1 /*******************************************************************************
2  * Filename:  target_core_rd.c
3  *
4  * This file contains the Storage Engine <-> Ramdisk transport
5  * specific functions.
6  *
7  * (c) Copyright 2003-2012 RisingTide Systems LLC.
8  *
9  * Nicholas A. Bellinger <nab@kernel.org>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24  *
25  ******************************************************************************/
26 
27 #include <linux/string.h>
28 #include <linux/parser.h>
29 #include <linux/timer.h>
30 #include <linux/blkdev.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
33 #include <scsi/scsi.h>
34 #include <scsi/scsi_host.h>
35 
36 #include <target/target_core_base.h>
37 #include <target/target_core_backend.h>
38 
39 #include "target_core_rd.h"
40 
41 static inline struct rd_dev *RD_DEV(struct se_device *dev)
42 {
43 	return container_of(dev, struct rd_dev, dev);
44 }
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 struct se_device *rd_alloc_device(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->dev;
213 }
214 
215 static int rd_configure_device(struct se_device *dev)
216 {
217 	struct rd_dev *rd_dev = RD_DEV(dev);
218 	struct rd_host *rd_host = dev->se_hba->hba_ptr;
219 	int ret;
220 
221 	if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
222 		pr_debug("Missing rd_pages= parameter\n");
223 		return -EINVAL;
224 	}
225 
226 	ret = rd_build_device_space(rd_dev);
227 	if (ret < 0)
228 		goto fail;
229 
230 	dev->dev_attrib.hw_block_size = RD_BLOCKSIZE;
231 	dev->dev_attrib.hw_max_sectors = UINT_MAX;
232 	dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
233 
234 	rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
235 
236 	pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
237 		" %u pages in %u tables, %lu total bytes\n",
238 		rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
239 		rd_dev->sg_table_count,
240 		(unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
241 
242 	return 0;
243 
244 fail:
245 	rd_release_device_space(rd_dev);
246 	return ret;
247 }
248 
249 static void rd_free_device(struct se_device *dev)
250 {
251 	struct rd_dev *rd_dev = RD_DEV(dev);
252 
253 	rd_release_device_space(rd_dev);
254 	kfree(rd_dev);
255 }
256 
257 static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
258 {
259 	struct rd_dev_sg_table *sg_table;
260 	u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
261 				sizeof(struct scatterlist));
262 
263 	i = page / sg_per_table;
264 	if (i < rd_dev->sg_table_count) {
265 		sg_table = &rd_dev->sg_table_array[i];
266 		if ((sg_table->page_start_offset <= page) &&
267 		    (sg_table->page_end_offset >= page))
268 			return sg_table;
269 	}
270 
271 	pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
272 			page);
273 
274 	return NULL;
275 }
276 
277 static sense_reason_t
278 rd_execute_rw(struct se_cmd *cmd)
279 {
280 	struct scatterlist *sgl = cmd->t_data_sg;
281 	u32 sgl_nents = cmd->t_data_nents;
282 	enum dma_data_direction data_direction = cmd->data_direction;
283 	struct se_device *se_dev = cmd->se_dev;
284 	struct rd_dev *dev = RD_DEV(se_dev);
285 	struct rd_dev_sg_table *table;
286 	struct scatterlist *rd_sg;
287 	struct sg_mapping_iter m;
288 	u32 rd_offset;
289 	u32 rd_size;
290 	u32 rd_page;
291 	u32 src_len;
292 	u64 tmp;
293 
294 	tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
295 	rd_offset = do_div(tmp, PAGE_SIZE);
296 	rd_page = tmp;
297 	rd_size = cmd->data_length;
298 
299 	table = rd_get_sg_table(dev, rd_page);
300 	if (!table)
301 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
302 
303 	rd_sg = &table->sg_table[rd_page - table->page_start_offset];
304 
305 	pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
306 			dev->rd_dev_id,
307 			data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
308 			cmd->t_task_lba, rd_size, rd_page, rd_offset);
309 
310 	src_len = PAGE_SIZE - rd_offset;
311 	sg_miter_start(&m, sgl, sgl_nents,
312 			data_direction == DMA_FROM_DEVICE ?
313 				SG_MITER_TO_SG : SG_MITER_FROM_SG);
314 	while (rd_size) {
315 		u32 len;
316 		void *rd_addr;
317 
318 		sg_miter_next(&m);
319 		if (!(u32)m.length) {
320 			pr_debug("RD[%u]: invalid sgl %p len %zu\n",
321 				 dev->rd_dev_id, m.addr, m.length);
322 			sg_miter_stop(&m);
323 			return TCM_INCORRECT_AMOUNT_OF_DATA;
324 		}
325 		len = min((u32)m.length, src_len);
326 		if (len > rd_size) {
327 			pr_debug("RD[%u]: size underrun page %d offset %d "
328 				 "size %d\n", dev->rd_dev_id,
329 				 rd_page, rd_offset, rd_size);
330 			len = rd_size;
331 		}
332 		m.consumed = len;
333 
334 		rd_addr = sg_virt(rd_sg) + rd_offset;
335 
336 		if (data_direction == DMA_FROM_DEVICE)
337 			memcpy(m.addr, rd_addr, len);
338 		else
339 			memcpy(rd_addr, m.addr, len);
340 
341 		rd_size -= len;
342 		if (!rd_size)
343 			continue;
344 
345 		src_len -= len;
346 		if (src_len) {
347 			rd_offset += len;
348 			continue;
349 		}
350 
351 		/* rd page completed, next one please */
352 		rd_page++;
353 		rd_offset = 0;
354 		src_len = PAGE_SIZE;
355 		if (rd_page <= table->page_end_offset) {
356 			rd_sg++;
357 			continue;
358 		}
359 
360 		table = rd_get_sg_table(dev, rd_page);
361 		if (!table) {
362 			sg_miter_stop(&m);
363 			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
364 		}
365 
366 		/* since we increment, the first sg entry is correct */
367 		rd_sg = table->sg_table;
368 	}
369 	sg_miter_stop(&m);
370 
371 	target_complete_cmd(cmd, SAM_STAT_GOOD);
372 	return 0;
373 }
374 
375 enum {
376 	Opt_rd_pages, Opt_err
377 };
378 
379 static match_table_t tokens = {
380 	{Opt_rd_pages, "rd_pages=%d"},
381 	{Opt_err, NULL}
382 };
383 
384 static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
385 		const char *page, ssize_t count)
386 {
387 	struct rd_dev *rd_dev = RD_DEV(dev);
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_show_configfs_dev_params(struct se_device *dev, char *b)
421 {
422 	struct rd_dev *rd_dev = RD_DEV(dev);
423 
424 	ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
425 			rd_dev->rd_dev_id);
426 	bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
427 			"  SG_table_count: %u\n", rd_dev->rd_page_count,
428 			PAGE_SIZE, rd_dev->sg_table_count);
429 	return bl;
430 }
431 
432 static sector_t rd_get_blocks(struct se_device *dev)
433 {
434 	struct rd_dev *rd_dev = RD_DEV(dev);
435 
436 	unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
437 			dev->dev_attrib.block_size) - 1;
438 
439 	return blocks_long;
440 }
441 
442 static struct sbc_ops rd_sbc_ops = {
443 	.execute_rw		= rd_execute_rw,
444 };
445 
446 static sense_reason_t
447 rd_parse_cdb(struct se_cmd *cmd)
448 {
449 	return sbc_parse_cdb(cmd, &rd_sbc_ops);
450 }
451 
452 static struct se_subsystem_api rd_mcp_template = {
453 	.name			= "rd_mcp",
454 	.inquiry_prod		= "RAMDISK-MCP",
455 	.inquiry_rev		= RD_MCP_VERSION,
456 	.transport_type		= TRANSPORT_PLUGIN_VHBA_VDEV,
457 	.attach_hba		= rd_attach_hba,
458 	.detach_hba		= rd_detach_hba,
459 	.alloc_device		= rd_alloc_device,
460 	.configure_device	= rd_configure_device,
461 	.free_device		= rd_free_device,
462 	.parse_cdb		= rd_parse_cdb,
463 	.set_configfs_dev_params = rd_set_configfs_dev_params,
464 	.show_configfs_dev_params = rd_show_configfs_dev_params,
465 	.get_device_type	= sbc_get_device_type,
466 	.get_blocks		= rd_get_blocks,
467 };
468 
469 int __init rd_module_init(void)
470 {
471 	int ret;
472 
473 	ret = transport_subsystem_register(&rd_mcp_template);
474 	if (ret < 0) {
475 		return ret;
476 	}
477 
478 	return 0;
479 }
480 
481 void rd_module_exit(void)
482 {
483 	transport_subsystem_release(&rd_mcp_template);
484 }
485