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Subject[PATCH 17/40] staging/lustre/ptlrpc: Fix race during exp_flock_hash creation
Date
From: Andriy Skulysh <Andriy_Skulysh@xyratex.com>

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()

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2835
Lustre-change: http://review.whamcloud.com/5471
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>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Prakash Surya <surya1@llnl.gov>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
---
drivers/staging/lustre/lustre/ldlm/ldlm_flock.c | 28 +++++++----------------
drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c | 8 +++++++
2 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
index 39fcdac..182773b 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
@@ -95,20 +95,12 @@ 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(hlist_unhashed(&req->l_exp_flock_hash));

@@ -121,8 +113,6 @@ 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)
@@ -250,7 +240,6 @@ 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;

CDEBUG(D_DLMTRACE, "flags %#llx owner "LPU64" pid %u mode %u start "
LPU64" end "LPU64"\n", *flags,
@@ -328,12 +317,8 @@ 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);
@@ -816,6 +801,9 @@ 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/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
index 40c58b7..ae08483 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
@@ -964,6 +964,7 @@ static cfs_hash_ops_t ldlm_export_lock_ops = {

int ldlm_init_export(struct obd_export *exp)
{
+ int rc;
exp->exp_lock_hash =
cfs_hash_create(obd_uuid2str(&exp->exp_client_uuid),
HASH_EXP_LOCK_CUR_BITS,
@@ -977,7 +978,14 @@ 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);

--
1.7.9.5


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