linux-kernel - Re: [PATCH 5/8] xfs: Protect xfs_file_aio_write() & xfs_setattr_size() with sb_start_write

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Date:	Fri, 03 Feb 2012 22:30:05 -0600
From:	Eric Sandeen <sandeen@...deen.net>
To:	Jan Kara <jack@...e.cz>
CC:	linux-fsdevel@...r.kernel.org, Dave Chinner <dchinner@...hat.com>,
	Surbhi Palande <csurbhi@...il.com>,
	Kamal Mostafa <kamal@...onical.com>,
	Christoph Hellwig <hch@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>, xfs@....sgi.com,
	linux-ext4@...r.kernel.org, Ben Myers <bpm@....com>,
	Alex Elder <elder@...nel.org>
Subject: Re: [PATCH 5/8] xfs: Protect xfs_file_aio_write() & xfs_setattr_size()
 with sb_start_write - sb_end_write

On 1/20/12 2:34 PM, Jan Kara wrote:
> Replace racy xfs_wait_for_freeze() check in xfs_file_aio_write() with
> a reliable sb_start_write() - sb_end_write() locking.

Here's what I'm running with now.  With this and my modified
patch6, I can pass xfstests 068 on xfs.

-Eric



diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 7e5bc87..f1cacdc 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -874,11 +874,11 @@ 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;
 
+	sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
+
 	if (unlikely(file->f_flags & O_DIRECT))
 		ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos, ocount);
 	else
@@ -895,6 +895,7 @@ xfs_file_aio_write(
 		if (err < 0)
 			ret = err;
 	}
+	sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
 
 	return ret;
 }
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index ab30253..7f3fa17 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -773,6 +773,7 @@ xfs_setattr_size(
 			ATTR_MTIME_SET|ATTR_KILL_SUID|ATTR_KILL_SGID|
 			ATTR_KILL_PRIV|ATTR_TIMES_SET)) == 0);
 
+	sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
 	lock_flags = XFS_ILOCK_EXCL;
 	if (!(flags & XFS_ATTR_NOLOCK))
 		lock_flags |= XFS_IOLOCK_EXCL;
@@ -792,6 +793,7 @@ xfs_setattr_size(
 		 * Use the regular setattr path to update the timestamps.
 		 */
 		xfs_iunlock(ip, lock_flags);
+		sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
 		iattr->ia_valid &= ~ATTR_SIZE;
 		return xfs_setattr_nonsize(ip, iattr, 0);
 	}
@@ -938,6 +940,7 @@ xfs_setattr_size(
 out_unlock:
 	if (lock_flags)
 		xfs_iunlock(ip, lock_flags);
+	sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
 	return error;
 
 out_trans_abort:

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