[PATCH 10/10] staging/lustre/xattr: xattr data may be gone with lock held

[green]

From: Lai Siyao <lai.siyao@xxxxxxxxx>

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

Signed-off-by: Lai Siyao <lai.siyao@xxxxxxxxx>
Reviewed-on: http://review.whamcloud.com/12952
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3544
Reviewed-by: Bobi Jam <bobijam@xxxxxxxxxxx>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@xxxxxxxxx>
Signed-off-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
---
 drivers/staging/lustre/lustre/llite/xattr_cache.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/xattr_cache.c b/drivers/staging/lustre/lustre/llite/xattr_cache.c
index da190f9..69ea92a 100644
--- a/drivers/staging/lustre/lustre/llite/xattr_cache.c
+++ b/drivers/staging/lustre/lustre/llite/xattr_cache.c
@@ -295,13 +295,18 @@ static int ll_xattr_find_get_lock(struct inode *inode,
 
 
 	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. */
-- 
2.1.0

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