From ff7a5fb0f1d510997a845e0d227f30831ff38d9d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 7 Jun 2017 17:43:46 +0200
Subject: overlayfs, locking: Remove smp_mb__before_spinlock() usage
While we could replace the smp_mb__before_spinlock() with the new
smp_mb__after_spinlock(), the normal pattern is to use
smp_store_release() to publish an object that is used for
lockless_dereference() -- and mirrors the regular rcu_assign_pointer()
/ rcu_dereference() patterns.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
fs/overlayfs/readdir.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'fs/overlayfs')
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 3d424a51cabb..f0fd3adb1693 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -446,14 +446,14 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
ovl_path_upper(dentry, &upperpath);
realfile = ovl_path_open(&upperpath, O_RDONLY);
- smp_mb__before_spinlock();
+
inode_lock(inode);
if (!od->upperfile) {
if (IS_ERR(realfile)) {
inode_unlock(inode);
return PTR_ERR(realfile);
}
- od->upperfile = realfile;
+ smp_store_release(&od->upperfile, realfile);
} else {
/* somebody has beaten us to it */
if (!IS_ERR(realfile))
--
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