Re: [PATCH] virtio_blk: add helper function to support mass of disks naming
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-03-28 10:58:23
Also in:
kvm, linux-scsi, lkml
On Wed, Mar 28, 2012 at 02:54:43PM +0800, Ren Mingxin wrote:
Hi, The current virtblk's naming algorithm just supports 26^3 disks. If there are mass of virtblks(exceeding 26^3), there will be disks with the same name. According to "sd_format_disk_name()", I add function "virtblk_name_format()" for virtblk to support mass of disks. Signed-off-by: Ren Mingxin <redacted>
Nod. This is basically what 3e1a7ff8a0a7b948f2684930166954f9e8e776fe did. Except, maybe we should move this function into block core instead of duplicating it? Where would be a good place to put it? Jens, care to comment?
quoted hunk
--- virtio_blk.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-)diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index c4a60ba..07b8bf9 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c@@ -374,6 +374,30 @@ static int init_vq(struct virtio_blk *vblk) return err; } +static int virtblk_name_format(char *prefix, int index, char *buf,int buflen) +{ + const int base = 'z' - 'a' + 1; + char *begin = buf + strlen(prefix); + char *begin = buf + strlen(prefix); + char *end = buf + buflen; + char *p; + int unit; + + p = end - 1; + *p = '\0'; + unit = base; + do { + if (p == begin) + return -EINVAL; + *--p = 'a' + (index % unit); + index = (index / unit) - 1; + } while (index >= 0); + + memmove(begin, p, end - p); + memcpy(buf, prefix, strlen(prefix)); + + return 0; +} + static int __devinit virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk;@@ -442,18 +466,7 @@ static int __devinit virtblk_probe(structvirtio_device *vdev) q->queuedata = vblk; - if (index < 26) { - sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); - } else if (index < (26 + 1) * 26) { - sprintf(vblk->disk->disk_name, "vd%c%c", - 'a' + index / 26 - 1, 'a' + index % 26); - } else { - const unsigned int m1 = (index / 26 - 1) / 26 - 1; - const unsigned int m2 = (index / 26 - 1) % 26; - const unsigned int m3 = index % 26; - sprintf(vblk->disk->disk_name, "vd%c%c%c", - 'a' + m1, 'a' + m2, 'a' + m3); - } + virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN); vblk->disk->major = major; vblk->disk->first_minor = index_to_minor(index);