osdblk: a Linux block device for OSD objects

Submitted driver exports a block device of the form /dev/osdblkX,
where X is a decimal number.

It does that by mounting a stacking block device on top
of an osd object. For example, if you create a 2G object
on an OSD device, you can then use this module to present
that 2G object as a Linux block device.

See inside patch for exact documentation.

[Sitting at linux-next helped fix proper Kconfig dependency
 for this driver, thanks to Randy Dunlap]

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index bb72ada..1d886e0 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -298,6 +298,22 @@
 
 	  If unsure, say N.
 
+config BLK_DEV_OSD
+	tristate "OSD object-as-blkdev support"
+	depends on SCSI_OSD_ULD
+	---help---
+	  Saying Y or M here will allow the exporting of a single SCSI
+	  OSD (object-based storage) object as a Linux block device.
+
+	  For example, if you create a 2G object on an OSD device,
+	  you can then use this module to present that 2G object as
+	  a Linux block device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called osdblk.
+
+	  If unsure, say N.
+
 config BLK_DEV_SX8
 	tristate "Promise SATA SX8 support"
 	depends on PCI