[PATCH 1/2] btrfs: qgroup: fix wrong qgroup metadata reserve for delayed inode

Qu Wenruo
2020-07-24T06:46:17Z

For delayed inode facility, qgroup metadata is reserved for it, and
later freed.

However we're freeing more bytes than we reserved.
In btrfs_delayed_inode_reserve_metadata():

num_bytes = btrfs_calc_metadata_size(fs_info, 1);
...
ret = btrfs_qgroup_reserve_meta_prealloc(root,
fs_info->nodesize, true);
...
if (!ret) {
node->bytes_reserved = num_bytes;

But in btrfs_delayed_inode_release_metadata():

if (qgroup_free)
btrfs_qgroup_free_meta_prealloc(node->root,
node->bytes_reserved);
else
btrfs_qgroup_convert_reserved_meta(node->root,
node->bytes_reserved);

This means, we're always releasing more qgroup metadata rsv than we have
reserved.

This won't trigger selftest warning, as btrfs qgroup metadata rsv has
extra protection against cases like quota enabled half-way.

But we still need to fix this problem any way.

This patch will use the same num_bytes for qgroup metadata rsv so we
could handle it correctly.

Fixes: f218ea6c4792 ("btrfs: delayed-inode: Remove wrong qgroup meta reservation calls")
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/delayed-inode.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index bf1595a42a98..0727b10a9a89 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -627,8 +627,7 @@ static int btrfs_delayed_inode_reserve_metadata(
*/
if (!src_rsv || (!trans->bytes_reserved &&
src_rsv->type != BTRFS_BLOCK_RSV_DELALLOC)) {
- ret = btrfs_qgroup_reserve_meta_prealloc(root,
- fs_info->nodesize, true);
+ ret = btrfs_qgroup_reserve_meta_prealloc(root, num_bytes, true);
if (ret < 0)
return ret;
ret = btrfs_block_rsv_add(root, dst_rsv, num_bytes,
--
2.27.0