1 /*******************************************************************************
2  * Filename:  target_core_rd.c
3  *
4  * This file contains the Storage Engine <-> Ramdisk transport
5  * specific functions.
6  *
7  * Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
8  * Copyright (c) 2005, 2006, 2007 SBE, Inc.
9  * Copyright (c) 2007-2010 Rising Tide Systems
10  * Copyright (c) 2008-2010 Linux-iSCSI.org
11  *
12  * Nicholas A. Bellinger <nab@kernel.org>
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License as published by
16  * the Free Software Foundation; either version 2 of the License, or
17  * (at your option) any later version.
18  *
19  * This program is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22  * GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with this program; if not, write to the Free Software
26  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27  *
28  ******************************************************************************/
29 
30 #include <linux/string.h>
31 #include <linux/parser.h>
32 #include <linux/timer.h>
33 #include <linux/blkdev.h>
34 #include <linux/slab.h>
35 #include <linux/spinlock.h>
36 #include <scsi/scsi.h>
37 #include <scsi/scsi_host.h>
38 
39 #include <target/target_core_base.h>
40 #include <target/target_core_backend.h>
41 
42 #include "target_core_rd.h"
43 
44 static struct se_subsystem_api rd_mcp_template;
45 
46 /*	rd_attach_hba(): (Part of se_subsystem_api_t template)
47  *
48  *
49  */
50 static int rd_attach_hba(struct se_hba *hba, u32 host_id)
51 {
52 	struct rd_host *rd_host;
53 
54 	rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL);
55 	if (!rd_host) {
56 		pr_err("Unable to allocate memory for struct rd_host\n");
57 		return -ENOMEM;
58 	}
59 
60 	rd_host->rd_host_id = host_id;
61 
62 	hba->hba_ptr = rd_host;
63 
64 	pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
65 		" Generic Target Core Stack %s\n", hba->hba_id,
66 		RD_HBA_VERSION, TARGET_CORE_MOD_VERSION);
67 
68 	return 0;
69 }
70 
71 static void rd_detach_hba(struct se_hba *hba)
72 {
73 	struct rd_host *rd_host = hba->hba_ptr;
74 
75 	pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
76 		" Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);
77 
78 	kfree(rd_host);
79 	hba->hba_ptr = NULL;
80 }
81 
82 /*	rd_release_device_space():
83  *
84  *
85  */
86 static void rd_release_device_space(struct rd_dev *rd_dev)
87 {
88 	u32 i, j, page_count = 0, sg_per_table;
89 	struct rd_dev_sg_table *sg_table;
90 	struct page *pg;
91 	struct scatterlist *sg;
92 
93 	if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
94 		return;
95 
96 	sg_table = rd_dev->sg_table_array;
97 
98 	for (i = 0; i < rd_dev->sg_table_count; i++) {
99 		sg = sg_table[i].sg_table;
100 		sg_per_table = sg_table[i].rd_sg_count;
101 
102 		for (j = 0; j < sg_per_table; j++) {
103 			pg = sg_page(&sg[j]);
104 			if (pg) {
105 				__free_page(pg);
106 				page_count++;
107 			}
108 		}
109 
110 		kfree(sg);
111 	}
112 
113 	pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
114 		" Device ID: %u, pages %u in %u tables total bytes %lu\n",
115 		rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
116 		rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
117 
118 	kfree(sg_table);
119 	rd_dev->sg_table_array = NULL;
120 	rd_dev->sg_table_count = 0;
121 }
122 
123 
124 /*	rd_build_device_space():
125  *
126  *
127  */
128 static int rd_build_device_space(struct rd_dev *rd_dev)
129 {
130 	u32 i = 0, j, page_offset = 0, sg_per_table, sg_tables, total_sg_needed;
131 	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
132 				sizeof(struct scatterlist));
133 	struct rd_dev_sg_table *sg_table;
134 	struct page *pg;
135 	struct scatterlist *sg;
136 
137 	if (rd_dev->rd_page_count <= 0) {
138 		pr_err("Illegal page count: %u for Ramdisk device\n",
139 			rd_dev->rd_page_count);
140 		return -EINVAL;
141 	}
142 	total_sg_needed = rd_dev->rd_page_count;
143 
144 	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
145 
146 	sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
147 	if (!sg_table) {
148 		pr_err("Unable to allocate memory for Ramdisk"
149 			" scatterlist tables\n");
150 		return -ENOMEM;
151 	}
152 
153 	rd_dev->sg_table_array = sg_table;
154 	rd_dev->sg_table_count = sg_tables;
155 
156 	while (total_sg_needed) {
157 		sg_per_table = (total_sg_needed > max_sg_per_table) ?
