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 struct workspace { 21 void *mem; 22 void *buf; /* where decompressed data goes */ 23 void *cbuf; /* where compressed data goes */ 24 struct list_head list; 25 }; 26 27 static void lzo_free_workspace(struct list_head *ws) 28 { 29 struct workspace *workspace = list_entry(ws, struct workspace, list); 30 31 kvfree(workspace->buf); 32 kvfree(workspace->cbuf); 33 kvfree(workspace->mem); 34 kfree(workspace); 35 } 36 37 static struct list_head *lzo_alloc_workspace(void) 38 { 39 struct workspace *workspace; 40 41 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); 42 if (!workspace) 43 return ERR_PTR(-ENOMEM); 44 45 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); 46 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 47 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 48 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 49 goto fail; 50 51 INIT_LIST_HEAD(&workspace->list); 52 53 return &workspace->list; 54 fail: 55 lzo_free_workspace(&workspace->list); 56 return ERR_PTR(-ENOMEM); 57 } 58 59 static inline void write_compress_length(char *buf, size_t len) 60 { 61 __le32 dlen; 62 63 dlen = cpu_to_le32(len); 64 memcpy(buf, &dlen, LZO_LEN); 65 } 66 67 static inline size_t read_compress_length(const char *buf) 68 { 69 __le32 dlen; 70 71 memcpy(&dlen, buf, LZO_LEN); 72 return le32_to_cpu(dlen); 73 } 74 75 static int lzo_compress_pages(struct list_head *ws, 76 struct address_space *mapping, 77 u64 start, 78 struct page **pages, 79 unsigned long *out_pages, 80 unsigned long *total_in, 81 unsigned long *total_out) 82 { 83 struct workspace *workspace = list_entry(ws, struct workspace, list); 84 int ret = 0; 85 char *data_in; 86 char *cpage_out; 87 int nr_pages = 0; 88 struct page *in_page = NULL; 89 struct page *out_page = NULL; 90 unsigned long bytes_left; 91 unsigned long len = *total_out; 92 unsigned long nr_dest_pages = *out_pages; 93 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 94 size_t in_len; 95 size_t out_len; 96 char *buf; 97 unsigned long tot_in = 0; 98 unsigned long tot_out = 0; 99 unsigned long pg_bytes_left; 100 unsigned long out_offset; 101 unsigned long bytes; 102 103 *out_pages = 0; 104 *total_out = 0; 105 *total_in = 0; 106 107 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 108 data_in = kmap(in_page); 109 110 /* 111 * store the size of all chunks of compressed data in 112 * the first 4 bytes 113 */ 114 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 115 if (out_page == NULL) { 116 ret = -ENOMEM; 117 goto out; 118 } 119 cpage_out = kmap(out_page); 120 out_offset = LZO_LEN; 121 tot_out = LZO_LEN; 122 pages[0] = out_page; 123 nr_pages = 1; 124 pg_bytes_left = PAGE_SIZE - LZO_LEN; 125 126 /* compress at most one page of data each time */ 127 in_len = min(len, PAGE_SIZE); 128 while (tot_in < len) { 129 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 130 &out_len, workspace->mem); 131 if (ret != LZO_E_OK) { 132 pr_debug("BTRFS: lzo in loop returned %d\n", 133 ret); 134 ret = -EIO; 135 goto out; 136 } 137 138 /* store the size of this chunk of compressed data */ 139 write_compress_length(cpage_out + out_offset, out_len); 140 tot_out += LZO_LEN; 141 out_offset += LZO_LEN; 142 pg_bytes_left -= LZO_LEN; 143 144 tot_in += in_len; 145 tot_out += out_len; 146 147 /* copy bytes from the working buffer into the pages */ 148 buf = workspace->cbuf; 149 while (out_len) { 150 bytes = min_t(unsigned long, pg_bytes_left, out_len); 151 152 memcpy(cpage_out + out_offset, buf, bytes); 153 154 out_len -= bytes; 155 pg_bytes_left -= bytes; 156 buf += bytes; 157 out_offset += bytes; 158 159 /* 160 * we need another page for writing out. 161 * 162 * Note if there's less than 4 bytes left, we just 163 * skip to a new page. 164 */ 165 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 166 pg_bytes_left == 0) { 167 if (pg_bytes_left) { 168 memset(cpage_out + out_offset, 0, 169 pg_bytes_left); 170 tot_out += pg_bytes_left; 171 } 172 173 /* we're done, don't allocate new page */ 174 if (out_len == 0 && tot_in >= len) 175 break; 176 177 kunmap(out_page); 178 if (nr_pages == nr_dest_pages) { 179 out_page = NULL; 180 ret = -E2BIG; 181 goto out; 182 } 183 184 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 185 if (out_page == NULL) { 186 ret = -ENOMEM; 187 goto out; 188 } 189 cpage_out = kmap(out_page); 190 pages[nr_pages++] = out_page; 191 192 pg_bytes_left = PAGE_SIZE; 193 out_offset = 0; 194 } 195 } 196 197 /* we're making it bigger, give up */ 198 if (tot_in > 8192 && tot_in < tot_out) { 199 ret = -E2BIG; 200 goto out; 201 } 202 203 /* we're all done */ 204 if (tot_in >= len) 205 break; 206 207 if (tot_out > max_out) 208 break; 209 210 bytes_left = len - tot_in; 211 kunmap(in_page); 212 put_page(in_page); 213 214 start += PAGE_SIZE; 215 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 216 data_in = kmap(in_page); 217 in_len = min(bytes_left, PAGE_SIZE); 218 } 219 220 if (tot_out >= tot_in) { 221 ret = -E2BIG; 222 goto out; 223 } 224 225 /* store the size of all chunks of compressed data */ 226 cpage_out = kmap(pages[0]); 227 write_compress_length(cpage_out, tot_out); 228 229 kunmap(pages[0]); 230 231 ret = 0; 232 *total_out = tot_out; 233 *total_in = tot_in; 234 out: 235 *out_pages = nr_pages; 236 if (out_page) 237 kunmap(out_page); 238 239 if (in_page) { 240 kunmap(in_page); 241 put_page(in_page); 242 } 243 244 return ret; 245 } 246 247 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 248 { 249 struct workspace *workspace = list_entry(ws, struct workspace, list); 250 int ret = 0, ret2; 251 char *data_in; 252 unsigned long page_in_index = 0; 253 size_t srclen = cb->compressed_len; 254 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 255 unsigned long buf_start; 256 unsigned long buf_offset = 0; 257 unsigned long bytes; 258 unsigned long working_bytes; 259 size_t in_len; 260 size_t out_len; 261 unsigned long in_offset; 262 unsigned long in_page_bytes_left; 263 unsigned long tot_in; 264 unsigned long tot_out; 265 unsigned long tot_len; 266 char *buf; 267 bool may_late_unmap, need_unmap; 268 struct page **pages_in = cb->compressed_pages; 269 u64 disk_start = cb->start; 270 struct bio *orig_bio = cb->orig_bio; 271 272 data_in = kmap(pages_in[0]); 273 tot_len = read_compress_length(data_in); 274 275 tot_in = LZO_LEN; 276 in_offset = LZO_LEN; 277 tot_len = min_t(size_t, srclen, tot_len); 278 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 279 280 tot_out = 0; 281 282 while (tot_in < tot_len) { 283 in_len = read_compress_length(data_in + in_offset); 284 in_page_bytes_left -= LZO_LEN; 285 in_offset += LZO_LEN; 286 tot_in += LZO_LEN; 287 288 tot_in += in_len; 289 working_bytes = in_len; 290 may_late_unmap = need_unmap = false; 291 292 /* fast path: avoid using the working buffer */ 293 if (in_page_bytes_left >= in_len) { 294 buf = data_in + in_offset; 295 bytes = in_len; 296 may_late_unmap = true; 297 goto cont; 298 } 299 300 /* copy bytes from the pages into the working buffer */ 301 buf = workspace->cbuf; 302 buf_offset = 0; 303 while (working_bytes) { 304 bytes = min(working_bytes, in_page_bytes_left); 305 306 memcpy(buf + buf_offset, data_in + in_offset, bytes); 307 buf_offset += bytes; 308 cont: 309 working_bytes -= bytes; 310 in_page_bytes_left -= bytes; 311 in_offset += bytes; 312 313 /* check if we need to pick another page */ 314 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 315 || in_page_bytes_left == 0) { 316 tot_in += in_page_bytes_left; 317 318 if (working_bytes == 0 && tot_in >= tot_len) 319 break; 320 321 if (page_in_index + 1 >= total_pages_in) { 322 ret = -EIO; 323 goto done; 324 } 325 326 if (may_late_unmap) 327 need_unmap = true; 328 else 329 kunmap(pages_in[page_in_index]); 330 331 data_in = kmap(pages_in[++page_in_index]); 332 333 in_page_bytes_left = PAGE_SIZE; 334 in_offset = 0; 335 } 336 } 337 338 out_len = lzo1x_worst_compress(PAGE_SIZE); 339 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 340 &out_len); 341 if (need_unmap) 342 kunmap(pages_in[page_in_index - 1]); 343 if (ret != LZO_E_OK) { 344 pr_warn("BTRFS: decompress failed\n"); 345 ret = -EIO; 346 break; 347 } 348 349 buf_start = tot_out; 350 tot_out += out_len; 351 352 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 353 tot_out, disk_start, orig_bio); 354 if (ret2 == 0) 355 break; 356 } 357 done: 358 kunmap(pages_in[page_in_index]); 359 if (!ret) 360 zero_fill_bio(orig_bio); 361 return ret; 362 } 363 364 static int lzo_decompress(struct list_head *ws, unsigned char *data_in, 365 struct page *dest_page, 366 unsigned long start_byte, 367 size_t srclen, size_t destlen) 368 { 369 struct workspace *workspace = list_entry(ws, struct workspace, list); 370 size_t in_len; 371 size_t out_len; 372 int ret = 0; 373 char *kaddr; 374 unsigned long bytes; 375 376 BUG_ON(srclen < LZO_LEN); 377 378 data_in += LZO_LEN; 379 380 in_len = read_compress_length(data_in); 381 data_in += LZO_LEN; 382 383 out_len = PAGE_SIZE; 384 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 385 if (ret != LZO_E_OK) { 386 pr_warn("BTRFS: decompress failed!\n"); 387 ret = -EIO; 388 goto out; 389 } 390 391 if (out_len < start_byte) { 392 ret = -EIO; 393 goto out; 394 } 395 396 /* 397 * the caller is already checking against PAGE_SIZE, but lets 398 * move this check closer to the memcpy/memset 399 */ 400 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 401 bytes = min_t(unsigned long, destlen, out_len - start_byte); 402 403 kaddr = kmap_atomic(dest_page); 404 memcpy(kaddr, workspace->buf + start_byte, bytes); 405 406 /* 407 * btrfs_getblock is doing a zero on the tail of the page too, 408 * but this will cover anything missing from the decompressed 409 * data. 410 */ 411 if (bytes < destlen) 412 memset(kaddr+bytes, 0, destlen-bytes); 413 kunmap_atomic(kaddr); 414 out: 415 return ret; 416 } 417 418 static void lzo_set_level(struct list_head *ws, unsigned int type) 419 { 420 } 421 422 const struct btrfs_compress_op btrfs_lzo_compress = { 423 .alloc_workspace = lzo_alloc_workspace, 424 .free_workspace = lzo_free_workspace, 425 .compress_pages = lzo_compress_pages, 426 .decompress_bio = lzo_decompress_bio, 427 .decompress = lzo_decompress, 428 .set_level = lzo_set_level, 429 }; 430