blob: ee4144ce5d7cab3ac400a0fe39f0120e3df6d15b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/**
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090028#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
30#include "attrib.h"
31#include "inode.h"
32#include "debug.h"
33#include "ntfs.h"
34
35/**
36 * ntfs_compression_constants - enum of constants used in the compression code
37 */
38typedef enum {
39 /* Token types and access mask. */
40 NTFS_SYMBOL_TOKEN = 0,
41 NTFS_PHRASE_TOKEN = 1,
42 NTFS_TOKEN_MASK = 1,
43
44 /* Compression sub-block constants. */
45 NTFS_SB_SIZE_MASK = 0x0fff,
46 NTFS_SB_SIZE = 0x1000,
47 NTFS_SB_IS_COMPRESSED = 0x8000,
48
49 /*
50 * The maximum compression block size is by definition 16 * the cluster
51 * size, with the maximum supported cluster size being 4kiB. Thus the
52 * maximum compression buffer size is 64kiB, so we use this when
53 * initializing the compression buffer.
54 */
55 NTFS_MAX_CB_SIZE = 64 * 1024,
56} ntfs_compression_constants;
57
58/**
59 * ntfs_compression_buffer - one buffer for the decompression engine
60 */
61static u8 *ntfs_compression_buffer = NULL;
62
63/**
64 * ntfs_cb_lock - spinlock which protects ntfs_compression_buffer
65 */
66static DEFINE_SPINLOCK(ntfs_cb_lock);
67
68/**
69 * allocate_compression_buffers - allocate the decompression buffers
70 *
Ingo Molnar4e5e5292006-03-23 16:57:48 +000071 * Caller has to hold the ntfs_lock mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 *
73 * Return 0 on success or -ENOMEM if the allocations failed.
74 */
75int allocate_compression_buffers(void)
76{
77 BUG_ON(ntfs_compression_buffer);
78
79 ntfs_compression_buffer = vmalloc(NTFS_MAX_CB_SIZE);
80 if (!ntfs_compression_buffer)
81 return -ENOMEM;
82 return 0;
83}
84
85/**
86 * free_compression_buffers - free the decompression buffers
87 *
Ingo Molnar4e5e5292006-03-23 16:57:48 +000088 * Caller has to hold the ntfs_lock mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 */
90void free_compression_buffers(void)
91{
92 BUG_ON(!ntfs_compression_buffer);
93 vfree(ntfs_compression_buffer);
94 ntfs_compression_buffer = NULL;
95}
96
97/**
98 * zero_partial_compressed_page - zero out of bounds compressed page region
99 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000100static void zero_partial_compressed_page(struct page *page,
101 const s64 initialized_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102{
103 u8 *kp = page_address(page);
104 unsigned int kp_ofs;
105
106 ntfs_debug("Zeroing page region outside initialized size.");
Anton Altaparmakov36763672004-11-18 13:46:45 +0000107 if (((s64)page->index << PAGE_CACHE_SHIFT) >= initialized_size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 /*
109 * FIXME: Using clear_page() will become wrong when we get
110 * PAGE_CACHE_SIZE != PAGE_SIZE but for now there is no problem.
111 */
112 clear_page(kp);
113 return;
114 }
Anton Altaparmakov36763672004-11-18 13:46:45 +0000115 kp_ofs = initialized_size & ~PAGE_CACHE_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 memset(kp + kp_ofs, 0, PAGE_CACHE_SIZE - kp_ofs);
117 return;
118}
119
120/**
121 * handle_bounds_compressed_page - test for&handle out of bounds compressed page
122 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000123static inline void handle_bounds_compressed_page(struct page *page,
124 const loff_t i_size, const s64 initialized_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125{
Anton Altaparmakov36763672004-11-18 13:46:45 +0000126 if ((page->index >= (initialized_size >> PAGE_CACHE_SHIFT)) &&
127 (initialized_size < i_size))
128 zero_partial_compressed_page(page, initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 return;
130}
131
132/**
133 * ntfs_decompress - decompress a compression block into an array of pages
134 * @dest_pages: destination array of pages
135 * @dest_index: current index into @dest_pages (IN/OUT)
136 * @dest_ofs: current offset within @dest_pages[@dest_index] (IN/OUT)
137 * @dest_max_index: maximum index into @dest_pages (IN)
138 * @dest_max_ofs: maximum offset within @dest_pages[@dest_max_index] (IN)
139 * @xpage: the target page (-1 if none) (IN)
140 * @xpage_done: set to 1 if xpage was completed successfully (IN/OUT)
141 * @cb_start: compression block to decompress (IN)
142 * @cb_size: size of compression block @cb_start in bytes (IN)
Anton Altaparmakov36763672004-11-18 13:46:45 +0000143 * @i_size: file size when we started the read (IN)
144 * @initialized_size: initialized file size when we started the read (IN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 *
146 * The caller must have disabled preemption. ntfs_decompress() reenables it when
147 * the critical section is finished.
