Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 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> |
| 18 | #include <linux/gfp.h> |
| 19 | #include <linux/radix-tree.h> |
| 20 | #include <linux/buffer_head.h> /* invalidate_bh_lrus() */ |
| 21 | |
| 22 | #include <asm/uaccess.h> |
| 23 | |
| 24 | #define SECTOR_SHIFT 9 |
| 25 | #define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) |
| 26 | #define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT) |
| 27 | |
| 28 | /* |
| 29 | * Each block ramdisk device has a radix_tree brd_pages of pages that stores |
| 30 | * the pages containing the block device's contents. A brd page's ->index is |
| 31 | * its offset in PAGE_SIZE units. This is similar to, but in no way connected |
| 32 | * with, the kernel's pagecache or buffer cache (which sit above our block |
| 33 | * device). |
| 34 | */ |
| 35 | struct brd_device { |
| 36 | int brd_number; |
| 37 | int brd_refcnt; |
| 38 | loff_t brd_offset; |
| 39 | loff_t brd_sizelimit; |
| 40 | unsigned brd_blocksize; |
| 41 | |
| 42 | struct request_queue *brd_queue; |
| 43 | struct gendisk *brd_disk; |
| 44 | struct list_head brd_list; |
| 45 | |
| 46 | /* |
| 47 | * Backing store of pages and lock to protect it. This is the contents |
| 48 | * of the block device. |
| 49 | */ |
| 50 | spinlock_t brd_lock; |
| 51 | struct radix_tree_root brd_pages; |
| 52 | }; |
| 53 | |
| 54 | /* |
| 55 | * Look up and return a brd's page for a given sector. |
| 56 | */ |
| 57 | static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) |
| 58 | { |
| 59 | pgoff_t idx; |
| 60 | struct page *page; |
| 61 | |
| 62 | /* |
| 63 | * The page lifetime is protected by the fact that we have opened the |
| 64 | * device node -- brd pages will never be deleted under us, so we |
| 65 | * don't need any further locking or refcounting. |
| 66 | * |
| 67 | * This is strictly true for the radix-tree nodes as well (ie. we |
| 68 | * don't actually need the rcu_read_lock()), however that is not a |
| 69 | * documented feature of the radix-tree API so it is better to be |
| 70 | * safe here (we don't have total exclusion from radix tree updates |
| 71 | * here, only deletes). |
| 72 | */ |
| 73 | rcu_read_lock(); |
| 74 | idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ |
| 75 | page = radix_tree_lookup(&brd->brd_pages, idx); |
| 76 | rcu_read_unlock(); |
| 77 | |
| 78 | BUG_ON(page && page->index != idx); |
| 79 | |
| 80 | return page; |
| 81 | } |
| 82 | |
| 83 | /* |
| 84 | * Look up and return a brd's page for a given sector. |
| 85 | * If one does not exist, allocate an empty page, and insert that. Then |
| 86 | * return it. |
| 87 | */ |
| 88 | static struct page *brd_insert_page(struct brd_device *brd, sector_t sector) |
| 89 | { |
| 90 | pgoff_t idx; |
| 91 | struct page *page; |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 92 | gfp_t gfp_flags; |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 93 | |
| 94 | page = brd_lookup_page(brd, sector); |
| 95 | if (page) |
| 96 | return page; |
| 97 | |
| 98 | /* |
| 99 | * Must use NOIO because we don't want to recurse back into the |
| 100 | * block or filesystem layers from page reclaim. |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 101 | * |
| 102 | * Cannot support XIP and highmem, because our ->direct_access |
| 103 | * routine for XIP must return memory that is always addressable. |
| 104 | * If XIP was reworked to use pfns and kmap throughout, this |
