LOOKING_UP) |
- (1 << FSCACHE_COOKIE_NO_DATA_YET);
+ set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
/* ask the cache to allocate objects for this cookie and its parent
* chain */
@@ -398,7 +436,8 @@ void __fscache_invalidate(struct fscache_cookie *cookie)
if (!hlist_empty(&cookie->backing_objects)) {
spin_lock(&cookie->lock);
- if (!hlist_empty(&cookie->backing_objects) &&
+ if (fscache_cookie_enabled(cookie) &&
+ !hlist_empty(&cookie->backing_objects) &&
!test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
&cookie->flags)) {
object = hlist_entry(cookie->backing_objects.first,
@@ -452,10 +491,14 @@ void __fscache_update_cookie(struct fscache_cookie *cookie)
spin_lock(&cookie->lock);
- /* update the index entry on disk in each cache backing this cookie */
- hlist_for_each_entry(object,
- &cookie->backing_objects, cookie_link) {
- fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
+ if (fscache_cookie_enabled(cookie)) {
+ /* update the index entry on disk in each cache backing this
+ * cookie.
+ */
+ hlist_for_each_entry(object,
+ &cookie->backing_objects, cookie_link) {
+ fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
+ }
}
spin_unlock(&cookie->lock);
@@ -464,28 +507,14 @@ void __fscache_update_cookie(struct fscache_cookie *cookie)
EXPORT_SYMBOL(__fscache_update_cookie);
/*
- * release a cookie back to the cache
- * - the object will be marked as recyclable on disk if retire is true
- * - all dependents of this cookie must have already been unregistered
- * (indices/files/pages)
+ * Disable a cookie to stop it from accepting new requests from the netfs.
*/
-void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
{
struct fscache_object *object;
+ bool awaken = false;
- fscache_stat(&fscache_n_relinquishes);
- if (retire)
- fscache_stat(&fscache_n_relinquishes_retire);
-
- if (!cookie) {
- fscache_stat(&fscache_n_relinquishes_null);
- _leave(" [no cookie]");
- return;
- }
-
- _enter("%p{%s,%p,%d},%d",
- cookie, cookie->def->name, cookie->netfs_data,
- atomic_read(&cookie->n_active), retire);
+ _enter("%p,%u", cookie, invalidate);
ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
@@ -495,24 +524,82 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
BUG();
}
- /* No further netfs-accessing operations on this cookie permitted */
- set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags);
- if (retire)
- set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
+ wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
+ fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+ if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
+ goto out_unlock_enable;
+
+ /* If the cookie is being invalidated, wait for that to complete first
+ * so that we can reuse the flag.
+ */
+ __fscache_wait_on_invalidate(cookie);
+
+ /* Dispose of the backing objects */
+ set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
spin_lock(&cookie->lock);
- hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
- fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
+ if (!hlist_empty(&cookie->backing_objects)) {
+ hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
+ if (invalidate)
+ set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
+ fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
+ }
+ } else {
+ if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
+ awaken = true;
}
spin_unlock(&cookie->lock);
+ if (awaken)
+ wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
/* Wait for cessation of activity requiring access to the netfs (when
- * n_active reaches 0).
+ * n_active reaches 0). This makes sure outstanding reads and writes
+ * have completed.
*/
if (!atomic_dec_and_test(&cookie->n_active))
wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
TASK_UNINTERRUPTIBLE);
+ /* Reset the cookie state if it wasn't relinquished */
+ if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
+ atomic_inc(&cookie->n_active);
+ set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+ }
+
+out_unlock_enable:
+ clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
+ wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
+ _leave("");
+}
+EXPORT_SYMBOL(__fscache_disable_cookie);
+
+/*
+ * release a cookie back to the cache
+ * - the object will be marked as recyclable on disk if retire is true
+ * - all dependents of this cookie must have already been unregistered
+ * (indices/files/pages)
+ */
+void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
+{
+ fscache_stat(&fscache_n_relinquishes);
+ if (retire)
+ fscache_stat(&fscache_n_relinquishes_retire);
+
+ if (!cookie) {
+ fscache_stat(&fscache_n_relinquishes_null);
+ _leave(" [no cookie]");
+ return;
+ }
+
+ _enter("%p{%s,%p,%d},%d",
+ cookie, cookie->def->name, cookie->netfs_data,
+ atomic_read(&cookie->n_active), retire);
+
+ /* No further netfs-accessing operations on this cookie permitted */
+ set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags);
+
+ __fscache_disable_cookie(cookie, retire);
+
/* Clear pointers back to the netfs */
cookie->netfs_data = NULL;
cookie->def = NULL;
@@ -592,7 +679,8 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto inconsistent;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c
index 10a2ade..5a117df 100644
--- a/fs/fscache/fsdef.c
+++ b/fs/fscache/fsdef.c
@@ -59,6 +59,7 @@ struct fscache_cookie fscache_fsdef_index = {
.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
.backing_objects = HLIST_HEAD_INIT,
.def = &fscache_fsdef_index_def,
+ .flags = 1 << FSCACHE_COOKIE_ENABLED,
};
EXPORT_SYMBOL(fscache_fsdef_index);
diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index b1bb611..989f394 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -45,6 +45,7 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
netfs->primary_index->def = &fscache_fsdef_netfs_def;
netfs->primary_index->parent = &fscache_fsdef_index;
netfs->primary_index->netfs_data = netfs;
+ netfs->primary_index->flags = 1 << FSCACHE_COOKIE_ENABLED;
atomic_inc(&netfs->primary_index->parent->usage);
atomic_inc(&netfs->primary_index->parent->n_children);
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 86d75a6..dcb8216 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -495,6 +495,7 @@ void fscache_object_lookup_negative(struct fscache_object *object)
* returning ENODATA.
*/
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+ clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
_debug("wake up lookup %p", &cookie->flags);
clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
@@ -527,6 +528,7 @@ void fscache_obtained_object(struct fscache_object *object)
/* We do (presumably) have data */
clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+ clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
/* Allow write requests to begin stacking up and read requests
* to begin shovelling data.
@@ -679,7 +681,8 @@ static const struct fscache_state *fscache_drop_object(struct fscache_object *ob
*/
spin_lock(&cookie->lock);
hlist_del_init(&object->cookie_link);
- if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
+ if (hlist_empty(&cookie->backing_objects) &&
+ test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
awaken = true;
spin_unlock(&cookie->lock);
@@ -927,7 +930,7 @@ static const struct fscache_state *_fscache_invalidate_object(struct fscache_obj
*/
if (!fscache_use_cookie(object)) {
ASSERT(object->cookie->stores.rnode == NULL);
- set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
+ set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
_leave(" [no cookie]");
return transit_to(KILL_OBJECT);
}
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 0fe42a6..7f5c658 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -204,7 +204,8 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
@@ -410,7 +411,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
return -ERESTARTSYS;
op = fscache_alloc_retrieval(cookie, page->mapping,
- end_io_func,context);
+ end_io_func, context);
if (!op) {
_leave(" = -ENOMEM");
return -ENOMEM;
@@ -419,7 +420,8 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
@@ -551,7 +553,8 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
@@ -666,7 +669,8 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
@@ -938,7 +942,8 @@ int __fscache_write_page(struct fscache_cookie *cookie,
ret = -ENOBUFS;
spin_lock(&cookie->lock);
- if (hlist_empty(&cookie->backing_objects))
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index 24d1d1c..cd6e7ef 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -39,7 +39,7 @@ void nfs_fscache_get_client_cookie(struct nfs_client *clp)
/* create a cache index for looking up filehandles */
clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
&nfs_fscache_server_index_def,
- clp);
+ clp, true);
dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
clp, clp->fscache);
}
@@ -139,7 +139,7 @@ void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int
/* create a cache index for looking up filehandles */
nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
&nfs_fscache_super_index_def,
- nfss);
+ nfss, true);
dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
return;
@@ -200,7 +200,7 @@ static void nfs_fscache_enable_inode_cookie(struct inode *inode)
nfsi->fscache = fscache_acquire_cookie(
NFS_SB(sb)->fscache,
&nfs_fscache_inode_object_def,
- nfsi);
+ nfsi, true);
dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
sb, nfsi, nfsi->fscache);
@@ -327,7 +327,7 @@ void nfs_fscache_reset_inode_cookie(struct inode *inode)
nfsi->fscache = fscache_acquire_cookie(
nfss->nfs_client->fscache,
&nfs_fscache_inode_object_def,
- nfsi);
+ nfsi, true);
dfprintk(FSCACHE,
"NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 96a2b66..7714849 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -308,36 +308,6 @@ struct fscache_cache_ops {
void (*dissociate_pages)(struct fscache_cache *cache);
};
-/*
- * data file or index object cookie
- * - a file will only appear in one cache
- * - a request to cache a file may or may not be honoured, subject to
- * constraints such as disk space
- * - indices are created on disk just-in-time
- */
-struct fscache_cookie {
- atomic_t usage; /* number of users of this cookie */
- atomic_t n_children; /* number of children of this cookie */
- atomic_t n_active; /* number of active users of netfs ptrs */
- spinlock_t lock;
- spinlock_t stores_lock; /* lock on page store tree */
- struct hlist_head backing_objects; /* object(s) backing this file/index */
- const struct fscache_cookie_def *def; /* definition */
- struct fscache_cookie *parent; /* parent of this entry */
- void *netfs_data; /* back pointer to netfs */
- struct radix_tree_root stores; /* pages to be stored on this cookie */
-#define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
-#define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */
-
- unsigned long flags;
-#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
-#define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
-#define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
-#define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
-#define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
-#define FSCACHE_COOKIE_RETIRED 5 /* T if cookie was retired */
-};
-
extern struct fscache_cookie fscache_fsdef_index;
/*
@@ -400,6 +370,7 @@ struct fscache_object {
#define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */
#define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */
#define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */
+#define FSCACHE_OBJECT_RETIRED 6 /* T if object was retired on relinquishment */
struct list_head cache_link; /* link in cache->object_list */
struct hlist_node cookie_link; /* link in cookie->backing_objects */
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 19b4645..115bb81 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -167,6 +167,42 @@ struct fscache_netfs {
};
/*
+ * data file or index object cookie
+ * - a file will only appear in one cache
+ * - a request to cache a file may or may not be honoured, subject to
+ * constraints such as disk space
+ * - indices are created on disk just-in-time
+ */
+struct fscache_cookie {
+ atomic_t usage; /* number of users of this cookie */
+ atomic_t n_children; /* number of children of this cookie */
+ atomic_t n_active; /* number of active users of netfs ptrs */
+ spinlock_t lock;
+ spinlock_t stores_lock; /* lock on page store tree */
+ struct hlist_head backing_objects; /* object(s) backing this file/index */
+ const struct fscache_cookie_def *def; /* definition */
+ struct fscache_cookie *parent; /* parent of this entry */
+ void *netfs_data; /* back pointer to netfs */
+ struct radix_tree_root stores; /* pages to be stored on this cookie */
+#define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
+#define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */
+
+ unsigned long flags;
+#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
+#define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
+#define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
+#define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
+#define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
+#define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */
+#define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */
+};
+
+static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie)
+{
+ return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+}
+
+/*
* slow-path functions for when there is actually caching available, and the
* netfs does actually have a valid token
* - these are not to be called directly
@@ -181,8 +217,8 @@ extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
extern struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *,
const struct fscache_cookie_def *,
- void *);
-extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
+ void *, bool);
+extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
extern int __fscache_check_consistency(struct fscache_cookie *);
extern void __fscache_update_cookie(struct fscache_cookie *);
extern int __fscache_attr_changed(struct fscache_cookie *);
@@ -211,6 +247,9 @@ extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
struct inode *);
extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
struct list_head *pages);
+extern void __fscache_disable_cookie(struct fscache_cookie *, bool);
+extern void __fscache_enable_cookie(struct fscache_cookie *,
+ bool (*)(void *), void *);
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
@@ -289,6 +328,7 @@ void fscache_release_cache_tag(struct fscache_cache_tag *tag)
* @def: A description of the cache object, including callback operations
* @netfs_data: An arbitrary piece of data to be kept in the cookie to
* represent the cache object to the netfs
+ * @enable: Whether or not to enable a data cookie immediately
*
* This function is used to inform FS-Cache about part of an index hierarchy
* that can be used to locate files. This is done by requesting a cookie for
@@ -301,10 +341,12 @@ static inline
struct fscache_cookie *fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
- void *netfs_data)
+ void *netfs_data,
+ bool enable)
{
- if (fscache_cookie_valid(parent))
- return __fscache_acquire_cookie(parent, def, netfs_data);
+ if (fscache_cookie_valid(parent) && fscache_cookie_enabled(parent))
+ return __fscache_acquire_cookie(parent, def, netfs_data,
+ enable);
else
return NULL;
}
@@ -322,7 +364,7 @@ struct fscache_cookie *fscache_acquire_cookie(
* description.
*/
static inline
-void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+void fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
{
if (fscache_cookie_valid(cookie))
__fscache_relinquish_cookie(cookie, retire);
@@ -341,7 +383,7 @@ void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
static inline
int fscache_check_consistency(struct fscache_cookie *cookie)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_check_consistency(cookie);
else
return 0;
@@ -360,7 +402,7 @@ int fscache_check_consistency(struct fscache_cookie *cookie)
static inline
void fscache_update_cookie(struct fscache_cookie *cookie)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
__fscache_update_cookie(cookie);
}
@@ -407,7 +449,7 @@ void fscache_unpin_cookie(struct fscache_cookie *cookie)
static inline
int fscache_attr_changed(struct fscache_cookie *cookie)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_attr_changed(cookie);
else
return -ENOBUFS;
@@ -429,7 +471,7 @@ int fscache_attr_changed(struct fscache_cookie *cookie)
static inline
void fscache_invalidate(struct fscache_cookie *cookie)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
__fscache_invalidate(cookie);
}
@@ -503,7 +545,7 @@ int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
void *context,
gfp_t gfp)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_read_or_alloc_page(cookie, page, end_io_func,
context, gfp);
else
@@ -554,7 +596,7 @@ int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
void *context,
gfp_t gfp)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_read_or_alloc_pages(cookie, mapping, pages,
nr_pages, end_io_func,
context, gfp);
@@ -585,7 +627,7 @@ int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_alloc_page(cookie, page, gfp);
else
return -ENOBUFS;
@@ -634,7 +676,7 @@ int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
- if (fscache_cookie_valid(cookie))
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_write_page(cookie, page, gfp);
else
return -ENOBUFS;
@@ -744,4 +786,47 @@ void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
__fscache_uncache_all_inode_pages(cookie, inode);
}
+/**
+ * fscache_disable_cookie - Disable a cookie
+ * @cookie: The cookie representing the cache object
+ * @invalidate: Invalidate the backing object
+ *
+ * Disable a cookie from accepting further alloc, read, write, invalidate,
+ * update or acquire operations. Outstanding operations can still be waited
+ * upon and pages can still be uncached and the cookie relinquished.
