Re: [PATCH] loop: move vfs_fsync() out of loop_update_dio()

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

On Mon, Mar 17, 2025 at 04:52:16PM +0800, 胡焜 wrote:
> > drivers/block/loop.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> 
> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> > index 1ec7417c7f00..be7e20064427 100644
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -205,8 +205,6 @@ static bool lo_can_use_dio(struct loop_device *lo)
> > */
> >  static inline void loop_update_dio(struct loop_device *lo)
> >  {
> > - bool dio_in_use = lo->lo_flags & LO_FLAGS_DIRECT_IO;
> > -
> >   lockdep_assert_held(&lo->lo_mutex);
> >   WARN_ON_ONCE(lo->lo_state == Lo_bound &&
> >        lo->lo_queue->mq_freeze_depth == 0);
> > @@ -215,10 +213,6 @@ static inline void loop_update_dio(struct loop_device *lo)
> >   lo->lo_flags |= LO_FLAGS_DIRECT_IO;
> >   if ((lo->lo_flags & LO_FLAGS_DIRECT_IO) && !lo_can_use_dio(lo))
> >   lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
> > -
> > - /* flush dirty pages before starting to issue direct I/O */
> > - if ((lo->lo_flags & LO_FLAGS_DIRECT_IO) && !dio_in_use)
> > - vfs_fsync(lo->lo_backing_file, 0);
> >  }
> >  
> >  /**
> > @@ -621,6 +615,9 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
> >   if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
> >  goto out_err;
>  
> > + /* may work in dio, so flush page cache for avoiding race */
> > + vfs_fsync(file, 0);
> > +
> >   /* and ... switch */
> >   disk_force_media_change(lo->lo_disk);
> >   blk_mq_freeze_queue(lo->lo_queue);
> > @@ -1098,6 +1095,9 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
> >   if (error)
> >   goto out_unlock;
>  
> > + /* may work in dio, so flush page cache for avoiding race */
> > + vfs_fsync(file, 0);
> > +
> >   loop_update_dio(lo);
> >   loop_sysfs_init(lo);
> >  
> > --
> > 2.44.0
> 
> 
> Hello Ming,
> 
> I would like to double check that this fix doesn't seem to have been merged into the main thread, will this version still be merged into mainline kernel tree?

The V2 has been sent out after updating comment, please verify if it fixes your issue:

https://lore.kernel.org/linux-block/20250318010318.3861682-1-ming.lei@redhat.com/

If yes, feel free to provide one tested-by for moving on.


Thanks, 
Ming