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

--- head.orig/drivers/xen/blkback/Makefile	2009-06-09 15:01:37.000000000 +0200
+++ head/drivers/xen/blkback/Makefile	2010-03-25 14:38:02.000000000 +0100
@@ -1,4 +1,4 @@
 obj-$(CONFIG_XEN_BLKDEV_BACKEND) := blkbk.o
 obj-$(CONFIG_XEN_BLKBACK_PAGEMAP) += blkback-pagemap.o
 
-blkbk-y	:= blkback.o xenbus.o interface.o vbd.o
+blkbk-y	:= blkback.o xenbus.o interface.o vbd.o cdrom.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ head/drivers/xen/blkback/cdrom.c	2011-05-27 17:41:57.000000000 +0200
@@ -0,0 +1,154 @@
+/******************************************************************************
+ * 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"
+
+#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 = !!be->blkif->vbd.bdev;
+
+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->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, media_present;
+	struct backend_info *be
+		= container_of(watch, struct backend_info, 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) {
+		DPRINTK("read of " MEDIA_PRESENT " node error:%d", err);
+		return;
+	}
+
+	if (!media_present)
+		vbd_free(&be->blkif->vbd);
+	else if (!be->blkif->vbd.bdev) {
+		char *p = strrchr(dev->otherend, '/') + 1;
+		long handle = simple_strtoul(p, NULL, 0);
+
+		err = vbd_create(be->blkif, handle, be->major, be->minor,
+				 be->blkif->vbd.mode, true);
+		if (err && err != -ENOMEDIUM) {
+			be->major = be->minor = 0;
+			xenbus_dev_fatal(dev, err, "creating vbd structure");
+			return;
+		}
+		vbd_resize(be->blkif);
+	}
+}
--- head.orig/drivers/xen/blkback/common.h	2012-06-08 10:38:21.000000000 +0200
+++ head/drivers/xen/blkback/common.h	2012-06-08 10:40:03.000000000 +0200
@@ -101,6 +101,7 @@ struct backend_info
 	struct xenbus_device *dev;
 	blkif_t *blkif;
 	struct xenbus_watch backend_watch;
+	struct xenbus_watch cdrom_watch;
 	unsigned major;
 	unsigned minor;
 	char *mode;
@@ -148,4 +149,7 @@ void blkback_barrier(struct xenbus_trans
 void blkback_flush_diskcache(struct xenbus_transaction,
 			     struct backend_info *, int state);
 
+/* cdrom media change */
+void cdrom_add_media_watch(struct backend_info *be);
+
 #endif /* __BLKIF__BACKEND__COMMON_H__ */
--- head.orig/drivers/xen/blkback/vbd.c	2012-02-27 10:22:57.000000000 +0100
+++ head/drivers/xen/blkback/vbd.c	2012-02-27 10:29:18.000000000 +0100
@@ -37,12 +37,12 @@
 
 unsigned long long vbd_size(struct vbd *vbd)
 {
-	return vbd_sz(vbd);
+	return vbd->bdev ? vbd_sz(vbd) : 0;
 }
 
 unsigned long vbd_secsize(struct vbd *vbd)
 {
-	return bdev_logical_block_size(vbd->bdev);
+	return vbd->bdev ? bdev_logical_block_size(vbd->bdev) : 0;
 }
 
 int vbd_create(blkif_t *blkif, blkif_vdev_t handle, unsigned major,
@@ -54,7 +54,8 @@ int vbd_create(blkif_t *blkif, blkif_vde
 
 	vbd = &blkif->vbd;
 	vbd->handle   = handle; 
-	vbd->type     = 0;
+	vbd->size     = 0;
+	vbd->type     = cdrom ? VDISK_CDROM : 0;
 
 	if (!(mode & FMODE_WRITE)) {
 		mode &= ~FMODE_EXCL; /* xend doesn't even allow mode="r!" */
@@ -67,9 +68,31 @@ int vbd_create(blkif_t *blkif, blkif_vde
 	bdev = blkdev_get_by_dev(vbd->pdevice, mode, blkif);
 
 	if (IS_ERR(bdev)) {
-		DPRINTK("vbd_creat: device %08x could not be opened.\n",
+		if (PTR_ERR(bdev) != -ENOMEDIUM) {
+			DPRINTK("vbd_creat: device %08x could not be opened\n",
+				vbd->pdevice);
+			return -ENOENT;
+		}
+
+		DPRINTK("vbd_creat: device %08x has no medium\n",
 			vbd->pdevice);
-		return -ENOENT;
+		if (cdrom)
+			return -ENOMEDIUM;
+
+		bdev = blkdev_get_by_dev(vbd->pdevice, mode | FMODE_NDELAY,
+					 blkif);
+		if (IS_ERR(bdev))
+			return -ENOMEDIUM;
+
+		if (bdev->bd_disk) {
+			if (bdev->bd_disk->flags & GENHD_FL_CD)
+				vbd->type |= VDISK_CDROM;
+			if (bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
+				vbd->type |= VDISK_REMOVABLE;
+		}
+
+		blkdev_put(bdev, mode);
+		return -ENOMEDIUM;
 	}
 
