[SCSI] libiscsi_tcp: use kmap in xmit path
[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/slab.h>
33 #include <linux/file.h>
34 #include <linux/blkdev.h>
35 #include <linux/crypto.h>
36 #include <linux/delay.h>
37 #include <linux/kfifo.h>
38 #include <linux/scatterlist.h>
39 #include <net/tcp.h>
40 #include <scsi/scsi_cmnd.h>
41 #include <scsi/scsi_device.h>
42 #include <scsi/scsi_host.h>
43 #include <scsi/scsi.h>
44 #include <scsi/scsi_transport_iscsi.h>
45
46 #include "iscsi_tcp.h"
47
48 MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
49               "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
50               "Alex Aizman <itn780@yahoo.com>");
51 MODULE_DESCRIPTION("iSCSI/TCP data-path");
52 MODULE_LICENSE("GPL");
53
54 static int iscsi_dbg_libtcp;
55 module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
56                    S_IRUGO | S_IWUSR);
57 MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
58                  "module. Set to 1 to turn on, and zero to turn off. Default "
59                  "is off.");
60
61 #define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...)                   \
62         do {                                                    \
63                 if (iscsi_dbg_libtcp)                           \
64                         iscsi_conn_printk(KERN_INFO, _conn,     \
65                                              "%s " dbg_fmt,     \
66                                              __func__, ##arg);  \
67         } while (0);
68
69 static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
70                                    struct iscsi_segment *segment);
71
72 /*
73  * Scatterlist handling: inside the iscsi_segment, we
74  * remember an index into the scatterlist, and set data/size
75  * to the current scatterlist entry. For highmem pages, we
76  * kmap as needed.
77  *
78  * Note that the page is unmapped when we return from
79  * TCP's data_ready handler, so we may end up mapping and
80  * unmapping the same page repeatedly. The whole reason
81  * for this is that we shouldn't keep the page mapped
82  * outside the softirq.
83  */
84
85 /**
86  * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
87  * @segment: the buffer object
88  * @sg: scatterlist
89  * @offset: byte offset into that sg entry
90  *
91  * This function sets up the segment so that subsequent
92  * data is copied to the indicated sg entry, at the given
93  * offset.
94  */
95 static inline void
96 iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
97                           struct scatterlist *sg, unsigned int offset)
98 {
99         segment->sg = sg;
100         segment->sg_offset = offset;
101         segment->size = min(sg->length - offset,
102                             segment->total_size - segment->total_copied);
103         segment->data = NULL;
104 }
105
106 /**
107  * iscsi_tcp_segment_map - map the current S/G page
108  * @segment: iscsi_segment
109  * @recv: 1 if called from recv path
110  *
111  * We only need to possibly kmap data if scatter lists are being used,
112  * because the iscsi passthrough and internal IO paths will never use high
113  * mem pages.
114  */
115 static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
116 {
117         struct scatterlist *sg;
118
119         if (segment->data != NULL || !segment->sg)
120                 return;
121
122         sg = segment->sg;
123         BUG_ON(segment->sg_mapped);
124         BUG_ON(sg->length == 0);
125
126         /*
127          * If the page count is greater than one it is ok to send
128          * to the network layer's zero copy send path. If not we
129          * have to go the slow sendmsg path. We always map for the
130          * recv path.
131          */
132         if (page_count(sg_page(sg)) >= 1 && !recv)
133                 return;
134
135         if (recv) {
136                 segment->atomic_mapped = true;
137                 segment->sg_mapped = kmap_atomic(sg_page(sg), KM_SOFTIRQ0);
138         } else {
139                 segment->atomic_mapped = false;
140                 /* the xmit path can sleep with the page mapped so use kmap */
141                 segment->sg_mapped = kmap(sg_page(sg));
142         }
143
144         segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
145 }
146
147 void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
148 {
149         if (segment->sg_mapped) {
150                 if (segment->atomic_mapped)
151                         kunmap_atomic(segment->sg_mapped, KM_SOFTIRQ0);
152                 else
153                         kunmap(sg_page(segment->sg));
154                 segment->sg_mapped = NULL;
155                 segment->data = NULL;
156         }
157 }
158 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
159
160 /*
161  * Splice the digest buffer into the buffer
162  */
163 static inline void
164 iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
165 {
166         segment->data = digest;
167         segment->digest_len = ISCSI_DIGEST_SIZE;
168         segment->total_size += ISCSI_DIGEST_SIZE;
169         segment->size = ISCSI_DIGEST_SIZE;
170         segment->copied = 0;
171         segment->sg = NULL;
172         segment->hash = NULL;
173 }
174
175 /**
176  * iscsi_tcp_segment_done - check whether the segment is complete
177  * @tcp_conn: iscsi tcp connection
178  * @segment: iscsi segment to check
179  * @recv: set to one of this is called from the recv path
180  * @copied: number of bytes copied
181  *
182  * Check if we're done receiving this segment. If the receive
183  * buffer is full but we expect more data, move on to the
184  * next entry in the scatterlist.
185  *
186  * If the amount of data we received isn't a multiple of 4,
187  * we will transparently receive the pad bytes, too.
188  *
189  * This function must be re-entrant.
190  */
191 int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
192                            struct iscsi_segment *segment, int recv,
193                            unsigned copied)
194 {
195         struct scatterlist sg;
196         unsigned int pad;
197
198         ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copied %u %u size %u %s\n",
199                       segment->copied, copied, segment->size,
200                       recv ? "recv" : "xmit");
201         if (segment->hash && copied) {
202                 /*
203                  * If a segment is kmapd we must unmap it before sending
204                  * to the crypto layer since that will try to kmap it again.
205                  */
206                 iscsi_tcp_segment_unmap(segment);
207
208                 if (!segment->data) {
209                         sg_init_table(&sg, 1);
210                         sg_set_page(&sg, sg_page(segment->sg), copied,
211                                     segment->copied + segment->sg_offset +
212                                                         segment->sg->offset);
213                 } else
214                         sg_init_one(&sg, segment->data + segment->copied,
215                                     copied);
216                 crypto_hash_update(segment->hash, &sg, copied);
217         }
218
219         segment->copied += copied;
220         if (segment->copied < segment->size) {
221                 iscsi_tcp_segment_map(segment, recv);
222                 return 0;
223         }
224
225         segment->total_copied += segment->copied;
226         segment->copied = 0;
227         segment->size = 0;
228
229         /* Unmap the current scatterlist page, if there is one. */
230         iscsi_tcp_segment_unmap(segment);
231
232         /* Do we have more scatterlist entries? */
233         ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "total copied %u total size %u\n",
234                       segment->total_copied, segment->total_size);
235         if (segment->total_copied < segment->total_size) {
236                 /* Proceed to the next entry in the scatterlist. */
237                 iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
238                                           0);
239                 iscsi_tcp_segment_map(segment, recv);
240                 BUG_ON(segment->size == 0);
241                 return 0;
242         }
243
244         /* Do we need to handle padding? */
245         if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
246                 pad = iscsi_padding(segment->total_copied);
247                 if (pad != 0) {
248                         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
249                                       "consume %d pad bytes\n", pad);
250                         segment->total_size += pad;
251                         segment->size = pad;
252                         segment->data = segment->padbuf;
253                         return 0;
254                 }
255         }
256
257         /*
258          * Set us up for transferring the data digest. hdr digest
259          * is completely handled in hdr done function.
260          */
261         if (segment->hash) {
262                 crypto_hash_final(segment->hash, segment->digest);
263                 iscsi_tcp_segment_splice_digest(segment,
264                                  recv ? segment->recv_digest : segment->digest);
265                 return 0;
266         }
267
268         return 1;
269 }
270 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);
271
272 /**
273  * iscsi_tcp_segment_recv - copy data to segment
274  * @tcp_conn: the iSCSI TCP connection
275  * @segment: the buffer to copy to
276  * @ptr: data pointer
277  * @len: amount of data available
278  *
279  * This function copies up to @len bytes to the
280  * given buffer, and returns the number of bytes
281  * consumed, which can actually be less than @len.
282  *
283  * If hash digest is enabled, the function will update the
284  * hash while copying.
285  * Combining these two operations doesn't buy us a lot (yet),
286  * but in the future we could implement combined copy+crc,
287  * just way we do for network layer checksums.
