dcssblk.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * dcssblk.c -- the S/390 block driver for dcss memory
   4 *
   5 * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   6 */
   7
   8#define pr_fmt(fmt) "dcssblk: " fmt
   9
  10#include <linux/module.h>
  11#include <linux/moduleparam.h>
  12#include <linux/ctype.h>
  13#include <linux/errno.h>
  14#include <linux/init.h>
  15#include <linux/slab.h>
  16#include <linux/blkdev.h>
  17#include <linux/completion.h>
  18#include <linux/interrupt.h>
  19#include <linux/uio.h>
  20#include <linux/dax.h>
  21#include <linux/io.h>
  22#include <asm/extmem.h>
  23
  24#define DCSSBLK_NAME "dcssblk"
  25#define DCSSBLK_MINORS_PER_DISK 1
  26#define DCSSBLK_PARM_LEN 400
  27#define DCSS_BUS_ID_SIZE 20
  28
  29static int dcssblk_open(struct gendisk *disk, blk_mode_t mode);
  30static void dcssblk_release(struct gendisk *disk);
  31static void dcssblk_submit_bio(struct bio *bio);
  32static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  33		long nr_pages, enum dax_access_mode mode, void **kaddr,
  34		unsigned long *pfn);
  35
  36static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  37
  38static int dcssblk_major;
  39static const struct block_device_operations dcssblk_devops = {
  40	.owner   	= THIS_MODULE,
  41	.submit_bio	= dcssblk_submit_bio,
  42	.open    	= dcssblk_open,
  43	.release 	= dcssblk_release,
  44};
  45
  46static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
  47				       pgoff_t pgoff, size_t nr_pages)
  48{
  49	long rc;
  50	void *kaddr;
  51
  52	rc = dax_direct_access(dax_dev, pgoff, nr_pages, DAX_ACCESS,
  53			&kaddr, NULL);
  54	if (rc < 0)
  55		return dax_mem2blk_err(rc);
  56
  57	memset(kaddr, 0, nr_pages << PAGE_SHIFT);
  58	dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
  59	return 0;
  60}
  61
  62static const struct dax_operations dcssblk_dax_ops = {
  63	.direct_access = dcssblk_dax_direct_access,
  64	.zero_page_range = dcssblk_dax_zero_page_range,
  65};
  66
  67struct dcssblk_dev_info {
  68	struct list_head lh;
  69	struct device dev;
  70	char segment_name[DCSS_BUS_ID_SIZE];
  71	atomic_t use_count;
  72	struct gendisk *gd;
  73	unsigned long start;
  74	unsigned long end;
  75	int segment_type;
  76	unsigned char save_pending;
  77	unsigned char is_shared;
  78	int num_of_segments;
  79	struct list_head seg_list;
  80	struct dax_device *dax_dev;
  81	struct dev_pagemap pgmap;
  82	void *pgmap_addr;
  83};
  84
  85struct segment_info {
  86	struct list_head lh;
  87	char segment_name[DCSS_BUS_ID_SIZE];
  88	unsigned long start;
  89	unsigned long end;
  90	int segment_type;
  91};
  92
  93static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  94				  size_t count);
  95static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  96				  size_t count);
  97
  98static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  99static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
 100
 101static struct device *dcssblk_root_dev;
 102
 103static LIST_HEAD(dcssblk_devices);
 104static struct rw_semaphore dcssblk_devices_sem;
 105
 106/*
 107 * release function for segment device.
 108 */
 109static void
 110dcssblk_release_segment(struct device *dev)
 111{
 112	struct dcssblk_dev_info *dev_info;
 113	struct segment_info *entry, *temp;
 114
 115	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 116	list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 117		list_del(&entry->lh);
 118		kfree(entry);
 119	}
 120	kfree(dev_info);
 121	module_put(THIS_MODULE);
 122}
 123
 124/*
 125 * get a minor number. needs to be called with
 126 * down_write(&dcssblk_devices_sem) and the
 127 * device needs to be enqueued before the semaphore is
 128 * freed.
 129 */
 130static int
 131dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 132{
 133	int minor, found;
 134	struct dcssblk_dev_info *entry;
 135
 136	if (dev_info == NULL)
 137		return -EINVAL;
 138	for (minor = 0; minor < (1<<MINORBITS); minor++) {
 139		found = 0;
 140		// test if minor available
 141		list_for_each_entry(entry, &dcssblk_devices, lh)
 142			if (minor == entry->gd->first_minor)
 143				found++;
 144		if (!found) break; // got unused minor
 145	}
 146	if (found)
 147		return -EBUSY;
 148	dev_info->gd->first_minor = minor;
 149	return 0;
 150}
 151
 152/*
 153 * get the struct dcssblk_dev_info from dcssblk_devices
 154 * for the given name.
