Loading...
1/**
2 * aops.c - NTFS kernel address space operations and page cache handling.
3 * Part of the Linux-NTFS project.
4 *
5 * Copyright (c) 2001-2007 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/errno.h>
25#include <linux/fs.h>
26#include <linux/gfp.h>
27#include <linux/mm.h>
28#include <linux/pagemap.h>
29#include <linux/swap.h>
30#include <linux/buffer_head.h>
31#include <linux/writeback.h>
32#include <linux/bit_spinlock.h>
33
34#include "aops.h"
35#include "attrib.h"
36#include "debug.h"
37#include "inode.h"
38#include "mft.h"
39#include "runlist.h"
40#include "types.h"
41#include "ntfs.h"
42
43/**
44 * ntfs_end_buffer_async_read - async io completion for reading attributes
45 * @bh: buffer head on which io is completed
46 * @uptodate: whether @bh is now uptodate or not
47 *
48 * Asynchronous I/O completion handler for reading pages belonging to the
49 * attribute address space of an inode. The inodes can either be files or
50 * directories or they can be fake inodes describing some attribute.
51 *
52 * If NInoMstProtected(), perform the post read mst fixups when all IO on the
53 * page has been completed and mark the page uptodate or set the error bit on
54 * the page. To determine the size of the records that need fixing up, we
55 * cheat a little bit by setting the index_block_size in ntfs_inode to the ntfs
56 * record size, and index_block_size_bits, to the log(base 2) of the ntfs
57 * record size.
58 */
59static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
60{
61 unsigned long flags;
62 struct buffer_head *first, *tmp;
63 struct page *page;
64 struct inode *vi;
65 ntfs_inode *ni;
66 int page_uptodate = 1;
67
68 page = bh->b_page;
69 vi = page->mapping->host;
70 ni = NTFS_I(vi);
71
72 if (likely(uptodate)) {
73 loff_t i_size;
74 s64 file_ofs, init_size;
75
76 set_buffer_uptodate(bh);
77
78 file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
79 bh_offset(bh);
80 read_lock_irqsave(&ni->size_lock, flags);
81 init_size = ni->initialized_size;
82 i_size = i_size_read(vi);
83 read_unlock_irqrestore(&ni->size_lock, flags);
84 if (unlikely(init_size > i_size)) {
85 /* Race with shrinking truncate. */
86 init_size = i_size;
87 }
88 /* Check for the current buffer head overflowing. */
89 if (unlikely(file_ofs + bh->b_size > init_size)) {
90 int ofs;
91 void *kaddr;
92
93 ofs = 0;
94 if (file_ofs < init_size)
95 ofs = init_size - file_ofs;
96 local_irq_save(flags);
97 kaddr = kmap_atomic(page);
98 memset(kaddr + bh_offset(bh) + ofs, 0,
99 bh->b_size - ofs);
100 flush_dcache_page(page);
101 kunmap_atomic(kaddr);
102 local_irq_restore(flags);
103 }
104 } else {
105 clear_buffer_uptodate(bh);
106 SetPageError(page);
107 ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
108 "0x%llx.", (unsigned long long)bh->b_blocknr);
109 }
110 first = page_buffers(page);
111 local_irq_save(flags);
112 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
113 clear_buffer_async_read(bh);
114 unlock_buffer(bh);
115 tmp = bh;
116 do {
117 if (!buffer_uptodate(tmp))
118 page_uptodate = 0;
119 if (buffer_async_read(tmp)) {
120 if (likely(buffer_locked(tmp)))
121 goto still_busy;
122 /* Async buffers must be locked. */
123 BUG();
124 }
125 tmp = tmp->b_this_page;
126 } while (tmp != bh);
127 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
128 local_irq_restore(flags);
129 /*
130 * If none of the buffers had errors then we can set the page uptodate,
131 * but we first have to perform the post read mst fixups, if the
132 * attribute is mst protected, i.e. if NInoMstProteced(ni) is true.
133 * Note we ignore fixup errors as those are detected when
134 * map_mft_record() is called which gives us per record granularity
135 * rather than per page granularity.
136 */
137 if (!NInoMstProtected(ni)) {
138 if (likely(page_uptodate && !PageError(page)))
139 SetPageUptodate(page);
140 } else {
141 u8 *kaddr;
142 unsigned int i, recs;
143 u32 rec_size;
144
145 rec_size = ni->itype.index.block_size;
146 recs = PAGE_CACHE_SIZE / rec_size;
147 /* Should have been verified before we got here... */
148 BUG_ON(!recs);
149 local_irq_save(flags);
150 kaddr = kmap_atomic(page);
151 for (i = 0; i < recs; i++)
152 post_read_mst_fixup((NTFS_RECORD*)(kaddr +
153 i * rec_size), rec_size);
154 kunmap_atomic(kaddr);
155 local_irq_restore(flags);
156 flush_dcache_page(page);
157 if (likely(page_uptodate && !PageError(page)))
158 SetPageUptodate(page);
159 }
160 unlock_page(page);
161 return;
162still_busy:
163 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
164 local_irq_restore(flags);
165 return;
166}
167
168/**
169 * ntfs_read_block - fill a @page of an address space with data
170 * @page: page cache page to fill with data
171 *
172 * Fill the page @page of the address space belonging to the @page->host inode.
173 * We read each buffer asynchronously and when all buffers are read in, our io
174 * completion handler ntfs_end_buffer_read_async(), if required, automatically
175 * applies the mst fixups to the page before finally marking it uptodate and
176 * unlocking it.
177 *
178 * We only enforce allocated_size limit because i_size is checked for in
179 * generic_file_read().
180 *
181 * Return 0 on success and -errno on error.
182 *
183 * Contains an adapted version of fs/buffer.c::block_read_full_page().
184 */
185static int ntfs_read_block(struct page *page)
186{
187 loff_t i_size;
188 VCN vcn;
189 LCN lcn;
190 s64 init_size;
191 struct inode *vi;
192 ntfs_inode *ni;
193 ntfs_volume *vol;
194 runlist_element *rl;
195 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
196 sector_t iblock, lblock, zblock;
197 unsigned long flags;
198 unsigned int blocksize, vcn_ofs;
199 int i, nr;
200 unsigned char blocksize_bits;
201
202 vi = page->mapping->host;
203 ni = NTFS_I(vi);
204 vol = ni->vol;
205
206 /* $MFT/$DATA must have its complete runlist in memory at all times. */
207 BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
208
209 blocksize = vol->sb->s_blocksize;
210 blocksize_bits = vol->sb->s_blocksize_bits;
211
212 if (!page_has_buffers(page)) {
213 create_empty_buffers(page, blocksize, 0);
214 if (unlikely(!page_has_buffers(page))) {
215 unlock_page(page);
216 return -ENOMEM;
217 }
218 }
219 bh = head = page_buffers(page);
220 BUG_ON(!bh);
221
222 /*
223 * We may be racing with truncate. To avoid some of the problems we
224 * now take a snapshot of the various sizes and use those for the whole
225 * of the function. In case of an extending truncate it just means we
226 * may leave some buffers unmapped which are now allocated. This is
227 * not a problem since these buffers will just get mapped when a write
228 * occurs. In case of a shrinking truncate, we will detect this later
229 * on due to the runlist being incomplete and if the page is being
230 * fully truncated, truncate will throw it away as soon as we unlock
231 * it so no need to worry what we do with it.
