Re: [PATCH v2 00/34] Open block devices as files

Hi!

On Mon 05-02-24 12:55:18, Christian Brauner wrote:

On Tue, Jan 23, 2024 at 02:26:17PM +0100, Christian Brauner wrote:

quoted

Hey Christoph,
Hey Jan,
Hey Jens,

This opens block devices as files. Instead of introducing a separate
indirection into bdev_open_by_*() vis struct bdev_handle we can just
make bdev_file_open_by_*() return a struct file. Opening and closing a
block device from setup_bdev_super() and in all other places just
becomes equivalent to opening and closing a file.

This has held up in xfstests and in blktests so far and it seems stable
and clean. The equivalence of opening and closing block devices to
regular files is a win in and of itself imho. Added to that is the
ability to do away with struct bdev_handle completely and make various
low-level helpers private to the block layer.

All places were we currently stash a struct bdev_handle we just stash a
file and use an accessor such as file_bdev() akin to I_BDEV() to get to
the block device.

It's now also possible to use file->f_mapping as a replacement for
bdev->bd_inode->i_mapping and file->f_inode or file->f_mapping->host as
an alternative to bdev->bd_inode allowing us to significantly reduce or
even fully remove bdev->bd_inode in follow-up patches.

In addition, we could get rid of sb->s_bdev and various other places
that stash the block device directly and instead stash the block device
file. Again, this is follow-up work.

Thanks!
Christian

Signed-off-by: Christian Brauner <brauner@kernel.org>
---

With all fixes applied I've moved this into vfs.super on vfs/vfs.git so
this gets some exposure in -next asap. Please let me know if you have
quarrels with that.

No quarrels really. I went through the patches and all of them look fine to
me to feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

I have just noticed that in "bdev: make struct bdev_handle private to the
block layer" in bdev_open() we are still leaking the handle in case of
error. This is however temporary (until the end of the series when we get
rid of handles altogether) so whatever.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR