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 * Based on jffs2 zlib code: 19 * Copyright © 2001-2007 Red Hat, Inc. 20 * Created by David Woodhouse <dwmw2@infradead.org> 21 */ 22 23 #include <linux/kernel.h> 24 #include <linux/slab.h> 25 #include <linux/zlib.h> 26 #include <linux/zutil.h> 27 #include <linux/vmalloc.h> 28 #include <linux/init.h> 29 #include <linux/err.h> 30 #include <linux/sched.h> 31 #include <linux/pagemap.h> 32 #include <linux/bio.h> 33 #include "compression.h" 34 35 struct workspace { 36 z_stream strm; 37 char *buf; 38 struct list_head list; 39 }; 40 41 static void zlib_free_workspace(struct list_head *ws) 42 { 43 struct workspace *workspace = list_entry(ws, struct workspace, list); 44 45 vfree(workspace->strm.workspace); 46 kfree(workspace->buf); 47 kfree(workspace); 48 } 49 50 static struct list_head *zlib_alloc_workspace(void) 51 { 52 struct workspace *workspace; 53 int workspacesize; 54 55 workspace = kzalloc(sizeof(*workspace), GFP_NOFS); 56 if (!workspace) 57 return ERR_PTR(-ENOMEM); 58 59 workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL), 60 zlib_inflate_workspacesize()); 61 workspace->strm.workspace = vmalloc(workspacesize); 62 workspace->buf = kmalloc(PAGE_SIZE, GFP_NOFS); 63 if (!workspace->strm.workspace || !workspace->buf) 64 goto fail; 65 66 INIT_LIST_HEAD(&workspace->list); 67 68 return &workspace->list; 69 fail: 70 zlib_free_workspace(&workspace->list); 71 return ERR_PTR(-ENOMEM); 72 } 73 74 static int zlib_compress_pages(struct list_head *ws, 75 struct address_space *mapping, 76 u64 start, 77 struct page **pages, 78 unsigned long *out_pages, 79 unsigned long *total_in, 80 unsigned long *total_out) 81 { 82 struct workspace *workspace = list_entry(ws, struct workspace, list); 83 int ret; 84 char *data_in; 85 char *cpage_out; 86 int nr_pages = 0; 87 struct page *in_page = NULL; 88 struct page *out_page = NULL; 89 unsigned long bytes_left; 90 unsigned long len = *total_out; 91 unsigned long nr_dest_pages = *out_pages; 92 const unsigned long max_out = nr_dest_pages * PAGE_SIZE; 93 94 *out_pages = 0; 95 *total_out = 0; 96 *total_in = 0; 97 98 if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) { 99 pr_warn("BTRFS: deflateInit failed\n"); 100 ret = -EIO; 101 goto out; 102 } 103 104 workspace->strm.total_in = 0; 105 workspace->strm.total_out = 0; 106 107 in_page = find_get_page(mapping, start >> PAGE_SHIFT); 108 data_in = kmap(in_page); 109 110 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 111 if (out_page == NULL) { 112 ret = -ENOMEM; 113 goto out; 114 } 115 cpage_out = kmap(out_page); 116 pages[0] = out_page; 117 nr_pages = 1; 118 119 workspace->strm.next_in = data_in; 120 workspace->strm.next_out = cpage_out; 121 workspace->strm.avail_out = PAGE_SIZE; 122 workspace->strm.avail_in = min(len, PAGE_SIZE); 123 124 while (workspace->strm.total_in < len) { 125 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH); 126 if (ret != Z_OK) { 127 pr_debug("BTRFS: deflate in loop returned %d\n", 128 ret); 129 zlib_deflateEnd(&workspace->strm); 130 ret = -EIO; 131 goto out; 132 } 133 134 /* we're making it bigger, give up */ 135 if (workspace->strm.total_in > 8192 && 136 workspace->strm.total_in < 137 workspace->strm.total_out) { 138 ret = -E2BIG; 139 goto out; 140 } 141 /* we need another page for writing out. Test this 142 * before the total_in so we will pull in a new page for 143 * the stream end if required 144 */ 145 if (workspace->strm.avail_out == 0) { 146 kunmap(out_page); 147 if (nr_pages == nr_dest_pages) { 148 