block: Expand Xen blkfront for > 16 xvd
Until recently, the maximum number of xvd block devices you could attach to a Xen domU was 16. This limitation turned out to be problematic for some users, so it was expanded to handle a much larger number of disks. However, this requires a couple of changes in the way that blkfront scans for disks. This functionality is already present in the Xen linux-2.6.18-xen.hg tree; the attached patch adds this functionality to the mainline xen-blkfront implementation. I successfully tested it on a 2.6.25 tree, and build tested it on 2.6.27-rc3. Signed-off-by: Chris Lalancette <clalance@redhat.com> Acked-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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@ -105,15 +105,17 @@ static DEFINE_SPINLOCK(blkif_io_lock);
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#define GRANT_INVALID_REF 0
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#define PARTS_PER_DISK 16
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#define PARTS_PER_EXT_DISK 256
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#define BLKIF_MAJOR(dev) ((dev)>>8)
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#define BLKIF_MINOR(dev) ((dev) & 0xff)
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#define DEV_NAME "xvd" /* name in /dev */
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#define EXT_SHIFT 28
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#define EXTENDED (1<<EXT_SHIFT)
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#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
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#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
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/* Information about our VBDs. */
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#define MAX_VBDS 64
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static LIST_HEAD(vbds_list);
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#define DEV_NAME "xvd" /* name in /dev */
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static int get_id_from_freelist(struct blkfront_info *info)
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{
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@ -386,31 +388,60 @@ static int xlvbd_barrier(struct blkfront_info *info)
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}
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static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity,
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int vdevice, u16 vdisk_info, u16 sector_size,
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struct blkfront_info *info)
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static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
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struct blkfront_info *info,
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u16 vdisk_info, u16 sector_size)
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{
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struct gendisk *gd;
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int nr_minors = 1;
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int err = -ENODEV;
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unsigned int offset;
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int minor;
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int nr_parts;
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BUG_ON(info->gd != NULL);
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BUG_ON(info->rq != NULL);
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if ((minor % PARTS_PER_DISK) == 0)
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nr_minors = PARTS_PER_DISK;
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if ((info->vdevice>>EXT_SHIFT) > 1) {
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/* this is above the extended range; something is wrong */
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printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
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return -ENODEV;
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}
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if (!VDEV_IS_EXTENDED(info->vdevice)) {
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minor = BLKIF_MINOR(info->vdevice);
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nr_parts = PARTS_PER_DISK;
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} else {
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minor = BLKIF_MINOR_EXT(info->vdevice);
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nr_parts = PARTS_PER_EXT_DISK;
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}
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if ((minor % nr_parts) == 0)
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nr_minors = nr_parts;
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gd = alloc_disk(nr_minors);
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if (gd == NULL)
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goto out;
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if (nr_minors > 1)
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sprintf(gd->disk_name, "%s%c", DEV_NAME,
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'a' + minor / PARTS_PER_DISK);
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offset = minor / nr_parts;
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if (nr_minors > 1) {
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if (offset < 26)
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sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
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else
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sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
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'a' + ((offset / 26)-1), 'a' + (offset % 26));
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} else {
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if (offset < 26)
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sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
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'a' + minor / PARTS_PER_DISK,
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minor % PARTS_PER_DISK);
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'a' + offset,
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minor & (nr_parts - 1));
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else
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sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
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'a' + ((offset / 26) - 1),
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'a' + (offset % 26),
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minor & (nr_parts - 1));
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}
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gd->major = XENVBD_MAJOR;
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gd->first_minor = minor;
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@ -698,10 +729,15 @@ static int blkfront_probe(struct xenbus_device *dev,
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/* FIXME: Use dynamic device id if this is not set. */
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err = xenbus_scanf(XBT_NIL, dev->nodename,
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"virtual-device", "%i", &vdevice);
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if (err != 1) {
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/* go looking in the extended area instead */
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err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
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"%i", &vdevice);
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if (err != 1) {
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xenbus_dev_fatal(dev, err, "reading virtual-device");
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return err;
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}
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}
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info = kzalloc(sizeof(*info), GFP_KERNEL);
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if (!info) {
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@ -861,9 +897,7 @@ static void blkfront_connect(struct blkfront_info *info)
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if (err)
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info->feature_barrier = 0;
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err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice),
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sectors, info->vdevice,
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binfo, sector_size, info);
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err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
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if (err) {
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xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
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info->xbdev->otherend);
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