[PATCH v2 03/16] staging: lustre: ldlm: Fix a race during FLock handling

From: James Simmons
Date: Tue Apr 12 2016 - 16:18:17 EST


From: Bruno Faccini <bruno.faccini@xxxxxxxxx>

Protect against race where lock could have been just destroyed
due to overlap, in ldlm_process_flock_lock().
Easy reproducer is BULL's NFS Locktests in pthread mode.
(http://nfsv4.bullopensource.org/tools/tests/locktest.php)

Signed-off-by: Bruno Faccini <bruno.faccini@xxxxxxxxx>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-1126
Reviewed-on: http://review.whamcloud.com/7134
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Reviewed-by: John L. Hammond <john.hammond@xxxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
---
drivers/staging/lustre/lustre/ldlm/ldlm_flock.c | 15 ++++++++++-----
1 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
index 3f97e1c..5102d78 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
@@ -520,11 +520,6 @@ ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
granted:
OBD_FAIL_TIMEOUT(OBD_FAIL_LDLM_CP_CB_WAIT, 10);

- if (lock->l_flags & LDLM_FL_DESTROYED) {
- LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
- return 0;
- }
-
if (lock->l_flags & LDLM_FL_FAILED) {
LDLM_DEBUG(lock, "client-side enqueue waking up: failed");
return -EIO;
@@ -534,6 +529,16 @@ granted:

lock_res_and_lock(lock);

+ /*
+ * Protect against race where lock could have been just destroyed
+ * due to overlap in ldlm_process_flock_lock().
+ */
+ if (lock->l_flags & LDLM_FL_DESTROYED) {
+ unlock_res_and_lock(lock);
+ LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
+ return 0;
+ }
+
/* ldlm_lock_enqueue() has already placed lock on the granted list. */
list_del_init(&lock->l_res_link);

--
1.7.1