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TOMOYO Linux Cross Reference
Linux/fs/ntfs/aops.c

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  1 /**
  2  * aops.c - NTFS kernel address space operations and page cache handling.
  3  *
  4  * Copyright (c) 2001-2014 Anton Altaparmakov and Tuxera Inc.
  5  * Copyright (c) 2002 Richard Russon
  6  *
  7  * This program/include file is free software; you can redistribute it and/or
  8  * modify it under the terms of the GNU General Public License as published
  9  * by the Free Software Foundation; either version 2 of the License, or
 10  * (at your option) any later version.
 11  *
 12  * This program/include file is distributed in the hope that it will be
 13  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15  * GNU General Public License for more details.
 16  *
 17  * You should have received a copy of the GNU General Public License
 18  * along with this program (in the main directory of the Linux-NTFS
 19  * distribution in the file COPYING); if not, write to the Free Software
 20  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 21  */
 22 
 23 #include <linux/errno.h>
 24 #include <linux/fs.h>
 25 #include <linux/gfp.h>
 26 #include <linux/mm.h>
 27 #include <linux/pagemap.h>
 28 #include <linux/swap.h>
 29 #include <linux/buffer_head.h>
 30 #include <linux/writeback.h>
 31 #include <linux/bit_spinlock.h>
 32 #include <linux/bio.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  */
 59 static 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_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                         kaddr = kmap_atomic(page);
 97                         memset(kaddr + bh_offset(bh) + ofs, 0,
 98                                         bh->b_size - ofs);
 99                         flush_dcache_page(page);
100                         kunmap_atomic(kaddr);
101                 }
102         } else {
103                 clear_buffer_uptodate(bh);
104                 SetPageError(page);
105                 ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
106                                 "0x%llx.", (unsigned long long)bh->b_blocknr);
107         }
108         first = page_buffers(page);
109         local_irq_save(flags);
110         bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
111         clear_buffer_async_read(bh);
112         unlock_buffer(bh);
113         tmp = bh;
114         do {
115                 if (!buffer_uptodate(tmp))
116                         page_uptodate = 0;
117                 if (buffer_async_read(tmp)) {
118                         if (likely(buffer_locked(tmp)))
119                                 goto still_busy;
120                         /* Async buffers must be locked. */
121                         BUG();
122                 }
123                 tmp = tmp->b_this_page;
124         } while (tmp != bh);
125         bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
126         local_irq_restore(flags);
127         /*
128          * If none of the buffers had errors then we can set the page uptodate,
129          * but we first have to perform the post read mst fixups, if the
130          * attribute is mst protected, i.e. if NInoMstProteced(ni) is true.
131          * Note we ignore fixup errors as those are detected when
132          * map_mft_record() is called which gives us per record granularity
133          * rather than per page granularity.
134          */
135         if (!NInoMstProtected(ni)) {
136                 if (likely(page_uptodate && !PageError(page)))
137                         SetPageUptodate(page);
138         } else {
139                 u8 *kaddr;
140                 unsigned int i, recs;
141                 u32 rec_size;
142 
143                 rec_size = ni->itype.index.block_size;
144                 recs = PAGE_SIZE / rec_size;
145                 /* Should have been verified before we got here... */
146                 BUG_ON(!recs);
147                 kaddr = kmap_atomic(page);
148                 for (i = 0; i < recs; i++)
149                         post_read_mst_fixup((NTFS_RECORD*)(kaddr +
150                                         i * rec_size), rec_size);
151                 kunmap_atomic(kaddr);
152                 flush_dcache_page(page);
153                 if (likely(page_uptodate && !PageError(page)))
154                         SetPageUptodate(page);
155         }
156         unlock_page(page);
157         return;
158 still_busy:
159         bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
160         local_irq_restore(flags);
161         return;
162 }
163 
164 /**
165  * ntfs_read_block - fill a @page of an address space with data
166  * @page:       page cache page to fill with data
167  *
168  * Fill the page @page of the address space belonging to the @page->host inode.
169  * We read each buffer asynchronously and when all buffers are read in, our io
170  * completion handler ntfs_end_buffer_read_async(), if required, automatically
171  * applies the mst fixups to the page before finally marking it uptodate and
172  * unlocking it.
173  *
174  * We only enforce allocated_size limit because i_size is checked for in
175  * generic_file_read().
176  *
177  * Return 0 on success and -errno on error.
178  *
179  * Contains an adapted version of fs/buffer.c::block_read_full_page().
180  */
181 static int ntfs_read_block(struct page *page)
182 {
183         loff_t i_size;
184         VCN vcn;
185         LCN lcn;
186         s64 init_size;
187         struct inode *vi;
188         ntfs_inode *ni;
189         ntfs_volume *vol;
190         runlist_element *rl;
191         struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
192         sector_t iblock, lblock, zblock;
193         unsigned long flags;
194         unsigned int blocksize, vcn_ofs;
195         int i, nr;
196         unsigned char blocksize_bits;
197 
198         vi = page->mapping->host;
199         ni = NTFS_I(vi);
200         vol = ni->vol;
201 
202         /* $MFT/$DATA must have its complete runlist in memory at all times. */
203         BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
204 
205         blocksize = vol->sb->s_blocksize;
206         blocksize_bits = vol->sb->s_blocksize_bits;
207 
208         if (!page_has_buffers(page)) {
209                 create_empty_buffers(page, blocksize, 0);
210                 if (unlikely(!page_has_buffers(page))) {
211                         unlock_page(page);
212                         return -ENOMEM;
213                 }
214         }
215         bh = head = page_buffers(page);
216         BUG_ON(!bh);
217 
218         /*
219          * We may be racing with truncate.  To avoid some of the problems we
220          * now take a snapshot of the various sizes and use those for the whole
221          * of the function.  In case of an extending truncate it just means we
222          * may leave some buffers unmapped which are now allocated.  This is
223          * not a problem since these buffers will just get mapped when a write
224          * occurs.  In case of a shrinking truncate, we will detect this later
225          * on due to the runlist being incomplete and if the page is being
226          * fully truncated, truncate will throw it away as soon as we unlock
227          * it so no need to worry what we do with it.
228          */
229         iblock = (s64)page->index << (PAGE_SHIFT - blocksize_bits);
230         read_lock_irqsave(&ni->size_lock, flags);
231         lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
232         init_size = ni->initialized_size;
233         i_size = i_size_read(vi);
234         read_unlock_irqrestore(&ni->size_lock, flags);
235         if (unlikely(init_size > i_size)) {
236                 /* Race with shrinking truncate. */
237                 init_size = i_size;
238         }
239         zblock = (init_size + blocksize - 1) >> blocksize_bits;
240 
241         /* Loop through all the buffers in the page. */
242         rl = NULL;
243         nr = i = 0;
244         do {
245                 int err = 0;
246 
247                 if (unlikely(buffer_uptodate(bh)))
248                         continue;
249                 if (unlikely(buffer_mapped(bh))) {
250                         arr[nr++] = bh;
251                         continue;
252                 }
253                 bh->b_bdev = vol->sb->s_bdev;
254                 /* Is the block within the allowed limits? */
255                 if (iblock < lblock) {
256                         bool is_retry = false;
257 
258                         /* Convert iblock into corresponding vcn and offset. */
259                         vcn = (VCN)iblock << blocksize_bits >>
260                                         vol->cluster_size_bits;
261                         vcn_ofs = ((VCN)iblock << blocksize_bits) &
262                                         vol->cluster_size_mask;
263                         if (!rl) {
264 lock_retry_remap:
265                                 down_read(&ni->runlist.lock);
266                                 rl = ni->runlist.rl;
267                         }
268                         if (likely(rl != NULL)) {
269                                 /* Seek to element containing target vcn. */
270                                 while (rl->length && rl[1].vcn <= vcn)
271                                         rl++;
272                                 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
273                         } else
274                                 lcn = LCN_RL_NOT_MAPPED;
275                         /* Successful remap. */
276                         if (lcn >= 0) {
277                                 /* Setup buffer head to correct block. */
278                                 bh->b_blocknr = ((lcn << vol->cluster_size_bits)
279                                                 + vcn_ofs) >> blocksize_bits;
280                                 set_buffer_mapped(bh);
281                                 /* Only read initialized data blocks. */
282                                 if (iblock < zblock) {
283                                         arr[nr++] = bh;
284                                         continue;
285                                 }
286                                 /* Fully non-initialized data block, zero it. */
287                                 goto handle_zblock;
288                         }
289                         /* It is a hole, need to zero it. */
290                         if (lcn == LCN_HOLE)
291                                 goto handle_hole;
292                         /* If first try and runlist unmapped, map and retry. */
293                         if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
294                                 is_retry = true;
295                                 /*
296                                  * Attempt to map runlist, dropping lock for
297                                  * the duration.
