From ff7a5fb0f1d510997a845e0d227f30831ff38d9d Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 7 Jun 2017 17:43:46 +0200 Subject: [PATCH] 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) Cc: Al Viro Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- fs/overlayfs/readdir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) 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)) -- 2.39.5