| 1 | /* |
| 2 | * Copyright (C) 2009-2011 Red Hat, Inc. |
| 3 | * |
| 4 | * Author: Mikulas Patocka <mpatocka@redhat.com> |
| 5 | * |
| 6 | * This file is released under the GPL. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/dm-bufio.h> |
| 10 | |
| 11 | #include <linux/device-mapper.h> |
| 12 | #include <linux/dm-io.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/sched/mm.h> |
| 15 | #include <linux/jiffies.h> |
| 16 | #include <linux/vmalloc.h> |
| 17 | #include <linux/shrinker.h> |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/rbtree.h> |
| 20 | #include <linux/stacktrace.h> |
| 21 | |
| 22 | #define DM_MSG_PREFIX "bufio" |
| 23 | |
| 24 | /* |
| 25 | * Memory management policy: |
| 26 | * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory |
| 27 | * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower). |
| 28 | * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers. |
| 29 | * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT |
| 30 | * dirty buffers. |
| 31 | */ |
| 32 | #define DM_BUFIO_MIN_BUFFERS 8 |
| 33 | |
| 34 | #define DM_BUFIO_MEMORY_PERCENT 2 |
| 35 | #define DM_BUFIO_VMALLOC_PERCENT 25 |
| 36 | #define DM_BUFIO_WRITEBACK_PERCENT 75 |
| 37 | |
| 38 | /* |
| 39 | * Check buffer ages in this interval (seconds) |
| 40 | */ |
| 41 | #define DM_BUFIO_WORK_TIMER_SECS 30 |
| 42 | |
| 43 | /* |
| 44 | * Free buffers when they are older than this (seconds) |
| 45 | */ |
| 46 | #define DM_BUFIO_DEFAULT_AGE_SECS 300 |
| 47 | |
| 48 | /* |
| 49 | * The nr of bytes of cached data to keep around. |
| 50 | */ |
| 51 | #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024) |
| 52 | |
| 53 | /* |
| 54 | * The number of bvec entries that are embedded directly in the buffer. |
| 55 | * If the chunk size is larger, dm-io is used to do the io. |
| 56 | */ |
| 57 | #define DM_BUFIO_INLINE_VECS 16 |
| 58 | |
| 59 | /* |
| 60 | * Don't try to use alloc_pages for blocks larger than this. |
| 61 | * For explanation, see alloc_buffer_data below. |
| 62 | */ |
| 63 | #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1)) |
| 64 | |
| 65 | /* |
| 66 | * Align buffer writes to this boundary. |
| 67 | * Tests show that SSDs have the highest IOPS when using 4k writes. |
| 68 | */ |
| 69 | #define DM_BUFIO_WRITE_ALIGN 4096 |
| 70 | |
| 71 | /* |
| 72 | * dm_buffer->list_mode |
| 73 | */ |
| 74 | #define LIST_CLEAN 0 |
| 75 | #define LIST_DIRTY 1 |
| 76 | #define LIST_SIZE 2 |
| 77 | |
| 78 | /* |
| 79 | * Linking of buffers: |
| 80 | * All buffers are linked to cache_hash with their hash_list field. |
| 81 | * |
| 82 | * Clean buffers that are not being written (B_WRITING not set) |
| 83 | * are linked to lru[LIST_CLEAN] with their lru_list field. |
| 84 | * |
| 85 | * Dirty and clean buffers that are being written are linked to |
| 86 | * lru[LIST_DIRTY] with their lru_list field. When the write |
| 87 | * finishes, the buffer cannot be relinked immediately (because we |
| 88 | * are in an interrupt context and relinking requires process |
| 89 | * context), so some clean-not-writing buffers can be held on |
| 90 | * dirty_lru too. They are later added to lru in the process |
| 91 | * context. |
| 92 | */ |
| 93 | struct dm_bufio_client { |
| 94 | struct mutex lock; |
| 95 | |
| 96 | struct list_head lru[LIST_SIZE]; |
| 97 | unsigned long n_buffers[LIST_SIZE]; |
| 98 | |
| 99 | struct block_device *bdev; |
| 100 | unsigned block_size; |
| 101 | unsigned char sectors_per_block_bits; |
| 102 | unsigned char pages_per_block_bits; |
| 103 | unsigned aux_size; |
| 104 | void (*alloc_callback)(struct dm_buffer *); |
| 105 | void (*write_callback)(struct dm_buffer *); |
| 106 | |
| 107 | struct kmem_cache *slab_cache; |
| 108 | struct dm_io_client *dm_io; |
| 109 | |
| 110 | struct list_head reserved_buffers; |
| 111 | unsigned need_reserved_buffers; |
| 112 | |
| 113 | unsigned minimum_buffers; |
| 114 | |
| 115 | struct rb_root buffer_tree; |
| 116 | wait_queue_head_t free_buffer_wait; |
| 117 | |
| 118 | sector_t start; |
| 119 | |
| 120 | int async_write_error; |
| 121 | |
| 122 | struct list_head client_list; |
| 123 | struct shrinker shrinker; |
| 124 | }; |
| 125 | |
| 126 | /* |
| 127 | * Buffer state bits. |
| 128 | */ |
| 129 | #define B_READING 0 |
| 130 | #define B_WRITING 1 |
| 131 | #define B_DIRTY 2 |
| 132 | |
| 133 | /* |
| 134 | * Describes how the block was allocated: |
| 135 | * kmem_cache_alloc(), __get_free_pages() or vmalloc(). |
| 136 | * See the comment at alloc_buffer_data. |
| 137 | */ |
| 138 | enum data_mode { |
| 139 | DATA_MODE_SLAB = 0, |
| 140 | DATA_MODE_GET_FREE_PAGES = 1, |
| 141 | DATA_MODE_VMALLOC = 2, |
| 142 | DATA_MODE_LIMIT = 3 |
| 143 | }; |
| 144 | |
| 145 | struct dm_buffer { |
| 146 | struct rb_node node; |
| 147 | struct list_head lru_list; |
| 148 | sector_t block; |
| 149 | void *data; |
| 150 | unsigned char data_mode; /* DATA_MODE_* */ |
| 151 | unsigned char list_mode; /* LIST_* */ |
| 152 | blk_status_t read_error; |
| 153 | blk_status_t write_error; |
| 154 | unsigned hold_count; |
| 155 | unsigned long state; |
| 156 | unsigned long last_accessed; |
| 157 | unsigned dirty_start; |
| 158 | unsigned dirty_end; |
| 159 | unsigned write_start; |
| 160 | unsigned write_end; |
| 161 | struct dm_bufio_client *c; |
| 162 | struct list_head write_list; |
| 163 | struct bio bio; |
| 164 | struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS]; |
| 165 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 166 | #define MAX_STACK 10 |
| 167 | struct stack_trace stack_trace; |
| 168 | unsigned long stack_entries[MAX_STACK]; |
| 169 | #endif |
| 170 | }; |
| 171 | |
| 172 | /*----------------------------------------------------------------*/ |
| 173 | |
| 174 | #define dm_bufio_in_request() (!!current->bio_list) |
| 175 | |
| 176 | static void dm_bufio_lock(struct dm_bufio_client *c) |
| 177 | { |
| 178 | mutex_lock_nested(&c->lock, dm_bufio_in_request()); |
| 179 | } |
| 180 | |
| 181 | static int dm_bufio_trylock(struct dm_bufio_client *c) |
| 182 | { |
| 183 | return mutex_trylock(&c->lock); |
| 184 | } |
| 185 | |
| 186 | static void dm_bufio_unlock(struct dm_bufio_client *c) |
| 187 | { |
| 188 | mutex_unlock(&c->lock); |
| 189 | } |
| 190 | |
| 191 | /*----------------------------------------------------------------*/ |
| 192 | |
| 193 | /* |
| 194 | * Default cache size: available memory divided by the ratio. |
| 195 | */ |
| 196 | static unsigned long dm_bufio_default_cache_size; |
| 197 | |
| 198 | /* |
| 199 | * Total cache size set by the user. |
| 200 | */ |
| 201 | static unsigned long dm_bufio_cache_size; |
| 202 | |
| 203 | /* |
| 204 | * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change |
| 205 | * at any time. If it disagrees, the user has changed cache size. |
| 206 | */ |
| 207 | static unsigned long dm_bufio_cache_size_latch; |
| 208 | |
| 209 | static DEFINE_SPINLOCK(param_spinlock); |
| 210 | |
| 211 | /* |
| 212 | * Buffers are freed after this timeout |
| 213 | */ |
| 214 | static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; |
| 215 | static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES; |
| 216 | |
| 217 | static unsigned long dm_bufio_peak_allocated; |
| 218 | static unsigned long dm_bufio_allocated_kmem_cache; |
| 219 | static unsigned long dm_bufio_allocated_get_free_pages; |
| 220 | static unsigned long dm_bufio_allocated_vmalloc; |
| 221 | static unsigned long dm_bufio_current_allocated; |
| 222 | |
| 223 | /*----------------------------------------------------------------*/ |
| 224 | |
| 225 | /* |
| 226 | * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count |
| 227 | */ |
| 228 | static unsigned long dm_bufio_cache_size_per_client; |
| 229 | |
| 230 | /* |
| 231 | * The current number of clients. |
| 232 | */ |
| 233 | static int dm_bufio_client_count; |
| 234 | |
| 235 | /* |
| 236 | * The list of all clients. |
| 237 | */ |
| 238 | static LIST_HEAD(dm_bufio_all_clients); |
| 239 | |
| 240 | /* |
| 241 | * This mutex protects dm_bufio_cache_size_latch, |
| 242 | * dm_bufio_cache_size_per_client and dm_bufio_client_count |
| 243 | */ |
| 244 | static DEFINE_MUTEX(dm_bufio_clients_lock); |
| 245 | |
