1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2008 Oracle. All rights reserved. 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/slab.h> 8 #include <linux/mm.h> 9 #include <linux/init.h> 10 #include <linux/err.h> 11 #include <linux/sched.h> 12 #include <linux/pagemap.h> 13 #include <linux/bio.h> 14 #include <linux/lzo.h> 15 #include <linux/refcount.h> 16 #include "compression.h" 17 18 #define LZO_LEN 4 19 20 /* 21 * Btrfs LZO compression format 22 * 23 * Regular and inlined LZO compressed data extents consist of: 24 * 25 * 1. Header 26 * Fixed size. LZO_LEN (4) bytes long, LE32. 27 * Records the total size (including the header) of compressed data. 28 * 29 * 2. Segment(s) 30 * Variable size. Each segment includes one segment header, followed by data 31 * payload. 32 * One regular LZO compressed extent can have one or more segments. 33 * For inlined LZO compressed extent, only one segment is allowed. 34 * One segment represents at most one page of uncompressed data. 35 * 36 * 2.1 Segment header 37 * Fixed size. LZO_LEN (4) bytes long, LE32. 38 * Records the total size of the segment (not including the header). 39 * Segment header never crosses page boundary, thus it's possible to 40 * have at most 3 padding zeros at the end of the page. 41 * 42 * 2.2 Data Payload 43 * Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE) 44 * which is 4419 for a 4KiB page. 45 * 46 * Example: 47 * Page 1: 48 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10 49 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... | 50 * ... 51 * 0x0ff0 | SegHdr N | Data payload N ... |00| 52 * ^^ padding zeros 53 * Page 2: 54 * 0x1000 | SegHdr N+1| Data payload N+1 ... | 55 */ 56 57 struct workspace { 58 void *mem; 59 void *buf; /* where decompressed data goes */ 60 void *cbuf; /* where compressed data goes */ 61 struct list_head list; 62 }; 63 64 static struct workspace_manager wsm; 65 66 static void lzo_init_workspace_manager(void) 67 { 68 btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress); 69 } 70 71 static void lzo_cleanup_workspace_manager(void) 72 { 73 btrfs_cleanup_workspace_manager(&wsm); 74 } 75 76 static struct list_head *lzo_get_workspace(unsigned int level) 77 { 78 return btrfs_get_workspace(&wsm, level); 79 } 80 81 static void lzo_put_workspace(struct list_head *ws) 82 { 83 btrfs_put_workspace(&wsm, ws); 84 } 85 86 static void lzo_free_workspace(struct list_head *ws) 87 { 88 struct workspace *workspace = list_entry(ws, struct workspace, list); 89 90 kvfree(workspace->buf); 91 kvfree(workspace->cbuf); 92 kvfree(workspace->mem); 93 kfree(workspace); 94 } 95 96 static struct list_head *lzo_alloc_workspace(unsigned int level) 97 { 98 struct workspace *workspace; 99 100 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); 101 if (!workspace) 102 return ERR_PTR(-ENOMEM); 103 104 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); 105 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 106 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 107 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 108 goto fail; 109 110 INIT_LIST_HEAD(&workspace->list); 111 112 return &workspace->list; 113 fail: 114 lzo_free_workspace(&workspace->list); 115 return ERR_PTR(-ENOMEM); 116 } 117 118 static inline void write_compress_length(char *buf, size_t len) 119 { 120 __le32 dlen; 121 122 dlen = cpu_to_le32(len); 123 memcpy(buf, &dlen, LZO_LEN); 124 } 125 126 static inline size_t read_compress_length(const char *buf) 127 { 128 __le32 dlen; 129 130 memcpy(&dlen, buf, LZO_LEN); 131 return le32_to_cpu(dlen); 132 } 133 134 static int lzo_compress_pages(struct list_head *ws, 135 struct address_space *mapping, 136 u64 start, 137 struct page **pages, 138 unsigned long *out_pages, 139 unsigned long *total_in, 140 unsigned long *total_out) 141 { 142 struct workspace *workspace = list_entry(ws, struct workspace, list); 143 int ret = 0; 144 char *data_in; 145 char *cpage_out; 146 int nr_pages = 0; 147 struct page *in_page = NULL; 148 struct page *out_page = NULL; 149 unsigned long bytes_left; 150 unsigned long len = *total_out; 151 unsigned long nr_dest_pages = *out_pages; 152 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 153 size_t in_len; 154 size_t out_len; 155 char *buf; 156 unsigned long tot_in = 0; 157 unsigned long tot_out = 0; 158 unsigned long pg_bytes_left; 159 unsigned long out_offset; 160 unsigned long bytes; 161 162 *out_pages = 0; 163 *total_out = 0; 164 *total_in = 0; 165 166 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 