158 			max_sg_per_table : total_sg_needed;
159 
160 		sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
161 				GFP_KERNEL);
162 		if (!sg) {
163 			pr_err("Unable to allocate scatterlist array"
164 				" for struct rd_dev\n");
165 			return -ENOMEM;
166 		}
167 
168 		sg_init_table(sg, sg_per_table);
169 
170 		sg_table[i].sg_table = sg;
171 		sg_table[i].rd_sg_count = sg_per_table;
172 		sg_table[i].page_start_offset = page_offset;
173 		sg_table[i++].page_end_offset = (page_offset + sg_per_table)
174 						- 1;
175 
176 		for (j = 0; j < sg_per_table; j++) {
177 			pg = alloc_pages(GFP_KERNEL, 0);
178 			if (!pg) {
179 				pr_err("Unable to allocate scatterlist"
180 					" pages for struct rd_dev_sg_table\n");
181 				return -ENOMEM;
182 			}
183 			sg_assign_page(&sg[j], pg);
184 			sg[j].length = PAGE_SIZE;
185 		}
186 
187 		page_offset += sg_per_table;
188 		total_sg_needed -= sg_per_table;
189 	}
190 
191 	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
192 		" %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
193 		rd_dev->rd_dev_id, rd_dev->rd_page_count,
194 		rd_dev->sg_table_count);
195 
196 	return 0;
197 }
198 
199 static void *rd_allocate_virtdevice(struct se_hba *hba, const char *name)
200 {
201 	struct rd_dev *rd_dev;
202 	struct rd_host *rd_host = hba->hba_ptr;
203 
204 	rd_dev = kzalloc(sizeof(struct rd_dev), GFP_KERNEL);
205 	if (!rd_dev) {
206 		pr_err("Unable to allocate memory for struct rd_dev\n");
207 		return NULL;
208 	}
209 
210 	rd_dev->rd_host = rd_host;
211 
212 	return rd_dev;
213 }
214 
215 static struct se_device *rd_create_virtdevice(struct se_hba *hba,
216 		struct se_subsystem_dev *se_dev, void *p)
217 {
218 	struct se_device *dev;
219 	struct se_dev_limits dev_limits;
220 	struct rd_dev *rd_dev = p;
221 	struct rd_host *rd_host = hba->hba_ptr;
222 	int dev_flags = 0, ret;
223 	char prod[16], rev[4];
224 
225 	memset(&dev_limits, 0, sizeof(struct se_dev_limits));
226 
227 	ret = rd_build_device_space(rd_dev);
228 	if (ret < 0)
229 		goto fail;
230 
231 	snprintf(prod, 16, "RAMDISK-MCP");
232 	snprintf(rev, 4, "%s", RD_MCP_VERSION);
233 
234 	dev_limits.limits.logical_block_size = RD_BLOCKSIZE;
235 	dev_limits.limits.max_hw_sectors = UINT_MAX;
236 	dev_limits.limits.max_sectors = UINT_MAX;
237 	dev_limits.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
238 	dev_limits.queue_depth = RD_DEVICE_QUEUE_DEPTH;
239 
240 	dev = transport_add_device_to_core_hba(hba,
241 			&rd_mcp_template, se_dev, dev_flags, rd_dev,
242 			&dev_limits, prod, rev);
243 	if (!dev)
244 		goto fail;
245 
246 	rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
247 
248 	pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
249 		" %u pages in %u tables, %lu total bytes\n",
250 		rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
251 		rd_dev->sg_table_count,
252 		(unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
253 
254 	return dev;
255 
256 fail:
257 	rd_release_device_space(rd_dev);
258 	return ERR_PTR(ret);
259 }
260 
261 static void rd_free_device(void *p)
262 {
263 	struct rd_dev *rd_dev = p;
264 
265 	rd_release_device_space(rd_dev);
266 	kfree(rd_dev);