288  */
289 static int
290 iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
291                        struct iscsi_segment *segment, const void *ptr,
292                        unsigned int len)
293 {
294         unsigned int copy = 0, copied = 0;
295
296         while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
297                 if (copied == len) {
298                         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
299                                       "copied %d bytes\n", len);
300                         break;
301                 }
302
303                 copy = min(len - copied, segment->size - segment->copied);
304                 ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copying %d\n", copy);
305                 memcpy(segment->data + segment->copied, ptr + copied, copy);
306                 copied += copy;
307         }
308         return copied;
309 }
310
311 inline void
312 iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
313                       unsigned char digest[ISCSI_DIGEST_SIZE])
314 {
315         struct scatterlist sg;
316
317         sg_init_one(&sg, hdr, hdrlen);
318         crypto_hash_digest(hash, &sg, hdrlen, digest);
319 }
320 EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
321
322 static inline int
323 iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
324                       struct iscsi_segment *segment)
325 {
326         if (!segment->digest_len)
327                 return 1;
328
329         if (memcmp(segment->recv_digest, segment->digest,
330                    segment->digest_len)) {
331                 ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "digest mismatch\n");
332                 return 0;
333         }
334
335         return 1;
336 }
337
338 /*
339  * Helper function to set up segment buffer
340  */
341 static inline void
342 __iscsi_segment_init(struct iscsi_segment *segment, size_t size,
343                      iscsi_segment_done_fn_t *done, struct hash_desc *hash)
344 {
345         memset(segment, 0, sizeof(*segment));
346         segment->total_size = size;
347         segment->done = done;
348
349         if (hash) {
350                 segment->hash = hash;
351                 crypto_hash_init(hash);
352         }
353 }
354
355 inline void
356 iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
357                           size_t size, iscsi_segment_done_fn_t *done,
358                           struct hash_desc *hash)
359 {
360         __iscsi_segment_init(segment, size, done, hash);
361         segment->data = data;
362         segment->size = size;
363 }
364 EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
365
366 inline int
367 iscsi_segment_seek_sg(struct iscsi_segment *segment,
368                       struct scatterlist *sg_list, unsigned int sg_count,
369                       unsigned int offset, size_t size,
370                       iscsi_segment_done_fn_t *done, struct hash_desc *hash)
371 {
372         struct scatterlist *sg;
373         unsigned int i;
374
375         __iscsi_segment_init(segment, size, done, hash);
376         for_each_sg(sg_list, sg, sg_count, i) {
377                 if (offset < sg->length) {
378                         iscsi_tcp_segment_init_sg(segment, sg, offset);
379                         return 0;
380                 }
381                 offset -= sg->length;
382         }
383
384         return ISCSI_ERR_DATA_OFFSET;
385 }
386 EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);
387
388 /**
389  * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
390  * @tcp_conn: iscsi connection to prep for
391  *
392  * This function always passes NULL for the hash argument, because when this
393  * function is called we do not yet know the final size of the header and want
394  * to delay the digest processing until we know that.
395  */
396 void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
397 {
398         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
399                       "(%s)\n", tcp_conn->iscsi_conn->hdrdgst_en ?
400                       "digest enabled" : "digest disabled");
401         iscsi_segment_init_linear(&tcp_conn->in.segment,
402                                 tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
403                                 iscsi_tcp_hdr_recv_done, NULL);
404 }
405 EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
406
407 /*
408  * Handle incoming reply to any other type of command
409  */
410 static int
411 iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
412                          struct iscsi_segment *segment)
413 {
414         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
415         int rc = 0;
416
417         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
418                 return ISCSI_ERR_DATA_DGST;
419
420         rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
421                         conn->data, tcp_conn->in.datalen);
422         if (rc)
423                 return rc;
424
425         iscsi_tcp_hdr_recv_prep(tcp_conn);
426         return 0;
427 }
428
429 static void
430 iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
431 {
432         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
433         struct hash_desc *rx_hash = NULL;
434
435         if (conn->datadgst_en &&
436             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
437                 rx_hash = tcp_conn->rx_hash;
438
439         iscsi_segment_init_linear(&tcp_conn->in.segment,
440                                 conn->data, tcp_conn->in.datalen,
441                                 iscsi_tcp_data_recv_done, rx_hash);
442 }
443
444 /**
445  * iscsi_tcp_cleanup_task - free tcp_task resources
446  * @task: iscsi task
447  *
448  * must be called with session lock
449  */
450 void iscsi_tcp_cleanup_task(struct iscsi_task *task)
451 {
452         struct iscsi_tcp_task *tcp_task = task->dd_data;
453         struct iscsi_r2t_info *r2t;
454
455         /* nothing to do for mgmt */
456         if (!task->sc)
457                 return;
458
459         /* flush task's r2t queues */
460         while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
461                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
462                             sizeof(void*));
463                 ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
464         }
465
466         r2t = tcp_task->r2t;
467         if (r2t != NULL) {
468                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
469                             sizeof(void*));
470                 tcp_task->r2t = NULL;
471         }
472 }
473 EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
474
475 /**
476  * iscsi_tcp_data_in - SCSI Data-In Response processing
477  * @conn: iscsi connection
478  * @task: scsi command task
479  */
480 static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
481 {
482         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
483         struct iscsi_tcp_task *tcp_task = task->dd_data;
484         struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
485         int datasn = be32_to_cpu(rhdr->datasn);
486         unsigned total_in_length = scsi_in(task->sc)->length;
487
488         /*
489          * lib iscsi will update this in the completion handling if there
490          * is status.