 155 * down_read(&dcssblk_devices_sem) must be held.
 156 */
 157static struct dcssblk_dev_info *
 158dcssblk_get_device_by_name(char *name)
 159{
 160	struct dcssblk_dev_info *entry;
 161
 162	list_for_each_entry(entry, &dcssblk_devices, lh) {
 163		if (!strcmp(name, entry->segment_name)) {
 164			return entry;
 165		}
 166	}
 167	return NULL;
 168}
 169
 170/*
 171 * get the struct segment_info from seg_list
 172 * for the given name.
 173 * down_read(&dcssblk_devices_sem) must be held.
 174 */
 175static struct segment_info *
 176dcssblk_get_segment_by_name(char *name)
 177{
 178	struct dcssblk_dev_info *dev_info;
 179	struct segment_info *entry;
 180
 181	list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 182		list_for_each_entry(entry, &dev_info->seg_list, lh) {
 183			if (!strcmp(name, entry->segment_name))
 184				return entry;
 185		}
 186	}
 187	return NULL;
 188}
 189
 190/*
 191 * get the highest address of the multi-segment block.
 192 */
 193static unsigned long
 194dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 195{
 196	unsigned long highest_addr;
 197	struct segment_info *entry;
 198
 199	highest_addr = 0;
 200	list_for_each_entry(entry, &dev_info->seg_list, lh) {
 201		if (highest_addr < entry->end)
 202			highest_addr = entry->end;
 203	}
 204	return highest_addr;
 205}
 206
 207/*
 208 * get the lowest address of the multi-segment block.
 209 */
 210static unsigned long
 211dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 212{
 213	int set_first;
 214	unsigned long lowest_addr;
 215	struct segment_info *entry;
 216
 217	set_first = 0;
 218	lowest_addr = 0;
 219	list_for_each_entry(entry, &dev_info->seg_list, lh) {
 220		if (set_first == 0) {
 221			lowest_addr = entry->start;
 222			set_first = 1;
 223		} else {
 224			if (lowest_addr > entry->start)
 225				lowest_addr = entry->start;
 226		}
 227	}
 228	return lowest_addr;
 229}
 230
 231/*
 232 * Check continuity of segments.
 233 */
 234static int
 235dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 236{
 237	int i, j, rc;
 238	struct segment_info *sort_list, *entry, temp;
 239
 240	if (dev_info->num_of_segments <= 1)
 241		return 0;
 242
 243	sort_list = kcalloc(dev_info->num_of_segments,
 244			    sizeof(struct segment_info),
 245			    GFP_KERNEL);
 246	if (sort_list == NULL)
 247		return -ENOMEM;
 248	i = 0;
 249	list_for_each_entry(entry, &dev_info->seg_list, lh) {
 250		memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 251		i++;
 252	}
 253
 254	/* sort segments */
 255	for (i = 0; i < dev_info->num_of_segments; i++)
 256		for (j = 0; j < dev_info->num_of_segments; j++)
 257			if (sort_list[j].start > sort_list[i].start) {
 258				memcpy(&temp, &sort_list[i],
 259					sizeof(struct segment_info));
 260				memcpy(&sort_list[i], &sort_list[j],
 261					sizeof(struct segment_info));
 262				memcpy(&sort_list[j], &temp,
 263					sizeof(struct segment_info));
 264			}
 265
 266	/* check continuity */
 267	for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 268		if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 269			pr_err("Adjacent DCSSs %s and %s are not "
 270			       "contiguous\n", sort_list[i].segment_name,
 271			       sort_list[i+1].segment_name);
 272			rc = -EINVAL;
 273			goto out;
 274		}
 275		/* EN and EW are allowed in a block device */
 276		if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 277			if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 278				(sort_list[i].segment_type == SEG_TYPE_ER) ||
 279				!(sort_list[i+1].segment_type &
 280				SEGMENT_EXCLUSIVE) ||
 281				(sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 282				pr_err("DCSS %s and DCSS %s have "
 283				       "incompatible types\n",
 284				       sort_list[i].segment_name,
 285				       sort_list[i+1].segment_name);
 286				rc = -EINVAL;
 287				goto out;
 288			}
 289		}
 290	}
 291	rc = 0;
 292out:
 293	kfree(sort_list);
 294	return rc;
 295}
 296
 297/*
 298 * Load a segment
 299 */
 300static int
 301dcssblk_load_segment(char *name, struct segment_info **seg_info)
