Merge tag 'dm-4.9-changes' of git://git.kernel.org/pub/scm/linux/kern…

…el/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - various fixes and cleanups for request-based DM core

 - add support for delaying the requeue of requests; used by DM
   multipath when all paths have failed and 'queue_if_no_path' is
   enabled

 - DM cache improvements to speedup the loading metadata and the writing
   of the hint array

 - fix potential for a dm-crypt crash on device teardown

 - remove dm_bufio_cond_resched() and just using cond_resched()

 - change DM multipath to return a reservation conflict error
   immediately; rather than failing the path and retrying (potentially
   indefinitely)

* tag 'dm-4.9-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (24 commits)
  dm mpath: always return reservation conflict without failing over
  dm bufio: remove dm_bufio_cond_resched()
  dm crypt: fix crash on exit
  dm cache metadata: switch to using the new cursor api for loading metadata
  dm array: introduce cursor api
  dm btree: introduce cursor api
  dm cache policy smq: distribute entries to random levels when switching to smq
  dm cache: speed up writing of the hint array
  dm array: add dm_array_new()
  dm mpath: delay the requeue of blk-mq requests while all paths down
  dm mpath: use dm_mq_kick_requeue_list()
  dm rq: introduce dm_mq_kick_requeue_list()
  dm rq: reduce arguments passed to map_request() and dm_requeue_original_request()
  dm rq: add DM_MAPIO_DELAY_REQUEUE to delay requeue of blk-mq requests
  dm: convert wait loops to use autoremove_wake_function()
  dm: use signal_pending_state() in dm_wait_for_completion()
  dm: rename task state function arguments
  dm: add two lockdep_assert_held() statements
  dm rq: simplify dm_old_stop_queue()
  dm mpath: check if path's request_queue is dying in activate_path()
  ...

drivers/md/dm-bufio.c

@@ -191,19 +191,6 @@ static void dm_bufio_unlock(struct dm_bufio_client *c)
 	mutex_unlock(&c->lock);
 }
 
-/*
- * FIXME Move to sched.h?
- */
-#ifdef CONFIG_PREEMPT_VOLUNTARY
-#  define dm_bufio_cond_resched()		\
-do {						\
-	if (unlikely(need_resched()))		\
-		_cond_resched();		\
-} while (0)
-#else
-#  define dm_bufio_cond_resched()                do { } while (0)
-#endif
-
 /*----------------------------------------------------------------*/
 
 /*
@@ -741,7 +728,7 @@ static void __flush_write_list(struct list_head *write_list)
 			list_entry(write_list->next, struct dm_buffer, write_list);
 		list_del(&b->write_list);
 		submit_io(b, WRITE, b->block, write_endio);
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 	blk_finish_plug(&plug);
 }
@@ -780,7 +767,7 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
 			__unlink_buffer(b);
 			return b;
 		}
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 
 	list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
@@ -791,7 +778,7 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
 			__unlink_buffer(b);
 			return b;
 		}
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 
 	return NULL;
@@ -923,7 +910,7 @@ static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
 			return;
 
 		__write_dirty_buffer(b, write_list);
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 }
 
@@ -973,7 +960,7 @@ static void __check_watermark(struct dm_bufio_client *c,
 			return;
 
 		__free_buffer_wake(b);
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 
 	if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
@@ -1170,7 +1157,7 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 				submit_io(b, READ, b->block, read_endio);
 			dm_bufio_release(b);
 
-			dm_bufio_cond_resched();
+			cond_resched();
 
 			if (!n_blocks)
 				goto flush_plug;
@@ -1291,7 +1278,7 @@ int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
 		    !test_bit(B_WRITING, &b->state))
 			__relink_lru(b, LIST_CLEAN);
 
-		dm_bufio_cond_resched();
+		cond_resched();
 
 		/*
 		 * If we dropped the lock, the list is no longer consistent,
@@ -1574,7 +1561,7 @@ static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
 				freed++;
 			if (!--nr_to_scan || ((count - freed) <= retain_target))
 				return freed;
-			dm_bufio_cond_resched();
+			cond_resched();
 		}
 	}
 	return freed;
@@ -1808,7 +1795,7 @@ static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
 		if (__try_evict_buffer(b, 0))
 			count--;
 
