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authorLinus Torvalds <torvalds@linux-foundation.org>2013-09-09 09:13:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-09 09:13:22 -0700
commit6cccc7d3012344371a897ecdd1a1398286a6ee8a (patch)
tree64d7c301739abb303e15f108df4c00e8da227caf /Documentation
parent255ae3fbd298f312ce47ff0c7ee9bb6ad002e0f0 (diff)
parenta8d436f015b627a55ec3b1d15f13d6ab92dd892b (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
Pull ceph updates from Sage Weil: "This includes both the first pile of Ceph patches (which I sent to torvalds@vger, sigh) and a few new patches that add support for fscache for Ceph. That includes a few fscache core fixes that David Howells asked go through the Ceph tree. (Thanks go to Milosz Tanski for putting this feature together) This first batch of patches (included here) had (has) several important RBD bug fixes, hole punch support, several different cleanups in the page cache interactions, improvements in the truncate code (new truncate mutex to avoid shenanigans with i_mutex), and a series of fixes in the synchronous striping read/write code. On top of that is a random collection of small fixes all across the tree (error code checks and error path cleanup, obsolete wq flags, etc)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (43 commits) ceph: use d_invalidate() to invalidate aliases ceph: remove ceph_lookup_inode() ceph: trivial buildbot warnings fix ceph: Do not do invalidate if the filesystem is mounted nofsc ceph: page still marked private_2 ceph: ceph_readpage_to_fscache didn't check if marked ceph: clean PgPrivate2 on returning from readpages ceph: use fscache as a local presisent cache fscache: Netfs function for cleanup post readpages FS-Cache: Fix heading in documentation CacheFiles: Implement interface to check cache consistency FS-Cache: Add interface to check consistency of a cached object rbd: fix null dereference in dout rbd: fix buffer size for writes to images with snapshots libceph: use pg_num_mask instead of pgp_num_mask for pg.seed calc rbd: fix I/O error propagation for reads ceph: use vfs __set_page_dirty_nobuffers interface instead of doing it inside filesystem ceph: allow sync_read/write return partial successed size of read/write. ceph: fix bugs about handling short-read for sync read mode. ceph: remove useless variable revoked_rdcache ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/caching/backend-api.txt9
-rw-r--r--Documentation/filesystems/caching/netfs-api.txt37
2 files changed, 40 insertions, 6 deletions
diff --git a/Documentation/filesystems/caching/backend-api.txt b/Documentation/filesystems/caching/backend-api.txt
index d78bab9622c..277d1e81067 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 97e6c0ecc5e..11a0a40ce44 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
@@ -433,7 +433,7 @@ to the caller. The attribute adjustment excludes read and write operations.
=====================
-PAGE READ/ALLOC/WRITE
+PAGE ALLOC/READ/WRITE
=====================
And the sixth step is to store and retrieve pages in the cache. There are
@@ -499,7 +499,7 @@ Else if there's a copy of the page resident in the cache:
(*) An argument that's 0 on success or negative for an error code.
If an error occurs, it should be assumed that the page contains no usable
- data.
+ data. fscache_readpages_cancel() may need to be called.
end_io_func() will be called in process context if the read is results in
an error, but it might be called in interrupt context if the read is
@@ -623,6 +623,22 @@ some of the pages being read and some being allocated. Those pages will have
been marked appropriately and will need uncaching.
+CANCELLATION OF UNREAD PAGES
+----------------------------
+
+If one or more pages are passed to fscache_read_or_alloc_pages() but not then
+read from the cache and also not read from the underlying filesystem then
+those pages will need to have any marks and reservations removed. This can be
+done by calling:
+
+ void fscache_readpages_cancel(struct fscache_cookie *cookie,
+ struct list_head *pages);
+
+prior to returning to the caller. The cookie argument should be as passed to
+fscache_read_or_alloc_pages(). Every page in the pages list will be examined
+and any that have PG_fscache set will be uncached.
+
+
==============
PAGE UNCACHING
==============
@@ -690,9 +706,18 @@ 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: