drivers/target/tcm_fc/tfc_io.c - kernel/msm-4.19 - Gitiles

 /*
  * Copyright (c) 2010 Cisco Systems, Inc.
  *
  * Portions based on tcm_loop_fabric_scsi.c and libfc/fc_fcp.c
  *
  * Copyright (c) 2007 Intel Corporation. All rights reserved.
  * Copyright (c) 2008 Red Hat, Inc.  All rights reserved.
  * Copyright (c) 2008 Mike Christie
  * Copyright (c) 2009 Rising Tide, Inc.
  * Copyright (c) 2009 Linux-iSCSI.org
  * Copyright (c) 2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  */

 /* XXX TBD some includes may be extraneous */

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/version.h>
 #include <generated/utsrelease.h>
 #include <linux/utsname.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/kthread.h>
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/configfs.h>
 #include <linux/ctype.h>
 #include <linux/hash.h>
 #include <asm/unaligned.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/libfc.h>
 #include <scsi/fc_encode.h>

 #include <target/target_core_base.h>
 #include <target/target_core_transport.h>
 #include <target/target_core_fabric_ops.h>
 #include <target/target_core_device.h>
 #include <target/target_core_tpg.h>
 #include <target/target_core_configfs.h>
 #include <target/target_core_base.h>
 #include <target/configfs_macros.h>

 #include "tcm_fc.h"

 /*
  * Deliver read data back to initiator.
  * XXX TBD handle resource problems later.
  */
 int ft_queue_data_in(struct se_cmd *se_cmd)
 {
 	struct ft_cmd *cmd = container_of(se_cmd, struct ft_cmd, se_cmd);
 	struct se_transport_task *task;
 	struct fc_frame *fp = NULL;
 	struct fc_exch *ep;
 	struct fc_lport *lport;
 	struct se_mem *mem;
 	size_t remaining;
 	u32 f_ctl = FC_FC_EX_CTX | FC_FC_REL_OFF;
 	u32 mem_off;
 	u32 fh_off = 0;
 	u32 frame_off = 0;
 	size_t frame_len = 0;
 	size_t mem_len;
 	size_t tlen;
 	size_t off_in_page;
 	struct page *page;
 	int use_sg;
 	int error;
 	void *page_addr;
 	void *from;
 	void *to = NULL;

 	ep = fc_seq_exch(cmd->seq);
 	lport = ep->lp;
 	cmd->seq = lport->tt.seq_start_next(cmd->seq);

 	task = T_TASK(se_cmd);
 	BUG_ON(!task);
 	remaining = se_cmd->data_length;

 	/*
 	 * Setup to use first mem list entry if any.
 	 */
 	if (task->t_tasks_se_num) {
 		mem = list_first_entry(task->t_mem_list,
 			 struct se_mem, se_list);
 		mem_len = mem->se_len;
 		mem_off = mem->se_off;
 		page = mem->se_page;
 	} else {
 		mem = NULL;
 		mem_len = remaining;
 		mem_off = 0;
 		page = NULL;
 	}

 	/* no scatter/gather in skb for odd word length due to fc_seq_send() */
 	use_sg = !(remaining % 4);

 	while (remaining) {
 		if (!mem_len) {
 			BUG_ON(!mem);
 			mem = list_entry(mem->se_list.next,
 				struct se_mem, se_list);
 			mem_len = min((size_t)mem->se_len, remaining);
 			mem_off = mem->se_off;
 			page = mem->se_page;
 		}
 		if (!frame_len) {
 			/*
 			 * If lport's has capability of Large Send Offload LSO)
 			 * , then allow 'frame_len' to be as big as 'lso_max'
 			 * if indicated transfer length is >= lport->lso_max
 			 */
 			frame_len = (lport->seq_offload) ? lport->lso_max :
 							  cmd->sess->max_frame;
 			frame_len = min(frame_len, remaining);
 			fp = fc_frame_alloc(lport, use_sg ? 0 : frame_len);
 			if (!fp)
 				return -ENOMEM;
 			to = fc_frame_payload_get(fp, 0);
 			fh_off = frame_off;
 			frame_off += frame_len;
 			/*
 			 * Setup the frame's max payload which is used by base
 			 * driver to indicate HW about max frame size, so that
 			 * HW can do fragmentation appropriately based on
 			 * "gso_max_size" of underline netdev.
 			 */
 			fr_max_payload(fp) = cmd->sess->max_frame;
 		}
 		tlen = min(mem_len, frame_len);

 		if (use_sg) {
 			if (!mem) {
 				BUG_ON(!task->t_task_buf);
 				page_addr = task->t_task_buf + mem_off;
 				/*
 				 * In this case, offset is 'offset_in_page' of
 				 * (t_task_buf + mem_off) instead of 'mem_off'.
 				 */
 				off_in_page = offset_in_page(page_addr);
 				page = virt_to_page(page_addr);
 				tlen = min(tlen, PAGE_SIZE - off_in_page);
 			} else
 				off_in_page = mem_off;
 			BUG_ON(!page);
 			get_page(page);
 			skb_fill_page_desc(fp_skb(fp),
 					   skb_shinfo(fp_skb(fp))->nr_frags,
 					   page, off_in_page, tlen);
 			fr_len(fp) += tlen;
 			fp_skb(fp)->data_len += tlen;
 			fp_skb(fp)->truesize +=
 					PAGE_SIZE << compound_order(page);
 		} else if (mem) {
 			BUG_ON(!page);
 			from = kmap_atomic(page + (mem_off >> PAGE_SHIFT),
 					   KM_SOFTIRQ0);
 			page_addr = from;
 			from += mem_off & ~PAGE_MASK;
 			tlen = min(tlen, (size_t)(PAGE_SIZE -
 						(mem_off & ~PAGE_MASK)));
 			memcpy(to, from, tlen);
 			kunmap_atomic(page_addr, KM_SOFTIRQ0);
 			to += tlen;
 		} else {
 			from = task->t_task_buf + mem_off;
 			memcpy(to, from, tlen);
 			to += tlen;
 		}

 		mem_off += tlen;
 		mem_len -= tlen;
 		frame_len -= tlen;
 		remaining -= tlen;

 		if (frame_len &&
 		    (skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN))
 			continue;
 		if (!remaining)
 			f_ctl |= FC_FC_END_SEQ;
 		fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
 			       FC_TYPE_FCP, f_ctl, fh_off);
 		error = lport->tt.seq_send(lport, cmd->seq, fp);
 		if (error) {
 			/* XXX For now, initiator will retry */
 			if (printk_ratelimit())
 				printk(KERN_ERR "%s: Failed to send frame %p, "
 						"xid <0x%x>, remaining <0x%x>, "
 						"lso_max <0x%x>\n",
 						__func__, fp, ep->xid,
 						remaining, lport->lso_max);
 		}
 	}
 	return ft_queue_status(se_cmd);
 }

 /*
  * Receive write data frame.
  */
 void ft_recv_write_data(struct ft_cmd *cmd, struct fc_frame *fp)
 {
 	struct se_cmd *se_cmd = &cmd->se_cmd;
 	struct fc_seq *seq = cmd->seq;
 	struct fc_exch *ep;
 	struct fc_lport *lport;
 	struct se_transport_task *task;
 	struct fc_frame_header *fh;
 	struct se_mem *mem;
 	u32 mem_off;
 	u32 rel_off;
 	size_t frame_len;
 	size_t mem_len;
 	size_t tlen;
 	struct page *page;
 	void *page_addr;
 	void *from;
 	void *to;
 	u32 f_ctl;
 	void *buf;

 	task = T_TASK(se_cmd);
 	BUG_ON(!task);

 	fh = fc_frame_header_get(fp);
 	if (!(ntoh24(fh->fh_f_ctl) & FC_FC_REL_OFF))
 		goto drop;

 	/*
 	 * Doesn't expect even single byte of payload. Payload
 	 * is expected to be copied directly to user buffers
 	 * due to DDP (Large Rx offload) feature, hence
 	 * BUG_ON if BUF is non-NULL
 	 */
 	buf = fc_frame_payload_get(fp, 1);
 	if (cmd->was_ddp_setup && buf) {
 		printk(KERN_INFO "%s: When DDP was setup, not expected to"
 				 "receive frame with payload, Payload shall be"
 				 "copied directly to buffer instead of coming "
 				 "via. legacy receive queues\n", __func__);
 		BUG_ON(buf);
 	}

