From d45f00ae43e63eff1b3d79df20610ae1ef645ebd Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 28 Oct 2014 18:27:28 -0400 Subject: overlayfs: barriers for opening upper-layer directory make sure that a) all stores done by opening struct file don't leak past storing the reference in od->upperfile b) the lockless side has read dependency barrier Signed-off-by: Al Viro --- fs/overlayfs/readdir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 910553f37aca..8c8ce9d87ba3 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -454,12 +454,13 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) { struct inode *inode = file_inode(file); - realfile = od->upperfile; + realfile =lockless_dereference(od->upperfile); if (!realfile) { struct path upperpath; ovl_path_upper(dentry, &upperpath); realfile = ovl_path_open(&upperpath, O_RDONLY); + smp_mb__before_spinlock(); mutex_lock(&inode->i_mutex); if (!od->upperfile) { if (IS_ERR(realfile)) { -- cgit v1.2.3-59-g8ed1b