From: Christoph Hellwig <hch@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org, yebin <yebin10@huawei.com>,
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: Thu, 27 Aug 2020 08:16:03 +0100 [thread overview]
Message-ID: <20200827071603.GA25305@infradead.org> (raw)
In-Reply-To: <20200825145056.GC32298@quack2.suse.cz>
On Tue, Aug 25, 2020 at 04:50:56PM +0200, Jan Kara wrote:
> Do you mean that address_space filesystem uses to access its metadata on
> /dev/sda will be different from the address_space you will see when reading
> say /dev/sda? Thus these will be completely separate (and incoherent)
> caches?
Yes.
> Although this would be simple it will break userspace I'm afraid.
> There are situations where tools read e.g. superblock of a mounted
> filesystem from the block device and rely on the data to be reasonably
> recent. Even worse e.g. tune2fs or e2fsck can *modify* superblock of a
> mounted filesystem through the block device (e.g. to set 'fsck after X
> mounts' fields and similar).
We've not had any problems when XFS stopped using the block device
address space 9.5 years ago.
next prev parent reply other threads:[~2020-08-27 7:16 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 [this message]
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
2020-08-29 6:40 ` Christoph Hellwig
2020-08-31 7:48 ` Jan Kara
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=20200827071603.GA25305@infradead.org \
--to=hch@infradead.org \
--cc=axboe@kernel.dk \
--cc=jack@suse.cz \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=yebin10@huawei.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.