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Commit | Line | Data |
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9db5579b NP |
1 | /* |
2 | * Ram backed block device driver. | |
3 | * | |
4 | * Copyright (C) 2007 Nick Piggin | |
5 | * Copyright (C) 2007 Novell Inc. | |
6 | * | |
7 | * Parts derived from drivers/block/rd.c, and drivers/block/loop.c, copyright | |
8 | * of their respective owners. | |
9 | */ | |
10 | ||
11 | #include <linux/init.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/moduleparam.h> | |
14 | #include <linux/major.h> | |
15 | #include <linux/blkdev.h> | |
16 | #include <linux/bio.h> | |
17 | #include <linux/highmem.h> | |
2a48fc0a | 18 | #include <linux/mutex.h> |
9db5579b | 19 | #include <linux/radix-tree.h> |
ff01bb48 | 20 | #include <linux/fs.h> |
5a0e3ad6 | 21 | #include <linux/slab.h> |
34c0fd54 DW |
22 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
23 | #include <linux/pfn_t.h> | |
1647b9b9 | 24 | #include <linux/dax.h> |
34c0fd54 | 25 | #endif |
9db5579b | 26 | |
7c0f6ba6 | 27 | #include <linux/uaccess.h> |
9db5579b NP |
28 | |
29 | #define SECTOR_SHIFT 9 | |
30 | #define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) | |
31 | #define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT) | |
32 | ||
33 | /* | |
34 | * Each block ramdisk device has a radix_tree brd_pages of pages that stores | |
35 | * the pages containing the block device's contents. A brd page's ->index is | |
36 | * its offset in PAGE_SIZE units. This is similar to, but in no way connected | |
37 | * with, the kernel's pagecache or buffer cache (which sit above our block | |
38 | * device). | |
39 | */ | |
40 | struct brd_device { | |
41 | int brd_number; | |
9db5579b NP |
42 | |
43 | struct request_queue *brd_queue; | |
44 | struct gendisk *brd_disk; | |
1647b9b9 DW |
45 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
46 | struct dax_device *dax_dev; | |
47 | #endif | |
9db5579b NP |
48 | struct list_head brd_list; |
49 | ||
50 | /* | |
51 | * Backing store of pages and lock to protect it. This is the contents | |
52 | * of the block device. | |
53 | */ | |
54 | spinlock_t brd_lock; | |
55 | struct radix_tree_root brd_pages; | |
56 | }; | |
57 | ||
58 | /* | |
59 | * Look up and return a brd's page for a given sector. | |
60 | */ | |
2a48fc0a | 61 | static DEFINE_MUTEX(brd_mutex); |
9db5579b NP |
62 | static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) |
63 | { | |
64 | pgoff_t idx; | |
65 | struct page *page; | |
66 | ||
67 | /* | |
68 | * The page lifetime is protected by the fact that we have opened the | |
69 | * device node -- brd pages will never be deleted under us, so we | |
70 | * don't need any further locking or refcounting. | |
71 | * | |
72 | * This is strictly true for the radix-tree nodes as well (ie. we | |
73 | * don't actually need the rcu_read_lock()), however that is not a | |
74 | * documented feature of the radix-tree API so it is better to be | |
75 | * safe here (we don't have total exclusion from radix tree updates | |
76 | * here, only deletes). | |
77 | */ | |
78 | rcu_read_lock(); | |
79 | idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ | |
80 | page = radix_tree_lookup(&brd->brd_pages, idx); | |
81 | rcu_read_unlock(); | |
82 | ||
83 | BUG_ON(page && page->index != idx); | |
84 | ||
85 | return page; | |
86 | } | |
87 | ||
88 | /* | |
89 | * Look up and return a brd's page for a given sector. | |
90 | * If one does not exist, allocate an empty page, and insert that. Then | |
91 | * return it. | |
92 | */ | |
93 | static struct page *brd_insert_page(struct brd_device *brd, sector_t sector) | |
94 | { | |
95 | pgoff_t idx; | |
96 | struct page *page; | |
75acb9cd | 97 | gfp_t gfp_flags; |
9db5579b NP |
98 | |
99 | page = brd_lookup_page(brd, sector); | |
100 | if (page) | |
101 | return page; | |
102 | ||
103 | /* | |
104 | * Must use NOIO because we don't want to recurse back into the | |
105 | * block or filesystem layers from page reclaim. | |
75acb9cd | 106 | * |
a7a97fc9 MW |
107 | * Cannot support DAX and highmem, because our ->direct_access |
108 | * routine for DAX must return memory that is always addressable. | |
109 | * If DAX was reworked to use pfns and kmap throughout, this | |
75acb9cd | 110 | * restriction might be able to be lifted. |
9db5579b | 111 | */ |
75acb9cd | 112 | gfp_flags = GFP_NOIO | __GFP_ZERO; |
a7a97fc9 | 113 | #ifndef CONFIG_BLK_DEV_RAM_DAX |
75acb9cd NP |
114 | gfp_flags |= __GFP_HIGHMEM; |
115 | #endif | |
26defe34 | 116 | page = alloc_page(gfp_flags); |
9db5579b NP |
117 | if (!page) |
118 | return NULL; | |
119 | ||
120 | if (radix_tree_preload(GFP_NOIO)) { | |
121 | __free_page(page); | |
122 | return NULL; | |
123 | } | |
124 | ||
125 | spin_lock(&brd->brd_lock); | |
126 | idx = sector >> PAGE_SECTORS_SHIFT; | |
dfd20b2b | 127 | page->index = idx; |
9db5579b NP |
128 | if (radix_tree_insert(&brd->brd_pages, idx, page)) { |
129 | __free_page(page); | |
130 | page = radix_tree_lookup(&brd->brd_pages, idx); | |
131 | BUG_ON(!page); | |
132 | BUG_ON(page->index != idx); | |
dfd20b2b | 133 | } |
9db5579b NP |
134 | spin_unlock(&brd->brd_lock); |
135 | ||
136 | radix_tree_preload_end(); | |
137 | ||
138 | return page; | |
139 | } | |
140 | ||
141 | /* | |
142 | * Free all backing store pages and radix tree. This must only be called when | |
143 | * there are no other users of the device. | |
144 | */ | |
145 | #define FREE_BATCH 16 | |
146 | static void brd_free_pages(struct brd_device *brd) | |
147 | { | |
148 | unsigned long pos = 0; | |
149 | struct page *pages[FREE_BATCH]; | |
150 | int nr_pages; | |
151 | ||
152 | do { | |
153 | int i; | |
154 | ||
155 | nr_pages = radix_tree_gang_lookup(&brd->brd_pages, | |
156 | (void **)pages, pos, FREE_BATCH); | |
157 | ||
158 | for (i = 0; i < nr_pages; i++) { | |
159 | void *ret; | |
160 | ||
161 | BUG_ON(pages[i]->index < pos); | |
162 | pos = pages[i]->index; | |
163 | ret = radix_tree_delete(&brd->brd_pages, pos); | |
164 | BUG_ON(!ret || ret != pages[i]); | |
165 | __free_page(pages[i]); | |
166 | } | |
167 | ||
168 | pos++; | |
169 | ||
170 | /* | |
171 | * This assumes radix_tree_gang_lookup always returns as | |
172 | * many pages as possible. If the radix-tree code changes, | |
173 | * so will this have to. | |
174 | */ | |
175 | } while (nr_pages == FREE_BATCH); | |
176 | } | |
177 | ||
178 | /* | |
179 | * copy_to_brd_setup must be called before copy_to_brd. It may sleep. | |
180 | */ | |
181 | static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) | |
182 | { | |
183 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; | |
184 | size_t copy; | |
185 | ||
186 | copy = min_t(size_t, n, PAGE_SIZE - offset); | |
187 | if (!brd_insert_page(brd, sector)) | |
96f8d8e0 | 188 | return -ENOSPC; |
9db5579b NP |
189 | if (copy < n) { |
190 | sector += copy >> SECTOR_SHIFT; | |
191 | if (!brd_insert_page(brd, sector)) | |
96f8d8e0 | 192 | return -ENOSPC; |
9db5579b NP |
193 | } |
194 | return 0; | |
195 | } | |
196 | ||
197 | /* | |
198 | * Copy n bytes from src to the brd starting at sector. Does not sleep. | |
199 | */ | |
200 | static void copy_to_brd(struct brd_device *brd, const void *src, | |
201 | sector_t sector, size_t n) | |
202 | { | |
203 | struct page *page; | |
204 | void *dst; | |
205 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; | |
206 | size_t copy; | |
207 | ||
208 | copy = min_t(size_t, n, PAGE_SIZE - offset); | |
209 | page = brd_lookup_page(brd, sector); | |
210 | BUG_ON(!page); | |
211 | ||
cfd8005c | 212 | dst = kmap_atomic(page); |
9db5579b | 213 | memcpy(dst + offset, src, copy); |
cfd8005c | 214 | kunmap_atomic(dst); |
9db5579b NP |
215 | |
216 | if (copy < n) { | |
217 | src += copy; | |
218 | sector += copy >> SECTOR_SHIFT; | |
219 | copy = n - copy; | |
220 | page = brd_lookup_page(brd, sector); | |
221 | BUG_ON(!page); | |
222 | ||
cfd8005c | 223 | dst = kmap_atomic(page); |
9db5579b | 224 | memcpy(dst, src, copy); |
cfd8005c | 225 | kunmap_atomic(dst); |
9db5579b NP |
226 | } |
227 | } | |
228 | ||
229 | /* | |
230 | * Copy n bytes to dst from the brd starting at sector. Does not sleep. | |
231 | */ | |
232 | static void copy_from_brd(void *dst, struct brd_device *brd, | |
233 | sector_t sector, size_t n) | |
234 | { | |
235 | struct page *page; | |
236 | void *src; | |
237 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; | |
238 | size_t copy; | |
239 | ||
240 | copy = min_t(size_t, n, PAGE_SIZE - offset); | |
241 | page = brd_lookup_page(brd, sector); | |
242 | if (page) { | |
cfd8005c | 243 | src = kmap_atomic(page); |
9db5579b | 244 | memcpy(dst, src + offset, copy); |
cfd8005c | 245 | kunmap_atomic(src); |
9db5579b NP |
246 | } else |
247 | memset(dst, 0, copy); | |
248 | ||
249 | if (copy < n) { | |
250 | dst += copy; | |
251 | sector += copy >> SECTOR_SHIFT; | |
252 | copy = n - copy; | |
253 | page = brd_lookup_page(brd, sector); | |
254 | if (page) { | |
cfd8005c | 255 | src = kmap_atomic(page); |
9db5579b | 256 | memcpy(dst, src, copy); |
cfd8005c | 257 | kunmap_atomic(src); |
9db5579b NP |
258 | } else |
259 | memset(dst, 0, copy); | |
260 | } | |
261 | } | |
262 | ||
263 | /* | |
264 | * Process a single bvec of a bio. | |
265 | */ | |
266 | static int brd_do_bvec(struct brd_device *brd, struct page *page, | |
c11f0c0b | 267 | unsigned int len, unsigned int off, bool is_write, |
9db5579b NP |
268 | sector_t sector) |
269 | { | |
270 | void *mem; | |
271 | int err = 0; | |
272 | ||
c11f0c0b | 273 | if (is_write) { |
9db5579b NP |
274 | err = copy_to_brd_setup(brd, sector, len); |
275 | if (err) | |
276 | goto out; | |
277 | } | |
278 | ||
cfd8005c | 279 | mem = kmap_atomic(page); |
c11f0c0b | 280 | if (!is_write) { |
9db5579b NP |
281 | copy_from_brd(mem + off, brd, sector, len); |
282 | flush_dcache_page(page); | |
c2572f2b NP |
283 | } else { |
284 | flush_dcache_page(page); | |
9db5579b | 285 | copy_to_brd(brd, mem + off, sector, len); |
c2572f2b | 286 | } |
cfd8005c | 287 | kunmap_atomic(mem); |
9db5579b NP |
288 | |
289 | out: | |
290 | return err; | |
291 | } | |
292 | ||
dece1635 | 293 | static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio) |
9db5579b NP |
294 | { |
295 | struct block_device *bdev = bio->bi_bdev; | |
296 | struct brd_device *brd = bdev->bd_disk->private_data; | |
7988613b | 297 | struct bio_vec bvec; |
9db5579b | 298 | sector_t sector; |
7988613b | 299 | struct bvec_iter iter; |
9db5579b | 300 | |
4f024f37 | 301 | sector = bio->bi_iter.bi_sector; |
f73a1c7d | 302 | if (bio_end_sector(bio) > get_capacity(bdev->bd_disk)) |
4246a0b6 | 303 | goto io_error; |
9db5579b | 304 | |
7988613b KO |
305 | bio_for_each_segment(bvec, bio, iter) { |
306 | unsigned int len = bvec.bv_len; | |
4246a0b6 CH |
307 | int err; |
308 | ||
c11f0c0b JA |
309 | err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset, |
310 | op_is_write(bio_op(bio)), sector); | |
9db5579b | 311 | if (err) |
4246a0b6 | 312 | goto io_error; |
9db5579b NP |
313 | sector += len >> SECTOR_SHIFT; |
314 | } | |
315 | ||
4246a0b6 | 316 | bio_endio(bio); |
dece1635 | 317 | return BLK_QC_T_NONE; |
4246a0b6 CH |
318 | io_error: |
319 | bio_io_error(bio); | |
dece1635 | 320 | return BLK_QC_T_NONE; |
9db5579b NP |
321 | } |
322 | ||
a72132c3 | 323 | static int brd_rw_page(struct block_device *bdev, sector_t sector, |
c11f0c0b | 324 | struct page *page, bool is_write) |
a72132c3 MW |
325 | { |
326 | struct brd_device *brd = bdev->bd_disk->private_data; | |
c11f0c0b JA |
327 | int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector); |
328 | page_endio(page, is_write, err); | |
a72132c3 MW |
329 | return err; |
330 | } | |
331 | ||
a7a97fc9 | 332 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
1647b9b9 DW |
333 | static long __brd_direct_access(struct brd_device *brd, pgoff_t pgoff, |
334 | long nr_pages, void **kaddr, pfn_t *pfn) | |
75acb9cd | 335 | { |
75acb9cd NP |
336 | struct page *page; |
337 | ||
338 | if (!brd) | |
339 | return -ENODEV; | |
1647b9b9 | 340 | page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512); |
75acb9cd | 341 | if (!page) |
96f8d8e0 | 342 | return -ENOSPC; |
7a9eb206 | 343 | *kaddr = page_address(page); |
34c0fd54 | 344 | *pfn = page_to_pfn_t(page); |
75acb9cd | 345 | |
1647b9b9 | 346 | return 1; |
75acb9cd | 347 | } |
1647b9b9 | 348 | |
1647b9b9 DW |
349 | static long brd_dax_direct_access(struct dax_device *dax_dev, |
350 | pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn) | |
351 | { | |
352 | struct brd_device *brd = dax_get_private(dax_dev); | |
353 | ||
354 | return __brd_direct_access(brd, pgoff, nr_pages, kaddr, pfn); | |
75acb9cd | 355 | } |
1647b9b9 DW |
356 | |
357 | static const struct dax_operations brd_dax_ops = { | |
358 | .direct_access = brd_dax_direct_access, | |
359 | }; | |
75acb9cd NP |
360 | #endif |
361 | ||
83d5cde4 | 362 | static const struct block_device_operations brd_fops = { |
75acb9cd | 363 | .owner = THIS_MODULE, |
a72132c3 | 364 | .rw_page = brd_rw_page, |
9db5579b NP |
365 | }; |
366 | ||
367 | /* | |
368 | * And now the modules code and kernel interface. | |
369 | */ | |
937af5ec | 370 | static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; |
8892cbaf | 371 | module_param(rd_nr, int, S_IRUGO); |
9db5579b | 372 | MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); |
937af5ec | 373 | |
366f4aea JK |
374 | unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; |
375 | module_param(rd_size, ulong, S_IRUGO); | |
9db5579b | 376 | MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); |
937af5ec BH |
377 | |
378 | static int max_part = 1; | |
8892cbaf | 379 | module_param(max_part, int, S_IRUGO); |
937af5ec BH |
380 | MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); |
381 | ||
9db5579b NP |
382 | MODULE_LICENSE("GPL"); |
383 | MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); | |
efedf51c | 384 | MODULE_ALIAS("rd"); |
9db5579b NP |
385 | |
386 | #ifndef MODULE | |
387 | /* Legacy boot options - nonmodular */ | |
388 | static int __init ramdisk_size(char *str) | |
389 | { | |
390 | rd_size = simple_strtol(str, NULL, 0); | |
391 | return 1; | |
392 | } | |
1adbee50 | 393 | __setup("ramdisk_size=", ramdisk_size); |
9db5579b NP |
394 | #endif |
395 | ||
396 | /* | |
397 | * The device scheme is derived from loop.c. Keep them in synch where possible | |
398 | * (should share code eventually). | |
399 | */ | |
400 | static LIST_HEAD(brd_devices); | |
401 | static DEFINE_MUTEX(brd_devices_mutex); | |
402 | ||
403 | static struct brd_device *brd_alloc(int i) | |
404 | { | |
405 | struct brd_device *brd; | |
406 | struct gendisk *disk; | |
407 | ||
408 | brd = kzalloc(sizeof(*brd), GFP_KERNEL); | |
409 | if (!brd) | |
410 | goto out; | |
411 | brd->brd_number = i; | |
412 | spin_lock_init(&brd->brd_lock); | |
413 | INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); | |
414 | ||
415 | brd->brd_queue = blk_alloc_queue(GFP_KERNEL); | |
416 | if (!brd->brd_queue) | |
417 | goto out_free_dev; | |
c8fa3173 | 418 | |
9db5579b | 419 | blk_queue_make_request(brd->brd_queue, brd_make_request); |
086fa5ff | 420 | blk_queue_max_hw_sectors(brd->brd_queue, 1024); |
9db5579b NP |
421 | blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); |
422 | ||
c8fa3173 BH |
423 | /* This is so fdisk will align partitions on 4k, because of |
424 | * direct_access API needing 4k alignment, returning a PFN | |
425 | * (This is only a problem on very small devices <= 4M, | |
426 | * otherwise fdisk will align on 1M. Regardless this call | |
427 | * is harmless) | |
428 | */ | |
429 | blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); | |
937af5ec | 430 | disk = brd->brd_disk = alloc_disk(max_part); |
9db5579b NP |
431 | if (!disk) |
432 | goto out_free_queue; | |
433 | disk->major = RAMDISK_MAJOR; | |
937af5ec | 434 | disk->first_minor = i * max_part; |
9db5579b NP |
435 | disk->fops = &brd_fops; |
436 | disk->private_data = brd; | |
437 | disk->queue = brd->brd_queue; | |
937af5ec | 438 | disk->flags = GENHD_FL_EXT_DEVT; |
9db5579b NP |
439 | sprintf(disk->disk_name, "ram%d", i); |
440 | set_capacity(disk, rd_size * 2); | |
441 | ||
1647b9b9 DW |
442 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
443 | queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue); | |
1ef97fe4 GS |
444 | brd->dax_dev = alloc_dax(brd, disk->disk_name, &brd_dax_ops); |
445 | if (!brd->dax_dev) | |
1647b9b9 DW |
446 | goto out_free_inode; |
447 | #endif | |
448 | ||
449 | ||
9db5579b NP |
450 | return brd; |
451 | ||
1647b9b9 DW |
452 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
453 | out_free_inode: | |
1ef97fe4 GS |
454 | kill_dax(brd->dax_dev); |
455 | put_dax(brd->dax_dev); | |
1647b9b9 | 456 | #endif |
9db5579b NP |
457 | out_free_queue: |
458 | blk_cleanup_queue(brd->brd_queue); | |
459 | out_free_dev: | |
460 | kfree(brd); | |
461 | out: | |
462 | return NULL; | |
463 | } | |
464 | ||
465 | static void brd_free(struct brd_device *brd) | |
466 | { | |
467 | put_disk(brd->brd_disk); | |
468 | blk_cleanup_queue(brd->brd_queue); | |
469 | brd_free_pages(brd); | |
470 | kfree(brd); | |
471 | } | |
472 | ||
937af5ec | 473 | static struct brd_device *brd_init_one(int i, bool *new) |
9db5579b NP |
474 | { |
475 | struct brd_device *brd; | |
476 | ||
937af5ec | 477 | *new = false; |
9db5579b NP |
478 | list_for_each_entry(brd, &brd_devices, brd_list) { |
479 | if (brd->brd_number == i) | |
480 | goto out; | |
481 | } | |
482 | ||
483 | brd = brd_alloc(i); | |
484 | if (brd) { | |
485 | add_disk(brd->brd_disk); | |
486 | list_add_tail(&brd->brd_list, &brd_devices); | |
487 | } | |
937af5ec | 488 | *new = true; |
9db5579b NP |
489 | out: |
490 | return brd; | |
491 | } | |
492 | ||
493 | static void brd_del_one(struct brd_device *brd) | |
494 | { | |
495 | list_del(&brd->brd_list); | |
1647b9b9 DW |
496 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
497 | kill_dax(brd->dax_dev); | |
498 | put_dax(brd->dax_dev); | |
499 | #endif | |
9db5579b NP |
500 | del_gendisk(brd->brd_disk); |
501 | brd_free(brd); | |
502 | } | |
503 | ||
504 | static struct kobject *brd_probe(dev_t dev, int *part, void *data) | |
505 | { | |
506 | struct brd_device *brd; | |
507 | struct kobject *kobj; | |
937af5ec | 508 | bool new; |
9db5579b NP |
509 | |
510 | mutex_lock(&brd_devices_mutex); | |
937af5ec | 511 | brd = brd_init_one(MINOR(dev) / max_part, &new); |
a207f593 | 512 | kobj = brd ? get_disk(brd->brd_disk) : NULL; |
9db5579b NP |
513 | mutex_unlock(&brd_devices_mutex); |
514 | ||
937af5ec BH |
515 | if (new) |
516 | *part = 0; | |
517 | ||
9db5579b NP |
518 | return kobj; |
519 | } | |
520 | ||
521 | static int __init brd_init(void) | |
522 | { | |
9db5579b | 523 | struct brd_device *brd, *next; |
937af5ec | 524 | int i; |
9db5579b NP |
525 | |
526 | /* | |
527 | * brd module now has a feature to instantiate underlying device | |
528 | * structure on-demand, provided that there is an access dev node. | |
9db5579b | 529 | * |
937af5ec BH |
530 | * (1) if rd_nr is specified, create that many upfront. else |
531 | * it defaults to CONFIG_BLK_DEV_RAM_COUNT | |
532 | * (2) User can further extend brd devices by create dev node themselves | |
533 | * and have kernel automatically instantiate actual device | |
534 | * on-demand. Example: | |
535 | * mknod /path/devnod_name b 1 X # 1 is the rd major | |
536 | * fdisk -l /path/devnod_name | |
537 | * If (X / max_part) was not already created it will be created | |
538 | * dynamically. | |
9db5579b | 539 | */ |
d7853d1f | 540 | |
9db5579b NP |
541 | if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) |
542 | return -EIO; | |
543 | ||
937af5ec BH |
544 | if (unlikely(!max_part)) |
545 | max_part = 1; | |
546 | ||
547 | for (i = 0; i < rd_nr; i++) { | |
9db5579b NP |
548 | brd = brd_alloc(i); |
549 | if (!brd) | |
550 | goto out_free; | |
551 | list_add_tail(&brd->brd_list, &brd_devices); | |
552 | } | |
553 | ||
554 | /* point of no return */ | |
555 | ||
556 | list_for_each_entry(brd, &brd_devices, brd_list) | |
557 | add_disk(brd->brd_disk); | |
558 | ||
937af5ec | 559 | blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS, |
9db5579b NP |
560 | THIS_MODULE, brd_probe, NULL, NULL); |
561 | ||
937af5ec | 562 | pr_info("brd: module loaded\n"); |
9db5579b NP |
563 | return 0; |
564 | ||
565 | out_free: | |
566 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { | |
567 | list_del(&brd->brd_list); | |
568 | brd_free(brd); | |
569 | } | |
c82f2966 | 570 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
9db5579b | 571 | |
937af5ec | 572 | pr_info("brd: module NOT loaded !!!\n"); |
9db5579b NP |
573 | return -ENOMEM; |
574 | } | |
575 | ||
576 | static void __exit brd_exit(void) | |
577 | { | |
9db5579b NP |
578 | struct brd_device *brd, *next; |
579 | ||
9db5579b NP |
580 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) |
581 | brd_del_one(brd); | |
582 | ||
937af5ec | 583 | blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS); |
9db5579b | 584 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
937af5ec BH |
585 | |
586 | pr_info("brd: module unloaded\n"); | |
9db5579b NP |
587 | } |
588 | ||
589 | module_init(brd_init); | |
590 | module_exit(brd_exit); | |
591 |