232 */
233 iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
234 read_lock_irqsave(&ni->size_lock, flags);
235 lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
236 init_size = ni->initialized_size;
237 i_size = i_size_read(vi);
238 read_unlock_irqrestore(&ni->size_lock, flags);
239 if (unlikely(init_size > i_size)) {
240 /* Race with shrinking truncate. */
241 init_size = i_size;
242 }
243 zblock = (init_size + blocksize - 1) >> blocksize_bits;
244
245 /* Loop through all the buffers in the page. */
246 rl = NULL;
247 nr = i = 0;
248 do {
249 int err = 0;
250
251 if (unlikely(buffer_uptodate(bh)))
252 continue;
253 if (unlikely(buffer_mapped(bh))) {
254 arr[nr++] = bh;
255 continue;
256 }
257 bh->b_bdev = vol->sb->s_bdev;
258 /* Is the block within the allowed limits? */
259 if (iblock < lblock) {
260 bool is_retry = false;
261
262 /* Convert iblock into corresponding vcn and offset. */
263 vcn = (VCN)iblock << blocksize_bits >>
264 vol->cluster_size_bits;
265 vcn_ofs = ((VCN)iblock << blocksize_bits) &
266 vol->cluster_size_mask;
267 if (!rl) {
268lock_retry_remap:
269 down_read(&ni->runlist.lock);
270 rl = ni->runlist.rl;
271 }
272 if (likely(rl != NULL)) {
273 /* Seek to element containing target vcn. */
274 while (rl->length && rl[1].vcn <= vcn)
275 rl++;
276 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
277 } else
278 lcn = LCN_RL_NOT_MAPPED;
279 /* Successful remap. */
280 if (lcn >= 0) {
281 /* Setup buffer head to correct block. */
282 bh->b_blocknr = ((lcn << vol->cluster_size_bits)
283 + vcn_ofs) >> blocksize_bits;
284 set_buffer_mapped(bh);
285 /* Only read initialized data blocks. */
286 if (iblock < zblock) {
287 arr[nr++] = bh;
288 continue;
289 }
290 /* Fully non-initialized data block, zero it. */
291 goto handle_zblock;
292 }
293 /* It is a hole, need to zero it. */
294 if (lcn == LCN_HOLE)
295 goto handle_hole;
296 /* If first try and runlist unmapped, map and retry. */
297 if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
298 is_retry = true;
299 /*
300 * Attempt to map runlist, dropping lock for
301 * the duration.
302 */
303 up_read(&ni->runlist.lock);
304 err = ntfs_map_runlist(ni, vcn);
305 if (likely(!err))
306 goto lock_retry_remap;
307 rl = NULL;
308 } else if (!rl)
309 up_read(&ni->runlist.lock);
310 /*
311 * If buffer is outside the runlist, treat it as a
312 * hole. This can happen due to concurrent truncate
313 * for example.
314 */
315 if (err == -ENOENT || lcn == LCN_ENOENT) {
316 err = 0;
317 goto handle_hole;
318 }
319 /* Hard error, zero out region. */
320 if (!err)
321 err = -EIO;
322 bh->b_blocknr = -1;
323 SetPageError(page);
324 ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
325 "attribute type 0x%x, vcn 0x%llx, "
326 "offset 0x%x because its location on "
327 "disk could not be determined%s "
328 "(error code %i).", ni->mft_no,
329 ni->type, (unsigned long long)vcn,
330 vcn_ofs, is_retry ? " even after "
331 "retrying" : "", err);
332 }
333 /*
334 * Either iblock was outside lblock limits or
335 * ntfs_rl_vcn_to_lcn() returned error. Just zero that portion
336 * of the page and set the buffer uptodate.
337 */
338handle_hole:
339 bh->b_blocknr = -1UL;
340 clear_buffer_mapped(bh);
341handle_zblock:
342 zero_user(page, i * blocksize, blocksize);
343 if (likely(!err))
344 set_buffer_uptodate(bh);
345 } while (i++, iblock++, (bh = bh->b_this_page) != head);
346
347 /* Release the lock if we took it. */
348 if (rl)
349 up_read(&ni->runlist.lock);
350
351 /* Check we have at least one buffer ready for i/o. */
352 if (nr) {
353 struct buffer_head *tbh;
354
355 /* Lock the buffers. */
356 for (i = 0; i < nr; i++) {
357 tbh = arr[i];
358 lock_buffer(tbh);
359 tbh->b_end_io = ntfs_end_buffer_async_read;
360 set_buffer_async_read(tbh);
361 }
362 /* Finally, start i/o on the buffers. */
363 for (i = 0; i < nr; i++) {
364 tbh = arr[i];
365 if (likely(!buffer_uptodate(tbh)))
366 submit_bh(READ, tbh);
367 else
368 ntfs_end_buffer_async_read(tbh, 1);
369 }
370 return 0;
371 }
372 /* No i/o was scheduled on any of the buffers. */
373 if (likely(!PageError(page)))
374 SetPageUptodate(page);
375 else /* Signal synchronous i/o error. */
376 nr = -EIO;
377 unlock_page(page);
378 return nr;
379}
380
381/**
382 * ntfs_readpage - fill a @page of a @file with data from the device
383 * @file: open file to which the page @page belongs or NULL
384 * @page: page cache page to fill with data
385 *
386 * For non-resident attributes, ntfs_readpage() fills the @page of the open
387 * file @file by calling the ntfs version of the generic block_read_full_page()
388 * function, ntfs_read_block(), which in turn creates and reads in the buffers
389 * associated with the page asynchronously.
390 *
391 * For resident attributes, OTOH, ntfs_readpage() fills @page by copying the
392 * data from the mft record (which at this stage is most likely in memory) and
393 * fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as
394 * even if the mft record is not cached at this point in time, we need to wait
395 * for it to be read in before we can do the copy.
396 *
397 * Return 0 on success and -errno on error.
398 */
399static int ntfs_readpage(struct file *file, struct page *page)
400{
401 loff_t i_size;
402 struct inode *vi;
403 ntfs_inode *ni, *base_ni;
404 u8 *addr;
405 ntfs_attr_search_ctx *ctx;
406 MFT_RECORD *mrec;
407 unsigned long flags;
408 u32 attr_len;
409 int err = 0;
410
411retry_readpage:
412 BUG_ON(!PageLocked(page));
413 vi = page->mapping->host;
414 i_size = i_size_read(vi);
415 /* Is the page fully outside i_size? (truncate in progress) */
416 if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
417 PAGE_CACHE_SHIFT)) {
418 zero_user(page, 0, PAGE_CACHE_SIZE);
419 ntfs_debug("Read outside i_size - truncated?");
420 goto done;
421 }
422 /*
423 * This can potentially happen because we clear PageUptodate() during
424 * ntfs_writepage() of MstProtected() attributes.
425 */
426 if (PageUptodate(page)) {
427 unlock_page(page);
428 return 0;
429 }
430 ni = NTFS_I(vi);
431 /*
432 * Only $DATA attributes can be encrypted and only unnamed $DATA
433 * attributes can be compressed. Index root can have the flags set but
434 * this means to create compressed/encrypted files, not that the
435 * attribute is compressed/encrypted. Note we need to check for
436 * AT_INDEX_ALLOCATION since this is the type of both directory and
437 * index inodes.
438 */
439 if (ni->type != AT_INDEX_ALLOCATION) {
440 /* If attribute is encrypted, deny access, just like NT4. */
441 if (NInoEncrypted(ni)) {
442 BUG_ON(ni->type != AT_DATA);
443 err = -EACCES;
444 goto err_out;
445 }
446 /* Compressed data streams are handled in compress.c. */
447 if (NInoNonResident(ni) && NInoCompressed(ni)) {
448 BUG_ON(ni->type != AT_DATA);
449 BUG_ON(ni->name_len);
450 return ntfs_read_compressed_block(page);
451 }
452 }
453 /* NInoNonResident() == NInoIndexAllocPresent() */
454 if (NInoNonResident(ni)) {
455 /* Normal, non-resident data stream. */
456 return ntfs_read_block(page);
457 }
458 /*
459 * Attribute is resident, implying it is not compressed or encrypted.
460 * This also means the attribute is smaller than an mft record and
461 * hence smaller than a page, so can simply zero out any pages with
462 * index above 0. Note the attribute can actually be marked compressed
463 * but if it is resident the actual data is not compressed so we are
464 * ok to ignore the compressed flag here.
465 */
466 if (unlikely(page->index > 0)) {
467 zero_user(page, 0, PAGE_CACHE_SIZE);
468 goto done;
469 }
470 if (!NInoAttr(ni))
471 base_ni = ni;
472 else
473 base_ni = ni->ext.base_ntfs_ino;
474 /* Map, pin, and lock the mft record. */
475 mrec = map_mft_record(base_ni);
476 if (IS_ERR(mrec)) {
477 err = PTR_ERR(mrec);
478 goto err_out;
479 }
480 /*
481 * If a parallel write made the attribute non-resident, drop the mft
482 * record and retry the readpage.
483 */
484 if (unlikely(NInoNonResident(ni))) {
485 unmap_mft_record(base_ni);
486 goto retry_readpage;
487 }
488 ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
489 if (unlikely(!ctx)) {
490 err = -ENOMEM;
491 goto unm_err_out;
492 }
493 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
494 CASE_SENSITIVE, 0, NULL, 0, ctx);
495 if (unlikely(err))
496 goto put_unm_err_out;
497 attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
498 read_lock_irqsave(&ni->size_lock, flags);
499 if (unlikely(attr_len > ni->initialized_size))
500 attr_len = ni->initialized_size;
501 i_size = i_size_read(vi);
502 read_unlock_irqrestore(&ni->size_lock, flags);
503 if (unlikely(attr_len > i_size)) {
504 /* Race with shrinking truncate. */
505 attr_len = i_size;
506 }
507 addr = kmap_atomic(page);
508 /* Copy the data to the page. */
509 memcpy(addr, (u8*)ctx->attr +
510 le16_to_cpu(ctx->attr->data.resident.value_offset),
511 attr_len);
512 /* Zero the remainder of the page. */
513 memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
514 flush_dcache_page(page);
515 kunmap_atomic(addr);
516put_unm_err_out:
517 ntfs_attr_put_search_ctx(ctx);
518unm_err_out:
519 unmap_mft_record(base_ni);
520done:
521 SetPageUptodate(page);
522err_out:
523 unlock_page(page);
524 return err;
525}
526
527#ifdef NTFS_RW
528
529/**
530 * ntfs_write_block - write a @page to the backing store
531 * @page: page cache page to write out
532 * @wbc: writeback control structure
533 *
534 * This function is for writing pages belonging to non-resident, non-mst
535 * protected attributes to their backing store.
536 *
537 * For a page with buffers, map and write the dirty buffers asynchronously
538 * under page writeback. For a page without buffers, create buffers for the
539 * page, then proceed as above.
540 *
541 * If a page doesn't have buffers the page dirty state is definitive. If a page
542 * does have buffers, the page dirty state is just a hint, and the buffer dirty
543 * state is definitive. (A hint which has rules: dirty buffers against a clean
544 * page is illegal. Other combinations are legal and need to be handled. In
545 * particular a dirty page containing clean buffers for example.)
546 *
547 * Return 0 on success and -errno on error.
548 *
549 * Based on ntfs_read_block() and __block_write_full_page().
550 */
551static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
552{
553 VCN vcn;
554 LCN lcn;
555 s64 initialized_size;
556 loff_t i_size;
557 sector_t block, dblock, iblock;
558 struct inode *vi;
559 ntfs_inode *ni;
560 ntfs_volume *vol;
561 runlist_element *rl;
562 struct buffer_head *bh, *head;
563 unsigned long flags;
564 unsigned int blocksize, vcn_ofs;
565 int err;
566 bool need_end_writeback;
567 unsigned char blocksize_bits;
568
569 vi = page->mapping->host;
570 ni = NTFS_I(vi);
571 vol = ni->vol;
572
573 ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
574 "0x%lx.", ni->mft_no, ni->type, page->index);
575
576 BUG_ON(!NInoNonResident(ni));
577 BUG_ON(NInoMstProtected(ni));
578 blocksize = vol->sb->s_blocksize;
579 blocksize_bits = vol->sb->s_blocksize_bits;
580 if (!page_has_buffers(page)) {
581 BUG_ON(!PageUptodate(page));
582 create_empty_buffers(page, blocksize,
583 (1 << BH_Uptodate) | (1 << BH_Dirty));
584 if (unlikely(!page_has_buffers(page))) {
585 ntfs_warning(vol->sb, "Error allocating page "
586 "buffers. Redirtying page so we try "
587 "again later.");
588 /*
589 * Put the page back on mapping->dirty_pages, but leave
590 * its buffers' dirty state as-is.
591 */
592 redirty_page_for_writepage(wbc, page);
593 unlock_page(page);
594 return 0;
595 }
596 }
597 bh = head = page_buffers(page);
598 BUG_ON(!bh);
599
600 /* NOTE: Different naming scheme to ntfs_read_block()! */
601
602 /* The first block in the page. */
603 block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
604
605 read_lock_irqsave(&ni->size_lock, flags);
606 i_size = i_size_read(vi);
607 initialized_size = ni->initialized_size;
608 read_unlock_irqrestore(&ni->size_lock, flags);
609
610 /* The first out of bounds block for the data size. */
611 dblock = (i_size + blocksize - 1) >> blocksize_bits;
612
613 /* The last (fully or partially) initialized block. */
614 iblock = initialized_size >> blocksize_bits;
615
616 /*
617 * Be very careful. We have no exclusion from __set_page_dirty_buffers
618 * here, and the (potentially unmapped) buffers may become dirty at
619 * any time. If a buffer becomes dirty here after we've inspected it
620 * then we just miss that fact, and the page stays dirty.
621 *
622 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
623 * handle that here by just cleaning them.
624 */
625
626 /*
627 * Loop through all the buffers in the page, mapping all the dirty
628 * buffers to disk addresses and handling any aliases from the
629 * underlying block device's mapping.
630 */
631 rl = NULL;
632 err = 0;
633 do {
634 bool is_retry = false;
635
636 if (unlikely(block >= dblock)) {
637 /*
638 * Mapped buffers outside i_size will occur, because
639 * this page can be outside i_size when there is a
640 * truncate in progress. The contents of such buffers
641 * were zeroed by ntfs_writepage().
642 *
643 * FIXME: What about the small race window where
644 * ntfs_writepage() has not done any clearing because
645 * the page was within i_size but before we get here,
646 * vmtruncate() modifies i_size?
