diff options
Diffstat (limited to 'fs/ntfs/compress.c')
-rw-r--r-- | fs/ntfs/compress.c | 957 |
1 files changed, 957 insertions, 0 deletions
diff --git a/fs/ntfs/compress.c b/fs/ntfs/compress.c new file mode 100644 index 000000000000..ee5ae706f861 --- /dev/null +++ b/fs/ntfs/compress.c | |||
@@ -0,0 +1,957 @@ | |||
1 | /** | ||
2 | * compress.c - NTFS kernel compressed attributes handling. | ||
3 | * Part of the Linux-NTFS project. | ||
4 | * | ||
5 | * Copyright (c) 2001-2004 Anton Altaparmakov | ||
6 | * Copyright (c) 2002 Richard Russon | ||
7 | * | ||
8 | * This program/include file is free software; you can redistribute it and/or | ||
9 | * modify it under the terms of the GNU General Public License as published | ||
10 | * by the Free Software Foundation; either version 2 of the License, or | ||
11 | * (at your option) any later version. | ||
12 | * | ||
13 | * This program/include file is distributed in the hope that it will be | ||
14 | * useful, but WITHOUT ANY WARRANTY; without even the implied warranty | ||
15 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
16 | * GNU General Public License for more details. | ||
17 | * | ||
18 | * You should have received a copy of the GNU General Public License | ||
19 | * along with this program (in the main directory of the Linux-NTFS | ||
20 | * distribution in the file COPYING); if not, write to the Free Software | ||
21 | * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
22 | */ | ||
23 | |||
24 | #include <linux/fs.h> | ||
25 | #include <linux/buffer_head.h> | ||
26 | #include <linux/blkdev.h> | ||
27 | #include <linux/vmalloc.h> | ||
28 | |||
29 | #include "attrib.h" | ||
30 | #include "inode.h" | ||
31 | #include "debug.h" | ||
32 | #include "ntfs.h" | ||
33 | |||
34 | /** | ||
35 | * ntfs_compression_constants - enum of constants used in the compression code | ||
36 | */ | ||
37 | typedef enum { | ||
38 | /* Token types and access mask. */ | ||
39 | NTFS_SYMBOL_TOKEN = 0, | ||
40 | NTFS_PHRASE_TOKEN = 1, | ||
41 | NTFS_TOKEN_MASK = 1, | ||
42 | |||
43 | /* Compression sub-block constants. */ | ||
44 | NTFS_SB_SIZE_MASK = 0x0fff, | ||
45 | NTFS_SB_SIZE = 0x1000, | ||
46 | NTFS_SB_IS_COMPRESSED = 0x8000, | ||
47 | |||
48 | /* | ||
49 | * The maximum compression block size is by definition 16 * the cluster | ||
50 | * size, with the maximum supported cluster size being 4kiB. Thus the | ||
51 | * maximum compression buffer size is 64kiB, so we use this when | ||
52 | * initializing the compression buffer. | ||
53 | */ | ||
54 | NTFS_MAX_CB_SIZE = 64 * 1024, | ||
55 | } ntfs_compression_constants; | ||
56 | |||
57 | /** | ||
58 | * ntfs_compression_buffer - one buffer for the decompression engine | ||
59 | */ | ||
60 | static u8 *ntfs_compression_buffer = NULL; | ||
61 | |||
62 | /** | ||
63 | * ntfs_cb_lock - spinlock which protects ntfs_compression_buffer | ||
64 | */ | ||
65 | static DEFINE_SPINLOCK(ntfs_cb_lock); | ||
66 | |||
67 | /** | ||
68 | * allocate_compression_buffers - allocate the decompression buffers | ||
69 | * | ||
70 | * Caller has to hold the ntfs_lock semaphore. | ||
71 | * | ||
72 | * Return 0 on success or -ENOMEM if the allocations failed. | ||
73 | */ | ||
74 | int allocate_compression_buffers(void) | ||
75 | { | ||
76 | BUG_ON(ntfs_compression_buffer); | ||
77 | |||
78 | ntfs_compression_buffer = vmalloc(NTFS_MAX_CB_SIZE); | ||
79 | if (!ntfs_compression_buffer) | ||
80 | return -ENOMEM; | ||
81 | return 0; | ||
82 | } | ||
83 | |||
84 | /** | ||
85 | * free_compression_buffers - free the decompression buffers | ||
86 | * | ||
87 | * Caller has to hold the ntfs_lock semaphore. | ||
88 | */ | ||
89 | void free_compression_buffers(void) | ||
90 | { | ||
91 | BUG_ON(!ntfs_compression_buffer); | ||
92 | vfree(ntfs_compression_buffer); | ||
93 | ntfs_compression_buffer = NULL; | ||
94 | } | ||
95 | |||
96 | /** | ||
97 | * zero_partial_compressed_page - zero out of bounds compressed page region | ||
98 | */ | ||
99 | static void zero_partial_compressed_page(ntfs_inode *ni, struct page *page) | ||
100 | { | ||
101 | u8 *kp = page_address(page); | ||
102 | unsigned int kp_ofs; | ||
103 | |||
104 | ntfs_debug("Zeroing page region outside initialized size."); | ||
105 | if (((s64)page->index << PAGE_CACHE_SHIFT) >= ni->initialized_size) { | ||
106 | /* | ||
107 | * FIXME: Using clear_page() will become wrong when we get | ||
108 | * PAGE_CACHE_SIZE != PAGE_SIZE but for now there is no problem. | ||
109 | */ | ||
110 | clear_page(kp); | ||
111 | return; | ||
112 | } | ||
113 | kp_ofs = ni->initialized_size & ~PAGE_CACHE_MASK; | ||
114 | memset(kp + kp_ofs, 0, PAGE_CACHE_SIZE - kp_ofs); | ||
115 | return; | ||
116 | } | ||
117 | |||
118 | /** | ||