out_page = NULL; 149 ret = -E2BIG; 150 goto out; 151 } 152 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); 153 if (out_page == NULL) { 154 ret = -ENOMEM; 155 goto out; 156 } 157 cpage_out = kmap(out_page); 158 pages[nr_pages] = out_page; 159 nr_pages++; 160 workspace->strm.avail_out = PAGE_SIZE; 161 workspace->strm.next_out = cpage_out; 162 } 163 /* we're all done */ 164 if (workspace->strm.total_in >= len) 165 break; 166 167 /* we've read in a full page, get a new one */ 168 if (workspace->strm.avail_in == 0) { 169 if (workspace->strm.total_out > max_out) 170 break; 171 172 bytes_left = len - workspace->strm.total_in; 173 kunmap(in_page); 174 put_page(in_page); 175 176 start += PAGE_SIZE; 177 in_page = find_get_page(mapping, 178 start >> PAGE_SHIFT); 179 data_in = kmap(in_page); 180 workspace->strm.avail_in = min(bytes_left, 181 PAGE_SIZE); 182 workspace->strm.next_in = data_in; 183 } 184 } 185 workspace->strm.avail_in = 0; 186 ret = zlib_deflate(&workspace->strm, Z_FINISH); 187 zlib_deflateEnd(&workspace->strm); 188 189 if (ret != Z_STREAM_END) { 190 ret = -EIO; 191 goto out; 192 } 193 194 if (workspace->strm.total_out >= workspace->strm.total_in) { 195 ret = -E2BIG; 196 goto out; 197 } 198 199 ret = 0; 200 *total_out = workspace->strm.total_out; 201 *total_in = workspace->strm.total_in; 202 out: 203 *out_pages = nr_pages; 204 if (out_page) 205 kunmap(out_page); 206 207 if (in_page) { 208 kunmap(in_page); 209 put_page(in_page); 210 } 211 return ret; 212 } 213 214 static int zlib_decompress_bio(struct list_head *ws, struct page **pages_in, 215 u64 disk_start, 216 struct bio *orig_bio, 217 size_t srclen) 218 { 219 struct workspace *workspace = list_entry(ws, struct workspace, list); 220 int ret = 0, ret2; 221 int wbits = MAX_WBITS; 222 char *data_in; 223 size_t total_out = 0; 224 unsigned long page_in_index = 0; 225 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); 226 unsigned long buf_start; 227 228 data_in = kmap(pages_in[page_in_index]); 229 workspace->strm.next_in = data_in; 230 workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE); 231 workspace->strm.total_in = 0; 232 233 workspace->strm.total_out = 0; 234 workspace->strm.next_out = workspace->buf; 235 workspace->strm.avail_out = PAGE_SIZE; 236 237 /* If it's deflate, and it's got no preset dictionary, then 238 we can tell zlib to skip the adler32 check. */ 239 if (srclen > 2 && !(data_in[1] & PRESET_DICT) && 240 ((data_in[0] & 0x0f) == Z_DEFLATED) && 241 !(((data_in[0]<<8) + data_in[1]) % 31)) { 242 243 wbits = -((data_in[0] >> 4) + 8); 244 workspace->strm.next_in += 2; 245 workspace->strm.avail_in -= 2; 246 } 247 248 if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) { 249 pr_warn("BTRFS: inflateInit failed\n"); 250 kunmap(pages_in[page_in_index]); 251 return -EIO; 252 } 253 while (workspace->strm.total_in < srclen) { 254 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH); 255 if (ret != Z_OK && ret != Z_STREAM_END) 256 break; 257 258 buf_start = total_out; 259 total_out = workspace->strm.total_out; 260 261 /* we didn't make progress in this inflate call, we're done */ 262 if (buf_start == total_out) 263 break; 264 265 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, 266 total_out, disk_start, 267 orig_bio); 268 if (ret2 == 0) { 269 ret = 0; 270 goto done; 271 } 272 273 workspace->strm.next_out = workspace->buf; 274 workspace->strm.avail_out = PAGE_SIZE; 275 276 if (workspace->strm.avail_in == 0) { 277 unsigned long tmp; 278 kunmap(pages_in[page_in_index]); 279 page_in_index++; 