 	vbd->bdev = bdev;
@@ -83,7 +106,7 @@ int vbd_create(blkif_t *blkif, blkif_vde
 
 	vbd->size = vbd_size(vbd);
 
-	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
+	if (bdev->bd_disk->flags & GENHD_FL_CD)
 		vbd->type |= VDISK_CDROM;
 	if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
 		vbd->type |= VDISK_REMOVABLE;
@@ -115,6 +138,11 @@ int vbd_translate(struct phys_req *req, 
 	if ((operation != READ) && !(vbd->mode & FMODE_WRITE))
 		goto out;
 
+	if (vbd->bdev == NULL) {
+		rc = -ENOMEDIUM;
+		goto out;
+	}
+
 	if (likely(req->nr_sects)) {
 		blkif_sector_t end = req->sector_number + req->nr_sects;
 
@@ -154,6 +182,14 @@ again:
 		pr_warning("Error %d writing new size", err);
 		goto abort;
 	}
+
+	err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
+			    vbd_secsize(vbd));
+	if (err) {
+		pr_warning("Error writing new sector size");
+		goto abort;
+	}
+
 	/*
 	 * Write the current state; we will use this to synchronize
 	 * the front-end. If the current state is "connected" the
--- head.orig/drivers/xen/blkback/xenbus.c	2012-03-26 15:54:30.000000000 +0200
+++ head/drivers/xen/blkback/xenbus.c	2012-03-26 15:55:24.000000000 +0200
@@ -58,7 +58,7 @@ static void update_blkif_status(blkif_t 
 	char name[TASK_COMM_LEN];
 
 	/* Not ready to connect? */
-	if (!blkif->irq || !blkif->vbd.bdev)
+	if (!blkif->irq)
 		return;
 
 	/* Already connected? */
@@ -76,12 +76,17 @@ static void update_blkif_status(blkif_t 
 		return;
 	}
 
-	err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
-	if (err) {
-		xenbus_dev_error(blkif->be->dev, err, "block flush");
-		return;
+	if (blkif->vbd.bdev) {
+		struct address_space *mapping
+			= blkif->vbd.bdev->bd_inode->i_mapping;
+
+		err = filemap_write_and_wait(mapping);
+		if (err) {
+			xenbus_dev_error(blkif->be->dev, err, "block flush");
+			return;
+		}
+		invalidate_inode_pages2(mapping);
 	}
-	invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
 
 	blkif->xenblkd = kthread_run(blkif_schedule, blkif, name);
 	if (IS_ERR(blkif->xenblkd)) {
@@ -190,6 +195,12 @@ static int blkback_remove(struct xenbus_
 		be->backend_watch.node = NULL;
 	}
 
+	if (be->cdrom_watch.node) {
+		unregister_xenbus_watch(&be->cdrom_watch);
+		kfree(be->cdrom_watch.node);
+		be->cdrom_watch.node = NULL;
+	}
+
 	if (be->blkif) {
 		blkif_disconnect(be->blkif);
 		vbd_free(&be->blkif->vbd);
@@ -379,7 +390,13 @@ static void backend_changed(struct xenbu
 				 | (strchr(be->mode, 'w') ? FMODE_WRITE : 0)
 				 | (strchr(be->mode, '!') ? 0 : FMODE_EXCL),
 				 cdrom);
-		if (err) {
+		switch (err) {
+		case -ENOMEDIUM:
+			if (be->blkif->vbd.type
+			    & (VDISK_CDROM | VDISK_REMOVABLE))
+		case 0:
+				break;
+		default:
 			be->major = be->minor = 0;
 			xenbus_dev_fatal(dev, err, "creating vbd structure");
 			return;
@@ -395,6 +412,9 @@ 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);
 	}
 }
 
@@ -435,7 +455,8 @@ static void frontend_changed(struct xenb
 		err = connect_ring(be);
 		if (err)
 			break;
-		update_blkif_status(be->blkif);
+		if (be->blkif->vbd.bdev)
+			update_blkif_status(be->blkif);
 		break;
 
 	case XenbusStateClosing: