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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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