 302{
 303	int rc;
 304
 305	/* already loaded? */
 306	down_read(&dcssblk_devices_sem);
 307	*seg_info = dcssblk_get_segment_by_name(name);
 308	up_read(&dcssblk_devices_sem);
 309	if (*seg_info != NULL)
 310		return -EEXIST;
 311
 312	/* get a struct segment_info */
 313	*seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 314	if (*seg_info == NULL)
 315		return -ENOMEM;
 316
 317	strscpy((*seg_info)->segment_name, name);
 318
 319	/* load the segment */
 320	rc = segment_load(name, SEGMENT_SHARED,
 321			&(*seg_info)->start, &(*seg_info)->end);
 322	if (rc < 0) {
 323		segment_warning(rc, (*seg_info)->segment_name);
 324		kfree(*seg_info);
 325	} else {
 326		INIT_LIST_HEAD(&(*seg_info)->lh);
 327		(*seg_info)->segment_type = rc;
 328	}
 329	return rc;
 330}
 331
 332/*
 333 * device attribute for switching shared/nonshared (exclusive)
 334 * operation (show + store)
 335 */
 336static ssize_t
 337dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 338{
 339	struct dcssblk_dev_info *dev_info;
 340
 341	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 342	return sysfs_emit(buf, dev_info->is_shared ? "1\n" : "0\n");
 343}
 344
 345static ssize_t
 346dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 347{
 348	struct dcssblk_dev_info *dev_info;
 349	struct segment_info *entry, *temp;
 350	int rc;
 351
 352	if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 353		return -EINVAL;
 354	down_write(&dcssblk_devices_sem);
 355	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 356	if (atomic_read(&dev_info->use_count)) {
 357		rc = -EBUSY;
 358		goto out;
 359	}
 360	if (inbuf[0] == '1') {
 361		/* reload segments in shared mode */
 362		list_for_each_entry(entry, &dev_info->seg_list, lh) {
 363			rc = segment_modify_shared(entry->segment_name,
 364						SEGMENT_SHARED);
 365			if (rc < 0) {
 366				BUG_ON(rc == -EINVAL);
 367				if (rc != -EAGAIN)
 368					goto removeseg;
 369			}
 370		}
 371		dev_info->is_shared = 1;
 372		switch (dev_info->segment_type) {
 373		case SEG_TYPE_SR:
 374		case SEG_TYPE_ER:
 375		case SEG_TYPE_SC:
 376			set_disk_ro(dev_info->gd, 1);
 377		}
 378	} else if (inbuf[0] == '0') {
 379		/* reload segments in exclusive mode */
 380		if (dev_info->segment_type == SEG_TYPE_SC) {
 381			pr_err("DCSS %s is of type SC and cannot be "
 382			       "loaded as exclusive-writable\n",
 383			       dev_info->segment_name);
 384			rc = -EINVAL;
 385			goto out;
 386		}
 387		list_for_each_entry(entry, &dev_info->seg_list, lh) {
 388			rc = segment_modify_shared(entry->segment_name,
 389						   SEGMENT_EXCLUSIVE);
 390			if (rc < 0) {
 391				BUG_ON(rc == -EINVAL);
 392				if (rc != -EAGAIN)
 393					goto removeseg;
 394			}
 395		}
 396		dev_info->is_shared = 0;
 397		set_disk_ro(dev_info->gd, 0);
 398	} else {
 399		rc = -EINVAL;
 400		goto out;
 401	}
 402	rc = count;
 403	goto out;
 404
 405removeseg:
 406	pr_err("DCSS device %s is removed after a failed access mode "
 407	       "change\n", dev_info->segment_name);
 408	temp = entry;
 409	list_for_each_entry(entry, &dev_info->seg_list, lh) {
 410		if (entry != temp)
 411			segment_unload(entry->segment_name);
 412	}
 413	list_del(&dev_info->lh);
 414	up_write(&dcssblk_devices_sem);
 415
 416	dax_remove_host(dev_info->gd);
 417	kill_dax(dev_info->dax_dev);
 418	put_dax(dev_info->dax_dev);
 419	if (dev_info->pgmap_addr)
 420		devm_memunmap_pages(&dev_info->dev, &dev_info->pgmap);
 421	del_gendisk(dev_info->gd);
 422	put_disk(dev_info->gd);
 423
 424	if (device_remove_file_self(dev, attr)) {
 425		device_unregister(dev);
 426		put_device(dev);
 427	}
 428	return rc;
 429out:
 430	up_write(&dcssblk_devices_sem);
 431	return rc;
 432}
 433static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 434		   dcssblk_shared_store);
 435
 436/*
 437 * device attribute for save operation on current copy
 438 * of the segment. If the segment is busy, saving will
 439 * become pending until it gets released, which can be
 440 * undone by storing a non-true value to this entry.
