From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Christoph Hellwig <hch@infradead.org>, Qu Wenruo <wqu@suse.com>,
linux-btrfs@vger.kernel.org, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH v3 3/4] iomap: reject NOWAIT and BOUNCE direct IOs
Date: Mon, 15 Jun 2026 22:19:46 -0700 [thread overview]
Message-ID: <ajDc8nFYyiQ66TOR@infradead.org> (raw)
In-Reply-To: <8a0e1881-fe73-4912-95f9-8eac998840d5@gmx.com>
On Tue, Jun 16, 2026 at 10:30:27AM +0930, Qu Wenruo wrote:
> After scanning the code for related memory allocation, there are some other
> locations doing memory allocation, including but not limited to:
>
> - iomap_dio_alloc_bio()
> This one is a little tricky, if we pass GFP_NOWAIT, we can break the
> old assumption that the function will always return a bio.
>
> - fscrypt_set_bio_crypt_ctx()
> This one is fine so far, as neither XFS nor btrfs support fscrypt yet.
>
> And any memory allocation failure in NOWAIT mode should return -EAGAIN, not
> -ENOMEM so that the caller can retry in blocking mode as a fallback.
>
> To me, considering NOWAIT itself is only an optimistic flag, and caller
> should always have a blocking mode as fallback, I'd prefer to reject NOWAIT
> + BOUNCE direct writes completely inside btrfs for now.
If you want to do that in btrfs please do it there.
> And leave all the missing NOWAIT handling in iomap in a dedicated series.
This might be worth looking into.
next prev parent reply other threads:[~2026-06-16 5:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 9:51 [PATCH v3 0/4] btrfs: use IOMAP_DIO_BOUNCE flag instead of falling back to buffered IO Qu Wenruo
2026-06-12 9:51 ` [PATCH v3 1/4] block: revert the iov_iter after a short copy in bio_iov_iter_bounce_write() Qu Wenruo
2026-06-15 15:03 ` Christoph Hellwig
2026-06-12 9:51 ` [PATCH v3 2/4] block: respect iov_iter::nofault flag " Qu Wenruo
2026-06-15 15:05 ` Christoph Hellwig
2026-06-12 9:51 ` [PATCH v3 3/4] iomap: reject NOWAIT and BOUNCE direct IOs Qu Wenruo
2026-06-15 15:05 ` Christoph Hellwig
2026-06-15 22:43 ` Qu Wenruo
2026-06-16 1:00 ` Qu Wenruo
2026-06-16 5:19 ` Christoph Hellwig [this message]
2026-06-16 5:18 ` Christoph Hellwig
2026-06-12 9:51 ` [PATCH v3 4/4] btrfs: use IOMAP_DIO_BOUNCE flag instead of falling back to buffered IO Qu Wenruo
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=ajDc8nFYyiQ66TOR@infradead.org \
--to=hch@infradead.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=quwenruo.btrfs@gmx.com \
--cc=wqu@suse.com \
/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.