block: Return the soft block size for compat BLKBSZGET

BLKBSZGET returns the block device's soft block size, while BLKSSZGET
returns its logical sector size. The compat BLKBSZGET_32 handler uses
bdev_logical_block_size(), so it returns the wrong value when these
sizes differ.

For example, on an x86_64 kernel a native query of a RAM or loop device
with 512-byte logical sectors returns the initial soft block size of
4096 bytes, but an i386 process gets 512 bytes. This makes 32-bit
blockdev --getbsz and the BSZ column of --report disagree with native
queries, even without a preceding BLKBSZSET.

Use block_size() as the native handler and the pre-regression compat
handler do, and correct the case comment to describe the soft size.

Fixes: 9b81648cb5e3 ("compat_ioctl: simplify up block/ioctl.c")
Cc: stable@vger.kernel.org
Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20261023153645.37546-1-dennylin0707@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions