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From 21990bc1a3284a8f06e962f127f8c9f2ad07dc3d Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 19 Jul 2009 08:44:27 -0500
Subject: [PATCH 196/274] fs: namespace preemption fix
On RT we cannot loop with preemption disabled here as
mnt_make_readonly() might have been preempted. We can safely enable
preemption while waiting for MNT_WRITE_HOLD to be cleared. Safe on !RT
as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
fs/namespace.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 4e46539..6dc617c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -313,8 +313,11 @@ int mnt_want_write(struct vfsmount *m)
* incremented count after it has set MNT_WRITE_HOLD.
*/
smp_mb();
- while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
+ while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) {
+ preempt_enable();
cpu_relax();
+ preempt_disable();
+ }
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
* be set to match its requirements. So we must not load that until
--
1.7.10.4
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