+ *
+ * This will not return until all outstanding operations have completed.
+ *
+ * If @invalidate is set, then the backing object will be invalidated and
+ * detached, otherwise it will just be detached.
+ */
+static inline
+void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
+{
+ if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
+ __fscache_disable_cookie(cookie, invalidate);
+}
+
+/**
+ * fscache_enable_cookie - Reenable a cookie
+ * @cookie: The cookie representing the cache object
+ * @can_enable: A function to permit enablement once lock is held
+ * @data: Data for can_enable()
+ *
+ * Reenable a previously disabled cookie, allowing it to accept further alloc,
+ * read, write, invalidate, update or acquire operations. An attempt will be
+ * made to immediately reattach the cookie to a backing object.
+ *
+ * The can_enable() function is called (if not NULL) once the enablement lock
+ * is held to rule on whether enablement is still permitted to go ahead.
+ */
+static inline
+void fscache_enable_cookie(struct fscache_cookie *cookie,
+ bool (*can_enable)(void *data),
+ void *data)
+{
+ if (fscache_cookie_valid(cookie) && !fscache_cookie_enabled(cookie))
+ __fscache_enable_cookie(cookie, can_enable, data);
+}
+
#endif /* _LINUX_FSCACHE_H */
Use i_writecount to control whether to get an fscache cookie in nfs_open() as
NFS does not do write caching yet. I *think* this is the cause of a problem
encountered by Mark Moseley whereby __fscache_uncache_page() gets a NULL
pointer dereference because cookie->def is NULL:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: [<ffffffff812a1903>] __fscache_uncache_page+0x23/0x160
PGD 0
Thread overran stack, or stack corrupted
Oops: 0000 [#1] SMP
Modules linked in: ...
CPU: 7 PID: 18993 Comm: php Not tainted 3.11.1 #1
Hardware name: Dell Inc. PowerEdge R420/072XWF, BIOS 1.3.5 08/21/2012
task: ffff8804203460c0 ti: ffff880420346640
RIP: 0010:[<ffffffff812a1903>] __fscache_uncache_page+0x23/0x160
RSP: 0018:ffff8801053af878 EFLAGS: 00210286
RAX: 0000000000000000 RBX: ffff8800be2f8780 RCX: ffff88022ffae5e8
RDX: 0000000000004c66 RSI: ffffea00055ff440 RDI: ffff8800be2f8780
RBP: ffff8801053af898 R08: 0000000000000001 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00055ff440
R13: 0000000000001000 R14: ffff8800c50be538 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88042fc60000(0063) knlGS:00000000e439c700
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000010 CR3: 0000000001d8f000 CR4: 00000000000607f0
Stack:
...
Call Trace:
[<ffffffff81365a72>] __nfs_fscache_invalidate_page+0x42/0x70
[<ffffffff813553d5>] nfs_invalidate_page+0x75/0x90
[<ffffffff811b8f5e>] truncate_inode_page+0x8e/0x90
[<ffffffff811b90ad>] truncate_inode_pages_range.part.12+0x14d/0x620
[<ffffffff81d6387d>] ? __mutex_lock_slowpath+0x1fd/0x2e0
[<ffffffff811b95d3>] truncate_inode_pages_range+0x53/0x70
[<ffffffff811b969d>] truncate_inode_pages+0x2d/0x40
[<ffffffff811b96ff>] truncate_pagecache+0x4f/0x70
[<ffffffff81356840>] nfs_setattr_update_inode+0xa0/0x120
[<ffffffff81368de4>] nfs3_proc_setattr+0xc4/0xe0
[<ffffffff81357f78>] nfs_setattr+0xc8/0x150
[<ffffffff8122d95b>] notify_change+0x1cb/0x390
[<ffffffff8120a55b>] do_truncate+0x7b/0xc0
[<ffffffff8121f96c>] do_last+0xa4c/0xfd0
[<ffffffff8121ffbc>] path_openat+0xcc/0x670
[<ffffffff81220a0e>] do_filp_open+0x4e/0xb0
[<ffffffff8120ba1f>] do_sys_open+0x13f/0x2b0
[<ffffffff8126aaf6>] compat_SyS_open+0x36/0x50
[<ffffffff81d7204c>] sysenter_dispatch+0x7/0x24
The code at the instruction pointer was disassembled:
> (gdb) disas __fscache_uncache_page
> Dump of assembler code for function __fscache_uncache_page:
> ...