148 *
149 * This decompresses the compression block @cb_start into the array of
150 * destination pages @dest_pages starting at index @dest_index into @dest_pages
151 * and at offset @dest_pos into the page @dest_pages[@dest_index].
152 *
153 * When the page @dest_pages[@xpage] is completed, @xpage_done is set to 1.
154 * If xpage is -1 or @xpage has not been completed, @xpage_done is not modified.
155 *
156 * @cb_start is a pointer to the compression block which needs decompressing
157 * and @cb_size is the size of @cb_start in bytes (8-64kiB).
158 *
159 * Return 0 if success or -EOVERFLOW on error in the compressed stream.
160 * @xpage_done indicates whether the target page (@dest_pages[@xpage]) was
161 * completed during the decompression of the compression block (@cb_start).
162 *
163 * Warning: This function *REQUIRES* PAGE_CACHE_SIZE >= 4096 or it will blow up
164 * unpredicatbly! You have been warned!
165 *
166 * Note to hackers: This function may not sleep until it has finished accessing
167 * the compression block @cb_start as it is a per-CPU buffer.
168 */
169static int ntfs_decompress(struct page *dest_pages[], int *dest_index,
170 int *dest_ofs, const int dest_max_index, const int dest_max_ofs,
171 const int xpage, char *xpage_done, u8 *const cb_start,
Anton Altaparmakov36763672004-11-18 13:46:45 +0000172 const u32 cb_size, const loff_t i_size,
173 const s64 initialized_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174{
175 /*
176 * Pointers into the compressed data, i.e. the compression block (cb),
177 * and the therein contained sub-blocks (sb).
178 */
179 u8 *cb_end = cb_start + cb_size; /* End of cb. */
180 u8 *cb = cb_start; /* Current position in cb. */
181 u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */
182 u8 *cb_sb_end; /* End of current sb / beginning of next sb. */
183
184 /* Variables for uncompressed data / destination. */
185 struct page *dp; /* Current destination page being worked on. */
186 u8 *dp_addr; /* Current pointer into dp. */
187 u8 *dp_sb_start; /* Start of current sub-block in dp. */
188 u8 *dp_sb_end; /* End of current sb in dp (dp_sb_start +
189 NTFS_SB_SIZE). */
190 u16 do_sb_start; /* @dest_ofs when starting this sub-block. */
191 u16 do_sb_end; /* @dest_ofs of end of this sb (do_sb_start +
192 NTFS_SB_SIZE). */
193
194 /* Variables for tag and token parsing. */
195 u8 tag; /* Current tag. */
196 int token; /* Loop counter for the eight tokens in tag. */
197
198 /* Need this because we can't sleep, so need two stages. */
199 int completed_pages[dest_max_index - *dest_index + 1];
200 int nr_completed_pages = 0;
201
202 /* Default error code. */
203 int err = -EOVERFLOW;
204
205 ntfs_debug("Entering, cb_size = 0x%x.", cb_size);
206do_next_sb:
207 ntfs_debug("Beginning sub-block at offset = 0x%zx in the cb.",
208 cb - cb_start);
209 /*
210 * Have we reached the end of the compression block or the end of the
211 * decompressed data? The latter can happen for example if the current
212 * position in the compression block is one byte before its end so the
213 * first two checks do not detect it.
214 */
215 if (cb == cb_end || !le16_to_cpup((le16*)cb) ||
216 (*dest_index == dest_max_index &&
217 *dest_ofs == dest_max_ofs)) {
218 int i;
219
220 ntfs_debug("Completed. Returning success (0).");
221 err = 0;
222return_error:
223 /* We can sleep from now on, so we drop lock. */
224 spin_unlock(&ntfs_cb_lock);
225 /* Second stage: finalize completed pages. */
226 if (nr_completed_pages > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 for (i = 0; i < nr_completed_pages; i++) {
228 int di = completed_pages[i];
229
230 dp = dest_pages[di];
231 /*
232 * If we are outside the initialized size, zero
233 * the out of bounds page range.
