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Subject[PATCH] xen-blkfront: properly name all devices
- devices beyond xvdzz didn't get proper names assigned at all
- extended devices with minors not representable within the kernel's
major/minor bit split spilled into foreign majors

Signed-off-by: Jan Beulich <jbeulich@suse.com>

---
drivers/block/xen-blkfront.c | 40 ++++++++++++++++++++++------------------
1 file changed, 22 insertions(+), 18 deletions(-)
--- 3.4-rc1/drivers/block/xen-blkfront.c
+++ 3.4-rc1-xen-blkfront-all-devices/drivers/block/xen-blkfront.c
@@ -528,6 +528,14 @@ static int xen_translate_vdev(int vdevic
return 0;
}

+static char *encode_disk_name(char *ptr, unsigned int n)
+{
+ if (n >= 26)
+ ptr = encode_disk_name(ptr, n / 26 - 1);
+ *ptr = 'a' + n % 26;
+ return ptr + 1;
+}
+
static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
struct blkfront_info *info,
u16 vdisk_info, u16 sector_size)
@@ -538,6 +546,7 @@ static int xlvbd_alloc_gendisk(blkif_sec
unsigned int offset;
int minor;
int nr_parts;
+ char *ptr;

BUG_ON(info->gd != NULL);
BUG_ON(info->rq != NULL);
@@ -562,7 +571,11 @@ static int xlvbd_alloc_gendisk(blkif_sec
"emulated IDE disks,\n\t choose an xvd device name"
"from xvde on\n", info->vdevice);
}
- err = -ENODEV;
+ if (minor >> MINORBITS) {
+ pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
+ info->vdevice, minor);
+ return -ENODEV;
+ }

if ((minor % nr_parts) == 0)
nr_minors = nr_parts;
@@ -576,23 +589,14 @@ static int xlvbd_alloc_gendisk(blkif_sec
if (gd == NULL)
goto release;

- if (nr_minors > 1) {
- if (offset < 26)
- sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
- else
- sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
- 'a' + ((offset / 26)-1), 'a' + (offset % 26));
- } else {
- if (offset < 26)
- sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
- 'a' + offset,
- minor & (nr_parts - 1));
- else
- sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
- 'a' + ((offset / 26) - 1),
- 'a' + (offset % 26),
- minor & (nr_parts - 1));
- }
+ strcpy(gd->disk_name, DEV_NAME);
+ ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
+ BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
+ if (nr_minors > 1)
+ *ptr = 0;
+ else
+ snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
+ "%d", minor & (nr_parts - 1));

gd->major = XENVBD_MAJOR;
gd->first_minor = minor;




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