167 data_in = kmap(in_page); 168 169 /* 170 * store the size of all chunks of compressed data in 171 * the first 4 bytes 172 */ 173 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 174 if (out_page == NULL) { 175 ret = -ENOMEM; 176 goto out; 177 } 178 cpage_out = kmap(out_page); 179 out_offset = LZO_LEN; 180 tot_out = LZO_LEN; 181 pages[0] = out_page; 182 nr_pages = 1; 183 pg_bytes_left = PAGE_SIZE - LZO_LEN; 184 185 /* compress at most one page of data each time */ 186 in_len = min(len, PAGE_SIZE); 187 while (tot_in < len) { 188 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 189 &out_len, workspace->mem); 190 if (ret != LZO_E_OK) { 191 pr_debug("BTRFS: lzo in loop returned %d\n", 192 ret); 193 ret = -EIO; 194 goto out; 195 } 196 197 /* store the size of this chunk of compressed data */ 198 write_compress_length(cpage_out + out_offset, out_len); 199 tot_out += LZO_LEN; 200 out_offset += LZO_LEN; 201 pg_bytes_left -= LZO_LEN; 202 203 tot_in += in_len; 204 tot_out += out_len; 205 206 /* copy bytes from the working buffer into the pages */ 207 buf = workspace->cbuf; 208 while (out_len) { 209 bytes = min_t(unsigned long, pg_bytes_left, out_len); 210 211 memcpy(cpage_out + out_offset, buf, bytes); 212 213 out_len -= bytes; 214 pg_bytes_left -= bytes; 215 buf += bytes; 216 out_offset += bytes; 217 218 /* 219 * we need another page for writing out. 220 * 221 * Note if there's less than 4 bytes left, we just 222 * skip to a new page. 223 */ 224 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 225 pg_bytes_left == 0) { 226 if (pg_bytes_left) { 227 memset(cpage_out + out_offset, 0, 228 pg_bytes_left); 229 tot_out += pg_bytes_left; 230 } 231 232 /* we're done, don't allocate new page */ 233 if (out_len == 0 && tot_in >= len) 234 break; 235 236 kunmap(out_page); 237 if (nr_pages == nr_dest_pages) { 238 out_page = NULL; 239 ret = -E2BIG; 240 goto out; 241 } 242 243 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 244 if (out_page == NULL) { 245 ret = -ENOMEM; 246 goto out; 247 } 248 cpage_out = kmap(out_page); 249 pages[nr_pages++] = out_page; 250 251 pg_bytes_left = PAGE_SIZE; 252 out_offset = 0; 253 } 254 } 255 256 /* we're making it bigger, give up */ 257 if (tot_in > 8192 && tot_in < tot_out) { 258 ret = -E2BIG; 259 goto out; 260 } 261 262 /* we're all done */ 263 if (tot_in >= len) 264 break; 265 266 if (tot_out > max_out) 267 break; 268 269 bytes_left = len - tot_in; 270 kunmap(in_page); 271 put_page(in_page); 272 273 start += PAGE_SIZE; 274 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 275 data_in = kmap(in_page); 276 in_len = min(bytes_left, PAGE_SIZE); 277 } 278 279 if (tot_out >= tot_in) { 280 ret = -E2BIG; 281 goto out; 282 } 283 284 /* store the size of all chunks of compressed data */ 285 cpage_out = kmap(pages[0]); 286 write_compress_length(cpage_out, tot_out); 287 288 kunmap(pages[0]); 289 290 ret = 0; 291 *total_out = tot_out; 292 *total_in = tot_in; 293 out: 294 *out_pages = nr_pages; 295 if (out_page) 296 kunmap(out_page); 297 298 if (in_page) { 299 kunmap(in_page); 300 put_page(in_page); 301 } 302 303 return ret; 304 } 305 306 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 307 { 308 struct workspace *workspace = list_entry(ws, struct workspace, list); 309 int ret = 0, ret2; 310 char *data_in; 311 unsigned long page_in_index = 0; 312 size_t srclen = cb->compressed_len; 313 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 314 unsigned long buf_start; 315 unsigned long buf_offset = 0; 316 unsigned long bytes; 317 unsigned long working_bytes; 318 size_t in_len; 319 size_t out_len; 320 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 321 unsigned long in_offset; 322 unsigned long in_page_bytes_left; 323 unsigned long tot_in; 324 unsigned long tot_out; 325 unsigned long tot_len; 326 char *buf; 327 bool may_late_unmap, need_unmap; 328 struct page **pages_in = cb->compressed_pages; 329 u64 disk_start = cb->start; 330 struct bio *orig_bio = cb->orig_bio; 331 332 data_in = kmap(pages_in[0]); 333 tot_len = read_compress_length(data_in); 334 /* 335 * Compressed data header check. 336 * 337 * The real compressed size can't exceed the maximum extent length, and 338 * all pages should be used (whole unused page with just the segment 339 * header is not possible). If this happens it means the compressed 340 * extent is corrupted. 