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

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  1 /*
  2  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
  3  *
  4  * Copyright (c) 2001-2011 Anton Altaparmakov and Tuxera Inc.
  5  *
  6  * This program/include file is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License as published
  8  * by the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program/include file is distributed in the hope that it will be
 12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program (in the main directory of the Linux-NTFS
 18  * distribution in the file COPYING); if not, write to the Free Software
 19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 20  */
 21 
 22 #include <linux/buffer_head.h>
 23 #include <linux/gfp.h>
 24 #include <linux/pagemap.h>
 25 #include <linux/pagevec.h>
 26 #include <linux/sched.h>
 27 #include <linux/swap.h>
 28 #include <linux/uio.h>
 29 #include <linux/writeback.h>
 30 #include <linux/aio.h>
 31 
 32 #include <asm/page.h>
 33 #include <asm/uaccess.h>
 34 
 35 #include "attrib.h"
 36 #include "bitmap.h"
 37 #include "inode.h"
 38 #include "debug.h"
 39 #include "lcnalloc.h"
 40 #include "malloc.h"
 41 #include "mft.h"
 42 #include "ntfs.h"
 43 
 44 /**
 45  * ntfs_file_open - called when an inode is about to be opened
 46  * @vi:         inode to be opened
 47  * @filp:       file structure describing the inode
 48  *
 49  * Limit file size to the page cache limit on architectures where unsigned long
 50  * is 32-bits. This is the most we can do for now without overflowing the page
 51  * cache page index. Doing it this way means we don't run into problems because
 52  * of existing too large files. It would be better to allow the user to read
 53  * the beginning of the file but I doubt very much anyone is going to hit this
 54  * check on a 32-bit architecture, so there is no point in adding the extra
 55  * complexity required to support this.
 56  *
 57  * On 64-bit architectures, the check is hopefully optimized away by the
 58  * compiler.
 59  *
 60  * After the check passes, just call generic_file_open() to do its work.
 61  */
 62 static int ntfs_file_open(struct inode *vi, struct file *filp)
 63 {
 64         if (sizeof(unsigned long) < 8) {
 65                 if (i_size_read(vi) > MAX_LFS_FILESIZE)
 66                         return -EOVERFLOW;
 67         }
 68         return generic_file_open(vi, filp);
 69 }
 70 
 71 #ifdef NTFS_RW
 72 
 73 /**
 74  * ntfs_attr_extend_initialized - extend the initialized size of an attribute
 75  * @ni:                 ntfs inode of the attribute to extend
 76  * @new_init_size:      requested new initialized size in bytes
 77  * @cached_page:        store any allocated but unused page here
 78  * @lru_pvec:           lru-buffering pagevec of the caller
 79  *
 80  * Extend the initialized size of an attribute described by the ntfs inode @ni
 81  * to @new_init_size bytes.  This involves zeroing any non-sparse space between
 82  * the old initialized size and @new_init_size both in the page cache and on
 83  * disk (if relevant complete pages are already uptodate in the page cache then
 84  * these are simply marked dirty).
 85  *
 86  * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
 87  * in the resident attribute case, it is tied to the initialized size and, in
 88  * the non-resident attribute case, it may not fall below the initialized size.
 89  *
 90  * Note that if the attribute is resident, we do not need to touch the page
 91  * cache at all.  This is because if the page cache page is not uptodate we
 92  * bring it uptodate later, when doing the write to the mft record since we
 93  * then already have the page mapped.  And if the page is uptodate, the
 94  * non-initialized region will already have been zeroed when the page was
 95  * brought uptodate and the region may in fact already have been overwritten
 96  * with new data via mmap() based writes, so we cannot just zero it.  And since
 97  * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
 98  * is unspecified, we choose not to do zeroing and thus we do not need to touch
 99  * the page at all.  For a more detailed explanation see ntfs_truncate() in
100  * fs/ntfs/inode.c.
101  *
102  * Return 0 on success and -errno on error.  In the case that an error is
103  * encountered it is possible that the initialized size will already have been
104  * incremented some way towards @new_init_size but it is guaranteed that if
105  * this is the case, the necessary zeroing will also have happened and that all
106  * metadata is self-consistent.
107  *
108  * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
109  *          held by the caller.