-		dm_bufio_cond_resched();
+		cond_resched();
 	}
 
 	dm_bufio_unlock(c);

drivers/md/dm-cache-metadata.c

@@ -140,6 +140,13 @@ struct dm_cache_metadata {
 	 * the device.
 	 */
 	bool fail_io:1;
+
+	/*
+	 * These structures are used when loading metadata.  They're too
+	 * big to put on the stack.
+	 */
+	struct dm_array_cursor mapping_cursor;
+	struct dm_array_cursor hint_cursor;
 };
 
 /*-------------------------------------------------------------------
@@ -1171,31 +1178,37 @@ static bool hints_array_available(struct dm_cache_metadata *cmd,
 		hints_array_initialized(cmd);
 }
 
-static int __load_mapping(void *context, uint64_t cblock, void *leaf)
+static int __load_mapping(struct dm_cache_metadata *cmd,
+			  uint64_t cb, bool hints_valid,
+			  struct dm_array_cursor *mapping_cursor,
+			  struct dm_array_cursor *hint_cursor,
+			  load_mapping_fn fn, void *context)
 {
 	int r = 0;
-	bool dirty;
-	__le64 value;
-	__le32 hint_value = 0;
+
+	__le64 mapping;
+	__le32 hint = 0;
+
+	__le64 *mapping_value_le;
+	__le32 *hint_value_le;
+
 	dm_oblock_t oblock;
 	unsigned flags;
-	struct thunk *thunk = context;
-	struct dm_cache_metadata *cmd = thunk->cmd;
 
-	memcpy(&value, leaf, sizeof(value));
-	unpack_value(value, &oblock, &flags);
+	dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
+	memcpy(&mapping, mapping_value_le, sizeof(mapping));
+	unpack_value(mapping, &oblock, &flags);
 
 	if (flags & M_VALID) {
-		if (thunk->hints_valid) {
-			r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
-					       cblock, &hint_value);
-			if (r && r != -ENODATA)
-				return r;
+		if (hints_valid) {
+			dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
+			memcpy(&hint, hint_value_le, sizeof(hint));
 		}
 
-		dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
-		r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
-			      dirty, le32_to_cpu(hint_value), thunk->hints_valid);
+		r = fn(context, oblock, to_cblock(cb), flags & M_DIRTY,
+		       le32_to_cpu(hint), hints_valid);
+		if (r)
+			DMERR("policy couldn't load cblock");
 	}
 
 	return r;
@@ -1205,16 +1218,60 @@ static int __load_mappings(struct dm_cache_metadata *cmd,
 			   struct dm_cache_policy *policy,
 			   load_mapping_fn fn, void *context)
 {
-	struct thunk thunk;
+	int r;
+	uint64_t cb;
+
+	bool hints_valid = hints_array_available(cmd, policy);
+
+	if (from_cblock(cmd->cache_blocks) == 0)
+		/* Nothing to do */
+		return 0;
+
+	r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
+	if (r)
+		return r;
 
-	thunk.fn = fn;
-	thunk.context = context;
+	if (hints_valid) {
+		r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
+		if (r) {
+			dm_array_cursor_end(&cmd->mapping_cursor);
+			return r;
+		}
+	}
+
+	for (cb = 0; ; cb++) {
+		r = __load_mapping(cmd, cb, hints_valid,
+				   &cmd->mapping_cursor, &cmd->hint_cursor,
+				   fn, context);
+		if (r)
+			goto out;
+
+		/*
+		 * We need to break out before we move the cursors.
+		 */
+		if (cb >= (from_cblock(cmd->cache_blocks) - 1))
+			break;
 
-	thunk.cmd = cmd;
-	thunk.respect_dirty_flags = cmd->clean_when_opened;
-	thunk.hints_valid = hints_array_available(cmd, policy);
+		r = dm_array_cursor_next(&cmd->mapping_cursor);
+		if (r) {
+			DMERR("dm_array_cursor_next for mapping failed");
+			goto out;
+		}
 
-	return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
+		if (hints_valid) {
+			r = dm_array_cursor_next(&cmd->hint_cursor);
+			if (r) {
+				DMERR("dm_array_cursor_next for hint failed");
+				goto out;
+			}
+		}
+	}
+out:
+	dm_array_cursor_end(&cmd->mapping_cursor);
+	if (hints_valid)
+		dm_array_cursor_end(&cmd->hint_cursor);
+
+	return r;
 }
 