119 | * handle_bounds_compressed_page - test for&handle out of bounds compressed page | ||
120 | */ | ||
121 | static inline void handle_bounds_compressed_page(ntfs_inode *ni, | ||
122 | struct page *page) | ||
123 | { | ||
124 | if ((page->index >= (ni->initialized_size >> PAGE_CACHE_SHIFT)) && | ||
125 | (ni->initialized_size < VFS_I(ni)->i_size)) | ||
126 | zero_partial_compressed_page(ni, page); | ||
127 | return; | ||
128 | } | ||
129 | |||
130 | /** | ||
131 | * ntfs_decompress - decompress a compression block into an array of pages | ||
132 | * @dest_pages: destination array of pages | ||
133 | * @dest_index: current index into @dest_pages (IN/OUT) | ||
134 | * @dest_ofs: current offset within @dest_pages[@dest_index] (IN/OUT) | ||
135 | * @dest_max_index: maximum index into @dest_pages (IN) | ||
136 | * @dest_max_ofs: maximum offset within @dest_pages[@dest_max_index] (IN) | ||
137 | * @xpage: the target page (-1 if none) (IN) | ||
138 | * @xpage_done: set to 1 if xpage was completed successfully (IN/OUT) | ||
139 | * @cb_start: compression block to decompress (IN) | ||
140 | * @cb_size: size of compression block @cb_start in bytes (IN) | ||
141 | * | ||
142 | * The caller must have disabled preemption. ntfs_decompress() reenables it when | ||
143 | * the critical section is finished. | ||
144 | * | ||
145 | * This decompresses the compression block @cb_start into the array of | ||
146 | * destination pages @dest_pages starting at index @dest_index into @dest_pages | ||
147 | * and at offset @dest_pos into the page @dest_pages[@dest_index]. | ||
148 | * | ||
149 | * When the page @dest_pages[@xpage] is completed, @xpage_done is set to 1. | ||
150 | * If xpage is -1 or @xpage has not been completed, @xpage_done is not modified. | ||
151 | * | ||
152 | * @cb_start is a pointer to the compression block which needs decompressing | ||
153 | * and @cb_size is the size of @cb_start in bytes (8-64kiB). | ||
154 | * | ||
155 | * Return 0 if success or -EOVERFLOW on error in the compressed stream. | ||
156 | * @xpage_done indicates whether the target page (@dest_pages[@xpage]) was | ||
157 | * completed during the decompression of the compression block (@cb_start). | ||
158 | * | ||
159 | * Warning: This function *REQUIRES* PAGE_CACHE_SIZE >= 4096 or it will blow up | ||
160 | * unpredicatbly! You have been warned! | ||
161 | * | ||
162 | * Note to hackers: This function may not sleep until it has finished accessing | ||
163 | * the compression block @cb_start as it is a per-CPU buffer. | ||
164 | */ | ||
165 | static int ntfs_decompress(struct page *dest_pages[], int *dest_index, | ||
166 | int *dest_ofs, const int dest_max_index, const int dest_max_ofs, | ||
167 | const int xpage, char *xpage_done, u8 *const cb_start, | ||
168 | const u32 cb_size) | ||
169 | { | ||
170 | /* | ||
171 | * Pointers into the compressed data, i.e. the compression block (cb), | ||
172 | * and the therein contained sub-blocks (sb). | ||
173 | */ | ||
174 | u8 *cb_end = cb_start + cb_size; /* End of cb. */ | ||
175 | u8 *cb = cb_start; /* Current position in cb. */ | ||
176 | u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */ | ||
177 | u8 *cb_sb_end; /* End of current sb / beginning of next sb. */ | ||
178 | |||
179 | /* Variables for uncompressed data / destination. */ | ||
180 | struct page *dp; /* Current destination page being worked on. */ | ||
181 | u8 *dp_addr; /* Current pointer into dp. */ | ||
182 | u8 *dp_sb_start; /* Start of current sub-block in dp. */ | ||
183 | u8 *dp_sb_end; /* End of current sb in dp (dp_sb_start + | ||
184 | NTFS_SB_SIZE). */ | ||
185 | u16 do_sb_start; /* @dest_ofs when starting this sub-block. */ | ||
186 | u16 do_sb_end; /* @dest_ofs of end of this sb (do_sb_start + | ||
187 | NTFS_SB_SIZE). */ | ||
188 | |||
189 | /* Variables for tag and token parsing. */ | ||
190 | u8 tag; /* Current tag. */ | ||
191 | int token; /* Loop counter for the eight tokens in tag. */ | ||
192 | |||
193 | /* Need this because we can't sleep, so need two stages. */ | ||
194 | int completed_pages[dest_max_index - *dest_index + 1]; | ||
195 | int nr_completed_pages = 0; | ||
196 | |||
197 | /* Default error code. */ | ||
198 | int err = -EOVERFLOW; | ||
199 | |||
200 | ntfs_debug("Entering, cb_size = 0x%x.", cb_size); | ||
201 | do_next_sb: | ||
202 | ntfs_debug("Beginning sub-block at offset = 0x%zx in the cb.", | ||
203 | cb - cb_start); | ||
204 | /* | ||
205 | * Have we reached the end of the compression block or the end of the | ||
206 | * decompressed data? The latter can happen for example if the current | ||
207 | * position in the compression block is one byte before its end so the | ||
208 | * first two checks do not detect it. | ||
209 | */ | ||
210 | if (cb == cb_end || !le16_to_cpup((le16*)cb) || | ||
211 | (*dest_index == dest_max_index && | ||
212 | *dest_ofs == dest_max_ofs)) { | ||
213 | int i; | ||
214 | |||
215 | ntfs_debug("Completed. Returning success (0)."); | ||
216 | err = 0; | ||
217 | return_error: | ||
218 | /* We can sleep from now on, so we drop lock. */ | ||
219 | spin_unlock(&ntfs_cb_lock); | ||
220 | /* Second stage: finalize completed pages. */ | ||
221 | if (nr_completed_pages > 0) { | ||
222 | struct page *page = dest_pages[completed_pages[0]]; | ||
223 | ntfs_inode *ni = NTFS_I(page->mapping->host); | ||
224 | |||
225 | for (i = 0; i < nr_completed_pages; i++) { | ||
226 | int di = completed_pages[i]; | ||
227 | |||
228 | dp = dest_pages[di]; | ||
229 | /* | ||
230 | * If we are outside the initialized size, zero | ||
231 | * the out of bounds page range. | ||
232 | */ | ||
233 | handle_bounds_compressed_page(ni, dp); | ||
234 | flush_dcache_page(dp); | ||
235 | kunmap(dp); | ||
236 | SetPageUptodate(dp); | ||
237 | unlock_page(dp); | ||
238 | if (di == xpage) | ||
239 | *xpage_done = 1; | ||
240 | else | ||
241 | page_cache_release(dp); | ||
242 | dest_pages[di] = NULL; | ||
243 | } | ||
244 | } | ||
245 | return err; | ||
246 | } | ||
247 | |||
248 | /* Setup offsets for the current sub-block destination. */ | ||
249 | do_sb_start = *dest_ofs; | ||
250 | do_sb_end = do_sb_start + NTFS_SB_SIZE; | ||
251 | |||
252 | /* Check that we are still within allowed boundaries. */ | ||
253 | if (*dest_index == dest_max_index && do_sb_end > dest_max_ofs) | ||
254 | goto return_overflow; | ||
255 | |||
256 | /* Does the minimum size of a compressed sb overflow valid range? */ | ||
257 | if (cb + 6 > cb_end) | ||
258 | goto return_overflow; | ||
259 | |||
260 | /* Setup the current sub-block source pointers and validate range. */ | ||
261 | cb_sb_start = cb; | ||
262 | cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK) | ||
263 | + 3; | ||
264 | if (cb_sb_end > cb_end) | ||
265 | goto return_overflow; | ||
266 | |||
267 | /* Get the current destination page. */ | ||
268 | dp = dest_pages[*dest_index]; | ||
269 | if (!dp) { | ||
270 | /* No page present. Skip decompression of this sub-block. */ | ||
271 | cb = cb_sb_end; | ||
272 | |||
273 | /* Advance destination position to next sub-block. */ | ||
274 | *dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_CACHE_MASK; | ||
275 | if (!*dest_ofs && (++*dest_index > dest_max_index)) | ||
276 | goto return_overflow; | ||
277 | goto do_next_sb; | ||
278 | } | ||
279 | |||
280 | /* We have a valid destination page. Setup the destination pointers. */ | ||
281 | dp_addr = (u8*)page_address(dp) + do_sb_start; | ||
282 | |||
283 | /* Now, we are ready to process the current sub-block (sb). */ | ||
284 | if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) { | ||
285 | ntfs_debug("Found uncompressed sub-block."); | ||
286 | /* This sb is not compressed, just copy it into destination. */ | ||
287 | |||
288 | /* Advance source position to first data byte. */ | ||
289 | cb += 2; | ||
290 | |||
291 | /* An uncompressed sb must be full size. */ | ||
292 | if (cb_sb_end - cb != NTFS_SB_SIZE) | ||
293 | goto return_overflow; | ||
294 | |||
295 | /* Copy the block and advance the source position. */ | ||
296 | memcpy(dp_addr, cb, NTFS_SB_SIZE); | ||
297 | cb += NTFS_SB_SIZE; | ||
298 | |||
299 | /* Advance destination position to next sub-block. */ | ||
300 | *dest_ofs += NTFS_SB_SIZE; | ||
301 | if (!(*dest_ofs &= ~PAGE_CACHE_MASK)) { | ||
302 | finalize_page: | ||
303 | /* | ||
304 | * First stage: add current page index to array of | ||
305 | * completed pages. | ||
306 | */ | ||
307 | completed_pages[nr_completed_pages++] = *dest_index; | ||
308 | if (++*dest_index > dest_max_index) | ||
309 | goto return_overflow; | ||
310 | } | ||
311 | goto do_next_sb; | ||
312 | } | ||
313 | ntfs_debug("Found compressed sub-block."); | ||
314 | /* This sb is compressed, decompress it into destination. */ | ||
315 | |||
316 | /* Setup destination pointers. */ | ||
317 | dp_sb_start = dp_addr; | ||
318 | dp_sb_end = dp_sb_start + NTFS_SB_SIZE; | ||
319 | |||
320 | /* Forward to the first tag in the sub-block. */ | ||
321 | cb += 2; | ||
322 | do_next_tag: | ||
323 | if (cb == cb_sb_end) { | ||
324 | /* Check if the decompressed sub-block was not full-length. */ | ||
325 | if (dp_addr < dp_sb_end) { | ||
326 | int nr_bytes = do_sb_end - *dest_ofs; | ||
327 | |||
328 | ntfs_debug("Filling incomplete sub-block with " | ||
329 | "zeroes."); | ||
330 | /* Zero remainder and update destination position. */ | ||
331 | memset(dp_addr, 0, nr_bytes); | ||
332 | *dest_ofs += nr_bytes; | ||
333 | } | ||
334 | /* We have finished the current sub-block. */ | ||
335 | if (!(*dest_ofs &= ~PAGE_CACHE_MASK)) | ||
336 | goto finalize_page; | ||
