Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753198AbYCRIRH (ORCPT ); Tue, 18 Mar 2008 04:17:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751456AbYCRIQw (ORCPT ); Tue, 18 Mar 2008 04:16:52 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:49720 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751395AbYCRIQv (ORCPT ); Tue, 18 Mar 2008 04:16:51 -0400 To: akpm@linux-foundation.org CC: miklos@szeredi.hu, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org In-reply-to: <20080317220821.d0adb692.akpm@linux-foundation.org> (message from Andrew Morton on Mon, 17 Mar 2008 22:08:21 -0700) Subject: Re: [patch 6/8] fuse: clean up setting i_size in write References: <20080317191908.123631326@szeredi.hu> <20080317191947.989369784@szeredi.hu> <20080317220821.d0adb692.akpm@linux-foundation.org> Message-Id: From: Miklos Szeredi Date: Tue, 18 Mar 2008 09:16:49 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2075 Lines: 64 > On Mon, 17 Mar 2008 20:19:14 +0100 Miklos Szeredi wrote: > > > From: Miklos Szeredi > > > > Extract common code for setting i_size in write functions into a > > common helper. > > > > Signed-off-by: Miklos Szeredi > > --- > > fs/fuse/file.c | 28 +++++++++++++++------------- > > 1 file changed, 15 insertions(+), 13 deletions(-) > > > > Index: linux/fs/fuse/file.c > > =================================================================== > > --- linux.orig/fs/fuse/file.c 2008-03-17 18:26:04.000000000 +0100 > > +++ linux/fs/fuse/file.c 2008-03-17 18:26:28.000000000 +0100 > > @@ -610,13 +610,24 @@ static int fuse_write_begin(struct file > > return 0; > > } > > > > +static void fuse_write_update_size(struct inode *inode, loff_t pos) > > +{ > > + struct fuse_conn *fc = get_fuse_conn(inode); > > + struct fuse_inode *fi = get_fuse_inode(inode); > > + > > + spin_lock(&fc->lock); > > + fi->attr_version = ++fc->attr_version; > > + if (pos > inode->i_size) > > + i_size_write(inode, pos); > > + spin_unlock(&fc->lock); > > +} > > > > ... > > > > @@ -766,12 +772,8 @@ static ssize_t fuse_direct_io(struct fil > > } > > fuse_put_request(fc, req); > > if (res > 0) { > > - if (write) { > > - spin_lock(&fc->lock); > > - if (pos > inode->i_size) > > - i_size_write(inode, pos); > > - spin_unlock(&fc->lock); > > - } > > + if (write) > > + fuse_write_update_size(inode, pos); > > We require that i_mutex be held here, to prevent i_size_write() deadlocks. > Is it held? > No, fuse uses the per connection spinlock to protect against concurrent calls to i_size_write(), because in some cases holding i_mutex would be difficult. Fuse already got painfully bitten by the i_size_write() deadlock, so I'm well aware of the problem :) Miklos -- 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/