From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org
Subject: Re: [PATCH] Revert "block: Do not discard buffers under a mounted filesystem"
Date: Tue, 16 Feb 2021 09:49:41 -0800 [thread overview]
Message-ID: <20210216174941.GA2708768@dhcp-10-100-145-180.wdc.com> (raw)
In-Reply-To: <20210216163606.GA4063489@infradead.org>
On Tue, Feb 16, 2021 at 04:36:06PM +0000, Christoph Hellwig wrote:
> On Tue, Feb 16, 2021 at 02:38:49PM +0100, Jan Kara wrote:
> > Apparently there are several userspace programs that depend on being
> > able to call BLKDISCARD ioctl without the ability to grab bdev
> > exclusively - namely FUSE filesystems have the device open without
> > O_EXCL (the kernel has the bdev open with O_EXCL) so the commit breaks
> > fstrim(8) for such filesystems. Also LVM when shrinking LV opens PV and
> > discards ranges released from LV but that PV may be already open
> > exclusively by someone else (see bugzilla link below for more details).
> >
> > This reverts commit 384d87ef2c954fc58e6c5fd8253e4a1984f5fe02.
>
> I think that is a bad idea. We fixed the problem for a reason.
> I think the right fix is to just do nothing if the device hasn't been
> opened with O_EXCL and can't be reopened with it, just don't do anything
> but also don't return an error. After all discard and thus
> BLKDISCARD is purely advisory.
A discard is advisory, but BLKZEROOUT is not, so something different
should happen there. We were also planning to send a patch using this
same pattern for Zone Reset to fix stale page cache issues after the
reset, but we'll wait to see how this settles before sending that.
next prev parent reply other threads:[~2021-02-16 17:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-16 13:38 [PATCH] Revert "block: Do not discard buffers under a mounted filesystem" Jan Kara
2021-02-16 16:36 ` Christoph Hellwig
2021-02-16 17:16 ` Jan Kara
2021-02-18 11:17 ` Jan Kara
2021-02-16 17:49 ` Keith Busch [this message]
2021-02-16 23:05 ` Damien Le Moal
2021-02-18 14:07 ` Jan Kara
2021-02-18 22:35 ` Damien Le Moal
2021-02-19 10:27 ` Jan Kara
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