491          */
492         if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
493                 iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);
494
495         if (tcp_conn->in.datalen == 0)
496                 return 0;
497
498         if (tcp_task->exp_datasn != datasn) {
499                 ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->datasn(%d)"
500                               "\n", tcp_task->exp_datasn, datasn);
501                 return ISCSI_ERR_DATASN;
502         }
503
504         tcp_task->exp_datasn++;
505
506         tcp_task->data_offset = be32_to_cpu(rhdr->offset);
507         if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
508                 ISCSI_DBG_TCP(conn, "data_offset(%d) + data_len(%d) > "
509                               "total_length_in(%d)\n", tcp_task->data_offset,
510                               tcp_conn->in.datalen, total_in_length);
511                 return ISCSI_ERR_DATA_OFFSET;
512         }
513
514         conn->datain_pdus_cnt++;
515         return 0;
516 }
517
518 /**
519  * iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
520  * @conn: iscsi connection
521  * @task: scsi command task
522  */
523 static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
524 {
525         struct iscsi_session *session = conn->session;
526         struct iscsi_tcp_task *tcp_task = task->dd_data;
527         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
528         struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
529         struct iscsi_r2t_info *r2t;
530         int r2tsn = be32_to_cpu(rhdr->r2tsn);
531         int rc;
532
533         if (tcp_conn->in.datalen) {
534                 iscsi_conn_printk(KERN_ERR, conn,
535                                   "invalid R2t with datalen %d\n",
536                                   tcp_conn->in.datalen);
537                 return ISCSI_ERR_DATALEN;
538         }
539
540         if (tcp_task->exp_datasn != r2tsn){
541                 ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
542                               tcp_task->exp_datasn, r2tsn);
543                 return ISCSI_ERR_R2TSN;
544         }
545
546         /* fill-in new R2T associated with the task */
547         iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
548
549         if (!task->sc || session->state != ISCSI_STATE_LOGGED_IN) {
550                 iscsi_conn_printk(KERN_INFO, conn,
551                                   "dropping R2T itt %d in recovery.\n",
552                                   task->itt);
553                 return 0;
554         }
555
556         rc = kfifo_out(&tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
557         if (!rc) {
558                 iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
559                                   "Target has sent more R2Ts than it "
560                                   "negotiated for or driver has has leaked.\n");
561                 return ISCSI_ERR_PROTO;
562         }
563
564         r2t->exp_statsn = rhdr->statsn;
565         r2t->data_length = be32_to_cpu(rhdr->data_length);
566         if (r2t->data_length == 0) {
567                 iscsi_conn_printk(KERN_ERR, conn,
568                                   "invalid R2T with zero data len\n");
569                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
570                             sizeof(void*));
571                 return ISCSI_ERR_DATALEN;
572         }
573
574         if (r2t->data_length > session->max_burst)
575                 ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
576                               "burst %u. Attempting to execute request.\n",
577                               r2t->data_length, session->max_burst);
578
579         r2t->data_offset = be32_to_cpu(rhdr->data_offset);
580         if (r2t->data_offset + r2t->data_length > scsi_out(task->sc)->length) {
581                 iscsi_conn_printk(KERN_ERR, conn,
582                                   "invalid R2T with data len %u at offset %u "
583                                   "and total length %d\n", r2t->data_length,
584                                   r2t->data_offset, scsi_out(task->sc)->length);
585                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
586                             sizeof(void*));
587                 return ISCSI_ERR_DATALEN;
588         }
589
590         r2t->ttt = rhdr->ttt; /* no flip */
591         r2t->datasn = 0;
592         r2t->sent = 0;
593
594         tcp_task->exp_datasn = r2tsn + 1;
595         kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
596         conn->r2t_pdus_cnt++;
597
598         iscsi_requeue_task(task);
599         return 0;
600 }
601
602 /*
603  * Handle incoming reply to DataIn command
604  */
605 static int
606 iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
607                           struct iscsi_segment *segment)
608 {
609         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
610         struct iscsi_hdr *hdr = tcp_conn->in.hdr;
611         int rc;
612
613         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
614                 return ISCSI_ERR_DATA_DGST;
615
616         /* check for non-exceptional status */
617         if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
618                 rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
619                 if (rc)
620                         return rc;
621         }
622
623         iscsi_tcp_hdr_recv_prep(tcp_conn);
624         return 0;
625 }
626
627 /**
628  * iscsi_tcp_hdr_dissect - process PDU header
629  * @conn: iSCSI connection
630  * @hdr: PDU header
631  *
632  * This function analyzes the header of the PDU received,
633  * and performs several sanity checks. If the PDU is accompanied
634  * by data, the receive buffer is set up to copy the incoming data
635  * to the correct location.
