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Commit d6397bae authored by Chris Ball's avatar Chris Ball Committed by Chris Mason
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Btrfs: When shrinking, only update disk size on success 



Previously, we updated a device's size prior to attempting a shrink
operation.  This patch moves the device resizing logic to only happen if
the shrink completes successfully.  In the process, it introduces a new
field to btrfs_device -- disk_total_bytes -- to track the on-disk size.

Signed-off-by: default avatarChris Ball <cjb@laptop.org>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 59bc5c75

fs/btrfs/volumes.c

+24 −11
Original line number Diff line number Diff line
@@ -1543,7 +1543,7 @@ static noinline int btrfs_update_device(struct btrfs_trans_handle *trans, 
	btrfs_set_device_io_align(leaf, dev_item, device->io_align);

	btrfs_set_device_io_width(leaf, dev_item, device->io_width);

	btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);

	btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);

	btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);

	btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);

	btrfs_mark_buffer_dirty(leaf);
@@ -1940,14 +1940,6 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) 
	device->total_bytes = new_size;

	if (device->writeable)

		device->fs_devices->total_rw_bytes -= diff;

	ret = btrfs_update_device(trans, device);

	if (ret) {

		unlock_chunks(root);

		btrfs_end_transaction(trans, root);

		goto done;

	}

	WARN_ON(diff > old_total);

	btrfs_set_super_total_bytes(super_copy, old_total - diff);

	unlock_chunks(root);

	btrfs_end_transaction(trans, root);
@@ -1979,7 +1971,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) 
		length = btrfs_dev_extent_length(l, dev_extent);



		if (key.offset + length <= new_size)

			goto done;

			break;



		chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);

		chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
@@ -1992,6 +1984,26 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) 
			goto done;

	}



	/* Shrinking succeeded, else we would be at "done". */

	trans = btrfs_start_transaction(root, 1);

	if (!trans) {

		ret = -ENOMEM;

		goto done;

	}

	lock_chunks(root);



	device->disk_total_bytes = new_size;

	/* Now btrfs_update_device() will change the on-disk size. */

	ret = btrfs_update_device(trans, device);

	if (ret) {

		unlock_chunks(root);

		btrfs_end_transaction(trans, root);

		goto done;

	}

	WARN_ON(diff > old_total);

	btrfs_set_super_total_bytes(super_copy, old_total - diff);

	unlock_chunks(root);

	btrfs_end_transaction(trans, root);

done:

	btrfs_free_path(path);

	return ret;
@@ -3076,7 +3088,8 @@ static int fill_device_from_item(struct extent_buffer *leaf, 
	unsigned long ptr;



	device->devid = btrfs_device_id(leaf, dev_item);

	device->total_bytes = btrfs_device_total_bytes(leaf, dev_item);

	device->disk_total_bytes = btrfs_device_total_bytes(leaf, dev_item);

	device->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);

fs/btrfs/volumes.h

+3 −0
Original line number Diff line number Diff line
@@ -61,6 +61,9 @@ struct btrfs_device { 
	/* size of the device */

	u64 total_bytes;



	/* size of the disk */

	u64 disk_total_bytes;



	/* bytes used */

	u64 bytes_used;