#include "ldlm_internal.h"
#ifdef HAVE_SERVER_SUPPORT
+
/**
* Determine if the lock is compatible with all locks on the queue.
*
check_res_locked(res);
if (intention == LDLM_PROCESS_RESCAN) {
- *err = ELDLM_LOCK_ABORTED;
+ struct list_head *bl_list;
+
+ if (*flags & LDLM_FL_BLOCK_NOWAIT) {
+ bl_list = NULL;
+ *err = ELDLM_LOCK_WOULDBLOCK;
+ } else {
+ bl_list = work_list;
+ *err = ELDLM_LOCK_ABORTED;
+ }
LASSERT(lock->l_policy_data.l_inodebits.bits != 0);
- rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, NULL);
+ /* It is possible that some of granted locks was not canceled
+ * but converted and is kept in granted queue. So there is
+ * a window where lock with 'ast_sent' might become granted
+ * again. Meanwhile a new lock may appear in that window and
+ * conflicts with the converted lock so the following scenario
+ * is possible:
+ *
+ * 1) lock1 conflicts with lock2
+ * 2) bl_ast was sent for lock2
+ * 3) lock3 comes and conflicts with lock2 too
+ * 4) no bl_ast sent because lock2->l_bl_ast_sent is 1
+ * 5) lock2 was converted for lock1 but not for lock3
+ * 6) lock1 granted, lock3 still is waiting for lock2, but
+ * there will never be another bl_ast for that
+ *
+ * To avoid this scenario the work_list is used below to collect
+ * any blocked locks from granted queue during every reprocess
+ * and bl_ast will be sent if needed.
+ */
+ rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock,
+ bl_list);
if (!rc)
RETURN(LDLM_ITER_STOP);
rc = ldlm_inodebits_compat_queue(&res->lr_waiting, lock, NULL);
wpolicy->l_inodebits.try_bits = lpolicy->l_inodebits.try_bits;
}
-int ldlm_inodebits_drop(struct ldlm_lock *lock, __u64 to_drop)
+/**
+ * Attempt to convert already granted IBITS lock with several bits set to
+ * a lock with less bits (downgrade).
+ *
+ * Such lock conversion is used to keep lock with non-blocking bits instead of
+ * cancelling it, introduced for better support of DoM files.
+ */
+int ldlm_inodebits_drop(struct ldlm_lock *lock, __u64 to_drop)
{
ENTRY;
/* Just return if there are no conflicting bits */
if ((lock->l_policy_data.l_inodebits.bits & to_drop) == 0) {
- LDLM_WARN(lock, "try to drop unset bits %#llx/%#llx\n",
+ LDLM_WARN(lock, "try to drop unset bits %#llx/%#llx",
lock->l_policy_data.l_inodebits.bits, to_drop);
/* nothing to do */
RETURN(0);
RETURN(0);
}
EXPORT_SYMBOL(ldlm_inodebits_drop);
+
+/* convert single lock */
+int ldlm_cli_dropbits(struct ldlm_lock *lock, __u64 drop_bits)
+{
+ struct lustre_handle lockh;
+ __u32 flags = 0;
+ int rc;
+
+ ENTRY;
+
+ LASSERT(drop_bits);
+ LASSERT(!lock->l_readers && !lock->l_writers);
+
+ LDLM_DEBUG(lock, "client lock convert START");
+
+ ldlm_lock2handle(lock, &lockh);
+ lock_res_and_lock(lock);
+ /* check if all bits are blocked */
+ if (!(lock->l_policy_data.l_inodebits.bits & ~drop_bits)) {
+ unlock_res_and_lock(lock);
+ /* return error to continue with cancel */
+ GOTO(exit, rc = -EINVAL);
+ }
+
+ /* check if no common bits, consider this as successful convert */
+ if (!(lock->l_policy_data.l_inodebits.bits & drop_bits)) {
+ unlock_res_and_lock(lock);
+ GOTO(exit, rc = 0);
+ }
+
+ /* check if there is race with cancel */
+ if (ldlm_is_canceling(lock) || ldlm_is_cancel(lock)) {
+ unlock_res_and_lock(lock);
+ GOTO(exit, rc = -EINVAL);
+ }
+
+ /* clear cbpending flag early, it is safe to match lock right after
+ * client convert because it is downgrade always.
+ */
+ ldlm_clear_cbpending(lock);
+ ldlm_clear_bl_ast(lock);
+
+ /* If lock is being converted already, check drop bits first */
+ if (ldlm_is_converting(lock)) {
+ /* raced lock convert, lock inodebits are remaining bits
+ * so check if they are conflicting with new convert or not.
+ */
+ if (!(lock->l_policy_data.l_inodebits.bits & drop_bits)) {
+ unlock_res_and_lock(lock);
+ GOTO(exit, rc = 0);
+ }
+ /* Otherwise drop new conflicting bits in new convert */
+ }
+ ldlm_set_converting(lock);
+ /* from all bits of blocking lock leave only conflicting */
+ drop_bits &= lock->l_policy_data.l_inodebits.bits;
+ /* save them in cancel_bits, so l_blocking_ast will know
+ * which bits from the current lock were dropped. */
+ lock->l_policy_data.l_inodebits.cancel_bits = drop_bits;
+ /* Finally clear these bits in lock ibits */
+ ldlm_inodebits_drop(lock, drop_bits);
+ unlock_res_and_lock(lock);
+ /* Finally call cancel callback for remaining bits only.
+ * It is important to have converting flag during that
+ * so blocking_ast callback can distinguish convert from
+ * cancels.
+ */
+ if (lock->l_blocking_ast)
+ lock->l_blocking_ast(lock, NULL, lock->l_ast_data,
+ LDLM_CB_CANCELING);
+
+ /* now notify server about convert */
+ rc = ldlm_cli_convert(lock, &flags);
+ if (rc) {
+ lock_res_and_lock(lock);
+ if (ldlm_is_converting(lock)) {
+ ldlm_clear_converting(lock);
+ ldlm_set_cbpending(lock);
+ ldlm_set_bl_ast(lock);
+ }
+ unlock_res_and_lock(lock);
+ GOTO(exit, rc);
+ }
+ EXIT;
+exit:
+ LDLM_DEBUG(lock, "client lock convert END");
+ return rc;
+}
git://git.whamcloud.com / fs / lustre-release.git / blobdiff