Date: Thu, 2 Apr 2009 12:37:12 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: David Howells <dhowells@redhat.com>, hch@infradead.org,
       viro@zeniv.linux.org.uk, nfsv4@linux-nfs.org,
       linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 22/43] CacheFiles: Add a hook to write a single page of
	data to an inode [ver #46]
Message-ID: <20090402163712.GA25177@infradead.org>
References: <200904030100.05741.nickpiggin@yahoo.com.au> <20090401230515.28177.73948.stgit@warthog.procyon.org.uk> <5564.1238684153@redhat.com> <200904030232.59355.nickpiggin@yahoo.com.au>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <200904030232.59355.nickpiggin@yahoo.com.au>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 814
Lines: 17

On Fri, Apr 03, 2009 at 02:32:58AM +1100, Nick Piggin wrote:
> Hmm, I guess not all filesystems define write_begin/write_end. But if you
> only need to use ones that do define them?

No.  write_begin/write_end are simply callbacks for the write helpers,
and locking for them is entirely filesystem-defined.  E.g. xfs and the
cluster filesystems require additional locks taken first, and some
network filesystems require inode revalidations first.

They really should be taken out of the address_space_operations and
passed as callbacks to generic_file_aio_write & co.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/