234 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000235 handle_bounds_compressed_page(dp, i_size,
236 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 flush_dcache_page(dp);
238 kunmap(dp);
239 SetPageUptodate(dp);
240 unlock_page(dp);
241 if (di == xpage)
242 *xpage_done = 1;
243 else
244 page_cache_release(dp);
245 dest_pages[di] = NULL;
246 }
247 }
248 return err;
249 }
250
251 /* Setup offsets for the current sub-block destination. */
252 do_sb_start = *dest_ofs;
253 do_sb_end = do_sb_start + NTFS_SB_SIZE;
254
255 /* Check that we are still within allowed boundaries. */
256 if (*dest_index == dest_max_index && do_sb_end > dest_max_ofs)
257 goto return_overflow;
258
259 /* Does the minimum size of a compressed sb overflow valid range? */
260 if (cb + 6 > cb_end)
261 goto return_overflow;
262
263 /* Setup the current sub-block source pointers and validate range. */
264 cb_sb_start = cb;
265 cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK)
266 + 3;
267 if (cb_sb_end > cb_end)
268 goto return_overflow;
269
270 /* Get the current destination page. */
271 dp = dest_pages[*dest_index];
272 if (!dp) {
273 /* No page present. Skip decompression of this sub-block. */
274 cb = cb_sb_end;
275
276 /* Advance destination position to next sub-block. */
277 *dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_CACHE_MASK;
278 if (!*dest_ofs && (++*dest_index > dest_max_index))
279 goto return_overflow;
280 goto do_next_sb;
281 }
282
283 /* We have a valid destination page. Setup the destination pointers. */
284 dp_addr = (u8*)page_address(dp) + do_sb_start;
285
286 /* Now, we are ready to process the current sub-block (sb). */
287 if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) {
288 ntfs_debug("Found uncompressed sub-block.");
289 /* This sb is not compressed, just copy it into destination. */
290
291 /* Advance source position to first data byte. */
292 cb += 2;
293
294 /* An uncompressed sb must be full size. */
295 if (cb_sb_end - cb != NTFS_SB_SIZE)
296 goto return_overflow;
297
298 /* Copy the block and advance the source position. */
299 memcpy(dp_addr, cb, NTFS_SB_SIZE);
300 cb += NTFS_SB_SIZE;
301
302 /* Advance destination position to next sub-block. */
303 *dest_ofs += NTFS_SB_SIZE;
304 if (!(*dest_ofs &= ~PAGE_CACHE_MASK)) {
305finalize_page:
306 /*
307 * First stage: add current page index to array of
308 * completed pages.
309 */
310 completed_pages[nr_completed_pages++] = *dest_index;
311 if (++*dest_index > dest_max_index)
312 goto return_overflow;
313 }
314 goto do_next_sb;
315 }
316 ntfs_debug("Found compressed sub-block.");
317 /* This sb is compressed, decompress it into destination. */
318
319 /* Setup destination pointers. */
320 dp_sb_start = dp_addr;
321 dp_sb_end = dp_sb_start + NTFS_SB_SIZE;
322
323 /* Forward to the first tag in the sub-block. */
324 cb += 2;
325do_next_tag:
326 if (cb == cb_sb_end) {
327 /* Check if the decompressed sub-block was not full-length. */
328 if (dp_addr < dp_sb_end) {
329 int nr_bytes = do_sb_end - *dest_ofs;
330
331 ntfs_debug("Filling incomplete sub-block with "
332 "zeroes.");
333 /* Zero remainder and update destination position. */
334 memset(dp_addr, 0, nr_bytes);
335 *dest_ofs += nr_bytes;
336 }
337 /* We have finished the current sub-block. */
338 if (!(*dest_ofs &= ~PAGE_CACHE_MASK))
339 goto finalize_page;
340 goto do_next_sb;
341 }
342
343 /* Check we are still in range. */
344 if (cb > cb_sb_end || dp_addr > dp_sb_end)
345 goto return_overflow;
346
347 /* Get the next tag and advance to first token. */
348 tag = *cb++;
349
350 /* Parse the eight tokens described by the tag. */
351 for (token = 0; token < 8; token++, tag >>= 1) {
352 u16 lg, pt, length, max_non_overlap;
353 register u16 i;
354 u8 *dp_back_addr;
355
356 /* Check if we are done / still in range. */
357 if (cb >= cb_sb_end || dp_addr > dp_sb_end)
358 break;
359
360 /* Determine token type and parse appropriately.*/
361 if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) {
362 /*
363 * We have a symbol token, copy the symbol across, and
364 * advance the source and destination positions.
365 */
366 *dp_addr++ = *cb++;
367 ++*dest_ofs;
368
369 /* Continue with the next token. */
370 continue;
371 }
372
373 /*
374 * We have a phrase token. Make sure it is not the first tag in
375 * the sb as this is illegal and would confuse the code below.