| 105 | * restriction might be able to be lifted. |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 106 | */ |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 107 | gfp_flags = GFP_NOIO | __GFP_ZERO; |
| 108 | #ifndef CONFIG_BLK_DEV_XIP |
| 109 | gfp_flags |= __GFP_HIGHMEM; |
| 110 | #endif |
Petr Tesarik | 26defe3 | 2008-04-22 05:36:52 +0200 | [diff] [blame] | 111 | page = alloc_page(gfp_flags); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 112 | if (!page) |
| 113 | return NULL; |
| 114 | |
| 115 | if (radix_tree_preload(GFP_NOIO)) { |
| 116 | __free_page(page); |
| 117 | return NULL; |
| 118 | } |
| 119 | |
| 120 | spin_lock(&brd->brd_lock); |
| 121 | idx = sector >> PAGE_SECTORS_SHIFT; |
| 122 | if (radix_tree_insert(&brd->brd_pages, idx, page)) { |
| 123 | __free_page(page); |
| 124 | page = radix_tree_lookup(&brd->brd_pages, idx); |
| 125 | BUG_ON(!page); |
| 126 | BUG_ON(page->index != idx); |
| 127 | } else |
| 128 | page->index = idx; |
| 129 | spin_unlock(&brd->brd_lock); |
| 130 | |
| 131 | radix_tree_preload_end(); |
| 132 | |
| 133 | return page; |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Free all backing store pages and radix tree. This must only be called when |
| 138 | * there are no other users of the device. |
| 139 | */ |
| 140 | #define FREE_BATCH 16 |
| 141 | static void brd_free_pages(struct brd_device *brd) |
| 142 | { |
| 143 | unsigned long pos = 0; |
| 144 | struct page *pages[FREE_BATCH]; |
| 145 | int nr_pages; |
| 146 | |
| 147 | do { |
| 148 | int i; |
| 149 | |
| 150 | nr_pages = radix_tree_gang_lookup(&brd->brd_pages, |
| 151 | (void **)pages, pos, FREE_BATCH); |
| 152 | |
| 153 | for (i = 0; i < nr_pages; i++) { |
| 154 | void *ret; |
| 155 | |
| 156 | BUG_ON(pages[i]->index < pos); |
| 157 | pos = pages[i]->index; |
| 158 | ret = radix_tree_delete(&brd->brd_pages, pos); |
| 159 | BUG_ON(!ret || ret != pages[i]); |
| 160 | __free_page(pages[i]); |
| 161 | } |
| 162 | |
| 163 | pos++; |
| 164 | |
| 165 | /* |
| 166 | * This assumes radix_tree_gang_lookup always returns as |
| 167 | * many pages as possible. If the radix-tree code changes, |
| 168 | * so will this have to. |
| 169 | */ |
| 170 | } while (nr_pages == FREE_BATCH); |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * copy_to_brd_setup must be called before copy_to_brd. It may sleep. |
| 175 | */ |
| 176 | static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) |
| 177 | { |
| 178 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; |
| 179 | size_t copy; |
| 180 | |
| 181 | copy = min_t(size_t, n, PAGE_SIZE - offset); |
| 182 | if (!brd_insert_page(brd, sector)) |
| 183 | return -ENOMEM; |
| 184 | if (copy < n) { |
| 185 | sector += copy >> SECTOR_SHIFT; |
| 186 | if (!brd_insert_page(brd, sector)) |
| 187 | return -ENOMEM; |
| 188 | } |
| 189 | return 0; |
| 190 | } |
| 191 | |
| 192 | /* |
| 193 | * Copy n bytes from src to the brd starting at sector. Does not sleep. |
| 194 | */ |
| 195 | static void copy_to_brd(struct brd_device *brd, const void *src, |
| 196 | sector_t sector, size_t n) |
| 197 | { |
| 198 | struct page *page; |
| 199 | void *dst; |
| 200 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; |
| 201 | size_t copy; |
| 202 | |
| 203 | copy = min_t(size_t, n, PAGE_SIZE - offset); |
| 204 | page = brd_lookup_page(brd, sector); |
| 205 | BUG_ON(!page); |
| 206 | |
| 207 | dst = kmap_atomic(page, KM_USER1); |
| 208 | memcpy(dst + offset, src, copy); |
| 209 | kunmap_atomic(dst, KM_USER1); |
| 210 | |
| 211 | if (copy < n) { |
| 212 | src += copy; |
| 213 | sector += copy >> SECTOR_SHIFT; |
