On Mon, Aug 19, 2019 at 11:06 AM Martijn Coenen <maco@xxxxxxxxxxx> wrote:
> One idea to fix is to call blk_queue_logical_block_size() as part of
> LOOP_SET_FD, to match the block size of the backing fs in case the
> backing file is opened with O_DIRECT; you could argue that if the
> backing file is opened with O_DIRECT, this is what the user wanted
> anyway. This would allow us to get rid of the latter two ioctl's and
> already save quite some time.
Basically:
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ab7ca5989097a..ad3db72fbd729 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -994,6 +994,12 @@ static int loop_set_fd(struct loop_device *lo,
fmode_t mode,
if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
blk_queue_write_cache(lo->lo_queue, true, false);
+ if(io_is_direct(lo->lo_backing_file) && inode->i_sb->s_bdev) {
+ /* In case of direct I/O, match underlying block size */
+ blk_queue_logical_block_size(lo->lo_queue,
+ bdev_logical_block_size(inode->i_sb->s_bdev));
+ }
+
loop_update_rotational(lo);
loop_update_dio(lo);
>
> Thanks,
> Martijn
>
> >
> > Something like the following patch:
> >
> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> > index a7461f482467..8791f9242583 100644
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -1015,6 +1015,9 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
> > */
> > bdgrab(bdev);
> > mutex_unlock(&loop_ctl_mutex);
> > +
> > + percpu_ref_switch_to_percpu(&lo->lo_queue->q_usage_counter);
> > +
> > if (partscan)
> > loop_reread_partitions(lo, bdev);
> > if (claimed_bdev)
> > @@ -1171,6 +1174,8 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
> > lo->lo_state = Lo_unbound;
> > mutex_unlock(&loop_ctl_mutex);
> >
> > + percpu_ref_switch_to_atomic(&lo->lo_queue->q_usage_counter, NULL);
> > +
> > /*
> > * Need not hold loop_ctl_mutex to fput backing file.
> > * Calling fput holding loop_ctl_mutex triggers a circular
> > @@ -2003,6 +2008,12 @@ static int loop_add(struct loop_device **l, int i)
> > }
> > lo->lo_queue->queuedata = lo;
> >
> > + /*
> > + * cheat block layer for not switching to q_usage_counter's
> > + * percpu mode before loop becomes Lo_bound
> > + */
> > + blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, lo->lo_queue);
> > +
> > blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
> >
> > /*
> >
> >
> > thanks,
> > Ming
