Fix medium change device lookup.

Previously, medium change notifications would be handled with respect
to the wrong emulated disk drive.  This would make many configurations
(particularly ones with CDs and many hard disks) break.  (A medium
change notification occurs at the start for every removeable device.)

Thanks to Haicheng Li at Intel for the report,
 http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1314

diff --git a/xenstore.c b/xenstore.c
index 6c9d4b550ee99c718fd5a891cfbe2829e5072cf9..c0fe95a50db07d022bea3c17464a75ae44179f7a 100644 (file)
--- a/xenstore.c
+++ b/xenstore.c
@@ -92,6 +92,59 @@ static void waitForDevice(char *fn)
     return;
 }
 
+static int any_hdN;
+
+static int parse_drive_name(const char *dev, DriveInfo *out) {
+    /* alway sleaves out->bdrv unchanged */
+    /* on success, returns 0 and fills in out->type, ->bus, ->unit */
+    /* if drive name not understood, returns -1 and *out may be garbage */
+    int ch, max, per_bus;
+
+    /* Change xvdN to look like hdN */
+    if (!any_hdN && !strncmp(dev, "xvd", 3) && strlen(dev) == 4) {
+        ch = dev[3];
+        fprintf(logfile, "Using %s for guest's hd%c\n", dev, ch);
+        out->type = IF_IDE;
+    } else if (!strncmp(dev, "hd", 2) && strlen(dev) == 3) {
+        ch = dev[2];
+        out->type = IF_IDE;
+    } else if (!strncmp(dev, "sd", 2) && strlen(dev) == 3) {
+        ch = dev[2];
+        out->type = IF_SCSI;
+    } else {
+        fprintf(stderr, "qemu: ignoring not-understood drive `%s'\n", dev);
+        return -1;
+    }
+
+    if (out->type == IF_SCSI) {
+        max = MAX_SCSI_DEVS;
+        per_bus = max;
+    } else {
+        max = 4;
+        per_bus = 2;
+    }
+
+    ch = ch - 'a';
+    if (ch >= max) {
+        fprintf(stderr, "qemu: drive `%s' out of range\n", dev);
+        return -1;
+    }
+
+    out->bus = ch / per_bus;
+    out->unit = ch % per_bus;
+    
+    return 0;
+}       
+
+static int drive_name_to_index(const char *name) {
+    DriveInfo tmp;
+    int ret;
+
+    ret = parse_drive_name(name, &tmp);  if (ret) return -1;
+    ret = drive_get_index(tmp.type, tmp.bus, tmp.unit);
+    return ret;
+}
+
 #define DIRECT_PCI_STR_LEN 160
 char direct_pci_str[DIRECT_PCI_STR_LEN];
 void xenstore_parse_domain_config(int hvm_domid)
@@ -100,7 +153,7 @@ void xenstore_parse_domain_config(int hvm_domid)
     char *buf = NULL, *path;
     char *fpath = NULL, *bpath = NULL,
         *dev = NULL, *params = NULL, *type = NULL, *drv = NULL;
-    int i, is_scsi, is_hdN = 0;
+    int i, any_hdN = 0, ret;
     unsigned int len, num, hd_index, pci_devid = 0;
     BlockDriverState *bs;
     BlockDriver *format;
@@ -143,7 +196,7 @@ void xenstore_parse_domain_config(int hvm_domid)
         if (dev == NULL)
             continue;
         if (!strncmp(dev, "hd", 2)) {
-            is_hdN = 1;
+            any_hdN = 1;
             break;
         }
     }
@@ -165,26 +218,13 @@ void xenstore_parse_domain_config(int hvm_domid)
         dev = xs_read(xsh, XBT_NULL, buf, &len);
         if (dev == NULL)
             continue;
-        /* Change xvdN to look like hdN */
-        if (!is_hdN && !strncmp(dev, "xvd", 3)) {
-            fprintf(logfile, "Change xvd%c to look like hd%c\n",
-                    dev[3], dev[3]);
-            memmove(dev, dev+1, strlen(dev));
-            dev[0] = 'h';
-            dev[1] = 'd';
-        }
-        is_scsi = !strncmp(dev, "sd", 2);
-        if ((strncmp(dev, "hd", 2) && !is_scsi) || strlen(dev) != 3 )
-            continue;
-        hd_index = dev[2] - 'a';
        if (nb_drives >= MAX_DRIVES) {
-           fprintf(stderr, "qemu: too many drives\n");
+           fprintf(stderr, "qemu: too many drives, skipping `%s'\n", dev);
            continue;
        }
-        if (hd_index >= (is_scsi ? MAX_SCSI_DEVS : 4)) {
-           fprintf(stderr, "qemu: drives %s out of range\n", dev);
+       ret = parse_drive_name(dev, &drives_table[nb_drives]);
+       if (ret)
            continue;
-       }
         /* read the type of the device */
         if (pasprintf(&buf, "%s/device/vbd/%s/device-type", path, e[i]) == -1)
             continue;
@@ -294,16 +334,6 @@ void xenstore_parse_domain_config(int hvm_domid)
                 fprintf(stderr, "qemu: could not open vbd '%s' or hard disk image '%s' (drv '%s' format '%s')\n", buf, params, drv ? drv : "?", format ? format->format_name : "0");
         }
 
-       assert(nb_drives<MAX_DRIVES);
-       if (is_scsi) {
-           drives_table[nb_drives].type = IF_SCSI;
-           drives_table[nb_drives].bus = 0;
-           drives_table[nb_drives].unit = hd_index;
-       } else {
-           drives_table[nb_drives].type = IF_IDE;
-           drives_table[nb_drives].bus = hd_index / 2;
-           drives_table[nb_drives].unit = hd_index % 2;
-       }
        drives_table[nb_drives].bdrv = bs;
        nb_drives++;
 
@@ -385,7 +415,6 @@ void xenstore_parse_domain_config(int hvm_domid)
         }
     }
 
-
  out:
     free(type);
     free(params);
@@ -624,8 +653,19 @@ void xenstore_process_event(void *opaque)
     if (strncmp(vec[XS_WATCH_TOKEN], "hd", 2) ||
         strlen(vec[XS_WATCH_TOKEN]) != 3)
         goto out;
-    hd_index = vec[XS_WATCH_TOKEN][2] - 'a' - 1;
+
+    hd_index = drive_name_to_index(vec[XS_WATCH_TOKEN]);
+    if (hd_index == -1) {
+       fprintf(stderr,"medium change watch on `%s' -"
+               " unknown device, ignored\n", vec[XS_WATCH_TOKEN]);
+       goto out;
+    }
+
     image = xs_read(xsh, XBT_NULL, vec[XS_WATCH_PATH], &len);
+
+    fprintf(stderr,"medium change watch on `%s' (index: %d): %s\n",
+           vec[XS_WATCH_TOKEN], hd_index, image ? image : "<none>");
+
     if (image == NULL)
         goto out;  /* gone */