636  */
637 static int
638 iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
639 {
640         int rc = 0, opcode, ahslen;
641         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
642         struct iscsi_task *task;
643
644         /* verify PDU length */
645         tcp_conn->in.datalen = ntoh24(hdr->dlength);
646         if (tcp_conn->in.datalen > conn->max_recv_dlength) {
647                 iscsi_conn_printk(KERN_ERR, conn,
648                                   "iscsi_tcp: datalen %d > %d\n",
649                                   tcp_conn->in.datalen, conn->max_recv_dlength);
650                 return ISCSI_ERR_DATALEN;
651         }
652
653         /* Additional header segments. So far, we don't
654          * process additional headers.
655          */
656         ahslen = hdr->hlength << 2;
657
658         opcode = hdr->opcode & ISCSI_OPCODE_MASK;
659         /* verify itt (itt encoding: age+cid+itt) */
660         rc = iscsi_verify_itt(conn, hdr->itt);
661         if (rc)
662                 return rc;
663
664         ISCSI_DBG_TCP(conn, "opcode 0x%x ahslen %d datalen %d\n",
665                       opcode, ahslen, tcp_conn->in.datalen);
666
667         switch(opcode) {
668         case ISCSI_OP_SCSI_DATA_IN:
669                 spin_lock(&conn->session->lock);
670                 task = iscsi_itt_to_ctask(conn, hdr->itt);
671                 if (!task)
672                         rc = ISCSI_ERR_BAD_ITT;
673                 else
674                         rc = iscsi_tcp_data_in(conn, task);
675                 if (rc) {
676                         spin_unlock(&conn->session->lock);
677                         break;
678                 }
679
680                 if (tcp_conn->in.datalen) {
681                         struct iscsi_tcp_task *tcp_task = task->dd_data;
682                         struct hash_desc *rx_hash = NULL;
683                         struct scsi_data_buffer *sdb = scsi_in(task->sc);
684
685                         /*
686                          * Setup copy of Data-In into the Scsi_Cmnd
687                          * Scatterlist case:
688                          * We set up the iscsi_segment to point to the next
689                          * scatterlist entry to copy to. As we go along,
690                          * we move on to the next scatterlist entry and
691                          * update the digest per-entry.
692                          */
693                         if (conn->datadgst_en &&
694                             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
695                                 rx_hash = tcp_conn->rx_hash;
696
697                         ISCSI_DBG_TCP(conn, "iscsi_tcp_begin_data_in( "
698                                      "offset=%d, datalen=%d)\n",
699                                       tcp_task->data_offset,
700                                       tcp_conn->in.datalen);
701                         task->last_xfer = jiffies;
702                         rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
703                                                    sdb->table.sgl,
704                                                    sdb->table.nents,
705                                                    tcp_task->data_offset,
706                                                    tcp_conn->in.datalen,
707                                                    iscsi_tcp_process_data_in,
708                                                    rx_hash);
709                         spin_unlock(&conn->session->lock);
710                         return rc;
711                 }
712                 rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
713                 spin_unlock(&conn->session->lock);
714                 break;
715         case ISCSI_OP_SCSI_CMD_RSP:
716                 if (tcp_conn->in.datalen) {
717                         iscsi_tcp_data_recv_prep(tcp_conn);
718                         return 0;
719                 }
720                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
721                 break;
722         case ISCSI_OP_R2T:
723                 spin_lock(&conn->session->lock);
724                 task = iscsi_itt_to_ctask(conn, hdr->itt);
725                 if (!task)
726                         rc = ISCSI_ERR_BAD_ITT;
727                 else if (ahslen)
728                         rc = ISCSI_ERR_AHSLEN;
729                 else if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
730                         task->last_xfer = jiffies;
731                         rc = iscsi_tcp_r2t_rsp(conn, task);
732                 } else
733                         rc = ISCSI_ERR_PROTO;
734                 spin_unlock(&conn->session->lock);
735                 break;
736         case ISCSI_OP_LOGIN_RSP:
737         case ISCSI_OP_TEXT_RSP:
738         case ISCSI_OP_REJECT:
739         case ISCSI_OP_ASYNC_EVENT:
740                 /*
741                  * It is possible that we could get a PDU with a buffer larger
742                  * than 8K, but there are no targets that currently do this.
