From: Christoph Hellwig <hch@infradead.org>
To: Kent Overstreet <kent.overstreet@linux.dev>
Cc: linux-bcachefs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 05/20] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset
Date: Mon, 24 Jul 2023 10:34:20 -0700 [thread overview]
Message-ID: <ZL62HKrAJapXfcaR@infradead.org> (raw)
In-Reply-To: <20230712211115.2174650-6-kent.overstreet@linux.dev>
On Wed, Jul 12, 2023 at 05:11:00PM -0400, Kent Overstreet wrote:
> bio_iov_iter_get_pages() trims the IO based on the block size of the
> block device the IO will be issued to.
>
> However, bcachefs is a multi device filesystem; when we're creating the
> bio we don't yet know which block device the bio will be submitted to -
> we have to handle the alignment checks elsewhere.
So, we've been trying really hard to always make sure to pass a bdev
to anything that allocates a bio, mostly due due the fact that we
actually derive information like the blk-cgroup associations from it.
The whole blk-cgroup stuff is actually a problem for non-trivial
multi-device setups. XFS gets away fine because each file just
sits on either the main or RT device and no user I/O goes to the
log device, and btrfs papers over it in a weird way by always
associating with the last added device, which is in many ways gross
and wrong, but at least satisfies the assumptions made in blk-cgroup.
How do you plan to deal with this? Because I really don't want folks
just to go ahead and ignore the issues, we need to actually sort this
out.
next prev parent reply other threads:[~2023-07-24 17:34 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 21:10 [PATCH 00/20] bcachefs prereqs patch series Kent Overstreet
2023-07-12 21:10 ` [PATCH 01/20] sched: Add task_struct->faults_disabled_mapping Kent Overstreet
2023-07-12 21:10 ` [PATCH 02/20] fs: factor out d_mark_tmpfile() Kent Overstreet
2023-07-12 21:10 ` [PATCH 03/20] iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic() Kent Overstreet
2023-07-12 21:10 ` [PATCH 04/20] block: Add some exports for bcachefs Kent Overstreet
2023-07-24 17:31 ` Christoph Hellwig
2023-07-25 3:00 ` Kent Overstreet
2023-07-26 13:20 ` Christoph Hellwig
2023-08-01 18:59 ` Kent Overstreet
2023-07-25 2:59 ` Matthew Wilcox
2023-07-12 21:11 ` [PATCH 05/20] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset Kent Overstreet
2023-07-24 17:34 ` Christoph Hellwig [this message]
2023-07-25 2:43 ` Kent Overstreet
2023-07-26 13:23 ` Christoph Hellwig
2023-08-01 19:04 ` Kent Overstreet
2023-08-02 11:47 ` Christoph Hellwig
2023-08-02 16:44 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 06/20] block: Bring back zero_fill_bio_iter Kent Overstreet
2023-07-24 17:35 ` Christoph Hellwig
2023-07-25 2:45 ` Kent Overstreet
2023-07-26 13:21 ` Christoph Hellwig
2023-08-01 19:05 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 07/20] block: Don't block on s_umount from __invalidate_super() Kent Overstreet
2023-07-12 21:11 ` [PATCH 08/20] stacktrace: Export stack_trace_save_tsk Kent Overstreet
2023-07-12 21:11 ` [PATCH 09/20] lib/string_helpers: string_get_size() now returns characters wrote Kent Overstreet
2023-07-12 21:11 ` [PATCH 10/20] lib: Export errname Kent Overstreet
2023-07-13 7:10 ` Eric Biggers
2023-07-12 21:11 ` [PATCH 11/20] locking/osq: Export osq_(lock|unlock) Kent Overstreet
2023-08-02 20:16 ` Waiman Long
2023-08-02 20:44 ` Kent Overstreet
2023-08-02 21:09 ` Waiman Long
2023-08-02 21:42 ` Kent Overstreet
2023-10-10 8:09 ` [NAK] " Ingo Molnar
2023-10-18 21:04 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 12/20] bcache: move closures to lib/ Kent Overstreet
2023-07-13 3:21 ` Randy Dunlap
2023-07-13 3:52 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 13/20] MAINTAINERS: Add entry for closures Kent Overstreet
2023-07-12 21:11 ` [PATCH 14/20] closures: closure_wait_event() Kent Overstreet
2023-07-12 21:11 ` [PATCH 15/20] closures: closure_nr_remaining() Kent Overstreet
2023-07-12 21:11 ` [PATCH 16/20] closures: Add a missing include Kent Overstreet
2023-07-12 21:11 ` [PATCH 17/20] MAINTAINERS: Add entry for generic-radix-tree Kent Overstreet
2023-07-12 21:11 ` [PATCH 18/20] lib/generic-radix-tree.c: Don't overflow in peek() Kent Overstreet
2023-07-12 21:11 ` [PATCH 19/20] lib/generic-radix-tree.c: Add a missing include Kent Overstreet
2023-07-25 3:04 ` Matthew Wilcox
2023-07-25 3:36 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 20/20] lib/generic-radix-tree.c: Add peek_prev() Kent Overstreet
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZL62HKrAJapXfcaR@infradead.org \
--to=hch@infradead.org \
--cc=axboe@kernel.dk \
--cc=kent.overstreet@linux.dev \
--cc=linux-bcachefs@vger.kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.