647 */
648 clear_buffer_dirty(bh);
649 set_buffer_uptodate(bh);
650 continue;
651 }
652
653 /* Clean buffers are not written out, so no need to map them. */
654 if (!buffer_dirty(bh))
655 continue;
656
657 /* Make sure we have enough initialized size. */
658 if (unlikely((block >= iblock) &&
659 (initialized_size < i_size))) {
660 /*
661 * If this page is fully outside initialized size, zero
662 * out all pages between the current initialized size
663 * and the current page. Just use ntfs_readpage() to do
664 * the zeroing transparently.
665 */
666 if (block > iblock) {
667 // TODO:
668 // For each page do:
669 // - read_cache_page()
670 // Again for each page do:
671 // - wait_on_page_locked()
672 // - Check (PageUptodate(page) &&
673 // !PageError(page))
674 // Update initialized size in the attribute and
675 // in the inode.
676 // Again, for each page do:
677 // __set_page_dirty_buffers();
678 // page_cache_release()
679 // We don't need to wait on the writes.
680 // Update iblock.
681 }
682 /*
683 * The current page straddles initialized size. Zero
684 * all non-uptodate buffers and set them uptodate (and
685 * dirty?). Note, there aren't any non-uptodate buffers
686 * if the page is uptodate.
687 * FIXME: For an uptodate page, the buffers may need to
688 * be written out because they were not initialized on
689 * disk before.
690 */
691 if (!PageUptodate(page)) {
692 // TODO:
693 // Zero any non-uptodate buffers up to i_size.
694 // Set them uptodate and dirty.
695 }
696 // TODO:
697 // Update initialized size in the attribute and in the
698 // inode (up to i_size).
699 // Update iblock.
700 // FIXME: This is inefficient. Try to batch the two
701 // size changes to happen in one go.
702 ntfs_error(vol->sb, "Writing beyond initialized size "
703 "is not supported yet. Sorry.");
704 err = -EOPNOTSUPP;
705 break;
706 // Do NOT set_buffer_new() BUT DO clear buffer range
707 // outside write request range.
708 // set_buffer_uptodate() on complete buffers as well as
709 // set_buffer_dirty().
710 }
711
712 /* No need to map buffers that are already mapped. */
713 if (buffer_mapped(bh))
714 continue;
715
716 /* Unmapped, dirty buffer. Need to map it. */
717 bh->b_bdev = vol->sb->s_bdev;
718
719 /* Convert block into corresponding vcn and offset. */
720 vcn = (VCN)block << blocksize_bits;
721 vcn_ofs = vcn & vol->cluster_size_mask;
722 vcn >>= vol->cluster_size_bits;
723 if (!rl) {
724lock_retry_remap:
725 down_read(&ni->runlist.lock);
726 rl = ni->runlist.rl;
727 }
728 if (likely(rl != NULL)) {
729 /* Seek to element containing target vcn. */
730 while (rl->length && rl[1].vcn <= vcn)
731 rl++;
732 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
733 } else
734 lcn = LCN_RL_NOT_MAPPED;
735 /* Successful remap. */
736 if (lcn >= 0) {
737 /* Setup buffer head to point to correct block. */
738 bh->b_blocknr = ((lcn << vol->cluster_size_bits) +
739 vcn_ofs) >> blocksize_bits;
740 set_buffer_mapped(bh);
741 continue;
742 }
743 /* It is a hole, need to instantiate it. */
744 if (lcn == LCN_HOLE) {
745 u8 *kaddr;
746 unsigned long *bpos, *bend;
747
748 /* Check if the buffer is zero. */
749 kaddr = kmap_atomic(page);
750 bpos = (unsigned long *)(kaddr + bh_offset(bh));
751 bend = (unsigned long *)((u8*)bpos + blocksize);
752 do {
753 if (unlikely(*bpos))
754 break;
755 } while (likely(++bpos < bend));
756 kunmap_atomic(kaddr);
757 if (bpos == bend) {
758 /*
759 * Buffer is zero and sparse, no need to write
760 * it.
761 */
762 bh->b_blocknr = -1;
763 clear_buffer_dirty(bh);
764 continue;
765 }
766 // TODO: Instantiate the hole.
767 // clear_buffer_new(bh);
768 // unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
769 ntfs_error(vol->sb, "Writing into sparse regions is "
770 "not supported yet. Sorry.");
771 err = -EOPNOTSUPP;
772 break;
773 }
774 /* If first try and runlist unmapped, map and retry. */
775 if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
776 is_retry = true;
777 /*
778 * Attempt to map runlist, dropping lock for
779 * the duration.
780 */
781 up_read(&ni->runlist.lock);
782 err = ntfs_map_runlist(ni, vcn);
783 if (likely(!err))
784 goto lock_retry_remap;
785 rl = NULL;
786 } else if (!rl)
787 up_read(&ni->runlist.lock);
788 /*
789 * If buffer is outside the runlist, truncate has cut it out
790 * of the runlist. Just clean and clear the buffer and set it
791 * uptodate so it can get discarded by the VM.
792 */
793 if (err == -ENOENT || lcn == LCN_ENOENT) {
794 bh->b_blocknr = -1;
795 clear_buffer_dirty(bh);
796 zero_user(page, bh_offset(bh), blocksize);
797 set_buffer_uptodate(bh);
798 err = 0;
799 continue;
800 }
801 /* Failed to map the buffer, even after retrying. */
802 if (!err)
803 err = -EIO;
804 bh->b_blocknr = -1;
805 ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
806 "attribute type 0x%x, vcn 0x%llx, offset 0x%x "
807 "because its location on disk could not be "
808 "determined%s (error code %i).", ni->mft_no,
809 ni->type, (unsigned long long)vcn,
810 vcn_ofs, is_retry ? " even after "
811 "retrying" : "", err);
812 break;
813 } while (block++, (bh = bh->b_this_page) != head);
814
815 /* Release the lock if we took it. */
816 if (rl)
817 up_read(&ni->runlist.lock);
818
819 /* For the error case, need to reset bh to the beginning. */
820 bh = head;
821
822 /* Just an optimization, so ->readpage() is not called later. */
823 if (unlikely(!PageUptodate(page))) {
824 int uptodate = 1;
825 do {
826 if (!buffer_uptodate(bh)) {
827 uptodate = 0;
828 bh = head;
829 break;
830 }
831 } while ((bh = bh->b_this_page) != head);
832 if (uptodate)
833 SetPageUptodate(page);
834 }
835
836 /* Setup all mapped, dirty buffers for async write i/o. */
837 do {
838 if (buffer_mapped(bh) && buffer_dirty(bh)) {
839 lock_buffer(bh);
840 if (test_clear_buffer_dirty(bh)) {
841 BUG_ON(!buffer_uptodate(bh));
842 mark_buffer_async_write(bh);
843 } else
844 unlock_buffer(bh);
845 } else if (unlikely(err)) {
846 /*
847 * For the error case. The buffer may have been set
848 * dirty during attachment to a dirty page.
849 */
850 if (err != -ENOMEM)
851 clear_buffer_dirty(bh);
852 }
853 } while ((bh = bh->b_this_page) != head);
854
855 if (unlikely(err)) {
856 // TODO: Remove the -EOPNOTSUPP check later on...
857 if (unlikely(err == -EOPNOTSUPP))
858 err = 0;
859 else if (err == -ENOMEM) {
860 ntfs_warning(vol->sb, "Error allocating memory. "
861 "Redirtying page so we try again "
862 "later.");
863 /*
864 * Put the page back on mapping->dirty_pages, but
865 * leave its buffer's dirty state as-is.