743                  * For now we fail until we find a vendor that needs it
744                  */
745                 if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
746                         iscsi_conn_printk(KERN_ERR, conn,
747                                           "iscsi_tcp: received buffer of "
748                                           "len %u but conn buffer is only %u "
749                                           "(opcode %0x)\n",
750                                           tcp_conn->in.datalen,
751                                           ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
752                         rc = ISCSI_ERR_PROTO;
753                         break;
754                 }
755
756                 /* If there's data coming in with the response,
757                  * receive it to the connection's buffer.
758                  */
759                 if (tcp_conn->in.datalen) {
760                         iscsi_tcp_data_recv_prep(tcp_conn);
761                         return 0;
762                 }
763         /* fall through */
764         case ISCSI_OP_LOGOUT_RSP:
765         case ISCSI_OP_NOOP_IN:
766         case ISCSI_OP_SCSI_TMFUNC_RSP:
767                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
768                 break;
769         default:
770                 rc = ISCSI_ERR_BAD_OPCODE;
771                 break;
772         }
773
774         if (rc == 0) {
775                 /* Anything that comes with data should have
776                  * been handled above. */
777                 if (tcp_conn->in.datalen)
778                         return ISCSI_ERR_PROTO;
779                 iscsi_tcp_hdr_recv_prep(tcp_conn);
780         }
781
782         return rc;
783 }
784
785 /**
786  * iscsi_tcp_hdr_recv_done - process PDU header
787  *
788  * This is the callback invoked when the PDU header has
789  * been received. If the header is followed by additional
790  * header segments, we go back for more data.
791  */
792 static int
793 iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
794                         struct iscsi_segment *segment)
795 {
796         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
797         struct iscsi_hdr *hdr;
798
799         /* Check if there are additional header segments
800          * *prior* to computing the digest, because we
801          * may need to go back to the caller for more.
802          */
803         hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
804         if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
805                 /* Bump the header length - the caller will
806                  * just loop around and get the AHS for us, and
807                  * call again. */
808                 unsigned int ahslen = hdr->hlength << 2;
809
810                 /* Make sure we don't overflow */
811                 if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
812                         return ISCSI_ERR_AHSLEN;
813
814                 segment->total_size += ahslen;
815                 segment->size += ahslen;
816                 return 0;
817         }
818
819         /* We're done processing the header. See if we're doing
820          * header digests; if so, set up the recv_digest buffer
821          * and go back for more. */
822         if (conn->hdrdgst_en &&
823             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
824                 if (segment->digest_len == 0) {
825                         /*
826                          * Even if we offload the digest processing we
827                          * splice it in so we can increment the skb/segment
828                          * counters in preparation for the data segment.
829                          */
830                         iscsi_tcp_segment_splice_digest(segment,
831                                                         segment->recv_digest);
832                         return 0;
833                 }
834
835                 iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
836                                       segment->total_copied - ISCSI_DIGEST_SIZE,
837                                       segment->digest);
838
839                 if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
840                         return ISCSI_ERR_HDR_DGST;
841         }
842
843         tcp_conn->in.hdr = hdr;
844         return iscsi_tcp_hdr_dissect(conn, hdr);
845 }
846
847 /**
848  * iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
849  * @tcp_conn: iscsi tcp conn
850  *
851  * returns non zero if we are currently processing or setup to process
852  * a header.
853  */
854 inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
855 {
856         return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
857 }
858 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);
859
860 /**
861  * iscsi_tcp_recv_skb - Process skb
862  * @conn: iscsi connection
863  * @skb: network buffer with header and/or data segment
864  * @offset: offset in skb
865  * @offload: bool indicating if transfer was offloaded
866  *
867  * Will return status of transfer in status. And will return
868  * number of bytes copied.
869  */
870 int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
871                        unsigned int offset, bool offloaded, int *status)
872 {
873         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
874         struct iscsi_segment *segment = &tcp_conn->in.segment;
875         struct skb_seq_state seq;
876         unsigned int consumed = 0;
877         int rc = 0;
878
879         ISCSI_DBG_TCP(conn, "in %d bytes\n", skb->len - offset);
880         /*
881          * Update for each skb instead of pdu, because over slow networks a
882          * data_in's data could take a while to read in. We also want to
883          * account for r2ts.