 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
@@ -1368,10 +1425,24 @@ int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
 
 /*----------------------------------------------------------------*/
 
-static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
+static int get_hint(uint32_t index, void *value_le, void *context)
+{
+	uint32_t value;
+	struct dm_cache_policy *policy = context;
+
+	value = policy_get_hint(policy, to_cblock(index));
+	*((__le32 *) value_le) = cpu_to_le32(value);
+
+	return 0;
+}
+
+/*
+ * It's quicker to always delete the hint array, and recreate with
+ * dm_array_new().
+ */
+static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
 {
 	int r;
-	__le32 value;
 	size_t hint_size;
 	const char *policy_name = dm_cache_policy_get_name(policy);
 	const unsigned *policy_version = dm_cache_policy_get_version(policy);
@@ -1380,63 +1451,23 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po
 	    (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
 		return -EINVAL;
 
-	if (!policy_unchanged(cmd, policy)) {
-		strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
-		memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
-
-		hint_size = dm_cache_policy_get_hint_size(policy);
-		if (!hint_size)
-			return 0; /* short-circuit hints initialization */
-		cmd->policy_hint_size = hint_size;
+	strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
+	memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
 
-		if (cmd->hint_root) {
-			r = dm_array_del(&cmd->hint_info, cmd->hint_root);
-			if (r)
-				return r;
-		}
+	hint_size = dm_cache_policy_get_hint_size(policy);
+	if (!hint_size)
+		return 0; /* short-circuit hints initialization */
+	cmd->policy_hint_size = hint_size;
 
-		r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
+	if (cmd->hint_root) {
+		r = dm_array_del(&cmd->hint_info, cmd->hint_root);
 		if (r)
 			return r;
-
-		value = cpu_to_le32(0);
-		__dm_bless_for_disk(&value);
-		r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
-				    from_cblock(cmd->cache_blocks),
-				    &value, &cmd->hint_root);
-		if (r)
-			return r;
-	}
-
-	return 0;
-}
-
-static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
-{
-	struct dm_cache_metadata *cmd = context;
-	__le32 value = cpu_to_le32(hint);
-	int r;
-
-	__dm_bless_for_disk(&value);
-
-	r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
-			       from_cblock(cblock), &value, &cmd->hint_root);
-	cmd->changed = true;
-
-	return r;
-}
-
-static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
-{
-	int r;
-
-	r = begin_hints(cmd, policy);
-	if (r) {
-		DMERR("begin_hints failed");
-		return r;
 	}
 
-	return policy_walk_mappings(policy, save_hint, cmd);
+	return dm_array_new(&cmd->hint_info, &cmd->hint_root,
+			    from_cblock(cmd->cache_blocks),
+			    get_hint, policy);
 }
 
 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

drivers/md/dm-cache-policy-cleaner.c

@@ -395,7 +395,7 @@ static void init_policy_functions(struct policy *p)
 	p->policy.set_dirty = wb_set_dirty;
 	p->policy.clear_dirty = wb_clear_dirty;
 	p->policy.load_mapping = wb_load_mapping;
-	p->policy.walk_mappings = NULL;
+	p->policy.get_hint = NULL;
 	p->policy.remove_mapping = wb_remove_mapping;
 	p->policy.writeback_work = wb_writeback_work;
 	p->policy.force_mapping = wb_force_mapping;

drivers/md/dm-cache-policy-internal.h

@@ -48,10 +48,10 @@ static inline int policy_load_mapping(struct dm_cache_policy *p,
 	return p->load_mapping(p, oblock, cblock, hint, hint_valid);
 }
 
-static inline int policy_walk_mappings(struct dm_cache_policy *p,
-				      policy_walk_fn fn, void *context)
+static inline uint32_t policy_get_hint(struct dm_cache_policy *p,
+				       dm_cblock_t cblock)
 {
-	return p->walk_mappings ? p->walk_mappings(p, fn, context) : 0;
+	return p->get_hint ? p->get_hint(p, cblock) : 0;
 }
 
 static inline int policy_writeback_work(struct dm_cache_policy *p,