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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 | ||
b7c33571 NP |
141 | static void brd_free_page(struct brd_device *brd, sector_t sector) |
142 | { | |
143 | struct page *page; | |
144 | pgoff_t idx; | |
145 | ||
146 | spin_lock(&brd->brd_lock); | |
147 | idx = sector >> PAGE_SECTORS_SHIFT; | |
148 | page = radix_tree_delete(&brd->brd_pages, idx); | |
149 | spin_unlock(&brd->brd_lock); | |
150 | if (page) | |
151 | __free_page(page); | |
152 | } | |
153 | ||
154 | static void brd_zero_page(struct brd_device *brd, sector_t sector) | |
155 | { | |
156 | struct page *page; | |
157 | ||
158 | page = brd_lookup_page(brd, sector); | |
159 | if (page) | |
160 | clear_highpage(page); | |
161 | } | |
162 | ||
9db5579b NP |
163 | /* |
164 | * Free all backing store pages and radix tree. This must only be called when | |
165 | * there are no other users of the device. | |
166 | */ | |
167 | #define FREE_BATCH 16 | |
168 | static void brd_free_pages(struct brd_device *brd) | |
169 | { | |
170 | unsigned long pos = 0; | |
171 | struct page *pages[FREE_BATCH]; | |
172 | int nr_pages; | |
173 | ||
174 | do { | |
175 | int i; | |
176 | ||
177 | nr_pages = radix_tree_gang_lookup(&brd->brd_pages, | |
178 | (void **)pages, pos, FREE_BATCH); | |
179 | ||
180 | for (i = 0; i < nr_pages; i++) { | |
181 | void *ret; | |
182 | ||
183 | BUG_ON(pages[i]->index < pos); | |
184 | pos = pages[i]->index; | |
185 | ret = radix_tree_delete(&brd->brd_pages, pos); | |
186 | BUG_ON(!ret || ret != pages[i]); | |
187 | __free_page(pages[i]); | |
188 | } | |
189 | ||
190 | pos++; | |
191 | ||
192 | /* | |
193 | * This assumes radix_tree_gang_lookup always returns as | |
194 | * many pages as possible. If the radix-tree code changes, | |
195 | * so will this have to. | |
196 | */ | |
197 | } while (nr_pages == FREE_BATCH); | |
198 | } | |
199 | ||
200 | /* | |
201 | * copy_to_brd_setup must be called before copy_to_brd. It may sleep. | |
202 | */ | |
203 | static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) | |
204 | { | |
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 | if (!brd_insert_page(brd, sector)) | |
96f8d8e0 | 210 | return -ENOSPC; |
9db5579b NP |
211 | if (copy < n) { |
212 | sector += copy >> SECTOR_SHIFT; | |
213 | if (!brd_insert_page(brd, sector)) | |
96f8d8e0 | 214 | return -ENOSPC; |
9db5579b NP |
215 | } |
216 | return 0; | |
217 | } | |
218 | ||
b7c33571 NP |
219 | static void discard_from_brd(struct brd_device *brd, |
220 | sector_t sector, size_t n) | |
221 | { | |
222 | while (n >= PAGE_SIZE) { | |
223 | /* | |
224 | * Don't want to actually discard pages here because | |
225 | * re-allocating the pages can result in writeback | |
226 | * deadlocks under heavy load. | |
227 | */ | |
228 | if (0) | |
229 | brd_free_page(brd, sector); | |
230 | else | |
231 | brd_zero_page(brd, sector); | |
232 | sector += PAGE_SIZE >> SECTOR_SHIFT; | |
233 | n -= PAGE_SIZE; | |
234 | } | |
235 | } | |
236 | ||
9db5579b NP |
237 | /* |
238 | * Copy n bytes from src to the brd starting at sector. Does not sleep. | |
239 | */ | |
240 | static void copy_to_brd(struct brd_device *brd, const void *src, | |
241 | sector_t sector, size_t n) | |
242 | { | |
243 | struct page *page; | |
244 | void *dst; | |
245 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; | |
246 | size_t copy; | |
247 | ||
248 | copy = min_t(size_t, n, PAGE_SIZE - offset); | |
249 | page = brd_lookup_page(brd, sector); | |
250 | BUG_ON(!page); | |
251 | ||
cfd8005c | 252 | dst = kmap_atomic(page); |
9db5579b | 253 | memcpy(dst + offset, src, copy); |
cfd8005c | 254 | kunmap_atomic(dst); |
9db5579b NP |
255 | |
256 | if (copy < n) { | |
257 | src += copy; | |
258 | sector += copy >> SECTOR_SHIFT; | |
259 | copy = n - copy; | |
260 | page = brd_lookup_page(brd, sector); | |
261 | BUG_ON(!page); | |
262 | ||
cfd8005c | 263 | dst = kmap_atomic(page); |
9db5579b | 264 | memcpy(dst, src, copy); |
cfd8005c | 265 | kunmap_atomic(dst); |
9db5579b NP |
266 | } |
267 | } | |
268 | ||
269 | /* | |
270 | * Copy n bytes to dst from the brd starting at sector. Does not sleep. | |
271 | */ | |
272 | static void copy_from_brd(void *dst, struct brd_device *brd, | |
273 | sector_t sector, size_t n) | |
274 | { | |
275 | struct page *page; | |
276 | void *src; | |
277 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; | |
278 | size_t copy; | |
279 | ||
280 | copy = min_t(size_t, n, PAGE_SIZE - offset); | |
281 | page = brd_lookup_page(brd, sector); | |
282 | if (page) { | |
cfd8005c | 283 | src = kmap_atomic(page); |
9db5579b | 284 | memcpy(dst, src + offset, copy); |
cfd8005c | 285 | kunmap_atomic(src); |
9db5579b NP |
286 | } else |
287 | memset(dst, 0, copy); | |
288 | ||
289 | if (copy < n) { | |
290 | dst += copy; | |
291 | sector += copy >> SECTOR_SHIFT; | |
292 | copy = n - copy; | |
293 | page = brd_lookup_page(brd, sector); | |
294 | if (page) { | |
cfd8005c | 295 | src = kmap_atomic(page); |
9db5579b | 296 | memcpy(dst, src, copy); |
cfd8005c | 297 | kunmap_atomic(src); |
9db5579b NP |
298 | } else |
299 | memset(dst, 0, copy); | |
300 | } | |
301 | } | |
302 | ||
303 | /* | |
304 | * Process a single bvec of a bio. | |
305 | */ | |
306 | static int brd_do_bvec(struct brd_device *brd, struct page *page, | |
c11f0c0b | 307 | unsigned int len, unsigned int off, bool is_write, |
9db5579b NP |
308 | sector_t sector) |
309 | { | |
310 | void *mem; | |
311 | int err = 0; | |
312 | ||
c11f0c0b | 313 | if (is_write) { |
9db5579b NP |
314 | err = copy_to_brd_setup(brd, sector, len); |
315 | if (err) | |
316 | goto out; | |
317 | } | |
318 | ||
cfd8005c | 319 | mem = kmap_atomic(page); |
c11f0c0b | 320 | if (!is_write) { |
9db5579b NP |
321 | copy_from_brd(mem + off, brd, sector, len); |
322 | flush_dcache_page(page); | |
c2572f2b NP |
323 | } else { |
324 | flush_dcache_page(page); | |
9db5579b | 325 | copy_to_brd(brd, mem + off, sector, len); |
c2572f2b | 326 | } |
cfd8005c | 327 | kunmap_atomic(mem); |
9db5579b NP |
328 | |
329 | out: | |
330 | return err; | |
331 | } | |
332 | ||
dece1635 | 333 | static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio) |
9db5579b NP |
334 | { |
335 | struct block_device *bdev = bio->bi_bdev; | |
336 | struct brd_device *brd = bdev->bd_disk->private_data; | |
7988613b | 337 | struct bio_vec bvec; |
9db5579b | 338 | sector_t sector; |
7988613b | 339 | struct bvec_iter iter; |
9db5579b | 340 | |
4f024f37 | 341 | sector = bio->bi_iter.bi_sector; |
f73a1c7d | 342 | if (bio_end_sector(bio) > get_capacity(bdev->bd_disk)) |
4246a0b6 | 343 | goto io_error; |
9db5579b | 344 | |
95fe6c1a | 345 | if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { |
2dbe5495 | 346 | if (sector & ((PAGE_SIZE >> SECTOR_SHIFT) - 1) || |
5e4298be | 347 | bio->bi_iter.bi_size & ~PAGE_MASK) |
2dbe5495 | 348 | goto io_error; |
4f024f37 | 349 | discard_from_brd(brd, sector, bio->bi_iter.bi_size); |
b7c33571 NP |
350 | goto out; |
351 | } | |
352 | ||
7988613b KO |
353 | bio_for_each_segment(bvec, bio, iter) { |
354 | unsigned int len = bvec.bv_len; | |
4246a0b6 CH |
355 | int err; |
356 | ||
c11f0c0b JA |
357 | err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset, |
358 | op_is_write(bio_op(bio)), sector); | |
9db5579b | 359 | if (err) |
4246a0b6 | 360 | goto io_error; |
9db5579b NP |
361 | sector += len >> SECTOR_SHIFT; |
362 | } | |
363 | ||
364 | out: | |
4246a0b6 | 365 | bio_endio(bio); |
dece1635 | 366 | return BLK_QC_T_NONE; |
4246a0b6 CH |
367 | io_error: |
368 | bio_io_error(bio); | |
dece1635 | 369 | return BLK_QC_T_NONE; |
9db5579b NP |
370 | } |
371 | ||
a72132c3 | 372 | static int brd_rw_page(struct block_device *bdev, sector_t sector, |
c11f0c0b | 373 | struct page *page, bool is_write) |
a72132c3 MW |
374 | { |
375 | struct brd_device *brd = bdev->bd_disk->private_data; | |
c11f0c0b JA |
376 | int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector); |
377 | page_endio(page, is_write, err); | |
a72132c3 MW |
378 | return err; |
379 | } | |
380 | ||
a7a97fc9 | 381 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
1647b9b9 DW |
382 | static long __brd_direct_access(struct brd_device *brd, pgoff_t pgoff, |
383 | long nr_pages, void **kaddr, pfn_t *pfn) | |
75acb9cd | 384 | { |
75acb9cd NP |
385 | struct page *page; |
386 | ||
387 | if (!brd) | |
388 | return -ENODEV; | |
1647b9b9 | 389 | page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512); |
75acb9cd | 390 | if (!page) |
96f8d8e0 | 391 | return -ENOSPC; |
7a9eb206 | 392 | *kaddr = page_address(page); |
34c0fd54 | 393 | *pfn = page_to_pfn_t(page); |
75acb9cd | 394 | |
1647b9b9 DW |
395 | return 1; |
396 | } | |
397 | ||
1647b9b9 DW |
398 | static long brd_dax_direct_access(struct dax_device *dax_dev, |
399 | pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn) | |
400 | { | |
401 | struct brd_device *brd = dax_get_private(dax_dev); | |
402 | ||
403 | return __brd_direct_access(brd, pgoff, nr_pages, kaddr, pfn); | |
75acb9cd | 404 | } |
1647b9b9 DW |
405 | |
406 | static const struct dax_operations brd_dax_ops = { | |
407 | .direct_access = brd_dax_direct_access, | |
408 | }; | |
75acb9cd NP |
409 | #endif |
410 | ||
83d5cde4 | 411 | static const struct block_device_operations brd_fops = { |
75acb9cd | 412 | .owner = THIS_MODULE, |
a72132c3 | 413 | .rw_page = brd_rw_page, |
9db5579b NP |
414 | }; |
415 | ||
416 | /* | |
417 | * And now the modules code and kernel interface. | |
418 | */ | |
937af5ec | 419 | static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; |
8892cbaf | 420 | module_param(rd_nr, int, S_IRUGO); |
9db5579b | 421 | MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); |
937af5ec | 422 | |
366f4aea JK |
423 | unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; |
424 | module_param(rd_size, ulong, S_IRUGO); | |
9db5579b | 425 | MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); |
937af5ec BH |
426 | |
427 | static int max_part = 1; | |
8892cbaf | 428 | module_param(max_part, int, S_IRUGO); |
937af5ec BH |
429 | MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); |
430 | ||
9db5579b NP |
431 | MODULE_LICENSE("GPL"); |
432 | MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); | |
efedf51c | 433 | MODULE_ALIAS("rd"); |
9db5579b NP |
434 | |
435 | #ifndef MODULE | |
436 | /* Legacy boot options - nonmodular */ | |
437 | static int __init ramdisk_size(char *str) | |
438 | { | |
439 | rd_size = simple_strtol(str, NULL, 0); | |
440 | return 1; | |
441 | } | |
1adbee50 | 442 | __setup("ramdisk_size=", ramdisk_size); |
9db5579b NP |
443 | #endif |
444 | ||
445 | /* | |
446 | * The device scheme is derived from loop.c. Keep them in synch where possible | |
447 | * (should share code eventually). | |
448 | */ | |
449 | static LIST_HEAD(brd_devices); | |
450 | static DEFINE_MUTEX(brd_devices_mutex); | |
451 | ||
452 | static struct brd_device *brd_alloc(int i) | |
453 | { | |
454 | struct brd_device *brd; | |
455 | struct gendisk *disk; | |
1647b9b9 DW |
456 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
457 | struct dax_device *dax_dev; | |
458 | #endif | |
9db5579b NP |
459 | brd = kzalloc(sizeof(*brd), GFP_KERNEL); |
460 | if (!brd) | |
461 | goto out; | |
462 | brd->brd_number = i; | |
463 | spin_lock_init(&brd->brd_lock); | |
464 | INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); | |
465 | ||
466 | brd->brd_queue = blk_alloc_queue(GFP_KERNEL); | |
467 | if (!brd->brd_queue) | |
468 | goto out_free_dev; | |
c8fa3173 | 469 | |
9db5579b | 470 | blk_queue_make_request(brd->brd_queue, brd_make_request); |
086fa5ff | 471 | blk_queue_max_hw_sectors(brd->brd_queue, 1024); |
9db5579b NP |
472 | blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); |
473 | ||
c8fa3173 BH |
474 | /* This is so fdisk will align partitions on 4k, because of |
475 | * direct_access API needing 4k alignment, returning a PFN | |
476 | * (This is only a problem on very small devices <= 4M, | |
477 | * otherwise fdisk will align on 1M. Regardless this call | |
478 | * is harmless) | |
479 | */ | |
480 | blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); | |
481 | ||
b7c33571 | 482 | brd->brd_queue->limits.discard_granularity = PAGE_SIZE; |
2bb4cd5c | 483 | blk_queue_max_discard_sectors(brd->brd_queue, UINT_MAX); |
b7c33571 NP |
484 | brd->brd_queue->limits.discard_zeroes_data = 1; |
485 | queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue); | |
937af5ec | 486 | disk = brd->brd_disk = alloc_disk(max_part); |
9db5579b NP |
487 | if (!disk) |
488 | goto out_free_queue; | |
489 | disk->major = RAMDISK_MAJOR; | |
937af5ec | 490 | disk->first_minor = i * max_part; |
9db5579b NP |
491 | disk->fops = &brd_fops; |
492 | disk->private_data = brd; | |
493 | disk->queue = brd->brd_queue; | |
937af5ec | 494 | disk->flags = GENHD_FL_EXT_DEVT; |
9db5579b NP |
495 | sprintf(disk->disk_name, "ram%d", i); |
496 | set_capacity(disk, rd_size * 2); | |
497 | ||
1647b9b9 DW |
498 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
499 | queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue); | |
500 | dax_dev = alloc_dax(brd, disk->disk_name, &brd_dax_ops); | |
501 | if (!dax_dev) | |
502 | goto out_free_inode; | |
503 | #endif | |
504 | ||
505 | ||
9db5579b NP |
506 | return brd; |
507 | ||
1647b9b9 DW |
508 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
509 | out_free_inode: | |
510 | kill_dax(dax_dev); | |
511 | put_dax(dax_dev); | |
512 | #endif | |
9db5579b NP |
513 | out_free_queue: |
514 | blk_cleanup_queue(brd->brd_queue); | |
515 | out_free_dev: | |
516 | kfree(brd); | |
517 | out: | |
518 | return NULL; | |
519 | } | |
520 | ||
521 | static void brd_free(struct brd_device *brd) | |
522 | { | |
523 | put_disk(brd->brd_disk); | |
524 | blk_cleanup_queue(brd->brd_queue); | |
525 | brd_free_pages(brd); | |
526 | kfree(brd); | |
527 | } | |
528 | ||
937af5ec | 529 | static struct brd_device *brd_init_one(int i, bool *new) |
9db5579b NP |
530 | { |
531 | struct brd_device *brd; | |
532 | ||
937af5ec | 533 | *new = false; |
9db5579b NP |
534 | list_for_each_entry(brd, &brd_devices, brd_list) { |
535 | if (brd->brd_number == i) | |
536 | goto out; | |
537 | } | |
538 | ||
539 | brd = brd_alloc(i); | |
540 | if (brd) { | |
541 | add_disk(brd->brd_disk); | |
542 | list_add_tail(&brd->brd_list, &brd_devices); | |
543 | } | |
937af5ec | 544 | *new = true; |
9db5579b NP |
545 | out: |
546 | return brd; | |
547 | } | |
548 | ||
549 | static void brd_del_one(struct brd_device *brd) | |
550 | { | |
551 | list_del(&brd->brd_list); | |
1647b9b9 DW |
552 | #ifdef CONFIG_BLK_DEV_RAM_DAX |
553 | kill_dax(brd->dax_dev); | |
554 | put_dax(brd->dax_dev); | |
555 | #endif | |
9db5579b NP |
556 | del_gendisk(brd->brd_disk); |
557 | brd_free(brd); | |
558 | } | |
559 | ||
560 | static struct kobject *brd_probe(dev_t dev, int *part, void *data) | |
561 | { | |
562 | struct brd_device *brd; | |
563 | struct kobject *kobj; | |
937af5ec | 564 | bool new; |
9db5579b NP |
565 | |
566 | mutex_lock(&brd_devices_mutex); | |
937af5ec | 567 | brd = brd_init_one(MINOR(dev) / max_part, &new); |
a207f593 | 568 | kobj = brd ? get_disk(brd->brd_disk) : NULL; |
9db5579b NP |
569 | mutex_unlock(&brd_devices_mutex); |
570 | ||
937af5ec BH |
571 | if (new) |
572 | *part = 0; | |
573 | ||
9db5579b NP |
574 | return kobj; |
575 | } | |
576 | ||
577 | static int __init brd_init(void) | |
578 | { | |
9db5579b | 579 | struct brd_device *brd, *next; |
937af5ec | 580 | int i; |
9db5579b NP |
581 | |
582 | /* | |
583 | * brd module now has a feature to instantiate underlying device | |
584 | * structure on-demand, provided that there is an access dev node. | |
9db5579b | 585 | * |
937af5ec BH |
586 | * (1) if rd_nr is specified, create that many upfront. else |
587 | * it defaults to CONFIG_BLK_DEV_RAM_COUNT | |
588 | * (2) User can further extend brd devices by create dev node themselves | |
589 | * and have kernel automatically instantiate actual device | |
590 | * on-demand. Example: | |
591 | * mknod /path/devnod_name b 1 X # 1 is the rd major | |
592 | * fdisk -l /path/devnod_name | |
593 | * If (X / max_part) was not already created it will be created | |
594 | * dynamically. | |
9db5579b | 595 | */ |
d7853d1f | 596 | |
9db5579b NP |
597 | if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) |
598 | return -EIO; | |
599 | ||
937af5ec BH |
600 | if (unlikely(!max_part)) |
601 | max_part = 1; | |
602 | ||
603 | for (i = 0; i < rd_nr; i++) { | |
9db5579b NP |
604 | brd = brd_alloc(i); |
605 | if (!brd) | |
606 | goto out_free; | |
607 | list_add_tail(&brd->brd_list, &brd_devices); | |
608 | } | |
609 | ||
610 | /* point of no return */ | |
611 | ||
612 | list_for_each_entry(brd, &brd_devices, brd_list) | |
613 | add_disk(brd->brd_disk); | |
614 | ||
937af5ec | 615 | blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS, |
9db5579b NP |
616 | THIS_MODULE, brd_probe, NULL, NULL); |
617 | ||
937af5ec | 618 | pr_info("brd: module loaded\n"); |
9db5579b NP |
619 | return 0; |
620 | ||
621 | out_free: | |
622 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { | |
623 | list_del(&brd->brd_list); | |
624 | brd_free(brd); | |
625 | } | |
c82f2966 | 626 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
9db5579b | 627 | |
937af5ec | 628 | pr_info("brd: module NOT loaded !!!\n"); |
9db5579b NP |
629 | return -ENOMEM; |
630 | } | |
631 | ||
632 | static void __exit brd_exit(void) | |
633 | { | |
9db5579b NP |
634 | struct brd_device *brd, *next; |
635 | ||
9db5579b NP |
636 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) |
637 | brd_del_one(brd); | |
638 | ||
937af5ec | 639 | blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS); |
9db5579b | 640 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
937af5ec BH |
641 | |
642 | pr_info("brd: module unloaded\n"); | |
9db5579b NP |
643 | } |
644 | ||
645 | module_init(brd_init); | |
646 | module_exit(brd_exit); | |
647 |