Without calling loop_config_discard() the discard flag and parameters aren't set/updated for the loop device and worst-case they could indicate discard support when it isn't the case (ex: if the LOOP_SET_STATUS ioctl was used with a different file prior to LOOP_CONFIGURE).

Cc: stable@vger.kernel.org # 5.8.x- Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl") Signed-off-by: Kristian Klausen kristian@klausen.dk --- v1 of the patch was tested like so (without the patch): losetup 2.37<= uses LOOP_CONFIGURE instead of LOOP_SET_STATUS64[1]

# fallocate -l100M disk.img # rmmod loop # losetup --version losetup from util-linux 2.36.2 # losetup --find --show disk.img /dev/loop0 # grep '' /sys/devices/virtual/block/loop0/queue/*discard* /sys/devices/virtual/block/loop0/queue/discard_granularity:4096 /sys/devices/virtual/block/loop0/queue/discard_max_bytes:4294966784 /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:4294966784 /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0 /sys/devices/virtual/block/loop0/queue/max_discard_segments:1 # losetup -d /dev/loop0 # [update util-linux] # losetup --version losetup from util-linux 2.37 # rmmod loop # losetup --find --show disk.img /dev/loop0 # grep '' /sys/devices/virtual/block/loop0/queue/*discard* /sys/devices/virtual/block/loop0/queue/discard_granularity:0 /sys/devices/virtual/block/loop0/queue/discard_max_bytes:0 /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:0 /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0 /sys/devices/virtual/block/loop0/queue/max_discard_segments:1

With the patch applied:

# losetup --version losetup from util-linux 2.37 # rmmod loop # losetup --find --show disk.img /dev/loop0 # grep '' /sys/devices/virtual/block/loop0/queue/*discard* /sys/devices/virtual/block/loop0/queue/discard_granularity:4096 /sys/devices/virtual/block/loop0/queue/discard_max_bytes:4294966784 /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:4294966784 /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0 /sys/devices/virtual/block/loop0/queue/max_discard_segments:1

[1] https://github.com/karelzak/util-linux/pull/1152

v2: Add commit message Move loop_config_discard() before loop_update_rotational()

drivers/block/loop.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 76e12f3482a9..8271df125153 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1154,6 +1154,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, blk_queue_physical_block_size(lo->lo_queue, bsize); blk_queue_io_min(lo->lo_queue, bsize);

+ loop_config_discard(lo); loop_update_rotational(lo); loop_update_dio(lo); loop_sysfs_init(lo);

base-commit: 70585216fe7730d9fb5453d3e2804e149d0fe201