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Commit 1e75529e authored by Miao Xie's avatar Miao Xie Committed by Al Viro
Browse files

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: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f01af9f8

fs/namespace.c

+1 −1
Original line number Diff line number Diff line
@@ -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