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features/locks: Remove stale entrylk objects from 'blocked_locks' list

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* In the event of a DISCONNECT from a client, as part of cleanup,
  entrylk objects are not removed from the blocked_locks list before
  being unref'd and freed, causing the brick process to crash at
  some point when the (now) stale object is accessed again in the list.

* Also during cleanup, it is pointless to try and grant lock to a
  previously blocked entrylk (say L1) as part of releasing another
  conflicting lock (L2), (which is a side-effect of L1 not being
  deleted from blocked_locks list before grant_blocked_entry_locks()
  in cleanup) if L1 is also associated with the DISCONNECTing client.
  This patch fixes the problem.

Change-Id: I3d684c6bafc7e6db89ba68f0a2ed1dcb333791c6
BUG: 1089470
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/7560
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
This commit is contained in:
Krutika Dhananjay 2014-04-24 16:37:05 +05:30 committed by Anand Avati
parent 0af287791f
commit 6a188c6b2c
2 changed files with 48 additions and 4 deletions
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50
xlators/features/locks/src/entrylk.c
View File

@ -715,15 +715,16 @@ pl_entrylk_client_cleanup (xlator_t *this, pl_ctx_t *ctx)
pl_inode_t *pinode = NULL;
struct list_head released;
struct list_head unwind;
INIT_LIST_HEAD (&released);
INIT_LIST_HEAD (&unwind);
pthread_mutex_lock (&ctx->lock);
{
list_for_each_entry_safe (l, tmp, &ctx->entrylk_lockers,
client_list) {
list_del_init (&l->client_list);
list_add_tail (&l->client_list, &released);
pl_entrylk_log_cleanup (l);
@ -731,19 +732,62 @@ pl_entrylk_client_cleanup (xlator_t *this, pl_ctx_t *ctx)
pthread_mutex_lock (&pinode->mutex);
{
list_del_init (&l->domain_list);
/* If the entrylk object is part of granted list but not
* blocked list, then perform the following actions:
* i. delete the object from granted list;
* ii. grant other locks (from other clients) that may
* have been blocked on this entrylk; and
* iii. unref the object.
*
* If the entrylk object (L1) is part of both granted
* and blocked lists, then this means that a parallel
* unlock on another entrylk (L2 say) may have 'granted'
* L1 and added it to 'granted' list in
* __grant_blocked_entry_locks() (although using the
* 'blocked_locks' member). In that case, the cleanup
* codepath must try and grant other overlapping
* blocked entrylks from other clients, now that L1 is
* out of their way and then unref L1 in the end, and
* leave it to the other thread (the one executing
* unlock codepath) to unwind L1's frame, delete it from
* blocked_locks list, and perform the last unref on L1.
*
* If the entrylk object (L1) is part of blocked list
* only, the cleanup code path must:
* i. delete it from the blocked_locks list inside
* this critical section,
* ii. unwind its frame with EAGAIN,
* iii. try and grant blocked entry locks from other
* clients that were otherwise grantable, but were
* blocked to avoid leaving L1 to starve forever.
* iv. unref the object.
*/
if (!list_empty (&l->domain_list)) {
list_del_init (&l->domain_list);
list_add_tail (&l->client_list,
&released);
} else {
list_del_init (&l->blocked_locks);
list_add_tail (&l->client_list,
&unwind);
}
}
pthread_mutex_unlock (&pinode->mutex);
}
}
pthread_mutex_unlock (&ctx->lock);
list_for_each_entry_safe (l, tmp, &released, client_list) {
list_for_each_entry_safe (l, tmp, &unwind, client_list) {
list_del_init (&l->client_list);
if (l->frame)
STACK_UNWIND_STRICT (entrylk, l->frame, -1, EAGAIN,
NULL);
list_add_tail (&l->client_list, &released);
}
list_for_each_entry_safe (l, tmp, &released, client_list) {
list_del_init (&l->client_list);
pinode = l->pinode;

2
xlators/features/locks/src/inodelk.c
View File

@ -26,7 +26,7 @@
inline void
__delete_inode_lock (pl_inode_lock_t *lock)
{
list_del (&lock->list);
list_del_init (&lock->list);
}
static inline void