298                                  */
299                                 up_read(&ni->runlist.lock);
300                                 err = ntfs_map_runlist(ni, vcn);
301                                 if (likely(!err))
302                                         goto lock_retry_remap;
303                                 rl = NULL;
304                         } else if (!rl)
305                                 up_read(&ni->runlist.lock);
306                         /*
307                          * If buffer is outside the runlist, treat it as a
308                          * hole.  This can happen due to concurrent truncate
309                          * for example.
310                          */
311                         if (err == -ENOENT || lcn == LCN_ENOENT) {
312                                 err = 0;
313                                 goto handle_hole;
314                         }
315                         /* Hard error, zero out region. */
316                         if (!err)
317                                 err = -EIO;
318                         bh->b_blocknr = -1;
319                         SetPageError(page);
320                         ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
321                                         "attribute type 0x%x, vcn 0x%llx, "
322                                         "offset 0x%x because its location on "
323                                         "disk could not be determined%s "
324                                         "(error code %i).", ni->mft_no,
325                                         ni->type, (unsigned long long)vcn,
326                                         vcn_ofs, is_retry ? " even after "
327                                         "retrying" : "", err);
328                 }
329                 /*
330                  * Either iblock was outside lblock limits or
331                  * ntfs_rl_vcn_to_lcn() returned error.  Just zero that portion
332                  * of the page and set the buffer uptodate.
333                  */
334 handle_hole:
335                 bh->b_blocknr = -1UL;
336                 clear_buffer_mapped(bh);
337 handle_zblock:
338                 zero_user(page, i * blocksize, blocksize);
339                 if (likely(!err))
340                         set_buffer_uptodate(bh);
341         } while (i++, iblock++, (bh = bh->b_this_page) != head);
342 
343         /* Release the lock if we took it. */
344         if (rl)
345                 up_read(&ni->runlist.lock);
346 
347         /* Check we have at least one buffer ready for i/o. */
348         if (nr) {
349                 struct buffer_head *tbh;
350 
351                 /* Lock the buffers. */
352                 for (i = 0; i < nr; i++) {
353                         tbh = arr[i];
354                         lock_buffer(tbh);
355                         tbh->b_end_io = ntfs_end_buffer_async_read;
356                         set_buffer_async_read(tbh);
357                 }
358                 /* Finally, start i/o on the buffers. */
359                 for (i = 0; i < nr; i++) {
360                         tbh = arr[i];
361                         if (likely(!buffer_uptodate(tbh)))
362                                 submit_bh(REQ_OP_READ, 0, tbh);
363                         else
364                                 ntfs_end_buffer_async_read(tbh, 1);
365                 }
366                 return 0;
367         }
368         /* No i/o was scheduled on any of the buffers. */
369         if (likely(!PageError(page)))
370                 SetPageUptodate(page);
371         else /* Signal synchronous i/o error. */
372                 nr = -EIO;
373         unlock_page(page);
374         return nr;
375 }
376 
377 /**
378  * ntfs_readpage - fill a @page of a @file with data from the device
379  * @file:       open file to which the page @page belongs or NULL
380  * @page:       page cache page to fill with data
381  *
382  * For non-resident attributes, ntfs_readpage() fills the @page of the open
383  * file @file by calling the ntfs version of the generic block_read_full_page()
384  * function, ntfs_read_block(), which in turn creates and reads in the buffers
385  * associated with the page asynchronously.
386  *
387  * For resident attributes, OTOH, ntfs_readpage() fills @page by copying the
388  * data from the mft record (which at this stage is most likely in memory) and
389  * fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as
390  * even if the mft record is not cached at this point in time, we need to wait
391  * for it to be read in before we can do the copy.
392  *
393  * Return 0 on success and -errno on error.
394  */
395 static int ntfs_readpage(struct file *file, struct page *page)
396 {
397         loff_t i_size;
398         struct inode *vi;
399         ntfs_inode *ni, *base_ni;
400         u8 *addr;
401         ntfs_attr_search_ctx *ctx;
402         MFT_RECORD *mrec;
403         unsigned long flags;
404         u32 attr_len;
405         int err = 0;
406 
407 retry_readpage:
408         BUG_ON(!PageLocked(page));
409         vi = page->mapping->host;
410         i_size = i_size_read(vi);
411         /* Is the page fully outside i_size? (truncate in progress) */
412         if (unlikely(page->index >= (i_size + PAGE_SIZE - 1) >>
413                         PAGE_SHIFT)) {
414                 zero_user(page, 0, PAGE_SIZE);
415                 ntfs_debug("Read outside i_size - truncated?");
416                 goto done;
417         }
418         /*
419          * This can potentially happen because we clear PageUptodate() during
420          * ntfs_writepage() of MstProtected() attributes.
421          */
422         if (PageUptodate(page)) {
423                 unlock_page(page);
424                 return 0;
425         }
426         ni = NTFS_I(vi);
427         /*
428          * Only $DATA attributes can be encrypted and only unnamed $DATA
429          * attributes can be compressed.  Index root can have the flags set but
430          * this means to create compressed/encrypted files, not that the
431          * attribute is compressed/encrypted.  Note we need to check for
432          * AT_INDEX_ALLOCATION since this is the type of both directory and
433          * index inodes.
434          */
435         if (ni->type != AT_INDEX_ALLOCATION) {
436                 /* If attribute is encrypted, deny access, just like NT4. */
437                 if (NInoEncrypted(ni)) {
438                         BUG_ON(ni->type != AT_DATA);
439                         err = -EACCES;
440                         goto err_out;
441                 }
442                 /* Compressed data streams are handled in compress.c. */
443                 if (NInoNonResident(ni) && NInoCompressed(ni)) {
444                         BUG_ON(ni->type != AT_DATA);
445                         BUG_ON(ni->name_len);
446                         return ntfs_read_compressed_block(page);
447                 }
448         }
449         /* NInoNonResident() == NInoIndexAllocPresent() */
450         if (NInoNonResident(ni)) {
451                 /* Normal, non-resident data stream. */
452                 return ntfs_read_block(page);
453         }
454         /*
455          * Attribute is resident, implying it is not compressed or encrypted.
456          * This also means the attribute is smaller than an mft record and
457          * hence smaller than a page, so can simply zero out any pages with
458          * index above 0.  Note the attribute can actually be marked compressed
459          * but if it is resident the actual data is not compressed so we are
460          * ok to ignore the compressed flag here.
461          */
462         if (unlikely(page->index > 0)) {
463                 zero_user(page, 0, PAGE_SIZE);
464                 goto done;
465         }
466         if (!NInoAttr(ni))
467                 base_ni = ni;
468         else
469                 base_ni = ni->ext.base_ntfs_ino;
470         /* Map, pin, and lock the mft record. */
471         mrec = map_mft_record(base_ni);
472         if (IS_ERR(mrec)) {
473                 err = PTR_ERR(mrec);
474                 goto err_out;
475         }
476         /*
477          * If a parallel write made the attribute non-resident, drop the mft
478          * record and retry the readpage.
479          */
480         if (unlikely(NInoNonResident(ni))) {
481                 unmap_mft_record(base_ni);
482                 goto retry_readpage;
483         }
484         ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
485         if (unlikely(!ctx)) {
486                 err = -ENOMEM;
487                 goto unm_err_out;
488         }
489         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
490                         CASE_SENSITIVE, 0, NULL, 0, ctx);
491         if (unlikely(err))
492                 goto put_unm_err_out;
493         attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
494         read_lock_irqsave(&ni->size_lock, flags);
495         if (unlikely(attr_len > ni->initialized_size))
496                 attr_len = ni->initialized_size;
497         i_size = i_size_read(vi);
498         read_unlock_irqrestore(&ni->size_lock, flags);
499         if (unlikely(attr_len > i_size)) {
500                 /* Race with shrinking truncate. */
501                 attr_len = i_size;
502         }
503         addr = kmap_atomic(page);
504         /* Copy the data to the page. */
505         memcpy(addr, (u8*)ctx->attr +
506                         le16_to_cpu(ctx->attr->data.resident.value_offset),
507                         attr_len);
508         /* Zero the remainder of the page. */
509         memset(addr + attr_len, 0, PAGE_SIZE - attr_len);
510         flush_dcache_page(page);
511         kunmap_atomic(addr);
512 put_unm_err_out:
513         ntfs_attr_put_search_ctx(ctx);
514 unm_err_out:
515         unmap_mft_record(base_ni);
516 done:
517         SetPageUptodate(page);
518 err_out:
519         unlock_page(page);
520         return err;
521 }
522 
523 #ifdef NTFS_RW
524 
525 /**
526  * ntfs_write_block - write a @page to the backing store
527  * @page:       page cache page to write out
528  * @wbc:        writeback control structure
529  *
530  * This function is for writing pages belonging to non-resident, non-mst
531  * protected attributes to their backing store.
532  *
533  * For a page with buffers, map and write the dirty buffers asynchronously
534  * under page writeback. For a page without buffers, create buffers for the
535  * page, then proceed as above.
536  *
537  * If a page doesn't have buffers the page dirty state is definitive. If a page
538  * does have buffers, the page dirty state is just a hint, and the buffer dirty
539  * state is definitive. (A hint which has rules: dirty buffers against a clean
540  * page is illegal. Other combinations are legal and need to be handled. In
541  * particular a dirty page containing clean buffers for example.)
542  *
543  * Return 0 on success and -errno on error.
544  *
545  * Based on ntfs_read_block() and __block_write_full_page().
546  */
547 static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
548 {
549         VCN vcn;
550         LCN lcn;
551         s64 initialized_size;
552         loff_t i_size;
553         sector_t block, dblock, iblock;
554         struct inode *vi;
555         ntfs_inode *ni;
556         ntfs_volume *vol;
557         runlist_element *rl;
558         struct buffer_head *bh, *head;
559         unsigned long flags;
560         unsigned int blocksize, vcn_ofs;
561         int err;
562         bool need_end_writeback;
563         unsigned char blocksize_bits;
564 
565         vi = page->mapping->host;
566         ni = NTFS_I(vi);
567         vol = ni->vol;
568 
569         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
570                         "0x%lx.", ni->mft_no, ni->type, page->index);
571 
572         BUG_ON(!NInoNonResident(ni));
573         BUG_ON(NInoMstProtected(ni));
574         blocksize = vol->sb->s_blocksize;
575         blocksize_bits = vol->sb->s_blocksize_bits;
576         if (!page_has_buffers(page)) {
577                 BUG_ON(!PageUptodate(page));
578                 create_empty_buffers(page, blocksize,
579                                 (1 << BH_Uptodate) | (1 << BH_Dirty));
580                 if (unlikely(!page_has_buffers(page))) {
581                         ntfs_warning(vol->sb, "Error allocating page "
582                                         "buffers.  Redirtying page so we try "
583                                         "again later.");
584                         /*
585                          * Put the page back on mapping->dirty_pages, but leave
586                          * its buffers' dirty state as-is.
587                          */
588                         redirty_page_for_writepage(wbc, page);
589                         unlock_page(page);
590                         return 0;
591                 }
592         }
593         bh = head = page_buffers(page);
594         BUG_ON(!bh);
595 
596         /* NOTE: Different naming scheme to ntfs_read_block()! */
597 
598         /* The first block in the page. */
599         block = (s64)page->index << (PAGE_SHIFT - blocksize_bits);
600 
601         read_lock_irqsave(&ni->size_lock, flags);
602         i_size = i_size_read(vi);
603         initialized_size = ni->initialized_size;
604         read_unlock_irqrestore(&ni->size_lock, flags);
605 
606         /* The first out of bounds block for the data size. */
607         dblock = (i_size + blocksize - 1) >> blocksize_bits;
608 
609         /* The last (fully or partially) initialized block. */
610         iblock = initialized_size >> blocksize_bits;
611 
612         /*
613          * Be very careful.  We have no exclusion from __set_page_dirty_buffers
614          * here, and the (potentially unmapped) buffers may become dirty at
615          * any time.  If a buffer becomes dirty here after we've inspected it
616          * then we just miss that fact, and the page stays dirty.
617          *
618          * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
619          * handle that here by just cleaning them.
620          */
621 
622         /*
623          * Loop through all the buffers in the page, mapping all the dirty
624          * buffers to disk addresses and handling any aliases from the
625          * underlying block device's mapping.
626          */
627         rl = NULL;
628         err = 0;
629         do {
630                 bool is_retry = false;
631 
632                 if (unlikely(block >= dblock)) {
633                         /*
634                          * Mapped buffers outside i_size will occur, because
635                          * this page can be outside i_size when there is a
636                          * truncate in progress. The contents of such buffers
637                          * were zeroed by ntfs_writepage().
638                          *
639                          * FIXME: What about the small race window where
640                          * ntfs_writepage() has not done any clearing because
641                          * the page was within i_size but before we get here,
642                          * vmtruncate() modifies i_size?
643                          */
644                         clear_buffer_dirty(bh);
645                         set_buffer_uptodate(bh);
646                         continue;
647                 }
648 
649                 /* Clean buffers are not written out, so no need to map them. */
650                 if (!buffer_dirty(bh))
651                         continue;
652 
653                 /* Make sure we have enough initialized size. */
654                 if (unlikely((block >= iblock) &&
655                                 (initialized_size < i_size))) {
656                         /*
657                          * If this page is fully outside initialized size, zero
658                          * out all pages between the current initialized size
659                          * and the current page. Just use ntfs_readpage() to do
660                          * the zeroing transparently.
661                          */
662                         if (block > iblock) {
663                                 // TODO:
664                                 // For each page do:
665                                 // - read_cache_page()
666                                 // Again for each page do:
667                                 // - wait_on_page_locked()
668                                 // - Check (PageUptodate(page) &&
669                                 //                      !PageError(page))
670                                 // Update initialized size in the attribute and
671                                 // in the inode.
672                                 // Again, for each page do:
673                                 //      __set_page_dirty_buffers();
674                                 // put_page()
675                                 // We don't need to wait on the writes.
676                                 // Update iblock.
677                         }
678                         /*
679                          * The current page straddles initialized size. Zero
680                          * all non-uptodate buffers and set them uptodate (and
681                          * dirty?). Note, there aren't any non-uptodate buffers
682                          * if the page is uptodate.
683                          * FIXME: For an uptodate page, the buffers may need to
684                          * be written out because they were not initialized on
685                          * disk before.
686                          */
687                         if (!PageUptodate(page)) {
688                                 // TODO:
689                                 // Zero any non-uptodate buffers up to i_size.
690                                 // Set them uptodate and dirty.
691                         }
692                         // TODO:
693                         // Update initialized size in the attribute and in the
694                         // inode (up to i_size).
695                         // Update iblock.
696                         // FIXME: This is inefficient. Try to batch the two
697                         // size changes to happen in one go.
698                         ntfs_error(vol->sb, "Writing beyond initialized size "
699                                         "is not supported yet. Sorry.");
700                         err = -EOPNOTSUPP;
701                         break;
702                         // Do NOT set_buffer_new() BUT DO clear buffer range
703                         // outside write request range.
704                         // set_buffer_uptodate() on complete buffers as well as
705                         // set_buffer_dirty().
706                 }
707 
708                 /* No need to map buffers that are already mapped. */
709                 if (buffer_mapped(bh))
710                         continue;
711 
712                 /* Unmapped, dirty buffer. Need to map it. */
713                 bh->b_bdev = vol->sb->s_bdev;
714 
715                 /* Convert block into corresponding vcn and offset. */
716                 vcn = (VCN)block << blocksize_bits;
717                 vcn_ofs = vcn & vol->cluster_size_mask;
718                 vcn >>= vol->cluster_size_bits;
719                 if (!rl) {
720 lock_retry_remap:
721                         down_read(&ni->runlist.lock);
722                         rl = ni->runlist.rl;
723                 }
724                 if (likely(rl != NULL)) {
725                         /* Seek to element containing target vcn. */
726                         while (rl->length && rl[1].vcn <= vcn)
727                                 rl++;
728                         lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
729                 } else
730                         lcn = LCN_RL_NOT_MAPPED;
731                 /* Successful remap. */
732                 if (lcn >= 0) {
733                         /* Setup buffer head to point to correct block. */
734                         bh->b_blocknr = ((lcn << vol->cluster_size_bits) +
735                                         vcn_ofs) >> blocksize_bits;
736                         set_buffer_mapped(bh);
737                         continue;
738                 }
739                 /* It is a hole, need to instantiate it. */
740                 if (lcn == LCN_HOLE) {
741                         u8 *kaddr;
742                         unsigned long *bpos, *bend;
743 
744                         /* Check if the buffer is zero. */
745                         kaddr = kmap_atomic(page);
746                         bpos = (unsigned long *)(kaddr + bh_offset(bh));
747                         bend = (unsigned long *)((u8*)bpos + blocksize);
748                         do {
749                                 if (unlikely(*bpos))
750                                         break;
751                         } while (likely(++bpos < bend));
752                         kunmap_atomic(kaddr);
753                         if (bpos == bend) {
754                                 /*
755                                  * Buffer is zero and sparse, no need to write
756                                  * it.
