btrfs: qgroup: fix wrong qgroup metadata reserve for delayed inode

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")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index bf1595a42a988c4a1e94140d8ba8dc2d026aa047..0727b10a9a8971a5c8711dce68aca2dc43cbc00d 100644 (file)
--- 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,