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Diffstat (limited to 'xlators/features/locks/src/entrylk.c')
-rw-r--r--xlators/features/locks/src/entrylk.c52
1 files changed, 48 insertions, 4 deletions
diff --git a/xlators/features/locks/src/entrylk.c b/xlators/features/locks/src/entrylk.c
index dc86512..8496d9d 100644
--- a/xlators/features/locks/src/entrylk.c
+++ b/xlators/features/locks/src/entrylk.c
@@ -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);
@@ -731,25 +732,68 @@ 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;
dom = get_domain (pinode, l->volume);
- grant_blocked_inode_locks (this, pinode, dom);
+ grant_blocked_entry_locks (this, pinode, dom);
pthread_mutex_lock (&pinode->mutex);
{