757                                  */
758                                 bh->b_blocknr = -1;
759                                 clear_buffer_dirty(bh);
760                                 continue;
761                         }
762                         // TODO: Instantiate the hole.
763                         // clear_buffer_new(bh);
764                         // clean_bdev_bh_alias(bh);
765                         ntfs_error(vol->sb, "Writing into sparse regions is "
766                                         "not supported yet. Sorry.");
767                         err = -EOPNOTSUPP;
768                         break;
769                 }
770                 /* If first try and runlist unmapped, map and retry. */
771                 if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
772                         is_retry = true;
773                         /*
774                          * Attempt to map runlist, dropping lock for
775                          * the duration.
776                          */
777                         up_read(&ni->runlist.lock);
778                         err = ntfs_map_runlist(ni, vcn);
779                         if (likely(!err))
780                                 goto lock_retry_remap;
781                         rl = NULL;
782                 } else if (!rl)
783                         up_read(&ni->runlist.lock);
784                 /*
785                  * If buffer is outside the runlist, truncate has cut it out
786                  * of the runlist.  Just clean and clear the buffer and set it
787                  * uptodate so it can get discarded by the VM.
788                  */
789                 if (err == -ENOENT || lcn == LCN_ENOENT) {
790                         bh->b_blocknr = -1;
791                         clear_buffer_dirty(bh);
792                         zero_user(page, bh_offset(bh), blocksize);
793                         set_buffer_uptodate(bh);
794                         err = 0;
795                         continue;
796                 }
797                 /* Failed to map the buffer, even after retrying. */
798                 if (!err)
799                         err = -EIO;
800                 bh->b_blocknr = -1;
801                 ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
802                                 "attribute type 0x%x, vcn 0x%llx, offset 0x%x "
803                                 "because its location on disk could not be "
804                                 "determined%s (error code %i).", ni->mft_no,
805                                 ni->type, (unsigned long long)vcn,
806                                 vcn_ofs, is_retry ? " even after "
807                                 "retrying" : "", err);
808                 break;
809         } while (block++, (bh = bh->b_this_page) != head);
810 
811         /* Release the lock if we took it. */
812         if (rl)
813                 up_read(&ni->runlist.lock);
814 
815         /* For the error case, need to reset bh to the beginning. */
816         bh = head;
817 
818         /* Just an optimization, so ->readpage() is not called later. */
819         if (unlikely(!PageUptodate(page))) {
820                 int uptodate = 1;
821                 do {
822                         if (!buffer_uptodate(bh)) {
823                                 uptodate = 0;
824                                 bh = head;
825                                 break;
826                         }
827                 } while ((bh = bh->b_this_page) != head);
828                 if (uptodate)
829                         SetPageUptodate(page);
830         }
831 
832         /* Setup all mapped, dirty buffers for async write i/o. */
833         do {
834                 if (buffer_mapped(bh) && buffer_dirty(bh)) {
835                         lock_buffer(bh);
836                         if (test_clear_buffer_dirty(bh)) {
837                                 BUG_ON(!buffer_uptodate(bh));
838                                 mark_buffer_async_write(bh);
839                         } else
840                                 unlock_buffer(bh);
841                 } else if (unlikely(err)) {
842                         /*
843                          * For the error case. The buffer may have been set
844                          * dirty during attachment to a dirty page.
845                          */
846                         if (err != -ENOMEM)
847                                 clear_buffer_dirty(bh);
848                 }
849         } while ((bh = bh->b_this_page) != head);
850 
851         if (unlikely(err)) {
852                 // TODO: Remove the -EOPNOTSUPP check later on...
853                 if (unlikely(err == -EOPNOTSUPP))
854                         err = 0;
855                 else if (err == -ENOMEM) {
856                         ntfs_warning(vol->sb, "Error allocating memory. "
857                                         "Redirtying page so we try again "
858                                         "later.");
859                         /*
860                          * Put the page back on mapping->dirty_pages, but
861                          * leave its buffer's dirty state as-is.
862                          */
863                         redirty_page_for_writepage(wbc, page);
864                         err = 0;
865                 } else
866                         SetPageError(page);
867         }
868 
869         BUG_ON(PageWriteback(page));
870         set_page_writeback(page);       /* Keeps try_to_free_buffers() away. */
871 
872         /* Submit the prepared buffers for i/o. */
873         need_end_writeback = true;
874         do {
875                 struct buffer_head *next = bh->b_this_page;
876                 if (buffer_async_write(bh)) {
877                         submit_bh(REQ_OP_WRITE, 0, bh);
878                         need_end_writeback = false;
879                 }
880                 bh = next;
881         } while (bh != head);
882         unlock_page(page);
883 
884         /* If no i/o was started, need to end_page_writeback(). */
885         if (unlikely(need_end_writeback))
886                 end_page_writeback(page);
887 
888         ntfs_debug("Done.");
889         return err;
890 }
891 
892 /**
893  * ntfs_write_mst_block - write a @page to the backing store
894  * @page:       page cache page to write out
895  * @wbc:        writeback control structure
896  *
897  * This function is for writing pages belonging to non-resident, mst protected
898  * attributes to their backing store.  The only supported attributes are index
899  * allocation and $MFT/$DATA.  Both directory inodes and index inodes are
900  * supported for the index allocation case.
901  *
902  * The page must remain locked for the duration of the write because we apply
903  * the mst fixups, write, and then undo the fixups, so if we were to unlock the
904  * page before undoing the fixups, any other user of the page will see the
905  * page contents as corrupt.
906  *
907  * We clear the page uptodate flag for the duration of the function to ensure
908  * exclusion for the $MFT/$DATA case against someone mapping an mft record we
909  * are about to apply the mst fixups to.
910  *
911  * Return 0 on success and -errno on error.
912  *
913  * Based on ntfs_write_block(), ntfs_mft_writepage(), and
914  * write_mft_record_nolock().
915  */
916 static int ntfs_write_mst_block(struct page *page,
917                 struct writeback_control *wbc)
918 {
919         sector_t block, dblock, rec_block;
920         struct inode *vi = page->mapping->host;
921         ntfs_inode *ni = NTFS_I(vi);
922         ntfs_volume *vol = ni->vol;
923         u8 *kaddr;
924         unsigned int rec_size = ni->itype.index.block_size;
925         ntfs_inode *locked_nis[PAGE_SIZE / NTFS_BLOCK_SIZE];
926         struct buffer_head *bh, *head, *tbh, *rec_start_bh;
927         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
928         runlist_element *rl;
929         int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2;
930         unsigned bh_size, rec_size_bits;
931         bool sync, is_mft, page_is_dirty, rec_is_dirty;
932         unsigned char bh_size_bits;
933 
934         if (WARN_ON(rec_size < NTFS_BLOCK_SIZE))
935                 return -EINVAL;
936 
937         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
938                         "0x%lx.", vi->i_ino, ni->type, page->index);
939         BUG_ON(!NInoNonResident(ni));
940         BUG_ON(!NInoMstProtected(ni));
941         is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino);
942         /*
943          * NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page
944          * in its page cache were to be marked dirty.  However this should
945          * never happen with the current driver and considering we do not
946          * handle this case here we do want to BUG(), at least for now.
