From: Christoph Hellwig <hch@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] Revert "block: Do not discard buffers under a mounted filesystem"
Date: Tue, 16 Feb 2021 16:36:06 +0000 [thread overview]
Message-ID: <20210216163606.GA4063489@infradead.org> (raw)
In-Reply-To: <20210216133849.8244-1-jack@suse.cz>
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.
next prev parent reply other threads:[~2021-02-16 16:38 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 [this message]
2021-02-16 17:16 ` Jan Kara
2021-02-18 11:17 ` Jan Kara
2021-02-16 17:49 ` Keith Busch
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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