Commit 9f65c489 authored by Matteo Croce's avatar Matteo Croce Committed by Jens Axboe
Browse files

loop: raise media_change event 



Make the loop device raise a DISK_MEDIA_CHANGE event on attach or detach.

	# udevadm monitor -up |grep -e DISK_MEDIA_CHANGE -e DEVNAME &

	# losetup -f zero
	[    7.454235] loop0: detected capacity change from 0 to 16384
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop0
	DEVNAME=/dev/loop0
	DEVNAME=/dev/loop0

	# losetup -f zero
	[   10.205245] loop1: detected capacity change from 0 to 16384
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop1
	DEVNAME=/dev/loop1
	DEVNAME=/dev/loop1

	# losetup -f zero2
	[   13.532368] loop2: detected capacity change from 0 to 40960
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop2
	DEVNAME=/dev/loop2

	# losetup -D
	DEVNAME=/dev/loop1
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop1
	DEVNAME=/dev/loop2
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop2
	DEVNAME=/dev/loop0
	DISK_MEDIA_CHANGE=1
	DEVNAME=/dev/loop0

Signed-off-by: default avatarMatteo Croce <mcroce@microsoft.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarLuca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-7-mcroce@linux.microsoft.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e6138dc1

drivers/block/loop.c

+5 −0
Original line number Diff line number Diff line
@@ -774,6 +774,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 
		goto out_err;



	/* and ... switch */

	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);

	blk_mq_freeze_queue(lo->lo_queue);

	mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);

	lo->lo_backing_file = file;
@@ -1257,6 +1258,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, 
		goto out_unlock;

	}



	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);

	set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);



	INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
@@ -1410,6 +1412,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) 


	partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;

	lo_number = lo->lo_number;

	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);

out_unlock:

	mutex_unlock(&lo->lo_mutex);

	if (partscan) {
@@ -2386,6 +2389,8 @@ static int loop_add(int i) 
	disk->fops		= &lo_fops;

	disk->private_data	= lo;

	disk->queue		= lo->lo_queue;

	disk->events		= DISK_EVENT_MEDIA_CHANGE;

	disk->event_flags	= DISK_EVENT_FLAG_UEVENT;

	sprintf(disk->disk_name, "loop%d", i);

	add_disk(disk);

	mutex_unlock(&loop_ctl_mutex);