> 0xffffffff812a18ff <+31>: mov 0x48(%rbx),%rax
> 0xffffffff812a1903 <+35>: cmpb $0x0,0x10(%rax)
> 0xffffffff812a1907 <+39>: je 0xffffffff812a19cd <__fscache_uncache_page+237>
These instructions make up:
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
That cmpb is the faulting instruction (%rax is 0). So cookie->def is NULL -
which presumably means that the cookie has already been at least partway
through __fscache_relinquish_cookie().
What I think may be happening is something like a three-way race on the same
file:
PROCESS 1 PROCESS 2 PROCESS 3
=============== =============== ===============
open(O_TRUNC|O_WRONLY)
open(O_RDONLY)
open(O_WRONLY)
-->nfs_open()
-->nfs_fscache_set_inode_cookie()
nfs_fscache_inode_lock()
nfs_fscache_disable_inode_cookie()
__fscache_relinquish_cookie()
nfs_inode->fscache = NULL
<--nfs_fscache_set_inode_cookie()
-->nfs_open()
-->nfs_fscache_set_inode_cookie()
nfs_fscache_inode_lock()
nfs_fscache_enable_inode_cookie()
__fscache_acquire_cookie()
nfs_inode->fscache = cookie
<--nfs_fscache_set_inode_cookie()
<--nfs_open()
-->nfs_setattr()
...
...
-->nfs_invalidate_page()
-->__nfs_fscache_invalidate_page()
cookie = nfsi->fscache
-->nfs_open()
-->nfs_fscache_set_inode_cookie()
nfs_fscache_inode_lock()
nfs_fscache_disable_inode_cookie()
-->__fscache_relinquish_cookie()
-->__fscache_uncache_page(cookie)
<crash>
<--__fscache_relinquish_cookie()
nfs_inode->fscache = NULL
<--nfs_fscache_set_inode_cookie()
What is needed is something to prevent process #2 from reacquiring the cookie
- and I think checking i_writecount should do the trick.
It's also possible to have a two-way race on this if the file is opened
O_TRUNC|O_RDONLY instead.
Reported-by: Mark Moseley <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/nfs/dir.c | 2 -
fs/nfs/fscache.c | 192 ++++++++++++++----------------------------------
fs/nfs/fscache.h | 18 ++---
fs/nfs/inode.c | 6 +-
fs/nfs/nfs4file.c | 2 -
include/linux/fs.h | 5 +
include/linux/nfs_fs.h | 8 ++
7 files changed, 77 insertions(+), 156 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 854a8f0..4c5edcc 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1381,7 +1381,7 @@ static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, i
static int do_open(struct inode *inode, struct file *filp)
{
- nfs_fscache_set_inode_cookie(inode, filp);
+ nfs_fscache_open_file(inode, filp);
return 0;
}
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index cd6e7ef..a01af20 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -178,163 +178,79 @@ void nfs_fscache_release_super_cookie(struct super_block *sb)
/*
* Initialise the per-inode cache cookie pointer for an NFS inode.
*/
-void nfs_fscache_init_inode_cookie(struct inode *inode)
+void nfs_fscache_init_inode(struct inode *inode)
{
- NFS_I(inode)->fscache = NULL;
- if (S_ISREG(inode->i_mode))
- set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
-}
-
-/*
- * Get the per-inode cache cookie for an NFS inode.
- */
-static void nfs_fscache_enable_inode_cookie(struct inode *inode)
-{
- struct super_block *sb = inode->i_sb;
struct nfs_inode *nfsi = NFS_I(inode);
- if (nfsi->fscache || !NFS_FSCACHE(inode))
+ nfsi->fscache = NULL;
+ if (!S_ISREG(inode->i_mode))
return;
-
- if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
- nfsi->fscache = fscache_acquire_cookie(
- NFS_SB(sb)->fscache,
- &nfs_fscache_inode_object_def,
- nfsi, true);
-
- dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
- sb, nfsi, nfsi->fscache);
- }
+ nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
+ &nfs_fscache_inode_object_def,
+ nfsi, false);
}
/*
* Release a per-inode cookie.
*/
-void nfs_fscache_release_inode_cookie(struct inode *inode)
-{
- struct nfs_inode *nfsi = NFS_I(inode);
-
- dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
- nfsi, nfsi->fscache);
-
- fscache_relinquish_cookie(nfsi->fscache, 0);
- nfsi->fscache = NULL;
-}
-
-/*
- * Retire a per-inode cookie, destroying the data attached to it.
- */
-void nfs_fscache_zap_inode_cookie(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);
- dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
- nfsi, nfsi->fscache);
+ dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
- fscache_relinquish_cookie(nfsi->fscache, 1);
+ fscache_relinquish_cookie(cookie, false);
nfsi->fscache = NULL;
}
-/*
- * Turn off the cache with regard to a per-inode cookie if opened for writing,
- * invalidating all the pages in the page cache relating to the associated
- * inode to clear the per-page caching.
- */
-static void nfs_fscache_disable_inode_cookie(struct inode *inode)
-{
- clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
-
- if (NFS_I(inode)->fscache) {
- dfprintk(FSCACHE,
- "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
-
- /* Need to uncache any pages attached to this inode that
- * fscache knows about before turning off the cache.
