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31 lines
962 B
Diff
31 lines
962 B
Diff
From: Thomas Gleixner <tglx@linutronix.de>
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Date: Sun, 19 Jul 2009 08:44:27 -0500
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Subject: fs: namespace preemption fix
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On RT we cannot loop with preemption disabled here as
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mnt_make_readonly() might have been preempted. We can safely enable
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preemption while waiting for MNT_WRITE_HOLD to be cleared. Safe on !RT
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as well.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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fs/namespace.c | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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--- a/fs/namespace.c
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+++ b/fs/namespace.c
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@@ -353,8 +353,11 @@ int __mnt_want_write(struct vfsmount *m)
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* incremented count after it has set MNT_WRITE_HOLD.
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*/
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smp_mb();
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- while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
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+ while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) {
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+ preempt_enable();
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cpu_relax();
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+ preempt_disable();
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+ }
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/*
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* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
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* be set to match its requirements. So we must not load that until
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