947          */
948         BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) ||
949                         (NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION)));
950         bh_size = vol->sb->s_blocksize;
951         bh_size_bits = vol->sb->s_blocksize_bits;
952         max_bhs = PAGE_SIZE / bh_size;
953         BUG_ON(!max_bhs);
954         BUG_ON(max_bhs > MAX_BUF_PER_PAGE);
955 
956         /* Were we called for sync purposes? */
957         sync = (wbc->sync_mode == WB_SYNC_ALL);
958 
959         /* Make sure we have mapped buffers. */
960         bh = head = page_buffers(page);
961         BUG_ON(!bh);
962 
963         rec_size_bits = ni->itype.index.block_size_bits;
964         BUG_ON(!(PAGE_SIZE >> rec_size_bits));
965         bhs_per_rec = rec_size >> bh_size_bits;
966         BUG_ON(!bhs_per_rec);
967 
968         /* The first block in the page. */
969         rec_block = block = (sector_t)page->index <<
970                         (PAGE_SHIFT - bh_size_bits);
971 
972         /* The first out of bounds block for the data size. */
973         dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits;
974 
975         rl = NULL;
976         err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0;
977         page_is_dirty = rec_is_dirty = false;
978         rec_start_bh = NULL;
979         do {
980                 bool is_retry = false;
981 
982                 if (likely(block < rec_block)) {
983                         if (unlikely(block >= dblock)) {
984                                 clear_buffer_dirty(bh);
985                                 set_buffer_uptodate(bh);
986                                 continue;
987                         }
988                         /*
989                          * This block is not the first one in the record.  We
990                          * ignore the buffer's dirty state because we could
991                          * have raced with a parallel mark_ntfs_record_dirty().
992                          */
993                         if (!rec_is_dirty)
994                                 continue;
995                         if (unlikely(err2)) {
996                                 if (err2 != -ENOMEM)
997                                         clear_buffer_dirty(bh);
998                                 continue;
999                         }
1000                 } else /* if (block == rec_block) */ {
1001                         BUG_ON(block > rec_block);
1002                         /* This block is the first one in the record. */
1003                         rec_block += bhs_per_rec;
1004                         err2 = 0;
1005                         if (unlikely(block >= dblock)) {
1006                                 clear_buffer_dirty(bh);
1007                                 continue;
1008                         }
1009                         if (!buffer_dirty(bh)) {
1010                                 /* Clean records are not written out. */
1011                                 rec_is_dirty = false;
1012                                 continue;
1013                         }
1014                         rec_is_dirty = true;
1015                         rec_start_bh = bh;
1016                 }
1017                 /* Need to map the buffer if it is not mapped already. */
1018                 if (unlikely(!buffer_mapped(bh))) {
1019                         VCN vcn;
1020                         LCN lcn;
1021                         unsigned int vcn_ofs;
1022 
1023                         bh->b_bdev = vol->sb->s_bdev;
1024                         /* Obtain the vcn and offset of the current block. */
1025                         vcn = (VCN)block << bh_size_bits;
1026                         vcn_ofs = vcn & vol->cluster_size_mask;
1027                         vcn >>= vol->cluster_size_bits;
1028                         if (!rl) {
1029 lock_retry_remap:
1030                                 down_read(&ni->runlist.lock);
1031                                 rl = ni->runlist.rl;
1032                         }
1033                         if (likely(rl != NULL)) {
1034                                 /* Seek to element containing target vcn. */
1035                                 while (rl->length && rl[1].vcn <= vcn)
1036                                         rl++;
1037                                 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
1038                         } else
1039                                 lcn = LCN_RL_NOT_MAPPED;
1040                         /* Successful remap. */
1041                         if (likely(lcn >= 0)) {
1042                                 /* Setup buffer head to correct block. */
1043                                 bh->b_blocknr = ((lcn <<
1044                                                 vol->cluster_size_bits) +
1045                                                 vcn_ofs) >> bh_size_bits;
1046                                 set_buffer_mapped(bh);
1047                         } else {
1048                                 /*
1049                                  * Remap failed.  Retry to map the runlist once
1050                                  * unless we are working on $MFT which always
1051                                  * has the whole of its runlist in memory.
1052                                  */
1053                                 if (!is_mft && !is_retry &&
1054                                                 lcn == LCN_RL_NOT_MAPPED) {
1055                                         is_retry = true;
1056                                         /*
1057                                          * Attempt to map runlist, dropping
1058                                          * lock for the duration.
1059                                          */
1060                                         up_read(&ni->runlist.lock);
1061                                         err2 = ntfs_map_runlist(ni, vcn);
1062                                         if (likely(!err2))
1063                                                 goto lock_retry_remap;
1064                                         if (err2 == -ENOMEM)
1065                                                 page_is_dirty = true;
1066                                         lcn = err2;
1067                                 } else {
1068                                         err2 = -EIO;
1069                                         if (!rl)
1070                                                 up_read(&ni->runlist.lock);
1071                                 }
1072                                 /* Hard error.  Abort writing this record. */
1073                                 if (!err || err == -ENOMEM)
1074                                         err = err2;
1075                                 bh->b_blocknr = -1;
1076                                 ntfs_error(vol->sb, "Cannot write ntfs record "
1077                                                 "0x%llx (inode 0x%lx, "
1078                                                 "attribute type 0x%x) because "
1079                                                 "its location on disk could "
1080                                                 "not be determined (error "
1081                                                 "code %lli).",
1082                                                 (long long)block <<
1083                                                 bh_size_bits >>
1084                                                 vol->mft_record_size_bits,
1085                                                 ni->mft_no, ni->type,
1086                                                 (long long)lcn);
1087                                 /*
1088                                  * If this is not the first buffer, remove the
1089                                  * buffers in this record from the list of
1090                                  * buffers to write and clear their dirty bit
1091                                  * if not error -ENOMEM.
1092                                  */
1093                                 if (rec_start_bh != bh) {
1094                                         while (bhs[--nr_bhs] != rec_start_bh)
1095                                                 ;
1096                                         if (err2 != -ENOMEM) {
1097                                                 do {
1098                                                         clear_buffer_dirty(
1099                                                                 rec_start_bh);
1100                                                 } while ((rec_start_bh =
1101                                                                 rec_start_bh->
1102                                                                 b_this_page) !=
1103                                                                 bh);
1104                                         }
1105                                 }
1106                                 continue;
1107                         }
1108                 }
1109                 BUG_ON(!buffer_uptodate(bh));
1110                 BUG_ON(nr_bhs >= max_bhs);
1111                 bhs[nr_bhs++] = bh;
1112         } while (block++, (bh = bh->b_this_page) != head);
1113         if (unlikely(rl))
1114                 up_read(&ni->runlist.lock);
1115         /* If there were no dirty buffers, we are done. */
1116         if (!nr_bhs)
1117                 goto done;
1118         /* Map the page so we can access its contents. */
1119         kaddr = kmap(page);
1120         /* Clear the page uptodate flag whilst the mst fixups are applied. */
1121         BUG_ON(!PageUptodate(page));
1122         ClearPageUptodate(page);
1123         for (i = 0; i < nr_bhs; i++) {
1124                 unsigned int ofs;
1125 
1126                 /* Skip buffers which are not at the beginning of records. */
1127                 if (i % bhs_per_rec)
1128                         continue;
1129                 tbh = bhs[i];
1130                 ofs = bh_offset(tbh);
1131                 if (is_mft) {
1132                         ntfs_inode *tni;
1133                         unsigned long mft_no;
1134 
1135                         /* Get the mft record number. */
1136                         mft_no = (((s64)page->index << PAGE_SHIFT) + ofs)
1137                                         >> rec_size_bits;
1138                         /* Check whether to write this mft record. */
1139                         tni = NULL;
1140                         if (!ntfs_may_write_mft_record(vol, mft_no,
1141                                         (MFT_RECORD*)(kaddr + ofs), &tni)) {
1142                                 /*
1143                                  * The record should not be written.  This
1144                                  * means we need to redirty the page before
1145                                  * returning.
1146                                  */
1147                                 page_is_dirty = true;
1148                                 /*
1149                                  * Remove the buffers in this mft record from
1150                                  * the list of buffers to write.
1151                                  */
1152                                 do {
1153                                         bhs[i] = NULL;
1154                                 } while (++i % bhs_per_rec);
1155                                 continue;
1156                         }
1157                         /*
1158                          * The record should be written.  If a locked ntfs
1159                          * inode was returned, add it to the array of locked
1160                          * ntfs inodes.
1161                          */
1162                         if (tni)
1163                                 locked_nis[nr_locked_nis++] = tni;
1164                 }
1165                 /* Apply the mst protection fixups. */
1166                 err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs),
1167                                 rec_size);
1168                 if (unlikely(err2)) {
1169                         if (!err || err == -ENOMEM)
1170                                 err = -EIO;
1171                         ntfs_error(vol->sb, "Failed to apply mst fixups "
1172                                         "(inode 0x%lx, attribute type 0x%x, "
1173                                         "page index 0x%lx, page offset 0x%x)!"
