[SCSI] tcm_fc: Adding FC_FC4 provider (tcm_fc) for FCoE target (TCM - target core) support

This is a comprehensive patch for FC-FC4 provider. tcm_fc is a FC-FC4
provider which glues target core (TCM) with Fiber channel library
(libfc). tcm_fc uses existing FC4 provider hooks from Fiber channel
library. This Fiber channel library is used by FCoE (transport - FC
over Ethernet) protocol driver as well.

Combination of modules such as Fiber channel library, tcm_fc, TCM
target core, and FCoE protocol driver enables functional FCoE target.

This patch includes initial commit for tcm_fc plus additional
enhancement, bug fixes.

This tcm_fc module essentially contains 3 entry points such as "prli",
"prlo", "recv".  When process login request (ELS_PRLI) request is
received, Fiber channel library (libfc) module calls passive providers
(FC-FC4, tcm_fc) (if any registered) "prli" function. Likewise when
LOGO request is received, "prlo" function of passive provider is
invoked by libfc.  For all other request (e.g. any read/write, task
management, LUN inquiry commands), "recv" function of passiver
provider is invoked by libfc. Those passive providers "prli, prlo,
recv" functions interact with TCM target core for requested operation.

This module was primarily developed by "Joe Eykholt" and there were
significant contributions from the people listed under signed-off.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Kiran Patil <kiran.patil@intel.com>

Acked-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 374 insertions, 0 deletions

diff --git a/drivers/target/tcm_fc/tfc_io.c b/drivers/target/tcm_fc/tfc_io.c
new file mode 100644
index 000000000000..4c3c0efbe13f
--- /dev/null
+++ b/drivers/target/tcm_fc/tfc_io.c
@@ -0,0 +1,374 @@
+/*
+ * 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);
+}