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vfs, freeze: use ACCESS_ONCE() to guard access to ->mnt_flags 

The compiler may optimize the while loop and make the check just be done once,
so we should use ACCESS_ONCE() to guard access to ->mnt_flags

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miao Xie 2012-11-16 17:23:50 +08:00 committed by Al Viro
parent f01af9f858
commit 1e75529e3c
1 changed files with 1 additions and 1 deletions
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2
fs/namespace.c
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@ -313,7 +313,7 @@ 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 (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
cpu_relax();
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will