Cc'ing scsi mailing list (and Christoph, please speak up now,
or forever hold your peace ;-)
On Mar. 11, 2008, 21:31 +0200, Fred Isaman <iisaman@xxxxxxxxxxxxxx> wrote:
> Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxxxxxx>
> ---
> drivers/scsi/hosts.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 24271a8..64f2847 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -48,10 +48,11 @@ static void scsi_host_cls_release(struct class_device *class_dev)
> put_device(&class_to_shost(class_dev)->shost_gendev);
> }
>
> -static struct class shost_class = {
> +struct class shost_class = {
> .name = "scsi_host",
> .release = scsi_host_cls_release,
> };
> +EXPORT_SYMBOL(shost_class);
>
> /**
> * scsi_host_set_state - Take the given host through the host
This calls for a layering violation.
To fill-in more context, here's an excerpt from the next patch,
showing how you use shost_class to scan all scsi disks:
+/* Walk the list of scsi_devices. Add disks that can be opened and claimed
+ * to the device list
+ */
+static int
+nfs4_blk_add_scsi_disk(struct Scsi_Host *shost,
+ int index, struct list_head *dlist)
+{
+ static char *claim_ptr = "I belong to pnfs block driver";
+ struct block_device *bdev;
+ struct gendisk *gd;
+ struct scsi_device *sdev;
+ unsigned int major, minor, ret = 0;
+ dev_t dev;
+
+ dprintk("%s enter \n", __func__);
+ if (index >= MAX_VOLS) {
+ dprintk("%s MAX_VOLS hit\n", __func__);
+ return -ENOSPC;
+ }
+ dprintk("%s 1 \n", __func__);
+ index--;
+ shost_for_each_device(sdev, shost) {
+ dprintk("%s 2\n", __func__);
+ /* Need to do this check before bumping index */
+ if (sdev->type != TYPE_DISK)
+ continue;
+ dprintk("%s 3 index %d \n", __func__, index);
+ if (++index >= MAX_VOLS) {
+ scsi_device_put(sdev);
+ break;
+ }
+ major = (!(index >> 4) ? SCSI_DISK0_MAJOR :
+ SCSI_DISK1_MAJOR-1 + (index >> 4));
+ minor = ((index << 4) & 255);
+
+ dprintk("%s SCSI device %d:%d \n", __func__, major, minor);
+
+ dev = MKDEV(major, minor);
+ bdev = nfs4_blkdev_get(dev);
+ if (!bdev) {
+ dprintk("%s: failed to open device %d:%d\n",
+ __func__, major, minor);
+ continue;
+ }
+ gd = bdev->bd_disk;
+
+ dprintk("%s 4\n", __func__);
+
+ if (bd_claim(bdev, claim_ptr)) {
+ dprintk("%s: failed to claim device %d:%d\n",
+ __func__, gd->major, gd->first_minor);
+ blkdev_put(bdev);
+ continue;
+ }
+
+ ret = alloc_add_disk(bdev, dlist);
+ if (ret < 0)
+ goto out_err;
+ dprintk("%s ADDED DEVICE capacity %ld, bd_block_size %d\n",
+ __func__,
+ (unsigned long)gd->capacity,
+ bdev->bd_block_size);
+
+ }
+ index++;
+ dprintk("%s returns index %d \n", __func__, index);
+ return index;
+
+out_err:
+ dprintk("%s Can't add disk to list. ERROR: %d\n", __func__, ret);
+ nfs4_blkdev_put(bdev);
+ return ret;
+}
+
+/*
+ * Create a temporary list of all SCSI disks host can see, and that have not
+ * yet been claimed.
+ * shost_class: list of all registered scsi_hosts
+ * returns -errno on error, and #of devices found on success.
+ * XXX Loosely emulate scsi_host_lookup from scsi/host.c
+*/
+int nfs4_blk_create_scsi_disk_list(struct list_head *dlist)
+{
+ struct class *class = &shost_class;
+ struct class_device *cdev;
+ struct Scsi_Host *shost;
+ int ret = 0, index = 0;
+
+ dprintk("%s enter\n", __func__);
+
+ down(&class->sem);
+ list_for_each_entry(cdev, &class->children, node) {
+ dprintk("%s 1\n", __func__);
+ shost = class_to_shost(cdev);
+ ret = nfs4_blk_add_scsi_disk(shost, index, dlist);
+ dprintk("%s 2 ret %d\n", __func__, ret);
+ if (ret < 0)
+ goto out;
+ index = ret;
+ }
+out:
+ up(&class->sem);
+ return ret;
+}
My question is how should a proper API between the scsi layer and
the block layout driver look like?
Can you list your requirements, e.g.:
- scanning all available devices,
- discovering new devices on the fly
- getting notified for new devices?
Benny
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