3 files changed, 60 insertions, 1 deletions

diff --git a/block/genhd.c b/block/genhd.c
index b5664440896c..93a2cf654597 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -213,6 +213,59 @@ struct gendisk *get_gendisk(dev_t dev, int *part)
         return  kobj ? to_disk(kobj) : NULL;
 }
 
+/*
+ * print a full list of all partitions - intended for places where the root
+ * filesystem can't be mounted and thus to give the victim some idea of what
+ * went wrong
+ */
+void __init printk_all_partitions(void)
+{
+        int n;
+        struct gendisk *sgp;
+
+        mutex_lock(&block_subsys_lock);
+        /* For each block device... */
+        list_for_each_entry(sgp, &block_subsys.list, kobj.entry) {
+                char buf[BDEVNAME_SIZE];
+                /*
+                 * Don't show empty devices or things that have been surpressed
+                 */
+                if (get_capacity(sgp) == 0 ||
+                    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
+                        continue;
+
+                /*
+                 * Note, unlike /proc/partitions, I am showing the numbers in
+                 * hex - the same format as the root= option takes.
+                 */
+                printk("%02x%02x %10llu %s",
+                        sgp->major, sgp->first_minor,
+                        (unsigned long long)get_capacity(sgp) >> 1,
+                        disk_name(sgp, 0, buf));
+                if (sgp->driverfs_dev != NULL &&
+                    sgp->driverfs_dev->driver != NULL)
+                        printk(" driver: %s\n",
+                                sgp->driverfs_dev->driver->name);
+                else
+                        printk(" (driver?)\n");
+
+                /* now show the partitions */
+                for (n = 0; n < sgp->minors - 1; ++n) {
+                        if (sgp->part[n] == NULL)
+                                continue;
+                        if (sgp->part[n]->nr_sects == 0)
+                                continue;
+                        printk("  %02x%02x %10llu %s\n",
+                                sgp->major, n + 1 + sgp->first_minor,
+                                (unsigned long long)sgp->part[n]->nr_sects >> 1,
+                                disk_name(sgp, n + 1, buf));
+                } /* partition subloop */
+        } /* Block device loop */
+
+        mutex_unlock(&block_subsys_lock);
+        return;
+}
+
 #ifdef CONFIG_PROC_FS
 /* iterator */
 static void *part_start(struct seq_file *part, loff_t *pos)
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 2c65da7cabb2..f589559cf070 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -413,6 +413,7 @@ char *disk_name (struct gendisk *hd, int part, char *buf);
 extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
 extern void add_partition(struct gendisk *, int, sector_t, sector_t, int);
 extern void delete_partition(struct gendisk *, int);
+extern void printk_all_partitions(void);
 
 extern struct gendisk *alloc_disk_node(int minors, int node_id);
 extern struct gendisk *alloc_disk(int minors);
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 3f57ed4599d6..46fe407fb03e 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -7,6 +7,7 @@
 #include <linux/root_dev.h>
 #include <linux/security.h>
 #include <linux/delay.h>
+#include <linux/genhd.h>
 #include <linux/mount.h>
 #include <linux/device.h>
 #include <linux/init.h>
@@ -308,17 +309,21 @@ retry:
                 /*
                  * Allow the user to distinguish between failed sys_open
                  * and bad superblock on root device.
+                 * and give them a list of the available devices
                  */
 #ifdef CONFIG_BLOCK
                 __bdevname(ROOT_DEV, b);
 #endif
                 printk("VFS: Cannot open root device \"%s\" or %s\n",
                                 root_device_name, b);
-                printk("Please append a correct \"root=\" boot option\n");
+                printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 
+                printk_all_partitions();
                 panic("VFS: Unable to mount root fs on %s", b);
         }
 
+        printk("List of all partitions:\n");
+        printk_all_partitions();
         printk("No filesystem could mount root, tried: ");
         for (p = fs_names; *p; p += strlen(p)+1)
                 printk(" %s", p);