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 #include "ctree.h" 18 19 #define LZO_LEN 4 20 21 /* 22 * Btrfs LZO compression format 23 * 24 * Regular and inlined LZO compressed data extents consist of: 25 * 26 * 1. Header 27 * Fixed size. LZO_LEN (4) bytes long, LE32. 28 * Records the total size (including the header) of compressed data. 29 * 30 * 2. Segment(s) 31 * Variable size. Each segment includes one segment header, followed by data 32 * payload. 33 * One regular LZO compressed extent can have one or more segments. 34 * For inlined LZO compressed extent, only one segment is allowed. 35 * One segment represents at most one page of uncompressed data. 36 * 37 * 2.1 Segment header 38 * Fixed size. LZO_LEN (4) bytes long, LE32. 39 * Records the total size of the segment (not including the header). 40 * Segment header never crosses page boundary, thus it's possible to 41 * have at most 3 padding zeros at the end of the page. 42 * 43 * 2.2 Data Payload 44 * Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE) 45 * which is 4419 for a 4KiB page. 46 * 47 * Example: 48 * Page 1: 49 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10 50 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... | 51 * ... 52 * 0x0ff0 | SegHdr N | Data payload N ... |00| 53 * ^^ padding zeros 54 * Page 2: 55 * 0x1000 | SegHdr N+1| Data payload N+1 ... | 56 */ 57 58 struct workspace { 59 void *mem; 60 void *buf; /* where decompressed data goes */ 61 void *cbuf; /* where compressed data goes */ 62 struct list_head list; 63 }; 64 65 static struct workspace_manager wsm; 66 67 void lzo_free_workspace(struct list_head *ws) 68 { 69 struct workspace *workspace = list_entry(ws, struct workspace, list); 70 71 kvfree(workspace->buf); 72 kvfree(workspace->cbuf); 73 kvfree(workspace->mem); 74 kfree(workspace); 75 } 76 77 struct list_head *lzo_alloc_workspace(unsigned int level) 78 { 79 struct workspace *workspace; 80 81 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); 82 if (!workspace) 83 return ERR_PTR(-ENOMEM); 84 85 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); 86 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 87 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 88 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 89 goto fail; 90 91 INIT_LIST_HEAD(&workspace->list); 92 93 return &workspace->list; 94 fail: 95 lzo_free_workspace(&workspace->list); 96 return ERR_PTR(-ENOMEM); 97 } 98 99 static inline void write_compress_length(char *buf, size_t len) 100 { 101 __le32 dlen; 102 103 dlen = cpu_to_le32(len); 104 memcpy(buf, &dlen, LZO_LEN); 105 } 106 107 static inline size_t read_compress_length(const char *buf) 108 { 109 __le32 dlen; 110 111 memcpy(&dlen, buf, LZO_LEN); 112 return le32_to_cpu(dlen); 113 } 114 115 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 116 u64 start, struct page **pages, unsigned long *out_pages, 117 unsigned long *total_in, unsigned long *total_out) 118 { 119 struct workspace *workspace = list_entry(ws, struct workspace, list); 120 int ret = 0; 121 char *data_in; 122 char *cpage_out, *sizes_ptr; 123 int nr_pages = 0; 124 struct page *in_page = NULL; 125 struct page *out_page = NULL; 126 unsigned long bytes_left; 127 unsigned long len = *total_out; 128 unsigned long nr_dest_pages = *out_pages; 129 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 130 size_t in_len; 131 size_t out_len; 132 char *buf; 133 unsigned long tot_in = 0; 134 unsigned long tot_out = 0; 135 unsigned long pg_bytes_left; 136 unsigned long out_offset; 137 unsigned long bytes; 138 139 *out_pages = 0; 140 *total_out = 0; 141 *total_in = 0; 142 143 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 144 data_in = page_address(in_page); 145 146 /* 147 * store the size of all chunks of