866 */
867 redirty_page_for_writepage(wbc, page);
868 err = 0;
869 } else
870 SetPageError(page);
871 }
872
873 BUG_ON(PageWriteback(page));
874 set_page_writeback(page); /* Keeps try_to_free_buffers() away. */
875
876 /* Submit the prepared buffers for i/o. */
877 need_end_writeback = true;
878 do {
879 struct buffer_head *next = bh->b_this_page;
880 if (buffer_async_write(bh)) {
881 submit_bh(WRITE, bh);
882 need_end_writeback = false;
883 }
884 bh = next;
885 } while (bh != head);
886 unlock_page(page);
887
888 /* If no i/o was started, need to end_page_writeback(). */
889 if (unlikely(need_end_writeback))
890 end_page_writeback(page);
891
892 ntfs_debug("Done.");
893 return err;
894}
895
896/**
897 * ntfs_write_mst_block - write a @page to the backing store
898 * @page: page cache page to write out
899 * @wbc: writeback control structure
900 *
901 * This function is for writing pages belonging to non-resident, mst protected
902 * attributes to their backing store. The only supported attributes are index
903 * allocation and $MFT/$DATA. Both directory inodes and index inodes are
904 * supported for the index allocation case.
905 *
906 * The page must remain locked for the duration of the write because we apply
907 * the mst fixups, write, and then undo the fixups, so if we were to unlock the
908 * page before undoing the fixups, any other user of the page will see the
909 * page contents as corrupt.
910 *
911 * We clear the page uptodate flag for the duration of the function to ensure
912 * exclusion for the $MFT/$DATA case against someone mapping an mft record we
913 * are about to apply the mst fixups to.
914 *
915 * Return 0 on success and -errno on error.
916 *
917 * Based on ntfs_write_block(), ntfs_mft_writepage(), and
918 * write_mft_record_nolock().
919 */
920static int ntfs_write_mst_block(struct page *page,
921 struct writeback_control *wbc)
922{
923 sector_t block, dblock, rec_block;
924 struct inode *vi = page->mapping->host;
925 ntfs_inode *ni = NTFS_I(vi);
926 ntfs_volume *vol = ni->vol;
927 u8 *kaddr;
928 unsigned int rec_size = ni->itype.index.block_size;
929 ntfs_inode *locked_nis[PAGE_CACHE_SIZE / rec_size];
930 struct buffer_head *bh, *head, *tbh, *rec_start_bh;
931 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
932 runlist_element *rl;
933 int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2;
934 unsigned bh_size, rec_size_bits;
935 bool sync, is_mft, page_is_dirty, rec_is_dirty;
936 unsigned char bh_size_bits;
937
938 ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
939 "0x%lx.", vi->i_ino, ni->type, page->index);
940 BUG_ON(!NInoNonResident(ni));
941 BUG_ON(!NInoMstProtected(ni));
942 is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino);
943 /*
944 * NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page
945 * in its page cache were to be marked dirty. However this should
946 * never happen with the current driver and considering we do not
947 * handle this case here we do want to BUG(), at least for now.
948 */
949 BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) ||
950 (NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION)));
951 bh_size = vol->sb->s_blocksize;
952 bh_size_bits = vol->sb->s_blocksize_bits;
953 max_bhs = PAGE_CACHE_SIZE / bh_size;
954 BUG_ON(!max_bhs);
955 BUG_ON(max_bhs > MAX_BUF_PER_PAGE);
956
957 /* Were we called for sync purposes? */
958 sync = (wbc->sync_mode == WB_SYNC_ALL);
959
960 /* Make sure we have mapped buffers. */
961 bh = head = page_buffers(page);
962 BUG_ON(!bh);
963
964 rec_size_bits = ni->itype.index.block_size_bits;
965 BUG_ON(!(PAGE_CACHE_SIZE >> rec_size_bits));
966 bhs_per_rec = rec_size >> bh_size_bits;
967 BUG_ON(!bhs_per_rec);
968
969 /* The first block in the page. */
970 rec_block = block = (sector_t)page->index <<
971 (PAGE_CACHE_SHIFT - bh_size_bits);
972
973 /* The first out of bounds block for the data size. */
974 dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits;
975
976 rl = NULL;
977 err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0;
978 page_is_dirty = rec_is_dirty = false;
979 rec_start_bh = NULL;
980 do {
981 bool is_retry = false;
982
983 if (likely(block < rec_block)) {
984 if (unlikely(block >= dblock)) {
985 clear_buffer_dirty(bh);
986 set_buffer_uptodate(bh);
987 continue;
988 }
989 /*
990 * This block is not the first one in the record. We
991 * ignore the buffer's dirty state because we could
992 * have raced with a parallel mark_ntfs_record_dirty().
993 */
994 if (!rec_is_dirty)
995 continue;
996 if (unlikely(err2)) {
997 if (err2 != -ENOMEM)
998 clear_buffer_dirty(bh);
999 continue;
1000 }
1001 } else /* if (block == rec_block) */ {
1002 BUG_ON(block > rec_block);
1003 /* This block is the first one in the record. */
1004 rec_block += bhs_per_rec;
1005 err2 = 0;
1006 if (unlikely(block >= dblock)) {
1007 clear_buffer_dirty(bh);
1008 continue;
1009 }
1010 if (!buffer_dirty(bh)) {
1011 /* Clean records are not written out. */
1012 rec_is_dirty = false;
1013 continue;
1014 }
1015 rec_is_dirty = true;
1016 rec_start_bh = bh;
1017 }
1018 /* Need to map the buffer if it is not mapped already. */
1019 if (unlikely(!buffer_mapped(bh))) {
1020 VCN vcn;
1021 LCN lcn;
1022 unsigned int vcn_ofs;
1023
1024 bh->b_bdev = vol->sb->s_bdev;
1025 /* Obtain the vcn and offset of the current block. */
1026 vcn = (VCN)block << bh_size_bits;
1027 vcn_ofs = vcn & vol->cluster_size_mask;
1028 vcn >>= vol->cluster_size_bits;
1029 if (!rl) {
1030lock_retry_remap:
1031 down_read(&ni->runlist.lock);
1032 rl = ni->runlist.rl;
1033 }
1034 if (likely(rl != NULL)) {
1035 /* Seek to element containing target vcn. */
1036 while (rl->length && rl[1].vcn <= vcn)
1037 rl++;
1038 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
1039 } else
1040 lcn = LCN_RL_NOT_MAPPED;
1041 /* Successful remap. */
1042 if (likely(lcn >= 0)) {
1043 /* Setup buffer head to correct block. */
1044 bh->b_blocknr = ((lcn <<
1045 vol->cluster_size_bits) +
1046 vcn_ofs) >> bh_size_bits;
1047 set_buffer_mapped(bh);
1048 } else {
1049 /*
1050 * Remap failed. Retry to map the runlist once
1051 * unless we are working on $MFT which always
1052 * has the whole of its runlist in memory.
1053 */
1054 if (!is_mft && !is_retry &&
1055 lcn == LCN_RL_NOT_MAPPED) {
1056 is_retry = true;
1057 /*
1058 * Attempt to map runlist, dropping
1059 * lock for the duration.
