From: Qu Wenruo wqu@suse.com
commit bab32fc069ce8829c416e8737c119f62a57970f9 upstream.
[BUG] Under the following case with qgroup enabled, if some error happened after we have reserved delalloc space, then in error handling path, we could cause qgroup data space leakage:
From btrfs_truncate_block() in inode.c:
ret = btrfs_delalloc_reserve_space(inode, &data_reserved, block_start, blocksize); if (ret) goto out;
again: page = find_or_create_page(mapping, index, mask); if (!page) { btrfs_delalloc_release_space(inode, data_reserved, block_start, blocksize, true); btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, true); ret = -ENOMEM; goto out; }
[CAUSE] In the above case, btrfs_delalloc_reserve_space() will call btrfs_qgroup_reserve_data() and mark the io_tree range with EXTENT_QGROUP_RESERVED flag.
In the error handling path, we have the following call stack: btrfs_delalloc_release_space() |- btrfs_free_reserved_data_space() |- btrsf_qgroup_free_data() |- __btrfs_qgroup_release_data(reserved=@reserved, free=1) |- qgroup_free_reserved_data(reserved=@reserved) |- clear_record_extent_bits(); |- freed += changeset.bytes_changed;
However due to a completion bug, qgroup_free_reserved_data() will clear EXTENT_QGROUP_RESERVED flag in BTRFS_I(inode)->io_failure_tree, other than the correct BTRFS_I(inode)->io_tree. Since io_failure_tree is never marked with that flag, btrfs_qgroup_free_data() will not free any data reserved space at all, causing a leakage.
This type of error handling can only be triggered by errors outside of qgroup code. So EDQUOT error from qgroup can't trigger it.
[FIX] Fix the wrong target io_tree.
Reported-by: Josef Bacik josef@toxicpanda.com Fixes: bc42bda22345 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges") CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Nikolay Borisov nborisov@suse.com Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/qgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3469,7 +3469,7 @@ static int qgroup_free_reserved_data(str * EXTENT_QGROUP_RESERVED, we won't double free. * So not need to rush. */ - ret = clear_record_extent_bits(&BTRFS_I(inode)->io_failure_tree, + ret = clear_record_extent_bits(&BTRFS_I(inode)->io_tree, free_start, free_start + free_len - 1, EXTENT_QGROUP_RESERVED, &changeset); if (ret < 0)