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/mm.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 <linux/refcount.h> 29 #include "compression.h" 30 31 #define LZO_LEN 4 32 33 struct workspace { 34 void *mem; 35 void *buf; /* where decompressed data goes */ 36 void *cbuf; /* where compressed data goes */ 37 struct list_head list; 38 }; 39 40 static void lzo_free_workspace(struct list_head *ws) 41 { 42 struct workspace *workspace = list_entry(ws, struct workspace, list); 43 44 kvfree(workspace->buf); 45 kvfree(workspace->cbuf); 46 kvfree(workspace->mem); 47 kfree(workspace); 48 } 49 50 static struct list_head *lzo_alloc_workspace(void) 51 { 52 struct workspace *workspace; 53 54 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); 55 if (!workspace) 56 return ERR_PTR(-ENOMEM); 57 58 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); 59 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 60 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); 61 if (!workspace->mem || !workspace->buf || !workspace->cbuf) 62 goto fail; 63 64 INIT_LIST_HEAD(&workspace->list); 65 66 return &workspace->list; 67 fail: 68 lzo_free_workspace(&workspace->list); 69 return ERR_PTR(-ENOMEM); 70 } 71 72 static inline void write_compress_length(char *buf, size_t len) 73 { 74 __le32 dlen; 75 76 dlen = cpu_to_le32(len); 77 memcpy(buf, &dlen, LZO_LEN); 78 } 79 80 static inline size_t read_compress_length(const char *buf) 81 { 82 __le32 dlen; 83 84 memcpy(&dlen, buf, LZO_LEN); 85 return le32_to_cpu(dlen); 86 } 87 88 static int lzo_compress_pages(struct list_head *ws, 89 struct address_space *mapping, 90 u64 start, 91 struct page **pages, 92 unsigned long *out_pages, 93 unsigned long *total_in, 94 unsigned long *total_out) 95 { 96 struct workspace *workspace = list_entry(ws, struct workspace, list); 97 int ret = 0; 98 char *data_in; 99 char *cpage_out; 100 int nr_pages = 0; 101 struct page *in_page = NULL; 102 struct page *out_page = NULL; 103 unsigned long bytes_left; 104 unsigned long len = *total_out; 105 unsigned long nr_dest_pages = *out_pages; 106 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 107 size_t in_len; 108 size_t out_len; 109 char *buf; 110 unsigned long tot_in = 0; 111 unsigned long tot_out = 0; 112 unsigned long pg_bytes_left; 113 unsigned long out_offset; 114 unsigned long bytes; 115 116 *out_pages = 0; 117 *total_out = 0; 118 *total_in = 0; 119 120 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 121 data_in = kmap(in_page); 122 123 /* 124 * store the size of all chunks of compressed data in 125 * the first 4 bytes 126 */ 127 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 128 if (out_page == NULL) { 129 ret = -ENOMEM; 130 goto out; 131 } 132 cpage_out = kmap(out_page); 133 out_offset = LZO_LEN; 134 tot_out = LZO_LEN; 135 pages[0] = out_page; 136 nr_pages = 1; 137 pg_bytes_left = PAGE_SIZE - LZO_LEN; 138 139 /* compress at most one page of data each time */ 140 in_len = min(len, PAGE_SIZE); 141 while (tot_in < len) { 142 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, 143 &out_len, workspace->mem); 144 if (ret != LZO_E_OK) { 145 pr_debug("BTRFS: lzo in loop returned %d\n", 146 ret); 147 ret = -EIO; 148 goto out; 149 } 150 151 /* store the size of this chunk of compressed data */ 152 write_compress_length(cpage_out + out_offset, out_len); 153 tot_out += LZO_LEN; 154 out_offset += LZO_LEN; 155 pg_bytes_left -= LZO_LEN; 156 157 tot_in += in_len; 158 tot_out += out_len; 159 160 /* copy bytes from the working buffer into the pages */ 161 buf = workspace->cbuf; 162 while (out_len) { 163 bytes = min_t(unsigned long, pg_bytes_left, out_len); 164 165 memcpy(cpage_out + out_offset, buf, bytes); 166 167 out_len -= bytes; 168 pg_bytes_left -= bytes; 169 buf += bytes; 170 out_offset += bytes; 171 172 /* 173 * we need another page for writing out. 174 * 175 * Note if there's less than 4 bytes left, we just 176 * skip to a new page. 177 */ 178 if ((out_len == 0 && pg_bytes_left < LZO_LEN) || 179 pg_bytes_left == 0) { 180 if (pg_bytes_left) { 181 memset(cpage_out + out_offset, 0, 182 pg_bytes_left); 183 tot_out += pg_bytes_left; 184 } 185 186 /* we're done, don't allocate new page */ 187 if (out_len == 0 && tot_in >= len) 188 break; 189 190 kunmap(out_page); 191 if (nr_pages == nr_dest_pages) { 192 out_page = NULL; 193 ret = -E2BIG; 194 goto out; 195 } 196 197 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 198 if (out_page == NULL) { 199 ret = -ENOMEM; 200 goto out; 201 } 202 cpage_out = kmap(out_page); 203 pages[nr_pages++] = out_page; 204 205 pg_bytes_left = PAGE_SIZE; 206 out_offset = 0; 207 } 208 } 209 210 /* we're making it bigger, give up */ 211 if (tot_in > 8192 && tot_in < tot_out) { 212 ret = -E2BIG; 213 goto out; 214 } 215 216 /* we're all done */ 217 if (tot_in >= len) 218 break; 219 220 if (tot_out > max_out) 221 break; 222 223 bytes_left = len - tot_in; 224 kunmap(in_page); 225 put_page(in_page); 226 227 start += PAGE_SIZE; 228 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 229 data_in = kmap(in_page); 230 in_len = min(bytes_left, PAGE_SIZE); 231 } 232 233 if (tot_out >= tot_in) { 234 ret = -E2BIG; 235 goto out; 236 } 237 238 /* store the size of all chunks of compressed data */ 239 cpage_out = kmap(pages[0]); 240 write_compress_length(cpage_out, tot_out); 241 242 kunmap(pages[0]); 243 244 ret = 0; 245 *total_out = tot_out; 246 *total_in = tot_in; 247 out: 248 *out_pages = nr_pages; 249 if (out_page) 250 kunmap(out_page); 251 252 if (in_page) { 253 kunmap(in_page); 254 put_page(in_page); 255 } 256 257 return ret; 258 } 259 260 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 261 { 262 struct workspace *workspace = list_entry(ws, struct workspace, list); 263 int ret = 0, ret2; 264 char *data_in; 265 unsigned long page_in_index = 0; 266 size_t srclen = cb->compressed_len; 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 struct page **pages_in = cb->compressed_pages; 282 u64 disk_start = cb->start; 283 struct bio *orig_bio = cb->orig_bio; 284 285 data_in = kmap(pages_in[0]); 286 tot_len = read_compress_length(data_in); 287 288 tot_in = LZO_LEN; 289 in_offset = LZO_LEN; 290 tot_len = min_t(size_t, srclen, tot_len); 291 in_page_bytes_left = PAGE_SIZE - LZO_LEN; 292 293 tot_out = 0; 294 295 while (tot_in < tot_len) { 296 in_len = read_compress_length(data_in + in_offset); 297 in_page_bytes_left -= LZO_LEN; 298 in_offset += LZO_LEN; 299 tot_in += LZO_LEN; 300 301 tot_in += in_len; 302 working_bytes = in_len; 303 may_late_unmap = need_unmap = false; 304 305 /* fast path: avoid using the working buffer */ 306 if (in_page_bytes_left >= in_len) { 307 buf = data_in + in_offset; 308 bytes = in_len; 309 may_late_unmap = true; 310 goto cont; 311 } 312 313 /* copy bytes from the pages into the working buffer */ 314 buf = workspace->cbuf; 315 buf_offset = 0; 316 while (working_bytes) { 317 bytes = min(working_bytes, in_page_bytes_left); 318 319 memcpy(buf + buf_offset, data_in + in_offset, bytes); 320 buf_offset += bytes; 321 cont: 322 working_bytes -= bytes; 323 in_page_bytes_left -= bytes; 324 in_offset += bytes; 325 326 /* check if we need to pick another page */ 327 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) 328 || in_page_bytes_left == 0) { 329 tot_in += in_page_bytes_left; 330 331 if (working_bytes == 0 && tot_in >= tot_len) 332 break; 333 334 if (page_in_index + 1 >= total_pages_in) { 335 ret = -EIO; 336 goto done; 337 } 338 339 if (may_late_unmap) 340 need_unmap = true; 341 else 342 kunmap(pages_in[page_in_index]); 343 344 data_in = kmap(pages_in[++page_in_index]); 345 346 in_page_bytes_left = PAGE_SIZE; 347 in_offset = 0; 348 } 349 } 350 351 out_len = lzo1x_worst_compress(PAGE_SIZE); 352 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, 353 &out_len); 354 if (need_unmap) 355 kunmap(pages_in[page_in_index - 1]); 356 if (ret != LZO_E_OK) { 357 pr_warn("BTRFS: decompress failed\n"); 358 ret = -EIO; 359 break; 360 } 361 362 buf_start = tot_out; 363 tot_out += out_len; 364 365 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 366 tot_out, disk_start, orig_bio); 367 if (ret2 == 0) 368 break; 369 } 370 done: 371 kunmap(pages_in[page_in_index]); 372 if (!ret) 373 zero_fill_bio(orig_bio); 374 return ret; 375 } 376 377 static int lzo_decompress(struct list_head *ws, unsigned char *data_in, 378 struct page *dest_page, 379 unsigned long start_byte, 380 size_t srclen, size_t destlen) 381 { 382 struct workspace *workspace = list_entry(ws, struct workspace, list); 383 size_t in_len; 384 size_t out_len; 385 size_t tot_len; 386 int ret = 0; 387 char *kaddr; 388 unsigned long bytes; 389 390 BUG_ON(srclen < LZO_LEN); 391 392 tot_len = read_compress_length(data_in); 393 data_in += LZO_LEN; 394 395 in_len = read_compress_length(data_in); 396 data_in += LZO_LEN; 397 398 out_len = PAGE_SIZE; 399 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); 400 if (ret != LZO_E_OK) { 401 pr_warn("BTRFS: decompress failed!\n"); 402 ret = -EIO; 403 goto out; 404 } 405 406 if (out_len < start_byte) { 407 ret = -EIO; 408 goto out; 409 } 410 411 /* 412 * the caller is already checking against PAGE_SIZE, but lets 413 * move this check closer to the memcpy/memset 414 */ 415 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 416 bytes = min_t(unsigned long, destlen, out_len - start_byte); 417 418 kaddr = kmap_atomic(dest_page); 419 memcpy(kaddr, workspace->buf + start_byte, bytes); 420 421 /* 422 * btrfs_getblock is doing a zero on the tail of the page too, 423 * but this will cover anything missing from the decompressed 424 * data. 425 */ 426 if (bytes < destlen) 427 memset(kaddr+bytes, 0, destlen-bytes); 428 kunmap_atomic(kaddr); 429 out: 430 return ret; 431 } 432 433 const struct btrfs_compress_op btrfs_lzo_compress = { 434 .alloc_workspace = lzo_alloc_workspace, 435 .free_workspace = lzo_free_workspace, 436 .compress_pages = lzo_compress_pages, 437 .decompress_bio = lzo_decompress_bio, 438 .decompress = lzo_decompress, 439 }; 440