| 214 | copy = n - copy; |
| 215 | page = brd_lookup_page(brd, sector); |
| 216 | BUG_ON(!page); |
| 217 | |
| 218 | dst = kmap_atomic(page, KM_USER1); |
| 219 | memcpy(dst, src, copy); |
| 220 | kunmap_atomic(dst, KM_USER1); |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | /* |
| 225 | * Copy n bytes to dst from the brd starting at sector. Does not sleep. |
| 226 | */ |
| 227 | static void copy_from_brd(void *dst, struct brd_device *brd, |
| 228 | sector_t sector, size_t n) |
| 229 | { |
| 230 | struct page *page; |
| 231 | void *src; |
| 232 | unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; |
| 233 | size_t copy; |
| 234 | |
| 235 | copy = min_t(size_t, n, PAGE_SIZE - offset); |
| 236 | page = brd_lookup_page(brd, sector); |
| 237 | if (page) { |
| 238 | src = kmap_atomic(page, KM_USER1); |
| 239 | memcpy(dst, src + offset, copy); |
| 240 | kunmap_atomic(src, KM_USER1); |
| 241 | } else |
| 242 | memset(dst, 0, copy); |
| 243 | |
| 244 | if (copy < n) { |
| 245 | dst += copy; |
| 246 | sector += copy >> SECTOR_SHIFT; |
| 247 | copy = n - copy; |
| 248 | page = brd_lookup_page(brd, sector); |
| 249 | if (page) { |
| 250 | src = kmap_atomic(page, KM_USER1); |
| 251 | memcpy(dst, src, copy); |
| 252 | kunmap_atomic(src, KM_USER1); |
| 253 | } else |
| 254 | memset(dst, 0, copy); |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | /* |
| 259 | * Process a single bvec of a bio. |
| 260 | */ |
| 261 | static int brd_do_bvec(struct brd_device *brd, struct page *page, |
| 262 | unsigned int len, unsigned int off, int rw, |
| 263 | sector_t sector) |
| 264 | { |
| 265 | void *mem; |
| 266 | int err = 0; |
| 267 | |
| 268 | if (rw != READ) { |
| 269 | err = copy_to_brd_setup(brd, sector, len); |
| 270 | if (err) |
| 271 | goto out; |
| 272 | } |
| 273 | |
| 274 | mem = kmap_atomic(page, KM_USER0); |
| 275 | if (rw == READ) { |
| 276 | copy_from_brd(mem + off, brd, sector, len); |
| 277 | flush_dcache_page(page); |
Nick Piggin | c2572f2 | 2009-04-15 10:32:07 +0200 | [diff] [blame] | 278 | } else { |
| 279 | flush_dcache_page(page); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 280 | copy_to_brd(brd, mem + off, sector, len); |
Nick Piggin | c2572f2 | 2009-04-15 10:32:07 +0200 | [diff] [blame] | 281 | } |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 282 | kunmap_atomic(mem, KM_USER0); |
| 283 | |
| 284 | out: |
| 285 | return err; |
| 286 | } |
| 287 | |
| 288 | static int brd_make_request(struct request_queue *q, struct bio *bio) |
| 289 | { |
| 290 | struct block_device *bdev = bio->bi_bdev; |
| 291 | struct brd_device *brd = bdev->bd_disk->private_data; |
| 292 | int rw; |
| 293 | struct bio_vec *bvec; |
| 294 | sector_t sector; |
| 295 | int i; |
| 296 | int err = -EIO; |
| 297 | |
| 298 | sector = bio->bi_sector; |
| 299 | if (sector + (bio->bi_size >> SECTOR_SHIFT) > |
| 300 | get_capacity(bdev->bd_disk)) |
| 301 | goto out; |
| 302 | |
| 303 | rw = bio_rw(bio); |
| 304 | if (rw == READA) |
| 305 | rw = READ; |
| 306 | |
| 307 | bio_for_each_segment(bvec, bio, i) { |
| 308 | unsigned int len = bvec->bv_len; |
| 309 | err = brd_do_bvec(brd, bvec->bv_page, len, |
| 310 | bvec->bv_offset, rw, sector); |
| 311 | if (err) |
| 312 | break; |
| 313 | sector += len >> SECTOR_SHIFT; |
| 314 | } |
| 315 | |
| 316 | out: |
| 317 | bio_endio(bio, err); |
| 318 | |
| 319 | return 0; |
| 320 | } |
| 321 | |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 322 | #ifdef CONFIG_BLK_DEV_XIP |
| 323 | static int brd_direct_access (struct block_device *bdev, sector_t sector, |