- */
- fscache_uncache_all_inode_pages(NFS_I(inode)->fscache, inode);
- nfs_fscache_zap_inode_cookie(inode);
- }
-}
-
-/*
- * wait_on_bit() sleep function for uninterruptible waiting
- */
-static int nfs_fscache_wait_bit(void *flags)
-{
- schedule();
- return 0;
-}
-
-/*
- * Lock against someone else trying to also acquire or relinquish a cookie
- */
-static inline void nfs_fscache_inode_lock(struct inode *inode)
-{
- struct nfs_inode *nfsi = NFS_I(inode);
-
- while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
- wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
- nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
-}
-
-/*
- * Unlock cookie management lock
- */
-static inline void nfs_fscache_inode_unlock(struct inode *inode)
+static bool nfs_fscache_can_enable(void *data)
{
- struct nfs_inode *nfsi = NFS_I(inode);
+ struct inode *inode = data;
- smp_mb__before_clear_bit();
- clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
- smp_mb__after_clear_bit();
- wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
+ return !inode_is_open_for_write(inode);
}
/*
- * Decide if we should enable or disable local caching for this inode.
- * - For now, with NFS, only regular files that are open read-only will be able
- * to use the cache.
- * - May be invoked multiple times in parallel by parallel nfs_open() functions.
- */
-void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
-{
- if (NFS_FSCACHE(inode)) {
- nfs_fscache_inode_lock(inode);
- if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
- nfs_fscache_disable_inode_cookie(inode);
- else
- nfs_fscache_enable_inode_cookie(inode);
- nfs_fscache_inode_unlock(inode);
- }
-}
-EXPORT_SYMBOL_GPL(nfs_fscache_set_inode_cookie);
-
-/*
- * Replace a per-inode cookie due to revalidation detecting a file having
- * changed on the server.
+ * Enable or disable caching for a file that is being opened as appropriate.
+ * The cookie is allocated when the inode is initialised, but is not enabled at
+ * that time. Enablement is deferred to file-open time to avoid stat() and
+ * access() thrashing the cache.
+ *
+ * For now, with NFS, only regular files that are open read-only will be able
+ * to use the cache.
+ *
+ * We enable the cache for an inode if we open it read-only and it isn't
+ * currently open for writing. We disable the cache if the inode is open
+ * write-only.
+ *
+ * The caller uses the file struct to pin i_writecount on the inode before
+ * calling us when a file is opened for writing, so we can make use of that.
+ *
+ * Note that this may be invoked multiple times in parallel by parallel
+ * nfs_open() functions.
*/
-void nfs_fscache_reset_inode_cookie(struct inode *inode)
+void nfs_fscache_open_file(struct inode *inode, struct file *filp)
{
struct nfs_inode *nfsi = NFS_I(inode);
- struct nfs_server *nfss = NFS_SERVER(inode);
- NFS_IFDEBUG(struct fscache_cookie *old = nfsi->fscache);
-
- nfs_fscache_inode_lock(inode);
- if (nfsi->fscache) {
- /* retire the current fscache cache and get a new one */
- fscache_relinquish_cookie(nfsi->fscache, 1);
+ struct fscache_cookie *cookie = nfs_i_fscache(inode);
- nfsi->fscache = fscache_acquire_cookie(
- nfss->nfs_client->fscache,
- &nfs_fscache_inode_object_def,
- nfsi, true);
+ if (!fscache_cookie_valid(cookie))
+ return;
- dfprintk(FSCACHE,
- "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
- nfss, nfsi, old, nfsi->fscache);
+ if (inode_is_open_for_write(inode)) {
+ dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
+ clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
+ fscache_disable_cookie(cookie, true);
+ fscache_uncache_all_inode_pages(cookie, inode);
+ } else {
+ dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
+ fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode);
+ if (fscache_cookie_enabled(cookie))
+ set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
}
- nfs_fscache_inode_unlock(inode);
}
+EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
/*
* Release the caching state associated with a page, if the page isn't busy
@@ -345,7 +261,7 @@ int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
if (PageFsCache(page)) {
struct nfs_inode *nfsi = NFS_I(page->mapping->host);
- struct fscache_cookie *cookie = nfsi->fscache;
+ struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
BUG_ON(!cookie);
dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
@@ -368,7 +284,7 @@ int nfs_fscache_release_page(struct page *page, gfp_t gfp)
void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
- struct fscache_cookie *cookie = nfsi->fscache;
+ struct fscache_cookie *cookie = nfs_i_fscache(inode);
BUG_ON(!cookie);
@@ -417,9 +333,9 @@ int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
dfprintk(FSCACHE,
"NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
- NFS_I(inode)->fscache, page, page->index, page->flags, inode);
+ nfs_i_fscache(inode), page, page->index, page->flags, inode);
- ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
+ ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
page,
nfs_readpage_from_fscache_complete,
ctx,
@@ -459,9 +375,9 @@ int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
int ret;
dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
- NFS_I(inode)->fscache, npages, inode);
+ nfs_i_fscache(inode), npages, inode);
- ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
+ ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
mapping, pages, nr_pages,
nfs_readpage_from_fscache_complete,
ctx,
@@ -506,15 +422,15 @@ void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
dfprintk(FSCACHE,
"NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
- NFS_I(inode)->fscache, page, page->index, page->flags, sync);
+ nfs_i_fscache(inode), page, page->index, page->flags, sync);
- ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
+ ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL);
dfprintk(FSCACHE,
"NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
page, page->index, page->flags, ret);
if (ret != 0) {
- fscache_uncache_page(NFS_I(inode)->fscache, page);
+ fscache_uncache_page(nfs_i_fscache(inode), page);
nfs_add_fscache_stats(inode,
NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 4ecb766..d7fe3e7 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -76,11 +76,9 @@ extern void nfs_fscache_release_client_cookie(struct nfs_client *);
extern void nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
extern void nfs_fscache_release_super_cookie(struct super_block *);
-extern void nfs_fscache_init_inode_cookie(struct inode *);
-extern void nfs_fscache_release_inode_cookie(struct inode *);
-extern void nfs_fscache_zap_inode_cookie(struct inode *);
-extern void nfs_fscache_set_inode_cookie(struct inode *, struct file *);
-extern void nfs_fscache_reset_inode_cookie(struct inode *);
+extern void nfs_fscache_init_inode(struct inode *);
+extern void nfs_fscache_clear_inode(struct inode *);
+extern void nfs_fscache_open_file(struct inode *, struct file *);
extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
extern int nfs_fscache_release_page(struct page *, gfp_t);
@@ -187,12 +185,10 @@ static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
-static inline void nfs_fscache_init_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_release_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_zap_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_set_inode_cookie(struct inode *inode,
- struct file *filp) {}
-static inline void nfs_fscache_reset_inode_cookie(struct inode *inode) {}
+static inline void nfs_fscache_init_inode(struct inode *inode) {}
+static inline void nfs_fscache_clear_inode(struct inode *inode) {}
+static inline void nfs_fscache_open_file(struct inode *inode,
+ struct file *filp) {}
static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index eda8879..bb90bff 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -122,7 +122,7 @@ void nfs_clear_inode(struct inode *inode)
WARN_ON_ONCE(!list_empty(&NFS_I(inode)->open_files));
nfs_zap_acl_cache(inode);
nfs_access_zap_cache(inode);
- nfs_fscache_release_inode_cookie(inode);
+ nfs_fscache_clear_inode(inode);
}
EXPORT_SYMBOL_GPL(nfs_clear_inode);
@@ -459,7 +459,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr, st
nfsi->attrtimeo_timestamp = now;
nfsi->access_cache = RB_ROOT;
- nfs_fscache_init_inode_cookie(inode);
+ nfs_fscache_init_inode(inode);
unlock_new_inode(inode);
} else
@@ -854,7 +854,7 @@ int nfs_open(struct inode *inode, struct file *filp)
return PTR_ERR(ctx);
nfs_file_set_open_context(filp, ctx);
put_nfs_open_context(ctx);
- nfs_fscache_set_inode_cookie(inode, filp);
+ nfs_fscache_open_file(inode, filp);
return 0;
}
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index e5b804d..5b8a618 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -74,7 +74,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
nfs_file_set_open_context(filp, ctx);
- nfs_fscache_set_inode_cookie(inode, filp);
+ nfs_fscache_open_file(inode, filp);
err = 0;
out_put_ctx:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3f40547..955dff5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2292,6 +2292,11 @@ static inline void allow_write_access(struct file *file)
if (file)
atomic_inc(&file_inode(file)->i_writecount);
}
+static inline bool inode_is_open_for_write(const struct inode *inode)
+{
+ return atomic_read(&inode->i_writecount) > 0;
+}
+
#ifdef CONFIG_IMA
static inline void i_readcount_dec(struct inode *inode)
{
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 3ea4cde..14a4820 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -269,9 +269,13 @@ static inline int NFS_STALE(const struct inode *inode)
return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
}
-static inline int NFS_FSCACHE(const struct inode *inode)
+static inline struct fscache_cookie *nfs_i_fscache(struct inode *inode)
{
- return test_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+#ifdef CONFIG_NFS_FSCACHE
+ return NFS_I(inode)->fscache;
+#else
+ return NULL;
+#endif
}
static inline __u64 NFS_FILEID(const struct inode *inode)
This should not be a problem with Ceph as the MDS (the metadata
server) hands out cache capability bit for an inode. In this schema
there's no need to worry about the count of of local file pointers
open for write (or even across the cluster).
As an aside, the Ceph code checks if we can perform the requested VMA
operation by checking the valid_fscache generation (compared to the
current cache generation). This way we only create the cookie the
first time the file is open. This has greatly simplified the code and
got rid of a lot of races.