110  */
111 static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size)
112 {
113         s64 old_init_size;
114         loff_t old_i_size;
115         pgoff_t index, end_index;
116         unsigned long flags;
117         struct inode *vi = VFS_I(ni);
118         ntfs_inode *base_ni;
119         MFT_RECORD *m = NULL;
120         ATTR_RECORD *a;
121         ntfs_attr_search_ctx *ctx = NULL;
122         struct address_space *mapping;
123         struct page *page = NULL;
124         u8 *kattr;
125         int err;
126         u32 attr_len;
127 
128         read_lock_irqsave(&ni->size_lock, flags);
129         old_init_size = ni->initialized_size;
130         old_i_size = i_size_read(vi);
131         BUG_ON(new_init_size > ni->allocated_size);
132         read_unlock_irqrestore(&ni->size_lock, flags);
133         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
134                         "old_initialized_size 0x%llx, "
135                         "new_initialized_size 0x%llx, i_size 0x%llx.",
136                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
137                         (unsigned long long)old_init_size,
138                         (unsigned long long)new_init_size, old_i_size);
139         if (!NInoAttr(ni))
140                 base_ni = ni;
141         else
142                 base_ni = ni->ext.base_ntfs_ino;
143         /* Use goto to reduce indentation and we need the label below anyway. */
144         if (NInoNonResident(ni))
145                 goto do_non_resident_extend;
146         BUG_ON(old_init_size != old_i_size);
147         m = map_mft_record(base_ni);
148         if (IS_ERR(m)) {
149                 err = PTR_ERR(m);
150                 m = NULL;
151                 goto err_out;
152         }
153         ctx = ntfs_attr_get_search_ctx(base_ni, m);
154         if (unlikely(!ctx)) {
155                 err = -ENOMEM;
156                 goto err_out;
157         }
158         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
159                         CASE_SENSITIVE, 0, NULL, 0, ctx);
160         if (unlikely(err)) {
161                 if (err == -ENOENT)
162                         err = -EIO;
163                 goto err_out;
164         }
165         m = ctx->mrec;
166         a = ctx->attr;
167         BUG_ON(a->non_resident);
168         /* The total length of the attribute value. */
169         attr_len = le32_to_cpu(a->data.resident.value_length);
170         BUG_ON(old_i_size != (loff_t)attr_len);
171         /*
172          * Do the zeroing in the mft record and update the attribute size in
173          * the mft record.
174          */
175         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
176         memset(kattr + attr_len, 0, new_init_size - attr_len);
177         a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
178         /* Finally, update the sizes in the vfs and ntfs inodes. */
179         write_lock_irqsave(&ni->size_lock, flags);
180         i_size_write(vi, new_init_size);
181         ni->initialized_size = new_init_size;
182         write_unlock_irqrestore(&ni->size_lock, flags);
183         goto done;
184 do_non_resident_extend:
185         /*
186          * If the new initialized size @new_init_size exceeds the current file
187          * size (vfs inode->i_size), we need to extend the file size to the
188          * new initialized size.
189          */
190         if (new_init_size > old_i_size) {
191                 m = map_mft_record(base_ni);
192                 if (IS_ERR(m)) {
193                         err = PTR_ERR(m);
194                         m = NULL;
195                         goto err_out;
196                 }
197                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
198                 if (unlikely(!ctx)) {
199                         err = -ENOMEM;
200                         goto err_out;
201                 }
202                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
203                                 CASE_SENSITIVE, 0, NULL, 0, ctx);
204                 if (unlikely(err)) {
205                         if (err == -ENOENT)
206                                 err = -EIO;
207                         goto err_out;
208                 }
209                 m = ctx->mrec;
210                 a = ctx->attr;
211                 BUG_ON(!a->non_resident);
212                 BUG_ON(old_i_size != (loff_t)
213                                 sle64_to_cpu(a->data.non_resident.data_size));
214                 a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
215                 flush_dcache_mft_record_page(ctx->ntfs_ino);
216                 mark_mft_record_dirty(ctx->ntfs_ino);
217                 /* Update the file size in the vfs inode. */
218                 i_size_write(vi, new_init_size);
219                 ntfs_attr_put_search_ctx(ctx);
220                 ctx = NULL;
221                 unmap_mft_record(base_ni);
222                 m = NULL;
223         }
224         mapping = vi->i_mapping;
225         index = old_init_size >> PAGE_CACHE_SHIFT;
226         end_index = (new_init_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
227         do {
228                 /*
229                  * Read the page.  If the page is not present, this will zero
230                  * the uninitialized regions for us.
