[SCSI] libiscsi_tcp: support padding offload
[linux-2.6.git] / drivers / scsi / libiscsi_tcp.c
1 /*
2  * iSCSI over TCP/IP Data-Path lib
3  *
4  * Copyright (C) 2004 Dmitry Yusupov
5  * Copyright (C) 2004 Alex Aizman
6  * Copyright (C) 2005 - 2006 Mike Christie
7  * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
8  * maintained by open-iscsi@googlegroups.com
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published
12  * by the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * General Public License for more details.
19  *
20  * See the file COPYING included with this distribution for more details.
21  *
22  * Credits:
23  *      Christoph Hellwig
24  *      FUJITA Tomonori
25  *      Arne Redlich
26  *      Zhenyu Wang
27  */
28
29 #include <linux/types.h>
30 #include <linux/list.h>
31 #include <linux/inet.h>
32 #include <linux/file.h>
33 #include <linux/blkdev.h>
34 #include <linux/crypto.h>
35 #include <linux/delay.h>
36 #include <linux/kfifo.h>
37 #include <linux/scatterlist.h>
38 #include <net/tcp.h>
39 #include <scsi/scsi_cmnd.h>
40 #include <scsi/scsi_device.h>
41 #include <scsi/scsi_host.h>
42 #include <scsi/scsi.h>
43 #include <scsi/scsi_transport_iscsi.h>
44
45 #include "iscsi_tcp.h"
46
47 MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
48               "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
49               "Alex Aizman <itn780@yahoo.com>");
50 MODULE_DESCRIPTION("iSCSI/TCP data-path");
51 MODULE_LICENSE("GPL");
52 #undef DEBUG_TCP
53
54 #ifdef DEBUG_TCP
55 #define debug_tcp(fmt...) printk(KERN_INFO "tcp: " fmt)
56 #else
57 #define debug_tcp(fmt...)
58 #endif
59
60 static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
61                                    struct iscsi_segment *segment);
62
63 /*
64  * Scatterlist handling: inside the iscsi_segment, we
65  * remember an index into the scatterlist, and set data/size
66  * to the current scatterlist entry. For highmem pages, we
67  * kmap as needed.
68  *
69  * Note that the page is unmapped when we return from
70  * TCP's data_ready handler, so we may end up mapping and
71  * unmapping the same page repeatedly. The whole reason
72  * for this is that we shouldn't keep the page mapped
73  * outside the softirq.
74  */
75
76 /**
77  * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
78  * @segment: the buffer object
79  * @sg: scatterlist
80  * @offset: byte offset into that sg entry
81  *
82  * This function sets up the segment so that subsequent
83  * data is copied to the indicated sg entry, at the given
84  * offset.
85  */
86 static inline void
87 iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
88                           struct scatterlist *sg, unsigned int offset)
89 {
90         segment->sg = sg;
91         segment->sg_offset = offset;
92         segment->size = min(sg->length - offset,
93                             segment->total_size - segment->total_copied);
94         segment->data = NULL;
95 }
96
97 /**
98  * iscsi_tcp_segment_map - map the current S/G page
99  * @segment: iscsi_segment
100  * @recv: 1 if called from recv path
101  *
102  * We only need to possibly kmap data if scatter lists are being used,
103  * because the iscsi passthrough and internal IO paths will never use high
104  * mem pages.
105  */
106 static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
107 {
108         struct scatterlist *sg;
109
110         if (segment->data != NULL || !segment->sg)
111                 return;
112
113         sg = segment->sg;
114         BUG_ON(segment->sg_mapped);
115         BUG_ON(sg->length == 0);
116
117         /*
118          * If the page count is greater than one it is ok to send
119          * to the network layer's zero copy send path. If not we
120          * have to go the slow sendmsg path. We always map for the
121          * recv path.
122          */
123         if (page_count(sg_page(sg)) >= 1 && !recv)
124                 return;
125
126         debug_tcp("iscsi_tcp_segment_map %s %p\n", recv ? "recv" : "xmit",
127                   segment);
128         segment->sg_mapped = kmap_atomic(sg_page(sg), KM_SOFTIRQ0);
129         segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
130 }
131
132 void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
133 {
134         debug_tcp("iscsi_tcp_segment_unmap %p\n", segment);
135
136         if (segment->sg_mapped) {
137                 debug_tcp("iscsi_tcp_segment_unmap valid\n");
138                 kunmap_atomic(segment->sg_mapped, KM_SOFTIRQ0);
139                 segment->sg_mapped = NULL;
140                 segment->data = NULL;
141         }
142 }
143 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
144
145 /*
146  * Splice the digest buffer into the buffer
147  */
148 static inline void
149 iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
150 {
151         segment->data = digest;
152         segment->digest_len = ISCSI_DIGEST_SIZE;
153         segment->total_size += ISCSI_DIGEST_SIZE;
154         segment->size = ISCSI_DIGEST_SIZE;
155         segment->copied = 0;
156         segment->sg = NULL;
157         segment->hash = NULL;
158 }
159
160 /**
161  * iscsi_tcp_segment_done - check whether the segment is complete
162  * @tcp_conn: iscsi tcp connection
163  * @segment: iscsi segment to check
164  * @recv: set to one of this is called from the recv path
165  * @copied: number of bytes copied
166  *
167  * Check if we're done receiving this segment. If the receive
168  * buffer is full but we expect more data, move on to the
169  * next entry in the scatterlist.
170  *
171  * If the amount of data we received isn't a multiple of 4,
172  * we will transparently receive the pad bytes, too.
173  *
174  * This function must be re-entrant.
175  */
176 int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
177                            struct iscsi_segment *segment, int recv,
178                            unsigned copied)
179 {
180         static unsigned char padbuf[ISCSI_PAD_LEN];
181         struct scatterlist sg;
182         unsigned int pad;
183
184         debug_tcp("copied %u %u size %u %s\n", segment->copied, copied,
185                   segment->size, recv ? "recv" : "xmit");
186         if (segment->hash && copied) {
187                 /*
188                  * If a segment is kmapd we must unmap it before sending
189                  * to the crypto layer since that will try to kmap it again.
190                  */
191                 iscsi_tcp_segment_unmap(segment);
192
193                 if (!segment->data) {
194                         sg_init_table(&sg, 1);
195                         sg_set_page(&sg, sg_page(segment->sg), copied,
196                                     segment->copied + segment->sg_offset +
197                                                         segment->sg->offset);
198                 } else
199                         sg_init_one(&sg, segment->data + segment->copied,
200                                     copied);
201                 crypto_hash_update(segment->hash, &sg, copied);
202         }
203
204         segment->copied += copied;
205         if (segment->copied < segment->size) {
206                 iscsi_tcp_segment_map(segment, recv);
207                 return 0;
208         }
209
210         segment->total_copied += segment->copied;
211         segment->copied = 0;
212         segment->size = 0;
213
214         /* Unmap the current scatterlist page, if there is one. */
215         iscsi_tcp_segment_unmap(segment);
216
217         /* Do we have more scatterlist entries? */
218         debug_tcp("total copied %u total size %u\n", segment->total_copied,
219                    segment->total_size);
220         if (segment->total_copied < segment->total_size) {
221                 /* Proceed to the next entry in the scatterlist. */
222                 iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
223                                           0);
224                 iscsi_tcp_segment_map(segment, recv);
225                 BUG_ON(segment->size == 0);
226                 return 0;
227         }
228
229         /* Do we need to handle padding? */
230         if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
231                 pad = iscsi_padding(segment->total_copied);
232                 if (pad != 0) {
233                         debug_tcp("consume %d pad bytes\n", pad);
234                         segment->total_size += pad;
235                         segment->size = pad;
236                         segment->data = padbuf;
237                         return 0;
238                 }
239         }
240
241         /*
242          * Set us up for transferring the data digest. hdr digest
243          * is completely handled in hdr done function.
244          */
245         if (segment->hash) {
246                 crypto_hash_final(segment->hash, segment->digest);
247                 iscsi_tcp_segment_splice_digest(segment,
248                                  recv ? segment->recv_digest : segment->digest);
249                 return 0;
250         }
251
252         return 1;
253 }
254 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);
255
256 /**
257  * iscsi_tcp_segment_recv - copy data to segment
258  * @tcp_conn: the iSCSI TCP connection
259  * @segment: the buffer to copy to
260  * @ptr: data pointer
261  * @len: amount of data available
262  *
263  * This function copies up to @len bytes to the
264  * given buffer, and returns the number of bytes
265  * consumed, which can actually be less than @len.
266  *
267  * If hash digest is enabled, the function will update the
268  * hash while copying.
269  * Combining these two operations doesn't buy us a lot (yet),
270  * but in the future we could implement combined copy+crc,
271  * just way we do for network layer checksums.
272  */
273 static int
274 iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
275                        struct iscsi_segment *segment, const void *ptr,
276                        unsigned int len)
277 {
278         unsigned int copy = 0, copied = 0;
279
280         while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
281                 if (copied == len) {
282                         debug_tcp("iscsi_tcp_segment_recv copied %d bytes\n",
283                                   len);
284                         break;
285                 }
286
287                 copy = min(len - copied, segment->size - segment->copied);
288                 debug_tcp("iscsi_tcp_segment_recv copying %d\n", copy);
289                 memcpy(segment->data + segment->copied, ptr + copied, copy);
290                 copied += copy;
291         }
292         return copied;
293 }
294
295 inline void
296 iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
297                       unsigned char digest[ISCSI_DIGEST_SIZE])
298 {
299         struct scatterlist sg;
300
301         sg_init_one(&sg, hdr, hdrlen);
302         crypto_hash_digest(hash, &sg, hdrlen, digest);
303 }
304 EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
305
306 static inline int
307 iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
308                       struct iscsi_segment *segment)
309 {
310         if (!segment->digest_len)
311                 return 1;
312
313         if (memcmp(segment->recv_digest, segment->digest,
314                    segment->digest_len)) {
315                 debug_scsi("digest mismatch\n");
316                 return 0;
317         }
318
319         return 1;
320 }
321
322 /*
323  * Helper function to set up segment buffer
324  */
325 static inline void
326 __iscsi_segment_init(struct iscsi_segment *segment, size_t size,
327                      iscsi_segment_done_fn_t *done, struct hash_desc *hash)
328 {
329         memset(segment, 0, sizeof(*segment));
330         segment->total_size = size;
331         segment->done = done;
332
333         if (hash) {
334                 segment->hash = hash;
335                 crypto_hash_init(hash);
336         }
337 }
338
339 inline void
340 iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
341                           size_t size, iscsi_segment_done_fn_t *done,
342                           struct hash_desc *hash)
343 {
344         __iscsi_segment_init(segment, size, done, hash);
345         segment->data = data;
346         segment->size = size;
347 }
348 EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
349
350 inline int
351 iscsi_segment_seek_sg(struct iscsi_segment *segment,
352                       struct scatterlist *sg_list, unsigned int sg_count,
353                       unsigned int offset, size_t size,
354                       iscsi_segment_done_fn_t *done, struct hash_desc *hash)
355 {
356         struct scatterlist *sg;
357         unsigned int i;
358
359         debug_scsi("iscsi_segment_seek_sg offset %u size %llu\n",
360                   offset, size);
361         __iscsi_segment_init(segment, size, done, hash);
362         for_each_sg(sg_list, sg, sg_count, i) {
363                 debug_scsi("sg %d, len %u offset %u\n", i, sg->length,
364                            sg->offset);
365                 if (offset < sg->length) {
366                         iscsi_tcp_segment_init_sg(segment, sg, offset);
367                         return 0;
368                 }
369                 offset -= sg->length;
370         }
371
372         return ISCSI_ERR_DATA_OFFSET;
373 }
374 EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);
375
376 /**
377  * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
378  * @tcp_conn: iscsi connection to prep for
379  *
380  * This function always passes NULL for the hash argument, because when this
381  * function is called we do not yet know the final size of the header and want
382  * to delay the digest processing until we know that.
383  */
384 void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
385 {
386         debug_tcp("iscsi_tcp_hdr_recv_prep(%p%s)\n", tcp_conn,
387                   tcp_conn->iscsi_conn->hdrdgst_en ? ", digest enabled" : "");
388         iscsi_segment_init_linear(&tcp_conn->in.segment,
389                                 tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
390                                 iscsi_tcp_hdr_recv_done, NULL);
391 }
392 EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
393
394 /*
395  * Handle incoming reply to any other type of command
396  */
397 static int
398 iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
399                          struct iscsi_segment *segment)
400 {
401         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
402         int rc = 0;
403
404         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
405                 return ISCSI_ERR_DATA_DGST;
406
407         rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
408                         conn->data, tcp_conn->in.datalen);
409         if (rc)
410                 return rc;
411
412         iscsi_tcp_hdr_recv_prep(tcp_conn);
413         return 0;
414 }
415
416 static void
417 iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
418 {
419         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
420         struct hash_desc *rx_hash = NULL;
421
422         if (conn->datadgst_en &
423             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
424                 rx_hash = tcp_conn->rx_hash;
425
426         iscsi_segment_init_linear(&tcp_conn->in.segment,
427                                 conn->data, tcp_conn->in.datalen,
428                                 iscsi_tcp_data_recv_done, rx_hash);
429 }
430
431 /**
432  * iscsi_tcp_cleanup_task - free tcp_task resources
433  * @task: iscsi task
434  *
435  * must be called with session lock
436  */
437 void iscsi_tcp_cleanup_task(struct iscsi_task *task)
438 {
439         struct iscsi_tcp_task *tcp_task = task->dd_data;
440         struct iscsi_r2t_info *r2t;
441
442         /* nothing to do for mgmt or pending tasks */
443         if (!task->sc || task->state == ISCSI_TASK_PENDING)
444                 return;
445
446         /* flush task's r2t queues */
447         while (__kfifo_get(tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
448                 __kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
449                             sizeof(void*));
450                 debug_scsi("iscsi_tcp_cleanup_task pending r2t dropped\n");
451         }
452
453         r2t = tcp_task->r2t;
454         if (r2t != NULL) {
455                 __kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
456                             sizeof(void*));
457                 tcp_task->r2t = NULL;
458         }
459 }
460 EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
461
462 /**
463  * iscsi_tcp_data_in - SCSI Data-In Response processing
464  * @conn: iscsi connection
465  * @task: scsi command task
466  */
467 static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
468 {
469         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
470         struct iscsi_tcp_task *tcp_task = task->dd_data;
471         struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
472         int datasn = be32_to_cpu(rhdr->datasn);
473         unsigned total_in_length = scsi_in(task->sc)->length;
474
475         iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);
476         if (tcp_conn->in.datalen == 0)
477                 return 0;
478
479         if (tcp_task->exp_datasn != datasn) {
480                 debug_tcp("%s: task->exp_datasn(%d) != rhdr->datasn(%d)\n",
481                           __func__, tcp_task->exp_datasn, datasn);
482                 return ISCSI_ERR_DATASN;
483         }
484
485         tcp_task->exp_datasn++;
486
487         tcp_task->data_offset = be32_to_cpu(rhdr->offset);
488         if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
489                 debug_tcp("%s: data_offset(%d) + data_len(%d) > total_length_in(%d)\n",
490                           __func__, tcp_task->data_offset,
491                           tcp_conn->in.datalen, total_in_length);
492                 return ISCSI_ERR_DATA_OFFSET;
493         }
494
495         conn->datain_pdus_cnt++;
496         return 0;
497 }
498
499 /**
500  * iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
501  * @conn: iscsi connection
502  * @task: scsi command task
503  */
504 static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
505 {
506         struct iscsi_session *session = conn->session;
507         struct iscsi_tcp_task *tcp_task = task->dd_data;
508         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
509         struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
510         struct iscsi_r2t_info *r2t;
511         int r2tsn = be32_to_cpu(rhdr->r2tsn);
512         int rc;
513
514         if (tcp_conn->in.datalen) {
515                 iscsi_conn_printk(KERN_ERR, conn,
516                                   "invalid R2t with datalen %d\n",
517                                   tcp_conn->in.datalen);
518                 return ISCSI_ERR_DATALEN;
519         }
520
521         if (tcp_task->exp_datasn != r2tsn){
522                 debug_tcp("%s: task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
523                           __func__, tcp_task->exp_datasn, r2tsn);
524                 return ISCSI_ERR_R2TSN;
525         }
526
527         /* fill-in new R2T associated with the task */
528         iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
529
530         if (!task->sc || session->state != ISCSI_STATE_LOGGED_IN) {
531                 iscsi_conn_printk(KERN_INFO, conn,
532                                   "dropping R2T itt %d in recovery.\n",
533                                   task->itt);
534                 return 0;
535         }
536
537         rc = __kfifo_get(tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
538         if (!rc) {
539                 iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
540                                   "Target has sent more R2Ts than it "
541                                   "negotiated for or driver has has leaked.\n");
542                 return ISCSI_ERR_PROTO;
543         }
544
545         r2t->exp_statsn = rhdr->statsn;
546         r2t->data_length = be32_to_cpu(rhdr->data_length);
547         if (r2t->data_length == 0) {
548                 iscsi_conn_printk(KERN_ERR, conn,
549                                   "invalid R2T with zero data len\n");
550                 __kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
551                             sizeof(void*));
552                 return ISCSI_ERR_DATALEN;
553         }
554
555         if (r2t->data_length > session->max_burst)
556                 debug_scsi("invalid R2T with data len %u and max burst %u."
557                            "Attempting to execute request.\n",
558                             r2t->data_length, session->max_burst);
559
560         r2t->data_offset = be32_to_cpu(rhdr->data_offset);
561         if (r2t->data_offset + r2t->data_length > scsi_out(task->sc)->length) {
562                 iscsi_conn_printk(KERN_ERR, conn,
563                                   "invalid R2T with data len %u at offset %u "
564                                   "and total length %d\n", r2t->data_length,
565                                   r2t->data_offset, scsi_out(task->sc)->length);
566                 __kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
567                             sizeof(void*));
568                 return ISCSI_ERR_DATALEN;
569         }
570
571         r2t->ttt = rhdr->ttt; /* no flip */
572         r2t->datasn = 0;
573         r2t->sent = 0;
574
575         tcp_task->exp_datasn = r2tsn + 1;
576         __kfifo_put(tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
577         conn->r2t_pdus_cnt++;
578
579         iscsi_requeue_task(task);
580         return 0;
581 }
582
583 /*
584  * Handle incoming reply to DataIn command
585  */
586 static int
587 iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
588                           struct iscsi_segment *segment)
589 {
590         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
591         struct iscsi_hdr *hdr = tcp_conn->in.hdr;
592         int rc;
593
594         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
595                 return ISCSI_ERR_DATA_DGST;
596
597         /* check for non-exceptional status */
598         if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
599                 rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
600                 if (rc)
601                         return rc;
602         }
603
604         iscsi_tcp_hdr_recv_prep(tcp_conn);
605         return 0;
606 }
607
608 /**
609  * iscsi_tcp_hdr_dissect - process PDU header
610  * @conn: iSCSI connection
611  * @hdr: PDU header
612  *
613  * This function analyzes the header of the PDU received,
614  * and performs several sanity checks. If the PDU is accompanied
615  * by data, the receive buffer is set up to copy the incoming data
616  * to the correct location.
617  */
618 static int
619 iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
620 {
621         int rc = 0, opcode, ahslen;
622         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
623         struct iscsi_task *task;
624
625         /* verify PDU length */
626         tcp_conn->in.datalen = ntoh24(hdr->dlength);
627         if (tcp_conn->in.datalen > conn->max_recv_dlength) {
628                 iscsi_conn_printk(KERN_ERR, conn,
629                                   "iscsi_tcp: datalen %d > %d\n",
630                                   tcp_conn->in.datalen, conn->max_recv_dlength);
631                 return ISCSI_ERR_DATALEN;
632         }
633
634         /* Additional header segments. So far, we don't
635          * process additional headers.
636          */
637         ahslen = hdr->hlength << 2;
638
639         opcode = hdr->opcode & ISCSI_OPCODE_MASK;
640         /* verify itt (itt encoding: age+cid+itt) */
641         rc = iscsi_verify_itt(conn, hdr->itt);
642         if (rc)
643                 return rc;
644
645         debug_tcp("opcode 0x%x ahslen %d datalen %d\n",
646                   opcode, ahslen, tcp_conn->in.datalen);
647
648         switch(opcode) {
649         case ISCSI_OP_SCSI_DATA_IN:
650                 spin_lock(&conn->session->lock);
651                 task = iscsi_itt_to_ctask(conn, hdr->itt);
652                 if (!task)
653                         rc = ISCSI_ERR_BAD_ITT;
654                 else
655                         rc = iscsi_tcp_data_in(conn, task);
656                 if (rc) {
657                         spin_unlock(&conn->session->lock);
658                         break;
659                 }
660
661                 if (tcp_conn->in.datalen) {
662                         struct iscsi_tcp_task *tcp_task = task->dd_data;
663                         struct hash_desc *rx_hash = NULL;
664                         struct scsi_data_buffer *sdb = scsi_in(task->sc);
665
666                         /*
667                          * Setup copy of Data-In into the Scsi_Cmnd
668                          * Scatterlist case:
669                          * We set up the iscsi_segment to point to the next
670                          * scatterlist entry to copy to. As we go along,
671                          * we move on to the next scatterlist entry and
672                          * update the digest per-entry.
673                          */
674                         if (conn->datadgst_en &&
675                             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
676                                 rx_hash = tcp_conn->rx_hash;
677
678                         debug_tcp("iscsi_tcp_begin_data_in(%p, offset=%d, "
679                                   "datalen=%d)\n", tcp_conn,
680                                   tcp_task->data_offset,
681                                   tcp_conn->in.datalen);
682                         rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
683                                                    sdb->table.sgl,
684                                                    sdb->table.nents,
685                                                    tcp_task->data_offset,
686                                                    tcp_conn->in.datalen,
687                                                    iscsi_tcp_process_data_in,
688                                                    rx_hash);
689                         spin_unlock(&conn->session->lock);
690                         return rc;
691                 }
692                 rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
693                 spin_unlock(&conn->session->lock);
694                 break;
695         case ISCSI_OP_SCSI_CMD_RSP:
696                 if (tcp_conn->in.datalen) {
697                         iscsi_tcp_data_recv_prep(tcp_conn);
698                         return 0;
699                 }
700                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
701                 break;
702         case ISCSI_OP_R2T:
703                 spin_lock(&conn->session->lock);
704                 task = iscsi_itt_to_ctask(conn, hdr->itt);
705                 if (!task)
706                         rc = ISCSI_ERR_BAD_ITT;
707                 else if (ahslen)
708                         rc = ISCSI_ERR_AHSLEN;
709                 else if (task->sc->sc_data_direction == DMA_TO_DEVICE)
710                         rc = iscsi_tcp_r2t_rsp(conn, task);
711                 else
712                         rc = ISCSI_ERR_PROTO;
713                 spin_unlock(&conn->session->lock);
714                 break;
715         case ISCSI_OP_LOGIN_RSP:
716         case ISCSI_OP_TEXT_RSP:
717         case ISCSI_OP_REJECT:
718         case ISCSI_OP_ASYNC_EVENT:
719                 /*
720                  * It is possible that we could get a PDU with a buffer larger
721                  * than 8K, but there are no targets that currently do this.
722                  * For now we fail until we find a vendor that needs it
723                  */
724                 if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
725                         iscsi_conn_printk(KERN_ERR, conn,
726                                           "iscsi_tcp: received buffer of "
727                                           "len %u but conn buffer is only %u "
728                                           "(opcode %0x)\n",
729                                           tcp_conn->in.datalen,
730                                           ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
731                         rc = ISCSI_ERR_PROTO;
732                         break;
733                 }
734
735                 /* If there's data coming in with the response,
736                  * receive it to the connection's buffer.
737                  */
738                 if (tcp_conn->in.datalen) {
739                         iscsi_tcp_data_recv_prep(tcp_conn);
740                         return 0;
741                 }
742         /* fall through */
743         case ISCSI_OP_LOGOUT_RSP:
744         case ISCSI_OP_NOOP_IN:
745         case ISCSI_OP_SCSI_TMFUNC_RSP:
746                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
747                 break;
748         default:
749                 rc = ISCSI_ERR_BAD_OPCODE;
750                 break;
751         }
752
753         if (rc == 0) {
754                 /* Anything that comes with data should have
755                  * been handled above. */
756                 if (tcp_conn->in.datalen)
757                         return ISCSI_ERR_PROTO;
758                 iscsi_tcp_hdr_recv_prep(tcp_conn);
759         }
760
761         return rc;
762 }
763
764 /**
765  * iscsi_tcp_hdr_recv_done - process PDU header
766  *
767  * This is the callback invoked when the PDU header has
768  * been received. If the header is followed by additional
769  * header segments, we go back for more data.
770  */
771 static int
772 iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
773                         struct iscsi_segment *segment)
774 {
775         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
776         struct iscsi_hdr *hdr;
777
778         /* Check if there are additional header segments
779          * *prior* to computing the digest, because we
780          * may need to go back to the caller for more.
781          */
782         hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
783         if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
784                 /* Bump the header length - the caller will
785                  * just loop around and get the AHS for us, and
786                  * call again. */
787                 unsigned int ahslen = hdr->hlength << 2;
788
789                 /* Make sure we don't overflow */
790                 if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
791                         return ISCSI_ERR_AHSLEN;
792
793                 segment->total_size += ahslen;
794                 segment->size += ahslen;
795                 return 0;
796         }
797
798         /* We're done processing the header. See if we're doing
799          * header digests; if so, set up the recv_digest buffer
800          * and go back for more. */
801         if (conn->hdrdgst_en &&
802             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
803                 if (segment->digest_len == 0) {
804                         /*
805                          * Even if we offload the digest processing we
806                          * splice it in so we can increment the skb/segment
807                          * counters in preparation for the data segment.
808                          */
809                         iscsi_tcp_segment_splice_digest(segment,
810                                                         segment->recv_digest);
811                         return 0;
812                 }
813
814                 iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
815                                       segment->total_copied - ISCSI_DIGEST_SIZE,
816                                       segment->digest);
817
818                 if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
819                         return ISCSI_ERR_HDR_DGST;
820         }
821
822         tcp_conn->in.hdr = hdr;
823         return iscsi_tcp_hdr_dissect(conn, hdr);
824 }
825
826 /**
827  * iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
828  * @tcp_conn: iscsi tcp conn
829  *
830  * returns non zero if we are currently processing or setup to process
831  * a header.
832  */
833 inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
834 {
835         return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
836 }
837 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);
838
839 /**
840  * iscsi_tcp_recv_skb - Process skb
841  * @conn: iscsi connection
842  * @skb: network buffer with header and/or data segment
843  * @offset: offset in skb
844  * @offload: bool indicating if transfer was offloaded
845  *
846  * Will return status of transfer in status. And will return
847  * number of bytes copied.
