1 files changed, 95 insertions, 46 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0d6e785bcb98..d7670e2a9f39 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -245,7 +245,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
  *
  * global::fs_devs - add, remove, updates to the global list
  *
- * does not protect: manipulation of the fs_devices::devices list!
+ * does not protect: manipulation of the fs_devices::devices list in general
+ * but in mount context it could be used to exclude list modifications by eg.
+ * scan ioctl
  *
  * btrfs_device::name - renames (write side), read is RCU
  *
@@ -258,6 +260,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
  * may be used to exclude some operations from running concurrently without any
  * modifications to the list (see write_all_supers)
  *
+ * Is not required at mount and close times, because our device list is
+ * protected by the uuid_mutex at that point.
+ *
  * balance_mutex
  * -------------
  * protects balance structures (status, state) and context accessed from
@@ -602,6 +607,11 @@ static int btrfs_free_stale_devices(const char *path,
 	return ret;
 }
 
+/*
+ * This is only used on mount, and we are protected from competing things
+ * messing with our fs_devices by the uuid_mutex, thus we do not need the
+ * fs_devices->device_list_mutex here.
+ */
 static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 			struct btrfs_device *device, fmode_t flags,
 			void *holder)
@@ -1229,8 +1239,14 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 	int ret;
 
 	lockdep_assert_held(&uuid_mutex);
+	/*
+	 * The device_list_mutex cannot be taken here in case opening the
+	 * underlying device takes further locks like bd_mutex.
+	 *
+	 * We also don't need the lock here as this is called during mount and
+	 * exclusion is provided by uuid_mutex
+	 */
 
-	mutex_lock(&fs_devices->device_list_mutex);
 	if (fs_devices->opened) {
 		fs_devices->opened++;
 		ret = 0;
@@ -1238,7 +1254,6 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		list_sort(NULL, &fs_devices->devices, devid_cmp);
 		ret = open_fs_devices(fs_devices, flags, holder);
 	}
-	mutex_unlock(&fs_devices->device_list_mutex);
 
 	return ret;
 }
@@ -3231,7 +3246,7 @@ static int del_balance_item(struct btrfs_fs_info *fs_info)
 	if (!path)
 		return -ENOMEM;
 
-	trans = btrfs_start_transaction(root, 0);
+	trans = btrfs_start_transaction_fallback_global_rsv(root, 0);
 	if (IS_ERR(trans)) {
 		btrfs_free_path(path);
 		return PTR_ERR(trans);
@@ -4135,7 +4150,22 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
 	mutex_lock(&fs_info->balance_mutex);
 	if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req))
 		btrfs_info(fs_info, "balance: paused");
-	else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req))
+	/*
+	 * Balance can be canceled by:
+	 *
+	 * - Regular cancel request
+	 *   Then ret == -ECANCELED and balance_cancel_req > 0
+	 *
+	 * - Fatal signal to "btrfs" process
+	 *   Either the signal caught by wait_reserve_ticket() and callers
+	 *   got -EINTR, or caught by btrfs_should_cancel_balance() and
+	 *   got -ECANCELED.
+	 *   Either way, in this case balance_cancel_req = 0, and
+	 *   ret == -EINTR or ret == -ECANCELED.
+	 *
+	 * So here we only check the return value to catch canceled balance.
+	 */
+	else if (ret == -ECANCELED || ret == -EINTR)
 		btrfs_info(fs_info, "balance: canceled");
 	else
 		btrfs_info(fs_info, "balance: ended with status: %d", ret);
@@ -5522,6 +5552,9 @@ static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
 	atomic_set(&bbio->error, 0);
 	refcount_set(&bbio->refs, 1);
 
+	bbio->tgtdev_map = (int *)(bbio->stripes + total_stripes);
+	bbio->raid_map = (u64 *)(bbio->tgtdev_map + real_stripes);
+
 	return bbio;
 }
 
@@ -6144,8 +6177,13 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		ret = -ENOMEM;
 		goto out;
 	}
-	if (dev_replace_is_ongoing && dev_replace->tgtdev != NULL)
-		bbio->tgtdev_map = (int *)(bbio->stripes + num_alloc_stripes);
+
+	for (i = 0; i < num_stripes; i++) {
+		bbio->stripes[i].physical = map->stripes[stripe_index].physical +
+			stripe_offset + stripe_nr * map->stripe_len;
+		bbio->stripes[i].dev = map->stripes[stripe_index].dev;
+		stripe_index++;
+	}
 
 	/* build raid_map */
 	if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK && need_raid_map &&
@@ -6153,11 +6191,6 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		u64 tmp;
 		unsigned rot;
 
-		bbio->raid_map = (u64 *)((void *)bbio->stripes +
-				 sizeof(struct btrfs_bio_stripe) *
-				 num_alloc_stripes +
-				 sizeof(int) * tgtdev_indexes);
-
 		/* Work out the disk rotation on this stripe-set */
 		div_u64_rem(stripe_nr, num_stripes, &rot);
 
@@ -6171,25 +6204,13 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		if (map->type & BTRFS_BLOCK_GROUP_RAID6)
 			bbio->raid_map[(i+rot+1) % num_stripes] =
 				RAID6_Q_STRIPE;
-	}
 
-
-	for (i = 0; i < num_stripes; i++) {
-		bbio->stripes[i].physical =
-			map->stripes[stripe_index].physical +
-			stripe_offset +
-			stripe_nr * map->stripe_len;
-		bbio->stripes[i].dev =
-			map->stripes[stripe_index].dev;
-		stripe_index++;
+		sort_parity_stripes(bbio, num_stripes);
 	}
 
 	if (need_full_stripe(op))
 		max_errors = btrfs_chunk_max_errors(map);
 
