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Commit 58682874 authored by Robert Love's avatar Robert Love Committed by James Bottomley
Browse files

[SCSI] libfc: Add routine to copy data from a buffer to a SG list 



When handling the multi-frame responses of fc pass-thru requests,
a code segment similar to fc_fcp_recv_data (routine to receive
inbound SCSI data) is used in the response handler. This patch
is to add a routine, called fc_copy_buffer_to_sglist(), to handle
the common function of copying data from a buffer to a scatter-
gather list in order to avoid code duplication.

Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
parent 07aac328

drivers/scsi/libfc/fc_fcp.c

+10 −46
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp) 
	size_t len;

	void *buf;

	struct scatterlist *sg;

	size_t remaining;

	u32 nents;



	fh = fc_frame_header_get(fp);

	offset = ntohl(fh->fh_parm_offset);
@@ -347,55 +347,19 @@ static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp) 
	if (offset != fsp->xfer_len)

		fsp->state |= FC_SRB_DISCONTIG;



	crc = 0;

	if (fr_flags(fp) & FCPHF_CRC_UNCHECKED)

		crc = crc32(~0, (u8 *) fh, sizeof(*fh));



	sg = scsi_sglist(sc);

	remaining = len;



	while (remaining > 0 && sg) {

		size_t off;

		void *page_addr;

		size_t sg_bytes;



		if (offset >= sg->length) {

			offset -= sg->length;

			sg = sg_next(sg);

			continue;

		}

		sg_bytes = min(remaining, sg->length - offset);



		/*

		 * The scatterlist item may be bigger than PAGE_SIZE,

		 * but we are limited to mapping PAGE_SIZE at a time.

		 */

		off = offset + sg->offset;

		sg_bytes = min(sg_bytes, (size_t)

			       (PAGE_SIZE - (off & ~PAGE_MASK)));

		page_addr = kmap_atomic(sg_page(sg) + (off >> PAGE_SHIFT),

					KM_SOFTIRQ0);

		if (!page_addr)

			break;		/* XXX panic? */



		if (fr_flags(fp) & FCPHF_CRC_UNCHECKED)

			crc = crc32(crc, buf, sg_bytes);

		memcpy((char *)page_addr + (off & ~PAGE_MASK), buf,

		       sg_bytes);



		kunmap_atomic(page_addr, KM_SOFTIRQ0);

		buf += sg_bytes;

		offset += sg_bytes;

		remaining -= sg_bytes;

		copy_len += sg_bytes;

	}

	nents = scsi_sg_count(sc);



	if (fr_flags(fp) & FCPHF_CRC_UNCHECKED) {

	if (!(fr_flags(fp) & FCPHF_CRC_UNCHECKED)) {

		copy_len = fc_copy_buffer_to_sglist(buf, len, sg, &nents,

						    &offset, KM_SOFTIRQ0, NULL);

	} else {

		crc = crc32(~0, (u8 *) fh, sizeof(*fh));

		copy_len = fc_copy_buffer_to_sglist(buf, len, sg, &nents,

						    &offset, KM_SOFTIRQ0, &crc);

		buf = fc_frame_payload_get(fp, 0);

		if (len % 4) {

		if (len % 4)

			crc = crc32(crc, buf + len, 4 - (len % 4));

			len += 4 - (len % 4);

		}



		if (~crc != le32_to_cpu(fr_crc(fp))) {

crc_err:

drivers/scsi/libfc/fc_libfc.c

+60 −0
Original line number Diff line number Diff line
@@ -72,3 +72,63 @@ static void __exit libfc_exit(void) 
	fc_destroy_rport();

}

module_exit(libfc_exit);



/**

 * fc_copy_buffer_to_sglist() - This routine copies the data of a buffer

 *                              into a scatter-gather list (SG list).

 *

 * @buf: pointer to the data buffer.

 * @len: the byte-length of the data buffer.

 * @sg: pointer to the pointer of the SG list.

 * @nents: pointer to the remaining number of entries in the SG list.

 * @offset: pointer to the current offset in the SG list.

 * @km_type: dedicated page table slot type for kmap_atomic.

 * @crc: pointer to the 32-bit crc value.

 *       If crc is NULL, CRC is not calculated.

 */

u32 fc_copy_buffer_to_sglist(void *buf, size_t len,

			     struct scatterlist *sg,

			     u32 *nents, size_t *offset,

			     enum km_type km_type, u32 *crc)

{

	size_t remaining = len;

	u32 copy_len = 0;



	while (remaining > 0 && sg) {

		size_t off, sg_bytes;

		void *page_addr;



		if (*offset >= sg->length) {

			/*

			 * Check for end and drop resources

			 * from the last iteration.

			 */

			if (!(*nents))

				break;

			--(*nents);

			*offset -= sg->length;

			sg = sg_next(sg);

			continue;

		}

		sg_bytes = min(remaining, sg->length - *offset);



		/*

		 * The scatterlist item may be bigger than PAGE_SIZE,

		 * but we are limited to mapping PAGE_SIZE at a time.

		 */

		off = *offset + sg->offset;

		sg_bytes = min(sg_bytes,

			       (size_t)(PAGE_SIZE - (off & ~PAGE_MASK)));

		page_addr = kmap_atomic(sg_page(sg) + (off >> PAGE_SHIFT),

					km_type);

		if (crc)

			*crc = crc32(*crc, buf, sg_bytes);

		memcpy((char *)page_addr + (off & ~PAGE_MASK), buf, sg_bytes);

		kunmap_atomic(page_addr, km_type);

		buf += sg_bytes;

		*offset += sg_bytes;

		remaining -= sg_bytes;

		copy_len += sg_bytes;

	}

	return copy_len;

}

drivers/scsi/libfc/fc_libfc.h

+8 −0
Original line number Diff line number Diff line
@@ -101,4 +101,12 @@ void fc_destroy_fcp(void); 
 */

const char *fc_els_resp_type(struct fc_frame *);



/*

 * Copies a buffer into an sg list

 */

u32 fc_copy_buffer_to_sglist(void *buf, size_t len,

			     struct scatterlist *sg,

			     u32 *nents, size_t *offset,

			     enum km_type km_type, u32 *crc);



#endif /* _FC_LIBFC_H_ */