| 246 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 247 | static void buffer_record_stack(struct dm_buffer *b) |
| 248 | { |
| 249 | b->stack_trace.nr_entries = 0; |
| 250 | b->stack_trace.max_entries = MAX_STACK; |
| 251 | b->stack_trace.entries = b->stack_entries; |
| 252 | b->stack_trace.skip = 2; |
| 253 | save_stack_trace(&b->stack_trace); |
| 254 | } |
| 255 | #endif |
| 256 | |
| 257 | /*---------------------------------------------------------------- |
| 258 | * A red/black tree acts as an index for all the buffers. |
| 259 | *--------------------------------------------------------------*/ |
| 260 | static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) |
| 261 | { |
| 262 | struct rb_node *n = c->buffer_tree.rb_node; |
| 263 | struct dm_buffer *b; |
| 264 | |
| 265 | while (n) { |
| 266 | b = container_of(n, struct dm_buffer, node); |
| 267 | |
| 268 | if (b->block == block) |
| 269 | return b; |
| 270 | |
| 271 | n = (b->block < block) ? n->rb_left : n->rb_right; |
| 272 | } |
| 273 | |
| 274 | return NULL; |
| 275 | } |
| 276 | |
| 277 | static void __insert(struct dm_bufio_client *c, struct dm_buffer *b) |
| 278 | { |
| 279 | struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL; |
| 280 | struct dm_buffer *found; |
| 281 | |
| 282 | while (*new) { |
| 283 | found = container_of(*new, struct dm_buffer, node); |
| 284 | |
| 285 | if (found->block == b->block) { |
| 286 | BUG_ON(found != b); |
| 287 | return; |
| 288 | } |
| 289 | |
| 290 | parent = *new; |
| 291 | new = (found->block < b->block) ? |
| 292 | &((*new)->rb_left) : &((*new)->rb_right); |
| 293 | } |
| 294 | |
| 295 | rb_link_node(&b->node, parent, new); |
| 296 | rb_insert_color(&b->node, &c->buffer_tree); |
| 297 | } |
| 298 | |
| 299 | static void __remove(struct dm_bufio_client *c, struct dm_buffer *b) |
| 300 | { |
| 301 | rb_erase(&b->node, &c->buffer_tree); |
| 302 | } |
| 303 | |
| 304 | /*----------------------------------------------------------------*/ |
| 305 | |
| 306 | static void adjust_total_allocated(unsigned char data_mode, long diff) |
| 307 | { |
| 308 | static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { |
| 309 | &dm_bufio_allocated_kmem_cache, |
| 310 | &dm_bufio_allocated_get_free_pages, |
| 311 | &dm_bufio_allocated_vmalloc, |
| 312 | }; |
| 313 | |
| 314 | spin_lock(¶m_spinlock); |
| 315 | |
| 316 | *class_ptr[data_mode] += diff; |
| 317 | |
| 318 | dm_bufio_current_allocated += diff; |
| 319 | |
| 320 | if (dm_bufio_current_allocated > dm_bufio_peak_allocated) |
| 321 | dm_bufio_peak_allocated = dm_bufio_current_allocated; |
| 322 | |
| 323 | spin_unlock(¶m_spinlock); |
| 324 | } |
| 325 | |
| 326 | /* |
| 327 | * Change the number of clients and recalculate per-client limit. |
| 328 | */ |
| 329 | static void __cache_size_refresh(void) |
| 330 | { |
| 331 | BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); |
| 332 | BUG_ON(dm_bufio_client_count < 0); |
| 333 | |
| 334 | dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size); |
| 335 | |
| 336 | /* |
| 337 | * Use default if set to 0 and report the actual cache size used. |
| 338 | */ |
| 339 | if (!dm_bufio_cache_size_latch) { |
| 340 | (void)cmpxchg(&dm_bufio_cache_size, 0, |
| 341 | dm_bufio_default_cache_size); |
| 342 | dm_bufio_cache_size_latch = dm_bufio_default_cache_size; |
| 343 | } |
| 344 | |
| 345 | dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / |
| 346 | (dm_bufio_client_count ? : 1); |
| 347 | } |
| 348 | |
| 349 | /* |
| 350 | * Allocating buffer data. |
| 351 | * |
| 352 | * Small buffers are allocated with kmem_cache, to use space optimally. |
| 353 | * |
| 354 | * For large buffers, we choose between get_free_pages and vmalloc. |
| 355 | * Each has advantages and disadvantages. |
| 356 | * |
| 357 | * __get_free_pages can randomly fail if the memory is fragmented. |
| 358 | * __vmalloc won't randomly fail, but vmalloc space is limited (it may be |
| 359 | * as low as 128M) so using it for caching is not appropriate. |
| 360 | * |
| 361 | * If the allocation may fail we use __get_free_pages. Memory fragmentation |
| 362 | * won't have a fatal effect here, but it just causes flushes of some other |
| 363 | * buffers and more I/O will be performed. Don't use __get_free_pages if it |
| 364 | * always fails (i.e. order >= MAX_ORDER). |
| 365 | * |
| 366 | * If the allocation shouldn't fail we use __vmalloc. This is only for the |
| 367 | * initial reserve allocation, so there's no risk of wasting all vmalloc |
| 368 | * space. |
| 369 | */ |
| 370 | static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, |
| 371 | unsigned char *data_mode) |
| 372 | { |
| 373 | if (unlikely(c->slab_cache != NULL)) { |
| 374 | *data_mode = DATA_MODE_SLAB; |
| 375 | return kmem_cache_alloc(c->slab_cache, gfp_mask); |
| 376 | } |
| 377 | |
| 378 | if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT && |
| 379 | gfp_mask & __GFP_NORETRY) { |
| 380 | *data_mode = DATA_MODE_GET_FREE_PAGES; |
| 381 | return (void *)__get_free_pages(gfp_mask, |
| 382 | c->pages_per_block_bits); |
| 383 | } |
| 384 | |
| 385 | *data_mode = DATA_MODE_VMALLOC; |
| 386 | |
| 387 | /* |
| 388 | * __vmalloc allocates the data pages and auxiliary structures with |
| 389 | * gfp_flags that were specified, but pagetables are always allocated |
| 390 | * with GFP_KERNEL, no matter what was specified as gfp_mask. |
| 391 | * |
| 392 | * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that |
| 393 | * all allocations done by this process (including pagetables) are done |
| 394 | * as if GFP_NOIO was specified. |
| 395 | */ |
| 396 | if (gfp_mask & __GFP_NORETRY) { |
| 397 | unsigned noio_flag = memalloc_noio_save(); |
| 398 | void *ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); |
| 399 | |
| 400 | memalloc_noio_restore(noio_flag); |
| 401 | return ptr; |
| 402 | } |
| 403 | |
| 404 | return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); |
| 405 | } |
| 406 | |
| 407 | /* |
| 408 | * Free buffer's data. |
| 409 | */ |
| 410 | static void free_buffer_data(struct dm_bufio_client *c, |
| 411 | void *data, unsigned char data_mode) |
| 412 | { |
| 413 | switch (data_mode) { |
| 414 | case DATA_MODE_SLAB: |
| 415 | kmem_cache_free(c->slab_cache, data); |
| 416 | break; |
| 417 | |
| 418 | case DATA_MODE_GET_FREE_PAGES: |
| 419 | free_pages((unsigned long)data, c->pages_per_block_bits); |
| 420 | break; |
| 421 | |
| 422 | case DATA_MODE_VMALLOC: |
| 423 | vfree(data); |
| 424 | break; |
| 425 | |
| 426 | default: |
| 427 | DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", |
| 428 | data_mode); |
| 429 | BUG(); |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | /* |
| 434 | * Allocate buffer and its data. |
| 435 | */ |
| 436 | static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) |
| 437 | { |
| 438 | struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size, |
| 439 | gfp_mask); |
| 440 | |
| 441 | if (!b) |
| 442 | return NULL; |
| 443 | |
| 444 | b->c = c; |
| 445 | |
| 446 | b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); |
| 447 | if (!b->data) { |
| 448 | kfree(b); |
| 449 | return NULL; |
| 450 | } |
| 451 | |
| 452 | adjust_total_allocated(b->data_mode, (long)c->block_size); |
| 453 | |
| 454 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 455 | memset(&b->stack_trace, 0, sizeof(b->stack_trace)); |
| 456 | #endif |
| 457 | return b; |
| 458 | } |
| 459 | |
| 460 | /* |
| 461 | * Free buffer and its data. |
| 462 | */ |
| 463 | static void free_buffer(struct dm_buffer *b) |
| 464 | { |
| 465 | struct dm_bufio_client *c = b->c; |
| 466 | |
| 467 | adjust_total_allocated(b->data_mode, -(long)c->block_size); |
| 468 | |
| 469 | free_buffer_data(c, b->data, b->data_mode); |
| 470 | kfree(b); |
| 471 | } |
| 472 | |
| 473 | /* |
| 474 | * Link buffer to the hash list and clean or dirty queue. |
| 475 | */ |
| 476 | static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) |
| 477 | { |
| 478 | struct dm_bufio_client *c = b->c; |
| 479 | |
| 480 | c->n_buffers[dirty]++; |
| 481 | b->block = block; |
| 482 | b->list_mode = dirty; |
| 483 | list_add(&b->lru_list, &c->lru[dirty]); |
| 484 | __insert(b->c, b); |
| 485 | b->last_accessed = jiffies; |
| 486 | } |
| 487 | |
| 488 | /* |