1060 */
1061 up_read(&ni->runlist.lock);
1062 err2 = ntfs_map_runlist(ni, vcn);
1063 if (likely(!err2))
1064 goto lock_retry_remap;
1065 if (err2 == -ENOMEM)
1066 page_is_dirty = true;
1067 lcn = err2;
1068 } else {
1069 err2 = -EIO;
1070 if (!rl)
1071 up_read(&ni->runlist.lock);
1072 }
1073 /* Hard error. Abort writing this record. */
1074 if (!err || err == -ENOMEM)
1075 err = err2;
1076 bh->b_blocknr = -1;
1077 ntfs_error(vol->sb, "Cannot write ntfs record "
1078 "0x%llx (inode 0x%lx, "
1079 "attribute type 0x%x) because "
1080 "its location on disk could "
1081 "not be determined (error "
1082 "code %lli).",
1083 (long long)block <<
1084 bh_size_bits >>
1085 vol->mft_record_size_bits,
1086 ni->mft_no, ni->type,
1087 (long long)lcn);
1088 /*
1089 * If this is not the first buffer, remove the
1090 * buffers in this record from the list of
1091 * buffers to write and clear their dirty bit
1092 * if not error -ENOMEM.
1093 */
1094 if (rec_start_bh != bh) {
1095 while (bhs[--nr_bhs] != rec_start_bh)
1096 ;
1097 if (err2 != -ENOMEM) {
1098 do {
1099 clear_buffer_dirty(
1100 rec_start_bh);
1101 } while ((rec_start_bh =
1102 rec_start_bh->
1103 b_this_page) !=
1104 bh);
1105 }
1106 }
1107 continue;
1108 }
1109 }
1110 BUG_ON(!buffer_uptodate(bh));
1111 BUG_ON(nr_bhs >= max_bhs);
1112 bhs[nr_bhs++] = bh;
1113 } while (block++, (bh = bh->b_this_page) != head);
1114 if (unlikely(rl))
1115 up_read(&ni->runlist.lock);
1116 /* If there were no dirty buffers, we are done. */
1117 if (!nr_bhs)
1118 goto done;
1119 /* Map the page so we can access its contents. */
1120 kaddr = kmap(page);
1121 /* Clear the page uptodate flag whilst the mst fixups are applied. */
1122 BUG_ON(!PageUptodate(page));
1123 ClearPageUptodate(page);
1124 for (i = 0; i < nr_bhs; i++) {
1125 unsigned int ofs;
1126
1127 /* Skip buffers which are not at the beginning of records. */
1128 if (i % bhs_per_rec)
1129 continue;
1130 tbh = bhs[i];
1131 ofs = bh_offset(tbh);
1132 if (is_mft) {
1133 ntfs_inode *tni;
1134 unsigned long mft_no;
1135
1136 /* Get the mft record number. */
1137 mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1138 >> rec_size_bits;
1139 /* Check whether to write this mft record. */
1140 tni = NULL;
1141 if (!ntfs_may_write_mft_record(vol, mft_no,
1142 (MFT_RECORD*)(kaddr + ofs), &tni)) {
1143 /*
1144 * The record should not be written. This
1145 * means we need to redirty the page before
1146 * returning.
1147 */
1148 page_is_dirty = true;
1149 /*
1150 * Remove the buffers in this mft record from
1151 * the list of buffers to write.
1152 */
1153 do {
1154 bhs[i] = NULL;
1155 } while (++i % bhs_per_rec);
1156 continue;
1157 }
1158 /*
1159 * The record should be written. If a locked ntfs
1160 * inode was returned, add it to the array of locked
1161 * ntfs inodes.
1162 */
1163 if (tni)
1164 locked_nis[nr_locked_nis++] = tni;
1165 }
1166 /* Apply the mst protection fixups. */
1167 err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs),
1168 rec_size);
1169 if (unlikely(err2)) {
1170 if (!err || err == -ENOMEM)
1171 err = -EIO;
1172 ntfs_error(vol->sb, "Failed to apply mst fixups "
1173 "(inode 0x%lx, attribute type 0x%x, "
1174 "page index 0x%lx, page offset 0x%x)!"
1175 " Unmount and run chkdsk.", vi->i_ino,
1176 ni->type, page->index, ofs);
1177 /*
1178 * Mark all the buffers in this record clean as we do
1179 * not want to write corrupt data to disk.
1180 */
1181 do {
1182 clear_buffer_dirty(bhs[i]);
1183 bhs[i] = NULL;
1184 } while (++i % bhs_per_rec);
1185 continue;
1186 }
1187 nr_recs++;
1188 }
1189 /* If no records are to be written out, we are done. */
1190 if (!nr_recs)
1191 goto unm_done;
1192 flush_dcache_page(page);
1193 /* Lock buffers and start synchronous write i/o on them. */
1194 for (i = 0; i < nr_bhs; i++) {
1195 tbh = bhs[i];
1196 if (!tbh)
1197 continue;
1198 if (!trylock_buffer(tbh))
1199 BUG();
1200 /* The buffer dirty state is now irrelevant, just clean it. */
1201 clear_buffer_dirty(tbh);
1202 BUG_ON(!buffer_uptodate(tbh));
1203 BUG_ON(!buffer_mapped(tbh));
1204 get_bh(tbh);
1205 tbh->b_end_io = end_buffer_write_sync;
1206 submit_bh(WRITE, tbh);
1207 }
1208 /* Synchronize the mft mirror now if not @sync. */
1209 if (is_mft && !sync)
1210 goto do_mirror;
1211do_wait:
1212 /* Wait on i/o completion of buffers. */
1213 for (i = 0; i < nr_bhs; i++) {
1214 tbh = bhs[i];
1215 if (!tbh)
1216 continue;
1217 wait_on_buffer(tbh);
1218 if (unlikely(!buffer_uptodate(tbh))) {
1219 ntfs_error(vol->sb, "I/O error while writing ntfs "
1220 "record buffer (inode 0x%lx, "
1221 "attribute type 0x%x, page index "
1222 "0x%lx, page offset 0x%lx)! Unmount "
1223 "and run chkdsk.", vi->i_ino, ni->type,
1224 page->index, bh_offset(tbh));
1225 if (!err || err == -ENOMEM)
1226 err = -EIO;
1227 /*
1228 * Set the buffer uptodate so the page and buffer
1229 * states do not become out of sync.
1230 */
1231 set_buffer_uptodate(tbh);
1232 }
1233 }
1234 /* If @sync, now synchronize the mft mirror. */
1235 if (is_mft && sync) {
1236do_mirror:
1237 for (i = 0; i < nr_bhs; i++) {
1238 unsigned long mft_no;
1239 unsigned int ofs;
1240
1241 /*
1242 * Skip buffers which are not at the beginning of
1243 * records.
