From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756056Ab2ATUfX (ORCPT ); Fri, 20 Jan 2012 15:35:23 -0500 Received: from cantor2.suse.de ([195.135.220.15]:44727 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755780Ab2ATUfB (ORCPT ); Fri, 20 Jan 2012 15:35:01 -0500 From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: Eric Sandeen , Dave Chinner , Surbhi Palande , Kamal Mostafa , Christoph Hellwig , LKML , xfs@oss.sgi.com, linux-ext4@vger.kernel.org, Jan Kara , Ben Myers , Alex Elder Subject: [PATCH 5/8] xfs: Protect xfs_file_aio_write() & xfs_setattr_size() with sb_start_write - sb_end_write Date: Fri, 20 Jan 2012 21:34:43 +0100 Message-Id: <1327091686-23177-6-git-send-email-jack@suse.cz> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1327091686-23177-1-git-send-email-jack@suse.cz> References: <1327091686-23177-1-git-send-email-jack@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Replace racy xfs_wait_for_freeze() check in xfs_file_aio_write() with a 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. Similarly we have to protect xfs_setattr_size() because it can modify last page of truncated file. Because ilock is dropped in xfs_setattr_size() we have to drop and retake write access as well to avoid deadlocks. CC: Ben Myers CC: Alex Elder Signed-off-by: Jan Kara --- fs/xfs/xfs_file.c | 6 ++++-- fs/xfs/xfs_iops.c | 6 ++++++ 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 753ed9b..9efd153 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, SB_FREEZE_WRITE); 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, SB_FREEZE_WRITE); /* No fallback to buffered IO on errors for XFS. */ ASSERT(ret < 0 || ret == count); @@ -899,6 +901,7 @@ xfs_file_buffered_aio_write( /* We can write back this queue in page reclaim */ current->backing_dev_info = mapping->backing_dev_info; + sb_start_write(inode->i_sb, SB_FREEZE_WRITE); write_retry: trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0); ret = generic_file_buffered_write(iocb, iovp, nr_segs, @@ -914,6 +917,7 @@ write_retry: enospc = 1; goto write_retry; } + sb_end_write(inode->i_sb, SB_FREEZE_WRITE); current->backing_dev_info = NULL; return ret; } @@ -945,8 +949,6 @@ xfs_file_aio_write( if (ocount == 0) return 0; - xfs_wait_for_freeze(ip->i_mount, SB_FREEZE_WRITE); - if (XFS_FORCED_SHUTDOWN(ip->i_mount)) return -EIO; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 3579bc8..798b9c6 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -793,6 +793,7 @@ xfs_setattr_size( return xfs_setattr_nonsize(ip, iattr, 0); } + sb_start_write(inode->i_sb, SB_FREEZE_WRITE); /* * Make sure that the dquots are attached to the inode. */ @@ -849,10 +850,14 @@ xfs_setattr_size( xfs_get_blocks); if (error) goto out_unlock; + /* Drop the write access to avoid lock inversion with ilock */ + sb_end_write(inode->i_sb, SB_FREEZE_WRITE); xfs_ilock(ip, XFS_ILOCK_EXCL); lock_flags |= XFS_ILOCK_EXCL; + sb_start_write(inode->i_sb, SB_FREEZE_WRITE); + tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_SIZE); error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0, XFS_TRANS_PERM_LOG_RES, @@ -924,6 +929,7 @@ xfs_setattr_size( error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); out_unlock: + sb_end_write(inode->i_sb, SB_FREEZE_WRITE); if (lock_flags) xfs_iunlock(ip, lock_flags); return error; -- 1.7.1