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LU-11276 ldlm: fix lock convert races
[fs/lustre-release.git] / lustre / ldlm / ldlm_inodebits.c
index c8c9fa5..095c6e5 100644 (file)
@@ -382,7 +382,10 @@ void ldlm_ibits_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
                                     union ldlm_policy_data *lpolicy)
 {
        lpolicy->l_inodebits.bits = wpolicy->l_inodebits.bits;
-       lpolicy->l_inodebits.try_bits = wpolicy->l_inodebits.try_bits;
+       /**
+        * try_bits are to be handled outside of generic write_to_local due
+        * to different behavior on a server and client.
+        */
 }
 
 void ldlm_ibits_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
@@ -424,93 +427,103 @@ int ldlm_inodebits_drop(struct ldlm_lock *lock, __u64 to_drop)
 EXPORT_SYMBOL(ldlm_inodebits_drop);
 
 /* convert single lock */
-int ldlm_cli_dropbits(struct ldlm_lock *lock, __u64 drop_bits)
+int ldlm_cli_inodebits_convert(struct ldlm_lock *lock,
+                              enum ldlm_cancel_flags cancel_flags)
 {
-       struct lustre_handle lockh;
+       struct ldlm_namespace *ns = ldlm_lock_to_ns(lock);
+       struct ldlm_lock_desc ld = { { 0 } };
+       __u64 drop_bits, new_bits;
        __u32 flags = 0;
        int rc;
 
        ENTRY;
 
-       LASSERT(drop_bits);
-       LASSERT(!lock->l_readers && !lock->l_writers);
+       check_res_locked(lock->l_resource);
 
-       LDLM_DEBUG(lock, "client lock convert START");
+       /* Lock is being converted already */
+       if (ldlm_is_converting(lock)) {
+               if (!(cancel_flags & LCF_ASYNC)) {
+                       struct l_wait_info lwi = { 0 };
 
-       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);
+                       unlock_res_and_lock(lock);
+                       l_wait_event(lock->l_waitq,
+                                    is_lock_converted(lock), &lwi);
+                       lock_res_and_lock(lock);
+               }
+               RETURN(0);
        }
 
-       /* 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);
-       }
+       /* lru_cancel may happen in parallel and call ldlm_cli_cancel_list()
+        * independently.
+        */
+       if (ldlm_is_canceling(lock))
+               RETURN(-EINVAL);
 
-       /* 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);
-       }
+       /* no need in only local convert */
+       if (lock->l_flags & (LDLM_FL_LOCAL_ONLY | LDLM_FL_CANCEL_ON_BLOCK))
+               RETURN(-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);
+       drop_bits = lock->l_policy_data.l_inodebits.cancel_bits;
+       /* no cancel bits - means that caller needs full cancel */
+       if (drop_bits == 0)
+               RETURN(-EINVAL);
+
+       new_bits = lock->l_policy_data.l_inodebits.bits & ~drop_bits;
+       /* check if all lock bits are dropped, proceed with cancel */
+       if (!new_bits)
+               RETURN(-EINVAL);
+
+       /* check if no dropped bits, consider this as successful convert */
+       if (lock->l_policy_data.l_inodebits.bits == new_bits)
+               RETURN(0);
 
-       /* 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);
-
+       ld.l_policy_data.l_inodebits.cancel_bits = drop_bits;
+       unlock_res_and_lock(lock);
+       lock->l_blocking_ast(lock, &ld, 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;
-}
+       rc = ldlm_cli_convert_req(lock, &flags, new_bits);
+       lock_res_and_lock(lock);
+       if (rc)
+               GOTO(full_cancel, rc);
+
+       /* Finally clear these bits in lock ibits */
+       ldlm_inodebits_drop(lock, drop_bits);
 
+       /* Being locked again check if lock was canceled, it is important
+        * to do and don't drop cbpending below
+        */
+       if (ldlm_is_canceling(lock))
+               GOTO(full_cancel, rc = -EINVAL);
+
+       /* also check again if more bits to be cancelled appeared */
+       if (drop_bits != lock->l_policy_data.l_inodebits.cancel_bits)
+               GOTO(clear_converting, rc = -EAGAIN);
+
+       /* 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);
+       spin_lock(&ns->ns_lock);
+       if (list_empty(&lock->l_lru))
+               ldlm_lock_add_to_lru_nolock(lock);
+       spin_unlock(&ns->ns_lock);
+
+       /* the job is done, zero the cancel_bits. If more conflicts appear,
+        * it will result in another cycle of ldlm_cli_inodebits_convert().
+        */
+full_cancel:
+       lock->l_policy_data.l_inodebits.cancel_bits = 0;
+clear_converting:
+       ldlm_clear_converting(lock);
+       RETURN(rc);
+}
 
 int ldlm_inodebits_alloc_lock(struct ldlm_lock *lock)
 {