337 | goto do_next_sb; | ||
338 | } | ||
339 | |||
340 | /* Check we are still in range. */ | ||
341 | if (cb > cb_sb_end || dp_addr > dp_sb_end) | ||
342 | goto return_overflow; | ||
343 | |||
344 | /* Get the next tag and advance to first token. */ | ||
345 | tag = *cb++; | ||
346 | |||
347 | /* Parse the eight tokens described by the tag. */ | ||
348 | for (token = 0; token < 8; token++, tag >>= 1) { | ||
349 | u16 lg, pt, length, max_non_overlap; | ||
350 | register u16 i; | ||
351 | u8 *dp_back_addr; | ||
352 | |||
353 | /* Check if we are done / still in range. */ | ||
354 | if (cb >= cb_sb_end || dp_addr > dp_sb_end) | ||
355 | break; | ||
356 | |||
357 | /* Determine token type and parse appropriately.*/ | ||
358 | if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) { | ||
359 | /* | ||
360 | * We have a symbol token, copy the symbol across, and | ||
361 | * advance the source and destination positions. | ||
362 | */ | ||
363 | *dp_addr++ = *cb++; | ||
364 | ++*dest_ofs; | ||
365 | |||
366 | /* Continue with the next token. */ | ||
367 | continue; | ||
368 | } | ||
369 | |||
370 | /* | ||
371 | * We have a phrase token. Make sure it is not the first tag in | ||
372 | * the sb as this is illegal and would confuse the code below. | ||
373 | */ | ||
374 | if (dp_addr == dp_sb_start) | ||
375 | goto return_overflow; | ||
376 | |||
377 | /* | ||
378 | * Determine the number of bytes to go back (p) and the number | ||
379 | * of bytes to copy (l). We use an optimized algorithm in which | ||
380 | * we first calculate log2(current destination position in sb), | ||
381 | * which allows determination of l and p in O(1) rather than | ||
382 | * O(n). We just need an arch-optimized log2() function now. | ||
383 | */ | ||
384 | lg = 0; | ||
385 | for (i = *dest_ofs - do_sb_start - 1; i >= 0x10; i >>= 1) | ||
386 | lg++; | ||
387 | |||
388 | /* Get the phrase token into i. */ | ||
389 | pt = le16_to_cpup((le16*)cb); | ||
390 | |||
391 | /* | ||
392 | * Calculate starting position of the byte sequence in | ||
393 | * the destination using the fact that p = (pt >> (12 - lg)) + 1 | ||
394 | * and make sure we don't go too far back. | ||
395 | */ | ||
396 | dp_back_addr = dp_addr - (pt >> (12 - lg)) - 1; | ||
397 | if (dp_back_addr < dp_sb_start) | ||
398 | goto return_overflow; | ||
399 | |||
400 | /* Now calculate the length of the byte sequence. */ | ||
401 | length = (pt & (0xfff >> lg)) + 3; | ||
402 | |||
403 | /* Advance destination position and verify it is in range. */ | ||
404 | *dest_ofs += length; | ||
405 | if (*dest_ofs > do_sb_end) | ||
406 | goto return_overflow; | ||
407 | |||
408 | /* The number of non-overlapping bytes. */ | ||
409 | max_non_overlap = dp_addr - dp_back_addr; | ||
410 | |||
411 | if (length <= max_non_overlap) { | ||
412 | /* The byte sequence doesn't overlap, just copy it. */ | ||
413 | memcpy(dp_addr, dp_back_addr, length); | ||
414 | |||
415 | /* Advance destination pointer. */ | ||
416 | dp_addr += length; | ||
417 | } else { | ||
418 | /* | ||
419 | * The byte sequence does overlap, copy non-overlapping | ||
420 | * part and then do a slow byte by byte copy for the | ||
421 | * overlapping part. Also, advance the destination | ||
422 | * pointer. | ||
423 | */ | ||
424 | memcpy(dp_addr, dp_back_addr, max_non_overlap); | ||
425 | dp_addr += max_non_overlap; | ||
426 | dp_back_addr += max_non_overlap; | ||
427 | length -= max_non_overlap; | ||
428 | while (length--) | ||
429 | *dp_addr++ = *dp_back_addr++; | ||
430 | } | ||
431 | |||
432 | /* Advance source position and continue with the next token. */ | ||
433 | cb += 2; | ||
434 | } | ||
435 | |||
436 | /* No tokens left in the current tag. Continue with the next tag. */ | ||
437 | goto do_next_tag; | ||
438 | |||
439 | return_overflow: | ||
440 | ntfs_error(NULL, "Failed. Returning -EOVERFLOW."); | ||
441 | goto return_error; | ||
442 | } | ||
443 | |||
444 | /** | ||
445 | * ntfs_read_compressed_block - read a compressed block into the page cache | ||
446 | * @page: locked page in the compression block(s) we need to read | ||
447 | * | ||
448 | * When we are called the page has already been verified to be locked and the | ||
449 | * attribute is known to be non-resident, not encrypted, but compressed. | ||
450 | * | ||
451 | * 1. Determine which compression block(s) @page is in. | ||
452 | * 2. Get hold of all pages corresponding to this/these compression block(s). | ||
453 | * 3. Read the (first) compression block. | ||
454 | * 4. Decompress it into the corresponding pages. | ||
455 | * 5. Throw the compressed data away and proceed to 3. for the next compression | ||
456 | * block or return success if no more compression blocks left. | ||
457 | * | ||