 	/*
 	 * If ft_cmd indicated 'ddp_setup', in that case only the last frame
 	 * should come with 'TSI bit being set'. If 'TSI bit is not set and if
 	 * data frame appears here, means error condition. In both the cases
 	 * release the DDP context (ddp_put) and in error case, as well
 	 * initiate error recovery mechanism.
 	 */
 	ep = fc_seq_exch(seq);
 	if (cmd->was_ddp_setup) {
 		BUG_ON(!ep);
 		lport = ep->lp;
 		BUG_ON(!lport);
 	}
 	if (cmd->was_ddp_setup && ep->xid != FC_XID_UNKNOWN) {
 		f_ctl = ntoh24(fh->fh_f_ctl);
 		/*
 		 * If TSI bit set in f_ctl, means last write data frame is
 		 * received successfully where payload is posted directly
 		 * to user buffer and only the last frame's header is posted
 		 * in legacy receive queue
 		 */
 		if (f_ctl & FC_FC_SEQ_INIT) { /* TSI bit set in FC frame */
 			cmd->write_data_len = lport->tt.ddp_done(lport,
 								ep->xid);
 			goto last_frame;
 		} else {
 			/*
 			 * Updating the write_data_len may be meaningless at
 			 * this point, but just in case if required in future
 			 * for debugging or any other purpose
 			 */
 			printk(KERN_ERR "%s: Received frame with TSI bit not"
 					" being SET, dropping the frame, "
 					"cmd->sg <%p>, cmd->sg_cnt <0x%x>\n",
 					__func__, cmd->sg, cmd->sg_cnt);
 			cmd->write_data_len = lport->tt.ddp_done(lport,
 							      ep->xid);
 			lport->tt.seq_exch_abort(cmd->seq, 0);
 			goto drop;
 		}
 	}

 	rel_off = ntohl(fh->fh_parm_offset);
 	frame_len = fr_len(fp);
 	if (frame_len <= sizeof(*fh))
 		goto drop;
 	frame_len -= sizeof(*fh);
 	from = fc_frame_payload_get(fp, 0);
 	if (rel_off >= se_cmd->data_length)
 		goto drop;
 	if (frame_len + rel_off > se_cmd->data_length)
 		frame_len = se_cmd->data_length - rel_off;

 	/*
 	 * Setup to use first mem list entry if any.
 	 */
 	if (task->t_tasks_se_num) {
 		mem = list_first_entry(task->t_mem_list,
 				       struct se_mem, se_list);
 		mem_len = mem->se_len;
 		mem_off = mem->se_off;
 		page = mem->se_page;
 	} else {
 		mem = NULL;
 		page = NULL;
 		mem_off = 0;
 		mem_len = frame_len;
 	}

 	while (frame_len) {
 		if (!mem_len) {
 			BUG_ON(!mem);
 			mem = list_entry(mem->se_list.next,
 					 struct se_mem, se_list);
 			mem_len = mem->se_len;
 			mem_off = mem->se_off;
 			page = mem->se_page;
 		}
 		if (rel_off >= mem_len) {
 			rel_off -= mem_len;
 			mem_len = 0;
 			continue;
 		}
 		mem_off += rel_off;
 		mem_len -= rel_off;
 		rel_off = 0;

 		tlen = min(mem_len, frame_len);