| 489 | * Unlink buffer from the hash list and dirty or clean queue. |
| 490 | */ |
| 491 | static void __unlink_buffer(struct dm_buffer *b) |
| 492 | { |
| 493 | struct dm_bufio_client *c = b->c; |
| 494 | |
| 495 | BUG_ON(!c->n_buffers[b->list_mode]); |
| 496 | |
| 497 | c->n_buffers[b->list_mode]--; |
| 498 | __remove(b->c, b); |
| 499 | list_del(&b->lru_list); |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * Place the buffer to the head of dirty or clean LRU queue. |
| 504 | */ |
| 505 | static void __relink_lru(struct dm_buffer *b, int dirty) |
| 506 | { |
| 507 | struct dm_bufio_client *c = b->c; |
| 508 | |
| 509 | BUG_ON(!c->n_buffers[b->list_mode]); |
| 510 | |
| 511 | c->n_buffers[b->list_mode]--; |
| 512 | c->n_buffers[dirty]++; |
| 513 | b->list_mode = dirty; |
| 514 | list_move(&b->lru_list, &c->lru[dirty]); |
| 515 | b->last_accessed = jiffies; |
| 516 | } |
| 517 | |
| 518 | /*---------------------------------------------------------------- |
| 519 | * Submit I/O on the buffer. |
| 520 | * |
| 521 | * Bio interface is faster but it has some problems: |
| 522 | * the vector list is limited (increasing this limit increases |
| 523 | * memory-consumption per buffer, so it is not viable); |
| 524 | * |
| 525 | * the memory must be direct-mapped, not vmalloced; |
| 526 | * |
| 527 | * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and |
| 528 | * it is not vmalloced, try using the bio interface. |
| 529 | * |
| 530 | * If the buffer is big, if it is vmalloced or if the underlying device |
| 531 | * rejects the bio because it is too large, use dm-io layer to do the I/O. |
| 532 | * The dm-io layer splits the I/O into multiple requests, avoiding the above |
| 533 | * shortcomings. |
| 534 | *--------------------------------------------------------------*/ |
| 535 | |
| 536 | /* |
| 537 | * dm-io completion routine. It just calls b->bio.bi_end_io, pretending |
| 538 | * that the request was handled directly with bio interface. |
| 539 | */ |
| 540 | static void dmio_complete(unsigned long error, void *context) |
| 541 | { |
| 542 | struct dm_buffer *b = context; |
| 543 | |
| 544 | b->bio.bi_status = error ? BLK_STS_IOERR : 0; |
| 545 | b->bio.bi_end_io(&b->bio); |
| 546 | } |
| 547 | |
| 548 | static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, |
| 549 | unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) |
| 550 | { |
| 551 | int r; |
| 552 | struct dm_io_request io_req = { |
| 553 | .bi_op = rw, |
| 554 | .bi_op_flags = 0, |
| 555 | .notify.fn = dmio_complete, |
| 556 | .notify.context = b, |
| 557 | .client = b->c->dm_io, |
| 558 | }; |
| 559 | struct dm_io_region region = { |
| 560 | .bdev = b->c->bdev, |
| 561 | .sector = sector, |
| 562 | .count = n_sectors, |
| 563 | }; |
| 564 | |
| 565 | if (b->data_mode != DATA_MODE_VMALLOC) { |
| 566 | io_req.mem.type = DM_IO_KMEM; |
| 567 | io_req.mem.ptr.addr = (char *)b->data + offset; |
| 568 | } else { |
| 569 | io_req.mem.type = DM_IO_VMA; |
| 570 | io_req.mem.ptr.vma = (char *)b->data + offset; |
| 571 | } |
| 572 | |
| 573 | b->bio.bi_end_io = end_io; |
| 574 | |
| 575 | r = dm_io(&io_req, 1, ®ion, NULL); |
| 576 | if (r) { |
| 577 | b->bio.bi_status = errno_to_blk_status(r); |
| 578 | end_io(&b->bio); |
| 579 | } |
| 580 | } |
| 581 | |
| 582 | static void inline_endio(struct bio *bio) |
| 583 | { |
| 584 | bio_end_io_t *end_fn = bio->bi_private; |
| 585 | blk_status_t status = bio->bi_status; |
| 586 | |
| 587 | /* |
| 588 | * Reset the bio to free any attached resources |
| 589 | * (e.g. bio integrity profiles). |
| 590 | */ |
| 591 | bio_reset(bio); |
| 592 | |
| 593 | bio->bi_status = status; |
| 594 | end_fn(bio); |
| 595 | } |
| 596 | |
| 597 | static void use_inline_bio(struct dm_buffer *b, int rw, sector_t sector, |
| 598 | unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) |
| 599 | { |
| 600 | char *ptr; |
| 601 | unsigned len; |
| 602 | |
| 603 | bio_init(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS); |
| 604 | b->bio.bi_iter.bi_sector = sector; |
| 605 | bio_set_dev(&b->bio, b->c->bdev); |
| 606 | b->bio.bi_end_io = inline_endio; |
| 607 | /* |
| 608 | * Use of .bi_private isn't a problem here because |
| 609 | * the dm_buffer's inline bio is local to bufio. |
| 610 | */ |
| 611 | b->bio.bi_private = end_io; |
| 612 | bio_set_op_attrs(&b->bio, rw, 0); |
| 613 | |
| 614 | ptr = (char *)b->data + offset; |
| 615 | len = n_sectors << SECTOR_SHIFT; |
| 616 | |
| 617 | do { |
| 618 | unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len); |
| 619 | if (!bio_add_page(&b->bio, virt_to_page(ptr), this_step, |
| 620 | offset_in_page(ptr))) { |
| 621 | use_dmio(b, rw, sector, n_sectors, offset, end_io); |
| 622 | return; |
| 623 | } |
| 624 | |
| 625 | len -= this_step; |
| 626 | ptr += this_step; |
| 627 | } while (len > 0); |
| 628 | |
| 629 | submit_bio(&b->bio); |
| 630 | } |
| 631 | |
| 632 | static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io) |
| 633 | { |
| 634 | unsigned n_sectors; |
| 635 | sector_t sector; |
| 636 | unsigned offset, end; |
| 637 | |
| 638 | sector = (b->block << b->c->sectors_per_block_bits) + b->c->start; |
| 639 | |
| 640 | if (rw != REQ_OP_WRITE) { |
| 641 | n_sectors = 1 << b->c->sectors_per_block_bits; |
| 642 | offset = 0; |
| 643 | } else { |
| 644 | if (b->c->write_callback) |
| 645 | b->c->write_callback(b); |
| 646 | offset = b->write_start; |
| 647 | end = b->write_end; |
| 648 | offset &= -DM_BUFIO_WRITE_ALIGN; |
| 649 | end += DM_BUFIO_WRITE_ALIGN - 1; |
| 650 | end &= -DM_BUFIO_WRITE_ALIGN; |
| 651 | if (unlikely(end > b->c->block_size)) |
| 652 | end = b->c->block_size; |
| 653 | |
| 654 | sector += offset >> SECTOR_SHIFT; |
| 655 | n_sectors = (end - offset) >> SECTOR_SHIFT; |
| 656 | } |
| 657 | |
| 658 | if (n_sectors <= ((DM_BUFIO_INLINE_VECS * PAGE_SIZE) >> SECTOR_SHIFT) && |
| 659 | b->data_mode != DATA_MODE_VMALLOC) |
| 660 | use_inline_bio(b, rw, sector, n_sectors, offset, end_io); |
| 661 | else |
| 662 | use_dmio(b, rw, sector, n_sectors, offset, end_io); |
| 663 | } |
| 664 | |
| 665 | /*---------------------------------------------------------------- |
| 666 | * Writing dirty buffers |
| 667 | *--------------------------------------------------------------*/ |
| 668 | |
| 669 | /* |
| 670 | * The endio routine for write. |
| 671 | * |
| 672 | * Set the error, clear B_WRITING bit and wake anyone who was waiting on |
| 673 | * it. |
| 674 | */ |
| 675 | static void write_endio(struct bio *bio) |
| 676 | { |
| 677 | struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); |
| 678 | |
| 679 | b->write_error = bio->bi_status; |
| 680 | if (unlikely(bio->bi_status)) { |
| 681 | struct dm_bufio_client *c = b->c; |
| 682 | |
| 683 | (void)cmpxchg(&c->async_write_error, 0, |
| 684 | blk_status_to_errno(bio->bi_status)); |
| 685 | } |
| 686 | |
| 687 | BUG_ON(!test_bit(B_WRITING, &b->state)); |
| 688 | |
| 689 | smp_mb__before_atomic(); |
| 690 | clear_bit(B_WRITING, &b->state); |
| 691 | smp_mb__after_atomic(); |
| 692 | |
| 693 | wake_up_bit(&b->state, B_WRITING); |
| 694 | } |
| 695 | |
| 696 | /* |
| 697 | * Initiate a write on a dirty buffer, but don't wait for it. |
| 698 | * |
| 699 | * - If the buffer is not dirty, exit. |
| 700 | * - If there some previous write going on, wait for it to finish (we can't |
| 701 | * have two writes on the same buffer simultaneously). |
| 702 | * - Submit our write and don't wait on it. We set B_WRITING indicating |
| 703 | * that there is a write in progress. |
| 704 | */ |
| 705 | static void __write_dirty_buffer(struct dm_buffer *b, |
| 706 | struct list_head *write_list) |
| 707 | { |
| 708 | if (!test_bit(B_DIRTY, &b->state)) |
| 709 | return; |
| 710 | |
| 711 | clear_bit(B_DIRTY, &b->state); |
| 712 | wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); |
| 713 | |
| 714 | b->write_start = b->dirty_start; |
| 715 | b->write_end = b->dirty_end; |
| 716 | |
| 717 | if (!write_list) |
| 718 | submit_io(b, REQ_OP_WRITE, write_endio); |
| 719 | else |
| 720 | list_add_tail(&b->write_list, write_list); |
| 721 | } |
| 722 | |
| 723 | static void __flush_write_list(struct list_head *write_list) |
| 724 | { |
| 725 | struct blk_plug plug; |
| 726 | blk_start_plug(&plug); |
| 727 | while (!list_empty(write_list)) { |
