Re: [PATCH RFC v2 01/18] xfs: fix the error unwind in xfs_open_devices()

[Christoph Hellwig]

On Tue, Jun 16, 2026 at 04:08:17PM +0200, Christian Brauner wrote:
> Since the rt and log block devices are closed in xfs_free_buftarg() the
> buftarg owns the device file. The error unwind does not respect that:
> when the log buftarg allocation fails, out_free_rtdev_targ frees the rt
> buftarg - releasing rtdev_file - and then falls through to
> out_close_rtdev and releases it a second time.
> 
> The unwind also leaves mp->m_rtdev_targp and mp->m_ddev_targp pointing
> to the freed buftargs. The failed mount continues into
> deactivate_locked_super() -> xfs_kill_sb() -> xfs_mount_free(), which
> frees them again.
> 
> Clear the buftarg pointers once the unwind freed them and clear
> rtdev_file once the rt buftarg owns it, so nothing is released twice.
> 
> Reachable when a buftarg allocation fails after the data buftarg was
> set up: an I/O error in sync_blockdev() or an allocation failure in
> xfs_init_buftarg() while mounting with external rt and log devices.

Looks good:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>

I actually have a major rework of this area pending, but it probably
won't land for 7.2, so we might as well get this local fix in ASAP.