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Commit 4977c825 authored by Boaz Harrosh's avatar Boaz Harrosh Committed by James Bottomley
Browse files

[SCSI] libosd: osd_req_read_sg, optimize the single entry case 



Since sg-read is a bidi operation, it is a gain to convert
a single sg entry into a regular read. Better do this in the
generic layer then force each caller to do so.

Signed-off-by: default avatarBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
parent 1e34c838

drivers/scsi/osd/osd_initiator.c

+16 −4
Original line number Original line Diff line number Diff line
@@ -1005,11 +1005,23 @@ int osd_req_read_sg(struct osd_request *or, 
	const struct osd_sg_entry *sglist, unsigned numentries)

	const struct osd_sg_entry *sglist, unsigned numentries)

{

{

	u64 len;

	u64 len;

	int ret = _add_sg_continuation_descriptor(or, sglist, numentries, &len);

	u64 off;

	int ret;





	if (numentries > 1) {

		off = 0;

		ret = _add_sg_continuation_descriptor(or, sglist, numentries,

						      &len);

		if (ret)

		if (ret)

			return ret;

			return ret;

	osd_req_read(or, obj, 0, bio, len);

	} else {

		/* Optimize the case of single segment, read_sg is a

		 * bidi operation.

		 */

		len = sglist->len;

		off = sglist->offset;

	}

	osd_req_read(or, obj, off, bio, len);





	return 0;

	return 0;

}

}