linux/drivers/block
Damien Le Moal 49c3b9266a block: null_blk: Improve device creation with configfs
Currently, the directory name used to create a nullb device through
sysfs is not used as the device name, potentially causing headaches for
users if devices are already created through the modprobe operation
withe the nr_device module parameter not set to 0. E.g. a user can do
"mkdir /sys/kernel/config/nullb/nullb0" to create a nullb device even
though /dev/nullb0 was already created by modprobe. In this case, the
configfs nullb device will be named nullb1, causing confusion for the
user.

Simplify this by using the configfs directory name as the nullb device
name, always, unless another nullb device is already using the same
name. E.g. if modprobe created nullb0, then:

$ mkdir /sys/kernel/config/nullb/nullb0
mkdir: cannot create directory '/sys/kernel/config/nullb/nullb0': File
exists

will be reported to the user.

To implement this, the function null_find_dev_by_name() is added to
check for the existence of a nullb device with the name used for a new
configfs device directory. nullb_group_make_item() uses this new
function to check if the directory name can be used as the disk name.
Finally, null_add_dev() is modified to use the device config item name
as the disk name for a new nullb device created using configfs.
The naming of devices created though modprobe remains unchanged.

Of note is that it is possible for a user to create through configfs a
nullb device with the same name as an existing device. E.g.

$ mkdir /sys/kernel/config/nullb/null

will successfully create the nullb device named "null" but this block
device will however not appear under /dev/ since /dev/null already
exists.

Suggested-by: Joseph Bacik <josef@toxicpanda.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20220420005718.3780004-5-damien.lemoal@opensource.wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-04 05:24:58 -06:00
..
aoe aoe: Avoid flush_scheduled_work() usage 2022-05-01 06:41:41 -06:00
drbd drbd: Return true/false (not 1/0) from bool functions 2022-04-17 19:54:24 -06:00
mtip32xx for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
null_blk block: null_blk: Improve device creation with configfs 2022-05-04 05:24:58 -06:00
paride Char/Misc and other driver changes for 5.17-rc1 2022-01-14 16:02:28 +01:00
rnbd rnbd-srv: use bdev_discard_alignment 2022-05-03 10:38:50 -06:00
xen-blkback xen-blkback: use bdev_discard_alignment 2022-05-04 05:24:40 -06:00
zram block: add a disk_openers helper 2022-04-18 06:54:09 -06:00
amiflop.c block: remove the ->rq_disk field in struct request 2021-11-29 06:41:29 -07:00
ataflop.c block: remove the ->rq_disk field in struct request 2021-11-29 06:41:29 -07:00
brd.c brd: remove brd_devices_mutex mutex 2022-01-17 07:19:40 -07:00
floppy.c floppy: use memcpy_{to,from}_bvec 2022-03-04 12:29:21 -07:00
Kconfig block: remove the rsxx driver 2021-12-16 10:57:04 -07:00
loop.c loop: remove a spurious clear of discard_alignment 2022-05-03 10:38:50 -06:00
loop.h loop: remove lo_refcount and avoid lo_mutex in ->open / ->release 2022-04-18 06:54:09 -06:00
Makefile block: remove the rsxx driver 2021-12-16 10:57:04 -07:00
n64cart.c n64cart: convert bi_disk to bi_bdev->bd_disk fix build 2022-03-21 06:34:45 -06:00
nbd.c nbd: don't set the discard_alignment queue limit 2022-05-03 10:38:50 -06:00
pktcdvd.c pktcdvd: stop using bio_reset 2022-04-17 19:30:47 -06:00
ps3disk.c ps3disk: add error handling support for add_disk() 2021-10-30 11:03:37 -06:00
ps3vram.c block: remove GENHD_FL_EXT_DEVT 2021-11-29 06:38:35 -07:00
rbd_types.h libceph, rbd: replace zero-length array with flexible-array 2020-06-01 13:22:53 +02:00
rbd.c block: remove QUEUE_FLAG_DISCARD 2022-04-17 19:49:59 -06:00
sunvdc.c block: remove genhd.h 2022-02-02 07:49:59 -07:00
swim_asm.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
swim.c block: remove GENHD_FL_EXT_DEVT 2021-11-29 06:38:35 -07:00
swim3.c block: remove GENHD_FL_EXT_DEVT 2021-11-29 06:38:35 -07:00
sx8.c block: remove the gendisk argument to blk_execute_rq 2021-11-29 06:41:29 -07:00
virtio_blk.c virtio_blk: fix the discard_granularity and discard_alignment queue limits 2022-05-03 10:38:50 -06:00
xen-blkfront.c block: decouple REQ_OP_SECURE_ERASE from REQ_OP_DISCARD 2022-04-17 19:49:59 -06:00
z2ram.c block: remove GENHD_FL_EXT_DEVT 2021-11-29 06:38:35 -07:00