From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
willy@linux.intel.com
Subject: Re: [PATCH] Sync only the requested range in msync
Date: Mon, 12 May 2014 16:39:48 -0700 [thread overview]
Message-ID: <20140512163948.0b365598e1e4d0b06dea3bc6@linux-foundation.org> (raw)
In-Reply-To: <20140423141115.GA31375@infradead.org>
On Wed, 23 Apr 2014 07:11:15 -0700 Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, Mar 27, 2014 at 07:02:41PM -0400, Matthew Wilcox wrote:
> > [untested. posted because it keeps coming up at lsfmm/collab]
> >
> > msync() currently syncs more than POSIX requires or BSD or Solaris
> > implement. It is supposed to be equivalent to fdatasync(), not fsync(),
> > and it is only supposed to sync the portion of the file that overlaps
> > the range passed to msync.
> >
> > If the VMA is non-linear, fall back to syncing the entire file, but we
> > still optimise to only fdatasync() the entire file, not the full fsync().
> >
> > Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
>
> Looks good,
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
I worry that if there are people who are relying on the current
behaviour (knowingly or not!) then this patch will put their data at
risk and nobody will ever know. Until that data gets lost, that is.
At some level of cautiousness, this is one of those things we can never
fix.
I suppose we could add an msync2() syscall with the new behaviour so
people can migrate over. That would be very cheap to do.
It's hard to know what's the right thing to do here.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-05-12 23:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-27 23:02 [PATCH] Sync only the requested range in msync Matthew Wilcox
2014-04-23 14:11 ` Christoph Hellwig
2014-05-12 23:39 ` Andrew Morton [this message]
2014-05-13 13:31 ` Jeff Moyer
2014-05-15 11:24 ` Christoph Hellwig
2014-05-15 12:50 ` Chris Mason
2014-05-20 22:58 ` Andrew Morton
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=20140512163948.0b365598e1e4d0b06dea3bc6@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=hch@infradead.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.r.wilcox@intel.com \
--cc=willy@linux.intel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).