1 /* 2 * Copyright (C) 2008 Oracle. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19 #include <linux/kernel.h> 20 #include <linux/slab.h> 21 #include <linux/vmalloc.h> 22 #include <linux/init.h> 23 #include <linux/err.h> 24 #include <linux/sched.h> 25 #include <linux/pagemap.h> 26 #include <linux/bio.h> 27 #include <linux/lzo.h> 28 #include "compression.h" 29 30 #define LZO_LEN 4 31 32 struct workspace { 33 void *mem; 34 void *buf; /* where decompressed data goes */ 35 void *cbuf; /* where compressed data goes */ 36 struct list_head list; 37 }; 38 39 static void lzo_free_workspace(struct list_head *ws) 40 { 41 struct workspace *workspace = list_entry(ws, struct workspace, list); 42 43 vfree(workspace->buf); 44 vfree(workspace->cbuf); 45 vfree(workspace->mem); 46 kfree(workspace); 47 } 48 49 static struct list_head *lzo_alloc_workspace(void) 50 { 51 struct workspace *workspace; 52 53 workspace = kzalloc(sizeof(*workspace), GFP_NOFS); 54 if (!workspace) 55 return ERR_PTR(-ENOMEM); 56 57 workspace->mem = vmalloc(LZO1X_MEM_COMPRESS); 58 workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE)); 59 workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_SIZE)); 60 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 61 goto fail; 62 63 INIT_LIST_HEAD(&workspace->list); 64 65 return &workspace->list; 66 fail: 67 lzo_free_workspace(&workspace->list); 68 return ERR_PTR(-ENOMEM); 69 } 70 71 static inline void write_compress_length(char *buf, size_t len) 72 { 73 __le32 dlen; 74 75 dlen = cpu_to_le32(len); 76 memcpy(buf, &dlen, LZO_LEN); 77 } 78 79 static inline size_t read_compress_length(const char *buf) 80 { 81 __le32 dlen; 82 83 memcpy(&dlen, buf, LZO_LEN); 84 return le32_to_cpu(dlen); 85 } 86 87 static int lzo_compress_pages(struct list_head *ws, 88 struct address_space *mapping, 89 u64 start, 90 struct page **pages, 91 unsigned long *out_pages, 92 unsigned long *total_in, 93 unsigned long *total_out) 94 { 95 struct workspace *workspace = list_entry(ws, struct workspace, list); 96 int ret = 0; 97 char *data_in; 98 char *cpage_out; 99 int nr_pages = 0; 100 struct page *in_page = NULL; 101 struct page *out_page = NULL; 102 unsigned long bytes_left; 103 unsigned long len = *total_out; 104 unsigned long nr_dest_pages = *out_pages; 105 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 106 size_t in_len; 107 size_t out_len; 108 char *buf; 109 unsigned long tot_in = 0; 110 unsigned long tot_out = 0; 111 unsigned long pg_bytes_left; 112 unsigned long out_offset; 113 unsigned long bytes; 114 115 *out_pages = 0; 116 *total_out = 0; 117 *total_in = 0; 118 119 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 120 data_in = kmap(in_page); 121 122 /* 123 * store the size of all chunks of compressed data in 124 * the first 4 bytes 125 */ 126 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 127 if (out_page == NULL) { 128 ret = -ENOMEM; 129 goto out; 130 } 131 cpage_out = kmap(out_page); 132 out_offset = LZO_LEN; 133 tot_out = LZO_LEN; 134 pages[0] = out_page; 135 nr_pages = 1; 136 pg_bytes_left = PAGE_SIZE - LZO_LEN; 137 138 /* compress at most one page of data each time */ 139 in_len = min(len, PAGE_SIZE); 140 while (tot_in < len) { 141 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 142 &out_len, workspace->mem); 143 if (ret != LZO_E_OK) { 144 pr_debug("BTRFS: deflate in loop returned %d\n", 145 ret); 146 ret = -EIO; 147 goto out; 148 } 149 150 /* store the size of this chunk of compressed data */ 151 