376 */
377 if (dp_addr == dp_sb_start)
378 goto return_overflow;
379
380 /*
381 * Determine the number of bytes to go back (p) and the number
382 * of bytes to copy (l). We use an optimized algorithm in which
383 * we first calculate log2(current destination position in sb),
384 * which allows determination of l and p in O(1) rather than
385 * O(n). We just need an arch-optimized log2() function now.
386 */
387 lg = 0;
388 for (i = *dest_ofs - do_sb_start - 1; i >= 0x10; i >>= 1)
389 lg++;
390
391 /* Get the phrase token into i. */
392 pt = le16_to_cpup((le16*)cb);
393
394 /*
395 * Calculate starting position of the byte sequence in
396 * the destination using the fact that p = (pt >> (12 - lg)) + 1
397 * and make sure we don't go too far back.
398 */
399 dp_back_addr = dp_addr - (pt >> (12 - lg)) - 1;
400 if (dp_back_addr < dp_sb_start)
401 goto return_overflow;
402
403 /* Now calculate the length of the byte sequence. */
404 length = (pt & (0xfff >> lg)) + 3;
405
406 /* Advance destination position and verify it is in range. */
407 *dest_ofs += length;
408 if (*dest_ofs > do_sb_end)
409 goto return_overflow;
410
411 /* The number of non-overlapping bytes. */
412 max_non_overlap = dp_addr - dp_back_addr;
413
414 if (length <= max_non_overlap) {
415 /* The byte sequence doesn't overlap, just copy it. */
416 memcpy(dp_addr, dp_back_addr, length);
417
418 /* Advance destination pointer. */
419 dp_addr += length;
420 } else {
421 /*
422 * The byte sequence does overlap, copy non-overlapping
423 * part and then do a slow byte by byte copy for the
424 * overlapping part. Also, advance the destination
425 * pointer.
426 */
427 memcpy(dp_addr, dp_back_addr, max_non_overlap);
428 dp_addr += max_non_overlap;
429 dp_back_addr += max_non_overlap;
430 length -= max_non_overlap;
431 while (length--)
432 *dp_addr++ = *dp_back_addr++;
433 }
434
435 /* Advance source position and continue with the next token. */
436 cb += 2;
437 }
438
439 /* No tokens left in the current tag. Continue with the next tag. */
440 goto do_next_tag;
441
442return_overflow:
443 ntfs_error(NULL, "Failed. Returning -EOVERFLOW.");
444 goto return_error;
445}
446
447/**
448 * ntfs_read_compressed_block - read a compressed block into the page cache
449 * @page: locked page in the compression block(s) we need to read
450 *
451 * When we are called the page has already been verified to be locked and the
452 * attribute is known to be non-resident, not encrypted, but compressed.
453 *
454 * 1. Determine which compression block(s) @page is in.
455 * 2. Get hold of all pages corresponding to this/these compression block(s).
456 * 3. Read the (first) compression block.
457 * 4. Decompress it into the corresponding pages.
458 * 5. Throw the compressed data away and proceed to 3. for the next compression
459 * block or return success if no more compression blocks left.
460 *
461 * Warning: We have to be careful what we do about existing pages. They might
462 * have been written to so that we would lose data if we were to just overwrite
463 * them with the out-of-date uncompressed data.
464 *
465 * FIXME: For PAGE_CACHE_SIZE > cb_size we are not doing the Right Thing(TM) at
466 * the end of the file I think. We need to detect this case and zero the out
467 * of bounds remainder of the page in question and mark it as handled. At the
468 * moment we would just return -EIO on such a page. This bug will only become
469 * apparent if pages are above 8kiB and the NTFS volume only uses 512 byte
470 * clusters so is probably not going to be seen by anyone. Still this should
471 * be fixed. (AIA)
472 *
473 * FIXME: Again for PAGE_CACHE_SIZE > cb_size we are screwing up both in
474 * handling sparse and compressed cbs. (AIA)
475 *
476 * FIXME: At the moment we don't do any zeroing out in the case that
477 * initialized_size is less than data_size. This should be safe because of the
478 * nature of the compression algorithm used. Just in case we check and output
479 * an error message in read inode if the two sizes are not equal for a
480 * compressed file. (AIA)
481 */
482int ntfs_read_compressed_block(struct page *page)
483{
Anton Altaparmakov36763672004-11-18 13:46:45 +0000484 loff_t i_size;
485 s64 initialized_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 struct address_space *mapping = page->mapping;
487 ntfs_inode *ni = NTFS_I(mapping->host);
488 ntfs_volume *vol = ni->vol;
489 struct super_block *sb = vol->sb;
490 runlist_element *rl;
Anton Altaparmakov36763672004-11-18 13:46:45 +0000491 unsigned long flags, block_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 unsigned char block_size_bits = sb->s_blocksize_bits;
493 u8 *cb, *cb_pos, *cb_end;
494 struct buffer_head **bhs;
495 unsigned long offset, index = page->index;
496 u32 cb_size = ni->itype.compressed.block_size;
497 u64 cb_size_mask = cb_size - 1UL;
498 VCN vcn;
499 LCN lcn;
500 /* The first wanted vcn (minimum alignment is PAGE_CACHE_SIZE). */
501 VCN start_vcn = (((s64)index << PAGE_CACHE_SHIFT) & ~cb_size_mask) >>
502 vol->cluster_size_bits;
503 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300504 * The first vcn after the last wanted vcn (minimum alignment is again
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 * PAGE_CACHE_SIZE.
