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

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>

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index ae49f87b27e865325afc5b161f870877700e110d..e44d3dd17cafe2c0eb8db6cf77b6f23b7331aae3 100644 (file)
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -153,9 +153,10 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
        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 &
-           ((1U << BTRFS_ORDERED_NOCOW) | (1U << 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)
@@ -170,8 +171,13 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
                        return ERR_PTR(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 ERR_PTR(-ENOMEM);
+       }
 
        entry->file_offset = file_offset;
        entry->num_bytes = num_bytes;