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| author | David Howells <dhowells@redhat.com> | 2013-08-21 17:29:38 -0400 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2013-09-06 09:17:30 +0100 |
| commit | da9803bc8812f5bd3b26baaa90e515b843c65ff7 (patch) | |
| tree | 889b39ec88863fb46606cf345eeb4fdf8a90a67e /Documentation/filesystems/caching | |
| parent | 6e4664525b1db28f8c4e1130957f70a94c19213e (diff) | |
| download | linux-da9803bc8812f5bd3b26baaa90e515b843c65ff7.tar.gz | |
FS-Cache: Add interface to check consistency of a cached object
Extend the fscache netfs API so that the netfs can ask as to whether a cache
object is up to date with respect to its corresponding netfs object:
int fscache_check_consistency(struct fscache_cookie *cookie)
This will call back to the netfs to check whether the auxiliary data associated
with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it
may also return -ENOMEM and -ERESTARTSYS.
The backends now have to implement a mandatory operation pointer:
int (*check_consistency)(struct fscache_object *object)
that corresponds to the above API call. FS-Cache takes care of pinning the
object and the cookie in memory and managing this call with respect to the
object state.
Original-author: Hongyi Jia <jiayisuse@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hongyi Jia <jiayisuse@gmail.com>
cc: Milosz Tanski <milosz@adfin.com>
Diffstat (limited to 'Documentation/filesystems/caching')
| -rw-r--r-- | Documentation/filesystems/caching/backend-api.txt | 9 | ||||
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.txt | 17 |
2 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/filesystems/caching/backend-api.txt b/Documentation/filesystems/caching/backend-api.txt index d78bab9622c6..277d1e810670 100644 --- a/Documentation/filesystems/caching/backend-api.txt +++ b/Documentation/filesystems/caching/backend-api.txt @@ -299,6 +299,15 @@ performed on the denizens of the cache. These are held in a structure of type: enough space in the cache to permit this. + (*) Check coherency state of an object [mandatory]: + + int (*check_consistency)(struct fscache_object *object) + + This method is called to have the cache check the saved auxiliary data of + the object against the netfs's idea of the state. 0 should be returned + if they're consistent and -ESTALE otherwise. -ENOMEM and -ERESTARTSYS + may also be returned. + (*) Update object [mandatory]: int (*update_object)(struct fscache_object *object) diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt index 97e6c0ecc5ef..12b344251523 100644 --- a/Documentation/filesystems/caching/netfs-api.txt +++ b/Documentation/filesystems/caching/netfs-api.txt @@ -32,7 +32,7 @@ This document contains the following sections: (9) Setting the data file size (10) Page alloc/read/write (11) Page uncaching - (12) Index and data file update + (12) Index and data file consistency (13) Miscellaneous cookie operations (14) Cookie unregistration (15) Index invalidation @@ -690,9 +690,18 @@ written to the cache and for the cache to finish with the page generally. No error is returned. -========================== -INDEX AND DATA FILE UPDATE -========================== +=============================== +INDEX AND DATA FILE CONSISTENCY +=============================== + +To find out whether auxiliary data for an object is up to data within the +cache, the following function can be called: + + int fscache_check_consistency(struct fscache_cookie *cookie) + +This will call back to the netfs to check whether the auxiliary data associated +with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it +may also return -ENOMEM and -ERESTARTSYS. To request an update of the index data for an index or other object, the following function should be called: |