From b4c5d8fdfff3e2b6c4fa4a5043e8946dff500f8c Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Fri, 24 Jul 2020 14:46:09 +0800
Patch-mainline: v5.10-rc1
Git-commit: b4c5d8fdfff3e2b6c4fa4a5043e8946dff500f8c
References: bsc#1177855
Subject: [PATCH] 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>
---
 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,
-- 
2.28.0