884          */
885         conn->last_recv = jiffies;
886
887         if (unlikely(conn->suspend_rx)) {
888                 ISCSI_DBG_TCP(conn, "Rx suspended!\n");
889                 *status = ISCSI_TCP_SUSPENDED;
890                 return 0;
891         }
892
893         if (offloaded) {
894                 segment->total_copied = segment->total_size;
895                 goto segment_done;
896         }
897
898         skb_prepare_seq_read(skb, offset, skb->len, &seq);
899         while (1) {
900                 unsigned int avail;
901                 const u8 *ptr;
902
903                 avail = skb_seq_read(consumed, &ptr, &seq);
904                 if (avail == 0) {
905                         ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
906                                       consumed);
907                         *status = ISCSI_TCP_SKB_DONE;
908                         skb_abort_seq_read(&seq);
909                         goto skb_done;
910                 }
911                 BUG_ON(segment->copied >= segment->size);
912
913                 ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
914                               avail);
915                 rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
916                 BUG_ON(rc == 0);
917                 consumed += rc;
918
919                 if (segment->total_copied >= segment->total_size) {
920                         skb_abort_seq_read(&seq);
921                         goto segment_done;
922                 }
923         }
924
925 segment_done:
926         *status = ISCSI_TCP_SEGMENT_DONE;
927         ISCSI_DBG_TCP(conn, "segment done\n");
928         rc = segment->done(tcp_conn, segment);
929         if (rc != 0) {
930                 *status = ISCSI_TCP_CONN_ERR;
931                 ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
932                 iscsi_conn_failure(conn, rc);
933                 return 0;
934         }
935         /* The done() functions sets up the next segment. */
936
937 skb_done:
938         conn->rxdata_octets += consumed;
939         return consumed;
940 }
941 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
942
943 /**
944  * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
945  * @conn: iscsi connection
946  * @task: scsi command task
947  * @sc: scsi command
948  */
949 int iscsi_tcp_task_init(struct iscsi_task *task)
950 {
951         struct iscsi_tcp_task *tcp_task = task->dd_data;
952         struct iscsi_conn *conn = task->conn;
953         struct scsi_cmnd *sc = task->sc;
954         int err;
955
956         if (!sc) {
957                 /*
958                  * mgmt tasks do not have a scatterlist since they come
959                  * in from the iscsi interface.
960                  */
961                 ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);
962
963                 return conn->session->tt->init_pdu(task, 0, task->data_count);
964         }
965
966         BUG_ON(kfifo_len(&tcp_task->r2tqueue));
967         tcp_task->exp_datasn = 0;
968
969         /* Prepare PDU, optionally w/ immediate data */
970         ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
971                       task->itt, task->imm_count, task->unsol_r2t.data_length);
972
973         err = conn->session->tt->init_pdu(task, 0, task->imm_count);
974         if (err)
975                 return err;
976         task->imm_count = 0;
977         return 0;
978 }
979 EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
980
981 static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
982 {
983         struct iscsi_session *session = task->conn->session;
984         struct iscsi_tcp_task *tcp_task = task->dd_data;
985         struct iscsi_r2t_info *r2t = NULL;
986
987         if (iscsi_task_has_unsol_data(task))
988                 r2t = &task->unsol_r2t;
989         else {
990                 spin_lock_bh(&session->lock);
991                 if (tcp_task->r2t) {
992                         r2t = tcp_task->r2t;
993                         /* Continue with this R2T? */
994                         if (r2t->data_length <= r2t->sent) {
995                                 ISCSI_DBG_TCP(task->conn,
996                                               "  done with r2t %p\n", r2t);
997                                 kfifo_in(&tcp_task->r2tpool.queue,
998                                             (void *)&tcp_task->r2t,
999                                             sizeof(void *));
1000                                 tcp_task->r2t = r2t = NULL;
1001                         }
1002                 }
1003
1004                 if (r2t == NULL) {
1005                         if (kfifo_out(&tcp_task->r2tqueue,
1006                             (void *)&tcp_task->r2t, sizeof(void *)) !=
1007                             sizeof(void *))
1008                                 r2t = NULL;
1009                         else
1010                                 r2t = tcp_task->r2t;
1011                 }
1012                 spin_unlock_bh(&session->lock);
1013         }
1014
1015         return r2t;
1016 }
1017
1018 /**
1019  * iscsi_tcp_task_xmit - xmit normal PDU task
1020  * @task: iscsi command task
1021  *
1022  * We're expected to return 0 when everything was transmitted successfully,
1023  * -EAGAIN if there's still data in the queue, or != 0 for any other kind
1024  * of error.