458 | * Warning: We have to be careful what we do about existing pages. They might | ||
459 | * have been written to so that we would lose data if we were to just overwrite | ||
460 | * them with the out-of-date uncompressed data. | ||
461 | * | ||
462 | * FIXME: For PAGE_CACHE_SIZE > cb_size we are not doing the Right Thing(TM) at | ||
463 | * the end of the file I think. We need to detect this case and zero the out | ||
464 | * of bounds remainder of the page in question and mark it as handled. At the | ||
465 | * moment we would just return -EIO on such a page. This bug will only become | ||
466 | * apparent if pages are above 8kiB and the NTFS volume only uses 512 byte | ||
467 | * clusters so is probably not going to be seen by anyone. Still this should | ||
468 | * be fixed. (AIA) | ||
469 | * | ||
470 | * FIXME: Again for PAGE_CACHE_SIZE > cb_size we are screwing up both in | ||
471 | * handling sparse and compressed cbs. (AIA) | ||
472 | * | ||
473 | * FIXME: At the moment we don't do any zeroing out in the case that | ||
474 | * initialized_size is less than data_size. This should be safe because of the | ||
475 | * nature of the compression algorithm used. Just in case we check and output | ||
476 | * an error message in read inode if the two sizes are not equal for a | ||
477 | * compressed file. (AIA) | ||
478 | */ | ||
479 | int ntfs_read_compressed_block(struct page *page) | ||
480 | { | ||
481 | struct address_space *mapping = page->mapping; | ||
482 | ntfs_inode *ni = NTFS_I(mapping->host); | ||
483 | ntfs_volume *vol = ni->vol; | ||
484 | struct super_block *sb = vol->sb; | ||
485 | runlist_element *rl; | ||
486 | unsigned long block_size = sb->s_blocksize; | ||
487 | unsigned char block_size_bits = sb->s_blocksize_bits; | ||
488 | u8 *cb, *cb_pos, *cb_end; | ||
489 | struct buffer_head **bhs; | ||
490 | unsigned long offset, index = page->index; | ||
491 | u32 cb_size = ni->itype.compressed.block_size; | ||
492 | u64 cb_size_mask = cb_size - 1UL; | ||
493 | VCN vcn; | ||
494 | LCN lcn; | ||
495 | /* The first wanted vcn (minimum alignment is PAGE_CACHE_SIZE). */ | ||
496 | VCN start_vcn = (((s64)index << PAGE_CACHE_SHIFT) & ~cb_size_mask) >> | ||
497 | vol->cluster_size_bits; | ||
498 | /* | ||
499 | * The first vcn after the last wanted vcn (minumum alignment is again | ||
500 | * PAGE_CACHE_SIZE. | ||
501 | */ | ||
502 | VCN end_vcn = ((((s64)(index + 1UL) << PAGE_CACHE_SHIFT) + cb_size - 1) | ||
503 | & ~cb_size_mask) >> vol->cluster_size_bits; | ||
504 | /* Number of compression blocks (cbs) in the wanted vcn range. */ | ||
505 | unsigned int nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits | ||
506 | >> ni->itype.compressed.block_size_bits; | ||
507 | /* | ||
508 | * Number of pages required to store the uncompressed data from all | ||
509 | * compression blocks (cbs) overlapping @page. Due to alignment | ||
510 | * guarantees of start_vcn and end_vcn, no need to round up here. | ||
511 | */ | ||
512 | unsigned int nr_pages = (end_vcn - start_vcn) << | ||
513 | vol->cluster_size_bits >> PAGE_CACHE_SHIFT; | ||
514 | unsigned int xpage, max_page, cur_page, cur_ofs, i; | ||
515 | unsigned int cb_clusters, cb_max_ofs; | ||
516 | int block, max_block, cb_max_page, bhs_size, nr_bhs, err = 0; | ||
517 | struct page **pages; | ||
518 | unsigned char xpage_done = 0; | ||
519 | |||
520 | ntfs_debug("Entering, page->index = 0x%lx, cb_size = 0x%x, nr_pages = " | ||
521 | "%i.", index, cb_size, nr_pages); | ||
522 | /* | ||
523 | * Bad things happen if we get here for anything that is not an | ||
524 | * unnamed $DATA attribute. | ||
525 | */ | ||
526 | BUG_ON(ni->type != AT_DATA); | ||
527 | BUG_ON(ni->name_len); | ||
528 | |||
529 | pages = kmalloc(nr_pages * sizeof(struct page *), GFP_NOFS); | ||
530 | |||
531 | /* Allocate memory to store the buffer heads we need. */ | ||
532 | bhs_size = cb_size / block_size * sizeof(struct buffer_head *); | ||
533 | bhs = kmalloc(bhs_size, GFP_NOFS); | ||
534 | |||
535 | if (unlikely(!pages || !bhs)) { | ||
536 | kfree(bhs); | ||
537 | kfree(pages); | ||
538 | SetPageError(page); | ||
539 | unlock_page(page); | ||
540 | ntfs_error(vol->sb, "Failed to allocate internal buffers."); | ||
541 | return -ENOMEM; | ||
542 | } | ||
543 | |||
544 | /* | ||
545 | * We have already been given one page, this is the one we must do. | ||
546 | * Once again, the alignment guarantees keep it simple. | ||
547 | */ | ||
548 | offset = start_vcn << vol->cluster_size_bits >> PAGE_CACHE_SHIFT; | ||
549 | xpage = index - offset; | ||
550 | pages[xpage] = page; | ||
551 | /* | ||
552 | * The remaining pages need to be allocated and inserted into the page | ||
553 | * cache, alignment guarantees keep all the below much simpler. (-8 | ||
554 | */ | ||