| 728 | struct dm_buffer *b = |
| 729 | list_entry(write_list->next, struct dm_buffer, write_list); |
| 730 | list_del(&b->write_list); |
| 731 | submit_io(b, REQ_OP_WRITE, write_endio); |
| 732 | cond_resched(); |
| 733 | } |
| 734 | blk_finish_plug(&plug); |
| 735 | } |
| 736 | |
| 737 | /* |
| 738 | * Wait until any activity on the buffer finishes. Possibly write the |
| 739 | * buffer if it is dirty. When this function finishes, there is no I/O |
| 740 | * running on the buffer and the buffer is not dirty. |
| 741 | */ |
| 742 | static void __make_buffer_clean(struct dm_buffer *b) |
| 743 | { |
| 744 | BUG_ON(b->hold_count); |
| 745 | |
| 746 | if (!b->state) /* fast case */ |
| 747 | return; |
| 748 | |
| 749 | wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); |
| 750 | __write_dirty_buffer(b, NULL); |
| 751 | wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); |
| 752 | } |
| 753 | |
| 754 | /* |
| 755 | * Find some buffer that is not held by anybody, clean it, unlink it and |
| 756 | * return it. |
| 757 | */ |
| 758 | static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) |
| 759 | { |
| 760 | struct dm_buffer *b; |
| 761 | |
| 762 | list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { |
| 763 | BUG_ON(test_bit(B_WRITING, &b->state)); |
| 764 | BUG_ON(test_bit(B_DIRTY, &b->state)); |
| 765 | |
| 766 | if (!b->hold_count) { |
| 767 | __make_buffer_clean(b); |
| 768 | __unlink_buffer(b); |
| 769 | return b; |
| 770 | } |
| 771 | cond_resched(); |
| 772 | } |
| 773 | |
| 774 | list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { |
| 775 | BUG_ON(test_bit(B_READING, &b->state)); |
| 776 | |
| 777 | if (!b->hold_count) { |
| 778 | __make_buffer_clean(b); |
| 779 | __unlink_buffer(b); |
| 780 | return b; |
| 781 | } |
| 782 | cond_resched(); |
| 783 | } |
| 784 | |
| 785 | return NULL; |
| 786 | } |
| 787 | |
| 788 | /* |
| 789 | * Wait until some other threads free some buffer or release hold count on |
| 790 | * some buffer. |
| 791 | * |
| 792 | * This function is entered with c->lock held, drops it and regains it |
| 793 | * before exiting. |
| 794 | */ |
| 795 | static void __wait_for_free_buffer(struct dm_bufio_client *c) |
| 796 | { |
| 797 | DECLARE_WAITQUEUE(wait, current); |
| 798 | |
| 799 | add_wait_queue(&c->free_buffer_wait, &wait); |
| 800 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 801 | dm_bufio_unlock(c); |
| 802 | |
| 803 | io_schedule(); |
| 804 | |
| 805 | remove_wait_queue(&c->free_buffer_wait, &wait); |
| 806 | |
| 807 | dm_bufio_lock(c); |
| 808 | } |
| 809 | |
| 810 | enum new_flag { |
| 811 | NF_FRESH = 0, |
| 812 | NF_READ = 1, |
| 813 | NF_GET = 2, |
| 814 | NF_PREFETCH = 3 |
| 815 | }; |
| 816 | |
| 817 | /* |
| 818 | * Allocate a new buffer. If the allocation is not possible, wait until |
| 819 | * some other thread frees a buffer. |
| 820 | * |
| 821 | * May drop the lock and regain it. |
| 822 | */ |
| 823 | static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) |
| 824 | { |
| 825 | struct dm_buffer *b; |
| 826 | bool tried_noio_alloc = false; |
| 827 | |
| 828 | /* |
| 829 | * dm-bufio is resistant to allocation failures (it just keeps |
| 830 | * one buffer reserved in cases all the allocations fail). |
| 831 | * So set flags to not try too hard: |
| 832 | * GFP_NOWAIT: don't wait; if we need to sleep we'll release our |
| 833 | * mutex and wait ourselves. |
| 834 | * __GFP_NORETRY: don't retry and rather return failure |
| 835 | * __GFP_NOMEMALLOC: don't use emergency reserves |
| 836 | * __GFP_NOWARN: don't print a warning in case of failure |
| 837 | * |
| 838 | * For debugging, if we set the cache size to 1, no new buffers will |
| 839 | * be allocated. |
| 840 | */ |
| 841 | while (1) { |
| 842 | if (dm_bufio_cache_size_latch != 1) { |
| 843 | b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| 844 | if (b) |
| 845 | return b; |
| 846 | } |
| 847 | |
| 848 | if (nf == NF_PREFETCH) |
| 849 | return NULL; |
| 850 | |
| 851 | if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { |
| 852 | dm_bufio_unlock(c); |
| 853 | b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| 854 | dm_bufio_lock(c); |
| 855 | if (b) |
| 856 | return b; |
| 857 | tried_noio_alloc = true; |
| 858 | } |
| 859 | |
| 860 | if (!list_empty(&c->reserved_buffers)) { |
| 861 | b = list_entry(c->reserved_buffers.next, |
| 862 | struct dm_buffer, lru_list); |
| 863 | list_del(&b->lru_list); |
| 864 | c->need_reserved_buffers++; |
| 865 | |
| 866 | return b; |
| 867 | } |
| 868 | |
| 869 | b = __get_unclaimed_buffer(c); |
| 870 | if (b) |
| 871 | return b; |
| 872 | |
| 873 | __wait_for_free_buffer(c); |
| 874 | } |
| 875 | } |
| 876 | |
| 877 | static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) |
| 878 | { |
| 879 | struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); |
| 880 | |
| 881 | if (!b) |
| 882 | return NULL; |
| 883 | |
| 884 | if (c->alloc_callback) |
| 885 | c->alloc_callback(b); |
| 886 | |
| 887 | return b; |
| 888 | } |
| 889 | |
| 890 | /* |
| 891 | * Free a buffer and wake other threads waiting for free buffers. |
| 892 | */ |
| 893 | static void __free_buffer_wake(struct dm_buffer *b) |
| 894 | { |
| 895 | struct dm_bufio_client *c = b->c; |
| 896 | |
| 897 | if (!c->need_reserved_buffers) |
| 898 | free_buffer(b); |
| 899 | else { |
| 900 | list_add(&b->lru_list, &c->reserved_buffers); |
| 901 | c->need_reserved_buffers--; |
| 902 | } |
| 903 | |
| 904 | wake_up(&c->free_buffer_wait); |
| 905 | } |
| 906 | |
| 907 | static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, |
| 908 | struct list_head *write_list) |
| 909 | { |
| 910 | struct dm_buffer *b, *tmp; |
| 911 | |
| 912 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { |
| 913 | BUG_ON(test_bit(B_READING, &b->state)); |
| 914 | |
| 915 | if (!test_bit(B_DIRTY, &b->state) && |
| 916 | !test_bit(B_WRITING, &b->state)) { |
| 917 | __relink_lru(b, LIST_CLEAN); |
| 918 | continue; |
| 919 | } |
| 920 | |
| 921 | if (no_wait && test_bit(B_WRITING, &b->state)) |
| 922 | return; |
| 923 | |
| 924 | __write_dirty_buffer(b, write_list); |
| 925 | cond_resched(); |
| 926 | } |
| 927 | } |
| 928 | |
| 929 | /* |
| 930 | * Get writeback threshold and buffer limit for a given client. |
| 931 | */ |
| 932 | static void __get_memory_limit(struct dm_bufio_client *c, |
| 933 | unsigned long *threshold_buffers, |
| 934 | unsigned long *limit_buffers) |
| 935 | { |
| 936 | unsigned long buffers; |
| 937 | |
| 938 | if (unlikely(READ_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch)) { |
| 939 | if (mutex_trylock(&dm_bufio_clients_lock)) { |
| 940 | __cache_size_refresh(); |
| 941 | mutex_unlock(&dm_bufio_clients_lock); |
| 942 | } |
| 943 | } |
| 944 | |
| 945 | buffers = dm_bufio_cache_size_per_client >> |
| 946 | (c->sectors_per_block_bits + SECTOR_SHIFT); |
| 947 | |
| 948 | if (buffers < c->minimum_buffers) |
| 949 | buffers = c->minimum_buffers; |
| 950 | |
| 951 | *limit_buffers = buffers; |
| 952 | *threshold_buffers = mult_frac(buffers, |
| 953 | DM_BUFIO_WRITEBACK_PERCENT, 100); |
| 954 | } |
| 955 | |
| 956 | /* |
| 957 | * Check if we're over watermark. |
| 958 | * If we are over threshold_buffers, start freeing buffers. |
| 959 | * If we're over "limit_buffers", block until we get under the limit. |
| 960 | */ |
| 961 | static void __check_watermark(struct dm_bufio_client *c, |
| 962 | struct list_head *write_list) |
| 963 | { |
| 964 | unsigned long threshold_buffers, limit_buffers; |
| 965 | |
| 966 | __get_memory_limit(c, &threshold_buffers, &limit_buffers); |
| 967 | |
| 968 | while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > |
| 969 | limit_buffers) { |
| 970 | |
| 971 | struct dm_buffer *b = __get_unclaimed_buffer(c); |
| 972 | |
| 973 | if (!b) |
| 974 | return; |
| 975 | |
| 976 | __free_buffer_wake(b); |
| 977 | cond_resched(); |
| 978 | } |
| 979 | |
| 980 | if (c->n_buffers[LIST_DIRTY] > threshold_buffers) |
| 981 | __write_dirty_buffers_async(c, 1, write_list); |
| 982 | } |
| 983 | |
| 984 | /*---------------------------------------------------------------- |
| 985 | * Getting a buffer |
| 986 | *--------------------------------------------------------------*/ |
| 987 | |
