Btrfs: fix wrong disk size when writing super blocks

total_size will be changed when resizing a device, and disk_total_size
will be changed if resizing is successful. Meanwhile, the on-disk super
blocks of the previous transaction might not be updated. Considering
the consistency of the metadata in the previous transaction, We should
use the size in the previous transaction to check if the super block is
beyond the boundary of the device. Fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/check-integrity.c

@@ -807,7 +807,7 @@ static int btrfsic_process_superblock_dev_mirror(
 
 	/* super block bytenr is always the unmapped device bytenr */
 	dev_bytenr = btrfs_sb_offset(superblock_mirror_num);
-	if (dev_bytenr + BTRFS_SUPER_INFO_SIZE > device->total_bytes)
+	if (dev_bytenr + BTRFS_SUPER_INFO_SIZE > device->commit_total_bytes)
 		return -1;
 	bh = __bread(superblock_bdev, dev_bytenr / 4096,
 		     BTRFS_SUPER_INFO_SIZE);

fs/btrfs/dev-replace.c

@@ -168,6 +168,8 @@ int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
 					dev_replace->srcdev->total_bytes;
 				dev_replace->tgtdev->disk_total_bytes =
 					dev_replace->srcdev->disk_total_bytes;
+				dev_replace->tgtdev->commit_total_bytes =
+					dev_replace->srcdev->commit_total_bytes;
 				dev_replace->tgtdev->bytes_used =
 					dev_replace->srcdev->bytes_used;
 			}
@@ -329,6 +331,20 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 	    args->start.tgtdev_name[0] == '\0')
 		return -EINVAL;
 
+	/*
+	 * Here we commit the transaction to make sure commit_total_bytes
+	 * of all the devices are updated.
+	 */
+	trans = btrfs_attach_transaction(root);
+	if (!IS_ERR(trans)) {
+		ret = btrfs_commit_transaction(trans, root);
+		if (ret)
+			return ret;
+	} else if (PTR_ERR(trans) != -ENOENT) {
+		return PTR_ERR(trans);
+	}
+
+	/* the disk copy procedure reuses the scrub code */
 	mutex_lock(&fs_info->volume_mutex);
 	ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
 					    args->start.srcdev_name,
@@ -539,6 +555,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 	tgt_device->total_bytes = src_device->total_bytes;
 	tgt_device->disk_total_bytes = src_device->disk_total_bytes;
+	ASSERT(list_empty(&src_device->resized_list));
+	tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 	tgt_device->bytes_used = src_device->bytes_used;
 	if (fs_info->sb->s_bdev == src_device->bdev)
 		fs_info->sb->s_bdev = tgt_device->bdev;

fs/btrfs/disk-io.c

@@ -3127,7 +3127,8 @@ static int write_dev_supers(struct btrfs_device *device,
 
 	for (i = 0; i < max_mirrors; i++) {
 		bytenr = btrfs_sb_offset(i);
-		if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
+		if (bytenr + BTRFS_SUPER_INFO_SIZE >=
+		    device->commit_total_bytes)
 			break;
 
 		if (wait) {
@@ -3444,7 +3445,7 @@ static int write_all_supers(struct btrfs_root *root, int max_mirrors)
 		btrfs_set_stack_device_type(dev_item, dev->type);
 		btrfs_set_stack_device_id(dev_item, dev->devid);
 		btrfs_set_stack_device_total_bytes(dev_item,
-						   dev->disk_total_bytes);
+						   dev->commit_total_bytes);
 		btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
 		btrfs_set_stack_device_io_align(dev_item, dev->io_align);
 		btrfs_set_stack_device_io_width(dev_item, dev->io_width);

fs/btrfs/scrub.c

@@ -2840,7 +2840,8 @@ static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
 
 	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
 		bytenr = btrfs_sb_offset(i);
-		if (bytenr + BTRFS_SUPER_INFO_SIZE > scrub_dev->total_bytes)
+		if (bytenr + BTRFS_SUPER_INFO_SIZE >
+		    scrub_dev->commit_total_bytes)
 			break;
 
 		ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,

fs/btrfs/transaction.c

@@ -1868,6 +1868,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
 	       sizeof(*root->fs_info->super_copy));
 
+	btrfs_update_commit_device_size(root->fs_info);
+
 	spin_lock(&root->fs_info->trans_lock);
 	cur_trans->state = TRANS_STATE_UNBLOCKED;
 	root->fs_info->running_transaction = NULL;

fs/btrfs/volumes.c

@@ -74,6 +74,7 @@ static struct btrfs_fs_devices *__alloc_fs_devices(void)
 	mutex_init(&fs_devs->device_list_mutex);
 
 	INIT_LIST_HEAD(&fs_devs->devices);
+	INIT_LIST_HEAD(&fs_devs->resized_devices);
 	INIT_LIST_HEAD(&fs_devs->alloc_list);
 	INIT_LIST_HEAD(&fs_devs->list);
 
@@ -154,6 +155,7 @@ static struct btrfs_device *__alloc_device(void)
 
 	INIT_LIST_HEAD(&dev->dev_list);
 	INIT_LIST_HEAD(&dev->dev_alloc_list);
+	INIT_LIST_HEAD(&dev->resized_list);
 
 	spin_lock_init(&dev->io_lock);
 