Best,
- Milosz
On Fri, Sep 20, 2013 at 11:09 AM, David Howells <[email protected]> wrote:
>
>
> Following this mail is a series of patches to fix an issue with NFS whereby
> caching can be enabled on a file that is open for writing by subsequently
> opening it for reading. This can be made to crash by opening it for writing
> again if you're quick enough.
>
> The patches mailed here may not apply directly. They are based on top of three
> fix patches as can be seen in the GIT branch here:
>
> http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache
>
>
> The gist of the patchset is that the cookie should be acquired at inode
> creation only and subsequently enabled and disabled as appropriate (which
> dispenses with the backing objects when they're not needed).
>
> The extra synchronisation that NFS does can then be dispensed with as it is
> thenceforth managed by FS-Cache.
>
> This likely will need applying to CIFS, Ceph and 9P also once this is okayed
> for NFS. AFS is probably safe.
>
> David
> ---
> David Howells (3):
> FS-Cache: Add use/unuse/wake cookie wrappers
> FS-Cache: Provide the ability to enable/disable cookies
> NFS: Use i_writecount to control whether to get an fscache cookie in nfs_open()
>
>
> Documentation/filesystems/caching/netfs-api.txt | 73 +++++++--
> fs/9p/cache.c | 6 -
> fs/afs/cell.c | 2
> fs/afs/inode.c | 2
> fs/afs/vlocation.c | 3
> fs/afs/volume.c | 2
> fs/cachefiles/interface.c | 2
> fs/ceph/cache.c | 4
> fs/cifs/fscache.c | 8 -
> fs/fscache/cookie.c | 193 +++++++++++++++++------
> fs/fscache/fsdef.c | 1
> fs/fscache/netfs.c | 1
> fs/fscache/object.c | 7 +
> fs/fscache/page.c | 59 +++++--
> fs/nfs/dir.c | 2
> fs/nfs/fscache.c | 196 +++++++----------------
> fs/nfs/fscache.h | 18 +-
> fs/nfs/inode.c | 6 -
> fs/nfs/nfs4file.c | 2
> include/linux/fs.h | 5 +
> include/linux/fscache-cache.h | 50 ++----
> include/linux/fscache.h | 113 ++++++++++++-
> include/linux/nfs_fs.h | 8 +
> 23 files changed, 462 insertions(+), 301 deletions(-)
>
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Due to commit 996a2493ed5d3a8d5db03b560fcbbf1ca3f10897 (NFS:
Use i_writecount to control whether to get an fscache cookie in
nfs_open(), in two instances a local variable is only used in debug
print statements. Said statements might be compiled out, which results
in unused variable warnings:
fs/nfs/fscache.c: In function 'nfs_fscache_release_page':
fs/nfs/fscache.c:263:21: warning: unused variable 'nfsi' [-Wunused-variable]
fs/nfs/fscache.c: In function '__nfs_fscache_invalidate_page':
fs/nfs/fscache.c:286:20: warning: unused variable 'nfsi' [-Wunused-variable]
Just skip the local variable in these cases.
Signed-off-by: Olof Johansson <[email protected]>
---
David,
This showed up in today's linux-next, seems to have come in through the fscache tree.
Either amend and roll in the fix (after review -- I'm guessing this is the right thing to do), or apply on top please. :)
Thanks!
-Olof
fs/nfs/fscache.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index a01af20..3ef01f0 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -260,12 +260,11 @@ EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
if (PageFsCache(page)) {
- struct nfs_inode *nfsi = NFS_I(page->mapping->host);
struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
BUG_ON(!cookie);
dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
- cookie, page, nfsi);
+ cookie, page, NFS_I(page->mapping->host));
if (!fscache_maybe_release_page(cookie, page, gfp))
return 0;
@@ -283,13 +282,12 @@ int nfs_fscache_release_page(struct page *page, gfp_t gfp)
*/
void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
{
- struct nfs_inode *nfsi = NFS_I(inode);
struct fscache_cookie *cookie = nfs_i_fscache(inode);
BUG_ON(!cookie);
dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
- cookie, page, nfsi);
+ cookie, page, NFS_I(inode));
fscache_wait_on_page_write(cookie, page);
--
1.7.10.4
Olof Johansson <[email protected]> wrote:
> Due to commit 996a2493ed5d3a8d5db03b560fcbbf1ca3f10897 (NFS:
> Use i_writecount to control whether to get an fscache cookie in
> nfs_open(), in two instances a local variable is only used in debug
> print statements. Said statements might be compiled out, which results
> in unused variable warnings:
Yeah, Fengguang's magic compile farm has also complained about that.
David
Olof Johansson <[email protected]> wrote:
> - struct nfs_inode *nfsi = NFS_I(page->mapping->host);
> struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
>
> BUG_ON(!cookie);
> dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
> - cookie, page, nfsi);
> + cookie, page, NFS_I(page->mapping->host));
This is really the wrong fix. The null dfprintk() should use no_printk().
David