| 988 | static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, |
| 989 | enum new_flag nf, int *need_submit, |
| 990 | struct list_head *write_list) |
| 991 | { |
| 992 | struct dm_buffer *b, *new_b = NULL; |
| 993 | |
| 994 | *need_submit = 0; |
| 995 | |
| 996 | b = __find(c, block); |
| 997 | if (b) |
| 998 | goto found_buffer; |
| 999 | |
| 1000 | if (nf == NF_GET) |
| 1001 | return NULL; |
| 1002 | |
| 1003 | new_b = __alloc_buffer_wait(c, nf); |
| 1004 | if (!new_b) |
| 1005 | return NULL; |
| 1006 | |
| 1007 | /* |
| 1008 | * We've had a period where the mutex was unlocked, so need to |
| 1009 | * recheck the hash table. |
| 1010 | */ |
| 1011 | b = __find(c, block); |
| 1012 | if (b) { |
| 1013 | __free_buffer_wake(new_b); |
| 1014 | goto found_buffer; |
| 1015 | } |
| 1016 | |
| 1017 | __check_watermark(c, write_list); |
| 1018 | |
| 1019 | b = new_b; |
| 1020 | b->hold_count = 1; |
| 1021 | b->read_error = 0; |
| 1022 | b->write_error = 0; |
| 1023 | __link_buffer(b, block, LIST_CLEAN); |
| 1024 | |
| 1025 | if (nf == NF_FRESH) { |
| 1026 | b->state = 0; |
| 1027 | return b; |
| 1028 | } |
| 1029 | |
| 1030 | b->state = 1 << B_READING; |
| 1031 | *need_submit = 1; |
| 1032 | |
| 1033 | return b; |
| 1034 | |
| 1035 | found_buffer: |
| 1036 | if (nf == NF_PREFETCH) |
| 1037 | return NULL; |
| 1038 | /* |
| 1039 | * Note: it is essential that we don't wait for the buffer to be |
| 1040 | * read if dm_bufio_get function is used. Both dm_bufio_get and |
| 1041 | * dm_bufio_prefetch can be used in the driver request routine. |
| 1042 | * If the user called both dm_bufio_prefetch and dm_bufio_get on |
| 1043 | * the same buffer, it would deadlock if we waited. |
| 1044 | */ |
| 1045 | if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) |
| 1046 | return NULL; |
| 1047 | |
| 1048 | b->hold_count++; |
| 1049 | __relink_lru(b, test_bit(B_DIRTY, &b->state) || |
| 1050 | test_bit(B_WRITING, &b->state)); |
| 1051 | return b; |
| 1052 | } |
| 1053 | |
| 1054 | /* |
| 1055 | * The endio routine for reading: set the error, clear the bit and wake up |
| 1056 | * anyone waiting on the buffer. |
| 1057 | */ |
| 1058 | static void read_endio(struct bio *bio) |
| 1059 | { |
| 1060 | struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); |
| 1061 | |
| 1062 | b->read_error = bio->bi_status; |
| 1063 | |
| 1064 | BUG_ON(!test_bit(B_READING, &b->state)); |
| 1065 | |
| 1066 | smp_mb__before_atomic(); |
| 1067 | clear_bit(B_READING, &b->state); |
| 1068 | smp_mb__after_atomic(); |
| 1069 | |
| 1070 | wake_up_bit(&b->state, B_READING); |
| 1071 | } |
| 1072 | |
| 1073 | /* |
| 1074 | * A common routine for dm_bufio_new and dm_bufio_read. Operation of these |
| 1075 | * functions is similar except that dm_bufio_new doesn't read the |
| 1076 | * buffer from the disk (assuming that the caller overwrites all the data |
| 1077 | * and uses dm_bufio_mark_buffer_dirty to write new data back). |
| 1078 | */ |
| 1079 | static void *new_read(struct dm_bufio_client *c, sector_t block, |
| 1080 | enum new_flag nf, struct dm_buffer **bp) |
| 1081 | { |
| 1082 | int need_submit; |
| 1083 | struct dm_buffer *b; |
| 1084 | |
| 1085 | LIST_HEAD(write_list); |
| 1086 | |
| 1087 | dm_bufio_lock(c); |
| 1088 | b = __bufio_new(c, block, nf, &need_submit, &write_list); |
| 1089 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 1090 | if (b && b->hold_count == 1) |
| 1091 | buffer_record_stack(b); |
| 1092 | #endif |
| 1093 | dm_bufio_unlock(c); |
| 1094 | |
| 1095 | __flush_write_list(&write_list); |
| 1096 | |
| 1097 | if (!b) |
| 1098 | return NULL; |
| 1099 | |
| 1100 | if (need_submit) |
| 1101 | submit_io(b, REQ_OP_READ, read_endio); |
| 1102 | |
| 1103 | wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); |
| 1104 | |
| 1105 | if (b->read_error) { |
| 1106 | int error = blk_status_to_errno(b->read_error); |
| 1107 | |
| 1108 | dm_bufio_release(b); |
| 1109 | |
| 1110 | return ERR_PTR(error); |
| 1111 | } |
| 1112 | |
| 1113 | *bp = b; |
| 1114 | |
| 1115 | return b->data; |
| 1116 | } |
| 1117 | |
| 1118 | void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, |
| 1119 | struct dm_buffer **bp) |
| 1120 | { |
| 1121 | return new_read(c, block, NF_GET, bp); |
| 1122 | } |
| 1123 | EXPORT_SYMBOL_GPL(dm_bufio_get); |
| 1124 | |
| 1125 | void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, |
| 1126 | struct dm_buffer **bp) |
| 1127 | { |
| 1128 | BUG_ON(dm_bufio_in_request()); |
| 1129 | |
| 1130 | return new_read(c, block, NF_READ, bp); |
| 1131 | } |
| 1132 | EXPORT_SYMBOL_GPL(dm_bufio_read); |
| 1133 | |
| 1134 | void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, |
| 1135 | struct dm_buffer **bp) |
| 1136 | { |
| 1137 | BUG_ON(dm_bufio_in_request()); |
| 1138 | |
| 1139 | return new_read(c, block, NF_FRESH, bp); |
| 1140 | } |
| 1141 | EXPORT_SYMBOL_GPL(dm_bufio_new); |
| 1142 | |
| 1143 | void dm_bufio_prefetch(struct dm_bufio_client *c, |
| 1144 | sector_t block, unsigned n_blocks) |
| 1145 | { |
| 1146 | struct blk_plug plug; |
| 1147 | |
| 1148 | LIST_HEAD(write_list); |
| 1149 | |
| 1150 | BUG_ON(dm_bufio_in_request()); |
| 1151 | |
| 1152 | blk_start_plug(&plug); |
| 1153 | dm_bufio_lock(c); |
| 1154 | |
| 1155 | for (; n_blocks--; block++) { |
| 1156 | int need_submit; |
| 1157 | struct dm_buffer *b; |
| 1158 | b = __bufio_new(c, block, NF_PREFETCH, &need_submit, |
| 1159 | &write_list); |
| 1160 | if (unlikely(!list_empty(&write_list))) { |
| 1161 | dm_bufio_unlock(c); |
| 1162 | blk_finish_plug(&plug); |
| 1163 | __flush_write_list(&write_list); |
| 1164 | blk_start_plug(&plug); |
| 1165 | dm_bufio_lock(c); |
| 1166 | } |
| 1167 | if (unlikely(b != NULL)) { |
| 1168 | dm_bufio_unlock(c); |
| 1169 | |
| 1170 | if (need_submit) |
| 1171 | submit_io(b, REQ_OP_READ, read_endio); |
| 1172 | dm_bufio_release(b); |
| 1173 | |
| 1174 | cond_resched(); |
| 1175 | |
| 1176 | if (!n_blocks) |
| 1177 | goto flush_plug; |
| 1178 | dm_bufio_lock(c); |
| 1179 | } |
| 1180 | } |
| 1181 | |
| 1182 | dm_bufio_unlock(c); |
| 1183 | |
| 1184 | flush_plug: |
| 1185 | blk_finish_plug(&plug); |
| 1186 | } |
| 1187 | EXPORT_SYMBOL_GPL(dm_bufio_prefetch); |
| 1188 | |
| 1189 | void dm_bufio_release(struct dm_buffer *b) |
| 1190 | { |
| 1191 | struct dm_bufio_client *c = b->c; |
| 1192 | |
| 1193 | dm_bufio_lock(c); |
| 1194 | |
| 1195 | BUG_ON(!b->hold_count); |
| 1196 | |
| 1197 | b->hold_count--; |
| 1198 | if (!b->hold_count) { |
| 1199 | wake_up(&c->free_buffer_wait); |
| 1200 | |
| 1201 | /* |
| 1202 | * If there were errors on the buffer, and the buffer is not |
| 1203 | * to be written, free the buffer. There is no point in caching |
| 1204 | * invalid buffer. |
| 1205 | */ |
| 1206 | if ((b->read_error || b->write_error) && |
| 1207 | !test_bit(B_READING, &b->state) && |
| 1208 | !test_bit(B_WRITING, &b->state) && |
| 1209 | !test_bit(B_DIRTY, &b->state)) { |
| 1210 | __unlink_buffer(b); |
| 1211 | __free_buffer_wake(b); |
| 1212 | } |
| 1213 | } |
| 1214 | |
| 1215 | dm_bufio_unlock(c); |
| 1216 | } |
| 1217 | EXPORT_SYMBOL_GPL(dm_bufio_release); |
| 1218 | |
| 1219 | void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, |
| 1220 | unsigned start, unsigned end) |
| 1221 | { |
| 1222 | struct dm_bufio_client *c = b->c; |
| 1223 | |
| 1224 | BUG_ON(start >= end); |
| 1225 | BUG_ON(end > b->c->block_size); |
| 1226 | |
| 1227 | dm_bufio_lock(c); |
| 1228 | |
| 1229 | BUG_ON(test_bit(B_READING, &b->state)); |
| 1230 | |
| 1231 | if (!test_and_set_bit(B_DIRTY, &b->state)) { |
| 1232 | b->dirty_start = start; |
| 1233 | b->dirty_end = end; |
| 1234 | __relink_lru(b, LIST_DIRTY); |
| 1235 | } else { |
| 1236 | if (start < b->dirty_start) |
| 1237 | b->dirty_start = start; |
| 1238 | if (end > b->dirty_end) |
| 1239 | b->dirty_end = end; |
| 1240 | } |
| 1241 | |
| 1242 | dm_bufio_unlock(c); |
| 1243 | } |
| 1244 | EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty); |
| 1245 | |
| 1246 | void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) |
| 1247 | { |
| 1248 | dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); |
| 1249 | } |
| 1250 | EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); |
| 1251 | |
| 1252 | void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) |
| 1253 | { |