 441 * (show + store)
 442 */
 443static ssize_t
 444dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 445{
 446	struct dcssblk_dev_info *dev_info;
 447
 448	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 449	return sysfs_emit(buf, dev_info->save_pending ? "1\n" : "0\n");
 450}
 451
 452static ssize_t
 453dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 454{
 455	struct dcssblk_dev_info *dev_info;
 456	struct segment_info *entry;
 457
 458	if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 459		return -EINVAL;
 460	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 461
 462	down_write(&dcssblk_devices_sem);
 463	if (inbuf[0] == '1') {
 464		if (atomic_read(&dev_info->use_count) == 0) {
 465			// device is idle => we save immediately
 466			pr_info("All DCSSs that map to device %s are "
 467				"saved\n", dev_info->segment_name);
 468			list_for_each_entry(entry, &dev_info->seg_list, lh) {
 469				if (entry->segment_type == SEG_TYPE_EN ||
 470				    entry->segment_type == SEG_TYPE_SN)
 471					pr_warn("DCSS %s is of type SN or EN"
 472						" and cannot be saved\n",
 473						entry->segment_name);
 474				else
 475					segment_save(entry->segment_name);
 476			}
 477		}  else {
 478			// device is busy => we save it when it becomes
 479			// idle in dcssblk_release
 480			pr_info("Device %s is in use, its DCSSs will be "
 481				"saved when it becomes idle\n",
 482				dev_info->segment_name);
 483			dev_info->save_pending = 1;
 484		}
 485	} else if (inbuf[0] == '0') {
 486		if (dev_info->save_pending) {
 487			// device is busy & the user wants to undo his save
 488			// request
 489			dev_info->save_pending = 0;
 490			pr_info("A pending save request for device %s "
 491				"has been canceled\n",
 492				dev_info->segment_name);
 493		}
 494	} else {
 495		up_write(&dcssblk_devices_sem);
 496		return -EINVAL;
 497	}
 498	up_write(&dcssblk_devices_sem);
 499	return count;
 500}
 501static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 502		   dcssblk_save_store);
 503
 504/*
 505 * device attribute for showing all segments in a device
 506 */
 507static ssize_t
 508dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 509		char *buf)
 510{
 511	struct dcssblk_dev_info *dev_info;
 512	struct segment_info *entry;
 513	int i;
 514
 515	i = 0;
 516	down_read(&dcssblk_devices_sem);
 517	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 518	list_for_each_entry(entry, &dev_info->seg_list, lh)
 519		i += sysfs_emit_at(buf, i, "%s\n", entry->segment_name);
 520	up_read(&dcssblk_devices_sem);
 521	return i;
 522}
 523static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 524
 525static struct attribute *dcssblk_dev_attrs[] = {
 526	&dev_attr_shared.attr,
 527	&dev_attr_save.attr,
 528	&dev_attr_seglist.attr,
 529	NULL,
 530};
 531static struct attribute_group dcssblk_dev_attr_group = {
 532	.attrs = dcssblk_dev_attrs,
 533};
 534static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 535	&dcssblk_dev_attr_group,
 536	NULL,
 537};
 538
 539static int dcssblk_setup_dax(struct dcssblk_dev_info *dev_info)
 540{
 541	struct dax_device *dax_dev;
 542
 543	dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
 544	if (IS_ERR(dax_dev))
 545		return PTR_ERR(dax_dev);
 546	set_dax_synchronous(dax_dev);
 547	dev_info->dax_dev = dax_dev;
 548	return dax_add_host(dev_info->dax_dev, dev_info->gd);
 549}
 550
 551/*
 552 * device attribute for adding devices
 553 */
 554static ssize_t
 555dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 556{
 557	struct queue_limits lim = {
 558		.logical_block_size	= 4096,
 559		.features		= BLK_FEAT_DAX,
 560	};
 561	int rc, i, j, num_of_segments;
 562	struct dcssblk_dev_info *dev_info;
 563	struct segment_info *seg_info, *temp;
 564	char *local_buf;
 565	void *addr;
 566	unsigned long seg_byte_size;
 567
 568	dev_info = NULL;
 569	seg_info = NULL;
 570	if (dev != dcssblk_root_dev) {
 571		rc = -EINVAL;
 572		goto out_nobuf;
 573	}
 574	if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 575		rc = -ENAMETOOLONG;
 576		goto out_nobuf;
 577	}
 578
 579	local_buf = kmalloc(count + 1, GFP_KERNEL);
 580	if (local_buf == NULL) {
 581		rc = -ENOMEM;
 582		goto out_nobuf;
 583	}
 584
 585	/*
 586	 * parse input
 587	 */
 588	num_of_segments = 0;
 589	for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 590		for (j = i; j < count &&
 591			(buf[j] != ':') &&
 592			(buf[j] != '\0') &&
 593			(buf[j] != '\n'); j++) {
 594			local_buf[j-i] = toupper(buf[j]);
 595		}
 596		local_buf[j-i] = '\0';
 597		if (((j - i) == 0) || ((j - i) > 8)) {
 598			rc = -ENAMETOOLONG;
 599			goto seg_list_del;
 600		}
 601
 602		rc = dcssblk_load_segment(local_buf, &seg_info);
 603		if (rc < 0)
 604			goto seg_list_del;
 605		/*
 606		 * get a struct dcssblk_dev_info
 607		 */
 608		if (num_of_segments == 0) {
 609			dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 610					GFP_KERNEL);
 611			if (dev_info == NULL) {
 612				rc = -ENOMEM;
 613				goto out;
 614			}
 615			strscpy(dev_info->segment_name, local_buf);
 616			dev_info->segment_type = seg_info->segment_type;
 617			INIT_LIST_HEAD(&dev_info->seg_list);
 618		}
 619		list_add_tail(&seg_info->lh, &dev_info->seg_list);
 620		num_of_segments++;
 621		i = j;
 622
 623		if ((buf[j] == '\0') || (buf[j] == '\n'))
 624			break;
 625	}
 626
 627	/* no trailing colon at the end of the input */
 628	if ((i > 0) && (buf[i-1] == ':')) {
 629		rc = -ENAMETOOLONG;
 630		goto seg_list_del;
 631	}
 632	strscpy(local_buf, buf, i + 1);
 633	dev_info->num_of_segments = num_of_segments;
 634	rc = dcssblk_is_continuous(dev_info);
 635	if (rc < 0)
 636		goto seg_list_del;
 637
 638	dev_info->start = dcssblk_find_lowest_addr(dev_info);
 639	dev_info->end = dcssblk_find_highest_addr(dev_info);
 640
 641	dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 642	dev_info->dev.release = dcssblk_release_segment;
 643	dev_info->dev.groups = dcssblk_dev_attr_groups;
 644	INIT_LIST_HEAD(&dev_info->lh);
 645	dev_info->gd = blk_alloc_disk(&lim, NUMA_NO_NODE);
 646	if (IS_ERR(dev_info->gd)) {
 647		rc = PTR_ERR(dev_info->gd);
 648		goto seg_list_del;
 649	}
 650	dev_info->gd->major = dcssblk_major;
 651	dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
 652	dev_info->gd->fops = &dcssblk_devops;
 653	dev_info->gd->private_data = dev_info;
 654	dev_info->gd->flags |= GENHD_FL_NO_PART;
 655
 656	seg_byte_size = (dev_info->end - dev_info->start + 1);
 657	set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 658	pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 659		"sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 660
 661	dev_info->save_pending = 0;
 662	dev_info->is_shared = 1;
 663	dev_info->dev.parent = dcssblk_root_dev;
 664
 665	/*
 666	 *get minor, add to list
 667	 */
 668	down_write(&dcssblk_devices_sem);
 669	if (dcssblk_get_segment_by_name(local_buf)) {
 670		rc = -EEXIST;
 671		goto release_gd;
 672	}
 673	rc = dcssblk_assign_free_minor(dev_info);
 674	if (rc)
 675		goto release_gd;
 676	scnprintf(dev_info->gd->disk_name, sizeof(dev_info->gd->disk_name),
 677		  "dcssblk%d", dev_info->gd->first_minor);
 678	list_add_tail(&dev_info->lh, &dcssblk_devices);
 679
 680	if (!try_module_get(THIS_MODULE)) {
 681		rc = -ENODEV;
 682		goto dev_list_del;
 683	}
 684	/*
 685	 * register the device
 686	 */
 687	rc = device_register(&dev_info->dev);
 688	if (rc)
 689		goto put_dev;
 690
 691	if (!IS_ALIGNED(dev_info->start, SUBSECTION_SIZE) ||
 692	    !IS_ALIGNED(dev_info->end + 1, SUBSECTION_SIZE)) {
 693		pr_info("DCSS %s is not aligned to %lu bytes, DAX support disabled\n",
 694			local_buf, SUBSECTION_SIZE);
 695	} else {
 696		dev_info->pgmap.type		= MEMORY_DEVICE_FS_DAX;
 697		dev_info->pgmap.range.start	= dev_info->start;
 698		dev_info->pgmap.range.end	= dev_info->end;
 699		dev_info->pgmap.nr_range	= 1;
 700		addr = devm_memremap_pages(&dev_info->dev, &dev_info->pgmap);
 701		if (IS_ERR(addr)) {
 702			rc = PTR_ERR(addr);
 703			goto put_dev;
 704		}
 705		dev_info->pgmap_addr = addr;
 706		rc = dcssblk_setup_dax(dev_info);
 707		if (rc)
 708			goto out_dax;
 709		pr_info("DAX support enabled for DCSS %s\n", local_buf);
 710	}
 711
 712	get_device(&dev_info->dev);
 713	rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 714	if (rc)
 715		goto out_dax_host;
 716
 717	switch (dev_info->segment_type) {
 718		case SEG_TYPE_SR:
 719		case SEG_TYPE_ER:
 720		case SEG_TYPE_SC:
 721			set_disk_ro(dev_info->gd,1);
 722			break;
 723		default:
 724			set_disk_ro(dev_info->gd,0);
 725			break;
 726	}
 727	up_write(&dcssblk_devices_sem);
 728	rc = count;
 729	goto out;
 730
 731out_dax_host:
 732	put_device(&dev_info->dev);
 733	dax_remove_host(dev_info->gd);
 734out_dax:
 735	kill_dax(dev_info->dax_dev);
 736	put_dax(dev_info->dax_dev);
 737	if (dev_info->pgmap_addr)
 738		devm_memunmap_pages(&dev_info->dev, &dev_info->pgmap);
 739put_dev:
 740	list_del(&dev_info->lh);
 741	put_disk(dev_info->gd);
 742	list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 743		segment_unload(seg_info->segment_name);
 744	}
 745	put_device(&dev_info->dev);
 746	up_write(&dcssblk_devices_sem);
 747	goto out;
 748dev_list_del:
 749	list_del(&dev_info->lh);
 750release_gd:
 751	put_disk(dev_info->gd);
 752	up_write(&dcssblk_devices_sem);
 753seg_list_del:
 754	if (dev_info == NULL)
 755		goto out;
 756	list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 757		list_del(&seg_info->lh);
 758		segment_unload(seg_info->segment_name);
 759		kfree(seg_info);
 760	}
 761	kfree(dev_info);
 762out:
 763	kfree(local_buf);
 764out_nobuf:
 765	return rc;
 766}
 767
 768/*
 769 * device attribute for removing devices
 770 */
 771static ssize_t
 772dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 773{
 774	struct dcssblk_dev_info *dev_info;
 775	struct segment_info *entry;
 776	int rc, i;
 777	char *local_buf;
 778
 779	if (dev != dcssblk_root_dev) {
 780		return -EINVAL;
 781	}
 782	local_buf = kmalloc(count + 1, GFP_KERNEL);
 783	if (local_buf == NULL) {
 784		return -ENOMEM;
 785	}
 786	/*
 787	 * parse input
 788	 */
 789	for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 790		local_buf[i] = toupper(buf[i]);
 791	}
 792	local_buf[i] = '\0';
 793	if ((i == 0) || (i > 8)) {
 794		rc = -ENAMETOOLONG;
 795		goto out_buf;
 796	}
 797
 798	down_write(&dcssblk_devices_sem);
 799	dev_info = dcssblk_get_device_by_name(local_buf);
 800	if (dev_info == NULL) {
 801		up_write(&dcssblk_devices_sem);
 802		pr_warn("Device %s cannot be removed because it is not a known device\n",
 803			local_buf);
 804		rc = -ENODEV;
 805		goto out_buf;
 806	}
 807	if (atomic_read(&dev_info->use_count) != 0) {
 808		up_write(&dcssblk_devices_sem);
 809		pr_warn("Device %s cannot be removed while it is in use\n",
 810			local_buf);
 811		rc = -EBUSY;
 812		goto out_buf;
 813	}
 814
 815	list_del(&dev_info->lh);
 816	/* unload all related segments */
 817	list_for_each_entry(entry, &dev_info->seg_list, lh)
 818		segment_unload(entry->segment_name);
 819	up_write(&dcssblk_devices_sem);
 820
 821	dax_remove_host(dev_info->gd);
 822	kill_dax(dev_info->dax_dev);
 823	put_dax(dev_info->dax_dev);
 824	if (dev_info->pgmap_addr)
 825		devm_memunmap_pages(&dev_info->dev, &dev_info->pgmap);
 826	del_gendisk(dev_info->gd);
 827	put_disk(dev_info->gd);
 828
 829	device_unregister(&dev_info->dev);
 830	put_device(&dev_info->dev);
 831
 832	rc = count;
 833out_buf:
 834	kfree(local_buf);
 835	return rc;
 836}
 837
 838static int
 839dcssblk_open(struct gendisk *disk, blk_mode_t mode)
 840{
 841	struct dcssblk_dev_info *dev_info = disk->private_data;
 842	int rc;
 843
 844	if (NULL == dev_info) {
 845		rc = -ENODEV;
 846		goto out;
 847	}
 848	atomic_inc(&dev_info->use_count);
 849	rc = 0;
 850out:
 851	return rc;
 852}
 853
 854static void
 855dcssblk_release(struct gendisk *disk)
 856{
 857	struct dcssblk_dev_info *dev_info = disk->private_data;
 858	struct segment_info *entry;
 859
 860	if (!dev_info) {
 861		WARN_ON(1);
 862		return;
 863	}
 864	down_write(&dcssblk_devices_sem);
 865	if (atomic_dec_and_test(&dev_info->use_count)
 866	    && (dev_info->save_pending)) {
 867		pr_info("Device %s has become idle and is being saved "
 868			"now\n", dev_info->segment_name);
 869		list_for_each_entry(entry, &dev_info->seg_list, lh) {
 870			if (entry->segment_type == SEG_TYPE_EN ||
 871			    entry->segment_type == SEG_TYPE_SN)
 872				pr_warn("DCSS %s is of type SN or EN and cannot"
 873					" be saved\n", entry->segment_name);
 874			else
 875				segment_save(entry->segment_name);
 876		}
 877		dev_info->save_pending = 0;
 878	}
 879	up_write(&dcssblk_devices_sem);
 880}
 881
 882static void
 883dcssblk_submit_bio(struct bio *bio)
 884{
 885	struct dcssblk_dev_info *dev_info;
 886	struct bio_vec bvec;
 887	struct bvec_iter iter;
 888	unsigned long index;
 889	void *page_addr;
 890	unsigned long source_addr;
 891	unsigned long bytes_done;
 892
 893	bytes_done = 0;
 894	dev_info = bio->bi_bdev->bd_disk->private_data;
 895	if (dev_info == NULL)
 896		goto fail;
 897	if (!IS_ALIGNED(bio->bi_iter.bi_sector, 8) ||
 898	    !IS_ALIGNED(bio->bi_iter.bi_size, PAGE_SIZE))
 899		/* Request is not page-aligned. */
 900		goto fail;
 901	/* verify data transfer direction */
 902	if (dev_info->is_shared) {
 903		switch (dev_info->segment_type) {
 904		case SEG_TYPE_SR:
 905		case SEG_TYPE_ER:
 906		case SEG_TYPE_SC:
 907			/* cannot write to these segments */
 908			if (bio_data_dir(bio) == WRITE) {
 909				pr_warn("Writing to %s failed because it is a read-only device\n",
 910					dev_name(&dev_info->dev));
 911				goto fail;
 912			}
 913		}
 914	}
 915
 916	index = (bio->bi_iter.bi_sector >> 3);
 917	bio_for_each_segment(bvec, bio, iter) {
 918		page_addr = bvec_virt(&bvec);
 919		source_addr = dev_info->start + (index<<12) + bytes_done;
 920		if (unlikely(!IS_ALIGNED((unsigned long)page_addr, PAGE_SIZE) ||
 921			     !IS_ALIGNED(bvec.bv_len, PAGE_SIZE)))
 922			// More paranoia.
