Re: [PATCH] loop: stop using vfs_iter_{read,write} for buffered I/O

[Ming Lei <ming.lei@redhat.com>]

On Wed, Apr 09, 2025 at 03:09:40PM +0200, Christoph Hellwig wrote:
> vfs_iter_{read,write} always perform direct I/O when the file has the
> O_DIRECT flag set, which breaks disabling direct I/O using the
> LOOP_SET_STATUS / LOOP_SET_STATUS64 ioctls.
> 
> This was recenly reported as a regression, but as far as I can tell
> was only uncovered by better checking for block sizes and has been
> around since the direct I/O support was added.
> 
> Fix this by using the existing aio code that calls the raw read/write
> iter methods instead.  Note that despite the comments there is no need
> for block drivers to ever call flush_dcache_page themselves, and the
> call is a left-over from prehistoric times.
> 
> Fixes: ab1cb278bc70 ("block: loop: introduce ioctl command of LOOP_SET_DIRECT_IO")
> Reported-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks fine,

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming