Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Squashfs - a compressed read only filesystem for Linux |
| 3 | * |
| 4 | * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
Phillip Lougher | d7f2ff6 | 2011-05-26 10:39:56 +0100 | [diff] [blame] | 5 | * Phillip Lougher <phillip@squashfs.org.uk> |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 6 | * |
| 7 | * This program is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU General Public License |
| 9 | * as published by the Free Software Foundation; either version 2, |
| 10 | * or (at your option) any later version. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License |
| 18 | * along with this program; if not, write to the Free Software |
| 19 | * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 20 | * |
| 21 | * file.c |
| 22 | */ |
| 23 | |
| 24 | /* |
| 25 | * This file contains code for handling regular files. A regular file |
| 26 | * consists of a sequence of contiguous compressed blocks, and/or a |
| 27 | * compressed fragment block (tail-end packed block). The compressed size |
| 28 | * of each datablock is stored in a block list contained within the |
| 29 | * file inode (itself stored in one or more compressed metadata blocks). |
| 30 | * |
| 31 | * To speed up access to datablocks when reading 'large' files (256 Mbytes or |
| 32 | * larger), the code implements an index cache that caches the mapping from |
| 33 | * block index to datablock location on disk. |
| 34 | * |
| 35 | * The index cache allows Squashfs to handle large files (up to 1.75 TiB) while |
| 36 | * retaining a simple and space-efficient block list on disk. The cache |
| 37 | * is split into slots, caching up to eight 224 GiB files (128 KiB blocks). |
| 38 | * Larger files use multiple slots, with 1.75 TiB files using all 8 slots. |
| 39 | * The index cache is designed to be memory efficient, and by default uses |
| 40 | * 16 KiB. |
| 41 | */ |
| 42 | |
| 43 | #include <linux/fs.h> |
| 44 | #include <linux/vfs.h> |
| 45 | #include <linux/kernel.h> |
| 46 | #include <linux/slab.h> |
| 47 | #include <linux/string.h> |
| 48 | #include <linux/pagemap.h> |
| 49 | #include <linux/mutex.h> |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 50 | #include <linux/mm_inline.h> |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 51 | |
| 52 | #include "squashfs_fs.h" |
| 53 | #include "squashfs_fs_sb.h" |
| 54 | #include "squashfs_fs_i.h" |
| 55 | #include "squashfs.h" |
| 56 | |
| 57 | /* |
| 58 | * Locate cache slot in range [offset, index] for specified inode. If |
| 59 | * there's more than one return the slot closest to index. |
| 60 | */ |
| 61 | static struct meta_index *locate_meta_index(struct inode *inode, int offset, |
| 62 | int index) |
| 63 | { |
| 64 | struct meta_index *meta = NULL; |
| 65 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 66 | int i; |
| 67 | |
| 68 | mutex_lock(&msblk->meta_index_mutex); |
| 69 | |
| 70 | TRACE("locate_meta_index: index %d, offset %d\n", index, offset); |
| 71 | |
| 72 | if (msblk->meta_index == NULL) |
| 73 | goto not_allocated; |
| 74 | |
| 75 | for (i = 0; i < SQUASHFS_META_SLOTS; i++) { |
| 76 | if (msblk->meta_index[i].inode_number == inode->i_ino && |
| 77 | msblk->meta_index[i].offset >= offset && |
| 78 | msblk->meta_index[i].offset <= index && |
| 79 | msblk->meta_index[i].locked == 0) { |
| 80 | TRACE("locate_meta_index: entry %d, offset %d\n", i, |
| 81 | msblk->meta_index[i].offset); |
| 82 | meta = &msblk->meta_index[i]; |
| 83 | offset = meta->offset; |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | if (meta) |
| 88 | meta->locked = 1; |
| 89 | |
| 90 | not_allocated: |
| 91 | mutex_unlock(&msblk->meta_index_mutex); |
| 92 | |
| 93 | return meta; |
| 94 | } |
| 95 | |
| 96 | |
| 97 | /* |
| 98 | * Find and initialise an empty cache slot for index offset. |
| 99 | */ |
| 100 | static struct meta_index *empty_meta_index(struct inode *inode, int offset, |
| 101 | int skip) |
| 102 | { |
| 103 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 104 | struct meta_index *meta = NULL; |
| 105 | int i; |
| 106 | |
| 107 | mutex_lock(&msblk->meta_index_mutex); |
| 108 | |
| 109 | TRACE("empty_meta_index: offset %d, skip %d\n", offset, skip); |
| 110 | |
| 111 | if (msblk->meta_index == NULL) { |
| 112 | /* |
| 113 | * First time cache index has been used, allocate and |
| 114 | * initialise. The cache index could be allocated at |
| 115 | * mount time but doing it here means it is allocated only |
| 116 | * if a 'large' file is read. |
| 117 | */ |
| 118 | msblk->meta_index = kcalloc(SQUASHFS_META_SLOTS, |
| 119 | sizeof(*(msblk->meta_index)), GFP_KERNEL); |
| 120 | if (msblk->meta_index == NULL) { |
| 121 | ERROR("Failed to allocate meta_index\n"); |
| 122 | goto failed; |
| 123 | } |
| 124 | for (i = 0; i < SQUASHFS_META_SLOTS; i++) { |
| 125 | msblk->meta_index[i].inode_number = 0; |
| 126 | msblk->meta_index[i].locked = 0; |
| 127 | } |
| 128 | msblk->next_meta_index = 0; |
| 129 | } |
| 130 | |
| 131 | for (i = SQUASHFS_META_SLOTS; i && |
| 132 | msblk->meta_index[msblk->next_meta_index].locked; i--) |
| 133 | msblk->next_meta_index = (msblk->next_meta_index + 1) % |
| 134 | SQUASHFS_META_SLOTS; |
| 135 | |
| 136 | if (i == 0) { |
| 137 | TRACE("empty_meta_index: failed!\n"); |
| 138 | goto failed; |
| 139 | } |
| 140 | |
| 141 | TRACE("empty_meta_index: returned meta entry %d, %p\n", |
| 142 | msblk->next_meta_index, |
| 143 | &msblk->meta_index[msblk->next_meta_index]); |
| 144 | |
| 145 | meta = &msblk->meta_index[msblk->next_meta_index]; |
| 146 | msblk->next_meta_index = (msblk->next_meta_index + 1) % |
| 147 | SQUASHFS_META_SLOTS; |
| 148 | |
| 149 | meta->inode_number = inode->i_ino; |
| 150 | meta->offset = offset; |
| 151 | meta->skip = skip; |
| 152 | meta->entries = 0; |
| 153 | meta->locked = 1; |
| 154 | |
| 155 | failed: |
| 156 | mutex_unlock(&msblk->meta_index_mutex); |
| 157 | return meta; |
| 158 | } |
| 159 | |
| 160 | |
| 161 | static void release_meta_index(struct inode *inode, struct meta_index *meta) |
| 162 | { |
| 163 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 164 | mutex_lock(&msblk->meta_index_mutex); |
| 165 | meta->locked = 0; |
| 166 | mutex_unlock(&msblk->meta_index_mutex); |
| 167 | } |
| 168 | |
| 169 | |
| 170 | /* |
| 171 | * Read the next n blocks from the block list, starting from |
| 172 | * metadata block <start_block, offset>. |
| 173 | */ |
| 174 | static long long read_indexes(struct super_block *sb, int n, |
| 175 | u64 *start_block, int *offset) |
| 176 | { |
| 177 | int err, i; |
| 178 | long long block = 0; |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 179 | __le32 *blist = kmalloc(PAGE_SIZE, GFP_KERNEL); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 180 | |
| 181 | if (blist == NULL) { |
| 182 | ERROR("read_indexes: Failed to allocate block_list\n"); |
| 183 | return -ENOMEM; |
| 184 | } |
| 185 | |
| 186 | while (n) { |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 187 | int blocks = min_t(int, n, PAGE_SIZE >> 2); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 188 | |
| 189 | err = squashfs_read_metadata(sb, blist, start_block, |
| 190 | offset, blocks << 2); |
| 191 | if (err < 0) { |
| 192 | ERROR("read_indexes: reading block [%llx:%x]\n", |
| 193 | *start_block, *offset); |
| 194 | goto failure; |
| 195 | } |
| 196 | |
| 197 | for (i = 0; i < blocks; i++) { |
Linus Torvalds | 1aecbe4 | 2018-07-29 12:44:46 -0700 | [diff] [blame] | 198 | int size = squashfs_block_size(blist[i]); |
| 199 | if (size < 0) { |
| 200 | err = size; |
| 201 | goto failure; |
| 202 | } |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 203 | block += SQUASHFS_COMPRESSED_SIZE_BLOCK(size); |
| 204 | } |
| 205 | n -= blocks; |
| 206 | } |
| 207 | |
| 208 | kfree(blist); |
| 209 | return block; |
| 210 | |
| 211 | failure: |
| 212 | kfree(blist); |
| 213 | return err; |
| 214 | } |
| 215 | |
| 216 | |
| 217 | /* |
| 218 | * Each cache index slot has SQUASHFS_META_ENTRIES, each of which |
| 219 | * can cache one index -> datablock/blocklist-block mapping. We wish |
| 220 | * to distribute these over the length of the file, entry[0] maps index x, |
| 221 | * entry[1] maps index x + skip, entry[2] maps index x + 2 * skip, and so on. |
| 222 | * The larger the file, the greater the skip factor. The skip factor is |
| 223 | * limited to the size of the metadata cache (SQUASHFS_CACHED_BLKS) to ensure |
| 224 | * the number of metadata blocks that need to be read fits into the cache. |
| 225 | * If the skip factor is limited in this way then the file will use multiple |
| 226 | * slots. |
| 227 | */ |
| 228 | static inline int calculate_skip(int blocks) |
| 229 | { |
| 230 | int skip = blocks / ((SQUASHFS_META_ENTRIES + 1) |
| 231 | * SQUASHFS_META_INDEXES); |
| 232 | return min(SQUASHFS_CACHED_BLKS - 1, skip + 1); |
| 233 | } |
| 234 | |
| 235 | |
| 236 | /* |
| 237 | * Search and grow the index cache for the specified inode, returning the |
| 238 | * on-disk locations of the datablock and block list metadata block |
| 239 | * <index_block, index_offset> for index (scaled to nearest cache index). |
| 240 | */ |
| 241 | static int fill_meta_index(struct inode *inode, int index, |
| 242 | u64 *index_block, int *index_offset, u64 *data_block) |
| 243 | { |
| 244 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 245 | int skip = calculate_skip(i_size_read(inode) >> msblk->block_log); |
| 246 | int offset = 0; |
| 247 | struct meta_index *meta; |
| 248 | struct meta_entry *meta_entry; |
| 249 | u64 cur_index_block = squashfs_i(inode)->block_list_start; |
| 250 | int cur_offset = squashfs_i(inode)->offset; |
| 251 | u64 cur_data_block = squashfs_i(inode)->start; |
| 252 | int err, i; |
| 253 | |
| 254 | /* |
| 255 | * Scale index to cache index (cache slot entry) |
| 256 | */ |
| 257 | index /= SQUASHFS_META_INDEXES * skip; |
| 258 | |
| 259 | while (offset < index) { |
| 260 | meta = locate_meta_index(inode, offset + 1, index); |
| 261 | |
| 262 | if (meta == NULL) { |
| 263 | meta = empty_meta_index(inode, offset + 1, skip); |
| 264 | if (meta == NULL) |
| 265 | goto all_done; |
| 266 | } else { |
| 267 | offset = index < meta->offset + meta->entries ? index : |
| 268 | meta->offset + meta->entries - 1; |
| 269 | meta_entry = &meta->meta_entry[offset - meta->offset]; |
| 270 | cur_index_block = meta_entry->index_block + |
| 271 | msblk->inode_table; |
| 272 | cur_offset = meta_entry->offset; |
| 273 | cur_data_block = meta_entry->data_block; |
| 274 | TRACE("get_meta_index: offset %d, meta->offset %d, " |
| 275 | "meta->entries %d\n", offset, meta->offset, |
| 276 | meta->entries); |
| 277 | TRACE("get_meta_index: index_block 0x%llx, offset 0x%x" |
| 278 | " data_block 0x%llx\n", cur_index_block, |
| 279 | cur_offset, cur_data_block); |
| 280 | } |
| 281 | |
| 282 | /* |
| 283 | * If necessary grow cache slot by reading block list. Cache |
| 284 | * slot is extended up to index or to the end of the slot, in |
| 285 | * which case further slots will be used. |
| 286 | */ |
| 287 | for (i = meta->offset + meta->entries; i <= index && |
| 288 | i < meta->offset + SQUASHFS_META_ENTRIES; i++) { |
| 289 | int blocks = skip * SQUASHFS_META_INDEXES; |
| 290 | long long res = read_indexes(inode->i_sb, blocks, |
| 291 | &cur_index_block, &cur_offset); |
| 292 | |
| 293 | if (res < 0) { |
| 294 | if (meta->entries == 0) |
| 295 | /* |
| 296 | * Don't leave an empty slot on read |
| 297 | * error allocated to this inode... |
| 298 | */ |
| 299 | meta->inode_number = 0; |
| 300 | err = res; |
| 301 | goto failed; |
| 302 | } |
| 303 | |
| 304 | cur_data_block += res; |
| 305 | meta_entry = &meta->meta_entry[i - meta->offset]; |
| 306 | meta_entry->index_block = cur_index_block - |
| 307 | msblk->inode_table; |
| 308 | meta_entry->offset = cur_offset; |
| 309 | meta_entry->data_block = cur_data_block; |
| 310 | meta->entries++; |
| 311 | offset++; |
| 312 | } |
| 313 | |
| 314 | TRACE("get_meta_index: meta->offset %d, meta->entries %d\n", |
| 315 | meta->offset, meta->entries); |
| 316 | |
| 317 | release_meta_index(inode, meta); |
| 318 | } |
| 319 | |
| 320 | all_done: |
| 321 | *index_block = cur_index_block; |
| 322 | *index_offset = cur_offset; |
| 323 | *data_block = cur_data_block; |
| 324 | |
| 325 | /* |
| 326 | * Scale cache index (cache slot entry) to index |
| 327 | */ |
| 328 | return offset * SQUASHFS_META_INDEXES * skip; |
| 329 | |
| 330 | failed: |
| 331 | release_meta_index(inode, meta); |
| 332 | return err; |
| 333 | } |
| 334 | |
| 335 | |
| 336 | /* |
| 337 | * Get the on-disk location and compressed size of the datablock |
| 338 | * specified by index. Fill_meta_index() does most of the work. |
| 339 | */ |
| 340 | static int read_blocklist(struct inode *inode, int index, u64 *block) |
| 341 | { |
| 342 | u64 start; |
| 343 | long long blks; |
| 344 | int offset; |
| 345 | __le32 size; |
| 346 | int res = fill_meta_index(inode, index, &start, &offset, block); |
| 347 | |
| 348 | TRACE("read_blocklist: res %d, index %d, start 0x%llx, offset" |
| 349 | " 0x%x, block 0x%llx\n", res, index, start, offset, |
| 350 | *block); |
| 351 | |
| 352 | if (res < 0) |
| 353 | return res; |
| 354 | |
| 355 | /* |
| 356 | * res contains the index of the mapping returned by fill_meta_index(), |
| 357 | * this will likely be less than the desired index (because the |
| 358 | * meta_index cache works at a higher granularity). Read any |
| 359 | * extra block indexes needed. |
| 360 | */ |
| 361 | if (res < index) { |
| 362 | blks = read_indexes(inode->i_sb, index - res, &start, &offset); |
| 363 | if (blks < 0) |
| 364 | return (int) blks; |
| 365 | *block += blks; |
| 366 | } |
| 367 | |
| 368 | /* |
| 369 | * Read length of block specified by index. |
| 370 | */ |
| 371 | res = squashfs_read_metadata(inode->i_sb, &size, &start, &offset, |
| 372 | sizeof(size)); |
| 373 | if (res < 0) |
| 374 | return res; |
Linus Torvalds | 1aecbe4 | 2018-07-29 12:44:46 -0700 | [diff] [blame] | 375 | return squashfs_block_size(size); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 376 | } |
| 377 | |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 378 | /* Copy data into page cache */ |
| 379 | void squashfs_copy_cache(struct page *page, struct squashfs_cache_entry *buffer, |
| 380 | int bytes, int offset) |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 381 | { |
| 382 | struct inode *inode = page->mapping->host; |
| 383 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 384 | void *pageaddr; |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 385 | int i, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 386 | int start_index = page->index & ~mask, end_index = start_index | mask; |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 387 | |
| 388 | /* |
| 389 | * Loop copying datablock into pages. As the datablock likely covers |
Kirill A. Shutemov | ea1754a | 2016-04-01 15:29:48 +0300 | [diff] [blame] | 390 | * many PAGE_SIZE pages (default block size is 128 KiB) explicitly |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 391 | * grab the pages from the page cache, except for the page that we've |
| 392 | * been called to fill. |
| 393 | */ |
| 394 | for (i = start_index; i <= end_index && bytes > 0; i++, |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 395 | bytes -= PAGE_SIZE, offset += PAGE_SIZE) { |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 396 | struct page *push_page; |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 397 | int avail = buffer ? min_t(int, bytes, PAGE_SIZE) : 0; |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 398 | |
| 399 | TRACE("bytes %d, i %d, available_bytes %d\n", bytes, i, avail); |
| 400 | |
| 401 | push_page = (i == page->index) ? page : |
| 402 | grab_cache_page_nowait(page->mapping, i); |
| 403 | |
| 404 | if (!push_page) |
| 405 | continue; |
| 406 | |
| 407 | if (PageUptodate(push_page)) |
| 408 | goto skip_page; |
| 409 | |
Cong Wang | 53b55e5 | 2011-11-25 23:14:36 +0800 | [diff] [blame] | 410 | pageaddr = kmap_atomic(push_page); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 411 | squashfs_copy_data(pageaddr, buffer, offset, avail); |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 412 | memset(pageaddr + avail, 0, PAGE_SIZE - avail); |
Cong Wang | 53b55e5 | 2011-11-25 23:14:36 +0800 | [diff] [blame] | 413 | kunmap_atomic(pageaddr); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 414 | flush_dcache_page(push_page); |
| 415 | SetPageUptodate(push_page); |
| 416 | skip_page: |
| 417 | unlock_page(push_page); |
| 418 | if (i != page->index) |
Kirill A. Shutemov | 09cbfea | 2016-04-01 15:29:47 +0300 | [diff] [blame] | 419 | put_page(push_page); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 420 | } |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 421 | } |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 422 | |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 423 | /* Read datablock stored packed inside a fragment (tail-end packed block) */ |
| 424 | static int squashfs_readpage_fragment(struct page *page) |
| 425 | { |
| 426 | struct inode *inode = page->mapping->host; |
| 427 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 428 | struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb, |
| 429 | squashfs_i(inode)->fragment_block, |
| 430 | squashfs_i(inode)->fragment_size); |
| 431 | int res = buffer->error; |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 432 | |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 433 | if (res) |
| 434 | ERROR("Unable to read page, block %llx, size %x\n", |
| 435 | squashfs_i(inode)->fragment_block, |
| 436 | squashfs_i(inode)->fragment_size); |
| 437 | else |
| 438 | squashfs_copy_cache(page, buffer, i_size_read(inode) & |
| 439 | (msblk->block_size - 1), |
| 440 | squashfs_i(inode)->fragment_offset); |
| 441 | |
| 442 | squashfs_cache_put(buffer); |
| 443 | return res; |
| 444 | } |
| 445 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 446 | static int squashfs_readpages_fragment(struct page *page, |
| 447 | struct list_head *readahead_pages, struct address_space *mapping) |
| 448 | { |
| 449 | if (!page) { |
| 450 | page = lru_to_page(readahead_pages); |
| 451 | list_del(&page->lru); |
| 452 | if (add_to_page_cache_lru(page, mapping, page->index, |
| 453 | mapping_gfp_constraint(mapping, GFP_KERNEL))) { |
| 454 | put_page(page); |
| 455 | return 0; |
| 456 | } |
| 457 | } |
| 458 | return squashfs_readpage_fragment(page); |
| 459 | } |
| 460 | |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 461 | static int squashfs_readpage_sparse(struct page *page, int index, int file_end) |
| 462 | { |
| 463 | struct inode *inode = page->mapping->host; |
| 464 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
| 465 | int bytes = index == file_end ? |
| 466 | (i_size_read(inode) & (msblk->block_size - 1)) : |
| 467 | msblk->block_size; |
| 468 | |
| 469 | squashfs_copy_cache(page, NULL, bytes, 0); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 470 | return 0; |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 471 | } |
| 472 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 473 | static int squashfs_readpages_sparse(struct page *page, |
| 474 | struct list_head *readahead_pages, int index, int file_end, |
| 475 | struct address_space *mapping) |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 476 | { |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 477 | if (!page) { |
| 478 | page = lru_to_page(readahead_pages); |
| 479 | list_del(&page->lru); |
| 480 | if (add_to_page_cache_lru(page, mapping, page->index, |
| 481 | mapping_gfp_constraint(mapping, GFP_KERNEL))) { |
