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-rw-r--r--fs/overlayfs/util.c19
1 files changed, 19 insertions, 0 deletions
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;
+}