506 */
507 VCN end_vcn = ((((s64)(index + 1UL) << PAGE_CACHE_SHIFT) + cb_size - 1)
508 & ~cb_size_mask) >> vol->cluster_size_bits;
509 /* Number of compression blocks (cbs) in the wanted vcn range. */
510 unsigned int nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits
511 >> ni->itype.compressed.block_size_bits;
512 /*
513 * Number of pages required to store the uncompressed data from all
514 * compression blocks (cbs) overlapping @page. Due to alignment
515 * guarantees of start_vcn and end_vcn, no need to round up here.
516 */
517 unsigned int nr_pages = (end_vcn - start_vcn) <<
518 vol->cluster_size_bits >> PAGE_CACHE_SHIFT;
519 unsigned int xpage, max_page, cur_page, cur_ofs, i;
520 unsigned int cb_clusters, cb_max_ofs;
521 int block, max_block, cb_max_page, bhs_size, nr_bhs, err = 0;
522 struct page **pages;
523 unsigned char xpage_done = 0;
524
525 ntfs_debug("Entering, page->index = 0x%lx, cb_size = 0x%x, nr_pages = "
526 "%i.", index, cb_size, nr_pages);
527 /*
528 * Bad things happen if we get here for anything that is not an
529 * unnamed $DATA attribute.
530 */
531 BUG_ON(ni->type != AT_DATA);
532 BUG_ON(ni->name_len);
533
534 pages = kmalloc(nr_pages * sizeof(struct page *), GFP_NOFS);
535
536 /* Allocate memory to store the buffer heads we need. */
537 bhs_size = cb_size / block_size * sizeof(struct buffer_head *);
538 bhs = kmalloc(bhs_size, GFP_NOFS);
539
540 if (unlikely(!pages || !bhs)) {
541 kfree(bhs);
542 kfree(pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 unlock_page(page);
544 ntfs_error(vol->sb, "Failed to allocate internal buffers.");
545 return -ENOMEM;
546 }
547
548 /*
549 * We have already been given one page, this is the one we must do.
550 * Once again, the alignment guarantees keep it simple.
551 */
552 offset = start_vcn << vol->cluster_size_bits >> PAGE_CACHE_SHIFT;
553 xpage = index - offset;
554 pages[xpage] = page;
555 /*
556 * The remaining pages need to be allocated and inserted into the page
557 * cache, alignment guarantees keep all the below much simpler. (-8
558 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000559 read_lock_irqsave(&ni->size_lock, flags);
560 i_size = i_size_read(VFS_I(ni));
561 initialized_size = ni->initialized_size;
562 read_unlock_irqrestore(&ni->size_lock, flags);
563 max_page = ((i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
564 offset;
Anton Altaparmakovebab8992007-11-03 07:38:59 +0000565 /* Is the page fully outside i_size? (truncate in progress) */
566 if (xpage >= max_page) {
567 kfree(bhs);
568 kfree(pages);
Christoph Lametereebd2aa2008-02-04 22:28:29 -0800569 zero_user(page, 0, PAGE_CACHE_SIZE);
Anton Altaparmakovebab8992007-11-03 07:38:59 +0000570 ntfs_debug("Compressed read outside i_size - truncated?");
571 SetPageUptodate(page);
572 unlock_page(page);
573 return 0;
574 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 if (nr_pages < max_page)
576 max_page = nr_pages;
577 for (i = 0; i < max_page; i++, offset++) {
578 if (i != xpage)
579 pages[i] = grab_cache_page_nowait(mapping, offset);
580 page = pages[i];
581 if (page) {
582 /*
583 * We only (re)read the page if it isn't already read
584 * in and/or dirty or we would be losing data or at
585 * least wasting our time.
