Commit 58113753 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
Browse files

Btrfs: fix unexpected cow in run_delalloc_nocow 



Fstests generic/475 provides a way to fail metadata reads while
checking if checksum exists for the inode inside run_delalloc_nocow(),
and csum_exist_in_range() interprets error (-EIO) as inode having
checksum and makes its caller enter the cow path.

In case of free space inode, this ends up with a warning in
cow_file_range().

The same problem applies to btrfs_cross_ref_exist() since it may also
read metadata in between.

With this, run_delalloc_nocow() bails out when errors occur at the two
places.

cc: <stable@vger.kernel.org> v2.6.28+
Fixes: 17d217fe ("Btrfs: fix nodatasum handling in balancing code")
Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9678c543

fs/btrfs/inode.c

+32 −5
Original line number Diff line number Diff line
@@ -1256,6 +1256,8 @@ static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info, 
		list_del(&sums->list);

		kfree(sums);

	}

	if (ret < 0)

		return ret;

	return 1;

}
@@ -1388,10 +1390,23 @@ next_slot: 
				goto out_check;

			if (btrfs_extent_readonly(fs_info, disk_bytenr))

				goto out_check;

			if (btrfs_cross_ref_exist(root, ino,

			ret = btrfs_cross_ref_exist(root, ino,

						    found_key.offset -

						  extent_offset, disk_bytenr))

						    extent_offset, disk_bytenr);

			if (ret) {

				/*

				 * ret could be -EIO if the above fails to read

				 * metadata.

				 */

				if (ret < 0) {

					if (cow_start != (u64)-1)

						cur_offset = cow_start;

					goto error;

				}



				WARN_ON_ONCE(nolock);

				goto out_check;

			}

			disk_bytenr += extent_offset;

			disk_bytenr += cur_offset - found_key.offset;

			num_bytes = min(end + 1, extent_end) - cur_offset;
@@ -1409,10 +1424,22 @@ next_slot: 
			 * this ensure that csum for a given extent are

			 * either valid or do not exist.

			 */

			if (csum_exist_in_range(fs_info, disk_bytenr,

						num_bytes)) {

			ret = csum_exist_in_range(fs_info, disk_bytenr,

						  num_bytes);

			if (ret) {

				if (!nolock)

					btrfs_end_write_no_snapshotting(root);



				/*

				 * ret could be -EIO if the above fails to read

				 * metadata.

				 */

				if (ret < 0) {

					if (cow_start != (u64)-1)

						cur_offset = cow_start;

					goto error;

				}

				WARN_ON_ONCE(nolock);

				goto out_check;

			}

			if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr)) {

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