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_CACHE_SIZE)); 59 workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_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(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, unsigned long len, 90 struct page **pages, 91 unsigned long nr_dest_pages, 92 unsigned long *out_pages, 93 unsigned long *total_in, 94 unsigned long *total_out, 95 unsigned long max_out) 96 { 97 struct workspace *workspace = list_entry(ws, struct workspace, list); 98 int ret = 0; 99 char *data_in; 100 char *cpage_out; 101 int nr_pages = 0; 102 struct page *in_page = NULL; 103 struct page *out_page = NULL; 104 unsigned long bytes_left; 105 106 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_CACHE_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_CACHE_SIZE - LZO_LEN; 137 138 /* compress at most one page of data each time */ 139 in_len = min(len, PAGE_CACHE_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 printk(KERN_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_CACHE_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 page_cache_release(in_page); 225 226 start += PAGE_CACHE_SIZE; 227 in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT); 228 data_in = kmap(in_page); 229 in_len = min(bytes_left, PAGE_CACHE_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 page_cache_release(in_page); 252 } 253 254 return ret; 255 } 256 257 static int lzo_decompress_biovec(struct list_head *ws, 258 struct page **pages_in, 259 u64 disk_start, 260 struct bio_vec *bvec, 261 int vcnt, 262 size_t srclen) 263 { 264 struct workspace *workspace = list_entry(ws, struct workspace, list); 265 int ret = 0, ret2; 266 char *data_in; 267 unsigned long page_in_index = 0; 268 unsigned long page_out_index = 0; 269 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE); 270 unsigned long buf_start; 271 unsigned long buf_offset = 0; 272 unsigned long bytes; 273 unsigned long working_bytes; 274 unsigned long pg_offset; 275 276 size_t in_len; 277 size_t out_len; 278 unsigned long in_offset; 279 unsigned long in_page_bytes_left; 280 unsigned long tot_in; 281 unsigned long tot_out; 282 unsigned long tot_len; 283 char *buf; 284 bool may_late_unmap, need_unmap; 285 286 data_in = kmap(pages_in[0]); 287 tot_len = read_compress_length(data_in); 288 289 tot_in = LZO_LEN; 290 in_offset = LZO_LEN; 291 tot_len = min_t(size_t, srclen, tot_len); 292 in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN; 293 294 tot_out = 0; 295 pg_offset = 0; 296 297 while (tot_in < tot_len) { 298 in_len = read_compress_length(data_in + in_offset); 299 in_page_bytes_left -= LZO_LEN; 300 in_offset += LZO_LEN; 301 tot_in += LZO_LEN; 302 303 tot_in += in_len; 304 working_bytes = in_len; 305 may_late_unmap = need_unmap = false; 306 307 /* fast path: avoid using the working buffer */ 308 if (in_page_bytes_left >= in_len) { 309 buf = data_in + in_offset; 310 bytes = in_len; 311 may_late_unmap = true; 312 goto cont; 313 } 314 315 /* copy bytes from the pages into the working buffer */ 316 buf = workspace->cbuf; 317 buf_offset = 0; 318 while (working_bytes) { 319 bytes = min(working_bytes, in_page_bytes_left); 320 321 memcpy(buf + buf_offset, data_in + in_offset, bytes); 322 buf_offset += bytes; 323 cont: 324 working_bytes -= bytes; 325 in_page_bytes_left -= bytes; 326 in_offset += bytes; 327 328 /* check if we need to pick another page */ 329 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 330 || in_page_bytes_left == 0) { 331 tot_in += in_page_bytes_left; 332 333 if (working_bytes == 0 && tot_in >= tot_len) 334 break; 335 336 if (page_in_index + 1 >= total_pages_in) { 337 ret = -EIO; 338 goto done; 339 } 340 341 if (may_late_unmap) 342 need_unmap = true; 343 else 344 kunmap(pages_in[page_in_index]); 345 346 data_in = kmap(pages_in[++page_in_index]); 347 348 in_page_bytes_left = PAGE_CACHE_SIZE; 349 in_offset = 0; 350 } 351 } 352 353 out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE); 354 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 355 &out_len); 356 if (need_unmap) 357 kunmap(pages_in[page_in_index - 1]); 358 if (ret != LZO_E_OK) { 359 printk(KERN_WARNING "BTRFS: decompress failed\n"); 360 ret = -EIO; 361 break; 362 } 363 364 buf_start = tot_out; 365 tot_out += out_len; 366 367 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 368 tot_out, disk_start, 369 bvec, vcnt, 370 &page_out_index, &pg_offset); 371 if (ret2 == 0) 372 break; 373 } 374 done: 375 kunmap(pages_in[page_in_index]); 376 if (!ret) 377 btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset); 378 return ret; 379 } 380 381 static int lzo_decompress(struct list_head *ws, unsigned char *data_in, 382 struct page *dest_page, 383 unsigned long start_byte, 384 size_t srclen, size_t destlen) 385 { 386 struct workspace *workspace = list_entry(ws, struct workspace, list); 387 size_t in_len; 388 size_t out_len; 389 size_t tot_len; 390 int ret = 0; 391 char *kaddr; 392 unsigned long bytes; 393 394 BUG_ON(srclen < LZO_LEN); 395 396 tot_len = read_compress_length(data_in); 397 data_in += LZO_LEN; 398 399 in_len = read_compress_length(data_in); 400 data_in += LZO_LEN; 401 402 out_len = PAGE_CACHE_SIZE; 403 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 404 if (ret != LZO_E_OK) { 405 printk(KERN_WARNING "BTRFS: decompress failed!\n"); 406 ret = -EIO; 407 goto out; 408 } 409 410 if (out_len < start_byte) { 411 ret = -EIO; 412 goto out; 413 } 414 415 /* 416 * the caller is already checking against PAGE_SIZE, but lets 417 * move this check closer to the memcpy/memset 418 */ 419 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 420 bytes = min_t(unsigned long, destlen, out_len - start_byte); 421 422 kaddr = kmap_atomic(dest_page); 423 memcpy(kaddr, workspace->buf + start_byte, bytes); 424 425 /* 426 * btrfs_getblock is doing a zero on the tail of the page too, 427 * but this will cover anything missing from the decompressed 428 * data. 429 */ 430 if (bytes < destlen) 431 memset(kaddr+bytes, 0, destlen-bytes); 432 kunmap_atomic(kaddr); 433 out: 434 return ret; 435 } 436 437 struct btrfs_compress_op btrfs_lzo_compress = { 438 .alloc_workspace = lzo_alloc_workspace, 439 .free_workspace = lzo_free_workspace, 440 .compress_pages = lzo_compress_pages, 441 .decompress_biovec = lzo_decompress_biovec, 442 .decompress = lzo_decompress, 443 }; 444