280 if (page_in_index >= total_pages_in) { 281 data_in = NULL; 282 break; 283 } 284 data_in = kmap(pages_in[page_in_index]); 285 workspace->strm.next_in = data_in; 286 tmp = srclen - workspace->strm.total_in; 287 workspace->strm.avail_in = min(tmp, 288 PAGE_SIZE); 289 } 290 } 291 if (ret != Z_STREAM_END) 292 ret = -EIO; 293 else 294 ret = 0; 295 done: 296 zlib_inflateEnd(&workspace->strm); 297 if (data_in) 298 kunmap(pages_in[page_in_index]); 299 if (!ret) 300 zero_fill_bio(orig_bio); 301 return ret; 302 } 303 304 static int zlib_decompress(struct list_head *ws, unsigned char *data_in, 305 struct page *dest_page, 306 unsigned long start_byte, 307 size_t srclen, size_t destlen) 308 { 309 struct workspace *workspace = list_entry(ws, struct workspace, list); 310 int ret = 0; 311 int wbits = MAX_WBITS; 312 unsigned long bytes_left; 313 unsigned long total_out = 0; 314 unsigned long pg_offset = 0; 315 char *kaddr; 316 317 destlen = min_t(unsigned long, destlen, PAGE_SIZE); 318 bytes_left = destlen; 319 320 workspace->strm.next_in = data_in; 321 workspace->strm.avail_in = srclen; 322 workspace->strm.total_in = 0; 323 324 workspace->strm.next_out = workspace->buf; 325 workspace->strm.avail_out = PAGE_SIZE; 326 workspace->strm.total_out = 0; 327 /* If it's deflate, and it's got no preset dictionary, then 328 we can tell zlib to skip the adler32 check. */ 329 if (srclen > 2 && !(data_in[1] & PRESET_DICT) && 330 ((data_in[0] & 0x0f) == Z_DEFLATED) && 331 !(((data_in[0]<<8) + data_in[1]) % 31)) { 332 333 wbits = -((data_in[0] >> 4) + 8); 334 workspace->strm.next_in += 2; 335 workspace->strm.avail_in -= 2; 336 } 337 338 if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) { 339 pr_warn("BTRFS: inflateInit failed\n"); 340 return -EIO; 341 } 342 343 while (bytes_left > 0) { 344 unsigned long buf_start; 345 unsigned long buf_offset; 346 unsigned long bytes; 347 348 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH); 349 if (ret != Z_OK && ret != Z_STREAM_END) 350 break; 351 352 buf_start = total_out; 353 total_out = workspace->strm.total_out; 354 355 if (total_out == buf_start) { 356 ret = -EIO; 357 break; 358 } 359 360 if (total_out <= start_byte) 361 goto next; 362 363 if (total_out > start_byte && buf_start < start_byte) 364 buf_offset = start_byte - buf_start; 365 else 366 buf_offset = 0; 367 368 bytes = min(PAGE_SIZE - pg_offset, 369 PAGE_SIZE - buf_offset); 370 bytes = min(bytes, bytes_left); 371 372 kaddr = kmap_atomic(dest_page); 373 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes); 374 kunmap_atomic(kaddr); 375 376 pg_offset += bytes; 377 bytes_left -= bytes; 378 next: 379 workspace->strm.next_out = workspace->buf; 380 workspace->strm.avail_out = PAGE_SIZE; 381 } 382 383 if (ret != Z_STREAM_END && bytes_left != 0) 384 ret = -EIO; 385 else 386 ret = 0; 387 388 zlib_inflateEnd(&workspace->strm); 389 390 /* 391 * this should only happen if zlib returned fewer bytes than we 392 * expected. btrfs_get_block is responsible for zeroing from the 393 * end of the inline extent (destlen) to the end of the page 394 */ 395 if (pg_offset < destlen) { 396 kaddr = kmap_atomic(dest_page); 397 memset(kaddr + pg_offset, 0, destlen - pg_offset); 398 kunmap_atomic(kaddr); 399 } 400 return ret; 401 } 402 403 const struct btrfs_compress_op btrfs_zlib_compress = { 404 .alloc_workspace = zlib_alloc_workspace, 405 .free_workspace = zlib_free_workspace, 406 .compress_pages = zlib_compress_pages, 407 .decompress_bio = zlib_decompress_bio, 408 .decompress = zlib_decompress, 409 }; 410