loop: fix LO_FLAGS_PARTSCAN hang (e02898b4) · Commits · 戴 / test

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: ("block/loop: fix race between I/O and set_status") Reported-by:

Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org Signed-off-by:

Omar Sandoval <osandov@fb.com> Reviewed-by:

Ming Lei <tom.leiming@gmail.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

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;
		}

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