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    SubjectRe: [PATCH 10/16] show partitions on mount error
    Hi,


    On Apr 1 2007 22:47, Andrew Morton wrote:
    >On Sun, 1 Apr 2007 20:15:53 +0200 (MEST) Jan Engelhardt <jengelh@linux01.gwdg.de> wrote:
    >>
    >> Display all possible partitions when the root filesystem is not mounted.
    >> This helps to track spell'o's and missing drivers.
    >>
    >> +void printk_all_partitions(void)
    >
    >I made this __init.

    Seems reasonable.
    I have done some additional cleanups, see patch below.


    >It would be nice to include a sample of the resulting output for people
    >to review.

    Loaded with PXELINUX...

    LABEL l
    KERNEL bzImage
    APPEND root=/dev/foobar

    or root=/dev/sdb both produce:

    [...]
    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)

    With root=/dev/sdb, the list of possible filesystems is also displayed
    (a patch that was merged a (long)while back).


    ---

    Integrated __init annotation, and deindented the loop by one level.
    Replaces original patch.

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

    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 +215,59 @@ 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 __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.kset.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: 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>
    -
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