231                  */
232                 page = read_mapping_page(mapping, index, NULL);
233                 if (IS_ERR(page)) {
234                         err = PTR_ERR(page);
235                         goto init_err_out;
236                 }
237                 if (unlikely(PageError(page))) {
238                         page_cache_release(page);
239                         err = -EIO;
240                         goto init_err_out;
241                 }
242                 /*
243                  * Update the initialized size in the ntfs inode.  This is
244                  * enough to make ntfs_writepage() work.
245                  */
246                 write_lock_irqsave(&ni->size_lock, flags);
247                 ni->initialized_size = (s64)(index + 1) << PAGE_CACHE_SHIFT;
248                 if (ni->initialized_size > new_init_size)
249                         ni->initialized_size = new_init_size;
250                 write_unlock_irqrestore(&ni->size_lock, flags);
251                 /* Set the page dirty so it gets written out. */
252                 set_page_dirty(page);
253                 page_cache_release(page);
254                 /*
255                  * Play nice with the vm and the rest of the system.  This is
256                  * very much needed as we can potentially be modifying the
257                  * initialised size from a very small value to a really huge
258                  * value, e.g.
259                  *      f = open(somefile, O_TRUNC);
260                  *      truncate(f, 10GiB);
261                  *      seek(f, 10GiB);
262                  *      write(f, 1);
263                  * And this would mean we would be marking dirty hundreds of
264                  * thousands of pages or as in the above example more than
265                  * two and a half million pages!
266                  *
267                  * TODO: For sparse pages could optimize this workload by using
268                  * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
269                  * would be set in readpage for sparse pages and here we would
270                  * not need to mark dirty any pages which have this bit set.
271                  * The only caveat is that we have to clear the bit everywhere
272                  * where we allocate any clusters that lie in the page or that
273                  * contain the page.
274                  *
275                  * TODO: An even greater optimization would be for us to only
276                  * call readpage() on pages which are not in sparse regions as
277                  * determined from the runlist.  This would greatly reduce the
278                  * number of pages we read and make dirty in the case of sparse
279                  * files.
280                  */
281                 balance_dirty_pages_ratelimited(mapping);
282                 cond_resched();
283         } while (++index < end_index);
284         read_lock_irqsave(&ni->size_lock, flags);
285         BUG_ON(ni->initialized_size != new_init_size);
286         read_unlock_irqrestore(&ni->size_lock, flags);
287         /* Now bring in sync the initialized_size in the mft record. */
288         m = map_mft_record(base_ni);
289         if (IS_ERR(m)) {
290                 err = PTR_ERR(m);
291                 m = NULL;
292                 goto init_err_out;
293         }
294         ctx = ntfs_attr_get_search_ctx(base_ni, m);
295         if (unlikely(!ctx)) {
296                 err = -ENOMEM;
297                 goto init_err_out;
298         }
299         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
300                         CASE_SENSITIVE, 0, NULL, 0, ctx);
301         if (unlikely(err)) {
302                 if (err == -ENOENT)
303                         err = -EIO;
304                 goto init_err_out;
305         }
306         m = ctx->mrec;
307         a = ctx->attr;
308         BUG_ON(!a->non_resident);
309         a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
310 done:
311         flush_dcache_mft_record_page(ctx->ntfs_ino);
312         mark_mft_record_dirty(ctx->ntfs_ino);
313         if (ctx)
314                 ntfs_attr_put_search_ctx(ctx);
315         if (m)
316                 unmap_mft_record(base_ni);
317         ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
318                         (unsigned long long)new_init_size, i_size_read(vi));
319         return 0;
320 init_err_out:
321         write_lock_irqsave(&ni->size_lock, flags);
322         ni->initialized_size = old_init_size;
323         write_unlock_irqrestore(&ni->size_lock, flags);
324 err_out:
325         if (ctx)
326                 ntfs_attr_put_search_ctx(ctx);
327         if (m)
328                 unmap_mft_record(base_ni);
329         ntfs_debug("Failed.  Returning error code %i.", err);
330         return err;
331 }
332 
333 /**
334  * ntfs_fault_in_pages_readable -
335  *
336  * Fault a number of userspace pages into pagetables.
337  *
338  * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
339  * with more than two userspace pages as well as handling the single page case
340  * elegantly.
341  *
342  * If you find this difficult to understand, then think of the while loop being
343  * the following code, except that we do without the integer variable ret:
344  *
345  *      do {
346  *              ret = __get_user(c, uaddr);
347  *              uaddr += PAGE_SIZE;
348  *      } while (!ret && uaddr < end);
349  *
350  * Note, the final __get_user() may well run out-of-bounds of the user buffer,
351  * but _not_ out-of-bounds of the page the user buffer belongs to, and since
352  * this is only a read and not a write, and since it is still in the same page,
353  * it should not matter and this makes the code much simpler.
