Display all possible partitions when the root filesystem failed to mount
Dave Gilbert [Wed, 9 May 2007 09:33:24 +0000 (02:33 -0700)]
Display all possible partitions when the root filesystem is not mounted.
This helps to track spell'o's and missing drivers.

Updated to work with newer kernels.

Example output:

VFS: Cannot open root device "foobar" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
0800    8388608 sda driver: sd
  0801     192748 sda1
  0802    8193150 sda2
0810    4194304 sdb driver: sd
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

[akpm@linux-foundation.org: cleanups, fix printk warnings]
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Cc: Dave Gilbert <linux@treblig.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

block/genhd.c
include/linux/genhd.h
init/do_mounts.c

index b566444..93a2cf6 100644 (file)
@@ -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)
index 2c65da7..f589559 100644 (file)
@@ -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);
index 3f57ed4..46fe407 100644 (file)
@@ -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);