267 }
268 
269 static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
270 {
271 	u32 i;
272 	struct rd_dev_sg_table *sg_table;
273 
274 	for (i = 0; i < rd_dev->sg_table_count; i++) {
275 		sg_table = &rd_dev->sg_table_array[i];
276 		if ((sg_table->page_start_offset <= page) &&
277 		    (sg_table->page_end_offset >= page))
278 			return sg_table;
279 	}
280 
281 	pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
282 			page);
283 
284 	return NULL;
285 }
286 
287 static int rd_execute_rw(struct se_cmd *cmd)
288 {
289 	struct scatterlist *sgl = cmd->t_data_sg;
290 	u32 sgl_nents = cmd->t_data_nents;
291 	enum dma_data_direction data_direction = cmd->data_direction;
292 	struct se_device *se_dev = cmd->se_dev;
293 	struct rd_dev *dev = se_dev->dev_ptr;
294 	struct rd_dev_sg_table *table;
295 	struct scatterlist *rd_sg;
296 	struct sg_mapping_iter m;
297 	u32 rd_offset;
298 	u32 rd_size;
299 	u32 rd_page;
300 	u32 src_len;
301 	u64 tmp;
302 
303 	tmp = cmd->t_task_lba * se_dev->se_sub_dev->se_dev_attrib.block_size;
304 	rd_offset = do_div(tmp, PAGE_SIZE);
305 	rd_page = tmp;
306 	rd_size = cmd->data_length;
307 
308 	table = rd_get_sg_table(dev, rd_page);
309 	if (!table)
310 		return -EINVAL;
311 
312 	rd_sg = &table->sg_table[rd_page - table->page_start_offset];
313 
314 	pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
315 			dev->rd_dev_id,
316 			data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
317 			cmd->t_task_lba, rd_size, rd_page, rd_offset);
318 
319 	src_len = PAGE_SIZE - rd_offset;
320 	sg_miter_start(&m, sgl, sgl_nents,
321 			data_direction == DMA_FROM_DEVICE ?
322 				SG_MITER_TO_SG : SG_MITER_FROM_SG);
323 	while (rd_size) {
324 		u32 len;
325 		void *rd_addr;
326 
327 		sg_miter_next(&m);
328 		len = min((u32)m.length, src_len);
329 		m.consumed = len;
330 
331 		rd_addr = sg_virt(rd_sg) + rd_offset;
332 
333 		if (data_direction == DMA_FROM_DEVICE)
334 			memcpy(m.addr, rd_addr, len);
335 		else
336 			memcpy(rd_addr, m.addr, len);
337 
338 		rd_size -= len;
339 		if (!rd_size)
340 			continue;
341 
342 		src_len -= len;
343 		if (src_len) {
344 			rd_offset += len;
345 			continue;
346 		}
347 
348 		/* rd page completed, next one please */
349 		rd_page++;
350 		rd_offset = 0;
351 		src_len = PAGE_SIZE;
352 		if (rd_page <= table->page_end_offset) {
353 			rd_sg++;
354 			continue;
355 		}
356 
357 		table = rd_get_sg_table(dev, rd_page);
358 		if (!table) {
359 			sg_miter_stop(&m);
360 			return -EINVAL;
361 		}
362 
363 		/* since we increment, the first sg entry is correct */
364 		rd_sg = table->sg_table;
365 	}
366 	sg_miter_stop(&m);
367 
368 	target_complete_cmd(cmd, SAM_STAT_GOOD);
369 	return 0;
370 }
371 
372 enum {
373 	Opt_rd_pages, Opt_err
374 };
375 
376 static match_table_t tokens = {
377 	{Opt_rd_pages, "rd_pages=%d"},
378 	{Opt_err, NULL}
379 };
380 
381 static ssize_t rd_set_configfs_dev_params(
382 	struct se_hba *hba,
383 	struct se_subsystem_dev *se_dev,
384 	const char *page,
385 	ssize_t count)
386 {
387 	struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
388 	char *orig, *ptr, *opts;
389 	substring_t args[MAX_OPT_ARGS];