 923			goto fail;
 924		if (bio_data_dir(bio) == READ)
 925			memcpy(page_addr, __va(source_addr), bvec.bv_len);
 926		else
 927			memcpy(__va(source_addr), page_addr, bvec.bv_len);
 928		bytes_done += bvec.bv_len;
 929	}
 930	bio_endio(bio);
 931	return;
 932fail:
 933	bio_io_error(bio);
 934}
 935
 936static long
 937__dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 938		long nr_pages, void **kaddr, unsigned long *pfn)
 939{
 940	resource_size_t offset = pgoff * PAGE_SIZE;
 941	unsigned long dev_sz;
 942
 943	dev_sz = dev_info->end - dev_info->start + 1;
 944	if (kaddr)
 945		*kaddr = __va(dev_info->start + offset);
 946	if (pfn)
 947		*pfn = PFN_DOWN(dev_info->start + offset);
 948
 949	return (dev_sz - offset) / PAGE_SIZE;
 950}
 951
 952static long
 953dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 954		long nr_pages, enum dax_access_mode mode, void **kaddr,
 955		unsigned long *pfn)
 956{
 957	struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 958
 959	return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 960}
 961
 962static void
 963dcssblk_check_params(void)
 964{
 965	int rc, i, j, k;
 966	char buf[DCSSBLK_PARM_LEN + 1];
 967	struct dcssblk_dev_info *dev_info;
 968
 969	for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 970	     i++) {
 971		for (j = i; (j < DCSSBLK_PARM_LEN) &&
 972			    (dcssblk_segments[j] != ',')  &&
 973			    (dcssblk_segments[j] != '\0') &&
 974			    (dcssblk_segments[j] != '('); j++)
 975		{
 976			buf[j-i] = dcssblk_segments[j];
 977		}
 978		buf[j-i] = '\0';
 979		rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 980		if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 981			for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 982				buf[k] = toupper(buf[k]);
 983			buf[k] = '\0';
 984			if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 985				down_read(&dcssblk_devices_sem);
 986				dev_info = dcssblk_get_device_by_name(buf);
 987				up_read(&dcssblk_devices_sem);
 988				if (dev_info)
 989					dcssblk_shared_store(&dev_info->dev,
 990							     NULL, "0\n", 2);
 991			}
 992		}
 993		while ((dcssblk_segments[j] != ',') &&
 994		       (dcssblk_segments[j] != '\0'))
 995		{
 996			j++;
 997		}
 998		if (dcssblk_segments[j] == '\0')
 999			break;
1000		i = j;
1001	}
1002}
1003
1004/*
1005 * The init/exit functions.
1006 */
1007static void __exit
1008dcssblk_exit(void)
1009{
1010	root_device_unregister(dcssblk_root_dev);
1011	unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1012}
1013
1014static int __init
1015dcssblk_init(void)
1016{
1017	int rc;
1018
1019	dcssblk_root_dev = root_device_register("dcssblk");
1020	if (IS_ERR(dcssblk_root_dev))
1021		return PTR_ERR(dcssblk_root_dev);
1022	rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1023	if (rc)
1024		goto out_root;
1025	rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1026	if (rc)
1027		goto out_root;
1028	rc = register_blkdev(0, DCSSBLK_NAME);
1029	if (rc < 0)
1030		goto out_root;
1031	dcssblk_major = rc;
1032	init_rwsem(&dcssblk_devices_sem);
1033
1034	dcssblk_check_params();
1035	return 0;
1036
1037out_root:
1038	root_device_unregister(dcssblk_root_dev);
1039
1040	return rc;
1041}
1042
1043module_init(dcssblk_init);
1044module_exit(dcssblk_exit);
1045
1046module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1047MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1048		 "comma-separated list, names in each set separated "
1049		 "by commas are separated by colons, each set contains "
1050		 "names of contiguous segments and each name max. 8 chars.\n"
1051		 "Adding \"(local)\" to the end of each set equals echoing 0 "
1052		 "to /sys/devices/dcssblk/<device name>/shared after loading "
1053		 "the contiguous segments - \n"
1054		 "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1055
1056MODULE_DESCRIPTION("S/390 block driver for DCSS memory");
1057MODULE_LICENSE("GPL");