ovl: fix missing unlock_rename() in ovl_do_copy_up()

Use the ovl_lock_rename_workdir() helper which requires
unlock_rename() only on lock success.

Fixes: ("fd210b7d67ee ovl: move copy up lock out")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

4 files changed, 22 insertions, 24 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index aad97b30d5e6..c441f9387a1b 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -561,10 +561,8 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
                 c->tmpfile = true;
                 err = ovl_copy_up_locked(c);
         } else {
-                err = -EIO;
-                if (lock_rename(c->workdir, c->destdir) != NULL) {
-                        pr_err("overlayfs: failed to lock workdir+upperdir\n");
-                } else {
+                err = ovl_lock_rename_workdir(c->workdir, c->destdir);
+                if (!err) {
                         err = ovl_copy_up_locked(c);
                         unlock_rename(c->workdir, c->destdir);
                 }
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 3309b1912241..cc961a3bd3bd 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -216,26 +216,6 @@ out_unlock:
         return err;
 }
 
-static int ovl_lock_rename_workdir(struct dentry *workdir,
-                                   struct dentry *upperdir)
-{
-        /* Workdir should not be the same as upperdir */
-        if (workdir == upperdir)
-                goto err;
-
-        /* Workdir should not be subdir of upperdir and vice versa */
-        if (lock_rename(workdir, upperdir) != NULL)
-                goto err_unlock;
-
-        return 0;
-
-err_unlock:
-        unlock_rename(workdir, upperdir);
-err:
-        pr_err("overlayfs: failed to lock workdir+upperdir\n");
-        return -EIO;
-}
-
 static struct dentry *ovl_clear_empty(struct dentry *dentry,
                                       struct list_head *list)
 {
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d4e8c1a08fb0..c706a6f99928 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -235,6 +235,7 @@ bool ovl_inuse_trylock(struct dentry *dentry);
 void ovl_inuse_unlock(struct dentry *dentry);
 int ovl_nlink_start(struct dentry *dentry, bool *locked);
 void ovl_nlink_end(struct dentry *dentry, bool locked);
+int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
 
 static inline bool ovl_is_impuredir(struct dentry *dentry)
 {
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 7ae33d225a67..b9b239fa5cfd 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -560,3 +560,22 @@ void ovl_nlink_end(struct dentry *dentry, bool locked)
                 mutex_unlock(&OVL_I(d_inode(dentry))->lock);
         }
 }
+
+int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
+{
+        /* Workdir should not be the same as upperdir */
+        if (workdir == upperdir)
+                goto err;
+
+        /* Workdir should not be subdir of upperdir and vice versa */
+        if (lock_rename(workdir, upperdir) != NULL)
+                goto err_unlock;
+
+        return 0;
+
+err_unlock:
+        unlock_rename(workdir, upperdir);
+err:
+        pr_err("overlayfs: failed to lock workdir+upperdir\n");
+        return -EIO;
+}