 		if (mem) {
 			to = kmap_atomic(page + (mem_off >> PAGE_SHIFT),
 					 KM_SOFTIRQ0);
 			page_addr = to;
 			to += mem_off & ~PAGE_MASK;
 			tlen = min(tlen, (size_t)(PAGE_SIZE -
 						(mem_off & ~PAGE_MASK)));
 			memcpy(to, from, tlen);
 			kunmap_atomic(page_addr, KM_SOFTIRQ0);
 		} else {
 			to = task->t_task_buf + mem_off;
 			memcpy(to, from, tlen);
 		}
 		from += tlen;
 		frame_len -= tlen;
 		mem_off += tlen;
 		mem_len -= tlen;
 		cmd->write_data_len += tlen;
 	}
 last_frame:
 	if (cmd->write_data_len == se_cmd->data_length)
 		transport_generic_handle_data(se_cmd);
 drop:
 	fc_frame_free(fp);
 }
	/*
	* Copyright (c) 2010 Cisco Systems, Inc.
	*
	* Portions based on tcm_loop_fabric_scsi.c and libfc/fc_fcp.c
	*
	* Copyright (c) 2007 Intel Corporation. All rights reserved.
	* Copyright (c) 2008 Red Hat, Inc. All rights reserved.
	* Copyright (c) 2008 Mike Christie
	* Copyright (c) 2009 Rising Tide, Inc.
	* Copyright (c) 2009 Linux-iSCSI.org
	* Copyright (c) 2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	/* XXX TBD some includes may be extraneous */

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/version.h>
	#include <generated/utsrelease.h>
	#include <linux/utsname.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/kthread.h>
	#include <linux/types.h>
	#include <linux/string.h>
	#include <linux/configfs.h>
	#include <linux/ctype.h>
	#include <linux/hash.h>
	#include <asm/unaligned.h>
	#include <scsi/scsi.h>
	#include <scsi/scsi_host.h>
	#include <scsi/scsi_device.h>
	#include <scsi/scsi_cmnd.h>
	#include <scsi/libfc.h>
	#include <scsi/fc_encode.h>

	#include <target/target_core_base.h>
	#include <target/target_core_transport.h>
	#include <target/target_core_fabric_ops.h>
	#include <target/target_core_device.h>
	#include <target/target_core_tpg.h>
	#include <target/target_core_configfs.h>
	#include <target/target_core_base.h>
	#include <target/configfs_macros.h>

	#include "tcm_fc.h"

	/*
	* Deliver read data back to initiator.
	* XXX TBD handle resource problems later.
	*/
	int ft_queue_data_in(struct se_cmd *se_cmd)
	{
	struct ft_cmd *cmd = container_of(se_cmd, struct ft_cmd, se_cmd);
	struct se_transport_task *task;
	struct fc_frame *fp = NULL;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct se_mem *mem;
	size_t remaining;
	u32 f_ctl = FC_FC_EX_CTX \| FC_FC_REL_OFF;
	u32 mem_off;
	u32 fh_off = 0;
	u32 frame_off = 0;
	size_t frame_len = 0;
	size_t mem_len;
	size_t tlen;
	size_t off_in_page;
	struct page *page;
	int use_sg;
	int error;
	void *page_addr;
	void *from;
	void *to = NULL;

	ep = fc_seq_exch(cmd->seq);
	lport = ep->lp;
	cmd->seq = lport->tt.seq_start_next(cmd->seq);

	task = T_TASK(se_cmd);
	BUG_ON(!task);
	remaining = se_cmd->data_length;

	/*
	* Setup to use first mem list entry if any.
	*/
	if (task->t_tasks_se_num) {
	mem = list_first_entry(task->t_mem_list,
	struct se_mem, se_list);
	mem_len = mem->se_len;
	mem_off = mem->se_off;
	page = mem->se_page;
	} else {
	mem = NULL;
	mem_len = remaining;
	mem_off = 0;
	page = NULL;
	}

	/* no scatter/gather in skb for odd word length due to fc_seq_send() */
	use_sg = !(remaining % 4);