Jared Hulbert | 30afcb4 | 2008-04-28 02:13:02 -0700 | [diff] [blame] | 324 | void **kaddr, unsigned long *pfn) |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 325 | { |
| 326 | struct brd_device *brd = bdev->bd_disk->private_data; |
| 327 | struct page *page; |
| 328 | |
| 329 | if (!brd) |
| 330 | return -ENODEV; |
| 331 | if (sector & (PAGE_SECTORS-1)) |
| 332 | return -EINVAL; |
| 333 | if (sector + PAGE_SECTORS > get_capacity(bdev->bd_disk)) |
| 334 | return -ERANGE; |
| 335 | page = brd_insert_page(brd, sector); |
| 336 | if (!page) |
| 337 | return -ENOMEM; |
Jared Hulbert | 30afcb4 | 2008-04-28 02:13:02 -0700 | [diff] [blame] | 338 | *kaddr = page_address(page); |
| 339 | *pfn = page_to_pfn(page); |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 340 | |
| 341 | return 0; |
| 342 | } |
| 343 | #endif |
| 344 | |
Al Viro | 2b9ecd0 | 2008-03-02 09:24:35 -0500 | [diff] [blame] | 345 | static int brd_ioctl(struct block_device *bdev, fmode_t mode, |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 346 | unsigned int cmd, unsigned long arg) |
| 347 | { |
| 348 | int error; |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 349 | struct brd_device *brd = bdev->bd_disk->private_data; |
| 350 | |
| 351 | if (cmd != BLKFLSBUF) |
| 352 | return -ENOTTY; |
| 353 | |
| 354 | /* |
| 355 | * ram device BLKFLSBUF has special semantics, we want to actually |
| 356 | * release and destroy the ramdisk data. |
| 357 | */ |
| 358 | mutex_lock(&bdev->bd_mutex); |
| 359 | error = -EBUSY; |
| 360 | if (bdev->bd_openers <= 1) { |
| 361 | /* |
| 362 | * Invalidate the cache first, so it isn't written |
| 363 | * back to the device. |
| 364 | * |
| 365 | * Another thread might instantiate more buffercache here, |
| 366 | * but there is not much we can do to close that race. |
| 367 | */ |
| 368 | invalidate_bh_lrus(); |
| 369 | truncate_inode_pages(bdev->bd_inode->i_mapping, 0); |
| 370 | brd_free_pages(brd); |
| 371 | error = 0; |
| 372 | } |
| 373 | mutex_unlock(&bdev->bd_mutex); |
| 374 | |
| 375 | return error; |
| 376 | } |
| 377 | |
| 378 | static struct block_device_operations brd_fops = { |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 379 | .owner = THIS_MODULE, |
Al Viro | 2b9ecd0 | 2008-03-02 09:24:35 -0500 | [diff] [blame] | 380 | .locked_ioctl = brd_ioctl, |
Nick Piggin | 75acb9c | 2008-02-08 04:19:50 -0800 | [diff] [blame] | 381 | #ifdef CONFIG_BLK_DEV_XIP |
| 382 | .direct_access = brd_direct_access, |
| 383 | #endif |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 384 | }; |
| 385 | |
| 386 | /* |
| 387 | * And now the modules code and kernel interface. |
| 388 | */ |
| 389 | static int rd_nr; |
| 390 | int rd_size = CONFIG_BLK_DEV_RAM_SIZE; |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 391 | static int max_part; |
| 392 | static int part_shift; |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 393 | module_param(rd_nr, int, 0); |
| 394 | MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); |
| 395 | module_param(rd_size, int, 0); |
| 396 | MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 397 | module_param(max_part, int, 0); |
| 398 | MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk"); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 399 | MODULE_LICENSE("GPL"); |
| 400 | MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); |
Nick Piggin | efedf51 | 2008-06-04 17:18:42 +0200 | [diff] [blame] | 401 | MODULE_ALIAS("rd"); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 402 | |
| 403 | #ifndef MODULE |