1244 */
1245 if (i % bhs_per_rec)
1246 continue;
1247 tbh = bhs[i];
1248 /* Skip removed buffers (and hence records). */
1249 if (!tbh)
1250 continue;
1251 ofs = bh_offset(tbh);
1252 /* Get the mft record number. */
1253 mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1254 >> rec_size_bits;
1255 if (mft_no < vol->mftmirr_size)
1256 ntfs_sync_mft_mirror(vol, mft_no,
1257 (MFT_RECORD*)(kaddr + ofs),
1258 sync);
1259 }
1260 if (!sync)
1261 goto do_wait;
1262 }
1263 /* Remove the mst protection fixups again. */
1264 for (i = 0; i < nr_bhs; i++) {
1265 if (!(i % bhs_per_rec)) {
1266 tbh = bhs[i];
1267 if (!tbh)
1268 continue;
1269 post_write_mst_fixup((NTFS_RECORD*)(kaddr +
1270 bh_offset(tbh)));
1271 }
1272 }
1273 flush_dcache_page(page);
1274unm_done:
1275 /* Unlock any locked inodes. */
1276 while (nr_locked_nis-- > 0) {
1277 ntfs_inode *tni, *base_tni;
1278
1279 tni = locked_nis[nr_locked_nis];
1280 /* Get the base inode. */
1281 mutex_lock(&tni->extent_lock);
1282 if (tni->nr_extents >= 0)
1283 base_tni = tni;
1284 else {
1285 base_tni = tni->ext.base_ntfs_ino;
1286 BUG_ON(!base_tni);
1287 }
1288 mutex_unlock(&tni->extent_lock);
1289 ntfs_debug("Unlocking %s inode 0x%lx.",
1290 tni == base_tni ? "base" : "extent",
1291 tni->mft_no);
1292 mutex_unlock(&tni->mrec_lock);
1293 atomic_dec(&tni->count);
1294 iput(VFS_I(base_tni));
1295 }
1296 SetPageUptodate(page);
1297 kunmap(page);
1298done:
1299 if (unlikely(err && err != -ENOMEM)) {
1300 /*
1301 * Set page error if there is only one ntfs record in the page.
1302 * Otherwise we would loose per-record granularity.
1303 */
1304 if (ni->itype.index.block_size == PAGE_CACHE_SIZE)
1305 SetPageError(page);
1306 NVolSetErrors(vol);
1307 }
1308 if (page_is_dirty) {
1309 ntfs_debug("Page still contains one or more dirty ntfs "
1310 "records. Redirtying the page starting at "
1311 "record 0x%lx.", page->index <<
1312 (PAGE_CACHE_SHIFT - rec_size_bits));
1313 redirty_page_for_writepage(wbc, page);
1314 unlock_page(page);
1315 } else {
1316 /*
1317 * Keep the VM happy. This must be done otherwise the
1318 * radix-tree tag PAGECACHE_TAG_DIRTY remains set even though
1319 * the page is clean.
1320 */
1321 BUG_ON(PageWriteback(page));
1322 set_page_writeback(page);
1323 unlock_page(page);
1324 end_page_writeback(page);
1325 }
1326 if (likely(!err))
1327 ntfs_debug("Done.");
1328 return err;
1329}
1330
1331/**
1332 * ntfs_writepage - write a @page to the backing store
1333 * @page: page cache page to write out
1334 * @wbc: writeback control structure
1335 *
1336 * This is called from the VM when it wants to have a dirty ntfs page cache
1337 * page cleaned. The VM has already locked the page and marked it clean.
1338 *
1339 * For non-resident attributes, ntfs_writepage() writes the @page by calling
1340 * the ntfs version of the generic block_write_full_page() function,
1341 * ntfs_write_block(), which in turn if necessary creates and writes the
1342 * buffers associated with the page asynchronously.
1343 *
1344 * For resident attributes, OTOH, ntfs_writepage() writes the @page by copying
1345 * the data to the mft record (which at this stage is most likely in memory).
1346 * The mft record is then marked dirty and written out asynchronously via the
1347 * vfs inode dirty code path for the inode the mft record belongs to or via the
1348 * vm page dirty code path for the page the mft record is in.
1349 *
1350 * Based on ntfs_readpage() and fs/buffer.c::block_write_full_page().
1351 *
1352 * Return 0 on success and -errno on error.
1353 */
1354static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
1355{
1356 loff_t i_size;
1357 struct inode *vi = page->mapping->host;
1358 ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
1359 char *addr;
1360 ntfs_attr_search_ctx *ctx = NULL;
1361 MFT_RECORD *m = NULL;
1362 u32 attr_len;
1363 int err;
1364
1365retry_writepage:
1366 BUG_ON(!PageLocked(page));
1367 i_size = i_size_read(vi);
1368 /* Is the page fully outside i_size? (truncate in progress) */
1369 if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
1370 PAGE_CACHE_SHIFT)) {
1371 /*
1372 * The page may have dirty, unmapped buffers. Make them
1373 * freeable here, so the page does not leak.
1374 */
1375 block_invalidatepage(page, 0);
1376 unlock_page(page);
1377 ntfs_debug("Write outside i_size - truncated?");
1378 return 0;
1379 }
1380 /*
1381 * Only $DATA attributes can be encrypted and only unnamed $DATA
1382 * attributes can be compressed. Index root can have the flags set but
1383 * this means to create compressed/encrypted files, not that the
1384 * attribute is compressed/encrypted. Note we need to check for
1385 * AT_INDEX_ALLOCATION since this is the type of both directory and
1386 * index inodes.
1387 */
1388 if (ni->type != AT_INDEX_ALLOCATION) {
1389 /* If file is encrypted, deny access, just like NT4. */
1390 if (NInoEncrypted(ni)) {
1391 unlock_page(page);
1392 BUG_ON(ni->type != AT_DATA);
1393 ntfs_debug("Denying write access to encrypted file.");
1394 return -EACCES;
1395 }
1396 /* Compressed data streams are handled in compress.c. */
1397 if (NInoNonResident(ni) && NInoCompressed(ni)) {
1398 BUG_ON(ni->type != AT_DATA);
1399 BUG_ON(ni->name_len);
1400 // TODO: Implement and replace this with
1401 // return ntfs_write_compressed_block(page);
1402 unlock_page(page);
1403 ntfs_error(vi->i_sb, "Writing to compressed files is "
1404 "not supported yet. Sorry.");
1405 return -EOPNOTSUPP;
1406 }
1407 // TODO: Implement and remove this check.
1408 if (NInoNonResident(ni) && NInoSparse(ni)) {
1409 unlock_page(page);
1410 ntfs_error(vi->i_sb, "Writing to sparse files is not "
1411 "supported yet. Sorry.");
1412 return -EOPNOTSUPP;
1413 }
1414 }
1415 /* NInoNonResident() == NInoIndexAllocPresent() */
1416 if (NInoNonResident(ni)) {
1417 /* We have to zero every time due to mmap-at-end-of-file. */
1418 if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
1419 /* The page straddles i_size. */
1420 unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
1421 zero_user_segment(page, ofs, PAGE_CACHE_SIZE);
1422 }
1423 /* Handle mst protected attributes. */
1424 if (NInoMstProtected(ni))
1425 return ntfs_write_mst_block(page, wbc);
1426 /* Normal, non-resident data stream. */
1427 return ntfs_write_block(page, wbc);
1428 }
1429 /*
1430 * Attribute is resident, implying it is not compressed, encrypted, or
1431 * mst protected. This also means the attribute is smaller than an mft
1432 * record and hence smaller than a page, so can simply return error on
1433 * any pages with index above 0. Note the attribute can actually be
1434 * marked compressed but if it is resident the actual data is not
1435 * compressed so we are ok to ignore the compressed flag here.
