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authorDavid Howells <dhowells@redhat.com>2013-09-21 00:09:31 +0100
committerDavid Howells <dhowells@redhat.com>2013-09-27 18:40:25 +0100
commit94d30ae90a00cafe686c1057be57f4885f963abf (patch)
tree2a4f927bcaf87e988f4f180d0a011856064186b5 /include/linux/fscache-cache.h
parent8fb883f3e30065529e4f35d4b4f355193dcdb7a2 (diff)
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
Diffstat (limited to 'include/linux/fscache-cache.h')
-rw-r--r--include/linux/fscache-cache.h31
1 files changed, 1 insertions, 30 deletions
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 96a2b66f5968..771484993ca7 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 */