loop: set GENHD_FL_NO_PART_SCAN after blkdev_reread_part() (758a58d0) · Commits · 戴 / test

Commit ("loop: Fix deadlock when calling blkdev_reread_part()") moves blkdev_reread_part() out of the loop_ctl_mutex. However, GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result, __blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and will not rescan the loop device to delete all partitions. Below are steps to reproduce the issue: step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100 step2 # losetup -P /dev/loop0 tmp.raw step3 # parted /dev/loop0 mklabel gpt step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1 step5 # losetup -d /dev/loop0 Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and there is below kernel warning message: [ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22) This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part(). Fixes: ("loop: Fix deadlock when calling blkdev_reread_part()") Signed-off-by:

Dongli Zhang <dongli.zhang@oracle.com> Reviewed-by:

Jan Kara <jack@suse.cz> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

drivers/block/loop.c

+17 −4

Original line number	Diff line number	Diff line
		@@ -1089,16 +1089,12 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
		}
		mapping_set_gfp_mask(filp->f_mapping, gfp);
		lo->lo_state = Lo_unbound;
		/* This is safe: open() is still holding a reference. */
		module_put(THIS_MODULE);
		blk_mq_unfreeze_queue(lo->lo_queue);

		partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
		lo_number = lo->lo_number;
		lo->lo_flags = 0;
		if (!part_shift)
		lo->lo_disk->flags \|= GENHD_FL_NO_PART_SCAN;
		loop_unprepare_queue(lo);
		out_unlock:
		mutex_unlock(&loop_ctl_mutex);
		@@ -1121,6 +1117,23 @@ out_unlock:
		/* Device is gone, no point in returning error */
		err = 0;
		}

		/*
		* lo->lo_state is set to Lo_unbound here after above partscan has
		* finished.
		*
		* There cannot be anybody else entering __loop_clr_fd() as
		* lo->lo_backing_file is already cleared and Lo_rundown state
		* protects us from all the other places trying to change the 'lo'
		* device.
		*/
		mutex_lock(&loop_ctl_mutex);
		lo->lo_flags = 0;
		if (!part_shift)
		lo->lo_disk->flags \|= GENHD_FL_NO_PART_SCAN;
		lo->lo_state = Lo_unbound;
		mutex_unlock(&loop_ctl_mutex);

		/*
		* Need not hold loop_ctl_mutex to fput backing file.
		* Calling fput holding loop_ctl_mutex triggers a circular

Admin message