	while (remaining) {
	if (!mem_len) {
	BUG_ON(!mem);
	mem = list_entry(mem->se_list.next,
	struct se_mem, se_list);
	mem_len = min((size_t)mem->se_len, remaining);
	mem_off = mem->se_off;
	page = mem->se_page;
	}
	if (!frame_len) {
	/*
	* If lport's has capability of Large Send Offload LSO)
	* , then allow 'frame_len' to be as big as 'lso_max'
	* if indicated transfer length is >= lport->lso_max
	*/
	frame_len = (lport->seq_offload) ? lport->lso_max :
	cmd->sess->max_frame;
	frame_len = min(frame_len, remaining);
	fp = fc_frame_alloc(lport, use_sg ? 0 : frame_len);
	if (!fp)
	return -ENOMEM;
	to = fc_frame_payload_get(fp, 0);
	fh_off = frame_off;
	frame_off += frame_len;
	/*
	* Setup the frame's max payload which is used by base
	* driver to indicate HW about max frame size, so that
	* HW can do fragmentation appropriately based on
	* "gso_max_size" of underline netdev.
	*/
	fr_max_payload(fp) = cmd->sess->max_frame;
	}
	tlen = min(mem_len, frame_len);

	if (use_sg) {
	if (!mem) {
	BUG_ON(!task->t_task_buf);
	page_addr = task->t_task_buf + mem_off;
	/*
	* In this case, offset is 'offset_in_page' of
	* (t_task_buf + mem_off) instead of 'mem_off'.
	*/
	off_in_page = offset_in_page(page_addr);
	page = virt_to_page(page_addr);
	tlen = min(tlen, PAGE_SIZE - off_in_page);
	} else
	off_in_page = mem_off;
	BUG_ON(!page);
	get_page(page);
	skb_fill_page_desc(fp_skb(fp),
	skb_shinfo(fp_skb(fp))->nr_frags,
	page, off_in_page, tlen);
	fr_len(fp) += tlen;
	fp_skb(fp)->data_len += tlen;
	fp_skb(fp)->truesize +=
	PAGE_SIZE << compound_order(page);
	} else if (mem) {
	BUG_ON(!page);
	from = kmap_atomic(page + (mem_off >> PAGE_SHIFT),
	KM_SOFTIRQ0);
	page_addr = from;
	from += mem_off & ~PAGE_MASK;
	tlen = min(tlen, (size_t)(PAGE_SIZE -
	(mem_off & ~PAGE_MASK)));
	memcpy(to, from, tlen);
	kunmap_atomic(page_addr, KM_SOFTIRQ0);
	to += tlen;
	} else {
	from = task->t_task_buf + mem_off;
	memcpy(to, from, tlen);
	to += tlen;
	}

	mem_off += tlen;
	mem_len -= tlen;
	frame_len -= tlen;
	remaining -= tlen;

	if (frame_len &&
	(skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN))
	continue;
	if (!remaining)
	f_ctl \|= FC_FC_END_SEQ;
	fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
	FC_TYPE_FCP, f_ctl, fh_off);
	error = lport->tt.seq_send(lport, cmd->seq, fp);
	if (error) {
	/* XXX For now, initiator will retry */
	if (printk_ratelimit())
	printk(KERN_ERR "%s: Failed to send frame %p, "
	"xid <0x%x>, remaining <0x%x>, "
	"lso_max <0x%x>\n",
	__func__, fp, ep->xid,
	remaining, lport->lso_max);
	}
	}
	return ft_queue_status(se_cmd);
	}

	/*
	* Receive write data frame.
	*/
	void ft_recv_write_data(struct ft_cmd cmd, struct fc_frame fp)
	{
	struct se_cmd *se_cmd = &cmd->se_cmd;
	struct fc_seq *seq = cmd->seq;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct se_transport_task *task;
	struct fc_frame_header *fh;
	struct se_mem *mem;
	u32 mem_off;
	u32 rel_off;
	size_t frame_len;
	size_t mem_len;
	size_t tlen;
	struct page *page;
	void *page_addr;
	void *from;
	void *to;
	u32 f_ctl;
	void *buf;

	task = T_TASK(se_cmd);
	BUG_ON(!task);

	fh = fc_frame_header_get(fp);
	if (!(ntoh24(fh->fh_f_ctl) & FC_FC_REL_OFF))
	goto drop;

	/*
	* Doesn't expect even single byte of payload. Payload
	* is expected to be copied directly to user buffers
	* due to DDP (Large Rx offload) feature, hence
	* BUG_ON if BUF is non-NULL
	*/
	buf = fc_frame_payload_get(fp, 1);
	if (cmd->was_ddp_setup && buf) {
	printk(KERN_INFO "%s: When DDP was setup, not expected to"
	"receive frame with payload, Payload shall be"
	"copied directly to buffer instead of coming "
	"via. legacy receive queues\n", __func__);
	BUG_ON(buf);
	}