848  */
849 int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
850                        unsigned int offset, bool offloaded, int *status)
851 {
852         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
853         struct iscsi_segment *segment = &tcp_conn->in.segment;
854         struct skb_seq_state seq;
855         unsigned int consumed = 0;
856         int rc = 0;
857
858         debug_tcp("in %d bytes\n", skb->len - offset);
859
860         if (unlikely(conn->suspend_rx)) {
861                 debug_tcp("conn %d Rx suspended!\n", conn->id);
862                 *status = ISCSI_TCP_SUSPENDED;
863                 return 0;
864         }
865
866         if (offloaded) {
867                 segment->total_copied = segment->total_size;
868                 goto segment_done;
869         }
870
871         skb_prepare_seq_read(skb, offset, skb->len, &seq);
872         while (1) {
873                 unsigned int avail;
874                 const u8 *ptr;
875
876                 avail = skb_seq_read(consumed, &ptr, &seq);
877                 if (avail == 0) {
878                         debug_tcp("no more data avail. Consumed %d\n",
879                                   consumed);
880                         *status = ISCSI_TCP_SKB_DONE;
881                         skb_abort_seq_read(&seq);
882                         goto skb_done;
883                 }
884                 BUG_ON(segment->copied >= segment->size);
885
886                 debug_tcp("skb %p ptr=%p avail=%u\n", skb, ptr, avail);
887                 rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
888                 BUG_ON(rc == 0);
889                 consumed += rc;
890
891                 if (segment->total_copied >= segment->total_size) {
892                         skb_abort_seq_read(&seq);
893                         goto segment_done;
894                 }
895         }
896
897 segment_done:
898         *status = ISCSI_TCP_SEGMENT_DONE;
899         debug_tcp("segment done\n");
900         rc = segment->done(tcp_conn, segment);
901         if (rc != 0) {
902                 *status = ISCSI_TCP_CONN_ERR;
903                 debug_tcp("Error receiving PDU, errno=%d\n", rc);
904                 iscsi_conn_failure(conn, rc);
905                 return 0;
906         }
907         /* The done() functions sets up the next segment. */
908
909 skb_done:
910         conn->rxdata_octets += consumed;
911         return consumed;
912 }
913 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
914
915 /**
916  * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
917  * @conn: iscsi connection
918  * @task: scsi command task
919  * @sc: scsi command
920  */
921 int iscsi_tcp_task_init(struct iscsi_task *task)
922 {
923         struct iscsi_tcp_task *tcp_task = task->dd_data;
924         struct iscsi_conn *conn = task->conn;
925         struct scsi_cmnd *sc = task->sc;
926         int err;
927
928         if (!sc) {
929                 /*
930                  * mgmt tasks do not have a scatterlist since they come
931                  * in from the iscsi interface.
932                  */
933                 debug_scsi("mtask deq [cid %d itt 0x%x]\n", conn->id,
934                            task->itt);
935
936                 return conn->session->tt->init_pdu(task, 0, task->data_count);
937         }
938
939         BUG_ON(__kfifo_len(tcp_task->r2tqueue));
940         tcp_task->exp_datasn = 0;
941
942         /* Prepare PDU, optionally w/ immediate data */
943         debug_scsi("task deq [cid %d itt 0x%x imm %d unsol %d]\n",
944                     conn->id, task->itt, task->imm_count,
945                     task->unsol_r2t.data_length);
946
947         err = conn->session->tt->init_pdu(task, 0, task->imm_count);
948         if (err)
949                 return err;
950         task->imm_count = 0;
951         return 0;
952 }
953 EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
954
955 static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
956 {
957         struct iscsi_session *session = task->conn->session;
958         struct iscsi_tcp_task *tcp_task = task->dd_data;
959         struct iscsi_r2t_info *r2t = NULL;
960
961         if (iscsi_task_has_unsol_data(task))
962                 r2t = &task->unsol_r2t;
963         else {
964                 spin_lock_bh(&session->lock);
965                 if (tcp_task->r2t) {
966                         r2t = tcp_task->r2t;
967                         /* Continue with this R2T? */
968                         if (r2t->data_length <= r2t->sent) {
969                                 debug_scsi("  done with r2t %p\n", r2t);
970                                 __kfifo_put(tcp_task->r2tpool.queue,
971                                             (void *)&tcp_task->r2t,
972                                             sizeof(void *));
973                                 tcp_task->r2t = r2t = NULL;
974                         }
975                 }
976
977                 if (r2t == NULL) {
978                         __kfifo_get(tcp_task->r2tqueue,
979                                     (void *)&tcp_task->r2t, sizeof(void *));
980                         r2t = tcp_task->r2t;
981                 }
982                 spin_unlock_bh(&session->lock);
983         }
984
985         return r2t;
986 }
987
988 /**
989  * iscsi_tcp_task_xmit - xmit normal PDU task
990  * @task: iscsi command task
991  *
992  * We're expected to return 0 when everything was transmitted succesfully,
993  * -EAGAIN if there's still data in the queue, or != 0 for any other kind
994  * of error.
995  */
996 int iscsi_tcp_task_xmit(struct iscsi_task *task)
997 {
998         struct iscsi_conn *conn = task->conn;
999         struct iscsi_session *session = conn->session;
1000         struct iscsi_r2t_info *r2t;
1001         int rc = 0;
1002
1003 flush:
1004         /* Flush any pending data first. */
1005         rc = session->tt->xmit_pdu(task);
1006         if (rc < 0)
1007                 return rc;
1008
1009         /* mgmt command */
1010         if (!task->sc) {
1011                 if (task->hdr->itt == RESERVED_ITT)
1012                         iscsi_put_task(task);
1013                 return 0;
1014         }
1015
1016         /* Are we done already? */
1017         if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1018                 return 0;
1019
1020         r2t = iscsi_tcp_get_curr_r2t(task);
1021         if (r2t == NULL) {
1022                 /* Waiting for more R2Ts to arrive. */
1023                 debug_tcp("no R2Ts yet\n");
1024                 return 0;
1025         }
1026
1027         rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1028         if (rc)
1029                 return rc;
1030         iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1031
1032         debug_scsi("sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1033                    r2t, r2t->datasn - 1, task->hdr->itt,
1034                    r2t->data_offset + r2t->sent, r2t->data_count);
1035
1036         rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1037                                          r2t->data_count);
1038         if (rc)
1039                 return rc;
1040         r2t->sent += r2t->data_count;
1041         goto flush;
1042 }
1043 EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1044
1045 struct iscsi_cls_conn *
1046 iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1047                       uint32_t conn_idx)
1048
1049 {
1050         struct iscsi_conn *conn;
1051         struct iscsi_cls_conn *cls_conn;
1052         struct iscsi_tcp_conn *tcp_conn;
1053
1054         cls_conn = iscsi_conn_setup(cls_session, sizeof(*tcp_conn), conn_idx);
1055         if (!cls_conn)
1056                 return NULL;
1057         conn = cls_conn->dd_data;
1058         /*
1059          * due to strange issues with iser these are not set
1060          * in iscsi_conn_setup
1061          */
1062         conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1063
1064         tcp_conn = conn->dd_data;
1065         tcp_conn->iscsi_conn = conn;
1066
1067         tcp_conn->dd_data = kzalloc(dd_data_size, GFP_KERNEL);
1068         if (!tcp_conn->dd_data) {
1069                 iscsi_conn_teardown(cls_conn);
1070                 return NULL;
1071         }
1072         return cls_conn;
1073 }
1074 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1075
1076 void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1077 {
1078         struct iscsi_conn *conn = cls_conn->dd_data;
1079         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
1080
1081         kfree(tcp_conn->dd_data);
1082         iscsi_conn_teardown(cls_conn);
1083 }
1084 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1085
1086 int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1087 {
1088         int i;
1089         int cmd_i;
1090
1091         /*
1092          * initialize per-task: R2T pool and xmit queue
1093          */
1094         for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1095                 struct iscsi_task *task = session->cmds[cmd_i];
1096                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1097
1098                 /*
1099                  * pre-allocated x2 as much r2ts to handle race when
1100                  * target acks DataOut faster than we data_xmit() queues
1101                  * could replenish r2tqueue.
1102                  */
1103
1104                 /* R2T pool */
1105                 if (iscsi_pool_init(&tcp_task->r2tpool,
1106                                     session->max_r2t * 2, NULL,
1107                                     sizeof(struct iscsi_r2t_info))) {
1108                         goto r2t_alloc_fail;
1109                 }
1110
1111                 /* R2T xmit queue */
1112                 tcp_task->r2tqueue = kfifo_alloc(
1113                       session->max_r2t * 4 * sizeof(void*), GFP_KERNEL, NULL);
1114                 if (tcp_task->r2tqueue == ERR_PTR(-ENOMEM)) {
1115                         iscsi_pool_free(&tcp_task->r2tpool);
1116                         goto r2t_alloc_fail;
1117                 }
1118         }
1119
1120         return 0;
1121
1122 r2t_alloc_fail:
1123         for (i = 0; i < cmd_i; i++) {
1124                 struct iscsi_task *task = session->cmds[i];
1125                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1126
1127                 kfifo_free(tcp_task->r2tqueue);
1128                 iscsi_pool_free(&tcp_task->r2tpool);
1129         }
1130         return -ENOMEM;
1131 }
1132 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1133
1134 void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1135 {
1136         int i;
1137
1138         for (i = 0; i < session->cmds_max; i++) {
1139                 struct iscsi_task *task = session->cmds[i];
1140                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1141
1142                 kfifo_free(tcp_task->r2tqueue);
1143                 iscsi_pool_free(&tcp_task->r2tpool);
1144         }
1145 }
1146 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1147
1148 void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1149                               struct iscsi_stats *stats)
1150 {
1151         struct iscsi_conn *conn = cls_conn->dd_data;
1152
1153         stats->txdata_octets = conn->txdata_octets;
1154         stats->rxdata_octets = conn->rxdata_octets;
1155         stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1156         stats->dataout_pdus = conn->dataout_pdus_cnt;
1157         stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1158         stats->datain_pdus = conn->datain_pdus_cnt;
1159         stats->r2t_pdus = conn->r2t_pdus_cnt;
1160         stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1161         stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1162 }
1163 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);