ceph: improve fscache revalidation

There are several issues in fscache revalidation code.
- In ceph_revalidate_work(), fscache_invalidate() is called when
  fscache_check_consistency() return 0. This is complete wrong
  because 0 means cache is valid.
- Handle_cap_grant() calls ceph_queue_revalidate() if client
  already has CAP_FILE_CACHE. This code is confusing. Client
  should revalidate the cache each time it got CAP_FILE_CACHE
  anew.
- In Handle_cap_grant(), fscache_invalidate() is called if MDS
  revokes CAP_FILE_CACHE. This is inconsistency with the case
  that inode get evicted. In the later case, the cache is not
  discarded. Client may use the cache when inode is reloaded.

This patch moves the fscache revalidation into ceph_get_caps().
Client revalidates the cache after it gets CAP_FILE_CACHE.
i_rdcache_gen should keep constance while CAP_FILE_CACHE is
used. If i_fscache_gen is not equal to i_rdcache_gen, client
needs to check cache's consistency.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 0130a8592191..0168b49fb6ad 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -103,7 +103,6 @@ struct ceph_fs_client {
 
 #ifdef CONFIG_CEPH_FSCACHE
 	struct fscache_cookie *fscache;
-	struct workqueue_struct *revalidate_wq;
 #endif
 };
 
@@ -360,8 +359,7 @@ struct ceph_inode_info {
 
 #ifdef CONFIG_CEPH_FSCACHE
 	struct fscache_cookie *fscache;
-	u32 i_fscache_gen; /* sequence, for delayed fscache validate */
-	struct work_struct i_revalidate_work;
+	u32 i_fscache_gen;
 #endif
 	struct inode vfs_inode; /* at end */
 };