fix reiserfs mkdir() breakage

if directory has so many subdirectories that its link count is set
to 1 (i.e. "can't tell accurately") and reiserfs_new_inode() fails,
we shouldn't decrement the parent's link count in cleanup path;
that's what DEC_DIR_INODE_NLINK() is for.  As it is, we end up
with parent suddenly getting zero i_nlink, with very unpleasant
effects.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/reiserfs/namei.c

@@ -771,7 +771,7 @@ static int reiserfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 					EMPTY_DIR_SIZE_V1 : EMPTY_DIR_SIZE,
 					dentry, inode, &security);
 	if (retval) {
-		dir->i_nlink--;
+		DEC_DIR_INODE_NLINK(dir)
 		goto out_failed;
 	}