Patch "btrfs: ref-verify: free ref cache before clearing mount opt" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    btrfs: ref-verify: free ref cache before clearing mount opt

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-ref-verify-free-ref-cache-before-clearing-moun.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e4cb568eba3cb6ab1d80757b3e9d12002bc8d847
Author: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Date:   Wed Jan 3 13:31:27 2024 +0300

    btrfs: ref-verify: free ref cache before clearing mount opt
    
    [ Upstream commit f03e274a8b29d1d1c1bbd7f764766cb5ca537ab7 ]
    
    As clearing REF_VERIFY mount option indicates there were some errors in a
    ref-verify process, a ref cache is not relevant anymore and should be
    freed.
    
    btrfs_free_ref_cache() requires REF_VERIFY option being set so call
    it just before clearing the mount option.
    
    Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
    
    Reported-by: syzbot+be14ed7728594dc8bd42@xxxxxxxxxxxxxxxxxxxxxxxxx
    Fixes: fd708b81d972 ("Btrfs: add a extent ref verify tool")
    CC: stable@xxxxxxxxxxxxxxx # 5.4+
    Closes: https://lore.kernel.org/lkml/000000000000e5a65c05ee832054@xxxxxxxxxx/
    Reported-by: syzbot+c563a3c79927971f950f@xxxxxxxxxxxxxxxxxxxxxxxxx
    Closes: https://lore.kernel.org/lkml/0000000000007fe09705fdc6086c@xxxxxxxxxx/
    Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
    Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
    Reviewed-by: David Sterba <dsterba@xxxxxxxx>
    Signed-off-by: David Sterba <dsterba@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index b26739d0e991b..7bb816a6d1e19 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -891,8 +891,10 @@ int btrfs_ref_tree_mod(struct btrfs_root *root, u64 bytenr, u64 num_bytes,
 out_unlock:
 	spin_unlock(&root->fs_info->ref_verify_lock);
 out:
-	if (ret)
+	if (ret) {
+		btrfs_free_ref_cache(fs_info);
 		btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
+	}
 	return ret;
 }
 
@@ -1021,8 +1023,8 @@ int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 		}
 	}
 	if (ret) {
-		btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
 		btrfs_free_ref_cache(fs_info);
+		btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
 	}
 	btrfs_free_path(path);
 	return ret;