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[PATCH] disable queue flag test in barrier check

To: xfs-oss <xfs@xxxxxxxxxxx>
Subject: [PATCH] disable queue flag test in barrier check
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Wed, 25 Jun 2008 22:07:22 -0500
Cc: LinuxRaid <linux-raid@xxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Thunderbird (Macintosh/20080421)
md raid1 can pass down barriers, but does not set an ordered flag 
on the queue, so xfs does not even attempt a barrier write, and 
will never use barriers on these block devices.

I propose removing the flag check and just let the barrier write
test determine barrier support.

The risk here, I suppose, is that if something does not set an ordered
flag and also does not properly return an error on a barrier write...
but if it's any consolation jbd/ext3/reiserfs never test the flag, 
and don't even do a test write, they just disable barriers the first 
time an actual journal barrier write fails.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxxx>

Index: linux-
--- linux-
+++ linux-
@@ -733,14 +733,6 @@ xfs_mountfs_check_barriers(xfs_mount_t *
-       if (mp->m_ddev_targp->bt_bdev->bd_disk->queue->ordered ==
-                                       QUEUE_ORDERED_NONE) {
-               xfs_fs_cmn_err(CE_NOTE, mp,
-                 "Disabling barriers, not supported by the underlying device");
-               mp->m_flags &= ~XFS_MOUNT_BARRIER;
-               return;
-       }
        if (xfs_readonly_buftarg(mp->m_ddev_targp)) {
                xfs_fs_cmn_err(CE_NOTE, mp,
                  "Disabling barriers, underlying device is readonly");

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