555 | max_page = ((VFS_I(ni)->i_size + PAGE_CACHE_SIZE - 1) >> | ||
556 | PAGE_CACHE_SHIFT) - offset; | ||
557 | if (nr_pages < max_page) | ||
558 | max_page = nr_pages; | ||
559 | for (i = 0; i < max_page; i++, offset++) { | ||
560 | if (i != xpage) | ||
561 | pages[i] = grab_cache_page_nowait(mapping, offset); | ||
562 | page = pages[i]; | ||
563 | if (page) { | ||
564 | /* | ||
565 | * We only (re)read the page if it isn't already read | ||
566 | * in and/or dirty or we would be losing data or at | ||
567 | * least wasting our time. | ||
568 | */ | ||
569 | if (!PageDirty(page) && (!PageUptodate(page) || | ||
570 | PageError(page))) { | ||
571 | ClearPageError(page); | ||
572 | kmap(page); | ||
573 | continue; | ||
574 | } | ||
575 | unlock_page(page); | ||
576 | page_cache_release(page); | ||
577 | pages[i] = NULL; | ||
578 | } | ||
579 | } | ||
580 | |||
581 | /* | ||
582 | * We have the runlist, and all the destination pages we need to fill. | ||
583 | * Now read the first compression block. | ||
584 | */ | ||
585 | cur_page = 0; | ||
586 | cur_ofs = 0; | ||
587 | cb_clusters = ni->itype.compressed.block_clusters; | ||
588 | do_next_cb: | ||
589 | nr_cbs--; | ||
590 | nr_bhs = 0; | ||
591 | |||
592 | /* Read all cb buffer heads one cluster at a time. */ | ||
593 | rl = NULL; | ||
594 | for (vcn = start_vcn, start_vcn += cb_clusters; vcn < start_vcn; | ||
595 | vcn++) { | ||
596 | BOOL is_retry = FALSE; | ||
597 | |||
598 | if (!rl) { | ||
599 | lock_retry_remap: | ||
600 | down_read(&ni->runlist.lock); | ||
601 | rl = ni->runlist.rl; | ||
602 | } | ||
603 | if (likely(rl != NULL)) { | ||
604 | /* Seek to element containing target vcn. */ | ||
605 | while (rl->length && rl[1].vcn <= vcn) | ||
606 | rl++; | ||
607 | lcn = ntfs_rl_vcn_to_lcn(rl, vcn); | ||
608 | } else | ||
609 | lcn = LCN_RL_NOT_MAPPED; | ||
610 | ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.", | ||
611 | (unsigned long long)vcn, | ||
612 | (unsigned long long)lcn); | ||
613 | if (lcn < 0) { | ||
614 | /* | ||
615 | * When we reach the first sparse cluster we have | ||
616 | * finished with the cb. | ||
617 | */ | ||
618 | if (lcn == LCN_HOLE) | ||
619 | break; | ||
620 | if (is_retry || lcn != LCN_RL_NOT_MAPPED) | ||
621 | goto rl_err; | ||
622 | is_retry = TRUE; | ||
623 | /* | ||
624 | * Attempt to map runlist, dropping lock for the | ||
625 | * duration. | ||
626 | */ | ||
627 | up_read(&ni->runlist.lock); | ||
628 | if (!ntfs_map_runlist(ni, vcn)) | ||
629 | goto lock_retry_remap; | ||
630 | goto map_rl_err; | ||
631 | } | ||
632 | block = lcn << vol->cluster_size_bits >> block_size_bits; | ||
633 | /* Read the lcn from device in chunks of block_size bytes. */ | ||
634 | max_block = block + (vol->cluster_size >> block_size_bits); | ||
635 | do { | ||
636 | ntfs_debug("block = 0x%x.", block); | ||
637 | if (unlikely(!(bhs[nr_bhs] = sb_getblk(sb, block)))) | ||
638 | goto getblk_err; | ||
639 | nr_bhs++; | ||
640 | } while (++block < max_block); | ||
641 | } | ||
642 | |||
643 | /* Release the lock if we took it. */ | ||
644 | if (rl) | ||
645 | up_read(&ni->runlist.lock); | ||
646 | |||
647 | /* Setup and initiate io on all buffer heads. */ | ||
648 | for (i = 0; i < nr_bhs; i++) { | ||
649 | struct buffer_head *tbh = bhs[i]; | ||
650 | |||
651 | if (unlikely(test_set_buffer_locked(tbh))) | ||
652 | continue; | ||
653 | if (unlikely(buffer_uptodate(tbh))) { | ||
654 | unlock_buffer(tbh); | ||
655 | continue; | ||
656 | } | ||
657 | get_bh(tbh); | ||
658 | tbh->b_end_io = end_buffer_read_sync; | ||
659 | submit_bh(READ, tbh); | ||
660 | } | ||
661 | |||
662 | /* Wait for io completion on all buffer heads. */ | ||
663 | for (i = 0; i < nr_bhs; i++) { | ||
664 | struct buffer_head *tbh = bhs[i]; | ||
665 | |||
666 | if (buffer_uptodate(tbh)) | ||
667 | continue; | ||
668 | wait_on_buffer(tbh); | ||
669 | /* | ||
670 | * We need an optimization barrier here, otherwise we start | ||
671 | * hitting the below fixup code when accessing a loopback | ||
672 | * mounted ntfs partition. This indicates either there is a | ||
673 | * race condition in the loop driver or, more likely, gcc | ||
674 | * overoptimises the code without the barrier and it doesn't | ||
675 | * do the Right Thing(TM). | ||
676 | */ | ||
677 | barrier(); | ||
678 | if (unlikely(!buffer_uptodate(tbh))) { | ||
679 | ntfs_warning(vol->sb, "Buffer is unlocked but not " | ||
680 | "uptodate! Unplugging the disk queue " | ||
681 | "and rescheduling."); | ||
682 | get_bh(tbh); | ||
683 | blk_run_address_space(mapping); | ||
684 | schedule(); | ||
685 | put_bh(tbh); | ||
686 | if (unlikely(!buffer_uptodate(tbh))) | ||
687 | goto read_err; | ||
688 | ntfs_warning(vol->sb, "Buffer is now uptodate. Good."); | ||
689 | } | ||
690 | } | ||
