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/*
* iSCSI over TCP/IP Data-Path lib
*
* Copyright (C) 2004 Dmitry Yusupov
* Copyright (C) 2004 Alex Aizman
* Copyright (C) 2005 - 2006 Mike Christie
* Copyright (C) 2006 Red Hat, Inc. All rights reserved.
* maintained by open-iscsi@googlegroups.com
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that 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.
*
* See the file COPYING included with this distribution for more details.
*
* Credits:
* Christoph Hellwig
* FUJITA Tomonori
* Arne Redlich
* Zhenyu Wang
*/

#include <linux/types.h>
#include <linux/list.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/kfifo.h>
#include <linux/scatterlist.h>
#include <linux/module.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/scsi_transport_iscsi.h>

#include "iscsi_tcp.h"

MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
"Dmitry Yusupov <dmitry_yus@yahoo.com>, "
"Alex Aizman <itn780@yahoo.com>");
MODULE_DESCRIPTION("iSCSI/TCP data-path");
MODULE_LICENSE("GPL");

static int iscsi_dbg_libtcp;
module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
"module. Set to 1 to turn on, and zero to turn off. Default "
"is off.");

#define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...) \
do { \
if (iscsi_dbg_libtcp) \
iscsi_conn_printk(KERN_INFO, _conn, \
"%s " dbg_fmt, \
__func__, ##arg); \
} while (0);

static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment);

/*
* Scatterlist handling: inside the iscsi_segment, we
* remember an index into the scatterlist, and set data/size
* to the current scatterlist entry. For highmem pages, we
* kmap as needed.
*
* Note that the page is unmapped when we return from
* TCP's data_ready handler, so we may end up mapping and
* unmapping the same page repeatedly. The whole reason
* for this is that we shouldn't keep the page mapped
* outside the softirq.
*/

/**
* iscsi_tcp_segment_init_sg - init indicated scatterlist entry
* @segment: the buffer object
* @sg: scatterlist
* @offset: byte offset into that sg entry
*
* This function sets up the segment so that subsequent
* data is copied to the indicated sg entry, at the given
* offset.
*/
static inline void
iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
struct scatterlist *sg, unsigned int offset)
{
segment->sg = sg;
segment->sg_offset = offset;
segment->size = min(sg->length - offset,
segment->total_size - segment->total_copied);
segment->data = NULL;
}

/**
* iscsi_tcp_segment_map - map the current S/G page
* @segment: iscsi_segment
* @recv: 1 if called from recv path
*
* We only need to possibly kmap data if scatter lists are being used,
* because the iscsi passthrough and internal IO paths will never use high
* mem pages.
*/
static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
{
struct scatterlist *sg;

if (segment->data != NULL || !segment->sg)
return;

sg = segment->sg;
BUG_ON(segment->sg_mapped);
BUG_ON(sg->length == 0);

/*
* If the page count is greater than one it is ok to send
* to the network layer's zero copy send path. If not we
* have to go the slow sendmsg path. We always map for the
* recv path.
*/
if (page_count(sg_page(sg)) >= 1 && !recv)
return;

if (recv) {
segment->atomic_mapped = true;
segment->sg_mapped = kmap_atomic(sg_page(sg));
} else {
segment->atomic_mapped = false;
/* the xmit path can sleep with the page mapped so use kmap */
segment->sg_mapped = kmap(sg_page(sg));
}

segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
}

void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
{
if (segment->sg_mapped) {
if (segment->atomic_mapped)
kunmap_atomic(segment->sg_mapped);
else
kunmap(sg_page(segment->sg));
segment->sg_mapped = NULL;
segment->data = NULL;
}
}
EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);

/*
* Splice the digest buffer into the buffer
*/
static inline void
iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
{
segment->data = digest;
segment->digest_len = ISCSI_DIGEST_SIZE;
segment->total_size += ISCSI_DIGEST_SIZE;
segment->size = ISCSI_DIGEST_SIZE;
segment->copied = 0;
segment->sg = NULL;
segment->hash = NULL;
}

/**
* iscsi_tcp_segment_done - check whether the segment is complete
* @tcp_conn: iscsi tcp connection
* @segment: iscsi segment to check
* @recv: set to one of this is called from the recv path
* @copied: number of bytes copied
*
* Check if we're done receiving this segment. If the receive
* buffer is full but we expect more data, move on to the
* next entry in the scatterlist.
*
* If the amount of data we received isn't a multiple of 4,
* we will transparently receive the pad bytes, too.
*
* This function must be re-entrant.
*/
int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment, int recv,
unsigned copied)
{
struct scatterlist sg;
unsigned int pad;

ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copied %u %u size %u %s\n",
segment->copied, copied, segment->size,
recv ? "recv" : "xmit");
if (segment->hash && copied) {
/*
* If a segment is kmapd we must unmap it before sending
* to the crypto layer since that will try to kmap it again.
*/
iscsi_tcp_segment_unmap(segment);

if (!segment->data) {
sg_init_table(&sg, 1);
sg_set_page(&sg, sg_page(segment->sg), copied,
segment->copied + segment->sg_offset +
segment->sg->offset);
} else
sg_init_one(&sg, segment->data + segment->copied,
copied);
crypto_hash_update(segment->hash, &sg, copied);
}

segment->copied += copied;
if (segment->copied < segment->size) {
iscsi_tcp_segment_map(segment, recv);
return 0;
}

segment->total_copied += segment->copied;
segment->copied = 0;
segment->size = 0;

/* Unmap the current scatterlist page, if there is one. */
iscsi_tcp_segment_unmap(segment);

/* Do we have more scatterlist entries? */
ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "total copied %u total size %u\n",
segment->total_copied, segment->total_size);
if (segment->total_copied < segment->total_size) {
/* Proceed to the next entry in the scatterlist. */
iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
0);
iscsi_tcp_segment_map(segment, recv);
BUG_ON(segment->size == 0);
return 0;
}

/* Do we need to handle padding? */
if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
pad = iscsi_padding(segment->total_copied);
if (pad != 0) {
ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
"consume %d pad bytes\n", pad);
segment->total_size += pad;
segment->size = pad;
segment->data = segment->padbuf;
return 0;
}
}

/*
* Set us up for transferring the data digest. hdr digest
* is completely handled in hdr done function.
*/
if (segment->hash) {
crypto_hash_final(segment->hash, segment->digest);
iscsi_tcp_segment_splice_digest(segment,
recv ? segment->recv_digest : segment->digest);
return 0;
}

return 1;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);

/**
* iscsi_tcp_segment_recv - copy data to segment
* @tcp_conn: the iSCSI TCP connection
* @segment: the buffer to copy to
* @ptr: data pointer
* @len: amount of data available
*
* This function copies up to @len bytes to the
* given buffer, and returns the number of bytes
* consumed, which can actually be less than @len.
*
* If hash digest is enabled, the function will update the
* hash while copying.
* Combining these two operations doesn't buy us a lot (yet),
* but in the future we could implement combined copy+crc,
* just way we do for network layer checksums.
*/
static int
iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment, const void *ptr,
unsigned int len)
{
unsigned int copy = 0, copied = 0;

while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
if (copied == len) {
ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
"copied %d bytes\n", len);
break;
}

copy = min(len - copied, segment->size - segment->copied);
ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copying %d\n", copy);
memcpy(segment->data + segment->copied, ptr + copied, copy);
copied += copy;
}
return copied;
}

inline void
iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
unsigned char digest[ISCSI_DIGEST_SIZE])
{
struct scatterlist sg;

sg_init_one(&sg, hdr, hdrlen);
crypto_hash_digest(hash, &sg, hdrlen, digest);
}
EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);

static inline int
iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment)
{
if (!segment->digest_len)
return 1;

if (memcmp(segment->recv_digest, segment->digest,
segment->digest_len)) {
ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "digest mismatch\n");
return 0;
}

return 1;
}

/*
* Helper function to set up segment buffer
*/
static inline void
__iscsi_segment_init(struct iscsi_segment *segment, size_t size,
iscsi_segment_done_fn_t *done, struct hash_desc *hash)
{
memset(segment, 0, sizeof(*segment));
segment->total_size = size;
segment->done = done;

if (hash) {
segment->hash = hash;
crypto_hash_init(hash);
}
}

inline void
iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
size_t size, iscsi_segment_done_fn_t *done,
struct hash_desc *hash)
{
__iscsi_segment_init(segment, size, done, hash);
segment->data = data;
segment->size = size;
}
EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);

inline int
iscsi_segment_seek_sg(struct iscsi_segment *segment,
struct scatterlist *sg_list, unsigned int sg_count,
unsigned int offset, size_t size,
iscsi_segment_done_fn_t *done, struct hash_desc *hash)
{
struct scatterlist *sg;
unsigned int i;