write_compress_length(cpage_out + out_offset, out_len); 152 tot_out += LZO_LEN; 153 out_offset += LZO_LEN; 154 pg_bytes_left -= LZO_LEN; 155 156 tot_in += in_len; 157 tot_out += out_len; 158 159 /* copy bytes from the working buffer into the pages */ 160 buf = workspace->cbuf; 161 while (out_len) { 162 bytes = min_t(unsigned long, pg_bytes_left, out_len); 163 164 memcpy(cpage_out + out_offset, buf, bytes); 165 166 out_len -= bytes; 167 pg_bytes_left -= bytes; 168 buf += bytes; 169 out_offset += bytes; 170 171 /* 172 * we need another page for writing out. 173 * 174 * Note if there's less than 4 bytes left, we just 175 * skip to a new page. 176 */ 177 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 178 pg_bytes_left == 0) { 179 if (pg_bytes_left) { 180 memset(cpage_out + out_offset, 0, 181 pg_bytes_left); 182 tot_out += pg_bytes_left; 183 } 184 185 /* we're done, don't allocate new page */ 186 if (out_len == 0 && tot_in >= len) 187 break; 188 189 kunmap(out_page); 190 if (nr_pages == nr_dest_pages) { 191 out_page = NULL; 192 ret = -E2BIG; 193 goto out; 194 } 195 196 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 197 if (out_page == NULL) { 198 ret = -ENOMEM; 199 goto out; 200 } 201 cpage_out = kmap(out_page); 202 pages[nr_pages++] = out_page; 203 204 pg_bytes_left = PAGE_SIZE; 205 out_offset = 0; 206 } 207 } 208 209 /* we're making it bigger, give up */ 210 if (tot_in > 8192 && tot_in < tot_out) { 211 ret = -E2BIG; 212 goto out; 213 } 214 215 /* we're all done */ 216 if (tot_in >= len) 217 break; 218 219 if (tot_out > max_out) 220 break; 221 222 bytes_left = len - tot_in; 223 kunmap(in_page); 224 put_page(in_page); 225 226 start += PAGE_SIZE; 227 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 228 data_in = kmap(in_page); 229 in_len = min(bytes_left, PAGE_SIZE); 230 } 231 232 if (tot_out > tot_in) 233 goto out; 234 235 /* store the size of all chunks of compressed data */ 236 cpage_out = kmap(pages[0]); 237 write_compress_length(cpage_out, tot_out); 238 239 kunmap(pages[0]); 240 241 ret = 0; 242 *total_out = tot_out; 243 *total_in = tot_in; 244 out: 245 *out_pages = nr_pages; 246 if (out_page) 247 kunmap(out_page); 248 249 if (in_page) { 250 kunmap(in_page); 251 put_page(in_page); 252 } 253 254 return ret; 255 } 256 257 static int lzo_decompress_bio(struct list_head *ws, 258 struct page **pages_in, 259 u64 disk_start, 260 struct bio *orig_bio, 261 size_t srclen) 262 { 263 struct workspace *workspace = list_entry(ws, struct workspace, list); 264 int ret = 0, ret2; 265 char *data_in; 266 unsigned long page_in_index = 0; 267 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 268 unsigned long buf_start; 269 unsigned long buf_offset = 0; 270 unsigned long bytes; 271 unsigned long working_bytes; 272 size_t in_len; 273 size_t out_len; 274 unsigned long in_offset; 275 unsigned long in_page_bytes_left; 276 unsigned long tot_in; 277 unsigned long tot_out; 278 unsigned long tot_len; 279 char *buf; 280 bool may_late_unmap, need_unmap; 281 282 data_in = kmap(pages_in[0]); 283 tot_len = read_compress_length(data_in); 284 285 tot_in = LZO_LEN; 286 in_offset = LZO_LEN; 287 tot_len = min_t(size_t, srclen, tot_len); 288 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 289 290 tot_out = 0; 291 292 while (tot_in < tot_len) { 293 in_len = read_compress_length(data_in + in_offset); 294 in_page_bytes_left -= LZO_LEN; 295 in_offset += LZO_LEN; 296 tot_in += LZO_LEN; 297 298 tot_in += in_len; 299 working_bytes = in_len; 300 may_late_unmap = need_unmap = false; 301 302 /* fast path: avoid using the working buffer */ 303 if (in_page_bytes_left >= in_len) { 304 buf = data_in + in_offset; 305 bytes = in_len; 306 may_late_unmap = true; 307 goto cont; 308 } 309 310 /* copy bytes from the pages into the working buffer */ 311 buf = workspace->cbuf; 312 buf_offset = 0; 313 while (working_bytes) { 314 bytes = min(working_bytes, in_page_bytes_left); 315 316 memcpy(buf + buf_offset, data_in + in_offset, bytes); 317 buf_offset += bytes; 318 cont: 319 working_bytes -= bytes; 320 in_page_bytes_left -= bytes; 321 in_offset += bytes; 322 323 /* check if we need to pick another page */ 324 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 325 || in_page_bytes_left == 0) { 326 tot_in += in_page_bytes_left; 327 328 if (working_bytes == 0 && tot_in >= tot_len) 329 break; 330 331 if (page_in_index + 1 >= total_pages_in) { 332 ret = -EIO; 333 goto done; 334 } 335 336 if (may_late_unmap) 337 need_unmap = true; 338 else 339 kunmap(pages_in[page_in_index]); 340 341 data_in = kmap(pages_in[++page_in_index]); 342 343 in_page_bytes_left = PAGE_SIZE; 344 in_offset = 0; 345 } 346 } 347 348 out_len = lzo1x_worst_compress(PAGE_SIZE); 349 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 350 &out_len); 351 if (need_unmap) 352 kunmap(pages_in[page_in_index - 1]); 353 if (ret != LZO_E_OK) { 354 pr_warn("BTRFS: decompress failed\n"); 355 ret = -EIO; 356 break; 357 } 358 359 buf_start = tot_out; 360 tot_out += out_len; 361 362 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 363 tot_out, disk_start, orig_bio); 364 if (ret2 == 0) 365 break; 366 } 367 done: 368 kunmap(pages_in[page_in_index]); 369 if (!ret) 370 zero_fill_bio(orig_bio); 371 return ret; 372 } 373 374 static int lzo_decompress(struct list_head *ws, unsigned char *data_in, 375 struct page *dest_page, 376 unsigned long start_byte, 377 size_t srclen, size_t destlen) 378 { 379 struct workspace *workspace = list_entry(ws, struct workspace, list); 380 size_t in_len; 381 size_t out_len; 382 size_t tot_len; 383 int ret = 0; 384 char *kaddr; 385 unsigned long bytes; 386 387 BUG_ON(srclen < LZO_LEN); 388 389 tot_len = read_compress_length(data_in); 390 data_in += LZO_LEN; 391 392 in_len = read_compress_length(data_in); 393 data_in += LZO_LEN; 394 395 out_len = PAGE_SIZE; 396 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 397 if (ret != LZO_E_OK) { 398 pr_warn("BTRFS: decompress failed!\n"); 399 ret = -EIO; 400 goto out; 401 } 402 403 if (out_len < start_byte) { 404 ret = -EIO; 405 goto out; 406 } 407 408 /* 409 * the caller is already checking against PAGE_SIZE, but lets 410 * move this check closer to the memcpy/memset 411 */ 412 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 413 bytes = min_t(unsigned long, destlen, out_len - start_byte); 414 415 kaddr = kmap_atomic(dest_page); 416 memcpy(kaddr, workspace->buf + start_byte, bytes); 417 418 /* 419 * btrfs_getblock is doing a zero on the tail of the page too, 420 * but this will cover anything missing from the decompressed 421 * data. 422 */ 423 if (bytes < destlen) 424 memset(kaddr+bytes, 0, destlen-bytes); 425 kunmap_atomic(kaddr); 426 out: 427 return ret; 428 } 429 430 const struct btrfs_compress_op btrfs_lzo_compress = { 431 .alloc_workspace = lzo_alloc_workspace, 432 .free_workspace = lzo_free_workspace, 433 .compress_pages = lzo_compress_pages, 434 .decompress_bio = lzo_decompress_bio, 435 .decompress = lzo_decompress, 436 }; 437