compressed data in 148 * the first 4 bytes 149 */ 150 out_page = alloc_page(GFP_NOFS); 151 if (out_page == NULL) { 152 ret = -ENOMEM; 153 goto out; 154 } 155 cpage_out = page_address(out_page); 156 out_offset = LZO_LEN; 157 tot_out = LZO_LEN; 158 pages[0] = out_page; 159 nr_pages = 1; 160 pg_bytes_left = PAGE_SIZE - LZO_LEN; 161 162 /* compress at most one page of data each time */ 163 in_len = min(len, PAGE_SIZE); 164 while (tot_in < len) { 165 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 166 &out_len, workspace->mem); 167 if (ret != LZO_E_OK) { 168 pr_debug("BTRFS: lzo in loop returned %d\n", 169 ret); 170 ret = -EIO; 171 goto out; 172 } 173 174 /* store the size of this chunk of compressed data */ 175 write_compress_length(cpage_out + out_offset, out_len); 176 tot_out += LZO_LEN; 177 out_offset += LZO_LEN; 178 pg_bytes_left -= LZO_LEN; 179 180 tot_in += in_len; 181 tot_out += out_len; 182 183 /* copy bytes from the working buffer into the pages */ 184 buf = workspace->cbuf; 185 while (out_len) { 186 bytes = min_t(unsigned long, pg_bytes_left, out_len); 187 188 memcpy(cpage_out + out_offset, buf, bytes); 189 190 out_len -= bytes; 191 pg_bytes_left -= bytes; 192 buf += bytes; 193 out_offset += bytes; 194 195 /* 196 * we need another page for writing out. 197 * 198 * Note if there's less than 4 bytes left, we just 199 * skip to a new page. 200 */ 201 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 202 pg_bytes_left == 0) { 203 if (pg_bytes_left) { 204 memset(cpage_out + out_offset, 0, 205 pg_bytes_left); 206 tot_out += pg_bytes_left; 207 } 208 209 /* we're done, don't allocate new page */ 210 if (out_len == 0 && tot_in >= len) 211 break; 212 213 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); 220 if (out_page == NULL) { 221 ret = -ENOMEM; 222 goto out; 223 } 224 cpage_out = page_address(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 put_page(in_page); 247 248 start += PAGE_SIZE; 249 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 250 data_in = page_address(in_page); 251 in_len = min(bytes_left, PAGE_SIZE); 252 } 253 254 if (tot_out >= tot_in) { 255 ret = -E2BIG; 256 goto out; 257 } 258 259 /* store the size of all chunks of compressed data */ 260 sizes_ptr = page_address(pages[0]); 261 write_compress_length(sizes_ptr, tot_out); 262 263 ret = 0; 264 *total_out = tot_out; 265 *total_in = tot_in; 266 out: 267 *out_pages = nr_pages; 268 269 if (in_page) 270 put_page(in_page); 271 272 return ret; 273 } 274 275 /* 276 * Copy the compressed segment payload into @dest. 277 * 278 * For the payload there will be no padding, just need to do page switching. 279 */ 280 static void copy_compressed_segment(struct compressed_bio *cb, 281 char *dest, u32 len, u32 *cur_in) 282 { 283 u32 orig_in = *cur_in; 284 285 while (*cur_in < orig_in + len) { 286 struct page *cur_page; 287 u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in), 288 orig_in + len - *cur_in); 289 290 ASSERT(copy_len); 291 cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE]; 292 293 memcpy(dest + *cur_in - orig_in, 294 page_address(cur_page) + offset_in_page(*cur_in), 295 copy_len); 296 297 *cur_in += copy_len; 298 } 299 } 300 301 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 302 { 303 struct workspace *workspace = list_entry(ws, struct workspace, list); 304 const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb); 305 const u32 sectorsize = fs_info->sectorsize; 306 int ret; 307 /* Compressed data length, can be unaligned */ 308 u32 len_in; 309 /* Offset inside the compressed data */ 310 u32 cur_in = 0; 311 /* Bytes decompressed so far */ 312 u32 cur_out = 0; 313 314 len_in = read_compress_length(page_address(cb->compressed_pages[0])); 315 cur_in += LZO_LEN; 316 317 /* 318 * LZO header length check 319 * 320 * The total length should not exceed the maximum extent length, 321 * and all sectors should be used. 322 * If this happens, it means the compressed extent is corrupted. 