__iscsi_segment_init(segment, size, done, hash);
for_each_sg(sg_list, sg, sg_count, i) {
if (offset < sg->length) {
iscsi_tcp_segment_init_sg(segment, sg, offset);
return 0;
}
offset -= sg->length;
}

return ISCSI_ERR_DATA_OFFSET;
}
EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);

/**
* iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
* @tcp_conn: iscsi connection to prep for
*
* This function always passes NULL for the hash argument, because when this
* function is called we do not yet know the final size of the header and want
* to delay the digest processing until we know that.
*/
void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
{
ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
"(%s)\n", tcp_conn->iscsi_conn->hdrdgst_en ?
"digest enabled" : "digest disabled");
iscsi_segment_init_linear(&tcp_conn->in.segment,
tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
iscsi_tcp_hdr_recv_done, NULL);
}
EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);

/*
* Handle incoming reply to any other type of command
*/
static int
iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment)
{
struct iscsi_conn *conn = tcp_conn->iscsi_conn;
int rc = 0;

if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
return ISCSI_ERR_DATA_DGST;

rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
conn->data, tcp_conn->in.datalen);
if (rc)
return rc;

iscsi_tcp_hdr_recv_prep(tcp_conn);
return 0;
}

static void
iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
{
struct iscsi_conn *conn = tcp_conn->iscsi_conn;
struct hash_desc *rx_hash = NULL;

if (conn->datadgst_en &&
!(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
rx_hash = tcp_conn->rx_hash;

iscsi_segment_init_linear(&tcp_conn->in.segment,
conn->data, tcp_conn->in.datalen,
iscsi_tcp_data_recv_done, rx_hash);
}

/**
* iscsi_tcp_cleanup_task - free tcp_task resources
* @task: iscsi task
*
* must be called with session back_lock
*/
void iscsi_tcp_cleanup_task(struct iscsi_task *task)
{
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct iscsi_r2t_info *r2t;

/* nothing to do for mgmt */
if (!task->sc)
return;

spin_lock_bh(&tcp_task->queue2pool);
/* flush task's r2t queues */
while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
}

r2t = tcp_task->r2t;
if (r2t != NULL) {
kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
tcp_task->r2t = NULL;
}
spin_unlock_bh(&tcp_task->queue2pool);
}
EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);

/**
* iscsi_tcp_data_in - SCSI Data-In Response processing
* @conn: iscsi connection
* @task: scsi command task
*/
static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
{
struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
int datasn = be32_to_cpu(rhdr->datasn);
unsigned total_in_length = scsi_in(task->sc)->length;

/*
* lib iscsi will update this in the completion handling if there
* is status.
*/
if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);

if (tcp_conn->in.datalen == 0)
return 0;

if (tcp_task->exp_datasn != datasn) {
ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->datasn(%d)"
"\n", tcp_task->exp_datasn, datasn);
return ISCSI_ERR_DATASN;
}

tcp_task->exp_datasn++;

tcp_task->data_offset = be32_to_cpu(rhdr->offset);
if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
ISCSI_DBG_TCP(conn, "data_offset(%d) + data_len(%d) > "
"total_length_in(%d)\n", tcp_task->data_offset,
tcp_conn->in.datalen, total_in_length);
return ISCSI_ERR_DATA_OFFSET;
}

conn->datain_pdus_cnt++;
return 0;
}

/**
* iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
* @conn: iscsi connection
* @task: scsi command task
*/
static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
{
struct iscsi_session *session = conn->session;
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
struct iscsi_r2t_info *r2t;
int r2tsn = be32_to_cpu(rhdr->r2tsn);
u32 data_length;
u32 data_offset;
int rc;

if (tcp_conn->in.datalen) {
iscsi_conn_printk(KERN_ERR, conn,
"invalid R2t with datalen %d\n",
tcp_conn->in.datalen);
return ISCSI_ERR_DATALEN;
}

if (tcp_task->exp_datasn != r2tsn){
ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
tcp_task->exp_datasn, r2tsn);
return ISCSI_ERR_R2TSN;
}

/* fill-in new R2T associated with the task */
iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);

if (!task->sc || session->state != ISCSI_STATE_LOGGED_IN) {
iscsi_conn_printk(KERN_INFO, conn,
"dropping R2T itt %d in recovery.\n",
task->itt);
return 0;
}

data_length = be32_to_cpu(rhdr->data_length);
if (data_length == 0) {
iscsi_conn_printk(KERN_ERR, conn,
"invalid R2T with zero data len\n");
return ISCSI_ERR_DATALEN;
}

if (data_length > session->max_burst)
ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
"burst %u. Attempting to execute request.\n",
data_length, session->max_burst);

data_offset = be32_to_cpu(rhdr->data_offset);
if (data_offset + data_length > scsi_out(task->sc)->length) {
iscsi_conn_printk(KERN_ERR, conn,
"invalid R2T with data len %u at offset %u "
"and total length %d\n", data_length,
data_offset, scsi_out(task->sc)->length);
return ISCSI_ERR_DATALEN;
}

spin_lock(&tcp_task->pool2queue);
rc = kfifo_out(&tcp_task->r2tpool.queue, (void *)&r2t, sizeof(void *));
if (!rc) {
iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
"Target has sent more R2Ts than it "
"negotiated for or driver has leaked.\n");
spin_unlock(&tcp_task->pool2queue);
return ISCSI_ERR_PROTO;
}

r2t->exp_statsn = rhdr->statsn;
r2t->data_length = data_length;
r2t->data_offset = data_offset;

r2t->ttt = rhdr->ttt; /* no flip */
r2t->datasn = 0;
r2t->sent = 0;

tcp_task->exp_datasn = r2tsn + 1;
kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
conn->r2t_pdus_cnt++;
spin_unlock(&tcp_task->pool2queue);

iscsi_requeue_task(task);
return 0;
}

/*
* Handle incoming reply to DataIn command
*/
static int
iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment)
{
struct iscsi_conn *conn = tcp_conn->iscsi_conn;
struct iscsi_hdr *hdr = tcp_conn->in.hdr;
int rc;

if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
return ISCSI_ERR_DATA_DGST;

/* check for non-exceptional status */
if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
if (rc)
return rc;
}

iscsi_tcp_hdr_recv_prep(tcp_conn);
return 0;
}

/**
* iscsi_tcp_hdr_dissect - process PDU header
* @conn: iSCSI connection
* @hdr: PDU header
*
* This function analyzes the header of the PDU received,
* and performs several sanity checks. If the PDU is accompanied
* by data, the receive buffer is set up to copy the incoming data
* to the correct location.
*/
static int
iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
{
int rc = 0, opcode, ahslen;
struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
struct iscsi_task *task;

/* verify PDU length */
tcp_conn->in.datalen = ntoh24(hdr->dlength);
if (tcp_conn->in.datalen > conn->max_recv_dlength) {
iscsi_conn_printk(KERN_ERR, conn,
"iscsi_tcp: datalen %d > %d\n",
tcp_conn->in.datalen, conn->max_recv_dlength);
return ISCSI_ERR_DATALEN;
}

/* Additional header segments. So far, we don't
* process additional headers.
*/
ahslen = hdr->hlength << 2;

opcode = hdr->opcode & ISCSI_OPCODE_MASK;
/* verify itt (itt encoding: age+cid+itt) */
rc = iscsi_verify_itt(conn, hdr->itt);
if (rc)
return rc;

ISCSI_DBG_TCP(conn, "opcode 0x%x ahslen %d datalen %d\n",
opcode, ahslen, tcp_conn->in.datalen);

switch(opcode) {
case ISCSI_OP_SCSI_DATA_IN:
spin_lock(&conn->session->back_lock);
task = iscsi_itt_to_ctask(conn, hdr->itt);
if (!task)
rc = ISCSI_ERR_BAD_ITT;
else
rc = iscsi_tcp_data_in(conn, task);
if (rc) {
spin_unlock(&conn->session->back_lock);
break;
}

if (tcp_conn->in.datalen) {
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct hash_desc *rx_hash = NULL;
struct scsi_data_buffer *sdb = scsi_in(task->sc);

/*
* Setup copy of Data-In into the Scsi_Cmnd
* Scatterlist case:
* We set up the iscsi_segment to point to the next
* scatterlist entry to copy to. As we go along,
* we move on to the next scatterlist entry and
* update the digest per-entry.
*/
if (conn->datadgst_en &&
!(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
rx_hash = tcp_conn->rx_hash;

