From: Andreas Dilger <adilger@dilger.ca>
To: Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
yebin <yebin10@huawei.com>,
linux-block <linux-block@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH RFC 2/2] block: Do not discard buffers under a mounted filesystem
Date: Fri, 28 Aug 2020 02:21:29 -0600 [thread overview]
Message-ID: <F9505A56-F07B-4308-BE42-F75ED76B4E3C@dilger.ca> (raw)
In-Reply-To: <20200825121616.GA10294@infradead.org>
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On Aug 25, 2020, at 6:16 AM, Christoph Hellwig <hch@infradead.org> wrote:
>
> On Tue, Aug 25, 2020 at 02:05:54PM +0200, Jan Kara wrote:
>> Discarding blocks and buffers under a mounted filesystem is hardly
>> anything admin wants to do. Usually it will confuse the filesystem and
>> sometimes the loss of buffer_head state (including b_private field) can
>> even cause crashes like:
>
> Doesn't work if the file system uses multiple devices.
It's not _worse_ than the current situation of allowing the complete
destruction of the mounted filesystem. It doesn't fix the problem
for XFS with realtime devices, or ext4 with a separate journal device,
but it fixes the problem for a majority of users with a single device
filesystem.
While BLKFLSBUF causing a crash is annoying, BLKDISCARD/BLKSECDISCARD
under a mounted filesystem is definitely dangerous and wrong.
What about checking for O_EXCL on the device, indicating that it is
currently in use by some higher level?
Cheers, Andreas
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next prev parent reply other threads:[~2020-08-28 8:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 12:05 [PATCH RFC 0/2] Block and buffer invalidation under a filesystem Jan Kara
2020-08-25 12:05 ` [PATCH RFC 1/2] fs: Don't invalidate page buffers in block_write_full_page() Jan Kara
2020-08-25 12:05 ` [PATCH RFC 2/2] block: Do not discard buffers under a mounted filesystem Jan Kara
2020-08-25 12:16 ` Christoph Hellwig
2020-08-25 14:10 ` Theodore Y. Ts'o
2020-08-25 15:12 ` Jan Kara
2020-08-25 18:41 ` Matthew Wilcox
2020-08-25 18:49 ` Jan Kara
2020-08-25 14:50 ` Jan Kara
2020-08-27 7:16 ` Christoph Hellwig
2020-08-27 21:39 ` Al Viro
2020-08-28 0:07 ` Dave Chinner
2020-08-28 8:10 ` Jan Kara
2020-08-28 8:21 ` Andreas Dilger [this message]
2020-08-29 6:40 ` Christoph Hellwig
2020-08-31 7:48 ` Jan Kara
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