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block: do_mounts - accept root=<non-existant partition>

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Some devices, like md, may create partitions only at first access,
so allow root= to be set to a valid non-existant partition of an
existing disk. This applies only to non-initramfs root mounting.

This fixes a regression from 2.6.24 which did allow this to happen and
broke some users machines :(

Acked-by: Neil Brown <neilb@suse.de>
Tested-by: Joao Luis Meloni Assirati <assirati@nonada.if.usp.br>
Cc: stable <stable@kernel.org>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Kay Sievers 2008-05-06 22:31:33 +02:00 committed by Greg Kroah-Hartman
parent 9604006d28
commit 30f2f0eb4b
3 changed files with 34 additions and 6 deletions
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9
block/genhd.c
View file

@ -653,7 +653,7 @@ void genhd_media_change_notify(struct gendisk *disk)
EXPORT_SYMBOL_GPL(genhd_media_change_notify);
#endif /* 0 */
dev_t blk_lookup_devt(const char *name)
dev_t blk_lookup_devt(const char *name, int part)
{
struct device *dev;
dev_t devt = MKDEV(0, 0);
@ -661,7 +661,11 @@ dev_t blk_lookup_devt(const char *name)
mutex_lock(&block_class_lock);
list_for_each_entry(dev, &block_class.devices, node) {
if (strcmp(dev->bus_id, name) == 0) {
devt = dev->devt;
struct gendisk *disk = dev_to_disk(dev);
if (part < disk->minors)
devt = MKDEV(MAJOR(dev->devt),
MINOR(dev->devt) + part);
break;
}
}
@ -669,7 +673,6 @@ dev_t blk_lookup_devt(const char *name)
return devt;
}
EXPORT_SYMBOL(blk_lookup_devt);
struct gendisk *alloc_disk(int minors)

4
include/linux/genhd.h
View file

@ -525,7 +525,7 @@ struct unixware_disklabel {
#define ADDPART_FLAG_RAID 1
#define ADDPART_FLAG_WHOLEDISK 2
extern dev_t blk_lookup_devt(const char *name);
extern dev_t blk_lookup_devt(const char *name, int part);
extern char *disk_name (struct gendisk *hd, int part, char *buf);
extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
@ -553,7 +553,7 @@ static inline struct block_device *bdget_disk(struct gendisk *disk, int index)
static inline void printk_all_partitions(void) { }
static inline dev_t blk_lookup_devt(const char *name)
static inline dev_t blk_lookup_devt(const char *name, int part)
{
dev_t devt = MKDEV(0, 0);
return devt;

27
init/do_mounts.c
View file

@ -76,6 +76,7 @@ dev_t name_to_dev_t(char *name)
char s[32];
char *p;
dev_t res = 0;
int part;
if (strncmp(name, "/dev/", 5) != 0) {
unsigned maj, min;
@ -106,7 +107,31 @@ dev_t name_to_dev_t(char *name)
for (p = s; *p; p++)
if (*p == '/')
*p = '!';
res = blk_lookup_devt(s);
res = blk_lookup_devt(s, 0);
if (res)
goto done;
/*
* try non-existant, but valid partition, which may only exist
* after revalidating the disk, like partitioned md devices
*/
while (p > s && isdigit(p[-1]))
p--;
if (p == s || !*p || *p == '0')
goto fail;
/* try disk name without <part number> */
part = simple_strtoul(p, NULL, 10);
*p = '\0';
res = blk_lookup_devt(s, part);
if (res)
goto done;
/* try disk name without p<part number> */
if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
goto fail;
p[-1] = '\0';
res = blk_lookup_devt(s, part);
if (res)
goto done;