323 */ 324 if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) || 325 round_up(len_in, sectorsize) < cb->compressed_len) { 326 btrfs_err(fs_info, 327 "invalid lzo header, lzo len %u compressed len %u", 328 len_in, cb->compressed_len); 329 return -EUCLEAN; 330 } 331 332 /* Go through each lzo segment */ 333 while (cur_in < len_in) { 334 struct page *cur_page; 335 /* Length of the compressed segment */ 336 u32 seg_len; 337 u32 sector_bytes_left; 338 size_t out_len = lzo1x_worst_compress(sectorsize); 339 340 /* 341 * We should always have enough space for one segment header 342 * inside current sector. 343 */ 344 ASSERT(cur_in / sectorsize == 345 (cur_in + LZO_LEN - 1) / sectorsize); 346 cur_page = cb->compressed_pages[cur_in / PAGE_SIZE]; 347 ASSERT(cur_page); 348 seg_len = read_compress_length(page_address(cur_page) + 349 offset_in_page(cur_in)); 350 cur_in += LZO_LEN; 351 352 /* Copy the compressed segment payload into workspace */ 353 copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in); 354 355 /* Decompress the data */ 356 ret = lzo1x_decompress_safe(workspace->cbuf, seg_len, 357 workspace->buf, &out_len); 358 if (ret != LZO_E_OK) { 359 btrfs_err(fs_info, "failed to decompress"); 360 ret = -EIO; 361 goto out; 362 } 363 364 /* Copy the data into inode pages */ 365 ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out); 366 cur_out += out_len; 367 368 /* All data read, exit */ 369 if (ret == 0) 370 goto out; 371 ret = 0; 372 373 /* Check if the sector has enough space for a segment header */ 374 sector_bytes_left = sectorsize - (cur_in % sectorsize); 375 if (sector_bytes_left >= LZO_LEN) 376 continue; 377 378 /* Skip the padding zeros */ 379 cur_in += sector_bytes_left; 380 } 381 out: 382 if (!ret) 383 zero_fill_bio(cb->orig_bio); 384 return ret; 385 } 386 387 int lzo_decompress(struct list_head *ws, unsigned char *data_in, 388 struct page *dest_page, unsigned long start_byte, size_t srclen, 389 size_t destlen) 390 { 391 struct workspace *workspace = list_entry(ws, struct workspace, list); 392 size_t in_len; 393 size_t out_len; 394 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); 395 int ret = 0; 396 char *kaddr; 397 unsigned long bytes; 398 399 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2) 400 return -EUCLEAN; 401 402 in_len = read_compress_length(data_in); 403 if (in_len != srclen) 404 return -EUCLEAN; 405 data_in += LZO_LEN; 406 407 in_len = read_compress_length(data_in); 408 if (in_len != srclen - LZO_LEN * 2) { 409 ret = -EUCLEAN; 410 goto out; 411 } 412 data_in += LZO_LEN; 413 414 out_len = PAGE_SIZE; 415 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 416 if (ret != LZO_E_OK) { 417 pr_warn("BTRFS: decompress failed!\n"); 418 ret = -EIO; 419 goto out; 420 } 421 422 if (out_len < start_byte) { 423 ret = -EIO; 424 goto out; 425 } 426 427 /* 428 * the caller is already checking against PAGE_SIZE, but lets 429 * move this check closer to the memcpy/memset 430 */ 431 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 432 bytes = min_t(unsigned long, destlen, out_len - start_byte); 433 434 kaddr = page_address(dest_page); 435 memcpy(kaddr, workspace->buf + start_byte, bytes); 436 437 /* 438 * btrfs_getblock is doing a zero on the tail of the page too, 439 * but this will cover anything missing from the decompressed 440 * data. 441 */ 442 if (bytes < destlen) 443 memset(kaddr+bytes, 0, destlen-bytes); 444 out: 445 return ret; 446 } 447 448 const struct btrfs_compress_op btrfs_lzo_compress = { 449 .workspace_manager = &wsm, 450 .max_level = 1, 451 .default_level = 1, 452 }; 453