Subject: CDROM removable media-present attribute plus handling code
From: plc@novell.com
Patch-mainline: obsolete
References: 159907

Index: head-2008-05-08/drivers/xen/blkback/Makefile
===================================================================
--- head-2008-05-08.orig/drivers/xen/blkback/Makefile	2008-05-08 15:34:23.000000000 +0200
+++ head-2008-05-08/drivers/xen/blkback/Makefile	2008-05-08 15:05:13.000000000 +0200
@@ -1,3 +1,3 @@
 obj-$(CONFIG_XEN_BLKDEV_BACKEND) := blkbk.o
 
-blkbk-y	:= blkback.o xenbus.o interface.o vbd.o
+blkbk-y	:= blkback.o xenbus.o interface.o vbd.o cdrom.o
Index: head-2008-05-08/drivers/xen/blkback/cdrom.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ head-2008-05-08/drivers/xen/blkback/cdrom.c	2008-05-13 15:34:40.000000000 +0200
@@ -0,0 +1,162 @@
+/******************************************************************************
+ * blkback/cdrom.c
+ *
+ * Routines for managing cdrom watch and media-present attribute of a
+ * cdrom type virtual block device (VBD).
+ *
+ * Copyright (c) 2003-2005, Keir Fraser & Steve Hand
+ * Copyright (c) 2007       Pat Campbell
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "common.h"
+
+#undef DPRINTK
+#define DPRINTK(_f, _a...)			\
+	printk("(%s() file=%s, line=%d) " _f "\n",	\
+		 __PRETTY_FUNCTION__, __FILE__ , __LINE__ , ##_a )
+
+
+#define MEDIA_PRESENT "media-present"
+
+static void cdrom_media_changed(struct xenbus_watch *, const char **, unsigned int);
+
+/**
+ * Writes media-present=1 attribute for the given vbd device if not
+ * already there
+ */
+static int cdrom_xenstore_write_media_present(struct backend_info *be)
+{
+	struct xenbus_device *dev = be->dev;
+	struct xenbus_transaction xbt;
+	int err;
+	int media_present;
+
+	err = xenbus_scanf(XBT_NIL, dev->nodename, MEDIA_PRESENT, "%d",
+			   &media_present);
+	if (0 < err) {
+		DPRINTK("already written err%d", err);
+		return(0);
+	}
+	media_present = 1;
+
+again:
+	err = xenbus_transaction_start(&xbt);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "starting transaction");
+		return(-1);
+	}
+
+	err = xenbus_printf(xbt, dev->nodename, MEDIA_PRESENT, "%d", media_present );
+	if (err) {
+		xenbus_dev_fatal(dev, err, "writing %s/%s",
+			 dev->nodename, MEDIA_PRESENT);
+		goto abort;
+	}
+	err = xenbus_transaction_end(xbt, 0);
+	if (err == -EAGAIN)
+		goto again;
+	if (err)
+		xenbus_dev_fatal(dev, err, "ending transaction");
+	return 0;
+ abort:
+	xenbus_transaction_end(xbt, 1);
+	return -1;
+}
+
+/**
+ *
+ */
+static int cdrom_is_type(struct backend_info *be)
+{
+	DPRINTK("type:%x", be->blkif->vbd.type );
+	return (be->blkif->vbd.type & VDISK_CDROM)
+	       && (be->blkif->vbd.type & GENHD_FL_REMOVABLE);
+}
+
+/**
+ *
+ */
+void cdrom_add_media_watch(struct backend_info *be)
+{
+	struct xenbus_device *dev = be->dev;
+	int err;
+
+	DPRINTK("nodename:%s", dev->nodename);
+	if (cdrom_is_type(be)) {
+		DPRINTK("is a cdrom");
+		if ( cdrom_xenstore_write_media_present(be) == 0 ) {
+			DPRINTK( "xenstore wrote OK");
+			err = xenbus_watch_path2(dev, dev->nodename, MEDIA_PRESENT,
+						 &be->backend_cdrom_watch,
+						 cdrom_media_changed);
+			if (err)
+				DPRINTK( "media_present watch add failed" );
+		}
+	}
+}
+
+/**
+ * Callback received when the "media_present" xenstore node is changed
+ */
+static void cdrom_media_changed(struct xenbus_watch *watch,
+				const char **vec, unsigned int len)
+{
+	int err;
+	unsigned media_present;
+	struct backend_info *be
+		= container_of(watch, struct backend_info, backend_cdrom_watch);
+	struct xenbus_device *dev = be->dev;
+
+	if (!cdrom_is_type(be)) {
+		DPRINTK("callback not for a cdrom" );
+		return;
+	}
+
+	err = xenbus_scanf(XBT_NIL, dev->nodename, MEDIA_PRESENT, "%d",
+			   &media_present);
+	if (err == 0 || err == -ENOENT) {
+		DPRINTK("xenbus_read of cdrom media_present node error:%d",err);
+		return;
+	}
+
+	if (media_present == 0)
+		vbd_free(&be->blkif->vbd);
+	else {
+		char *p = strrchr(dev->otherend, '/') + 1;
+		long handle = simple_strtoul(p, NULL, 0);
+
+		if (!be->blkif->vbd.bdev) {
+			err = vbd_create(be->blkif, handle, be->major, be->minor,
+					 !strchr(be->mode, 'w'), 1);
+			if (err) {
+				be->major = be->minor = 0;
+				xenbus_dev_fatal(dev, err, "creating vbd structure");
+				return;
+			}
+		}
+	}
+}
Index: head-2008-05-08/drivers/xen/blkback/common.h
===================================================================
--- head-2008-05-08.orig/drivers/xen/blkback/common.h	2008-05-08 15:34:23.000000000 +0200
+++ head-2008-05-08/drivers/xen/blkback/common.h	2008-05-13 15:35:13.000000000 +0200
@@ -96,6 +96,17 @@ typedef struct blkif_st {
 	grant_ref_t    shmem_ref;
 } blkif_t;
 
