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, *sizes_ptr; 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 sizes_ptr = kmap_local_page(pages[0]); 262 write_compress_length(sizes_ptr, tot_out); 263 kunmap_local(sizes_ptr); 264 265 ret = 0; 266 *total_out = tot_out; 267 *total_in = tot_in; 268 out: 269 *out_pages = nr_pages; 270 if (out_page) 271 kunmap(out_page); 272 273 if (in_page) { 274 kunmap(in_page); 275 put_page(in_page); 276 } 277 278 return ret; 279 } 280 281 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 282 { 283 struct workspace *workspace = list_entry(ws, struct workspace, list); 284 int ret = 0, ret2; 285 char *data_in; 286 unsigned long page_in_index = 0; 287 size_t srclen = cb->compressed_len; 288 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 289 unsigned long buf_start; 290 unsigned long buf_offset = 0; 291 unsigned long bytes; 292 unsigned long working_bytes; 293 size_t in_len; 294 size_t out_len; 295 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 296 unsigned long in_offset; 297 unsigned long in_page_bytes_left; 298 unsigned long tot_in; 299 unsigned long tot_out; 300 unsigned long tot_len; 301 char *buf; 302 bool may_late_unmap, need_unmap; 303 struct page **pages_in = cb->compressed_pages; 304 u64 disk_start = cb->start; 305 struct bio *orig_bio = cb->orig_bio; 306 307 data_in = kmap(pages_in[0]); 308 tot_len = read_compress_length(data_in); 309 /* 310 * Compressed data header check. 311 * 312 * The real compressed size can't exceed the maximum extent length, and 313 * all pages should be used (whole unused page with just the segment 314 * header is not possible). If this happens it means the compressed 315 * extent is corrupted. 316 */ 317 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) || 318 tot_len < srclen - PAGE_SIZE) { 319 ret = -EUCLEAN; 320 goto done; 321 } 322 323 tot_in = LZO_LEN; 324 in_offset = LZO_LEN; 325 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 326 327 tot_out = 0; 328 329 while (tot_in < tot_len) { 330 in_len = read_compress_length(data_in + in_offset); 331 in_page_bytes_left -= LZO_LEN; 332 in_offset += LZO_LEN; 333 tot_in += LZO_LEN; 334 335 /* 336 * Segment header check. 337 * 338 * The segment length must not exceed the maximum LZO 339 * compression size, nor the total compressed size. 340 */ 341 if (in_len > max_segment_len || tot_in + in_len > tot_len) { 342 ret = -EUCLEAN; 343 goto done; 344 } 345 346 tot_in += in_len; 347 working_bytes = in_len; 348 may_late_unmap = need_unmap = false; 349 350 /* fast path: avoid using the working buffer */ 351 if (in_page_bytes_left >= in_len) { 352 buf = data_in + in_offset; 353 bytes = in_len; 354 may_late_unmap = true; 355 goto cont; 356 } 357 358 /* copy bytes from the pages into the working buffer */ 359 buf = workspace->cbuf; 360 buf_offset = 0; 361 while (working_bytes) { 362 bytes = min(working_bytes, in_page_bytes_left); 363 364 memcpy(buf + buf_offset, data_in + in_offset, bytes); 365 buf_offset += bytes; 366 cont: 367 working_bytes -= bytes; 368 in_page_bytes_left -= bytes; 369 in_offset += bytes; 370 371 /* check if we need to pick another page */ 372 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 373 || in_page_bytes_left == 0) { 374 tot_in += in_page_bytes_left; 375 376 if (working_bytes == 0 && tot_in >= tot_len) 377 break; 378 379 if (page_in_index + 1 >= total_pages_in) { 380 ret = -EIO; 381 goto done; 382 } 383 384 if (may_late_unmap) 385 need_unmap = true; 386 else 387 kunmap(pages_in[page_in_index]); 388 389 data_in = kmap(pages_in[++page_in_index]); 390 391 in_page_bytes_left = PAGE_SIZE; 392 in_offset = 0; 393 } 394 } 395 396 out_len = max_segment_len; 397 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 398 &out_len); 399 if (need_unmap) 400 kunmap(pages_in[page_in_index - 1]); 401 if (ret != LZO_E_OK) { 402 pr_warn("BTRFS: decompress failed\n"); 403 ret = -EIO; 404 break; 405 } 406 407 buf_start = tot_out; 408 tot_out += out_len; 409 410 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 411 tot_out, disk_start, orig_bio); 412 if (ret2 == 0) 413 break; 414 } 415 done: 416 kunmap(pages_in[page_in_index]); 417 if (!ret) 418 zero_fill_bio(orig_bio); 419 return ret; 420 } 421 422 int lzo_decompress(struct list_head *ws, unsigned char *data_in, 423 struct page *dest_page, unsigned long start_byte, size_t srclen, 424 size_t destlen) 425 { 426 struct workspace *workspace = list_entry(ws, struct workspace, list); 427 size_t in_len; 428 size_t out_len; 429 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 430 int ret = 0; 431 char *kaddr; 432 unsigned long bytes; 433 434 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2) 435 return -EUCLEAN; 436 437 in_len = read_compress_length(data_in); 438 if (in_len != srclen) 439 return -EUCLEAN; 440 data_in += LZO_LEN; 441 442 in_len = read_compress_length(data_in); 443 if (in_len != srclen - LZO_LEN * 2) { 444 ret = -EUCLEAN; 445 goto out; 446 } 447 data_in += LZO_LEN; 448 449 out_len = PAGE_SIZE; 450 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 451 if (ret != LZO_E_OK) { 452 pr_warn("BTRFS: decompress failed!\n"); 453 ret = -EIO; 454 goto out; 455 } 456 457 if (out_len < start_byte) { 458 ret = -EIO; 459 goto out; 460 } 461 462 /* 463 * the caller is already checking against PAGE_SIZE, but lets 464 * move this check closer to the memcpy/memset 465 */ 466 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 467 bytes = min_t(unsigned long, destlen, out_len - start_byte); 468 469 kaddr = kmap_local_page(dest_page); 470 memcpy(kaddr, workspace->buf + start_byte, bytes); 471 472 /* 473 * btrfs_getblock is doing a zero on the tail of the page too, 474 * but this will cover anything missing from the decompressed 475 * data. 476 */ 477 if (bytes < destlen) 478 memset(kaddr+bytes, 0, destlen-bytes); 479 kunmap_local(kaddr); 480 out: 481 return ret; 482 } 483 484 const struct btrfs_compress_op btrfs_lzo_compress = { 485 .workspace_manager = &wsm, 486 .max_level = 1, 487 .default_level = 1, 488 }; 489