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Commit e02898b4 authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe
Browse files

loop: fix LO_FLAGS_PARTSCAN hang 



loop_reread_partitions() needs to do I/O, but we just froze the queue,
so we end up waiting forever. This can easily be reproduced with losetup
-P. Fix it by moving the reread to after we unfreeze the queue.

Fixes: ecdd0959 ("block/loop: fix race between I/O and set_status")
Reported-by: default avatarTejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 302ad8cc

drivers/block/loop.c

+8 −7
Original line number Diff line number Diff line
@@ -1142,13 +1142,6 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 
	     (info->lo_flags & LO_FLAGS_AUTOCLEAR))

		lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;



	if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&

	     !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {

		lo->lo_flags |= LO_FLAGS_PARTSCAN;

		lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;

		loop_reread_partitions(lo, lo->lo_device);

	}



	lo->lo_encrypt_key_size = info->lo_encrypt_key_size;

	lo->lo_init[0] = info->lo_init[0];

	lo->lo_init[1] = info->lo_init[1];
@@ -1163,6 +1156,14 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 


 exit:

	blk_mq_unfreeze_queue(lo->lo_queue);



	if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&

	     !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {

		lo->lo_flags |= LO_FLAGS_PARTSCAN;

		lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;

		loop_reread_partitions(lo, lo->lo_device);

	}



	return err;

}