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From: Christoph Hellwig <>
To: Nick Piggin <>
Cc:,,, Roman Zippel <>,
	"Tigran A. Aivazian" <>,
	Boaz Harrosh <>,
	OGAWA Hirofumi <>,
	Dave Kleikamp <>,
	Bob Copeland <>,,
	Christoph Hellwig <>,
	Evgeniy Dushistov <>, Jan Kara <>
Subject: Re: [RFC][PATCH] Possible data integrity problems in lots of filesystems?
Date: Thu, 25 Nov 2010 07:01:33 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20101125115457.GB3643@amd>

On Thu, Nov 25, 2010 at 10:54:57PM +1100, Nick Piggin wrote:
> On Thu, Nov 25, 2010 at 06:49:09PM +1100, Nick Piggin wrote:
> > Second is confusing sync and async inode metadata writeout
> > Core code clears I_DIRTY_SYNC and I_DIRTY_DATASYNC before calling
> > ->write_inode *regardless* of whether it is a for-integrity call or
> > not. This means background writeback can clear it, and subsequent
> > sync_inode_metadata or sync(2) call will skip the next ->write_inode
> > completely.
> Hmm, this also means that write_inode_now(sync=1) is buggy. It
> needs to in fact call ->fsync -- which is a file operation
> unfortunately, Christoph didn't you have some patches to move it
> into an inode operation?

No, it doesn't really make much sense either.  But what I've slowly
started doing is to phase out write_inode_now.  For the cases where
we really only want to write the inode we should use
sync_inode_metadata.  That only leaves two others callsers:

 - iput_final for a filesystem during unmount.  This should be caught
   by the need to call ->sync_fs rule you mentioned above, but needs
   a closer audit.
 - nfsd.  Any filesystem that cares should just use the commit_metadata
   export operations, which is a subsystem of ->fsync as it only need
   to guarantee that metadata is on disk, but not actually any file
   data - so no cache flush mess as in a real fsync implementation.

      reply	other threads:[~2010-11-25 12:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-25  7:49 [RFC][PATCH] Possible data integrity problems in lots of filesystems? Nick Piggin
2010-11-25  9:28 ` Boaz Harrosh
2010-11-25 10:06   ` Nick Piggin
2010-11-25 10:51     ` Boaz Harrosh
2010-11-25 10:52       ` [PATCH] exofs: simple fsync race fix Boaz Harrosh
2010-11-25 11:50         ` Nick Piggin
2011-02-03 11:44           ` Boaz Harrosh
2010-11-25 11:47       ` [RFC][PATCH] Possible data integrity problems in lots of filesystems? Nick Piggin
2010-11-25 12:18         ` Boaz Harrosh
2010-11-25 11:54 ` Nick Piggin
2010-11-25 12:01   ` Christoph Hellwig [this message]

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