| 482 | put_page(page); |
| 483 | return 0; |
| 484 | } |
| 485 | } |
| 486 | return squashfs_readpage_sparse(page, index, file_end); |
| 487 | } |
| 488 | |
| 489 | static int __squashfs_readpages(struct file *file, struct page *page, |
| 490 | struct list_head *readahead_pages, unsigned int nr_pages, |
| 491 | struct address_space *mapping) |
| 492 | { |
| 493 | struct inode *inode = mapping->host; |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 494 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 495 | int file_end = i_size_read(inode) >> msblk->block_log; |
| 496 | int res; |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 497 | |
| 498 | do { |
| 499 | struct page *cur_page = page ? page |
| 500 | : lru_to_page(readahead_pages); |
| 501 | int page_index = cur_page->index; |
| 502 | int index = page_index >> (msblk->block_log - PAGE_SHIFT); |
| 503 | |
| 504 | if (page_index >= ((i_size_read(inode) + PAGE_SIZE - 1) >> |
| 505 | PAGE_SHIFT)) |
| 506 | return 1; |
| 507 | |
| 508 | if (index < file_end || squashfs_i(inode)->fragment_block == |
| 509 | SQUASHFS_INVALID_BLK) { |
| 510 | u64 block = 0; |
| 511 | int bsize = read_blocklist(inode, index, &block); |
| 512 | |
| 513 | if (bsize < 0) |
| 514 | return -1; |
| 515 | |
| 516 | if (bsize == 0) { |
| 517 | res = squashfs_readpages_sparse(page, |
| 518 | readahead_pages, index, file_end, |
| 519 | mapping); |
| 520 | } else { |
| 521 | res = squashfs_readpages_block(page, |
| 522 | readahead_pages, &nr_pages, mapping, |
| 523 | page_index, block, bsize); |
| 524 | } |
| 525 | } else { |
| 526 | res = squashfs_readpages_fragment(page, |
| 527 | readahead_pages, mapping); |
| 528 | } |
| 529 | if (res) |
| 530 | return 0; |
| 531 | page = NULL; |
| 532 | } while (readahead_pages && !list_empty(readahead_pages)); |
| 533 | |
| 534 | return 0; |
| 535 | } |
| 536 | |
| 537 | static int squashfs_readpage(struct file *file, struct page *page) |
| 538 | { |
| 539 | int ret; |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 540 | |
| 541 | TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n", |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 542 | page->index, squashfs_i(page->mapping->host)->start); |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 543 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 544 | get_page(page); |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 545 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 546 | ret = __squashfs_readpages(file, page, NULL, 1, page->mapping); |
| 547 | if (ret) { |
| 548 | flush_dcache_page(page); |
| 549 | if (ret < 0) |
| 550 | SetPageError(page); |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 551 | else |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 552 | SetPageUptodate(page); |
| 553 | zero_user_segment(page, 0, PAGE_SIZE); |
| 554 | unlock_page(page); |
| 555 | put_page(page); |
| 556 | } |
Phillip Lougher | 5f55dbc | 2013-10-31 19:24:27 +0000 | [diff] [blame] | 557 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 558 | return 0; |
| 559 | } |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 560 | |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 561 | static int squashfs_readpages(struct file *file, struct address_space *mapping, |
| 562 | struct list_head *pages, unsigned int nr_pages) |
| 563 | { |
| 564 | TRACE("Entered squashfs_readpages, %u pages, first page index %lx\n", |
| 565 | nr_pages, lru_to_page(pages)->index); |
| 566 | __squashfs_readpages(file, NULL, pages, nr_pages, mapping); |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 567 | return 0; |
| 568 | } |
| 569 | |
| 570 | |
| 571 | const struct address_space_operations squashfs_aops = { |
Adrien Schildknecht | d840c1d | 2016-10-14 21:03:54 -0700 | [diff] [blame] | 572 | .readpage = squashfs_readpage, |
| 573 | .readpages = squashfs_readpages, |
Phillip Lougher | 1701aec | 2009-01-05 08:46:24 +0000 | [diff] [blame] | 574 | }; |