| 1254 | LIST_HEAD(write_list); |
| 1255 | |
| 1256 | BUG_ON(dm_bufio_in_request()); |
| 1257 | |
| 1258 | dm_bufio_lock(c); |
| 1259 | __write_dirty_buffers_async(c, 0, &write_list); |
| 1260 | dm_bufio_unlock(c); |
| 1261 | __flush_write_list(&write_list); |
| 1262 | } |
| 1263 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); |
| 1264 | |
| 1265 | /* |
| 1266 | * For performance, it is essential that the buffers are written asynchronously |
| 1267 | * and simultaneously (so that the block layer can merge the writes) and then |
| 1268 | * waited upon. |
| 1269 | * |
| 1270 | * Finally, we flush hardware disk cache. |
| 1271 | */ |
| 1272 | int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) |
| 1273 | { |
| 1274 | int a, f; |
| 1275 | unsigned long buffers_processed = 0; |
| 1276 | struct dm_buffer *b, *tmp; |
| 1277 | |
| 1278 | LIST_HEAD(write_list); |
| 1279 | |
| 1280 | dm_bufio_lock(c); |
| 1281 | __write_dirty_buffers_async(c, 0, &write_list); |
| 1282 | dm_bufio_unlock(c); |
| 1283 | __flush_write_list(&write_list); |
| 1284 | dm_bufio_lock(c); |
| 1285 | |
| 1286 | again: |
| 1287 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { |
| 1288 | int dropped_lock = 0; |
| 1289 | |
| 1290 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) |
| 1291 | buffers_processed++; |
| 1292 | |
| 1293 | BUG_ON(test_bit(B_READING, &b->state)); |
| 1294 | |
| 1295 | if (test_bit(B_WRITING, &b->state)) { |
| 1296 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) { |
| 1297 | dropped_lock = 1; |
| 1298 | b->hold_count++; |
| 1299 | dm_bufio_unlock(c); |
| 1300 | wait_on_bit_io(&b->state, B_WRITING, |
| 1301 | TASK_UNINTERRUPTIBLE); |
| 1302 | dm_bufio_lock(c); |
| 1303 | b->hold_count--; |
| 1304 | } else |
| 1305 | wait_on_bit_io(&b->state, B_WRITING, |
| 1306 | TASK_UNINTERRUPTIBLE); |
| 1307 | } |
| 1308 | |
| 1309 | if (!test_bit(B_DIRTY, &b->state) && |
| 1310 | !test_bit(B_WRITING, &b->state)) |
| 1311 | __relink_lru(b, LIST_CLEAN); |
| 1312 | |
| 1313 | cond_resched(); |
| 1314 | |
| 1315 | /* |
| 1316 | * If we dropped the lock, the list is no longer consistent, |
| 1317 | * so we must restart the search. |
| 1318 | * |
| 1319 | * In the most common case, the buffer just processed is |
| 1320 | * relinked to the clean list, so we won't loop scanning the |
| 1321 | * same buffer again and again. |
| 1322 | * |
| 1323 | * This may livelock if there is another thread simultaneously |
| 1324 | * dirtying buffers, so we count the number of buffers walked |
| 1325 | * and if it exceeds the total number of buffers, it means that |
| 1326 | * someone is doing some writes simultaneously with us. In |
| 1327 | * this case, stop, dropping the lock. |
| 1328 | */ |
| 1329 | if (dropped_lock) |
| 1330 | goto again; |
| 1331 | } |
| 1332 | wake_up(&c->free_buffer_wait); |
| 1333 | dm_bufio_unlock(c); |
| 1334 | |
| 1335 | a = xchg(&c->async_write_error, 0); |
| 1336 | f = dm_bufio_issue_flush(c); |
| 1337 | if (a) |
| 1338 | return a; |
| 1339 | |
| 1340 | return f; |
| 1341 | } |
| 1342 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); |
| 1343 | |
| 1344 | /* |
| 1345 | * Use dm-io to send and empty barrier flush the device. |
| 1346 | */ |
| 1347 | int dm_bufio_issue_flush(struct dm_bufio_client *c) |
| 1348 | { |
| 1349 | struct dm_io_request io_req = { |
| 1350 | .bi_op = REQ_OP_WRITE, |
| 1351 | .bi_op_flags = REQ_PREFLUSH | REQ_SYNC, |
| 1352 | .mem.type = DM_IO_KMEM, |
| 1353 | .mem.ptr.addr = NULL, |
| 1354 | .client = c->dm_io, |
| 1355 | }; |
| 1356 | struct dm_io_region io_reg = { |
| 1357 | .bdev = c->bdev, |
| 1358 | .sector = 0, |
| 1359 | .count = 0, |
| 1360 | }; |
| 1361 | |
| 1362 | BUG_ON(dm_bufio_in_request()); |
| 1363 | |
| 1364 | return dm_io(&io_req, 1, &io_reg, NULL); |
| 1365 | } |
| 1366 | EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); |
| 1367 | |
| 1368 | /* |
| 1369 | * We first delete any other buffer that may be at that new location. |
| 1370 | * |
| 1371 | * Then, we write the buffer to the original location if it was dirty. |
| 1372 | * |
| 1373 | * Then, if we are the only one who is holding the buffer, relink the buffer |
| 1374 | * in the hash queue for the new location. |
| 1375 | * |
| 1376 | * If there was someone else holding the buffer, we write it to the new |
| 1377 | * location but not relink it, because that other user needs to have the buffer |
| 1378 | * at the same place. |
| 1379 | */ |
| 1380 | void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) |
| 1381 | { |
| 1382 | struct dm_bufio_client *c = b->c; |
| 1383 | struct dm_buffer *new; |
| 1384 | |
| 1385 | BUG_ON(dm_bufio_in_request()); |
| 1386 | |
| 1387 | dm_bufio_lock(c); |
| 1388 | |
| 1389 | retry: |
| 1390 | new = __find(c, new_block); |
| 1391 | if (new) { |
| 1392 | if (new->hold_count) { |
| 1393 | __wait_for_free_buffer(c); |
| 1394 | goto retry; |
| 1395 | } |
| 1396 | |
| 1397 | /* |
| 1398 | * FIXME: Is there any point waiting for a write that's going |
| 1399 | * to be overwritten in a bit? |
| 1400 | */ |
| 1401 | __make_buffer_clean(new); |
| 1402 | __unlink_buffer(new); |
| 1403 | __free_buffer_wake(new); |
| 1404 | } |
| 1405 | |
| 1406 | BUG_ON(!b->hold_count); |
| 1407 | BUG_ON(test_bit(B_READING, &b->state)); |
| 1408 | |
| 1409 | __write_dirty_buffer(b, NULL); |
| 1410 | if (b->hold_count == 1) { |
| 1411 | wait_on_bit_io(&b->state, B_WRITING, |
| 1412 | TASK_UNINTERRUPTIBLE); |
| 1413 | set_bit(B_DIRTY, &b->state); |
| 1414 | b->dirty_start = 0; |
| 1415 | b->dirty_end = c->block_size; |
| 1416 | __unlink_buffer(b); |
| 1417 | __link_buffer(b, new_block, LIST_DIRTY); |
| 1418 | } else { |
| 1419 | sector_t old_block; |
| 1420 | wait_on_bit_lock_io(&b->state, B_WRITING, |
| 1421 | TASK_UNINTERRUPTIBLE); |
| 1422 | /* |
| 1423 | * Relink buffer to "new_block" so that write_callback |
| 1424 | * sees "new_block" as a block number. |
| 1425 | * After the write, link the buffer back to old_block. |
| 1426 | * All this must be done in bufio lock, so that block number |
| 1427 | * change isn't visible to other threads. |
| 1428 | */ |
| 1429 | old_block = b->block; |
| 1430 | __unlink_buffer(b); |
| 1431 | __link_buffer(b, new_block, b->list_mode); |
| 1432 | submit_io(b, REQ_OP_WRITE, write_endio); |
| 1433 | wait_on_bit_io(&b->state, B_WRITING, |
| 1434 | TASK_UNINTERRUPTIBLE); |
| 1435 | __unlink_buffer(b); |
| 1436 | __link_buffer(b, old_block, b->list_mode); |
| 1437 | } |
| 1438 | |
| 1439 | dm_bufio_unlock(c); |
| 1440 | dm_bufio_release(b); |
| 1441 | } |
| 1442 | EXPORT_SYMBOL_GPL(dm_bufio_release_move); |
| 1443 | |
| 1444 | /* |
| 1445 | * Free the given buffer. |
| 1446 | * |
| 1447 | * This is just a hint, if the buffer is in use or dirty, this function |
| 1448 | * does nothing. |
| 1449 | */ |
| 1450 | void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) |
| 1451 | { |
| 1452 | struct dm_buffer *b; |
| 1453 | |
| 1454 | dm_bufio_lock(c); |
| 1455 | |
| 1456 | b = __find(c, block); |
| 1457 | if (b && likely(!b->hold_count) && likely(!b->state)) { |
| 1458 | __unlink_buffer(b); |
| 1459 | __free_buffer_wake(b); |
| 1460 | } |
| 1461 | |
| 1462 | dm_bufio_unlock(c); |
| 1463 | } |
| 1464 | EXPORT_SYMBOL_GPL(dm_bufio_forget); |
| 1465 | |
| 1466 | void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n) |
| 1467 | { |
| 1468 | c->minimum_buffers = n; |
| 1469 | } |
| 1470 | EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers); |
| 1471 | |
| 1472 | unsigned dm_bufio_get_block_size(struct dm_bufio_client *c) |
| 1473 | { |
| 1474 | return c->block_size; |
| 1475 | } |
| 1476 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_size); |
| 1477 | |
| 1478 | sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) |
| 1479 | { |
| 1480 | return i_size_read(c->bdev->bd_inode) >> |
| 1481 | (SECTOR_SHIFT + c->sectors_per_block_bits); |
| 1482 | } |
| 1483 | EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); |
| 1484 | |
| 1485 | sector_t dm_bufio_get_block_number(struct dm_buffer *b) |
| 1486 | { |
| 1487 | return b->block; |
| 1488 | } |
| 1489 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_number); |
| 1490 | |
| 1491 | void *dm_bufio_get_block_data(struct dm_buffer *b) |
| 1492 | { |
| 1493 | return b->data; |
