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>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 7bdf7d5..6f60d0a 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2393,6 +2393,9 @@
snap_rwsem_locked = true;
}
*got = need | (have & want);
+ if ((need & CEPH_CAP_FILE_RD) &&
+ !(*got & CEPH_CAP_FILE_CACHE))
+ ceph_disable_fscache_readpage(ci);
__take_cap_refs(ci, *got, true);
ret = 1;
}
@@ -2554,6 +2557,9 @@
break;
}
+ if ((_got & CEPH_CAP_FILE_RD) && (_got & CEPH_CAP_FILE_CACHE))
+ ceph_fscache_revalidate_cookie(ci);
+
*got = _got;
return 0;
}
@@ -2795,7 +2801,6 @@
bool writeback = false;
bool queue_trunc = false;
bool queue_invalidate = false;
- bool queue_revalidate = false;
bool deleted_inode = false;
bool fill_inline = false;
@@ -2837,8 +2842,6 @@
ci->i_rdcache_revoking = ci->i_rdcache_gen;
}
}
-
- ceph_fscache_invalidate(inode);
}
/* side effects now are allowed */
@@ -2880,11 +2883,6 @@
}
}
- /* Do we need to revalidate our fscache cookie. Don't bother on the
- * first cache cap as we already validate at cookie creation time. */
- if ((issued & CEPH_CAP_FILE_CACHE) && ci->i_rdcache_gen > 1)
- queue_revalidate = true;
-
if (newcaps & CEPH_CAP_ANY_RD) {
/* ctime/mtime/atime? */
ceph_decode_timespec(&mtime, &grant->mtime);
@@ -2995,8 +2993,6 @@
if (queue_trunc)
ceph_queue_vmtruncate(inode);
- else if (queue_revalidate)
- ceph_queue_revalidate(inode);
if (writeback)
/*