| 404 | /* Legacy boot options - nonmodular */ |
| 405 | static int __init ramdisk_size(char *str) |
| 406 | { |
| 407 | rd_size = simple_strtol(str, NULL, 0); |
| 408 | return 1; |
| 409 | } |
Robert P. J. Day | 1adbee5 | 2009-06-10 12:57:08 -0700 | [diff] [blame] | 410 | __setup("ramdisk_size=", ramdisk_size); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 411 | #endif |
| 412 | |
| 413 | /* |
| 414 | * The device scheme is derived from loop.c. Keep them in synch where possible |
| 415 | * (should share code eventually). |
| 416 | */ |
| 417 | static LIST_HEAD(brd_devices); |
| 418 | static DEFINE_MUTEX(brd_devices_mutex); |
| 419 | |
| 420 | static struct brd_device *brd_alloc(int i) |
| 421 | { |
| 422 | struct brd_device *brd; |
| 423 | struct gendisk *disk; |
| 424 | |
| 425 | brd = kzalloc(sizeof(*brd), GFP_KERNEL); |
| 426 | if (!brd) |
| 427 | goto out; |
| 428 | brd->brd_number = i; |
| 429 | spin_lock_init(&brd->brd_lock); |
| 430 | INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); |
| 431 | |
| 432 | brd->brd_queue = blk_alloc_queue(GFP_KERNEL); |
| 433 | if (!brd->brd_queue) |
| 434 | goto out_free_dev; |
| 435 | blk_queue_make_request(brd->brd_queue, brd_make_request); |
Nick Piggin | dfbc475 | 2009-04-15 10:27:07 +0200 | [diff] [blame] | 436 | blk_queue_ordered(brd->brd_queue, QUEUE_ORDERED_TAG, NULL); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 437 | blk_queue_max_sectors(brd->brd_queue, 1024); |
| 438 | blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); |
| 439 | |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 440 | disk = brd->brd_disk = alloc_disk(1 << part_shift); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 441 | if (!disk) |
| 442 | goto out_free_queue; |
| 443 | disk->major = RAMDISK_MAJOR; |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 444 | disk->first_minor = i << part_shift; |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 445 | disk->fops = &brd_fops; |
| 446 | disk->private_data = brd; |
| 447 | disk->queue = brd->brd_queue; |
Marcin Krol | 53978d0 | 2008-05-23 13:04:46 -0700 | [diff] [blame] | 448 | disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO; |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 449 | sprintf(disk->disk_name, "ram%d", i); |
| 450 | set_capacity(disk, rd_size * 2); |
| 451 | |
| 452 | return brd; |
| 453 | |
| 454 | out_free_queue: |
| 455 | blk_cleanup_queue(brd->brd_queue); |
| 456 | out_free_dev: |
| 457 | kfree(brd); |
| 458 | out: |
| 459 | return NULL; |
| 460 | } |
| 461 | |
| 462 | static void brd_free(struct brd_device *brd) |
| 463 | { |
| 464 | put_disk(brd->brd_disk); |
| 465 | blk_cleanup_queue(brd->brd_queue); |
| 466 | brd_free_pages(brd); |
| 467 | kfree(brd); |
| 468 | } |
| 469 | |
| 470 | static struct brd_device *brd_init_one(int i) |
| 471 | { |
| 472 | struct brd_device *brd; |
| 473 | |
| 474 | list_for_each_entry(brd, &brd_devices, brd_list) { |
| 475 | if (brd->brd_number == i) |
| 476 | goto out; |
| 477 | } |
| 478 | |
| 479 | brd = brd_alloc(i); |
| 480 | if (brd) { |
| 481 | add_disk(brd->brd_disk); |
| 482 | list_add_tail(&brd->brd_list, &brd_devices); |
| 483 | } |
| 484 | out: |
| 485 | return brd; |
| 486 | } |
| 487 | |
| 488 | static void brd_del_one(struct brd_device *brd) |
| 489 | { |
| 490 | list_del(&brd->brd_list); |
| 491 | del_gendisk(brd->brd_disk); |
| 492 | brd_free(brd); |
| 493 | } |
| 494 | |
| 495 | static struct kobject *brd_probe(dev_t dev, int *part, void *data) |
| 496 | { |
| 497 | struct brd_device *brd; |