1174                                         "  Unmount and run chkdsk.", vi->i_ino,
1175                                         ni->type, page->index, ofs);
1176                         /*
1177                          * Mark all the buffers in this record clean as we do
1178                          * not want to write corrupt data to disk.
1179                          */
1180                         do {
1181                                 clear_buffer_dirty(bhs[i]);
1182                                 bhs[i] = NULL;
1183                         } while (++i % bhs_per_rec);
1184                         continue;
1185                 }
1186                 nr_recs++;
1187         }
1188         /* If no records are to be written out, we are done. */
1189         if (!nr_recs)
1190                 goto unm_done;
1191         flush_dcache_page(page);
1192         /* Lock buffers and start synchronous write i/o on them. */
1193         for (i = 0; i < nr_bhs; i++) {
1194                 tbh = bhs[i];
1195                 if (!tbh)
1196                         continue;
1197                 if (!trylock_buffer(tbh))
1198                         BUG();
1199                 /* The buffer dirty state is now irrelevant, just clean it. */
1200                 clear_buffer_dirty(tbh);
1201                 BUG_ON(!buffer_uptodate(tbh));
1202                 BUG_ON(!buffer_mapped(tbh));
1203                 get_bh(tbh);
1204                 tbh->b_end_io = end_buffer_write_sync;
1205                 submit_bh(REQ_OP_WRITE, 0, tbh);
1206         }
1207         /* Synchronize the mft mirror now if not @sync. */
1208         if (is_mft && !sync)
1209                 goto do_mirror;
1210 do_wait:
1211         /* Wait on i/o completion of buffers. */
1212         for (i = 0; i < nr_bhs; i++) {
1213                 tbh = bhs[i];
1214                 if (!tbh)
1215                         continue;
1216                 wait_on_buffer(tbh);
1217                 if (unlikely(!buffer_uptodate(tbh))) {
1218                         ntfs_error(vol->sb, "I/O error while writing ntfs "
1219                                         "record buffer (inode 0x%lx, "
1220                                         "attribute type 0x%x, page index "
1221                                         "0x%lx, page offset 0x%lx)!  Unmount "
1222                                         "and run chkdsk.", vi->i_ino, ni->type,
1223                                         page->index, bh_offset(tbh));
1224                         if (!err || err == -ENOMEM)
1225                                 err = -EIO;
1226                         /*
1227                          * Set the buffer uptodate so the page and buffer
1228                          * states do not become out of sync.
1229                          */
1230                         set_buffer_uptodate(tbh);
1231                 }
1232         }
1233         /* If @sync, now synchronize the mft mirror. */
1234         if (is_mft && sync) {
1235 do_mirror:
1236                 for (i = 0; i < nr_bhs; i++) {
1237                         unsigned long mft_no;
1238                         unsigned int ofs;
1239 
1240                         /*
1241                          * Skip buffers which are not at the beginning of
1242                          * records.
1243                          */
1244                         if (i % bhs_per_rec)
1245                                 continue;
1246                         tbh = bhs[i];
1247                         /* Skip removed buffers (and hence records). */
1248                         if (!tbh)
1249                                 continue;
1250                         ofs = bh_offset(tbh);
1251                         /* Get the mft record number. */
1252                         mft_no = (((s64)page->index << PAGE_SHIFT) + ofs)
1253                                         >> rec_size_bits;
1254                         if (mft_no < vol->mftmirr_size)
1255                                 ntfs_sync_mft_mirror(vol, mft_no,
1256                                                 (MFT_RECORD*)(kaddr + ofs),
1257                                                 sync);
1258                 }
1259                 if (!sync)
1260                         goto do_wait;
1261         }
1262         /* Remove the mst protection fixups again. */
1263         for (i = 0; i < nr_bhs; i++) {
1264                 if (!(i % bhs_per_rec)) {
1265                         tbh = bhs[i];
1266                         if (!tbh)
1267                                 continue;
1268                         post_write_mst_fixup((NTFS_RECORD*)(kaddr +
1269                                         bh_offset(tbh)));
1270                 }
1271         }
1272         flush_dcache_page(page);
1273 unm_done:
1274         /* Unlock any locked inodes. */
1275         while (nr_locked_nis-- > 0) {
1276                 ntfs_inode *tni, *base_tni;
1277                 
1278                 tni = locked_nis[nr_locked_nis];
1279                 /* Get the base inode. */
1280                 mutex_lock(&tni->extent_lock);
1281                 if (tni->nr_extents >= 0)
1282                         base_tni = tni;
1283                 else {
1284                         base_tni = tni->ext.base_ntfs_ino;
1285                         BUG_ON(!base_tni);
1286                 }
1287                 mutex_unlock(&tni->extent_lock);
1288                 ntfs_debug("Unlocking %s inode 0x%lx.",
1289                                 tni == base_tni ? "base" : "extent",
1290                                 tni->mft_no);
1291                 mutex_unlock(&tni->mrec_lock);
1292                 atomic_dec(&tni->count);
1293                 iput(VFS_I(base_tni));
1294         }
1295         SetPageUptodate(page);
1296         kunmap(page);
1297 done:
1298         if (unlikely(err && err != -ENOMEM)) {
1299                 /*
1300                  * Set page error if there is only one ntfs record in the page.
1301                  * Otherwise we would loose per-record granularity.
1302                  */
1303                 if (ni->itype.index.block_size == PAGE_SIZE)
1304                         SetPageError(page);
1305                 NVolSetErrors(vol);
1306         }
1307         if (page_is_dirty) {
1308                 ntfs_debug("Page still contains one or more dirty ntfs "
1309                                 "records.  Redirtying the page starting at "
1310                                 "record 0x%lx.", page->index <<
1311                                 (PAGE_SHIFT - rec_size_bits));
1312                 redirty_page_for_writepage(wbc, page);
1313                 unlock_page(page);
1314         } else {
1315                 /*
1316                  * Keep the VM happy.  This must be done otherwise the
1317                  * radix-tree tag PAGECACHE_TAG_DIRTY remains set even though
1318                  * the page is clean.
1319                  */
1320                 BUG_ON(PageWriteback(page));
1321                 set_page_writeback(page);
1322                 unlock_page(page);
1323                 end_page_writeback(page);
1324         }
1325         if (likely(!err))
1326                 ntfs_debug("Done.");
1327         return err;
1328 }
1329 
1330 /**
1331  * ntfs_writepage - write a @page to the backing store
1332  * @page:       page cache page to write out
1333  * @wbc:        writeback control structure
1334  *
1335  * This is called from the VM when it wants to have a dirty ntfs page cache
1336  * page cleaned.  The VM has already locked the page and marked it clean.
1337  *
1338  * For non-resident attributes, ntfs_writepage() writes the @page by calling
1339  * the ntfs version of the generic block_write_full_page() function,
1340  * ntfs_write_block(), which in turn if necessary creates and writes the
1341  * buffers associated with the page asynchronously.
1342  *
1343  * For resident attributes, OTOH, ntfs_writepage() writes the @page by copying
1344  * the data to the mft record (which at this stage is most likely in memory).
1345  * The mft record is then marked dirty and written out asynchronously via the
1346  * vfs inode dirty code path for the inode the mft record belongs to or via the
1347  * vm page dirty code path for the page the mft record is in.
1348  *
1349  * Based on ntfs_readpage() and fs/buffer.c::block_write_full_page().
1350  *
1351  * Return 0 on success and -errno on error.
1352  */
1353 static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
1354 {
1355         loff_t i_size;
1356         struct inode *vi = page->mapping->host;
1357         ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
1358         char *addr;
1359         ntfs_attr_search_ctx *ctx = NULL;
1360         MFT_RECORD *m = NULL;
1361         u32 attr_len;
1362         int err;
1363 
1364 retry_writepage:
1365         BUG_ON(!PageLocked(page));
1366         i_size = i_size_read(vi);
1367         /* Is the page fully outside i_size? (truncate in progress) */
1368         if (unlikely(page->index >= (i_size + PAGE_SIZE - 1) >>
1369                         PAGE_SHIFT)) {
1370                 /*
1371                  * The page may have dirty, unmapped buffers.  Make them
1372                  * freeable here, so the page does not leak.
1373                  */
1374                 block_invalidatepage(page, 0, PAGE_SIZE);
1375                 unlock_page(page);
1376                 ntfs_debug("Write outside i_size - truncated?");
1377                 return 0;
1378         }
1379         /*
1380          * Only $DATA attributes can be encrypted and only unnamed $DATA
1381          * attributes can be compressed.  Index root can have the flags set but
1382          * this means to create compressed/encrypted files, not that the
1383          * attribute is compressed/encrypted.  Note we need to check for
1384          * AT_INDEX_ALLOCATION since this is the type of both directory and
1385          * index inodes.
