Fix lseek result when dnode is dirty

Fixup commit 99b2905

We should have equivalent return values as generic_file_llseek()

Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>

module/zfs/zfs_vnops.c

@@ -278,9 +278,13 @@ zfs_holey_common(struct inode *ip, int cmd, loff_t *off)
 	if (error == ESRCH)
 		return (SET_ERROR(ENXIO));
 
-	/* file was dirty, so fall back to using file_sz logic */
-	if (error == EBUSY)
-		error = 0;
+	/* file was dirty, so fall back to using generic logic */
+	if (error == EBUSY) {
+		if (hole)
+			*off = file_sz;
+
+		return (0);
+	}
 
 	/*
 	 * We could find a hole that begins after the logical end-of-file,