1025  */
1026 int iscsi_tcp_task_xmit(struct iscsi_task *task)
1027 {
1028         struct iscsi_conn *conn = task->conn;
1029         struct iscsi_session *session = conn->session;
1030         struct iscsi_r2t_info *r2t;
1031         int rc = 0;
1032
1033 flush:
1034         /* Flush any pending data first. */
1035         rc = session->tt->xmit_pdu(task);
1036         if (rc < 0)
1037                 return rc;
1038
1039         /* mgmt command */
1040         if (!task->sc) {
1041                 if (task->hdr->itt == RESERVED_ITT)
1042                         iscsi_put_task(task);
1043                 return 0;
1044         }
1045
1046         /* Are we done already? */
1047         if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1048                 return 0;
1049
1050         r2t = iscsi_tcp_get_curr_r2t(task);
1051         if (r2t == NULL) {
1052                 /* Waiting for more R2Ts to arrive. */
1053                 ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
1054                 return 0;
1055         }
1056
1057         rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1058         if (rc)
1059                 return rc;
1060         iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1061
1062         ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1063                       r2t, r2t->datasn - 1, task->hdr->itt,
1064                       r2t->data_offset + r2t->sent, r2t->data_count);
1065
1066         rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1067                                          r2t->data_count);
1068         if (rc) {
1069                 iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
1070                 return rc;
1071         }
1072
1073         r2t->sent += r2t->data_count;
1074         goto flush;
1075 }
1076 EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1077
1078 struct iscsi_cls_conn *
1079 iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1080                       uint32_t conn_idx)
1081
1082 {
1083         struct iscsi_conn *conn;
1084         struct iscsi_cls_conn *cls_conn;
1085         struct iscsi_tcp_conn *tcp_conn;
1086
1087         cls_conn = iscsi_conn_setup(cls_session, sizeof(*tcp_conn), conn_idx);
1088         if (!cls_conn)
1089                 return NULL;
1090         conn = cls_conn->dd_data;
1091         /*
1092          * due to strange issues with iser these are not set
1093          * in iscsi_conn_setup
1094          */
1095         conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1096
1097         tcp_conn = conn->dd_data;
1098         tcp_conn->iscsi_conn = conn;
1099
1100         tcp_conn->dd_data = kzalloc(dd_data_size, GFP_KERNEL);
1101         if (!tcp_conn->dd_data) {
1102                 iscsi_conn_teardown(cls_conn);
1103                 return NULL;
1104         }
1105         return cls_conn;
1106 }
1107 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1108
1109 void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1110 {
1111         struct iscsi_conn *conn = cls_conn->dd_data;
1112         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
1113
1114         kfree(tcp_conn->dd_data);
1115         iscsi_conn_teardown(cls_conn);
1116 }
1117 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1118
1119 int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1120 {
1121         int i;
1122         int cmd_i;
1123
1124         /*
1125          * initialize per-task: R2T pool and xmit queue
1126          */
1127         for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1128                 struct iscsi_task *task = session->cmds[cmd_i];
1129                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1130
1131                 /*
1132                  * pre-allocated x2 as much r2ts to handle race when
1133                  * target acks DataOut faster than we data_xmit() queues
1134                  * could replenish r2tqueue.
1135                  */
1136
1137                 /* R2T pool */
1138                 if (iscsi_pool_init(&tcp_task->r2tpool,
1139                                     session->max_r2t * 2, NULL,
1140                                     sizeof(struct iscsi_r2t_info))) {
1141                         goto r2t_alloc_fail;
1142                 }
1143
1144                 /* R2T xmit queue */
1145                 if (kfifo_alloc(&tcp_task->r2tqueue,
1146                       session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
1147                         iscsi_pool_free(&tcp_task->r2tpool);
1148                         goto r2t_alloc_fail;
1149                 }
1150         }
1151
1152         return 0;
1153
1154 r2t_alloc_fail:
1155         for (i = 0; i < cmd_i; i++) {
1156                 struct iscsi_task *task = session->cmds[i];
1157                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1158
1159                 kfifo_free(&tcp_task->r2tqueue);
1160                 iscsi_pool_free(&tcp_task->r2tpool);
1161         }
1162         return -ENOMEM;
1163 }
1164 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1165
1166 void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1167 {
1168         int i;
1169
1170         for (i = 0; i < session->cmds_max; i++) {
1171                 struct iscsi_task *task = session->cmds[i];
1172                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1173
1174                 kfifo_free(&tcp_task->r2tqueue);
1175                 iscsi_pool_free(&tcp_task->r2tpool);
1176         }
1177 }
1178 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1179
1180 void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1181                               struct iscsi_stats *stats)
1182 {
1183         struct iscsi_conn *conn = cls_conn->dd_data;
1184
1185         stats->txdata_octets = conn->txdata_octets;
1186         stats->rxdata_octets = conn->rxdata_octets;
1187         stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1188         stats->dataout_pdus = conn->dataout_pdus_cnt;
1189         stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1190         stats->datain_pdus = conn->datain_pdus_cnt;
1191         stats->r2t_pdus = conn->r2t_pdus_cnt;
1192         stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1193         stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1194 }
1195 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);