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 void lzo_free_workspace(struct list_head *ws) 67 { 68 struct workspace *workspace = list_entry(ws, struct workspace, list); 69 70 kvfree(workspace->buf); 71 kvfree(workspace->cbuf); 72 kvfree(workspace->mem); 73 kfree(workspace); 74 } 75 76 struct list_head *lzo_alloc_workspace(unsigned int level) 77 { 78 struct workspace *workspace; 79 80 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); 81 if (!workspace) 82 return ERR_PTR(-ENOMEM); 83 84 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); 85 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 86 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 87 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 88 goto fail; 89 90 INIT_LIST_HEAD(&workspace->list); 91 92 return &workspace->list; 93 fail: 94 lzo_free_workspace(&workspace->list); 95 return ERR_PTR(-ENOMEM); 96 } 97 98 static inline void write_compress_length(char *buf, size_t len) 99 { 100 __le32 dlen; 101 102 dlen = cpu_to_le32(len); 103 memcpy(buf, &dlen, LZO_LEN); 104 } 105 106 static inline size_t read_compress_length(const char *buf) 107 { 108 __le32 dlen; 109 110 memcpy(&dlen, buf, LZO_LEN); 111 return le32_to_cpu(dlen); 112 } 113 114 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 115 u64 start, struct page **pages, unsigned long *out_pages, 116 unsigned long *total_in, unsigned long *total_out) 117 { 118 struct workspace *workspace = list_entry(ws, struct workspace, list); 119 int ret = 0; 120 char *data_in; 121 char *cpage_out; 122 int nr_pages = 0; 123 struct page *in_page = NULL; 124 struct page *out_page = NULL; 125 unsigned long bytes_left; 126 unsigned long len = *total_out; 127 unsigned long nr_dest_pages = *out_pages; 128 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 129 size_t in_len; 130 size_t out_len; 131 char *buf; 132 unsigned long tot_in = 0; 133 unsigned long tot_out = 0; 134 unsigned long pg_bytes_left; 135 unsigned long out_offset; 136 unsigned long bytes; 137 138 *out_pages = 0; 139 *total_out = 0; 140 *total_in = 0; 141 142 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 143 data_in = kmap(in_page); 144 145 /* 146 * store the size of all chunks of compressed data in 147 * the first 4 bytes 148 */ 149 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 150 if (out_page == NULL) { 151 ret = -ENOMEM; 152 goto out; 153 } 154 cpage_out = kmap(out_page); 155 out_offset = LZO_LEN; 156 tot_out = LZO_LEN; 157 pages[0] = out_page; 158 nr_pages = 1; 159 pg_bytes_left = PAGE_SIZE - LZO_LEN; 160 161 /* compress at most one page of data each time */ 162 in_len = min(len, PAGE_SIZE); 163 while (tot_in < len) { 164 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 165 &out_len, workspace->mem); 166 if (ret != LZO_E_OK) { 167 pr_debug("BTRFS: lzo in loop returned %d\n", 168 ret); 169 ret = -EIO; 170 goto out; 171 } 172 173 /* store the size of this chunk of compressed data */ 174 write_compress_length(cpage_out + out_offset, out_len); 175 tot_out += LZO_LEN; 176 out_offset += LZO_LEN; 177 pg_bytes_left -= LZO_LEN; 178 179 tot_in += in_len; 180 tot_out += out_len; 181 182 /* copy bytes from the working buffer into the pages */ 183 buf = workspace->cbuf; 184 while (out_len) { 185 bytes = min_t(unsigned long, pg_bytes_left, out_len); 186 187 memcpy(cpage_out + out_offset, buf, bytes); 188 189 out_len -= bytes; 190 pg_bytes_left -= bytes; 191 buf += bytes; 192 out_offset += bytes; 193 194 /* 195 * we need another page for writing out. 196 * 197 * Note if there's less than 4 bytes left, we just 198 * skip to a new page. 199 */ 200 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 201 pg_bytes_left == 0) { 202 if (pg_bytes_left) { 203 memset(cpage_out + out_offset, 0, 204 pg_bytes_left); 205 tot_out += pg_bytes_left; 206 } 207 208 /* we're done, don't allocate new page */ 209 if (out_len == 0 && tot_in >= len) 210 break; 211 212 kunmap(out_page); 213 if (nr_pages == nr_dest_pages) { 214 out_page = NULL; 215 ret = -E2BIG; 216 goto out; 217 } 218 219 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 220 if (out_page == NULL) { 221 ret = -ENOMEM; 222 goto out; 223 } 224 cpage_out = kmap(out_page); 225 pages[nr_pages++] = out_page; 226 227 pg_bytes_left = PAGE_SIZE; 228 out_offset = 0; 229 } 230 } 231 232 /* we're making it bigger, give up */ 233 if (tot_in > 8192 && tot_in < tot_out) { 234 ret = -E2BIG; 235 goto out; 236 } 237 238 /* we're all done */ 239 if (tot_in >= len) 240 break; 241 242 if (tot_out > max_out) 243 break; 244 245 bytes_left = len - tot_in; 246 kunmap(in_page); 247 put_page(in_page); 248 249 start += PAGE_SIZE; 250 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 251 data_in = kmap(in_page); 252 in_len = min(bytes_left, PAGE_SIZE); 253 } 254 255 if (tot_out >= tot_in) { 256 ret = -E2BIG; 257 goto out; 258 } 259 260 /* store the size of all chunks of compressed data */ 261 cpage_out = kmap(pages[0]); 262 write_compress_length(cpage_out, tot_out); 263 264 kunmap(pages[0]); 265 266 ret = 0; 267 *total_out = tot_out; 268 *total_in = tot_in; 269 out: 270 *out_pages = nr_pages; 271 if (out_page) 272 kunmap(out_page); 273 274 if (in_page) { 275 kunmap(in_page); 276 put_page(in_page); 277 } 278 279 return ret; 280 } 281 282 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 283 { 284 struct workspace *workspace = list_entry(ws, struct workspace, list); 285 int ret = 0, ret2; 286 char *data_in; 287 unsigned long page_in_index = 0; 288 size_t srclen = cb->compressed_len; 289 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 290 unsigned long buf_start; 291 unsigned long buf_offset = 0; 292 unsigned long bytes; 293 unsigned long working_bytes; 294 size_t in_len; 295 size_t out_len; 296 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 297 unsigned long in_offset; 298 unsigned long in_page_bytes_left; 299 unsigned long tot_in; 300 unsigned long tot_out; 301 unsigned long tot_len; 302 char *buf; 303 bool may_late_unmap, need_unmap; 304 struct page **pages_in = cb->compressed_pages; 305 u64 disk_start = cb->start; 306 struct bio *orig_bio = cb->orig_bio; 307 308 data_in = kmap(pages_in[0]); 309 tot_len = read_compress_length(data_in); 310 /* 311 * Compressed data header check. 312 * 313 * The real compressed size can't exceed the maximum extent length, and 314 * all pages should be used (whole unused page with just the segment 315 * header is not possible). If this happens it means the compressed 316 * extent is corrupted. 317 */ 318 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) || 319 tot_len < srclen - PAGE_SIZE) { 320 ret = -EUCLEAN; 321 goto done; 322 } 323 324 tot_in = LZO_LEN; 325 in_offset = LZO_LEN; 326 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 327 328 tot_out = 0; 329 330 while (tot_in < tot_len) { 331 in_len = read_compress_length(data_in + in_offset); 332 in_page_bytes_left -= LZO_LEN; 333 in_offset += LZO_LEN; 334 tot_in += LZO_LEN; 335 336 /* 337 * Segment header check. 