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Commit d57f3374 authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe
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loop: Move special partition reread handling in loop_clr_fd() 



The call of __blkdev_reread_part() from loop_reread_partition() happens
only when we need to invalidate partitions from loop_release(). Thus
move a detection for this into loop_clr_fd() and simplify
loop_reread_partition().

This makes loop_reread_partition() safe to use without loop_ctl_mutex
because we use only lo->lo_number and lo->lo_file_name in case of error
for reporting purposes (thus possibly reporting outdate information is
not a big deal) and we are safe from 'lo' going away under us by
elevated lo->lo_refcnt.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c3710770

drivers/block/loop.c

+19 −14
Original line number Diff line number Diff line
@@ -630,17 +630,6 @@ static void loop_reread_partitions(struct loop_device *lo, 
{

	int rc;



	/*

	 * bd_mutex has been held already in release path, so don't

	 * acquire it if this function is called in such case.

	 *

	 * If the reread partition isn't from release path, lo_refcnt

	 * must be at least one and it can only become zero when the

	 * current holder is released.

	 */

	if (!atomic_read(&lo->lo_refcnt))

		rc = __blkdev_reread_part(bdev);

	else

	rc = blkdev_reread_part(bdev);

	if (rc)

		pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
@@ -1095,8 +1084,24 @@ static int __loop_clr_fd(struct loop_device *lo) 
	module_put(THIS_MODULE);

	blk_mq_unfreeze_queue(lo->lo_queue);



	if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)

		loop_reread_partitions(lo, bdev);

	if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) {

		/*

		 * bd_mutex has been held already in release path, so don't

		 * acquire it if this function is called in such case.

		 *

		 * If the reread partition isn't from release path, lo_refcnt

		 * must be at least one and it can only become zero when the

		 * current holder is released.

		 */

		if (!atomic_read(&lo->lo_refcnt))

			err = __blkdev_reread_part(bdev);

		else

			err = blkdev_reread_part(bdev);

		pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",

			__func__, lo->lo_number, err);

		/* Device is gone, no point in returning error */

		err = 0;

	}

	lo->lo_flags = 0;

	if (!part_shift)

		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;