390 	int ret = 0, arg, token;
391 
392 	opts = kstrdup(page, GFP_KERNEL);
393 	if (!opts)
394 		return -ENOMEM;
395 
396 	orig = opts;
397 
398 	while ((ptr = strsep(&opts, ",\n")) != NULL) {
399 		if (!*ptr)
400 			continue;
401 
402 		token = match_token(ptr, tokens, args);
403 		switch (token) {
404 		case Opt_rd_pages:
405 			match_int(args, &arg);
406 			rd_dev->rd_page_count = arg;
407 			pr_debug("RAMDISK: Referencing Page"
408 				" Count: %u\n", rd_dev->rd_page_count);
409 			rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
410 			break;
411 		default:
412 			break;
413 		}
414 	}
415 
416 	kfree(orig);
417 	return (!ret) ? count : ret;
418 }
419 
420 static ssize_t rd_check_configfs_dev_params(struct se_hba *hba, struct se_subsystem_dev *se_dev)
421 {
422 	struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
423 
424 	if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
425 		pr_debug("Missing rd_pages= parameter\n");
426 		return -EINVAL;
427 	}
428 
429 	return 0;
430 }
431 
432 static ssize_t rd_show_configfs_dev_params(
433 	struct se_hba *hba,
434 	struct se_subsystem_dev *se_dev,
435 	char *b)
436 {
437 	struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
438 	ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
439 			rd_dev->rd_dev_id);
440 	bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
441 			"  SG_table_count: %u\n", rd_dev->rd_page_count,
442 			PAGE_SIZE, rd_dev->sg_table_count);
443 	return bl;
444 }
445 
446 static u32 rd_get_device_rev(struct se_device *dev)
447 {
448 	return SCSI_SPC_2; /* Returns SPC-3 in Initiator Data */
449 }
450 
451 static u32 rd_get_device_type(struct se_device *dev)
452 {
453 	return TYPE_DISK;
454 }
455 
456 static sector_t rd_get_blocks(struct se_device *dev)
457 {
458 	struct rd_dev *rd_dev = dev->dev_ptr;
459 	unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
460 			dev->se_sub_dev->se_dev_attrib.block_size) - 1;
461 
462 	return blocks_long;
463 }
464 
465 static struct spc_ops rd_spc_ops = {
466 	.execute_rw		= rd_execute_rw,
467 };
468 
469 static int rd_parse_cdb(struct se_cmd *cmd)
470 {
471 	return sbc_parse_cdb(cmd, &rd_spc_ops);
472 }
473 
474 static struct se_subsystem_api rd_mcp_template = {
475 	.name			= "rd_mcp",
476 	.transport_type		= TRANSPORT_PLUGIN_VHBA_VDEV,
477 	.attach_hba		= rd_attach_hba,
478 	.detach_hba		= rd_detach_hba,
479 	.allocate_virtdevice	= rd_allocate_virtdevice,
480 	.create_virtdevice	= rd_create_virtdevice,
481 	.free_device		= rd_free_device,
482 	.parse_cdb		= rd_parse_cdb,
483 	.check_configfs_dev_params = rd_check_configfs_dev_params,
484 	.set_configfs_dev_params = rd_set_configfs_dev_params,
485 	.show_configfs_dev_params = rd_show_configfs_dev_params,
486 	.get_device_rev		= rd_get_device_rev,
487 	.get_device_type	= rd_get_device_type,
488 	.get_blocks		= rd_get_blocks,
489 };
490 
491 int __init rd_module_init(void)
492 {
493 	int ret;
494 
495 	ret = transport_subsystem_register(&rd_mcp_template);
496 	if (ret < 0) {
497 		return ret;
498 	}
499 
500 	return 0;
501 }
502 
503 void rd_module_exit(void)
504 {
505 	transport_subsystem_release(&rd_mcp_template);
506 }
507