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1da177e4 LT |
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 | } |