691 | |||
692 | /* | ||
693 | * Get the compression buffer. We must not sleep any more | ||
694 | * until we are finished with it. | ||
695 | */ | ||
696 | spin_lock(&ntfs_cb_lock); | ||
697 | cb = ntfs_compression_buffer; | ||
698 | |||
699 | BUG_ON(!cb); | ||
700 | |||
701 | cb_pos = cb; | ||
702 | cb_end = cb + cb_size; | ||
703 | |||
704 | /* Copy the buffer heads into the contiguous buffer. */ | ||
705 | for (i = 0; i < nr_bhs; i++) { | ||
706 | memcpy(cb_pos, bhs[i]->b_data, block_size); | ||
707 | cb_pos += block_size; | ||
708 | } | ||
709 | |||
710 | /* Just a precaution. */ | ||
711 | if (cb_pos + 2 <= cb + cb_size) | ||
712 | *(u16*)cb_pos = 0; | ||
713 | |||
714 | /* Reset cb_pos back to the beginning. */ | ||
715 | cb_pos = cb; | ||
716 | |||
717 | /* We now have both source (if present) and destination. */ | ||
718 | ntfs_debug("Successfully read the compression block."); | ||
719 | |||
720 | /* The last page and maximum offset within it for the current cb. */ | ||
721 | cb_max_page = (cur_page << PAGE_CACHE_SHIFT) + cur_ofs + cb_size; | ||
722 | cb_max_ofs = cb_max_page & ~PAGE_CACHE_MASK; | ||
723 | cb_max_page >>= PAGE_CACHE_SHIFT; | ||
724 | |||
725 | /* Catch end of file inside a compression block. */ | ||
726 | if (cb_max_page > max_page) | ||
727 | cb_max_page = max_page; | ||
728 | |||
729 | if (vcn == start_vcn - cb_clusters) { | ||
730 | /* Sparse cb, zero out page range overlapping the cb. */ | ||
731 | ntfs_debug("Found sparse compression block."); | ||
732 | /* We can sleep from now on, so we drop lock. */ | ||
733 | spin_unlock(&ntfs_cb_lock); | ||
734 | if (cb_max_ofs) | ||
735 | cb_max_page--; | ||
736 | for (; cur_page < cb_max_page; cur_page++) { | ||
737 | page = pages[cur_page]; | ||
738 | if (page) { | ||
739 | /* | ||
740 | * FIXME: Using clear_page() will become wrong | ||
741 | * when we get PAGE_CACHE_SIZE != PAGE_SIZE but | ||
742 | * for now there is no problem. | ||
743 | */ | ||
744 | if (likely(!cur_ofs)) | ||
745 | clear_page(page_address(page)); | ||
746 | else | ||
747 | memset(page_address(page) + cur_ofs, 0, | ||
748 | PAGE_CACHE_SIZE - | ||
749 | cur_ofs); | ||
750 | flush_dcache_page(page); | ||
751 | kunmap(page); | ||
752 | SetPageUptodate(page); | ||
753 | unlock_page(page); | ||
754 | if (cur_page == xpage) | ||
755 | xpage_done = 1; | ||
756 | else | ||
757 | page_cache_release(page); | ||
758 | pages[cur_page] = NULL; | ||
759 | } | ||
760 | cb_pos += PAGE_CACHE_SIZE - cur_ofs; | ||
761 | cur_ofs = 0; | ||
762 | if (cb_pos >= cb_end) | ||
763 | break; | ||
764 | } | ||
765 | /* If we have a partial final page, deal with it now. */ | ||
766 | if (cb_max_ofs && cb_pos < cb_end) { | ||
767 | page = pages[cur_page]; | ||
768 | if (page) | ||
769 | memset(page_address(page) + cur_ofs, 0, | ||
770 | cb_max_ofs - cur_ofs); | ||
771 | /* | ||
772 | * No need to update cb_pos at this stage: | ||
773 | * cb_pos += cb_max_ofs - cur_ofs; | ||
774 | */ | ||
775 | cur_ofs = cb_max_ofs; | ||
776 | } | ||
777 | } else if (vcn == start_vcn) { | ||
778 | /* We can't sleep so we need two stages. */ | ||
779 | unsigned int cur2_page = cur_page; | ||
780 | unsigned int cur_ofs2 = cur_ofs; | ||
781 | u8 *cb_pos2 = cb_pos; | ||
782 | |||
783 | ntfs_debug("Found uncompressed compression block."); | ||
784 | /* Uncompressed cb, copy it to the destination pages. */ | ||
785 | /* | ||
786 | * TODO: As a big optimization, we could detect this case | ||
787 | * before we read all the pages and use block_read_full_page() | ||
788 | * on all full pages instead (we still have to treat partial | ||
789 | * pages especially but at least we are getting rid of the | ||
790 | * synchronous io for the majority of pages. | ||
791 | * Or if we choose not to do the read-ahead/-behind stuff, we | ||
792 | * could just return block_read_full_page(pages[xpage]) as long | ||
793 | * as PAGE_CACHE_SIZE <= cb_size. | ||
794 | */ | ||
795 | if (cb_max_ofs) | ||
796 | cb_max_page--; | ||
797 | /* First stage: copy data into destination pages. */ | ||
798 | for (; cur_page < cb_max_page; cur_page++) { | ||
799 | page = pages[cur_page]; | ||
800 | if (page) | ||
801 | memcpy(page_address(page) + cur_ofs, cb_pos, | ||
802 | PAGE_CACHE_SIZE - cur_ofs); | ||
803 | cb_pos += PAGE_CACHE_SIZE - cur_ofs; | ||
804 | cur_ofs = 0; | ||
805 | if (cb_pos >= cb_end) | ||
806 | break; | ||
807 | } | ||
808 | /* If we have a partial final page, deal with it now. */ | ||
809 | if (cb_max_ofs && cb_pos < cb_end) { | ||
810 | page = pages[cur_page]; | ||
811 | if (page) | ||
812 | memcpy(page_address(page) + cur_ofs, cb_pos, | ||
813 | cb_max_ofs - cur_ofs); | ||
814 | cb_pos += cb_max_ofs - cur_ofs; | ||
815 | cur_ofs = cb_max_ofs; | ||
816 | } | ||
817 | /* We can sleep from now on, so drop lock. */ | ||
