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Subject[PATCH] virtio_blk: Add help function to format mass of disks
Date
The current virtio block's naming algorithm just supports 18278
(26^3 + 26^2 + 26) disks. If there are mass of virtio blocks,
there will be disks with the same name.

Based on commit 3e1a7ff8a0a7b948f2684930166954f9e8e776fe, I add
function "virtblk_name_format()" for virtio block to support mass
of disks naming.

Signed-off-by: Ren Mingxin <renmx@cn.fujitsu.com>
---
drivers/block/virtio_blk.c | 38 ++++++++++++++++++++++++++------------
1 files changed, 26 insertions(+), 12 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c4a60ba..86516c8 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -374,6 +374,31 @@ 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 +467,7 @@ static int __devinit virtblk_probe(struct virtio_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);
--
1.7.1


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