LU-2835 ptlrpc: Fix race during exp_flock_hash creation

During race exp_flock_hash can be created 2 times.
It is created & assigned without any lock.

Move hash initialization from ldlm_flock_blocking_link()
to ldlm_init_export()

Xyratex-bug-id: MRP-855
Signed-off-by: Andriy Skulysh <Andriy_Skulysh@xyratex.com>
Reviewed-by: Alexander Boyko <Alexander_Boyko@xyratex.com>
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@xyratex.com>
Tested-by: Kyrylo Shatskyy <kyrylo_shatskyy@xyratex.com>
Change-Id: Iaec171eb628396b69dede973260a59ac345b7e8c
Reviewed-on: http://review.whamcloud.com/5471
Tested-by: Hudson
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Prakash Surya <surya1@llnl.gov>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/ldlm/ldlm_flock.c b/lustre/ldlm/ldlm_flock.c
index 5b40b3e..a765cc7 100644 (file)
--- a/lustre/ldlm/ldlm_flock.c
+++ b/lustre/ldlm/ldlm_flock.c
@@ -100,20 +100,12 @@ ldlm_flocks_overlap(struct ldlm_lock *lock, struct ldlm_lock *new)
                 lock->l_policy_data.l_flock.start));
 }
 
-static inline int ldlm_flock_blocking_link(struct ldlm_lock *req,
-                                          struct ldlm_lock *lock)
+static inline void ldlm_flock_blocking_link(struct ldlm_lock *req,
+                                           struct ldlm_lock *lock)
 {
-       int rc = 0;
-
         /* For server only */
         if (req->l_export == NULL)
-               return 0;
-
-       if (unlikely(req->l_export->exp_flock_hash == NULL)) {
-               rc = ldlm_init_flock_export(req->l_export);
-               if (rc)
-                       goto error;
-       }
+               return;
 
        LASSERT(cfs_hlist_unhashed(&req->l_exp_flock_hash));
 
@@ -126,8 +118,6 @@ static inline int ldlm_flock_blocking_link(struct ldlm_lock *req,
        cfs_hash_add(req->l_export->exp_flock_hash,
                     &req->l_policy_data.l_flock.owner,
                     &req->l_exp_flock_hash);
-error:
-       return rc;
 }
 
 static inline void ldlm_flock_blocking_unlink(struct ldlm_lock *req)
@@ -258,7 +248,6 @@ ldlm_process_flock_lock(struct ldlm_lock *req, __u64 *flags, int first_enq,
         int overlaps = 0;
         int splitted = 0;
         const struct ldlm_callback_suite null_cbs = { NULL };
-       int rc;
         ENTRY;
 
        CDEBUG(D_DLMTRACE, "flags %#llx owner "LPU64" pid %u mode %u start "
@@ -337,12 +326,8 @@ reprocess:
 
                        /* add lock to blocking list before deadlock
                         * check to prevent race */
-                       rc = ldlm_flock_blocking_link(req, lock);
-                       if (rc) {
-                               ldlm_flock_destroy(req, mode, *flags);
-                               *err = rc;
-                               RETURN(LDLM_ITER_STOP);
-                       }
+                       ldlm_flock_blocking_link(req, lock);
+
                        if (ldlm_flock_deadlock(req, lock)) {
                                ldlm_flock_blocking_unlink(req);
                                ldlm_flock_destroy(req, mode, *flags);
@@ -862,6 +847,9 @@ static cfs_hash_ops_t ldlm_export_flock_ops = {
 
 int ldlm_init_flock_export(struct obd_export *exp)
 {
+       if( strcmp(exp->exp_obd->obd_type->typ_name, LUSTRE_MDT_NAME) != 0)
+               RETURN(0);
+
        exp->exp_flock_hash =
                cfs_hash_create(obd_uuid2str(&exp->exp_client_uuid),
                                HASH_EXP_LOCK_CUR_BITS,

diff --git a/lustre/ldlm/ldlm_lockd.c b/lustre/ldlm/ldlm_lockd.c
index 2f11b93..1cfd813 100644 (file)
--- a/lustre/ldlm/ldlm_lockd.c
+++ b/lustre/ldlm/ldlm_lockd.c
@@ -2775,6 +2775,7 @@ static cfs_hash_ops_t ldlm_export_lock_ops = {
 
 int ldlm_init_export(struct obd_export *exp)
 {
+       int rc;
         ENTRY;
 
         exp->exp_lock_hash =
@@ -2790,7 +2791,14 @@ int ldlm_init_export(struct obd_export *exp)
         if (!exp->exp_lock_hash)
                 RETURN(-ENOMEM);
 
+       rc = ldlm_init_flock_export(exp);
+       if (rc)
+               GOTO(err, rc);
+
         RETURN(0);
+err:
+       ldlm_destroy_export(exp);
+       RETURN(rc);
 }
 EXPORT_SYMBOL(ldlm_init_export);