+struct backend_info
+{
+	struct xenbus_device *dev;
+	blkif_t *blkif;
+	struct xenbus_watch backend_watch;
+	struct xenbus_watch backend_cdrom_watch;
+	unsigned major;
+	unsigned minor;
+	char *mode;
+};
+
 blkif_t *blkif_alloc(domid_t domid);
 void blkif_disconnect(blkif_t *blkif);
 void blkif_free(blkif_t *blkif);
@@ -136,4 +147,7 @@ int blkif_schedule(void *arg);
 int blkback_barrier(struct xenbus_transaction xbt,
 		    struct backend_info *be, int state);
 
+/* cdrom media change */
+void cdrom_add_media_watch(struct backend_info *be);
+
 #endif /* __BLKIF__BACKEND__COMMON_H__ */
Index: head-2008-05-08/drivers/xen/blkback/vbd.c
===================================================================
--- head-2008-05-08.orig/drivers/xen/blkback/vbd.c	2008-05-08 15:34:23.000000000 +0200
+++ head-2008-05-08/drivers/xen/blkback/vbd.c	2008-05-08 15:05:13.000000000 +0200
@@ -106,6 +106,9 @@ int vbd_translate(struct phys_req *req, 
 	if ((operation != READ) && vbd->readonly)
 		goto out;
 
+	if (vbd->bdev == NULL)
+		goto out;
+
 	if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
 		goto out;
 
Index: head-2008-05-08/drivers/xen/blkback/xenbus.c
===================================================================
--- head-2008-05-08.orig/drivers/xen/blkback/xenbus.c	2008-05-08 15:34:23.000000000 +0200
+++ head-2008-05-08/drivers/xen/blkback/xenbus.c	2008-05-08 15:05:13.000000000 +0200
@@ -28,16 +28,6 @@
 	pr_debug("blkback/xenbus (%s:%d) " fmt ".\n",	\
 		 __FUNCTION__, __LINE__, ##args)
 
-struct backend_info
-{
-	struct xenbus_device *dev;
-	blkif_t *blkif;
-	struct xenbus_watch backend_watch;
-	unsigned major;
-	unsigned minor;
-	char *mode;
-};
-
 static void connect(struct backend_info *);
 static int connect_ring(struct backend_info *);
 static void backend_changed(struct xenbus_watch *, const char **,
@@ -183,6 +173,12 @@ static int blkback_remove(struct xenbus_
 		be->backend_watch.node = NULL;
 	}
 
+	if (be->backend_cdrom_watch.node) {
+		unregister_xenbus_watch(&be->backend_cdrom_watch);
+		kfree(be->backend_cdrom_watch.node);
+		be->backend_cdrom_watch.node = NULL;
+	}
+
 	if (be->blkif) {
 		blkif_disconnect(be->blkif);
 		vbd_free(&be->blkif->vbd);
@@ -339,6 +335,9 @@ static void backend_changed(struct xenbu
 
 		/* We're potentially connected now */
 		update_blkif_status(be->blkif);
+
+		/* Add watch for cdrom media status if necessay */
+		cdrom_add_media_watch(be);
 	}
 }