-	if (bbio->raid_map)
-		sort_parity_stripes(bbio, num_stripes);
-
 	if (dev_replace_is_ongoing && dev_replace->tgtdev != NULL &&
 	    need_full_stripe(op)) {
 		handle_ops_on_dev_replace(op, &bbio, dev_replace, &num_stripes,
@@ -6261,23 +6282,18 @@ static void btrfs_end_bio(struct bio *bio)
 		atomic_inc(&bbio->error);
 		if (bio->bi_status == BLK_STS_IOERR ||
 		    bio->bi_status == BLK_STS_TARGET) {
-			unsigned int stripe_index =
-				btrfs_io_bio(bio)->stripe_index;
-			struct btrfs_device *dev;
-
-			BUG_ON(stripe_index >= bbio->num_stripes);
-			dev = bbio->stripes[stripe_index].dev;
-			if (dev->bdev) {
-				if (bio_op(bio) == REQ_OP_WRITE)
-					btrfs_dev_stat_inc_and_print(dev,
+			struct btrfs_device *dev = btrfs_io_bio(bio)->device;
+
+			ASSERT(dev->bdev);
+			if (bio_op(bio) == REQ_OP_WRITE)
+				btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_WRITE_ERRS);
-				else if (!(bio->bi_opf & REQ_RAHEAD))
-					btrfs_dev_stat_inc_and_print(dev,
+			else if (!(bio->bi_opf & REQ_RAHEAD))
+				btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_READ_ERRS);
-				if (bio->bi_opf & REQ_PREFLUSH)
-					btrfs_dev_stat_inc_and_print(dev,
+			if (bio->bi_opf & REQ_PREFLUSH)
+				btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_FLUSH_ERRS);
-			}
 		}
 	}
 
@@ -6313,13 +6329,12 @@ static void btrfs_end_bio(struct bio *bio)
 }
 
 static void submit_stripe_bio(struct btrfs_bio *bbio, struct bio *bio,
-			      u64 physical, int dev_nr)
+			      u64 physical, struct btrfs_device *dev)
 {
-	struct btrfs_device *dev = bbio->stripes[dev_nr].dev;
 	struct btrfs_fs_info *fs_info = bbio->fs_info;
 
 	bio->bi_private = bbio;
-	btrfs_io_bio(bio)->stripe_index = dev_nr;
+	btrfs_io_bio(bio)->device = dev;
 	bio->bi_end_io = btrfs_end_bio;
 	bio->bi_iter.bi_sector = physical >> 9;
 	btrfs_debug_in_rcu(fs_info,
@@ -6420,8 +6435,7 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 		else
 			bio = first_bio;
 
-		submit_stripe_bio(bbio, bio, bbio->stripes[dev_nr].physical,
-				  dev_nr);
+		submit_stripe_bio(bbio, bio, bbio->stripes[dev_nr].physical, dev);
 	}
 	btrfs_bio_counter_dec(fs_info);
 	return BLK_STS_OK;
@@ -7029,6 +7043,19 @@ out:
 	return ret;
 }
 
+static void readahead_tree_node_children(struct extent_buffer *node)
+{
+	int i;
+	const int nr_items = btrfs_header_nritems(node);
+
+	for (i = 0; i < nr_items; i++) {
+		u64 start;
+
+		start = btrfs_node_blockptr(node, i);
+		readahead_tree_block(node->fs_info, start);
+	}
+}
+
 int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_root *root = fs_info->chunk_root;
@@ -7039,6 +7066,7 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	int ret;
 	int slot;
 	u64 total_dev = 0;
+	u64 last_ra_node = 0;
 
 	path = btrfs_alloc_path();
 	if (!path)
@@ -7049,7 +7077,14 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	 * otherwise we don't need it.
 	 */
 	mutex_lock(&uuid_mutex);
-	mutex_lock(&fs_info->chunk_mutex);
+
+	/*
+	 * It is possible for mount and umount to race in such a way that
+	 * we execute this code path, but open_fs_devices failed to clear
+	 * total_rw_bytes. We certainly want it cleared before reading the
+	 * device items, so clear it here.
+	 */
+	fs_info->fs_devices->total_rw_bytes = 0;
 
 	/*
 	 * Read all device items, and then all the chunk items. All
@@ -7064,6 +7099,8 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	if (ret < 0)
 		goto error;
 	while (1) {
+		struct extent_buffer *node;
+
 		leaf = path->nodes[0];
 		slot = path->slots[0];
 		if (slot >= btrfs_header_nritems(leaf)) {
@@ -7074,6 +7111,17 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 				goto error;
 			break;
 		}
+		/*
+		 * The nodes on level 1 are not locked but we don't need to do
+		 * that during mount time as nothing else can access the tree
+		 */
+		node = path->nodes[1];
+		if (node) {
+			if (last_ra_node != node->start) {
+				readahead_tree_node_children(node);
+				last_ra_node = node->start;
+			}
+		}
 		btrfs_item_key_to_cpu(leaf, &found_key, slot);
 		if (found_key.type == BTRFS_DEV_ITEM_KEY) {
 			struct btrfs_dev_item *dev_item;
@@ -7086,7 +7134,9 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 		} else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
 			struct btrfs_chunk *chunk;
 			chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
+			mutex_lock(&fs_info->chunk_mutex);
 			ret = read_one_chunk(&found_key, leaf, chunk);
+			mutex_unlock(&fs_info->chunk_mutex);
 			if (ret)
 				goto error;
 		}
@@ -7116,7 +7166,6 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	}
 	ret = 0;
 error:
-	mutex_unlock(&fs_info->chunk_mutex);
 	mutex_unlock(&uuid_mutex);
 
 	btrfs_free_path(path);