1386          */
1387         if (ni->type != AT_INDEX_ALLOCATION) {
1388                 /* If file is encrypted, deny access, just like NT4. */
1389                 if (NInoEncrypted(ni)) {
1390                         unlock_page(page);
1391                         BUG_ON(ni->type != AT_DATA);
1392                         ntfs_debug("Denying write access to encrypted file.");
1393                         return -EACCES;
1394                 }
1395                 /* Compressed data streams are handled in compress.c. */
1396                 if (NInoNonResident(ni) && NInoCompressed(ni)) {
1397                         BUG_ON(ni->type != AT_DATA);
1398                         BUG_ON(ni->name_len);
1399                         // TODO: Implement and replace this with
1400                         // return ntfs_write_compressed_block(page);
1401                         unlock_page(page);
1402                         ntfs_error(vi->i_sb, "Writing to compressed files is "
1403                                         "not supported yet.  Sorry.");
1404                         return -EOPNOTSUPP;
1405                 }
1406                 // TODO: Implement and remove this check.
1407                 if (NInoNonResident(ni) && NInoSparse(ni)) {
1408                         unlock_page(page);
1409                         ntfs_error(vi->i_sb, "Writing to sparse files is not "
1410                                         "supported yet.  Sorry.");
1411                         return -EOPNOTSUPP;
1412                 }
1413         }
1414         /* NInoNonResident() == NInoIndexAllocPresent() */
1415         if (NInoNonResident(ni)) {
1416                 /* We have to zero every time due to mmap-at-end-of-file. */
1417                 if (page->index >= (i_size >> PAGE_SHIFT)) {
1418                         /* The page straddles i_size. */
1419                         unsigned int ofs = i_size & ~PAGE_MASK;
1420                         zero_user_segment(page, ofs, PAGE_SIZE);
1421                 }
1422                 /* Handle mst protected attributes. */
1423                 if (NInoMstProtected(ni))
1424                         return ntfs_write_mst_block(page, wbc);
1425                 /* Normal, non-resident data stream. */
1426                 return ntfs_write_block(page, wbc);
1427         }
1428         /*
1429          * Attribute is resident, implying it is not compressed, encrypted, or
1430          * mst protected.  This also means the attribute is smaller than an mft
1431          * record and hence smaller than a page, so can simply return error on
1432          * any pages with index above 0.  Note the attribute can actually be
1433          * marked compressed but if it is resident the actual data is not
1434          * compressed so we are ok to ignore the compressed flag here.
1435          */
1436         BUG_ON(page_has_buffers(page));
1437         BUG_ON(!PageUptodate(page));
1438         if (unlikely(page->index > 0)) {
1439                 ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0.  "
1440                                 "Aborting write.", page->index);
1441                 BUG_ON(PageWriteback(page));
1442                 set_page_writeback(page);
1443                 unlock_page(page);
1444                 end_page_writeback(page);
1445                 return -EIO;
1446         }
1447         if (!NInoAttr(ni))
1448                 base_ni = ni;
1449         else
1450                 base_ni = ni->ext.base_ntfs_ino;
1451         /* Map, pin, and lock the mft record. */
1452         m = map_mft_record(base_ni);
1453         if (IS_ERR(m)) {
1454                 err = PTR_ERR(m);
1455                 m = NULL;
1456                 ctx = NULL;
1457                 goto err_out;
1458         }
1459         /*
1460          * If a parallel write made the attribute non-resident, drop the mft
1461          * record and retry the writepage.
1462          */
1463         if (unlikely(NInoNonResident(ni))) {
1464                 unmap_mft_record(base_ni);
1465                 goto retry_writepage;
1466         }
1467         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1468         if (unlikely(!ctx)) {
1469                 err = -ENOMEM;
1470                 goto err_out;
1471         }
1472         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1473                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1474         if (unlikely(err))
1475                 goto err_out;
1476         /*
1477          * Keep the VM happy.  This must be done otherwise the radix-tree tag
1478          * PAGECACHE_TAG_DIRTY remains set even though the page is clean.
1479          */
1480         BUG_ON(PageWriteback(page));
1481         set_page_writeback(page);
1482         unlock_page(page);
1483         attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
1484         i_size = i_size_read(vi);
1485         if (unlikely(attr_len > i_size)) {
1486                 /* Race with shrinking truncate or a failed truncate. */
1487                 attr_len = i_size;
1488                 /*
1489                  * If the truncate failed, fix it up now.  If a concurrent
1490                  * truncate, we do its job, so it does not have to do anything.
1491                  */
1492                 err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr,
1493                                 attr_len);
1494                 /* Shrinking cannot fail. */
1495                 BUG_ON(err);
1496         }
1497         addr = kmap_atomic(page);
1498         /* Copy the data from the page to the mft record. */
1499         memcpy((u8*)ctx->attr +
1500                         le16_to_cpu(ctx->attr->data.resident.value_offset),
1501                         addr, attr_len);
1502         /* Zero out of bounds area in the page cache page. */
1503         memset(addr + attr_len, 0, PAGE_SIZE - attr_len);
1504         kunmap_atomic(addr);
1505         flush_dcache_page(page);
1506         flush_dcache_mft_record_page(ctx->ntfs_ino);
1507         /* We are done with the page. */
1508         end_page_writeback(page);
1509         /* Finally, mark the mft record dirty, so it gets written back. */
1510         mark_mft_record_dirty(ctx->ntfs_ino);
1511         ntfs_attr_put_search_ctx(ctx);
1512         unmap_mft_record(base_ni);
1513         return 0;
1514 err_out:
1515         if (err == -ENOMEM) {
1516                 ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying "
1517                                 "page so we try again later.");
1518                 /*
1519                  * Put the page back on mapping->dirty_pages, but leave its
1520                  * buffers' dirty state as-is.
1521                  */
1522                 redirty_page_for_writepage(wbc, page);
1523                 err = 0;
1524         } else {
1525                 ntfs_error(vi->i_sb, "Resident attribute write failed with "
1526                                 "error %i.", err);
1527                 SetPageError(page);
1528                 NVolSetErrors(ni->vol);
1529         }
1530         unlock_page(page);
1531         if (ctx)
1532                 ntfs_attr_put_search_ctx(ctx);
1533         if (m)
1534                 unmap_mft_record(base_ni);
1535         return err;
1536 }
1537 
1538 #endif  /* NTFS_RW */
1539 
1540 /**
1541  * ntfs_bmap - map logical file block to physical device block
1542  * @mapping:    address space mapping to which the block to be mapped belongs
1543  * @block:      logical block to map to its physical device block
1544  *
1545  * For regular, non-resident files (i.e. not compressed and not encrypted), map
1546  * the logical @block belonging to the file described by the address space
1547  * mapping @mapping to its physical device block.
1548  *
1549  * The size of the block is equal to the @s_blocksize field of the super block
1550  * of the mounted file system which is guaranteed to be smaller than or equal
1551  * to the cluster size thus the block is guaranteed to fit entirely inside the
1552  * cluster which means we do not need to care how many contiguous bytes are
1553  * available after the beginning of the block.
1554  *
1555  * Return the physical device block if the mapping succeeded or 0 if the block
1556  * is sparse or there was an error.
1557  *
1558  * Note: This is a problem if someone tries to run bmap() on $Boot system file
1559  * as that really is in block zero but there is nothing we can do.  bmap() is
1560  * just broken in that respect (just like it cannot distinguish sparse from
1561  * not available or error).
1562  */
1563 static sector_t ntfs_bmap(struct address_space *mapping, sector_t block)
1564 {
1565         s64 ofs, size;
1566         loff_t i_size;
1567         LCN lcn;
1568         unsigned long blocksize, flags;
1569         ntfs_inode *ni = NTFS_I(mapping->host);
1570         ntfs_volume *vol = ni->vol;
1571         unsigned delta;
1572         unsigned char blocksize_bits, cluster_size_shift;
1573 
1574         ntfs_debug("Entering for mft_no 0x%lx, logical block 0x%llx.",
1575                         ni->mft_no, (unsigned long long)block);
1576         if (ni->type != AT_DATA || !NInoNonResident(ni) || NInoEncrypted(ni)) {
1577                 ntfs_error(vol->sb, "BMAP does not make sense for %s "
1578                                 "attributes, returning 0.",
1579                                 (ni->type != AT_DATA) ? "non-data" :
1580                                 (!NInoNonResident(ni) ? "resident" :
1581                                 "encrypted"));
1582                 return 0;
1583         }
1584         /* None of these can happen. */
1585         BUG_ON(NInoCompressed(ni));
1586         BUG_ON(NInoMstProtected(ni));
1587         blocksize = vol->sb->s_blocksize;
1588         blocksize_bits = vol->sb->s_blocksize_bits;
1589         ofs = (s64)block << blocksize_bits;
1590         read_lock_irqsave(&ni->size_lock, flags);
1591         size = ni->initialized_size;
1592         i_size = i_size_read(VFS_I(ni));
1593         read_unlock_irqrestore(&ni->size_lock, flags);
1594         /*
1595          * If the offset is outside the initialized size or the block straddles
1596          * the initialized size then pretend it is a hole unless the
1597          * initialized size equals the file size.