| 1494 | } |
| 1495 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_data); |
| 1496 | |
| 1497 | void *dm_bufio_get_aux_data(struct dm_buffer *b) |
| 1498 | { |
| 1499 | return b + 1; |
| 1500 | } |
| 1501 | EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data); |
| 1502 | |
| 1503 | struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) |
| 1504 | { |
| 1505 | return b->c; |
| 1506 | } |
| 1507 | EXPORT_SYMBOL_GPL(dm_bufio_get_client); |
| 1508 | |
| 1509 | static void drop_buffers(struct dm_bufio_client *c) |
| 1510 | { |
| 1511 | struct dm_buffer *b; |
| 1512 | int i; |
| 1513 | bool warned = false; |
| 1514 | |
| 1515 | BUG_ON(dm_bufio_in_request()); |
| 1516 | |
| 1517 | /* |
| 1518 | * An optimization so that the buffers are not written one-by-one. |
| 1519 | */ |
| 1520 | dm_bufio_write_dirty_buffers_async(c); |
| 1521 | |
| 1522 | dm_bufio_lock(c); |
| 1523 | |
| 1524 | while ((b = __get_unclaimed_buffer(c))) |
| 1525 | __free_buffer_wake(b); |
| 1526 | |
| 1527 | for (i = 0; i < LIST_SIZE; i++) |
| 1528 | list_for_each_entry(b, &c->lru[i], lru_list) { |
| 1529 | WARN_ON(!warned); |
| 1530 | warned = true; |
| 1531 | DMERR("leaked buffer %llx, hold count %u, list %d", |
| 1532 | (unsigned long long)b->block, b->hold_count, i); |
| 1533 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 1534 | print_stack_trace(&b->stack_trace, 1); |
| 1535 | b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */ |
| 1536 | #endif |
| 1537 | } |
| 1538 | |
| 1539 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| 1540 | while ((b = __get_unclaimed_buffer(c))) |
| 1541 | __free_buffer_wake(b); |
| 1542 | #endif |
| 1543 | |
| 1544 | for (i = 0; i < LIST_SIZE; i++) |
| 1545 | BUG_ON(!list_empty(&c->lru[i])); |
| 1546 | |
| 1547 | dm_bufio_unlock(c); |
| 1548 | } |
| 1549 | |
| 1550 | /* |
| 1551 | * We may not be able to evict this buffer if IO pending or the client |
| 1552 | * is still using it. Caller is expected to know buffer is too old. |
| 1553 | * |
| 1554 | * And if GFP_NOFS is used, we must not do any I/O because we hold |
| 1555 | * dm_bufio_clients_lock and we would risk deadlock if the I/O gets |
| 1556 | * rerouted to different bufio client. |
| 1557 | */ |
| 1558 | static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) |
| 1559 | { |
| 1560 | if (!(gfp & __GFP_FS)) { |
| 1561 | if (test_bit(B_READING, &b->state) || |
| 1562 | test_bit(B_WRITING, &b->state) || |
| 1563 | test_bit(B_DIRTY, &b->state)) |
| 1564 | return false; |
| 1565 | } |
| 1566 | |
| 1567 | if (b->hold_count) |
| 1568 | return false; |
| 1569 | |
| 1570 | __make_buffer_clean(b); |
| 1571 | __unlink_buffer(b); |
| 1572 | __free_buffer_wake(b); |
| 1573 | |
| 1574 | return true; |
| 1575 | } |
| 1576 | |
| 1577 | static unsigned long get_retain_buffers(struct dm_bufio_client *c) |
| 1578 | { |
| 1579 | unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes); |
| 1580 | return retain_bytes >> (c->sectors_per_block_bits + SECTOR_SHIFT); |
| 1581 | } |
| 1582 | |
| 1583 | static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, |
| 1584 | gfp_t gfp_mask) |
| 1585 | { |
| 1586 | int l; |
| 1587 | struct dm_buffer *b, *tmp; |
| 1588 | unsigned long freed = 0; |
| 1589 | unsigned long count = c->n_buffers[LIST_CLEAN] + |
| 1590 | c->n_buffers[LIST_DIRTY]; |
| 1591 | unsigned long retain_target = get_retain_buffers(c); |
| 1592 | |
| 1593 | for (l = 0; l < LIST_SIZE; l++) { |
| 1594 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { |
| 1595 | if (__try_evict_buffer(b, gfp_mask)) |
| 1596 | freed++; |
| 1597 | if (!--nr_to_scan || ((count - freed) <= retain_target)) |
| 1598 | return freed; |
| 1599 | cond_resched(); |
| 1600 | } |
| 1601 | } |
| 1602 | return freed; |
| 1603 | } |
| 1604 | |
| 1605 | static unsigned long |
| 1606 | dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) |
| 1607 | { |
| 1608 | struct dm_bufio_client *c; |
| 1609 | unsigned long freed; |
| 1610 | |
| 1611 | c = container_of(shrink, struct dm_bufio_client, shrinker); |
| 1612 | if (sc->gfp_mask & __GFP_FS) |
| 1613 | dm_bufio_lock(c); |
| 1614 | else if (!dm_bufio_trylock(c)) |
| 1615 | return SHRINK_STOP; |
| 1616 | |
| 1617 | freed = __scan(c, sc->nr_to_scan, sc->gfp_mask); |
| 1618 | dm_bufio_unlock(c); |
| 1619 | return freed; |
| 1620 | } |
| 1621 | |
| 1622 | static unsigned long |
| 1623 | dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) |
| 1624 | { |
| 1625 | struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker); |
| 1626 | unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) + |
| 1627 | READ_ONCE(c->n_buffers[LIST_DIRTY]); |
| 1628 | unsigned long retain_target = get_retain_buffers(c); |
| 1629 | |
| 1630 | return (count < retain_target) ? 0 : (count - retain_target); |
| 1631 | } |
| 1632 | |
| 1633 | /* |
| 1634 | * Create the buffering interface |
| 1635 | */ |
| 1636 | struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size, |
| 1637 | unsigned reserved_buffers, unsigned aux_size, |
| 1638 | void (*alloc_callback)(struct dm_buffer *), |
| 1639 | void (*write_callback)(struct dm_buffer *)) |
| 1640 | { |
| 1641 | int r; |
| 1642 | struct dm_bufio_client *c; |
| 1643 | unsigned i; |
| 1644 | |
| 1645 | BUG_ON(block_size < 1 << SECTOR_SHIFT || |
| 1646 | (block_size & (block_size - 1))); |
| 1647 | |
| 1648 | c = kzalloc(sizeof(*c), GFP_KERNEL); |
| 1649 | if (!c) { |
| 1650 | r = -ENOMEM; |
| 1651 | goto bad_client; |
| 1652 | } |
| 1653 | c->buffer_tree = RB_ROOT; |
| 1654 | |
| 1655 | c->bdev = bdev; |
| 1656 | c->block_size = block_size; |
| 1657 | c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; |
| 1658 | c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ? |
| 1659 | __ffs(block_size) - PAGE_SHIFT : 0; |
| 1660 | |
| 1661 | c->aux_size = aux_size; |
| 1662 | c->alloc_callback = alloc_callback; |
| 1663 | c->write_callback = write_callback; |
| 1664 | |
| 1665 | for (i = 0; i < LIST_SIZE; i++) { |
| 1666 | INIT_LIST_HEAD(&c->lru[i]); |
| 1667 | c->n_buffers[i] = 0; |
| 1668 | } |
| 1669 | |
| 1670 | mutex_init(&c->lock); |
| 1671 | INIT_LIST_HEAD(&c->reserved_buffers); |
| 1672 | c->need_reserved_buffers = reserved_buffers; |
| 1673 | |
| 1674 | dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS); |
| 1675 | |
| 1676 | init_waitqueue_head(&c->free_buffer_wait); |
| 1677 | c->async_write_error = 0; |
| 1678 | |
| 1679 | c->dm_io = dm_io_client_create(); |
| 1680 | if (IS_ERR(c->dm_io)) { |
| 1681 | r = PTR_ERR(c->dm_io); |
| 1682 | goto bad_dm_io; |
| 1683 | } |
| 1684 | |
| 1685 | if (block_size < PAGE_SIZE) { |
| 1686 | char name[26]; |
| 1687 | snprintf(name, sizeof name, "dm_bufio_cache-%u", c->block_size); |
| 1688 | c->slab_cache = kmem_cache_create(name, c->block_size, ARCH_KMALLOC_MINALIGN, |
| 1689 | SLAB_RECLAIM_ACCOUNT, NULL); |
| 1690 | if (!c->slab_cache) { |
| 1691 | r = -ENOMEM; |
| 1692 | goto bad; |
| 1693 | } |
| 1694 | } |
| 1695 | |
| 1696 | while (c->need_reserved_buffers) { |
| 1697 | struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); |
| 1698 | |
| 1699 | if (!b) { |
| 1700 | r = -ENOMEM; |
| 1701 | goto bad; |
| 1702 | } |
| 1703 | __free_buffer_wake(b); |
| 1704 | } |
| 1705 | |
| 1706 | c->shrinker.count_objects = dm_bufio_shrink_count; |
| 1707 | c->shrinker.scan_objects = dm_bufio_shrink_scan; |
| 1708 | c->shrinker.seeks = 1; |
| 1709 | c->shrinker.batch = 0; |
| 1710 | r = register_shrinker(&c->shrinker); |
| 1711 | if (r) |
| 1712 | goto bad; |
| 1713 | |
| 1714 | mutex_lock(&dm_bufio_clients_lock); |
| 1715 | dm_bufio_client_count++; |
| 1716 | list_add(&c->client_list, &dm_bufio_all_clients); |
| 1717 | __cache_size_refresh(); |
| 1718 | mutex_unlock(&dm_bufio_clients_lock); |
| 1719 | |
| 1720 | return c; |
| 1721 | |
| 1722 | bad: |
| 1723 | while (!list_empty(&c->reserved_buffers)) { |
| 1724 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, |
| 1725 | struct dm_buffer, lru_list); |
| 1726 | list_del(&b->lru_list); |
| 1727 | free_buffer(b); |
| 1728 | } |
| 1729 | kmem_cache_destroy(c->slab_cache); |
| 1730 | dm_io_client_destroy(c->dm_io); |
| 1731 | bad_dm_io: |
| 1732 | mutex_destroy(&c->lock); |
| 1733 | kfree(c); |
| 1734 | bad_client: |
| 1735 | return ERR_PTR(r); |
| 1736 | } |
