btrfs: fix qgroup reservation leak on failure to allocate ordered extent

[ Upstream commit 1f2889f5594a2bc4c6a52634c4a51b93e785def5 ]

If we fail to allocate an ordered extent for a COW write we end up leaking
a qgroup data reservation since we called btrfs_qgroup_release_data() but
we didn't call btrfs_qgroup_free_refroot() (which would happen when
running the respective data delayed ref created by ordered extent
completion or when finishing the ordered extent in case an error happened).

So make sure we call btrfs_qgroup_free_refroot() if we fail to allocate an
ordered extent for a COW write.

Fixes: 7dbeaad0af7d ("btrfs: change timing for qgroup reserved space for ordered extents to fix reserved space leak")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[ adjust to code movements ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 1b2af4785c0e2c4c2a8ae7b7a27cee781bcf6632..69fd4f9d840b56ea61a1fdc2ec51d2c65e89d1c1 100644 (file)
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -173,9 +173,10 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
        struct btrfs_ordered_extent *entry;
        int ret;
        u64 qgroup_rsv = 0;
+       const bool is_nocow = (flags &
+              ((1U << BTRFS_ORDERED_NOCOW) | (1U << BTRFS_ORDERED_PREALLOC)));
 
-       if (flags &
-           ((1 << BTRFS_ORDERED_NOCOW) | (1 << BTRFS_ORDERED_PREALLOC))) {
+       if (is_nocow) {
                /* For nocow write, we can release the qgroup rsv right now */
                ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes, &qgroup_rsv);
                if (ret < 0)
@@ -191,8 +192,13 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                        return ret;
        }
        entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
-       if (!entry)
+       if (!entry) {
+               if (!is_nocow)
+                       btrfs_qgroup_free_refroot(inode->root->fs_info,
+                                                 btrfs_root_id(inode->root),
+                                                 qgroup_rsv, BTRFS_QGROUP_RSV_DATA);
                return -ENOMEM;
+       }
 
        entry->file_offset = file_offset;
        entry->num_bytes = num_bytes;