ISCSI_DBG_TCP(conn, "iscsi_tcp_begin_data_in( "
"offset=%d, datalen=%d)\n",
tcp_task->data_offset,
tcp_conn->in.datalen);
task->last_xfer = jiffies;
rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
sdb->table.sgl,
sdb->table.nents,
tcp_task->data_offset,
tcp_conn->in.datalen,
iscsi_tcp_process_data_in,
rx_hash);
spin_unlock(&conn->session->back_lock);
return rc;
}
rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
spin_unlock(&conn->session->back_lock);
break;
case ISCSI_OP_SCSI_CMD_RSP:
if (tcp_conn->in.datalen) {
iscsi_tcp_data_recv_prep(tcp_conn);
return 0;
}
rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
break;
case ISCSI_OP_R2T:
spin_lock(&conn->session->back_lock);
task = iscsi_itt_to_ctask(conn, hdr->itt);
spin_unlock(&conn->session->back_lock);
if (!task)
rc = ISCSI_ERR_BAD_ITT;
else if (ahslen)
rc = ISCSI_ERR_AHSLEN;
else if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
task->last_xfer = jiffies;
spin_lock(&conn->session->frwd_lock);
rc = iscsi_tcp_r2t_rsp(conn, task);
spin_unlock(&conn->session->frwd_lock);
} else
rc = ISCSI_ERR_PROTO;
break;
case ISCSI_OP_LOGIN_RSP:
case ISCSI_OP_TEXT_RSP:
case ISCSI_OP_REJECT:
case ISCSI_OP_ASYNC_EVENT:
/*
* It is possible that we could get a PDU with a buffer larger
* than 8K, but there are no targets that currently do this.
* For now we fail until we find a vendor that needs it
*/
if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
iscsi_conn_printk(KERN_ERR, conn,
"iscsi_tcp: received buffer of "
"len %u but conn buffer is only %u "
"(opcode %0x)\n",
tcp_conn->in.datalen,
ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
rc = ISCSI_ERR_PROTO;
break;
}

/* If there's data coming in with the response,
* receive it to the connection's buffer.
*/
if (tcp_conn->in.datalen) {
iscsi_tcp_data_recv_prep(tcp_conn);
return 0;
}
/* fall through */
case ISCSI_OP_LOGOUT_RSP:
case ISCSI_OP_NOOP_IN:
case ISCSI_OP_SCSI_TMFUNC_RSP:
rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
break;
default:
rc = ISCSI_ERR_BAD_OPCODE;
break;
}

if (rc == 0) {
/* Anything that comes with data should have
* been handled above. */
if (tcp_conn->in.datalen)
return ISCSI_ERR_PROTO;
iscsi_tcp_hdr_recv_prep(tcp_conn);
}

return rc;
}

/**
* iscsi_tcp_hdr_recv_done - process PDU header
*
* This is the callback invoked when the PDU header has
* been received. If the header is followed by additional
* header segments, we go back for more data.
*/
static int
iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment)
{
struct iscsi_conn *conn = tcp_conn->iscsi_conn;
struct iscsi_hdr *hdr;

/* Check if there are additional header segments
* *prior* to computing the digest, because we
* may need to go back to the caller for more.
*/
hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
/* Bump the header length - the caller will
* just loop around and get the AHS for us, and
* call again. */
unsigned int ahslen = hdr->hlength << 2;

/* Make sure we don't overflow */
if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
return ISCSI_ERR_AHSLEN;

segment->total_size += ahslen;
segment->size += ahslen;
return 0;
}

/* We're done processing the header. See if we're doing
* header digests; if so, set up the recv_digest buffer
* and go back for more. */
if (conn->hdrdgst_en &&
!(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
if (segment->digest_len == 0) {
/*
* Even if we offload the digest processing we
* splice it in so we can increment the skb/segment
* counters in preparation for the data segment.
*/
iscsi_tcp_segment_splice_digest(segment,
segment->recv_digest);
return 0;
}

iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
segment->total_copied - ISCSI_DIGEST_SIZE,
segment->digest);

if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
return ISCSI_ERR_HDR_DGST;
}

tcp_conn->in.hdr = hdr;
return iscsi_tcp_hdr_dissect(conn, hdr);
}

/**
* iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
* @tcp_conn: iscsi tcp conn
*
* returns non zero if we are currently processing or setup to process
* a header.
*/
inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
{
return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);

