From e96e72c45a1e78e9266dd70113b851395a440ef3 Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Tue, 19 Oct 2010 14:22:21 +0200 Subject: [SCSI] libosd: Support for scatter gather write/read commands This patch adds the Scatter-Gather (sg) API to libosd. Scatter-gather enables a write/read of multiple none-contiguous areas of an object, in a single call. The extents may overlap and/or be in any order. The Scatter-Gather list is sent to the target in what is called a "cdb continuation segment". This is yet another possible segment in the osd-out-buffer. It is unlike all other segments in that it sits before the actual "data" segment (which until now was always first), and that it is signed by itself and not part of the data buffer. This is because the cdb-continuation-segment is considered a spill-over of the CDB data, and is therefor signed under OSD_SEC_CAPKEY and higher. TODO: A new osd_finalize_request_ex version should be supplied so the @caps received on the network also contains a size parameter and can be spilled over into the "cdb continuation segment". Thanks to John Chandy for the original code, and investigations. And the implementation of SG support in the osd-target. Original-coded-by: John Chandy Signed-off-by: Boaz Harrosh Signed-off-by: James Bottomley --- include/scsi/osd_initiator.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'include/scsi/osd_initiator.h') diff --git a/include/scsi/osd_initiator.h b/include/scsi/osd_initiator.h index a8f3701..169a5dc 100644 --- a/include/scsi/osd_initiator.h +++ b/include/scsi/osd_initiator.h @@ -137,7 +137,7 @@ struct osd_request { void *buff; unsigned alloc_size; /* 0 here means: don't call kfree */ unsigned total_bytes; - } set_attr, enc_get_attr, get_attr; + } cdb_cont, set_attr, enc_get_attr, get_attr; struct _osd_io_info { struct bio *bio; @@ -448,6 +448,13 @@ void osd_req_read(struct osd_request *or, int osd_req_read_kern(struct osd_request *or, const struct osd_obj_id *obj, u64 offset, void *buff, u64 len); +/* Scatter/Gather write/read commands */ +int osd_req_write_sg(struct osd_request *or, + const struct osd_obj_id *obj, struct bio *bio, + const struct osd_sg_entry *sglist, unsigned numentries); +int osd_req_read_sg(struct osd_request *or, + const struct osd_obj_id *obj, struct bio *bio, + const struct osd_sg_entry *sglist, unsigned numentries); /* * Root/Partition/Collection/Object Attributes commands */ -- cgit v1.1