blob: c548a5a6c1a009881a4912cccfe66988eca61758 [file] [log] [blame]
Thomas Gleixner09c434b2019-05-19 13:08:20 +01001// SPDX-License-Identifier: GPL-2.0-only
Nick Piggin9db55792008-02-08 04:19:49 -08002/*
3 * Ram backed block device driver.
4 *
5 * Copyright (C) 2007 Nick Piggin
6 * Copyright (C) 2007 Novell Inc.
7 *
8 * Parts derived from drivers/block/rd.c, and drivers/block/loop.c, copyright
9 * of their respective owners.
10 */
11
12#include <linux/init.h>
Bart Van Assche287f3ca2017-07-10 15:51:10 -070013#include <linux/initrd.h>
Nick Piggin9db55792008-02-08 04:19:49 -080014#include <linux/module.h>
15#include <linux/moduleparam.h>
16#include <linux/major.h>
17#include <linux/blkdev.h>
18#include <linux/bio.h>
19#include <linux/highmem.h>
Arnd Bergmann2a48fc02010-06-02 14:28:52 +020020#include <linux/mutex.h>
Nick Piggin9db55792008-02-08 04:19:49 -080021#include <linux/radix-tree.h>
Al Viroff01bb42011-09-16 02:31:11 -040022#include <linux/fs.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090023#include <linux/slab.h>
Minchan Kim23c47d22017-11-15 17:33:00 -080024#include <linux/backing-dev.h>
Nick Piggin9db55792008-02-08 04:19:49 -080025
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -080026#include <linux/uaccess.h>
Nick Piggin9db55792008-02-08 04:19:49 -080027
Nick Piggin9db55792008-02-08 04:19:49 -080028#define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
29#define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT)
30
31/*
32 * Each block ramdisk device has a radix_tree brd_pages of pages that stores
33 * the pages containing the block device's contents. A brd page's ->index is
34 * its offset in PAGE_SIZE units. This is similar to, but in no way connected
35 * with, the kernel's pagecache or buffer cache (which sit above our block
36 * device).
37 */
38struct brd_device {
39 int brd_number;
Nick Piggin9db55792008-02-08 04:19:49 -080040
41 struct request_queue *brd_queue;
42 struct gendisk *brd_disk;
43 struct list_head brd_list;
44
45 /*
46 * Backing store of pages and lock to protect it. This is the contents
47 * of the block device.
48 */
49 spinlock_t brd_lock;
50 struct radix_tree_root brd_pages;
51};
52
53/*
54 * Look up and return a brd's page for a given sector.
55 */
56static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
57{
58 pgoff_t idx;
59 struct page *page;
60
61 /*
62 * The page lifetime is protected by the fact that we have opened the
63 * device node -- brd pages will never be deleted under us, so we
64 * don't need any further locking or refcounting.
65 *
66 * This is strictly true for the radix-tree nodes as well (ie. we
67 * don't actually need the rcu_read_lock()), however that is not a
68 * documented feature of the radix-tree API so it is better to be
69 * safe here (we don't have total exclusion from radix tree updates
70 * here, only deletes).
71 */
72 rcu_read_lock();
73 idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */
74 page = radix_tree_lookup(&brd->brd_pages, idx);
75 rcu_read_unlock();
76
77 BUG_ON(page && page->index != idx);
78
79 return page;
80}
81
82/*
83 * Look up and return a brd's page for a given sector.
84 * If one does not exist, allocate an empty page, and insert that. Then
85 * return it.
86 */
87static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
88{
89 pgoff_t idx;
90 struct page *page;
Nick Piggin75acb9c2008-02-08 04:19:50 -080091 gfp_t gfp_flags;
Nick Piggin9db55792008-02-08 04:19:49 -080092
93 page = brd_lookup_page(brd, sector);
94 if (page)
95 return page;
96
97 /*
98 * Must use NOIO because we don't want to recurse back into the
99 * block or filesystem layers from page reclaim.
100 */
Hou Taof6b50162019-04-22 21:23:21 +0800101 gfp_flags = GFP_NOIO | __GFP_ZERO | __GFP_HIGHMEM;
Petr Tesarik26defe32008-04-22 05:36:52 +0200102 page = alloc_page(gfp_flags);
Nick Piggin9db55792008-02-08 04:19:49 -0800103 if (!page)
104 return NULL;
105
106 if (radix_tree_preload(GFP_NOIO)) {
107 __free_page(page);
108 return NULL;
109 }
110
111 spin_lock(&brd->brd_lock);
112 idx = sector >> PAGE_SECTORS_SHIFT;
Brian Behlendorfdfd20b22013-05-24 15:55:28 -0700113 page->index = idx;
Nick Piggin9db55792008-02-08 04:19:49 -0800114 if (radix_tree_insert(&brd->brd_pages, idx, page)) {
115 __free_page(page);
116 page = radix_tree_lookup(&brd->brd_pages, idx);
117 BUG_ON(!page);
118 BUG_ON(page->index != idx);
Brian Behlendorfdfd20b22013-05-24 15:55:28 -0700119 }
Nick Piggin9db55792008-02-08 04:19:49 -0800120 spin_unlock(&brd->brd_lock);
121
122 radix_tree_preload_end();
123
124 return page;
125}
126
127/*
128 * Free all backing store pages and radix tree. This must only be called when
129 * there are no other users of the device.
130 */
131#define FREE_BATCH 16
132static void brd_free_pages(struct brd_device *brd)
133{
134 unsigned long pos = 0;
135 struct page *pages[FREE_BATCH];
136 int nr_pages;
137
138 do {
139 int i;
140
141 nr_pages = radix_tree_gang_lookup(&brd->brd_pages,
142 (void **)pages, pos, FREE_BATCH);
143
144 for (i = 0; i < nr_pages; i++) {
145 void *ret;
146
147 BUG_ON(pages[i]->index < pos);
148 pos = pages[i]->index;
149 ret = radix_tree_delete(&brd->brd_pages, pos);
150 BUG_ON(!ret || ret != pages[i]);
151 __free_page(pages[i]);
152 }
153
154 pos++;
155
156 /*
Mikulas Patocka936b33f2019-05-09 12:51:27 -0600157 * It takes 3.4 seconds to remove 80GiB ramdisk.
158 * So, we need cond_resched to avoid stalling the CPU.
159 */
160 cond_resched();
161
162 /*
Nick Piggin9db55792008-02-08 04:19:49 -0800163 * This assumes radix_tree_gang_lookup always returns as
164 * many pages as possible. If the radix-tree code changes,
165 * so will this have to.
166 */
167 } while (nr_pages == FREE_BATCH);
168}
169
170/*
171 * copy_to_brd_setup must be called before copy_to_brd. It may sleep.
172 */
173static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n)
174{
175 unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
176 size_t copy;
177
178 copy = min_t(size_t, n, PAGE_SIZE - offset);
179 if (!brd_insert_page(brd, sector))
Matthew Wilcox96f8d8e2014-06-04 16:07:50 -0700180 return -ENOSPC;
Nick Piggin9db55792008-02-08 04:19:49 -0800181 if (copy < n) {
182 sector += copy >> SECTOR_SHIFT;
183 if (!brd_insert_page(brd, sector))
Matthew Wilcox96f8d8e2014-06-04 16:07:50 -0700184 return -ENOSPC;
Nick Piggin9db55792008-02-08 04:19:49 -0800185 }
186 return 0;
187}
188
189/*
190 * Copy n bytes from src to the brd starting at sector. Does not sleep.
191 */
192static void copy_to_brd(struct brd_device *brd, const void *src,
193 sector_t sector, size_t n)
194{
195 struct page *page;
196 void *dst;
197 unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
198 size_t copy;
199
200 copy = min_t(size_t, n, PAGE_SIZE - offset);
201 page = brd_lookup_page(brd, sector);
202 BUG_ON(!page);
203
Cong Wangcfd80052011-11-25 23:14:18 +0800204 dst = kmap_atomic(page);
Nick Piggin9db55792008-02-08 04:19:49 -0800205 memcpy(dst + offset, src, copy);
Cong Wangcfd80052011-11-25 23:14:18 +0800206 kunmap_atomic(dst);
Nick Piggin9db55792008-02-08 04:19:49 -0800207
208 if (copy < n) {
209 src += copy;
210 sector += copy >> SECTOR_SHIFT;
211 copy = n - copy;
212 page = brd_lookup_page(brd, sector);
213 BUG_ON(!page);
214
Cong Wangcfd80052011-11-25 23:14:18 +0800215 dst = kmap_atomic(page);
Nick Piggin9db55792008-02-08 04:19:49 -0800216 memcpy(dst, src, copy);
Cong Wangcfd80052011-11-25 23:14:18 +0800217 kunmap_atomic(dst);
Nick Piggin9db55792008-02-08 04:19:49 -0800218 }
219}
220
221/*
222 * Copy n bytes to dst from the brd starting at sector. Does not sleep.
223 */
224static void copy_from_brd(void *dst, struct brd_device *brd,
225 sector_t sector, size_t n)
226{
227 struct page *page;
228 void *src;
229 unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
230 size_t copy;
231
232 copy = min_t(size_t, n, PAGE_SIZE - offset);
233 page = brd_lookup_page(brd, sector);
234 if (page) {
Cong Wangcfd80052011-11-25 23:14:18 +0800235 src = kmap_atomic(page);
Nick Piggin9db55792008-02-08 04:19:49 -0800236 memcpy(dst, src + offset, copy);
Cong Wangcfd80052011-11-25 23:14:18 +0800237 kunmap_atomic(src);
Nick Piggin9db55792008-02-08 04:19:49 -0800238 } else
239 memset(dst, 0, copy);
240
241 if (copy < n) {
242 dst += copy;
243 sector += copy >> SECTOR_SHIFT;
244 copy = n - copy;
245 page = brd_lookup_page(brd, sector);
246 if (page) {
Cong Wangcfd80052011-11-25 23:14:18 +0800247 src = kmap_atomic(page);
Nick Piggin9db55792008-02-08 04:19:49 -0800248 memcpy(dst, src, copy);
Cong Wangcfd80052011-11-25 23:14:18 +0800249 kunmap_atomic(src);
Nick Piggin9db55792008-02-08 04:19:49 -0800250 } else
251 memset(dst, 0, copy);
252 }
253}
254
255/*
256 * Process a single bvec of a bio.
257 */
258static int brd_do_bvec(struct brd_device *brd, struct page *page,
Tejun Heo3f289dc2018-07-18 04:47:36 -0700259 unsigned int len, unsigned int off, unsigned int op,
Nick Piggin9db55792008-02-08 04:19:49 -0800260 sector_t sector)
261{
262 void *mem;
263 int err = 0;
264
Tejun Heo3f289dc2018-07-18 04:47:36 -0700265 if (op_is_write(op)) {
Nick Piggin9db55792008-02-08 04:19:49 -0800266 err = copy_to_brd_setup(brd, sector, len);
267 if (err)
268 goto out;
269 }
270
Cong Wangcfd80052011-11-25 23:14:18 +0800271 mem = kmap_atomic(page);
Tejun Heo3f289dc2018-07-18 04:47:36 -0700272 if (!op_is_write(op)) {
Nick Piggin9db55792008-02-08 04:19:49 -0800273 copy_from_brd(mem + off, brd, sector, len);
274 flush_dcache_page(page);
Nick Pigginc2572f22009-04-15 10:32:07 +0200275 } else {
276 flush_dcache_page(page);
Nick Piggin9db55792008-02-08 04:19:49 -0800277 copy_to_brd(brd, mem + off, sector, len);
Nick Pigginc2572f22009-04-15 10:32:07 +0200278 }
Cong Wangcfd80052011-11-25 23:14:18 +0800279 kunmap_atomic(mem);
Nick Piggin9db55792008-02-08 04:19:49 -0800280
281out:
282 return err;
283}
284
Jens Axboedece1632015-11-05 10:41:16 -0700285static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
Nick Piggin9db55792008-02-08 04:19:49 -0800286{
Christoph Hellwig74d46992017-08-23 19:10:32 +0200287 struct brd_device *brd = bio->bi_disk->private_data;
Kent Overstreet79886132013-11-23 17:19:00 -0800288 struct bio_vec bvec;
Nick Piggin9db55792008-02-08 04:19:49 -0800289 sector_t sector;
Kent Overstreet79886132013-11-23 17:19:00 -0800290 struct bvec_iter iter;
Nick Piggin9db55792008-02-08 04:19:49 -0800291
Kent Overstreet4f024f32013-10-11 15:44:27 -0700292 sector = bio->bi_iter.bi_sector;
Christoph Hellwig74d46992017-08-23 19:10:32 +0200293 if (bio_end_sector(bio) > get_capacity(bio->bi_disk))
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200294 goto io_error;
Nick Piggin9db55792008-02-08 04:19:49 -0800295
Kent Overstreet79886132013-11-23 17:19:00 -0800296 bio_for_each_segment(bvec, bio, iter) {
297 unsigned int len = bvec.bv_len;
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200298 int err;
299
Jens Axboec11f0c02016-08-05 08:11:04 -0600300 err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
Tejun Heo3f289dc2018-07-18 04:47:36 -0700301 bio_op(bio), sector);
Nick Piggin9db55792008-02-08 04:19:49 -0800302 if (err)
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200303 goto io_error;
Nick Piggin9db55792008-02-08 04:19:49 -0800304 sector += len >> SECTOR_SHIFT;
305 }
306
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200307 bio_endio(bio);
Jens Axboedece1632015-11-05 10:41:16 -0700308 return BLK_QC_T_NONE;
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200309io_error:
310 bio_io_error(bio);
Jens Axboedece1632015-11-05 10:41:16 -0700311 return BLK_QC_T_NONE;
Nick Piggin9db55792008-02-08 04:19:49 -0800312}
313
Matthew Wilcoxa72132c2014-06-04 16:07:49 -0700314static int brd_rw_page(struct block_device *bdev, sector_t sector,
Tejun Heo3f289dc2018-07-18 04:47:36 -0700315 struct page *page, unsigned int op)
Matthew Wilcoxa72132c2014-06-04 16:07:49 -0700316{
317 struct brd_device *brd = bdev->bd_disk->private_data;
Huang Ying98cc0932017-09-06 16:22:27 -0700318 int err;
319
320 if (PageTransHuge(page))
321 return -ENOTSUPP;
Tejun Heo3f289dc2018-07-18 04:47:36 -0700322 err = brd_do_bvec(brd, page, PAGE_SIZE, 0, op, sector);
323 page_endio(page, op_is_write(op), err);
Matthew Wilcoxa72132c2014-06-04 16:07:49 -0700324 return err;
325}
326
Alexey Dobriyan83d5cde2009-09-21 17:01:13 -0700327static const struct block_device_operations brd_fops = {
Nick Piggin75acb9c2008-02-08 04:19:50 -0800328 .owner = THIS_MODULE,
Matthew Wilcoxa72132c2014-06-04 16:07:49 -0700329 .rw_page = brd_rw_page,
Nick Piggin9db55792008-02-08 04:19:49 -0800330};
331
332/*
333 * And now the modules code and kernel interface.
334 */
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200335static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT;
Joe Perches5657a812018-05-24 13:38:59 -0600336module_param(rd_nr, int, 0444);
Nick Piggin9db55792008-02-08 04:19:49 -0800337MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200338
Jan Kara366f4ae2016-10-25 13:53:27 +0200339unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE;
Joe Perches5657a812018-05-24 13:38:59 -0600340module_param(rd_size, ulong, 0444);
Nick Piggin9db55792008-02-08 04:19:49 -0800341MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200342
343static int max_part = 1;
Joe Perches5657a812018-05-24 13:38:59 -0600344module_param(max_part, int, 0444);
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200345MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
346
Nick Piggin9db55792008-02-08 04:19:49 -0800347MODULE_LICENSE("GPL");
348MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
Nick Pigginefedf512008-06-04 17:18:42 +0200349MODULE_ALIAS("rd");
Nick Piggin9db55792008-02-08 04:19:49 -0800350
351#ifndef MODULE
352/* Legacy boot options - nonmodular */
353static int __init ramdisk_size(char *str)
354{
355 rd_size = simple_strtol(str, NULL, 0);
356 return 1;
357}
Robert P. J. Day1adbee52009-06-10 12:57:08 -0700358__setup("ramdisk_size=", ramdisk_size);
Nick Piggin9db55792008-02-08 04:19:49 -0800359#endif
360
361/*
362 * The device scheme is derived from loop.c. Keep them in synch where possible
363 * (should share code eventually).
364 */
365static LIST_HEAD(brd_devices);
366static DEFINE_MUTEX(brd_devices_mutex);
367
368static struct brd_device *brd_alloc(int i)
369{
370 struct brd_device *brd;
371 struct gendisk *disk;
372
373 brd = kzalloc(sizeof(*brd), GFP_KERNEL);
374 if (!brd)
375 goto out;
376 brd->brd_number = i;
377 spin_lock_init(&brd->brd_lock);
378 INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC);
379
380 brd->brd_queue = blk_alloc_queue(GFP_KERNEL);
381 if (!brd->brd_queue)
382 goto out_free_dev;
Boaz Harroshc8fa3172015-01-07 18:09:38 +0200383
Nick Piggin9db55792008-02-08 04:19:49 -0800384 blk_queue_make_request(brd->brd_queue, brd_make_request);
Martin K. Petersen086fa5f2010-02-26 00:20:38 -0500385 blk_queue_max_hw_sectors(brd->brd_queue, 1024);
Nick Piggin9db55792008-02-08 04:19:49 -0800386
Boaz Harroshc8fa3172015-01-07 18:09:38 +0200387 /* This is so fdisk will align partitions on 4k, because of
388 * direct_access API needing 4k alignment, returning a PFN
389 * (This is only a problem on very small devices <= 4M,
390 * otherwise fdisk will align on 1M. Regardless this call
391 * is harmless)
392 */
393 blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200394 disk = brd->brd_disk = alloc_disk(max_part);
Nick Piggin9db55792008-02-08 04:19:49 -0800395 if (!disk)
396 goto out_free_queue;
397 disk->major = RAMDISK_MAJOR;
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200398 disk->first_minor = i * max_part;
Nick Piggin9db55792008-02-08 04:19:49 -0800399 disk->fops = &brd_fops;
400 disk->private_data = brd;
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200401 disk->flags = GENHD_FL_EXT_DEVT;
Nick Piggin9db55792008-02-08 04:19:49 -0800402 sprintf(disk->disk_name, "ram%d", i);
403 set_capacity(disk, rd_size * 2);
Ming Lei153fcd52018-11-02 08:50:51 +0800404 brd->brd_queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
Nick Piggin9db55792008-02-08 04:19:49 -0800405
SeongJae Park316ba572018-05-03 18:53:26 +0900406 /* Tell the block layer that this is not a rotational device */
Ming Lei153fcd52018-11-02 08:50:51 +0800407 blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
408 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, brd->brd_queue);
SeongJae Park316ba572018-05-03 18:53:26 +0900409
Nick Piggin9db55792008-02-08 04:19:49 -0800410 return brd;
411
412out_free_queue:
413 blk_cleanup_queue(brd->brd_queue);
414out_free_dev:
415 kfree(brd);
416out:
417 return NULL;
418}
419
420static void brd_free(struct brd_device *brd)
421{
422 put_disk(brd->brd_disk);
423 blk_cleanup_queue(brd->brd_queue);
424 brd_free_pages(brd);
425 kfree(brd);
426}
427
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200428static struct brd_device *brd_init_one(int i, bool *new)
Nick Piggin9db55792008-02-08 04:19:49 -0800429{
430 struct brd_device *brd;
431
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200432 *new = false;
Nick Piggin9db55792008-02-08 04:19:49 -0800433 list_for_each_entry(brd, &brd_devices, brd_list) {
434 if (brd->brd_number == i)
435 goto out;
436 }
437
438 brd = brd_alloc(i);
439 if (brd) {
Ming Lei153fcd52018-11-02 08:50:51 +0800440 brd->brd_disk->queue = brd->brd_queue;
Nick Piggin9db55792008-02-08 04:19:49 -0800441 add_disk(brd->brd_disk);
442 list_add_tail(&brd->brd_list, &brd_devices);
443 }
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200444 *new = true;
Nick Piggin9db55792008-02-08 04:19:49 -0800445out:
446 return brd;
447}
448
449static void brd_del_one(struct brd_device *brd)
450{
451 list_del(&brd->brd_list);
452 del_gendisk(brd->brd_disk);
453 brd_free(brd);
454}
455
456static struct kobject *brd_probe(dev_t dev, int *part, void *data)
457{
458 struct brd_device *brd;
459 struct kobject *kobj;
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200460 bool new;
Nick Piggin9db55792008-02-08 04:19:49 -0800461
462 mutex_lock(&brd_devices_mutex);
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200463 brd = brd_init_one(MINOR(dev) / max_part, &new);
Jan Kara3079c222018-02-26 13:01:38 +0100464 kobj = brd ? get_disk_and_module(brd->brd_disk) : NULL;
Nick Piggin9db55792008-02-08 04:19:49 -0800465 mutex_unlock(&brd_devices_mutex);
466
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200467 if (new)
468 *part = 0;
469
Nick Piggin9db55792008-02-08 04:19:49 -0800470 return kobj;
471}
472
473static int __init brd_init(void)
474{
Nick Piggin9db55792008-02-08 04:19:49 -0800475 struct brd_device *brd, *next;
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200476 int i;
Nick Piggin9db55792008-02-08 04:19:49 -0800477
478 /*
479 * brd module now has a feature to instantiate underlying device
480 * structure on-demand, provided that there is an access dev node.
Nick Piggin9db55792008-02-08 04:19:49 -0800481 *
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200482 * (1) if rd_nr is specified, create that many upfront. else
483 * it defaults to CONFIG_BLK_DEV_RAM_COUNT
484 * (2) User can further extend brd devices by create dev node themselves
485 * and have kernel automatically instantiate actual device
486 * on-demand. Example:
487 * mknod /path/devnod_name b 1 X # 1 is the rd major
488 * fdisk -l /path/devnod_name
489 * If (X / max_part) was not already created it will be created
490 * dynamically.
Nick Piggin9db55792008-02-08 04:19:49 -0800491 */
Laurent Vivierd7853d12008-04-30 00:55:06 -0700492
Nick Piggin9db55792008-02-08 04:19:49 -0800493 if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))
494 return -EIO;
495
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200496 if (unlikely(!max_part))
497 max_part = 1;
498
499 for (i = 0; i < rd_nr; i++) {
Nick Piggin9db55792008-02-08 04:19:49 -0800500 brd = brd_alloc(i);
501 if (!brd)
502 goto out_free;
503 list_add_tail(&brd->brd_list, &brd_devices);
504 }
505
506 /* point of no return */
507
Ming Lei153fcd52018-11-02 08:50:51 +0800508 list_for_each_entry(brd, &brd_devices, brd_list) {
509 /*
510 * associate with queue just before adding disk for
511 * avoiding to mess up failure path
512 */
513 brd->brd_disk->queue = brd->brd_queue;
Nick Piggin9db55792008-02-08 04:19:49 -0800514 add_disk(brd->brd_disk);
Ming Lei153fcd52018-11-02 08:50:51 +0800515 }
Nick Piggin9db55792008-02-08 04:19:49 -0800516
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200517 blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS,
Nick Piggin9db55792008-02-08 04:19:49 -0800518 THIS_MODULE, brd_probe, NULL, NULL);
519
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200520 pr_info("brd: module loaded\n");
Nick Piggin9db55792008-02-08 04:19:49 -0800521 return 0;
522
523out_free:
524 list_for_each_entry_safe(brd, next, &brd_devices, brd_list) {
525 list_del(&brd->brd_list);
526 brd_free(brd);
527 }
Akinobu Mitac82f2962008-08-20 14:09:09 -0700528 unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
Nick Piggin9db55792008-02-08 04:19:49 -0800529
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200530 pr_info("brd: module NOT loaded !!!\n");
Nick Piggin9db55792008-02-08 04:19:49 -0800531 return -ENOMEM;
532}
533
534static void __exit brd_exit(void)
535{
Nick Piggin9db55792008-02-08 04:19:49 -0800536 struct brd_device *brd, *next;
537
Nick Piggin9db55792008-02-08 04:19:49 -0800538 list_for_each_entry_safe(brd, next, &brd_devices, brd_list)
539 brd_del_one(brd);
540
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200541 blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS);
Nick Piggin9db55792008-02-08 04:19:49 -0800542 unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
Boaz Harrosh937af5e2015-01-07 18:07:56 +0200543
544 pr_info("brd: module unloaded\n");
Nick Piggin9db55792008-02-08 04:19:49 -0800545}
546
547module_init(brd_init);
548module_exit(brd_exit);
549