FS-Cache: Provide the ability to enable/disable cookies
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 <dhowells@redhat.com
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 @@
(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 @@
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 @@
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 @@
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 @@
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 @@
volume->cache =
fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
- volume);
+ volume, true);
======================
@@ -388,7 +394,7 @@
vnode->cache =
fscache_acquire_cookie(volume->cache,
&afs_vnode_cache_object_def,
- vnode);
+ vnode, true);
=================================
@@ -404,7 +410,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
/* 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 @@
#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 @@
/* 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 @@
#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 @@
#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 @@
{
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 @@
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 2f4bc5a..fe2492d 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -27,7 +27,7 @@
{
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
_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 @@
_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 @@
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 @@
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);
@@ -464,15 +507,80 @@
EXPORT_SYMBOL(__fscache_update_cookie);
/*
+ * Disable a cookie to stop it from accepting new requests from the netfs.
+ */
+void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
+{
+ struct fscache_object *object;
+ bool awaken = false;
+
+ _enter("%p,%u", cookie, invalidate);
+
+ ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
+
+ if (atomic_read(&cookie->n_children) != 0) {
+ printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
+ cookie->def->name);
+ BUG();
+ }
+
+ 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);
+ 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). 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, int retire)
+void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
{
- struct fscache_object *object;
-
fscache_stat(&fscache_n_relinquishes);
if (retire)
fscache_stat(&fscache_n_relinquishes_retire);
@@ -487,31 +595,10 @@
cookie, cookie->def->name, cookie->netfs_data,
atomic_read(&cookie->n_active), retire);
- ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
-
- if (atomic_read(&cookie->n_children) != 0) {
- printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
- cookie->def->name);
- 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);
- spin_lock(&cookie->lock);
- hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
- fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
- }
- spin_unlock(&cookie->lock);
-
- /* Wait for cessation of activity requiring access to the netfs (when
- * n_active reaches 0).
- */
- if (!atomic_dec_and_test(&cookie->n_active))
- wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
- TASK_UNINTERRUPTIBLE);
+ __fscache_disable_cookie(cookie, retire);
/* Clear pointers back to the netfs */
cookie->netfs_data = NULL;
@@ -592,7 +679,8 @@
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 @@
.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 @@
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 @@
* 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 @@
/* 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 @@
*/
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 @@
*/
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
/* 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 @@
/* 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 @@
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 @@
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 @@
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 @@
#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 @@
};
/*
+ * 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 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 @@
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 @@
* @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 @@
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 @@
* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
__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 */