341 */ 342 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) || 343 tot_len < srclen - PAGE_SIZE) { 344 ret = -EUCLEAN; 345 goto done; 346 } 347 348 tot_in = LZO_LEN; 349 in_offset = LZO_LEN; 350 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 351 352 tot_out = 0; 353 354 while (tot_in < tot_len) { 355 in_len = read_compress_length(data_in + in_offset); 356 in_page_bytes_left -= LZO_LEN; 357 in_offset += LZO_LEN; 358 tot_in += LZO_LEN; 359 360 /* 361 * Segment header check. 362 * 363 * The segment length must not exceed the maximum LZO 364 * compression size, nor the total compressed size. 365 */ 366 if (in_len > max_segment_len || tot_in + in_len > tot_len) { 367 ret = -EUCLEAN; 368 goto done; 369 } 370 371 tot_in += in_len; 372 working_bytes = in_len; 373 may_late_unmap = need_unmap = false; 374 375 /* fast path: avoid using the working buffer */ 376 if (in_page_bytes_left >= in_len) { 377 buf = data_in + in_offset; 378 bytes = in_len; 379 may_late_unmap = true; 380 goto cont; 381 } 382 383 /* copy bytes from the pages into the working buffer */ 384 buf = workspace->cbuf; 385 buf_offset = 0; 386 while (working_bytes) { 387 bytes = min(working_bytes, in_page_bytes_left); 388 389 memcpy(buf + buf_offset, data_in + in_offset, bytes); 390 buf_offset += bytes; 391 cont: 392 working_bytes -= bytes; 393 in_page_bytes_left -= bytes; 394 in_offset += bytes; 395 396 /* check if we need to pick another page */ 397 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 398 || in_page_bytes_left == 0) { 399 tot_in += in_page_bytes_left; 400 401 if (working_bytes == 0 && tot_in >= tot_len) 402 break; 403 404 if (page_in_index + 1 >= total_pages_in) { 405 ret = -EIO; 406 goto done; 407 } 408 409 if (may_late_unmap) 410 need_unmap = true; 411 else 412 kunmap(pages_in[page_in_index]); 413 414 data_in = kmap(pages_in[++page_in_index]); 415 416 in_page_bytes_left = PAGE_SIZE; 417 in_offset = 0; 418 } 419 } 420 421 out_len = max_segment_len; 422 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 423 &out_len); 424 if (need_unmap) 425 kunmap(pages_in[page_in_index - 1]); 426 if (ret != LZO_E_OK) { 427 pr_warn("BTRFS: decompress failed\n"); 428 ret = -EIO; 429 break; 430 } 431 432 buf_start = tot_out; 433 tot_out += out_len; 434 435 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 436 tot_out, disk_start, orig_bio); 437 if (ret2 == 0) 438 break; 439 } 440 done: 441 kunmap(pages_in[page_in_index]); 442 if (!ret) 443 zero_fill_bio(orig_bio); 444 return ret; 445 } 446 447 static int lzo_decompress(struct list_head *ws, unsigned char *data_in, 448 struct page *dest_page, 449 unsigned long start_byte, 450 size_t srclen, size_t destlen) 451 { 452 struct workspace *workspace = list_entry(ws, struct workspace, list); 453 size_t in_len; 454 size_t out_len; 455 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 456 int ret = 0; 457 char *kaddr; 458 unsigned long bytes; 459 460 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2) 461 return -EUCLEAN; 462 463 in_len = read_compress_length(data_in); 464 if (in_len != srclen) 465 return -EUCLEAN; 466 data_in += LZO_LEN; 467 468 in_len = read_compress_length(data_in); 469 if (in_len != srclen - LZO_LEN * 2) { 470 ret = -EUCLEAN; 471 goto out; 472 } 473 data_in += LZO_LEN; 474 475 out_len = PAGE_SIZE; 476 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 477 if (ret != LZO_E_OK) { 478 pr_warn("BTRFS: decompress failed!\n"); 479 ret = -EIO; 480 goto out; 481 } 482 483 if (out_len < start_byte) { 484 ret = -EIO; 485 goto out; 486 } 487 488 /* 489 * the caller is already checking against PAGE_SIZE, but lets 490 * move this check closer to the memcpy/memset 491 */ 492 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 493 bytes = min_t(unsigned long, destlen, out_len - start_byte); 494 495 kaddr = kmap_atomic(dest_page); 496 memcpy(kaddr, workspace->buf + start_byte, bytes); 497 498 /* 499 * btrfs_getblock is doing a zero on the tail of the page too, 500 * but this will cover anything missing from the decompressed 501 * data. 502 */ 503 if (bytes < destlen) 504 memset(kaddr+bytes, 0, destlen-bytes); 505 kunmap_atomic(kaddr); 506 out: 507 return ret; 508 } 509 510 const struct btrfs_compress_op btrfs_lzo_compress = { 511 .init_workspace_manager = lzo_init_workspace_manager, 512 .cleanup_workspace_manager = lzo_cleanup_workspace_manager, 513 .get_workspace = lzo_get_workspace, 514 .put_workspace = lzo_put_workspace, 515 .alloc_workspace = lzo_alloc_workspace, 516 .free_workspace = lzo_free_workspace, 517 .compress_pages = lzo_compress_pages, 518 .decompress_bio = lzo_decompress_bio, 519 .decompress = lzo_decompress, 520 .max_level = 1, 521 .default_level = 1, 522 }; 523