Re: [f2fs-dev] [PATCH 1/3] btrfs: call btrfs_close_devices from ->kill_sb

[Josef Bacik <josef@toxicpanda.com>]

On Sat, Dec 16, 2023 at 05:12:21AM +0100, Christoph Hellwig wrote:
> On Fri, Dec 15, 2023 at 04:45:50PM -0500, Josef Bacik wrote:
> > I ran it through, you broke a test that isn't upstream yet to test the old mount
> > api double mount thing that I have a test for
> > 
> > https://github.com/btrfs/fstests/commit/2796723e77adb0f9da1059acf13fc402467f7ac4
> > 
> > In this case we end up leaking a reference on the fs_devices.  If you add this
> > fixup to "btrfs: call btrfs_close_devices from ->kill_sb" it fixes that failure.
> > I'm re-running with that fixup applied, but I assume the rest is fine.  Thanks,
> 
> Is "this fixup" referring to a patch that was supposed to be attached
> but is't? :)

Sorry, vacation brain, here you go.

Josef

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f93fe2e5e378..2dfa2274b193 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1950,10 +1950,20 @@ static int btrfs_get_tree_super(struct fs_context *fc)
  */
 static struct vfsmount *btrfs_reconfigure_for_mount(struct fs_context *fc)
 {
+	struct btrfs_fs_info *fs_info = fc->s_fs_info;
 	struct vfsmount *mnt;
 	int ret;
 	const bool ro2rw = !(fc->sb_flags & SB_RDONLY);
 
+	/*
+	 * We got a reference to our fs_devices, so we need to close it here to
+	 * make sure we don't leak our reference on the fs_devices.
+	 */
+	if (fs_info->fs_devices) {
+		btrfs_close_devices(fs_info->fs_devices);
+		fs_info->fs_devices = NULL;
+	}
+
 	/*
 	 * We got an EBUSY because our SB_RDONLY flag didn't match the existing
 	 * super block, so invert our setting here and retry the mount so we