586 */
587 if (!PageDirty(page) && (!PageUptodate(page) ||
588 PageError(page))) {
589 ClearPageError(page);
590 kmap(page);
591 continue;
592 }
593 unlock_page(page);
594 page_cache_release(page);
595 pages[i] = NULL;
596 }
597 }
598
599 /*
600 * We have the runlist, and all the destination pages we need to fill.
601 * Now read the first compression block.
602 */
603 cur_page = 0;
604 cur_ofs = 0;
605 cb_clusters = ni->itype.compressed.block_clusters;
606do_next_cb:
607 nr_cbs--;
608 nr_bhs = 0;
609
610 /* Read all cb buffer heads one cluster at a time. */
611 rl = NULL;
612 for (vcn = start_vcn, start_vcn += cb_clusters; vcn < start_vcn;
613 vcn++) {
Richard Knutssonc49c3112006-09-30 23:27:12 -0700614 bool is_retry = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
616 if (!rl) {
617lock_retry_remap:
618 down_read(&ni->runlist.lock);
619 rl = ni->runlist.rl;
620 }
621 if (likely(rl != NULL)) {
622 /* Seek to element containing target vcn. */
623 while (rl->length && rl[1].vcn <= vcn)
624 rl++;
625 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
626 } else
627 lcn = LCN_RL_NOT_MAPPED;
628 ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
629 (unsigned long long)vcn,
630 (unsigned long long)lcn);
631 if (lcn < 0) {
632 /*
633 * When we reach the first sparse cluster we have
634 * finished with the cb.
635 */
636 if (lcn == LCN_HOLE)
637 break;
638 if (is_retry || lcn != LCN_RL_NOT_MAPPED)
639 goto rl_err;
Richard Knutssonc49c3112006-09-30 23:27:12 -0700640 is_retry = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 /*
642 * Attempt to map runlist, dropping lock for the
643 * duration.
644 */
645 up_read(&ni->runlist.lock);
646 if (!ntfs_map_runlist(ni, vcn))
647 goto lock_retry_remap;
648 goto map_rl_err;
649 }
650 block = lcn << vol->cluster_size_bits >> block_size_bits;
651 /* Read the lcn from device in chunks of block_size bytes. */
652 max_block = block + (vol->cluster_size >> block_size_bits);
653 do {
654 ntfs_debug("block = 0x%x.", block);
655 if (unlikely(!(bhs[nr_bhs] = sb_getblk(sb, block))))
656 goto getblk_err;
657 nr_bhs++;
658 } while (++block < max_block);
659 }
660
661 /* Release the lock if we took it. */
662 if (rl)
663 up_read(&ni->runlist.lock);
664
665 /* Setup and initiate io on all buffer heads. */
666 for (i = 0; i < nr_bhs; i++) {
667 struct buffer_head *tbh = bhs[i];
668
Nick Pigginca5de402008-08-02 12:02:13 +0200669 if (!trylock_buffer(tbh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 continue;
671 if (unlikely(buffer_uptodate(tbh))) {
672 unlock_buffer(tbh);
673 continue;
674 }
675 get_bh(tbh);
676 tbh->b_end_io = end_buffer_read_sync;
677 submit_bh(READ, tbh);
678 }
679
680 /* Wait for io completion on all buffer heads. */
681 for (i = 0; i < nr_bhs; i++) {
682 struct buffer_head *tbh = bhs[i];
683
684 if (buffer_uptodate(tbh))
685 continue;
686 wait_on_buffer(tbh);
687 /*
688 * We need an optimization barrier here, otherwise we start
689 * hitting the below fixup code when accessing a loopback
690 * mounted ntfs partition. This indicates either there is a
691 * race condition in the loop driver or, more likely, gcc
692 * overoptimises the code without the barrier and it doesn't
693 * do the Right Thing(TM).
694 */
695 barrier();
696 if (unlikely(!buffer_uptodate(tbh))) {
697 ntfs_warning(vol->sb, "Buffer is unlocked but not "
698 "uptodate! Unplugging the disk queue "
699 "and rescheduling.");
700 get_bh(tbh);
Jens Axboe7eaceac2011-03-10 08:52:07 +0100701 io_schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 put_bh(tbh);
703 if (unlikely(!buffer_uptodate(tbh)))
704 goto read_err;
705 ntfs_warning(vol->sb, "Buffer is now uptodate. Good.");
706 }
707 }
708
709 /*
710 * Get the compression buffer. We must not sleep any more
711 * until we are finished with it.