338 * 339 * The segment length must not exceed the maximum LZO 340 * compression size, nor the total compressed size. 341 */ 342 if (in_len > max_segment_len || tot_in + in_len > tot_len) { 343 ret = -EUCLEAN; 344 goto done; 345 } 346 347 tot_in += in_len; 348 working_bytes = in_len; 349 may_late_unmap = need_unmap = false; 350 351 /* fast path: avoid using the working buffer */ 352 if (in_page_bytes_left >= in_len) { 353 buf = data_in + in_offset; 354 bytes = in_len; 355 may_late_unmap = true; 356 goto cont; 357 } 358 359 /* copy bytes from the pages into the working buffer */ 360 buf = workspace->cbuf; 361 buf_offset = 0; 362 while (working_bytes) { 363 bytes = min(working_bytes, in_page_bytes_left); 364 365 memcpy(buf + buf_offset, data_in + in_offset, bytes); 366 buf_offset += bytes; 367 cont: 368 working_bytes -= bytes; 369 in_page_bytes_left -= bytes; 370 in_offset += bytes; 371 372 /* check if we need to pick another page */ 373 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 374 || in_page_bytes_left == 0) { 375 tot_in += in_page_bytes_left; 376 377 if (working_bytes == 0 && tot_in >= tot_len) 378 break; 379 380 if (page_in_index + 1 >= total_pages_in) { 381 ret = -EIO; 382 goto done; 383 } 384 385 if (may_late_unmap) 386 need_unmap = true; 387 else 388 kunmap(pages_in[page_in_index]); 389 390 data_in = kmap(pages_in[++page_in_index]); 391 392 in_page_bytes_left = PAGE_SIZE; 393 in_offset = 0; 394 } 395 } 396 397 out_len = max_segment_len; 398 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 399 &out_len); 400 if (need_unmap) 401 kunmap(pages_in[page_in_index - 1]); 402 if (ret != LZO_E_OK) { 403 pr_warn("BTRFS: decompress failed\n"); 404 ret = -EIO; 405 break; 406 } 407 408 buf_start = tot_out; 409 tot_out += out_len; 410 411 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 412 tot_out, disk_start, orig_bio); 413 if (ret2 == 0) 414 break; 415 } 416 done: 417 kunmap(pages_in[page_in_index]); 418 if (!ret) 419 zero_fill_bio(orig_bio); 420 return ret; 421 } 422 423 int lzo_decompress(struct list_head *ws, unsigned char *data_in, 424 struct page *dest_page, unsigned long start_byte, size_t srclen, 425 size_t destlen) 426 { 427 struct workspace *workspace = list_entry(ws, struct workspace, list); 428 size_t in_len; 429 size_t out_len; 430 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 431 int ret = 0; 432 char *kaddr; 433 unsigned long bytes; 434 435 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2) 436 return -EUCLEAN; 437 438 in_len = read_compress_length(data_in); 439 if (in_len != srclen) 440 return -EUCLEAN; 441 data_in += LZO_LEN; 442 443 in_len = read_compress_length(data_in); 444 if (in_len != srclen - LZO_LEN * 2) { 445 ret = -EUCLEAN; 446 goto out; 447 } 448 data_in += LZO_LEN; 449 450 out_len = PAGE_SIZE; 451 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 452 if (ret != LZO_E_OK) { 453 pr_warn("BTRFS: decompress failed!\n"); 454 ret = -EIO; 455 goto out; 456 } 457 458 if (out_len < start_byte) { 459 ret = -EIO; 460 goto out; 461 } 462 463 /* 464 * the caller is already checking against PAGE_SIZE, but lets 465 * move this check closer to the memcpy/memset 466 */ 467 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 468 bytes = min_t(unsigned long, destlen, out_len - start_byte); 469 470 kaddr = kmap_local_page(dest_page); 471 memcpy(kaddr, workspace->buf + start_byte, bytes); 472 473 /* 474 * btrfs_getblock is doing a zero on the tail of the page too, 475 * but this will cover anything missing from the decompressed 476 * data. 477 */ 478 if (bytes < destlen) 479 memset(kaddr+bytes, 0, destlen-bytes); 480 kunmap_local(kaddr); 481 out: 482 return ret; 483 } 484 485 const struct btrfs_compress_op btrfs_lzo_compress = { 486 .workspace_manager = &wsm, 487 .max_level = 1, 488 .default_level = 1, 489 }; 490