1436 */
1437 BUG_ON(page_has_buffers(page));
1438 BUG_ON(!PageUptodate(page));
1439 if (unlikely(page->index > 0)) {
1440 ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0. "
1441 "Aborting write.", page->index);
1442 BUG_ON(PageWriteback(page));
1443 set_page_writeback(page);
1444 unlock_page(page);
1445 end_page_writeback(page);
1446 return -EIO;
1447 }
1448 if (!NInoAttr(ni))
1449 base_ni = ni;
1450 else
1451 base_ni = ni->ext.base_ntfs_ino;
1452 /* Map, pin, and lock the mft record. */
1453 m = map_mft_record(base_ni);
1454 if (IS_ERR(m)) {
1455 err = PTR_ERR(m);
1456 m = NULL;
1457 ctx = NULL;
1458 goto err_out;
1459 }
1460 /*
1461 * If a parallel write made the attribute non-resident, drop the mft
1462 * record and retry the writepage.
1463 */
1464 if (unlikely(NInoNonResident(ni))) {
1465 unmap_mft_record(base_ni);
1466 goto retry_writepage;
1467 }
1468 ctx = ntfs_attr_get_search_ctx(base_ni, m);
1469 if (unlikely(!ctx)) {
1470 err = -ENOMEM;
1471 goto err_out;
1472 }
1473 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1474 CASE_SENSITIVE, 0, NULL, 0, ctx);
1475 if (unlikely(err))
1476 goto err_out;
1477 /*
1478 * Keep the VM happy. This must be done otherwise the radix-tree tag
1479 * PAGECACHE_TAG_DIRTY remains set even though the page is clean.
1480 */
1481 BUG_ON(PageWriteback(page));
1482 set_page_writeback(page);
1483 unlock_page(page);
1484 attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
1485 i_size = i_size_read(vi);
1486 if (unlikely(attr_len > i_size)) {
1487 /* Race with shrinking truncate or a failed truncate. */
1488 attr_len = i_size;
1489 /*
1490 * If the truncate failed, fix it up now. If a concurrent
1491 * truncate, we do its job, so it does not have to do anything.
1492 */
1493 err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr,
1494 attr_len);
1495 /* Shrinking cannot fail. */
1496 BUG_ON(err);
1497 }
1498 addr = kmap_atomic(page);
1499 /* Copy the data from the page to the mft record. */
1500 memcpy((u8*)ctx->attr +
1501 le16_to_cpu(ctx->attr->data.resident.value_offset),
1502 addr, attr_len);
1503 /* Zero out of bounds area in the page cache page. */
1504 memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1505 kunmap_atomic(addr);
1506 flush_dcache_page(page);
1507 flush_dcache_mft_record_page(ctx->ntfs_ino);
1508 /* We are done with the page. */
1509 end_page_writeback(page);
1510 /* Finally, mark the mft record dirty, so it gets written back. */
1511 mark_mft_record_dirty(ctx->ntfs_ino);
1512 ntfs_attr_put_search_ctx(ctx);
1513 unmap_mft_record(base_ni);
1514 return 0;
1515err_out:
1516 if (err == -ENOMEM) {
1517 ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying "
1518 "page so we try again later.");
1519 /*
1520 * Put the page back on mapping->dirty_pages, but leave its
1521 * buffers' dirty state as-is.
1522 */
1523 redirty_page_for_writepage(wbc, page);
1524 err = 0;
1525 } else {
1526 ntfs_error(vi->i_sb, "Resident attribute write failed with "
1527 "error %i.", err);
1528 SetPageError(page);
1529 NVolSetErrors(ni->vol);
1530 }
1531 unlock_page(page);
1532 if (ctx)
1533 ntfs_attr_put_search_ctx(ctx);
1534 if (m)
1535 unmap_mft_record(base_ni);
1536 return err;
1537}
1538
1539#endif /* NTFS_RW */
1540
1541/**
1542 * ntfs_aops - general address space operations for inodes and attributes
1543 */
1544const struct address_space_operations ntfs_aops = {
1545 .readpage = ntfs_readpage, /* Fill page with data. */
1546#ifdef NTFS_RW
1547 .writepage = ntfs_writepage, /* Write dirty page to disk. */
1548#endif /* NTFS_RW */
1549 .migratepage = buffer_migrate_page, /* Move a page cache page from
1550 one physical page to an
1551 other. */
1552 .error_remove_page = generic_error_remove_page,
1553};
1554
1555/**
1556 * ntfs_mst_aops - general address space operations for mst protecteed inodes
1557 * and attributes
1558 */
1559const struct address_space_operations ntfs_mst_aops = {
1560 .readpage = ntfs_readpage, /* Fill page with data. */
1561#ifdef NTFS_RW
1562 .writepage = ntfs_writepage, /* Write dirty page to disk. */
1563 .set_page_dirty = __set_page_dirty_nobuffers, /* Set the page dirty
1564 without touching the buffers
1565 belonging to the page. */
1566#endif /* NTFS_RW */
1567 .migratepage = buffer_migrate_page, /* Move a page cache page from
1568 one physical page to an
1569 other. */
1570 .error_remove_page = generic_error_remove_page,
1571};
1572
1573#ifdef NTFS_RW
1574
1575/**
1576 * mark_ntfs_record_dirty - mark an ntfs record dirty
1577 * @page: page containing the ntfs record to mark dirty
1578 * @ofs: byte offset within @page at which the ntfs record begins
1579 *
1580 * Set the buffers and the page in which the ntfs record is located dirty.
1581 *
1582 * The latter also marks the vfs inode the ntfs record belongs to dirty
1583 * (I_DIRTY_PAGES only).
1584 *
1585 * If the page does not have buffers, we create them and set them uptodate.
1586 * The page may not be locked which is why we need to handle the buffers under
1587 * the mapping->private_lock. Once the buffers are marked dirty we no longer
1588 * need the lock since try_to_free_buffers() does not free dirty buffers.
1589 */
1590void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
1591 struct address_space *mapping = page->mapping;
1592 ntfs_inode *ni = NTFS_I(mapping->host);
1593 struct buffer_head *bh, *head, *buffers_to_free = NULL;
1594 unsigned int end, bh_size, bh_ofs;
1595
1596 BUG_ON(!PageUptodate(page));
1597 end = ofs + ni->itype.index.block_size;
1598 bh_size = VFS_I(ni)->i_sb->s_blocksize;
1599 spin_lock(&mapping->private_lock);
1600 if (unlikely(!page_has_buffers(page))) {
1601 spin_unlock(&mapping->private_lock);
1602 bh = head = alloc_page_buffers(page, bh_size, 1);
1603 spin_lock(&mapping->private_lock);
1604 if (likely(!page_has_buffers(page))) {
1605 struct buffer_head *tail;
1606
1607 do {
1608 set_buffer_uptodate(bh);
1609 tail = bh;
1610 bh = bh->b_this_page;
1611 } while (bh);
1612 tail->b_this_page = head;
1613 attach_page_buffers(page, head);
1614 } else
1615 buffers_to_free = bh;
1616 }
1617 bh = head = page_buffers(page);
1618 BUG_ON(!bh);
1619 do {
1620 bh_ofs = bh_offset(bh);
1621 if (bh_ofs + bh_size <= ofs)
1622 continue;
1623 if (unlikely(bh_ofs >= end))
1624 break;
1625 set_buffer_dirty(bh);
1626 } while ((bh = bh->b_this_page) != head);
1627 spin_unlock(&mapping->private_lock);
1628 __set_page_dirty_nobuffers(page);
1629 if (unlikely(buffers_to_free)) {
1630 do {
1631 bh = buffers_to_free->b_this_page;
1632 free_buffer_head(buffers_to_free);
1633 buffers_to_free = bh;
1634 } while (buffers_to_free);
1635 }
1636}
1637
1638#endif /* NTFS_RW */