1598          */
1599         if (unlikely(ofs >= size || (ofs + blocksize > size && size < i_size)))
1600                 goto hole;
1601         cluster_size_shift = vol->cluster_size_bits;
1602         down_read(&ni->runlist.lock);
1603         lcn = ntfs_attr_vcn_to_lcn_nolock(ni, ofs >> cluster_size_shift, false);
1604         up_read(&ni->runlist.lock);
1605         if (unlikely(lcn < LCN_HOLE)) {
1606                 /*
1607                  * Step down to an integer to avoid gcc doing a long long
1608                  * comparision in the switch when we know @lcn is between
1609                  * LCN_HOLE and LCN_EIO (i.e. -1 to -5).
1610                  *
1611                  * Otherwise older gcc (at least on some architectures) will
1612                  * try to use __cmpdi2() which is of course not available in
1613                  * the kernel.
1614                  */
1615                 switch ((int)lcn) {
1616                 case LCN_ENOENT:
1617                         /*
1618                          * If the offset is out of bounds then pretend it is a
1619                          * hole.
1620                          */
1621                         goto hole;
1622                 case LCN_ENOMEM:
1623                         ntfs_error(vol->sb, "Not enough memory to complete "
1624                                         "mapping for inode 0x%lx.  "
1625                                         "Returning 0.", ni->mft_no);
1626                         break;
1627                 default:
1628                         ntfs_error(vol->sb, "Failed to complete mapping for "
1629                                         "inode 0x%lx.  Run chkdsk.  "
1630                                         "Returning 0.", ni->mft_no);
1631                         break;
1632                 }
1633                 return 0;
1634         }
1635         if (lcn < 0) {
1636                 /* It is a hole. */
1637 hole:
1638                 ntfs_debug("Done (returning hole).");
1639                 return 0;
1640         }
1641         /*
1642          * The block is really allocated and fullfils all our criteria.
1643          * Convert the cluster to units of block size and return the result.
1644          */
1645         delta = ofs & vol->cluster_size_mask;
1646         if (unlikely(sizeof(block) < sizeof(lcn))) {
1647                 block = lcn = ((lcn << cluster_size_shift) + delta) >>
1648                                 blocksize_bits;
1649                 /* If the block number was truncated return 0. */
1650                 if (unlikely(block != lcn)) {
1651                         ntfs_error(vol->sb, "Physical block 0x%llx is too "
1652                                         "large to be returned, returning 0.",
1653                                         (long long)lcn);
1654                         return 0;
1655                 }
1656         } else
1657                 block = ((lcn << cluster_size_shift) + delta) >>
1658                                 blocksize_bits;
1659         ntfs_debug("Done (returning block 0x%llx).", (unsigned long long)lcn);
1660         return block;
1661 }
1662 
1663 /**
1664  * ntfs_normal_aops - address space operations for normal inodes and attributes
1665  *
1666  * Note these are not used for compressed or mst protected inodes and
1667  * attributes.
1668  */
1669 const struct address_space_operations ntfs_normal_aops = {
1670         .readpage       = ntfs_readpage,
1671 #ifdef NTFS_RW
1672         .writepage      = ntfs_writepage,
1673         .set_page_dirty = __set_page_dirty_buffers,
1674 #endif /* NTFS_RW */
1675         .bmap           = ntfs_bmap,
1676         .migratepage    = buffer_migrate_page,
1677         .is_partially_uptodate = block_is_partially_uptodate,
1678         .error_remove_page = generic_error_remove_page,
1679 };
1680 
1681 /**
1682  * ntfs_compressed_aops - address space operations for compressed inodes
1683  */
1684 const struct address_space_operations ntfs_compressed_aops = {
1685         .readpage       = ntfs_readpage,
1686 #ifdef NTFS_RW
1687         .writepage      = ntfs_writepage,
1688         .set_page_dirty = __set_page_dirty_buffers,
1689 #endif /* NTFS_RW */
1690         .migratepage    = buffer_migrate_page,
1691         .is_partially_uptodate = block_is_partially_uptodate,
1692         .error_remove_page = generic_error_remove_page,
1693 };
1694 
1695 /**
1696  * ntfs_mst_aops - general address space operations for mst protecteed inodes
1697  *                 and attributes
1698  */
1699 const struct address_space_operations ntfs_mst_aops = {
1700         .readpage       = ntfs_readpage,        /* Fill page with data. */
1701 #ifdef NTFS_RW
1702         .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
1703         .set_page_dirty = __set_page_dirty_nobuffers,   /* Set the page dirty
1704                                                    without touching the buffers
1705                                                    belonging to the page. */
1706 #endif /* NTFS_RW */
1707         .migratepage    = buffer_migrate_page,
1708         .is_partially_uptodate  = block_is_partially_uptodate,
1709         .error_remove_page = generic_error_remove_page,
1710 };
1711 
1712 #ifdef NTFS_RW
1713 
1714 /**
1715  * mark_ntfs_record_dirty - mark an ntfs record dirty
1716  * @page:       page containing the ntfs record to mark dirty
1717  * @ofs:        byte offset within @page at which the ntfs record begins
1718  *
1719  * Set the buffers and the page in which the ntfs record is located dirty.
1720  *
1721  * The latter also marks the vfs inode the ntfs record belongs to dirty
1722  * (I_DIRTY_PAGES only).
1723  *
1724  * If the page does not have buffers, we create them and set them uptodate.
1725  * The page may not be locked which is why we need to handle the buffers under
1726  * the mapping->private_lock.  Once the buffers are marked dirty we no longer
1727  * need the lock since try_to_free_buffers() does not free dirty buffers.
1728  */
1729 void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
1730         struct address_space *mapping = page->mapping;
1731         ntfs_inode *ni = NTFS_I(mapping->host);
1732         struct buffer_head *bh, *head, *buffers_to_free = NULL;
1733         unsigned int end, bh_size, bh_ofs;
1734 
1735         BUG_ON(!PageUptodate(page));
1736         end = ofs + ni->itype.index.block_size;
1737         bh_size = VFS_I(ni)->i_sb->s_blocksize;
1738         spin_lock(&mapping->private_lock);
1739         if (unlikely(!page_has_buffers(page))) {
1740                 spin_unlock(&mapping->private_lock);
1741                 bh = head = alloc_page_buffers(page, bh_size, true);
1742                 spin_lock(&mapping->private_lock);
1743                 if (likely(!page_has_buffers(page))) {
1744                         struct buffer_head *tail;
1745 
1746                         do {
1747                                 set_buffer_uptodate(bh);
1748                                 tail = bh;
1749                                 bh = bh->b_this_page;
1750                         } while (bh);
1751                         tail->b_this_page = head;
1752                         attach_page_buffers(page, head);
1753                 } else
1754                         buffers_to_free = bh;
1755         }
1756         bh = head = page_buffers(page);
1757         BUG_ON(!bh);
1758         do {
1759                 bh_ofs = bh_offset(bh);
1760                 if (bh_ofs + bh_size <= ofs)
1761                         continue;
1762                 if (unlikely(bh_ofs >= end))
1763                         break;
1764                 set_buffer_dirty(bh);
1765         } while ((bh = bh->b_this_page) != head);
1766         spin_unlock(&mapping->private_lock);
1767         __set_page_dirty_nobuffers(page);
1768         if (unlikely(buffers_to_free)) {
1769                 do {
1770                         bh = buffers_to_free->b_this_page;
1771                         free_buffer_head(buffers_to_free);
1772                         buffers_to_free = bh;
1773                 } while (buffers_to_free);
1774         }
1775 }
1776 
1777 #endif /* NTFS_RW */
1778 

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