From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 4/4] xfs: Protect xfs_file_aio_write() with sb_start_write - sb_end_write Date: Thu, 12 Jan 2012 22:36:56 +0100 Message-ID: <20120112213656.GF8778@quack.suse.cz> References: <1326331253-6497-1-git-send-email-jack@suse.cz> <1326331253-6497-5-git-send-email-jack@suse.cz> <20120112212941.GI23916@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , linux-fsdevel@vger.kernel.org, LKML , linux-ext4@vger.kernel.org, xfs@oss.sgi.com, Eric Sandeen , Dave Chinner , Surbhi Palande , Kamal Mostafa , Christoph Hellwig , Ben Myers , Alex Elder To: Al Viro Return-path: Content-Disposition: inline In-Reply-To: <20120112212941.GI23916@ZenIV.linux.org.uk> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu 12-01-12 21:29:41, Al Viro wrote: > On Thu, Jan 12, 2012 at 02:20:53AM +0100, Jan Kara wrote: > > Replace racy xfs_wait_for_freeze() check with reliable sb_start_write() > > - sb_end_write() locking. Due to lock ranking dictated by the page fault > > code we have to call sb_start_write() after we acquire ilock. > > > > CC: Ben Myers > > CC: Alex Elder > > Signed-off-by: Jan Kara > > --- > > fs/xfs/xfs_file.c | 6 ++++-- > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > > index 753ed9b..c5f879b 100644 > > --- a/fs/xfs/xfs_file.c > > +++ b/fs/xfs/xfs_file.c > > @@ -862,9 +862,11 @@ xfs_file_dio_aio_write( > > *iolock = XFS_IOLOCK_SHARED; > > } > > > > + sb_start_write(inode->i_sb); > > trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0); > > ret = generic_file_direct_write(iocb, iovp, > > &nr_segs, pos, &iocb->ki_pos, count, ocount); > > + sb_end_write(inode->i_sb); > > What lock ordering do you have in mind? Explicit description in fs/super.c, > please... Good point. Will add explanatory comment. Thanks. Honza -- Jan Kara SUSE Labs, CR