@@ -2168,6 +2170,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	device->sector_size = root->sectorsize;
 	device->total_bytes = i_size_read(bdev->bd_inode);
 	device->disk_total_bytes = device->total_bytes;
+	device->commit_total_bytes = device->total_bytes;
 	device->dev_root = root->fs_info->dev_root;
 	device->bdev = bdev;
 	device->in_fs_metadata = 1;
@@ -2364,6 +2367,8 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
 	device->sector_size = root->sectorsize;
 	device->total_bytes = srcdev->total_bytes;
 	device->disk_total_bytes = srcdev->disk_total_bytes;
+	ASSERT(list_empty(&srcdev->resized_list));
+	device->commit_total_bytes = srcdev->commit_total_bytes;
 	device->bytes_used = srcdev->bytes_used;
 	device->dev_root = fs_info->dev_root;
 	device->bdev = bdev;
@@ -2448,6 +2453,7 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_super_block *super_copy =
 		device->dev_root->fs_info->super_copy;
+	struct btrfs_fs_devices *fs_devices;
 	u64 old_total = btrfs_super_total_bytes(super_copy);
 	u64 diff = new_size - device->total_bytes;
 
@@ -2457,12 +2463,17 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 	    device->is_tgtdev_for_dev_replace)
 		return -EINVAL;
 
+	fs_devices = device->dev_root->fs_info->fs_devices;
+
 	btrfs_set_super_total_bytes(super_copy, old_total + diff);
 	device->fs_devices->total_rw_bytes += diff;
 
 	device->total_bytes = new_size;
 	device->disk_total_bytes = new_size;
 	btrfs_clear_space_info_full(device->dev_root->fs_info);
+	if (list_empty(&device->resized_list))
+		list_add_tail(&device->resized_list,
+			      &fs_devices->resized_devices);
 
 	return btrfs_update_device(trans, device);
 }
@@ -4011,8 +4022,11 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	}
 
 	lock_chunks(root);
-
 	device->disk_total_bytes = new_size;
+	if (list_empty(&device->resized_list))
+		list_add_tail(&device->resized_list,
+			      &root->fs_info->fs_devices->resized_devices);
+
 	/* Now btrfs_update_device() will change the on-disk size. */
 	ret = btrfs_update_device(trans, device);
 	if (ret) {
@@ -5993,6 +6007,7 @@ static void fill_device_from_item(struct extent_buffer *leaf,
 	device->devid = btrfs_device_id(leaf, dev_item);
 	device->disk_total_bytes = btrfs_device_total_bytes(leaf, dev_item);
 	device->total_bytes = device->disk_total_bytes;
+	device->commit_total_bytes = device->disk_total_bytes;
 	device->bytes_used = btrfs_device_bytes_used(leaf, dev_item);
 	device->type = btrfs_device_type(leaf, dev_item);
 	device->io_align = btrfs_device_io_align(leaf, dev_item);
@@ -6520,3 +6535,26 @@ int btrfs_scratch_superblock(struct btrfs_device *device)
 
 	return 0;
 }
+
+/*
+ * Update the size of all devices, which is used for writing out the
+ * super blocks.
+ */
+void btrfs_update_commit_device_size(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+	struct btrfs_device *curr, *next;
+
+	if (list_empty(&fs_devices->resized_devices))
+		return;
+
+	mutex_lock(&fs_devices->device_list_mutex);
+	lock_chunks(fs_info->dev_root);
+	list_for_each_entry_safe(curr, next, &fs_devices->resized_devices,
+				 resized_list) {
+		list_del_init(&curr->resized_list);
+		curr->commit_total_bytes = curr->disk_total_bytes;
+	}
+	unlock_chunks(fs_info->dev_root);
+	mutex_unlock(&fs_devices->device_list_mutex);
+}

fs/btrfs/volumes.h

@@ -87,6 +87,21 @@ struct btrfs_device {
 	/* physical drive uuid (or lvm uuid) */
 	u8 uuid[BTRFS_UUID_SIZE];
 
+	/*
+	 * size of the device on the current transaction
+	 *
+	 * This variant is update when committing the transaction,
+	 * and protected by device_list_mutex
+	 */
+	u64 commit_total_bytes;
+
+	/*
+	 * used to manage the device which is resized
+	 *
+	 * It is protected by chunk_lock.
+	 */
+	struct list_head resized_list;
+
 	/* for sending down flush barriers */
 	int nobarriers;
 	struct bio *flush_bio;
@@ -136,6 +151,7 @@ struct btrfs_fs_devices {
 	struct mutex device_list_mutex;
 	struct list_head devices;
 
+	struct list_head resized_devices;
 	/* devices not currently being allocated */
 	struct list_head alloc_list;
 	struct list_head list;
@@ -402,4 +418,6 @@ static inline void btrfs_dev_stat_reset(struct btrfs_device *dev,
 {
 	btrfs_dev_stat_set(dev, index, 0);
 }
+
+void btrfs_update_commit_device_size(struct btrfs_fs_info *fs_info);
 #endif