Re: don't use ->bd_inode to access the block device size

Kees Cook
2021-10-13T09:30:03Z

On Wed, Oct 13, 2021 at 07:10:13AM +0200, Christoph Hellwig wrote:
> I wondered about adding a helper for looking at the size in byte units
> to avoid the SECTOR_SHIFT shifts in various places. But given that
> I could not come up with a good name and block devices fundamentally
> work in sector size granularity I decided against that.

Without something like bdev_nr_bytes(), this series has 13 of 29 patches
actually _adding_ an open-coded calculation:

[PATCH 05/29] mtd/block2mtd: use bdev_nr_sectors instead of open coding it
[PATCH 06/29] nvmet: use bdev_nr_sectors instead of open coding it
[PATCH 07/29] target/iblock: use bdev_nr_sectors instead of open coding it
[PATCH 08/29] fs: use bdev_nr_sectors instead of open coding it in blkdev_max_block
[PATCH 11/29] btrfs: use bdev_nr_sectors instead of open coding it
[PATCH 16/29] jfs: use bdev_nr_sectors instead of open coding it
[PATCH 17/29] nfs/blocklayout: use bdev_nr_sectors instead of open coding it
[PATCH 18/29] nilfs2: use bdev_nr_sectors instead of open coding it
[PATCH 19/29] ntfs3: use bdev_nr_sectors instead of open coding it
[PATCH 20/29] pstore/blk: use bdev_nr_sectors instead of open coding it
[PATCH 21/29] reiserfs: use bdev_nr_sectors instead of open coding it
[PATCH 22/29] squashfs: use bdev_nr_sectors instead of open coding it
[PATCH 23/29] block: use bdev_nr_sectors instead of open coding it in blkdev_fallocate

I think it's well worth having that helper (or at least leaving these
alone). Otherwise, this is a lot of churn without a clear net benefit,
IMO.

The others look good to me, though!

-Kees

>
> Diffstat:
> block/fops.c | 2 +-
> drivers/block/drbd/drbd_int.h | 3 +--
> drivers/md/bcache/super.c | 2 +-
> drivers/md/bcache/util.h | 4 ----
> drivers/md/bcache/writeback.c | 2 +-
> drivers/md/dm-bufio.c | 2 +-
> drivers/md/dm-cache-metadata.c | 2 +-
> drivers/md/dm-cache-target.c | 2 +-
> drivers/md/dm-clone-target.c | 2 +-
> drivers/md/dm-dust.c | 5 ++---
> drivers/md/dm-ebs-target.c | 2 +-
> drivers/md/dm-era-target.c | 2 +-
> drivers/md/dm-exception-store.h | 2 +-
> drivers/md/dm-flakey.c | 3 +--
> drivers/md/dm-integrity.c | 6 +++---
> drivers/md/dm-linear.c | 3 +--
> drivers/md/dm-log-writes.c | 4 ++--
> drivers/md/dm-log.c | 2 +-
> drivers/md/dm-mpath.c | 2 +-
> drivers/md/dm-raid.c | 6 +++---
> drivers/md/dm-switch.c | 2 +-
> drivers/md/dm-table.c | 3 +--
> drivers/md/dm-thin-metadata.c | 2 +-
> drivers/md/dm-thin.c | 2 +-
> drivers/md/dm-verity-target.c | 3 +--
> drivers/md/dm-writecache.c | 2 +-
> drivers/md/dm-zoned-target.c | 2 +-
> drivers/md/md.c | 26 +++++++++++---------------
> drivers/mtd/devices/block2mtd.c | 5 +++--
> drivers/nvme/target/io-cmd-bdev.c | 4 ++--
> drivers/target/target_core_iblock.c | 5 +++--
> fs/affs/super.c | 2 +-
> fs/btrfs/dev-replace.c | 2 +-
> fs/btrfs/disk-io.c | 3 ++-
> fs/btrfs/ioctl.c | 4 ++--
> fs/btrfs/volumes.c | 7 ++++---
> fs/buffer.c | 4 ++--
> fs/cramfs/inode.c | 2 +-
> fs/ext4/super.c | 2 +-
> fs/fat/inode.c | 5 +----
> fs/hfs/mdb.c | 2 +-
> fs/hfsplus/wrapper.c | 2 +-
> fs/jfs/resize.c | 5 ++---
> fs/jfs/super.c | 5 ++---
> fs/nfs/blocklayout/dev.c | 4 ++--
> fs/nilfs2/ioctl.c | 2 +-
> fs/nilfs2/super.c | 2 +-
> fs/nilfs2/the_nilfs.c | 3 ++-
> fs/ntfs/super.c | 8 +++-----
> fs/ntfs3/super.c | 3 +--
> fs/pstore/blk.c | 4 ++--
> fs/reiserfs/super.c | 7 ++-----
> fs/squashfs/super.c | 5 +++--
> fs/udf/lowlevel.c | 5 ++---
> fs/udf/super.c | 9 +++------
> include/linux/genhd.h | 6 ++++++
> 56 files changed, 100 insertions(+), 117 deletions(-)

--
Kees Cook