| 498 | struct kobject *kobj; |
| 499 | |
| 500 | mutex_lock(&brd_devices_mutex); |
| 501 | brd = brd_init_one(dev & MINORMASK); |
| 502 | kobj = brd ? get_disk(brd->brd_disk) : ERR_PTR(-ENOMEM); |
| 503 | mutex_unlock(&brd_devices_mutex); |
| 504 | |
| 505 | *part = 0; |
| 506 | return kobj; |
| 507 | } |
| 508 | |
| 509 | static int __init brd_init(void) |
| 510 | { |
| 511 | int i, nr; |
| 512 | unsigned long range; |
| 513 | struct brd_device *brd, *next; |
| 514 | |
| 515 | /* |
| 516 | * brd module now has a feature to instantiate underlying device |
| 517 | * structure on-demand, provided that there is an access dev node. |
| 518 | * However, this will not work well with user space tool that doesn't |
| 519 | * know about such "feature". In order to not break any existing |
| 520 | * tool, we do the following: |
| 521 | * |
| 522 | * (1) if rd_nr is specified, create that many upfront, and this |
| 523 | * also becomes a hard limit. |
| 524 | * (2) if rd_nr is not specified, create 1 rd device on module |
| 525 | * load, user can further extend brd device by create dev node |
| 526 | * themselves and have kernel automatically instantiate actual |
| 527 | * device on-demand. |
| 528 | */ |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 529 | |
| 530 | part_shift = 0; |
| 531 | if (max_part > 0) |
| 532 | part_shift = fls(max_part); |
| 533 | |
| 534 | if (rd_nr > 1UL << (MINORBITS - part_shift)) |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 535 | return -EINVAL; |
| 536 | |
| 537 | if (rd_nr) { |
| 538 | nr = rd_nr; |
| 539 | range = rd_nr; |
| 540 | } else { |
| 541 | nr = CONFIG_BLK_DEV_RAM_COUNT; |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 542 | range = 1UL << (MINORBITS - part_shift); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 543 | } |
| 544 | |
| 545 | if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) |
| 546 | return -EIO; |
| 547 | |
| 548 | for (i = 0; i < nr; i++) { |
| 549 | brd = brd_alloc(i); |
| 550 | if (!brd) |
| 551 | goto out_free; |
| 552 | list_add_tail(&brd->brd_list, &brd_devices); |
| 553 | } |
| 554 | |
| 555 | /* point of no return */ |
| 556 | |
| 557 | list_for_each_entry(brd, &brd_devices, brd_list) |
| 558 | add_disk(brd->brd_disk); |
| 559 | |
| 560 | blk_register_region(MKDEV(RAMDISK_MAJOR, 0), range, |
| 561 | THIS_MODULE, brd_probe, NULL, NULL); |
| 562 | |
| 563 | printk(KERN_INFO "brd: module loaded\n"); |
| 564 | return 0; |
| 565 | |
| 566 | out_free: |
| 567 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { |
| 568 | list_del(&brd->brd_list); |
| 569 | brd_free(brd); |
| 570 | } |
Akinobu Mita | c82f296 | 2008-08-20 14:09:09 -0700 | [diff] [blame] | 571 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 572 | |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 573 | return -ENOMEM; |
| 574 | } |
| 575 | |
| 576 | static void __exit brd_exit(void) |
| 577 | { |
| 578 | unsigned long range; |
| 579 | struct brd_device *brd, *next; |
| 580 | |
Laurent Vivier | d7853d1 | 2008-04-30 00:55:06 -0700 | [diff] [blame] | 581 | range = rd_nr ? rd_nr : 1UL << (MINORBITS - part_shift); |
Nick Piggin | 9db5579 | 2008-02-08 04:19:49 -0800 | [diff] [blame] | 582 | |
| 583 | list_for_each_entry_safe(brd, next, &brd_devices, brd_list) |
| 584 | brd_del_one(brd); |
| 585 | |
| 586 | blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), range); |
| 587 | unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); |
| 588 | } |
| 589 | |
| 590 | module_init(brd_init); |
| 591 | module_exit(brd_exit); |
| 592 | |