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Commit a2505b79 authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe
Browse files

loop: Split setting of lo_state from loop_clr_fd 



Move setting of lo_state to Lo_rundown out into the callers. That will
allow us to unlock loop_ctl_mutex while the loop device is protected
from other changes by its special state.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a1316544

drivers/block/loop.c

+31 −21
Original line number Diff line number Diff line
@@ -975,7 +975,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, 
		loop_reread_partitions(lo, bdev);



	/* Grab the block_device to prevent its destruction after we

	 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).

	 * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev).

	 */

	bdgrab(bdev);

	return 0;
@@ -1025,31 +1025,15 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 
	return err;

}



static int loop_clr_fd(struct loop_device *lo)

static int __loop_clr_fd(struct loop_device *lo)

{

	struct file *filp = lo->lo_backing_file;

	gfp_t gfp = lo->old_gfp_mask;

	struct block_device *bdev = lo->lo_device;



	if (lo->lo_state != Lo_bound)

	if (WARN_ON_ONCE(lo->lo_state != Lo_rundown))

		return -ENXIO;



	/*

	 * If we've explicitly asked to tear down the loop device,

	 * and it has an elevated reference count, set it for auto-teardown when

	 * the last reference goes away. This stops $!~#$@ udev from

	 * preventing teardown because it decided that it needs to run blkid on

	 * the loopback device whenever they appear. xfstests is notorious for

	 * failing tests because blkid via udev races with a losetup

	 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d

	 * command to fail with EBUSY.

	 */

	if (atomic_read(&lo->lo_refcnt) > 1) {

		lo->lo_flags |= LO_FLAGS_AUTOCLEAR;

		mutex_unlock(&loop_ctl_mutex);

		return 0;

	}



	if (filp == NULL)

		return -EINVAL;
@@ -1057,7 +1041,6 @@ static int loop_clr_fd(struct loop_device *lo) 
	blk_mq_freeze_queue(lo->lo_queue);



	spin_lock_irq(&lo->lo_lock);

	lo->lo_state = Lo_rundown;

	lo->lo_backing_file = NULL;

	spin_unlock_irq(&lo->lo_lock);
@@ -1110,6 +1093,30 @@ static int loop_clr_fd(struct loop_device *lo) 
	return 0;

}



static int loop_clr_fd(struct loop_device *lo)

{

	if (lo->lo_state != Lo_bound)

		return -ENXIO;

	/*

	 * If we've explicitly asked to tear down the loop device,

	 * and it has an elevated reference count, set it for auto-teardown when

	 * the last reference goes away. This stops $!~#$@ udev from

	 * preventing teardown because it decided that it needs to run blkid on

	 * the loopback device whenever they appear. xfstests is notorious for

	 * failing tests because blkid via udev races with a losetup

	 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d

	 * command to fail with EBUSY.

	 */

	if (atomic_read(&lo->lo_refcnt) > 1) {

		lo->lo_flags |= LO_FLAGS_AUTOCLEAR;

		mutex_unlock(&loop_ctl_mutex);

		return 0;

	}

	lo->lo_state = Lo_rundown;



	return __loop_clr_fd(lo);

}



static int

loop_set_status(struct loop_device *lo, const struct loop_info64 *info)

{
@@ -1691,11 +1698,14 @@ static void lo_release(struct gendisk *disk, fmode_t mode) 
		goto out_unlock;



	if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {

		if (lo->lo_state != Lo_bound)

			goto out_unlock;

		lo->lo_state = Lo_rundown;

		/*

		 * In autoclear mode, stop the loop thread

		 * and remove configuration after last close.

		 */

		err = loop_clr_fd(lo);

		err = __loop_clr_fd(lo);

		if (!err)

			return;

	} else if (lo->lo_state == Lo_bound) {