/**
* iscsi_tcp_recv_skb - Process skb
* @conn: iscsi connection
* @skb: network buffer with header and/or data segment
* @offset: offset in skb
* @offload: bool indicating if transfer was offloaded
*
* Will return status of transfer in status. And will return
* number of bytes copied.
*/
int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
unsigned int offset, bool offloaded, int *status)
{
struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
struct iscsi_segment *segment = &tcp_conn->in.segment;
struct skb_seq_state seq;
unsigned int consumed = 0;
int rc = 0;

ISCSI_DBG_TCP(conn, "in %d bytes\n", skb->len - offset);
/*
* Update for each skb instead of pdu, because over slow networks a
* data_in's data could take a while to read in. We also want to
* account for r2ts.
*/
conn->last_recv = jiffies;

if (unlikely(conn->suspend_rx)) {
ISCSI_DBG_TCP(conn, "Rx suspended!\n");
*status = ISCSI_TCP_SUSPENDED;
return 0;
}

if (offloaded) {
segment->total_copied = segment->total_size;
goto segment_done;
}

skb_prepare_seq_read(skb, offset, skb->len, &seq);
while (1) {
unsigned int avail;
const u8 *ptr;

avail = skb_seq_read(consumed, &ptr, &seq);
if (avail == 0) {
ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
consumed);
*status = ISCSI_TCP_SKB_DONE;
goto skb_done;
}
BUG_ON(segment->copied >= segment->size);

ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
avail);
rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
BUG_ON(rc == 0);
consumed += rc;

if (segment->total_copied >= segment->total_size) {
skb_abort_seq_read(&seq);
goto segment_done;
}
}

segment_done:
*status = ISCSI_TCP_SEGMENT_DONE;
ISCSI_DBG_TCP(conn, "segment done\n");
rc = segment->done(tcp_conn, segment);
if (rc != 0) {
*status = ISCSI_TCP_CONN_ERR;
ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
iscsi_conn_failure(conn, rc);
return 0;
}
/* The done() functions sets up the next segment. */

skb_done:
conn->rxdata_octets += consumed;
return consumed;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);

/**
* iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
* @conn: iscsi connection
* @task: scsi command task
* @sc: scsi command
*/
int iscsi_tcp_task_init(struct iscsi_task *task)
{
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct iscsi_conn *conn = task->conn;
struct scsi_cmnd *sc = task->sc;
int err;

if (!sc) {
/*
* mgmt tasks do not have a scatterlist since they come
* in from the iscsi interface.
*/
ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);

return conn->session->tt->init_pdu(task, 0, task->data_count);
}

BUG_ON(kfifo_len(&tcp_task->r2tqueue));
tcp_task->exp_datasn = 0;

/* Prepare PDU, optionally w/ immediate data */
ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
task->itt, task->imm_count, task->unsol_r2t.data_length);

err = conn->session->tt->init_pdu(task, 0, task->imm_count);
if (err)
return err;
task->imm_count = 0;
return 0;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);

static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
{
struct iscsi_tcp_task *tcp_task = task->dd_data;
struct iscsi_r2t_info *r2t = NULL;

if (iscsi_task_has_unsol_data(task))
r2t = &task->unsol_r2t;
else {
spin_lock_bh(&tcp_task->queue2pool);
if (tcp_task->r2t) {
r2t = tcp_task->r2t;
/* Continue with this R2T? */
if (r2t->data_length <= r2t->sent) {
ISCSI_DBG_TCP(task->conn,
" done with r2t %p\n", r2t);
kfifo_in(&tcp_task->r2tpool.queue,
(void *)&tcp_task->r2t,
sizeof(void *));
tcp_task->r2t = r2t = NULL;
}
}

if (r2t == NULL) {
if (kfifo_out(&tcp_task->r2tqueue,
(void *)&tcp_task->r2t, sizeof(void *)) !=
sizeof(void *))
r2t = NULL;
else
r2t = tcp_task->r2t;
}
spin_unlock_bh(&tcp_task->queue2pool);
}

return r2t;
}

/**
* iscsi_tcp_task_xmit - xmit normal PDU task
* @task: iscsi command task
*
* We're expected to return 0 when everything was transmitted successfully,
* -EAGAIN if there's still data in the queue, or != 0 for any other kind
* of error.
*/
int iscsi_tcp_task_xmit(struct iscsi_task *task)
{
struct iscsi_conn *conn = task->conn;
struct iscsi_session *session = conn->session;
struct iscsi_r2t_info *r2t;
int rc = 0;

flush:
/* Flush any pending data first. */
rc = session->tt->xmit_pdu(task);
if (rc < 0)
return rc;

