Unionfs: lock_rename related locking fixes

CC: Mike Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/rename.c b/fs/unionfs/rename.c
index 9306a2b92b39438e428a6d05b3c2f1198c865d76..5ab13f9f5ec8f1ec796b3bbda2c858fff3ef7a46 100644 (file)
--- a/fs/unionfs/rename.c
+++ b/fs/unionfs/rename.c
@@ -29,6 +29,7 @@ static int __unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
        struct dentry *lower_new_dir_dentry;
        struct dentry *lower_wh_dentry;
        struct dentry *lower_wh_dir_dentry;
+       struct dentry *trap;
        char *wh_name = NULL;
 
        lower_new_dentry = unionfs_lower_dentry_idx(new_dentry, bindex);
@@ -95,6 +96,7 @@ static int __unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                goto out;
 
        dget(lower_old_dentry);
+       dget(lower_new_dentry);
        lower_old_dir_dentry = dget_parent(lower_old_dentry);
        lower_new_dir_dentry = dget_parent(lower_new_dentry);
 
@@ -122,9 +124,20 @@ static int __unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 
        /* see Documentation/filesystems/unionfs/issues.txt */
        lockdep_off();
-       lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+       trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+       /* source should not be ancenstor of target */
+       if (trap == lower_old_dentry) {
+               err = -EINVAL;
+               goto out_err_unlock;
+       }
+       /* target should not be ancenstor of source */
+       if (trap == lower_new_dentry) {
+               err = -ENOTEMPTY;
+               goto out_err_unlock;
+       }
        err = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
                         lower_new_dir_dentry->d_inode, lower_new_dentry);
+out_err_unlock:
        unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
        lockdep_on();
 
@@ -132,6 +145,7 @@ out_dput:
        dput(lower_old_dir_dentry);
        dput(lower_new_dir_dentry);
        dput(lower_old_dentry);
+       dput(lower_new_dentry);
 
 out:
        if (!err) {