818 | spin_unlock(&ntfs_cb_lock); | ||
819 | /* Second stage: finalize pages. */ | ||
820 | for (; cur2_page < cb_max_page; cur2_page++) { | ||
821 | page = pages[cur2_page]; | ||
822 | if (page) { | ||
823 | /* | ||
824 | * If we are outside the initialized size, zero | ||
825 | * the out of bounds page range. | ||
826 | */ | ||
827 | handle_bounds_compressed_page(ni, page); | ||
828 | flush_dcache_page(page); | ||
829 | kunmap(page); | ||
830 | SetPageUptodate(page); | ||
831 | unlock_page(page); | ||
832 | if (cur2_page == xpage) | ||
833 | xpage_done = 1; | ||
834 | else | ||
835 | page_cache_release(page); | ||
836 | pages[cur2_page] = NULL; | ||
837 | } | ||
838 | cb_pos2 += PAGE_CACHE_SIZE - cur_ofs2; | ||
839 | cur_ofs2 = 0; | ||
840 | if (cb_pos2 >= cb_end) | ||
841 | break; | ||
842 | } | ||
843 | } else { | ||
844 | /* Compressed cb, decompress it into the destination page(s). */ | ||
845 | unsigned int prev_cur_page = cur_page; | ||
846 | |||
847 | ntfs_debug("Found compressed compression block."); | ||
848 | err = ntfs_decompress(pages, &cur_page, &cur_ofs, | ||
849 | cb_max_page, cb_max_ofs, xpage, &xpage_done, | ||
850 | cb_pos, cb_size - (cb_pos - cb)); | ||
851 | /* | ||
852 | * We can sleep from now on, lock already dropped by | ||
853 | * ntfs_decompress(). | ||
854 | */ | ||
855 | if (err) { | ||
856 | ntfs_error(vol->sb, "ntfs_decompress() failed in inode " | ||
857 | "0x%lx with error code %i. Skipping " | ||
858 | "this compression block.", | ||
859 | ni->mft_no, -err); | ||
860 | /* Release the unfinished pages. */ | ||
861 | for (; prev_cur_page < cur_page; prev_cur_page++) { | ||
862 | page = pages[prev_cur_page]; | ||
863 | if (page) { | ||
864 | if (prev_cur_page == xpage && | ||
865 | !xpage_done) | ||
866 | SetPageError(page); | ||
867 | flush_dcache_page(page); | ||
868 | kunmap(page); | ||
869 | unlock_page(page); | ||
870 | if (prev_cur_page != xpage) | ||
871 | page_cache_release(page); | ||
872 | pages[prev_cur_page] = NULL; | ||
873 | } | ||
874 | } | ||
875 | } | ||
876 | } | ||
877 | |||
878 | /* Release the buffer heads. */ | ||
879 | for (i = 0; i < nr_bhs; i++) | ||
880 | brelse(bhs[i]); | ||
881 | |||
882 | /* Do we have more work to do? */ | ||
883 | if (nr_cbs) | ||
884 | goto do_next_cb; | ||
885 | |||
886 | /* We no longer need the list of buffer heads. */ | ||
887 | kfree(bhs); | ||
888 | |||
889 | /* Clean up if we have any pages left. Should never happen. */ | ||
890 | for (cur_page = 0; cur_page < max_page; cur_page++) { | ||
891 | page = pages[cur_page]; | ||
892 | if (page) { | ||
893 | ntfs_error(vol->sb, "Still have pages left! " | ||
894 | "Terminating them with extreme " | ||
895 | "prejudice. Inode 0x%lx, page index " | ||
896 | "0x%lx.", ni->mft_no, page->index); | ||
897 | if (cur_page == xpage && !xpage_done) | ||
898 | SetPageError(page); | ||
899 | flush_dcache_page(page); | ||
900 | kunmap(page); | ||
901 | unlock_page(page); | ||
902 | if (cur_page != xpage) | ||
903 | page_cache_release(page); | ||
904 | pages[cur_page] = NULL; | ||
905 | } | ||
906 | } | ||
907 | |||
908 | /* We no longer need the list of pages. */ | ||
909 | kfree(pages); | ||
910 | |||
911 | /* If we have completed the requested page, we return success. */ | ||
912 | if (likely(xpage_done)) | ||
913 | return 0; | ||
914 | |||
915 | ntfs_debug("Failed. Returning error code %s.", err == -EOVERFLOW ? | ||
916 | "EOVERFLOW" : (!err ? "EIO" : "unkown error")); | ||
917 | return err < 0 ? err : -EIO; | ||
918 | |||
919 | read_err: | ||
920 | ntfs_error(vol->sb, "IO error while reading compressed data."); | ||
921 | /* Release the buffer heads. */ | ||
922 | for (i = 0; i < nr_bhs; i++) | ||
923 | brelse(bhs[i]); | ||
924 | goto err_out; | ||
925 | |||
926 | map_rl_err: | ||
927 | ntfs_error(vol->sb, "ntfs_map_runlist() failed. Cannot read " | ||
928 | "compression block."); | ||
929 | goto err_out; | ||
930 | |||
931 | rl_err: | ||
932 | up_read(&ni->runlist.lock); | ||
933 | ntfs_error(vol->sb, "ntfs_rl_vcn_to_lcn() failed. Cannot read " | ||
934 | "compression block."); | ||
935 | goto err_out; | ||
936 | |||
937 | getblk_err: | ||
938 | up_read(&ni->runlist.lock); | ||
939 | ntfs_error(vol->sb, "getblk() failed. Cannot read compression block."); | ||
940 | |||
941 | err_out: | ||
942 | kfree(bhs); | ||
943 | for (i = cur_page; i < max_page; i++) { | ||
944 | page = pages[i]; | ||
945 | if (page) { | ||
946 | if (i == xpage && !xpage_done) | ||
947 | SetPageError(page); | ||
948 | flush_dcache_page(page); | ||
949 | kunmap(page); | ||
950 | unlock_page(page); | ||
951 | if (i != xpage) | ||
952 | page_cache_release(page); | ||
953 | } | ||
954 | } | ||
955 | kfree(pages); | ||
956 | return -EIO; | ||
957 | } | ||