/* mgmt command */
if (!task->sc) {
if (task->hdr->itt == RESERVED_ITT)
iscsi_put_task(task);
return 0;
}

/* Are we done already? */
if (task->sc->sc_data_direction != DMA_TO_DEVICE)
return 0;

r2t = iscsi_tcp_get_curr_r2t(task);
if (r2t == NULL) {
/* Waiting for more R2Ts to arrive. */
ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
return 0;
}

rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
if (rc)
return rc;
iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);

ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
r2t, r2t->datasn - 1, task->hdr->itt,
r2t->data_offset + r2t->sent, r2t->data_count);

rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
r2t->data_count);
if (rc) {
iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
return rc;
}

r2t->sent += r2t->data_count;
goto flush;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);

struct iscsi_cls_conn *
iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
uint32_t conn_idx)

{
struct iscsi_conn *conn;
struct iscsi_cls_conn *cls_conn;
struct iscsi_tcp_conn *tcp_conn;

cls_conn = iscsi_conn_setup(cls_session,
sizeof(*tcp_conn) + dd_data_size, conn_idx);
if (!cls_conn)
return NULL;
conn = cls_conn->dd_data;
/*
* due to strange issues with iser these are not set
* in iscsi_conn_setup
*/
conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;

tcp_conn = conn->dd_data;
tcp_conn->iscsi_conn = conn;
tcp_conn->dd_data = conn->dd_data + sizeof(*tcp_conn);
return cls_conn;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);

void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
{
iscsi_conn_teardown(cls_conn);
}
EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);

int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
{
int i;
int cmd_i;

/*
* initialize per-task: R2T pool and xmit queue
*/
for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
struct iscsi_task *task = session->cmds[cmd_i];
struct iscsi_tcp_task *tcp_task = task->dd_data;

/*
* pre-allocated x2 as much r2ts to handle race when
* target acks DataOut faster than we data_xmit() queues
* could replenish r2tqueue.
*/

/* R2T pool */
if (iscsi_pool_init(&tcp_task->r2tpool,
session->max_r2t * 2, NULL,
sizeof(struct iscsi_r2t_info))) {
goto r2t_alloc_fail;
}

/* R2T xmit queue */
if (kfifo_alloc(&tcp_task->r2tqueue,
session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
iscsi_pool_free(&tcp_task->r2tpool);
goto r2t_alloc_fail;
}
spin_lock_init(&tcp_task->pool2queue);
spin_lock_init(&tcp_task->queue2pool);
}

return 0;

r2t_alloc_fail:
for (i = 0; i < cmd_i; i++) {
struct iscsi_task *task = session->cmds[i];
struct iscsi_tcp_task *tcp_task = task->dd_data;

kfifo_free(&tcp_task->r2tqueue);
iscsi_pool_free(&tcp_task->r2tpool);
}
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);

void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
{
int i;

for (i = 0; i < session->cmds_max; i++) {
struct iscsi_task *task = session->cmds[i];
struct iscsi_tcp_task *tcp_task = task->dd_data;

kfifo_free(&tcp_task->r2tqueue);
iscsi_pool_free(&tcp_task->r2tpool);
}
}
EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);

int iscsi_tcp_set_max_r2t(struct iscsi_conn *conn, char *buf)
{
struct iscsi_session *session = conn->session;
unsigned short r2ts = 0;

sscanf(buf, "%hu", &r2ts);
if (session->max_r2t == r2ts)
return 0;

if (!r2ts || !is_power_of_2(r2ts))
return -EINVAL;

session->max_r2t = r2ts;
iscsi_tcp_r2tpool_free(session);
return iscsi_tcp_r2tpool_alloc(session);
}
EXPORT_SYMBOL_GPL(iscsi_tcp_set_max_r2t);

void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
struct iscsi_stats *stats)
{
struct iscsi_conn *conn = cls_conn->dd_data;

stats->txdata_octets = conn->txdata_octets;
stats->rxdata_octets = conn->rxdata_octets;
stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
stats->dataout_pdus = conn->dataout_pdus_cnt;
stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
stats->datain_pdus = conn->datain_pdus_cnt;
stats->r2t_pdus = conn->r2t_pdus_cnt;
stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
}
EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);
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