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| author | Al Viro <viro@zeniv.linux.org.uk> | 2014-10-28 18:27:28 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2014-10-28 18:27:28 -0400 |
| commit | d45f00ae43e63eff1b3d79df20610ae1ef645ebd (patch) | |
| tree | 49b273720e044e74116a2d98668a11aac49a3214 /fs/overlayfs/readdir.c | |
| parent | 54ef6df3f3f1353d99c80c437259d317b2cd1cbd (diff) | |
| download | lwn-d45f00ae43e63eff1b3d79df20610ae1ef645ebd.tar.gz lwn-d45f00ae43e63eff1b3d79df20610ae1ef645ebd.zip | |
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 <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/overlayfs/readdir.c')
| -rw-r--r-- | fs/overlayfs/readdir.c | 3 |
1 files changed, 2 insertions, 1 deletions
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)) { |