712 */
713 spin_lock(&ntfs_cb_lock);
714 cb = ntfs_compression_buffer;
715
716 BUG_ON(!cb);
717
718 cb_pos = cb;
719 cb_end = cb + cb_size;
720
721 /* Copy the buffer heads into the contiguous buffer. */
722 for (i = 0; i < nr_bhs; i++) {
723 memcpy(cb_pos, bhs[i]->b_data, block_size);
724 cb_pos += block_size;
725 }
726
727 /* Just a precaution. */
728 if (cb_pos + 2 <= cb + cb_size)
729 *(u16*)cb_pos = 0;
730
731 /* Reset cb_pos back to the beginning. */
732 cb_pos = cb;
733
734 /* We now have both source (if present) and destination. */
735 ntfs_debug("Successfully read the compression block.");
736
737 /* The last page and maximum offset within it for the current cb. */
738 cb_max_page = (cur_page << PAGE_CACHE_SHIFT) + cur_ofs + cb_size;
739 cb_max_ofs = cb_max_page & ~PAGE_CACHE_MASK;
740 cb_max_page >>= PAGE_CACHE_SHIFT;
741
742 /* Catch end of file inside a compression block. */
743 if (cb_max_page > max_page)
744 cb_max_page = max_page;
745
746 if (vcn == start_vcn - cb_clusters) {
747 /* Sparse cb, zero out page range overlapping the cb. */
748 ntfs_debug("Found sparse compression block.");
749 /* We can sleep from now on, so we drop lock. */
750 spin_unlock(&ntfs_cb_lock);
751 if (cb_max_ofs)
752 cb_max_page--;
753 for (; cur_page < cb_max_page; cur_page++) {
754 page = pages[cur_page];
755 if (page) {
756 /*
757 * FIXME: Using clear_page() will become wrong
758 * when we get PAGE_CACHE_SIZE != PAGE_SIZE but
759 * for now there is no problem.
760 */
761 if (likely(!cur_ofs))
762 clear_page(page_address(page));
763 else
764 memset(page_address(page) + cur_ofs, 0,
765 PAGE_CACHE_SIZE -
766 cur_ofs);
767 flush_dcache_page(page);
768 kunmap(page);
769 SetPageUptodate(page);
770 unlock_page(page);
771 if (cur_page == xpage)
772 xpage_done = 1;
773 else
774 page_cache_release(page);
775 pages[cur_page] = NULL;
776 }
777 cb_pos += PAGE_CACHE_SIZE - cur_ofs;
778 cur_ofs = 0;
779 if (cb_pos >= cb_end)
780 break;
781 }
782 /* If we have a partial final page, deal with it now. */
783 if (cb_max_ofs && cb_pos < cb_end) {
784 page = pages[cur_page];
785 if (page)
786 memset(page_address(page) + cur_ofs, 0,
787 cb_max_ofs - cur_ofs);
788 /*
789 * No need to update cb_pos at this stage:
790 * cb_pos += cb_max_ofs - cur_ofs;
791 */
792 cur_ofs = cb_max_ofs;
793 }
794 } else if (vcn == start_vcn) {
795 /* We can't sleep so we need two stages. */
796 unsigned int cur2_page = cur_page;
797 unsigned int cur_ofs2 = cur_ofs;
798 u8 *cb_pos2 = cb_pos;
799
800 ntfs_debug("Found uncompressed compression block.");
801 /* Uncompressed cb, copy it to the destination pages. */
802 /*
803 * TODO: As a big optimization, we could detect this case
804 * before we read all the pages and use block_read_full_page()
805 * on all full pages instead (we still have to treat partial
806 * pages especially but at least we are getting rid of the
807 * synchronous io for the majority of pages.
808 * Or if we choose not to do the read-ahead/-behind stuff, we
809 * could just return block_read_full_page(pages[xpage]) as long
810 * as PAGE_CACHE_SIZE <= cb_size.
811 */
812 if (cb_max_ofs)
813 cb_max_page--;
814 /* First stage: copy data into destination pages. */
815 for (; cur_page < cb_max_page; cur_page++) {
816 page = pages[cur_page];
817 if (page)
818 memcpy(page_address(page) + cur_ofs, cb_pos,
819 PAGE_CACHE_SIZE - cur_ofs);
820 cb_pos += PAGE_CACHE_SIZE - cur_ofs;
821 cur_ofs = 0;
822 if (cb_pos >= cb_end)
823 break;
824 }
825 /* If we have a partial final page, deal with it now. */
826 if (cb_max_ofs && cb_pos < cb_end) {
827 page = pages[cur_page];
828 if (page)
829 memcpy(page_address(page) + cur_ofs, cb_pos,
830 cb_max_ofs - cur_ofs);
831 cb_pos += cb_max_ofs - cur_ofs;
832 cur_ofs = cb_max_ofs;
833 }
834 /* We can sleep from now on, so drop lock. */
835 spin_unlock(&ntfs_cb_lock);
836 /* Second stage: finalize pages. */
837 for (; cur2_page < cb_max_page; cur2_page++) {
838 page = pages[cur2_page];
839 if (page) {
840 /*
841 * If we are outside the initialized size, zero
842 * the out of bounds page range.
843 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000844 handle_bounds_compressed_page(page, i_size,
845 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 flush_dcache_page(page);
847 kunmap(page);
848 SetPageUptodate(page);
849 unlock_page(page);
850 if (cur2_page == xpage)
851 xpage_done = 1;
852 else
853 page_cache_release(page);
854 pages[cur2_page] = NULL;
855 }
856 cb_pos2 += PAGE_CACHE_SIZE - cur_ofs2;
857 cur_ofs2 = 0;
858 if (cb_pos2 >= cb_end)
859 break;
860 }
861 } else {
862 /* Compressed cb, decompress it into the destination page(s). */
863 unsigned int prev_cur_page = cur_page;
864
865 ntfs_debug("Found compressed compression block.");
866 err = ntfs_decompress(pages, &cur_page, &cur_ofs,
867 cb_max_page, cb_max_ofs, xpage, &xpage_done,
Anton Altaparmakov36763672004-11-18 13:46:45 +0000868 cb_pos, cb_size - (cb_pos - cb), i_size,
869 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 /*
871 * We can sleep from now on, lock already dropped by
872 * ntfs_decompress().
873 */
874 if (err) {
875 ntfs_error(vol->sb, "ntfs_decompress() failed in inode "
876 "0x%lx with error code %i. Skipping "
877 "this compression block.",
878 ni->mft_no, -err);
879 /* Release the unfinished pages. */
880 for (; prev_cur_page < cur_page; prev_cur_page++) {
881 page = pages[prev_cur_page];
882 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 flush_dcache_page(page);
884 kunmap(page);
885 unlock_page(page);
886 if (prev_cur_page != xpage)
887 page_cache_release(page);
888 pages[prev_cur_page] = NULL;
889 }
890 }
891 }
892 }
893
894 /* Release the buffer heads. */
895 for (i = 0; i < nr_bhs; i++)
896 brelse(bhs[i]);
897
898 /* Do we have more work to do? */
899 if (nr_cbs)
900 goto do_next_cb;
901
902 /* We no longer need the list of buffer heads. */
903 kfree(bhs);
904
905 /* Clean up if we have any pages left. Should never happen. */
906 for (cur_page = 0; cur_page < max_page; cur_page++) {
907 page = pages[cur_page];
908 if (page) {
909 ntfs_error(vol->sb, "Still have pages left! "
910 "Terminating them with extreme "
911 "prejudice. Inode 0x%lx, page index "
912 "0x%lx.", ni->mft_no, page->index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 flush_dcache_page(page);
914 kunmap(page);
915 unlock_page(page);
916 if (cur_page != xpage)
917 page_cache_release(page);
918 pages[cur_page] = NULL;
919 }
920 }
921
922 /* We no longer need the list of pages. */
923 kfree(pages);
924
925 /* If we have completed the requested page, we return success. */
926 if (likely(xpage_done))
927 return 0;
928
929 ntfs_debug("Failed. Returning error code %s.", err == -EOVERFLOW ?
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200930 "EOVERFLOW" : (!err ? "EIO" : "unknown error"));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 return err < 0 ? err : -EIO;
932
933read_err:
934 ntfs_error(vol->sb, "IO error while reading compressed data.");
935 /* Release the buffer heads. */
936 for (i = 0; i < nr_bhs; i++)
937 brelse(bhs[i]);
938 goto err_out;
939
940map_rl_err:
941 ntfs_error(vol->sb, "ntfs_map_runlist() failed. Cannot read "
942 "compression block.");
943 goto err_out;
944
945rl_err:
946 up_read(&ni->runlist.lock);
947 ntfs_error(vol->sb, "ntfs_rl_vcn_to_lcn() failed. Cannot read "
948 "compression block.");
949 goto err_out;
950
951getblk_err:
952 up_read(&ni->runlist.lock);
953 ntfs_error(vol->sb, "getblk() failed. Cannot read compression block.");
954
955err_out:
956 kfree(bhs);
957 for (i = cur_page; i < max_page; i++) {
958 page = pages[i];
959 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960 flush_dcache_page(page);
961 kunmap(page);
962 unlock_page(page);
963 if (i != xpage)
964 page_cache_release(page);
965 }
966 }
967 kfree(pages);
968 return -EIO;
969}