blob: f8eb04387ca4372ee8acce8d28b29c89618477ae [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 */
Fabian Frederick504e0e22014-06-04 16:05:50 -070061static u8 *ntfs_compression_buffer;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
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.");
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300107 if (((s64)page->index << PAGE_SHIFT) >= initialized_size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 clear_page(kp);
109 return;
110 }
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300111 kp_ofs = initialized_size & ~PAGE_MASK;
112 memset(kp + kp_ofs, 0, PAGE_SIZE - kp_ofs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 return;
114}
115
116/**
117 * handle_bounds_compressed_page - test for&handle out of bounds compressed page
118 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000119static inline void handle_bounds_compressed_page(struct page *page,
120 const loff_t i_size, const s64 initialized_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300122 if ((page->index >= (initialized_size >> PAGE_SHIFT)) &&
Anton Altaparmakov36763672004-11-18 13:46:45 +0000123 (initialized_size < i_size))
124 zero_partial_compressed_page(page, initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 return;
126}
127
128/**
129 * ntfs_decompress - decompress a compression block into an array of pages
130 * @dest_pages: destination array of pages
131 * @dest_index: current index into @dest_pages (IN/OUT)
132 * @dest_ofs: current offset within @dest_pages[@dest_index] (IN/OUT)
133 * @dest_max_index: maximum index into @dest_pages (IN)
134 * @dest_max_ofs: maximum offset within @dest_pages[@dest_max_index] (IN)
135 * @xpage: the target page (-1 if none) (IN)
136 * @xpage_done: set to 1 if xpage was completed successfully (IN/OUT)
137 * @cb_start: compression block to decompress (IN)
138 * @cb_size: size of compression block @cb_start in bytes (IN)
Anton Altaparmakov36763672004-11-18 13:46:45 +0000139 * @i_size: file size when we started the read (IN)
140 * @initialized_size: initialized file size when we started the read (IN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 *
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 *
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300159 * Warning: This function *REQUIRES* PAGE_SIZE >= 4096 or it will blow up
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 * 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 */
165static 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,
Anton Altaparmakov36763672004-11-18 13:46:45 +0000168 const u32 cb_size, const loff_t i_size,
169 const s64 initialized_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170{
171 /*
172 * Pointers into the compressed data, i.e. the compression block (cb),
173 * and the therein contained sub-blocks (sb).
174 */
175 u8 *cb_end = cb_start + cb_size; /* End of cb. */
176 u8 *cb = cb_start; /* Current position in cb. */
177 u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */
178 u8 *cb_sb_end; /* End of current sb / beginning of next sb. */
179
180 /* Variables for uncompressed data / destination. */
181 struct page *dp; /* Current destination page being worked on. */
182 u8 *dp_addr; /* Current pointer into dp. */
183 u8 *dp_sb_start; /* Start of current sub-block in dp. */
184 u8 *dp_sb_end; /* End of current sb in dp (dp_sb_start +
185 NTFS_SB_SIZE). */
186 u16 do_sb_start; /* @dest_ofs when starting this sub-block. */
187 u16 do_sb_end; /* @dest_ofs of end of this sb (do_sb_start +
188 NTFS_SB_SIZE). */
189
190 /* Variables for tag and token parsing. */
191 u8 tag; /* Current tag. */
192 int token; /* Loop counter for the eight tokens in tag. */
193
194 /* Need this because we can't sleep, so need two stages. */
195 int completed_pages[dest_max_index - *dest_index + 1];
196 int nr_completed_pages = 0;
197
198 /* Default error code. */
199 int err = -EOVERFLOW;
200
201 ntfs_debug("Entering, cb_size = 0x%x.", cb_size);
202do_next_sb:
203 ntfs_debug("Beginning sub-block at offset = 0x%zx in the cb.",
204 cb - cb_start);
205 /*
206 * Have we reached the end of the compression block or the end of the
207 * decompressed data? The latter can happen for example if the current
208 * position in the compression block is one byte before its end so the
209 * first two checks do not detect it.
210 */
211 if (cb == cb_end || !le16_to_cpup((le16*)cb) ||
212 (*dest_index == dest_max_index &&
213 *dest_ofs == dest_max_ofs)) {
214 int i;
215
216 ntfs_debug("Completed. Returning success (0).");
217 err = 0;
218return_error:
219 /* We can sleep from now on, so we drop lock. */
220 spin_unlock(&ntfs_cb_lock);
221 /* Second stage: finalize completed pages. */
222 if (nr_completed_pages > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 for (i = 0; i < nr_completed_pages; i++) {
224 int di = completed_pages[i];
225
226 dp = dest_pages[di];
227 /*
228 * If we are outside the initialized size, zero
229 * the out of bounds page range.
230 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000231 handle_bounds_compressed_page(dp, i_size,
232 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 flush_dcache_page(dp);
234 kunmap(dp);
235 SetPageUptodate(dp);
236 unlock_page(dp);
237 if (di == xpage)
238 *xpage_done = 1;
239 else
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300240 put_page(dp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 dest_pages[di] = NULL;
242 }
243 }
244 return err;
245 }
246
247 /* Setup offsets for the current sub-block destination. */
248 do_sb_start = *dest_ofs;
249 do_sb_end = do_sb_start + NTFS_SB_SIZE;
250
251 /* Check that we are still within allowed boundaries. */
252 if (*dest_index == dest_max_index && do_sb_end > dest_max_ofs)
253 goto return_overflow;
254
255 /* Does the minimum size of a compressed sb overflow valid range? */
256 if (cb + 6 > cb_end)
257 goto return_overflow;
258
259 /* Setup the current sub-block source pointers and validate range. */
260 cb_sb_start = cb;
261 cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK)
262 + 3;
263 if (cb_sb_end > cb_end)
264 goto return_overflow;
265
266 /* Get the current destination page. */
267 dp = dest_pages[*dest_index];
268 if (!dp) {
269 /* No page present. Skip decompression of this sub-block. */
270 cb = cb_sb_end;
271
272 /* Advance destination position to next sub-block. */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300273 *dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 if (!*dest_ofs && (++*dest_index > dest_max_index))
275 goto return_overflow;
276 goto do_next_sb;
277 }
278
279 /* We have a valid destination page. Setup the destination pointers. */
280 dp_addr = (u8*)page_address(dp) + do_sb_start;
281
282 /* Now, we are ready to process the current sub-block (sb). */
283 if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) {
284 ntfs_debug("Found uncompressed sub-block.");
285 /* This sb is not compressed, just copy it into destination. */
286
287 /* Advance source position to first data byte. */
288 cb += 2;
289
290 /* An uncompressed sb must be full size. */
291 if (cb_sb_end - cb != NTFS_SB_SIZE)
292 goto return_overflow;
293
294 /* Copy the block and advance the source position. */
295 memcpy(dp_addr, cb, NTFS_SB_SIZE);
296 cb += NTFS_SB_SIZE;
297
298 /* Advance destination position to next sub-block. */
299 *dest_ofs += NTFS_SB_SIZE;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300300 if (!(*dest_ofs &= ~PAGE_MASK)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301finalize_page:
302 /*
303 * First stage: add current page index to array of
304 * completed pages.
305 */
306 completed_pages[nr_completed_pages++] = *dest_index;
307 if (++*dest_index > dest_max_index)
308 goto return_overflow;
309 }
310 goto do_next_sb;
311 }
312 ntfs_debug("Found compressed sub-block.");
313 /* This sb is compressed, decompress it into destination. */
314
315 /* Setup destination pointers. */
316 dp_sb_start = dp_addr;
317 dp_sb_end = dp_sb_start + NTFS_SB_SIZE;
318
319 /* Forward to the first tag in the sub-block. */
320 cb += 2;
321do_next_tag:
322 if (cb == cb_sb_end) {
323 /* Check if the decompressed sub-block was not full-length. */
324 if (dp_addr < dp_sb_end) {
325 int nr_bytes = do_sb_end - *dest_ofs;
326
327 ntfs_debug("Filling incomplete sub-block with "
328 "zeroes.");
329 /* Zero remainder and update destination position. */
330 memset(dp_addr, 0, nr_bytes);
331 *dest_ofs += nr_bytes;
332 }
333 /* We have finished the current sub-block. */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300334 if (!(*dest_ofs &= ~PAGE_MASK))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 goto finalize_page;
336 goto do_next_sb;
337 }
338
339 /* Check we are still in range. */
340 if (cb > cb_sb_end || dp_addr > dp_sb_end)
341 goto return_overflow;
342
343 /* Get the next tag and advance to first token. */
344 tag = *cb++;
345
346 /* Parse the eight tokens described by the tag. */
347 for (token = 0; token < 8; token++, tag >>= 1) {
348 u16 lg, pt, length, max_non_overlap;
349 register u16 i;
350 u8 *dp_back_addr;
351
352 /* Check if we are done / still in range. */
353 if (cb >= cb_sb_end || dp_addr > dp_sb_end)
354 break;
355
356 /* Determine token type and parse appropriately.*/
357 if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) {
358 /*
359 * We have a symbol token, copy the symbol across, and
360 * advance the source and destination positions.
361 */
362 *dp_addr++ = *cb++;
363 ++*dest_ofs;
364
365 /* Continue with the next token. */
366 continue;
367 }
368
369 /*
370 * We have a phrase token. Make sure it is not the first tag in
371 * the sb as this is illegal and would confuse the code below.
372 */
373 if (dp_addr == dp_sb_start)
374 goto return_overflow;
375
376 /*
377 * Determine the number of bytes to go back (p) and the number
378 * of bytes to copy (l). We use an optimized algorithm in which
379 * we first calculate log2(current destination position in sb),
380 * which allows determination of l and p in O(1) rather than
381 * O(n). We just need an arch-optimized log2() function now.
382 */
383 lg = 0;
384 for (i = *dest_ofs - do_sb_start - 1; i >= 0x10; i >>= 1)
385 lg++;
386
387 /* Get the phrase token into i. */
388 pt = le16_to_cpup((le16*)cb);
389
390 /*
391 * Calculate starting position of the byte sequence in
392 * the destination using the fact that p = (pt >> (12 - lg)) + 1
393 * and make sure we don't go too far back.
394 */
395 dp_back_addr = dp_addr - (pt >> (12 - lg)) - 1;
396 if (dp_back_addr < dp_sb_start)
397 goto return_overflow;
398
399 /* Now calculate the length of the byte sequence. */
400 length = (pt & (0xfff >> lg)) + 3;
401
402 /* Advance destination position and verify it is in range. */
403 *dest_ofs += length;
404 if (*dest_ofs > do_sb_end)
405 goto return_overflow;
406
407 /* The number of non-overlapping bytes. */
408 max_non_overlap = dp_addr - dp_back_addr;
409
410 if (length <= max_non_overlap) {
411 /* The byte sequence doesn't overlap, just copy it. */
412 memcpy(dp_addr, dp_back_addr, length);
413
414 /* Advance destination pointer. */
415 dp_addr += length;
416 } else {
417 /*
418 * The byte sequence does overlap, copy non-overlapping
419 * part and then do a slow byte by byte copy for the
420 * overlapping part. Also, advance the destination
421 * pointer.
422 */
423 memcpy(dp_addr, dp_back_addr, max_non_overlap);
424 dp_addr += max_non_overlap;
425 dp_back_addr += max_non_overlap;
426 length -= max_non_overlap;
427 while (length--)
428 *dp_addr++ = *dp_back_addr++;
429 }
430
431 /* Advance source position and continue with the next token. */
432 cb += 2;
433 }
434
435 /* No tokens left in the current tag. Continue with the next tag. */
436 goto do_next_tag;
437
438return_overflow:
439 ntfs_error(NULL, "Failed. Returning -EOVERFLOW.");
440 goto return_error;
441}
442
443/**
444 * ntfs_read_compressed_block - read a compressed block into the page cache
445 * @page: locked page in the compression block(s) we need to read
446 *
447 * When we are called the page has already been verified to be locked and the
448 * attribute is known to be non-resident, not encrypted, but compressed.
449 *
450 * 1. Determine which compression block(s) @page is in.
451 * 2. Get hold of all pages corresponding to this/these compression block(s).
452 * 3. Read the (first) compression block.
453 * 4. Decompress it into the corresponding pages.
454 * 5. Throw the compressed data away and proceed to 3. for the next compression
455 * block or return success if no more compression blocks left.
456 *
457 * Warning: We have to be careful what we do about existing pages. They might
458 * have been written to so that we would lose data if we were to just overwrite
459 * them with the out-of-date uncompressed data.
460 *
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300461 * FIXME: For PAGE_SIZE > cb_size we are not doing the Right Thing(TM) at
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 * the end of the file I think. We need to detect this case and zero the out
463 * of bounds remainder of the page in question and mark it as handled. At the
464 * moment we would just return -EIO on such a page. This bug will only become
465 * apparent if pages are above 8kiB and the NTFS volume only uses 512 byte
466 * clusters so is probably not going to be seen by anyone. Still this should
467 * be fixed. (AIA)
468 *
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300469 * FIXME: Again for PAGE_SIZE > cb_size we are screwing up both in
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 * handling sparse and compressed cbs. (AIA)
471 *
472 * FIXME: At the moment we don't do any zeroing out in the case that
473 * initialized_size is less than data_size. This should be safe because of the
474 * nature of the compression algorithm used. Just in case we check and output
475 * an error message in read inode if the two sizes are not equal for a
476 * compressed file. (AIA)
477 */
478int ntfs_read_compressed_block(struct page *page)
479{
Anton Altaparmakov36763672004-11-18 13:46:45 +0000480 loff_t i_size;
481 s64 initialized_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 struct address_space *mapping = page->mapping;
483 ntfs_inode *ni = NTFS_I(mapping->host);
484 ntfs_volume *vol = ni->vol;
485 struct super_block *sb = vol->sb;
486 runlist_element *rl;
Anton Altaparmakov36763672004-11-18 13:46:45 +0000487 unsigned long flags, block_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 unsigned char block_size_bits = sb->s_blocksize_bits;
489 u8 *cb, *cb_pos, *cb_end;
490 struct buffer_head **bhs;
491 unsigned long offset, index = page->index;
492 u32 cb_size = ni->itype.compressed.block_size;
493 u64 cb_size_mask = cb_size - 1UL;
494 VCN vcn;
495 LCN lcn;
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300496 /* The first wanted vcn (minimum alignment is PAGE_SIZE). */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300497 VCN start_vcn = (((s64)index << PAGE_SHIFT) & ~cb_size_mask) >>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 vol->cluster_size_bits;
499 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300500 * The first vcn after the last wanted vcn (minimum alignment is again
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300501 * PAGE_SIZE.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300503 VCN end_vcn = ((((s64)(index + 1UL) << PAGE_SHIFT) + cb_size - 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 & ~cb_size_mask) >> vol->cluster_size_bits;
505 /* Number of compression blocks (cbs) in the wanted vcn range. */
506 unsigned int nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits
507 >> ni->itype.compressed.block_size_bits;
508 /*
509 * Number of pages required to store the uncompressed data from all
510 * compression blocks (cbs) overlapping @page. Due to alignment
511 * guarantees of start_vcn and end_vcn, no need to round up here.
512 */
513 unsigned int nr_pages = (end_vcn - start_vcn) <<
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300514 vol->cluster_size_bits >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 unsigned int xpage, max_page, cur_page, cur_ofs, i;
516 unsigned int cb_clusters, cb_max_ofs;
517 int block, max_block, cb_max_page, bhs_size, nr_bhs, err = 0;
518 struct page **pages;
519 unsigned char xpage_done = 0;
520
521 ntfs_debug("Entering, page->index = 0x%lx, cb_size = 0x%x, nr_pages = "
522 "%i.", index, cb_size, nr_pages);
523 /*
524 * Bad things happen if we get here for anything that is not an
525 * unnamed $DATA attribute.
526 */
527 BUG_ON(ni->type != AT_DATA);
528 BUG_ON(ni->name_len);
529
530 pages = kmalloc(nr_pages * sizeof(struct page *), GFP_NOFS);
531
532 /* Allocate memory to store the buffer heads we need. */
533 bhs_size = cb_size / block_size * sizeof(struct buffer_head *);
534 bhs = kmalloc(bhs_size, GFP_NOFS);
535
536 if (unlikely(!pages || !bhs)) {
537 kfree(bhs);
538 kfree(pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 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 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300548 offset = start_vcn << vol->cluster_size_bits >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 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 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000555 read_lock_irqsave(&ni->size_lock, flags);
556 i_size = i_size_read(VFS_I(ni));
557 initialized_size = ni->initialized_size;
558 read_unlock_irqrestore(&ni->size_lock, flags);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300559 max_page = ((i_size + PAGE_SIZE - 1) >> PAGE_SHIFT) -
Anton Altaparmakov36763672004-11-18 13:46:45 +0000560 offset;
Anton Altaparmakovebab8992007-11-03 07:38:59 +0000561 /* Is the page fully outside i_size? (truncate in progress) */
562 if (xpage >= max_page) {
563 kfree(bhs);
564 kfree(pages);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300565 zero_user(page, 0, PAGE_SIZE);
Anton Altaparmakovebab8992007-11-03 07:38:59 +0000566 ntfs_debug("Compressed read outside i_size - truncated?");
567 SetPageUptodate(page);
568 unlock_page(page);
569 return 0;
570 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 if (nr_pages < max_page)
572 max_page = nr_pages;
573 for (i = 0; i < max_page; i++, offset++) {
574 if (i != xpage)
575 pages[i] = grab_cache_page_nowait(mapping, offset);
576 page = pages[i];
577 if (page) {
578 /*
579 * We only (re)read the page if it isn't already read
580 * in and/or dirty or we would be losing data or at
581 * least wasting our time.
582 */
583 if (!PageDirty(page) && (!PageUptodate(page) ||
584 PageError(page))) {
585 ClearPageError(page);
586 kmap(page);
587 continue;
588 }
589 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300590 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 pages[i] = NULL;
592 }
593 }
594
595 /*
596 * We have the runlist, and all the destination pages we need to fill.
597 * Now read the first compression block.
598 */
599 cur_page = 0;
600 cur_ofs = 0;
601 cb_clusters = ni->itype.compressed.block_clusters;
602do_next_cb:
603 nr_cbs--;
604 nr_bhs = 0;
605
606 /* Read all cb buffer heads one cluster at a time. */
607 rl = NULL;
608 for (vcn = start_vcn, start_vcn += cb_clusters; vcn < start_vcn;
609 vcn++) {
Richard Knutssonc49c3112006-09-30 23:27:12 -0700610 bool is_retry = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611
612 if (!rl) {
613lock_retry_remap:
614 down_read(&ni->runlist.lock);
615 rl = ni->runlist.rl;
616 }
617 if (likely(rl != NULL)) {
618 /* Seek to element containing target vcn. */
619 while (rl->length && rl[1].vcn <= vcn)
620 rl++;
621 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
622 } else
623 lcn = LCN_RL_NOT_MAPPED;
624 ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
625 (unsigned long long)vcn,
626 (unsigned long long)lcn);
627 if (lcn < 0) {
628 /*
629 * When we reach the first sparse cluster we have
630 * finished with the cb.
631 */
632 if (lcn == LCN_HOLE)
633 break;
634 if (is_retry || lcn != LCN_RL_NOT_MAPPED)
635 goto rl_err;
Richard Knutssonc49c3112006-09-30 23:27:12 -0700636 is_retry = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 /*
638 * Attempt to map runlist, dropping lock for the
639 * duration.
640 */
641 up_read(&ni->runlist.lock);
642 if (!ntfs_map_runlist(ni, vcn))
643 goto lock_retry_remap;
644 goto map_rl_err;
645 }
646 block = lcn << vol->cluster_size_bits >> block_size_bits;
647 /* Read the lcn from device in chunks of block_size bytes. */
648 max_block = block + (vol->cluster_size >> block_size_bits);
649 do {
650 ntfs_debug("block = 0x%x.", block);
651 if (unlikely(!(bhs[nr_bhs] = sb_getblk(sb, block))))
652 goto getblk_err;
653 nr_bhs++;
654 } while (++block < max_block);
655 }
656
657 /* Release the lock if we took it. */
658 if (rl)
659 up_read(&ni->runlist.lock);
660
661 /* Setup and initiate io on all buffer heads. */
662 for (i = 0; i < nr_bhs; i++) {
663 struct buffer_head *tbh = bhs[i];
664
Nick Pigginca5de402008-08-02 12:02:13 +0200665 if (!trylock_buffer(tbh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 continue;
667 if (unlikely(buffer_uptodate(tbh))) {
668 unlock_buffer(tbh);
669 continue;
670 }
671 get_bh(tbh);
672 tbh->b_end_io = end_buffer_read_sync;
Mike Christie2a222ca2016-06-05 14:31:43 -0500673 submit_bh(REQ_OP_READ, 0, tbh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 }
675
676 /* Wait for io completion on all buffer heads. */
677 for (i = 0; i < nr_bhs; i++) {
678 struct buffer_head *tbh = bhs[i];
679
680 if (buffer_uptodate(tbh))
681 continue;
682 wait_on_buffer(tbh);
683 /*
684 * We need an optimization barrier here, otherwise we start
685 * hitting the below fixup code when accessing a loopback
686 * mounted ntfs partition. This indicates either there is a
687 * race condition in the loop driver or, more likely, gcc
688 * overoptimises the code without the barrier and it doesn't
689 * do the Right Thing(TM).
690 */
691 barrier();
692 if (unlikely(!buffer_uptodate(tbh))) {
693 ntfs_warning(vol->sb, "Buffer is unlocked but not "
694 "uptodate! Unplugging the disk queue "
695 "and rescheduling.");
696 get_bh(tbh);
Jens Axboe7eaceac2011-03-10 08:52:07 +0100697 io_schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 put_bh(tbh);
699 if (unlikely(!buffer_uptodate(tbh)))
700 goto read_err;
701 ntfs_warning(vol->sb, "Buffer is now uptodate. Good.");
702 }
703 }
704
705 /*
706 * Get the compression buffer. We must not sleep any more
707 * until we are finished with it.
708 */
709 spin_lock(&ntfs_cb_lock);
710 cb = ntfs_compression_buffer;
711
712 BUG_ON(!cb);
713
714 cb_pos = cb;
715 cb_end = cb + cb_size;
716
717 /* Copy the buffer heads into the contiguous buffer. */
718 for (i = 0; i < nr_bhs; i++) {
719 memcpy(cb_pos, bhs[i]->b_data, block_size);
720 cb_pos += block_size;
721 }
722
723 /* Just a precaution. */
724 if (cb_pos + 2 <= cb + cb_size)
725 *(u16*)cb_pos = 0;
726
727 /* Reset cb_pos back to the beginning. */
728 cb_pos = cb;
729
730 /* We now have both source (if present) and destination. */
731 ntfs_debug("Successfully read the compression block.");
732
733 /* The last page and maximum offset within it for the current cb. */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300734 cb_max_page = (cur_page << PAGE_SHIFT) + cur_ofs + cb_size;
735 cb_max_ofs = cb_max_page & ~PAGE_MASK;
736 cb_max_page >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737
738 /* Catch end of file inside a compression block. */
739 if (cb_max_page > max_page)
740 cb_max_page = max_page;
741
742 if (vcn == start_vcn - cb_clusters) {
743 /* Sparse cb, zero out page range overlapping the cb. */
744 ntfs_debug("Found sparse compression block.");
745 /* We can sleep from now on, so we drop lock. */
746 spin_unlock(&ntfs_cb_lock);
747 if (cb_max_ofs)
748 cb_max_page--;
749 for (; cur_page < cb_max_page; cur_page++) {
750 page = pages[cur_page];
751 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 if (likely(!cur_ofs))
753 clear_page(page_address(page));
754 else
755 memset(page_address(page) + cur_ofs, 0,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300756 PAGE_SIZE -
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 cur_ofs);
758 flush_dcache_page(page);
759 kunmap(page);
760 SetPageUptodate(page);
761 unlock_page(page);
762 if (cur_page == xpage)
763 xpage_done = 1;
764 else
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300765 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 pages[cur_page] = NULL;
767 }
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300768 cb_pos += PAGE_SIZE - cur_ofs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 cur_ofs = 0;
770 if (cb_pos >= cb_end)
771 break;
772 }
773 /* If we have a partial final page, deal with it now. */
774 if (cb_max_ofs && cb_pos < cb_end) {
775 page = pages[cur_page];
776 if (page)
777 memset(page_address(page) + cur_ofs, 0,
778 cb_max_ofs - cur_ofs);
779 /*
780 * No need to update cb_pos at this stage:
781 * cb_pos += cb_max_ofs - cur_ofs;
782 */
783 cur_ofs = cb_max_ofs;
784 }
785 } else if (vcn == start_vcn) {
786 /* We can't sleep so we need two stages. */
787 unsigned int cur2_page = cur_page;
788 unsigned int cur_ofs2 = cur_ofs;
789 u8 *cb_pos2 = cb_pos;
790
791 ntfs_debug("Found uncompressed compression block.");
792 /* Uncompressed cb, copy it to the destination pages. */
793 /*
794 * TODO: As a big optimization, we could detect this case
795 * before we read all the pages and use block_read_full_page()
796 * on all full pages instead (we still have to treat partial
797 * pages especially but at least we are getting rid of the
798 * synchronous io for the majority of pages.
799 * Or if we choose not to do the read-ahead/-behind stuff, we
800 * could just return block_read_full_page(pages[xpage]) as long
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +0300801 * as PAGE_SIZE <= cb_size.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 */
803 if (cb_max_ofs)
804 cb_max_page--;
805 /* First stage: copy data into destination pages. */
806 for (; cur_page < cb_max_page; cur_page++) {
807 page = pages[cur_page];
808 if (page)
809 memcpy(page_address(page) + cur_ofs, cb_pos,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300810 PAGE_SIZE - cur_ofs);
811 cb_pos += PAGE_SIZE - cur_ofs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 cur_ofs = 0;
813 if (cb_pos >= cb_end)
814 break;
815 }
816 /* If we have a partial final page, deal with it now. */
817 if (cb_max_ofs && cb_pos < cb_end) {
818 page = pages[cur_page];
819 if (page)
820 memcpy(page_address(page) + cur_ofs, cb_pos,
821 cb_max_ofs - cur_ofs);
822 cb_pos += cb_max_ofs - cur_ofs;
823 cur_ofs = cb_max_ofs;
824 }
825 /* We can sleep from now on, so drop lock. */
826 spin_unlock(&ntfs_cb_lock);
827 /* Second stage: finalize pages. */
828 for (; cur2_page < cb_max_page; cur2_page++) {
829 page = pages[cur2_page];
830 if (page) {
831 /*
832 * If we are outside the initialized size, zero
833 * the out of bounds page range.
834 */
Anton Altaparmakov36763672004-11-18 13:46:45 +0000835 handle_bounds_compressed_page(page, i_size,
836 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 flush_dcache_page(page);
838 kunmap(page);
839 SetPageUptodate(page);
840 unlock_page(page);
841 if (cur2_page == xpage)
842 xpage_done = 1;
843 else
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300844 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 pages[cur2_page] = NULL;
846 }
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300847 cb_pos2 += PAGE_SIZE - cur_ofs2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 cur_ofs2 = 0;
849 if (cb_pos2 >= cb_end)
850 break;
851 }
852 } else {
853 /* Compressed cb, decompress it into the destination page(s). */
854 unsigned int prev_cur_page = cur_page;
855
856 ntfs_debug("Found compressed compression block.");
857 err = ntfs_decompress(pages, &cur_page, &cur_ofs,
858 cb_max_page, cb_max_ofs, xpage, &xpage_done,
Anton Altaparmakov36763672004-11-18 13:46:45 +0000859 cb_pos, cb_size - (cb_pos - cb), i_size,
860 initialized_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 /*
862 * We can sleep from now on, lock already dropped by
863 * ntfs_decompress().
864 */
865 if (err) {
866 ntfs_error(vol->sb, "ntfs_decompress() failed in inode "
867 "0x%lx with error code %i. Skipping "
868 "this compression block.",
869 ni->mft_no, -err);
870 /* Release the unfinished pages. */
871 for (; prev_cur_page < cur_page; prev_cur_page++) {
872 page = pages[prev_cur_page];
873 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 flush_dcache_page(page);
875 kunmap(page);
876 unlock_page(page);
877 if (prev_cur_page != xpage)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300878 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 pages[prev_cur_page] = NULL;
880 }
881 }
882 }
883 }
884
885 /* Release the buffer heads. */
886 for (i = 0; i < nr_bhs; i++)
887 brelse(bhs[i]);
888
889 /* Do we have more work to do? */
890 if (nr_cbs)
891 goto do_next_cb;
892
893 /* We no longer need the list of buffer heads. */
894 kfree(bhs);
895
896 /* Clean up if we have any pages left. Should never happen. */
897 for (cur_page = 0; cur_page < max_page; cur_page++) {
898 page = pages[cur_page];
899 if (page) {
900 ntfs_error(vol->sb, "Still have pages left! "
901 "Terminating them with extreme "
902 "prejudice. Inode 0x%lx, page index "
903 "0x%lx.", ni->mft_no, page->index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 flush_dcache_page(page);
905 kunmap(page);
906 unlock_page(page);
907 if (cur_page != xpage)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300908 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 pages[cur_page] = NULL;
910 }
911 }
912
913 /* We no longer need the list of pages. */
914 kfree(pages);
915
916 /* If we have completed the requested page, we return success. */
917 if (likely(xpage_done))
918 return 0;
919
920 ntfs_debug("Failed. Returning error code %s.", err == -EOVERFLOW ?
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200921 "EOVERFLOW" : (!err ? "EIO" : "unknown error"));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 return err < 0 ? err : -EIO;
923
924read_err:
925 ntfs_error(vol->sb, "IO error while reading compressed data.");
926 /* Release the buffer heads. */
927 for (i = 0; i < nr_bhs; i++)
928 brelse(bhs[i]);
929 goto err_out;
930
931map_rl_err:
932 ntfs_error(vol->sb, "ntfs_map_runlist() failed. Cannot read "
933 "compression block.");
934 goto err_out;
935
936rl_err:
937 up_read(&ni->runlist.lock);
938 ntfs_error(vol->sb, "ntfs_rl_vcn_to_lcn() failed. Cannot read "
939 "compression block.");
940 goto err_out;
941
942getblk_err:
943 up_read(&ni->runlist.lock);
944 ntfs_error(vol->sb, "getblk() failed. Cannot read compression block.");
945
946err_out:
947 kfree(bhs);
948 for (i = cur_page; i < max_page; i++) {
949 page = pages[i];
950 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 flush_dcache_page(page);
952 kunmap(page);
953 unlock_page(page);
954 if (i != xpage)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300955 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 }
957 }
958 kfree(pages);
959 return -EIO;
960}