	/*
	* If ft_cmd indicated 'ddp_setup', in that case only the last frame
	* should come with 'TSI bit being set'. If 'TSI bit is not set and if
	* data frame appears here, means error condition. In both the cases
	* release the DDP context (ddp_put) and in error case, as well
	* initiate error recovery mechanism.
	*/
	ep = fc_seq_exch(seq);
	if (cmd->was_ddp_setup) {
	BUG_ON(!ep);
	lport = ep->lp;
	BUG_ON(!lport);
	}
	if (cmd->was_ddp_setup && ep->xid != FC_XID_UNKNOWN) {
	f_ctl = ntoh24(fh->fh_f_ctl);
	/*
	* If TSI bit set in f_ctl, means last write data frame is
	* received successfully where payload is posted directly
	* to user buffer and only the last frame's header is posted
	* in legacy receive queue
	*/
	if (f_ctl & FC_FC_SEQ_INIT) { /* TSI bit set in FC frame */
	cmd->write_data_len = lport->tt.ddp_done(lport,
	ep->xid);
	goto last_frame;
	} else {
	/*
	* Updating the write_data_len may be meaningless at
	* this point, but just in case if required in future
	* for debugging or any other purpose
	*/
	printk(KERN_ERR "%s: Received frame with TSI bit not"
	" being SET, dropping the frame, "
	"cmd->sg <%p>, cmd->sg_cnt <0x%x>\n",
	__func__, cmd->sg, cmd->sg_cnt);
	cmd->write_data_len = lport->tt.ddp_done(lport,
	ep->xid);
	lport->tt.seq_exch_abort(cmd->seq, 0);
	goto drop;
	}
	}

	rel_off = ntohl(fh->fh_parm_offset);
	frame_len = fr_len(fp);
	if (frame_len <= sizeof(*fh))
	goto drop;
	frame_len -= sizeof(*fh);
	from = fc_frame_payload_get(fp, 0);
	if (rel_off >= se_cmd->data_length)
	goto drop;
	if (frame_len + rel_off > se_cmd->data_length)
	frame_len = se_cmd->data_length - rel_off;

	/*
	* Setup to use first mem list entry if any.
	*/
	if (task->t_tasks_se_num) {
	mem = list_first_entry(task->t_mem_list,
	struct se_mem, se_list);
	mem_len = mem->se_len;
	mem_off = mem->se_off;
	page = mem->se_page;
	} else {
	mem = NULL;
	page = NULL;
	mem_off = 0;
	mem_len = frame_len;
	}

	while (frame_len) {
	if (!mem_len) {
	BUG_ON(!mem);
	mem = list_entry(mem->se_list.next,
	struct se_mem, se_list);
	mem_len = mem->se_len;
	mem_off = mem->se_off;
	page = mem->se_page;
	}
	if (rel_off >= mem_len) {
	rel_off -= mem_len;
	mem_len = 0;
	continue;
	}
	mem_off += rel_off;
	mem_len -= rel_off;
	rel_off = 0;

	tlen = min(mem_len, frame_len);

	if (mem) {
	to = kmap_atomic(page + (mem_off >> PAGE_SHIFT),
	KM_SOFTIRQ0);
	page_addr = to;
	to += mem_off & ~PAGE_MASK;
	tlen = min(tlen, (size_t)(PAGE_SIZE -
	(mem_off & ~PAGE_MASK)));
	memcpy(to, from, tlen);
	kunmap_atomic(page_addr, KM_SOFTIRQ0);
	} else {
	to = task->t_task_buf + mem_off;
	memcpy(to, from, tlen);
	}
	from += tlen;
	frame_len -= tlen;
	mem_off += tlen;
	mem_len -= tlen;
	cmd->write_data_len += tlen;
	}
	last_frame:
	if (cmd->write_data_len == se_cmd->data_length)
	transport_generic_handle_data(se_cmd);
	drop:
	fc_frame_free(fp);
	}