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Display all possible partitions when the root filesystem failed to mount
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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)

[[email protected]: cleanups, fix printk warnings]
Signed-off-by: Jan Engelhardt <[email protected]>
Cc: Dave Gilbert <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Dave Gilbert authored and Linus Torvalds committed May 9, 2007
1 parent 0e7d18b commit dd2a345
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Showing 3 changed files with 60 additions and 1 deletion.
53 changes: 53 additions & 0 deletions block/genhd.c
Original file line number Diff line number Diff line change
Expand Up @@ -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)
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1 change: 1 addition & 0 deletions include/linux/genhd.h
Original file line number Diff line number Diff line change
Expand Up @@ -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);
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7 changes: 6 additions & 1 deletion init/do_mounts.c
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -308,17 +309,21 @@ void __init mount_block_root(char *name, int flags)
/*
* 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);
Expand Down

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