LU-3544 xattr: xattr data may be gone with lock held

Xattr cached data may be gone, but lock still held, in this case,
refetch xattr from server, otherwise client will return error.

This patch is backported from the following one:
Lustre-commit: Id6fbbef339fea540728b181b2ae91799b8151fbd
Lustre-Change: http://review.whamcloud.com/10693

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: Ide3c2686a7a9f118c4c44fc5de8eb5670011f112
Reviewed-on: http://review.whamcloud.com/12952
Tested-by: Jenkins
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/llite/xattr_cache.c b/lustre/llite/xattr_cache.c
index fd32da0..413ee9f 100644 (file)
--- a/lustre/llite/xattr_cache.c
+++ b/lustre/llite/xattr_cache.c
@@ -325,13 +325,18 @@ static int ll_xattr_find_get_lock(struct inode *inode,
        ENTRY;
 
        mutex_lock(&lli->lli_xattrs_enq_lock);
-       /* Try matching first. */
-       mode = ll_take_md_lock(inode, MDS_INODELOCK_XATTR, &lockh, 0, LCK_PR);
-       if (mode != 0) {
-               /* fake oit in mdc_revalidate_lock() manner */
-               oit->d.lustre.it_lock_handle = lockh.cookie;
-               oit->d.lustre.it_lock_mode = mode;
-               goto out;
+       /* inode may have been shrunk and recreated, so data is gone, match lock
+        * only when data exists. */
+       if (ll_xattr_cache_valid(lli)) {
+               /* Try matching first. */
+               mode = ll_take_md_lock(inode, MDS_INODELOCK_XATTR, &lockh, 0,
+                                       LCK_PR);
+               if (mode != 0) {
+                       /* fake oit in mdc_revalidate_lock() manner */
+                       oit->d.lustre.it_lock_handle = lockh.cookie;
+                       oit->d.lustre.it_lock_mode = mode;
+                       goto out;
+               }
        }
 
        /* Enqueue if the lock isn't cached locally. */