| 1737 | EXPORT_SYMBOL_GPL(dm_bufio_client_create); |
| 1738 | |
| 1739 | /* |
| 1740 | * Free the buffering interface. |
| 1741 | * It is required that there are no references on any buffers. |
| 1742 | */ |
| 1743 | void dm_bufio_client_destroy(struct dm_bufio_client *c) |
| 1744 | { |
| 1745 | unsigned i; |
| 1746 | |
| 1747 | drop_buffers(c); |
| 1748 | |
| 1749 | unregister_shrinker(&c->shrinker); |
| 1750 | |
| 1751 | mutex_lock(&dm_bufio_clients_lock); |
| 1752 | |
| 1753 | list_del(&c->client_list); |
| 1754 | dm_bufio_client_count--; |
| 1755 | __cache_size_refresh(); |
| 1756 | |
| 1757 | mutex_unlock(&dm_bufio_clients_lock); |
| 1758 | |
| 1759 | BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree)); |
| 1760 | BUG_ON(c->need_reserved_buffers); |
| 1761 | |
| 1762 | while (!list_empty(&c->reserved_buffers)) { |
| 1763 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, |
| 1764 | struct dm_buffer, lru_list); |
| 1765 | list_del(&b->lru_list); |
| 1766 | free_buffer(b); |
| 1767 | } |
| 1768 | |
| 1769 | for (i = 0; i < LIST_SIZE; i++) |
| 1770 | if (c->n_buffers[i]) |
| 1771 | DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); |
| 1772 | |
| 1773 | for (i = 0; i < LIST_SIZE; i++) |
| 1774 | BUG_ON(c->n_buffers[i]); |
| 1775 | |
| 1776 | kmem_cache_destroy(c->slab_cache); |
| 1777 | dm_io_client_destroy(c->dm_io); |
| 1778 | mutex_destroy(&c->lock); |
| 1779 | kfree(c); |
| 1780 | } |
| 1781 | EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); |
| 1782 | |
| 1783 | void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) |
| 1784 | { |
| 1785 | c->start = start; |
| 1786 | } |
| 1787 | EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset); |
| 1788 | |
| 1789 | static unsigned get_max_age_hz(void) |
| 1790 | { |
| 1791 | unsigned max_age = READ_ONCE(dm_bufio_max_age); |
| 1792 | |
| 1793 | if (max_age > UINT_MAX / HZ) |
| 1794 | max_age = UINT_MAX / HZ; |
| 1795 | |
| 1796 | return max_age * HZ; |
| 1797 | } |
| 1798 | |
| 1799 | static bool older_than(struct dm_buffer *b, unsigned long age_hz) |
| 1800 | { |
| 1801 | return time_after_eq(jiffies, b->last_accessed + age_hz); |
| 1802 | } |
| 1803 | |
| 1804 | static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) |
| 1805 | { |
| 1806 | struct dm_buffer *b, *tmp; |
| 1807 | unsigned long retain_target = get_retain_buffers(c); |
| 1808 | unsigned long count; |
| 1809 | LIST_HEAD(write_list); |
| 1810 | |
| 1811 | dm_bufio_lock(c); |
| 1812 | |
| 1813 | __check_watermark(c, &write_list); |
| 1814 | if (unlikely(!list_empty(&write_list))) { |
| 1815 | dm_bufio_unlock(c); |
| 1816 | __flush_write_list(&write_list); |
| 1817 | dm_bufio_lock(c); |
| 1818 | } |
| 1819 | |
| 1820 | count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; |
| 1821 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { |
| 1822 | if (count <= retain_target) |
| 1823 | break; |
| 1824 | |
| 1825 | if (!older_than(b, age_hz)) |
| 1826 | break; |
| 1827 | |
| 1828 | if (__try_evict_buffer(b, 0)) |
| 1829 | count--; |
| 1830 | |
| 1831 | cond_resched(); |
| 1832 | } |
| 1833 | |
| 1834 | dm_bufio_unlock(c); |
| 1835 | } |
| 1836 | |
| 1837 | static void cleanup_old_buffers(void) |
| 1838 | { |
| 1839 | unsigned long max_age_hz = get_max_age_hz(); |
| 1840 | struct dm_bufio_client *c; |
| 1841 | |
| 1842 | mutex_lock(&dm_bufio_clients_lock); |
| 1843 | |
| 1844 | __cache_size_refresh(); |
| 1845 | |
| 1846 | list_for_each_entry(c, &dm_bufio_all_clients, client_list) |
| 1847 | __evict_old_buffers(c, max_age_hz); |
| 1848 | |
| 1849 | mutex_unlock(&dm_bufio_clients_lock); |
| 1850 | } |
| 1851 | |
| 1852 | static struct workqueue_struct *dm_bufio_wq; |
| 1853 | static struct delayed_work dm_bufio_work; |
| 1854 | |
| 1855 | static void work_fn(struct work_struct *w) |
| 1856 | { |
| 1857 | cleanup_old_buffers(); |
| 1858 | |
| 1859 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, |
| 1860 | DM_BUFIO_WORK_TIMER_SECS * HZ); |
| 1861 | } |
| 1862 | |
| 1863 | /*---------------------------------------------------------------- |
| 1864 | * Module setup |
| 1865 | *--------------------------------------------------------------*/ |
| 1866 | |
| 1867 | /* |
| 1868 | * This is called only once for the whole dm_bufio module. |
| 1869 | * It initializes memory limit. |
| 1870 | */ |
| 1871 | static int __init dm_bufio_init(void) |
| 1872 | { |
| 1873 | __u64 mem; |
| 1874 | |
| 1875 | dm_bufio_allocated_kmem_cache = 0; |
| 1876 | dm_bufio_allocated_get_free_pages = 0; |
| 1877 | dm_bufio_allocated_vmalloc = 0; |
| 1878 | dm_bufio_current_allocated = 0; |
| 1879 | |
| 1880 | mem = (__u64)mult_frac(totalram_pages - totalhigh_pages, |
| 1881 | DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT; |
| 1882 | |
| 1883 | if (mem > ULONG_MAX) |
| 1884 | mem = ULONG_MAX; |
| 1885 | |
| 1886 | #ifdef CONFIG_MMU |
| 1887 | if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100)) |
| 1888 | mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100); |
| 1889 | #endif |
| 1890 | |
| 1891 | dm_bufio_default_cache_size = mem; |
| 1892 | |
| 1893 | mutex_lock(&dm_bufio_clients_lock); |
| 1894 | __cache_size_refresh(); |
| 1895 | mutex_unlock(&dm_bufio_clients_lock); |
| 1896 | |
| 1897 | dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0); |
| 1898 | if (!dm_bufio_wq) |
| 1899 | return -ENOMEM; |
| 1900 | |
| 1901 | INIT_DELAYED_WORK(&dm_bufio_work, work_fn); |
| 1902 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, |
| 1903 | DM_BUFIO_WORK_TIMER_SECS * HZ); |
| 1904 | |
| 1905 | return 0; |
| 1906 | } |
| 1907 | |
| 1908 | /* |
| 1909 | * This is called once when unloading the dm_bufio module. |
| 1910 | */ |
| 1911 | static void __exit dm_bufio_exit(void) |
| 1912 | { |
| 1913 | int bug = 0; |
| 1914 | |
| 1915 | cancel_delayed_work_sync(&dm_bufio_work); |
| 1916 | destroy_workqueue(dm_bufio_wq); |
| 1917 | |
| 1918 | if (dm_bufio_client_count) { |
| 1919 | DMCRIT("%s: dm_bufio_client_count leaked: %d", |
| 1920 | __func__, dm_bufio_client_count); |
| 1921 | bug = 1; |
| 1922 | } |
| 1923 | |
| 1924 | if (dm_bufio_current_allocated) { |
| 1925 | DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", |
| 1926 | __func__, dm_bufio_current_allocated); |
| 1927 | bug = 1; |
| 1928 | } |
| 1929 | |
| 1930 | if (dm_bufio_allocated_get_free_pages) { |
| 1931 | DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", |
| 1932 | __func__, dm_bufio_allocated_get_free_pages); |
| 1933 | bug = 1; |
| 1934 | } |
| 1935 | |
| 1936 | if (dm_bufio_allocated_vmalloc) { |
| 1937 | DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", |
| 1938 | __func__, dm_bufio_allocated_vmalloc); |
| 1939 | bug = 1; |
| 1940 | } |
| 1941 | |
| 1942 | BUG_ON(bug); |
| 1943 | } |
| 1944 | |
| 1945 | module_init(dm_bufio_init) |
| 1946 | module_exit(dm_bufio_exit) |
| 1947 | |
| 1948 | module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR); |
| 1949 | MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); |
| 1950 | |
| 1951 | module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR); |
| 1952 | MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); |
| 1953 | |
| 1954 | module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR); |
| 1955 | MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory"); |
| 1956 | |
| 1957 | module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR); |
| 1958 | MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); |
| 1959 | |
| 1960 | module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO); |
| 1961 | MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); |
| 1962 | |
| 1963 | module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO); |
| 1964 | MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); |
| 1965 | |
| 1966 | module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO); |
| 1967 | MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); |
| 1968 | |
| 1969 | module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO); |
| 1970 | MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); |
| 1971 | |
| 1972 | MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); |
| 1973 | MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); |
| 1974 | MODULE_LICENSE("GPL"); |