From: Jan Kara <jack@suse.cz>
To: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>, Maxim Levitsky <mlevitsk@redhat.com>,
linux-fsdevel@vger.kernel.org,
"Darrick J. Wong" <darrick.wong@oracle.com>
Subject: Re: [PATCH] bdev: Do not return EBUSY if bdev discard races with write
Date: Wed, 27 Jan 2021 10:12:37 +0100 [thread overview]
Message-ID: <20210127091237.GA3108@quack2.suse.cz> (raw)
In-Reply-To: <29be3d51-43b4-b4eb-66e0-669c517ed830@kernel.dk>
On Tue 26-01-21 10:22:56, Jens Axboe wrote:
> On 1/26/21 3:02 AM, Jan Kara wrote:
> > On Thu 07-01-21 16:40:34, Jan Kara wrote:
> >> blkdev_fallocate() tries to detect whether a discard raced with an
> >> overlapping write by calling invalidate_inode_pages2_range(). However
> >> this check can give both false negatives (when writing using direct IO
> >> or when writeback already writes out the written pagecache range) and
> >> false positives (when write is not actually overlapping but ends in the
> >> same page when blocksize < pagesize). This actually causes issues for
> >> qemu which is getting confused by EBUSY errors.
> >>
> >> Fix the problem by removing this conflicting write detection since it is
> >> inherently racy and thus of little use anyway.
> >>
> >> Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
> >> CC: "Darrick J. Wong" <darrick.wong@oracle.com>
> >> Link: https://lore.kernel.org/qemu-devel/20201111153913.41840-1-mlevitsk@redhat.com
> >> Signed-off-by: Jan Kara <jack@suse.cz>
> >
> > Jens, can you please pick up this patch? Thanks!
>
> Picked it up for 5.12, hope that works. It looks simple enough but not
> really meeting criteria for 5.11 at this point.
Sure, 5.12 is fine. We've been living with the current behavior for quite
some time and not many people complained...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
prev parent reply other threads:[~2021-01-27 9:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 15:40 [PATCH] bdev: Do not return EBUSY if bdev discard races with write Jan Kara
2021-01-07 15:48 ` Maxim Levitsky
2021-01-07 15:52 ` Maxim Levitsky
2021-01-07 19:40 ` Darrick J. Wong
2021-01-09 10:42 ` Christoph Hellwig
2021-01-26 10:02 ` Jan Kara
2021-01-26 17:22 ` Jens Axboe
2021-01-27 9:12 ` Jan Kara [this message]
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