[PATCH 10/16] show-partitions-on-mount-error.diff

Jan Engelhardt
2007-04-01T18:16:48Z

Display all possible partitions when the root filesystem is not mounted.
This helps to track spell'o's and missing drivers.

From: David Alan Gilbert, http://lkml.org/lkml/2005/2/26/92

Updated to work with newer kernels.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>

block/genhd.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/genhd.h | 1
init/do_mounts.c | 7 +++++-
3 files changed, 61 insertions(+), 1 deletion(-)

Index: linux-2.6.21-rc5/block/genhd.c
===================================================================
--- linux-2.6.21-rc5.orig/block/genhd.c
+++ linux-2.6.21-rc5/block/genhd.c
@@ -215,6 +215,60 @@ struct gendisk *get_gendisk(dev_t dev, i
return kobj ? to_disk(kobj) : NULL;
}

+/*
+ * printk 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 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.kset.list, kobj.entry) {
+ char buf[BDEVNAME_SIZE];
+ /*
+ * Don't show empty devices or things that have been surpressed
+ */
+ if (get_capacity(sgp) &&
+ !(sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)) {
+ /*
+ * Note, unlike /proc/partitions I am showing the
+ * numbers in hex in the same format as the root=
+ * option
+ */
+ 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) &&
+ (sgp->driverfs_dev->driver)) {
+ 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])
+ 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 */
+ } /* Non 0 size, not surpressed */
+ } /* 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: linux-2.6.21-rc5/include/linux/genhd.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/genhd.h
+++ linux-2.6.21-rc5/include/linux/genhd.h
@@ -413,6 +413,7 @@ char *disk_name (struct gendisk *hd, int
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: linux-2.6.21-rc5/init/do_mounts.c
===================================================================
--- linux-2.6.21-rc5.orig/init/do_mounts.c
+++ linux-2.6.21-rc5/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>

@@ -307,17 +308,21 @@ 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);
#<EOF>