354  */
355 static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
356                 int bytes)
357 {
358         const char __user *end;
359         volatile char c;
360 
361         /* Set @end to the first byte outside the last page we care about. */
362         end = (const char __user*)PAGE_ALIGN((unsigned long)uaddr + bytes);
363 
364         while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
365                 ;
366 }
367 
368 /**
369  * ntfs_fault_in_pages_readable_iovec -
370  *
371  * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
372  */
373 static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
374                 size_t iov_ofs, int bytes)
375 {
376         do {
377                 const char __user *buf;
378                 unsigned len;
379 
380                 buf = iov->iov_base + iov_ofs;
381                 len = iov->iov_len - iov_ofs;
382                 if (len > bytes)
383                         len = bytes;
384                 ntfs_fault_in_pages_readable(buf, len);
385                 bytes -= len;
386                 iov++;
387                 iov_ofs = 0;
388         } while (bytes);
389 }
390 
391 /**
392  * __ntfs_grab_cache_pages - obtain a number of locked pages
393  * @mapping:    address space mapping from which to obtain page cache pages
394  * @index:      starting index in @mapping at which to begin obtaining pages
395  * @nr_pages:   number of page cache pages to obtain
396  * @pages:      array of pages in which to return the obtained page cache pages
397  * @cached_page: allocated but as yet unused page
398  * @lru_pvec:   lru-buffering pagevec of caller
399  *
400  * Obtain @nr_pages locked page cache pages from the mapping @mapping and
401  * starting at index @index.
402  *
403  * If a page is newly created, add it to lru list
404  *
405  * Note, the page locks are obtained in ascending page index order.
406  */
407 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
408                 pgoff_t index, const unsigned nr_pages, struct page **pages,
409                 struct page **cached_page)
410 {
411         int err, nr;
412 
413         BUG_ON(!nr_pages);
414         err = nr = 0;
415         do {
416                 pages[nr] = find_lock_page(mapping, index);
417                 if (!pages[nr]) {
418                         if (!*cached_page) {
419                                 *cached_page = page_cache_alloc(mapping);
420                                 if (unlikely(!*cached_page)) {
421                                         err = -ENOMEM;
422                                         goto err_out;
423                                 }
424                         }
425                         err = add_to_page_cache_lru(*cached_page, mapping, index,
426                                         GFP_KERNEL);
427                         if (unlikely(err)) {
428                                 if (err == -EEXIST)
429                                         continue;
430                                 goto err_out;
431                         }
432                         pages[nr] = *cached_page;
433                         *cached_page = NULL;
434                 }
435                 index++;
436                 nr++;
437         } while (nr < nr_pages);
438 out:
439         return err;
440 err_out:
441         while (nr > 0) {
442                 unlock_page(pages[--nr]);
443                 page_cache_release(pages[nr]);
444         }
445         goto out;
446 }
447 
448 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
449 {
450         lock_buffer(bh);
451         get_bh(bh);
452         bh->b_end_io = end_buffer_read_sync;
453         return submit_bh(READ, bh);
454 }
455 
456 /**
457  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
458  * @pages:      array of destination pages
459  * @nr_pages:   number of pages in @pages
460  * @pos:        byte position in file at which the write begins
461  * @bytes:      number of bytes to be written
462  *
463  * This is called for non-resident attributes from ntfs_file_buffered_write()
464  * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
465  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
466  * data has not yet been copied into the @pages.
467  * 
468  * Need to fill any holes with actual clusters, allocate buffers if necessary,
469  * ensure all the buffers are mapped, and bring uptodate any buffers that are
470  * only partially being written to.
471  *
472  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
473  * greater than PAGE_CACHE_SIZE, that all pages in @pages are entirely inside
474  * the same cluster and that they are the entirety of that cluster, and that
475  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
476  *
477  * i_size is not to be modified yet.
478  *
479  * Return 0 on success or -errno on error.
480  */
481 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
482                 unsigned nr_pages, s64 pos, size_t bytes)
483 {
484         VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
485         LCN lcn;
486         s64 bh_pos, vcn_len, end, initialized_size;
487         sector_t lcn_block;
488         struct page *page;
489         struct inode *vi;
490         ntfs_inode *ni, *base_ni = NULL;
491         ntfs_volume *vol;
492         runlist_element *rl, *rl2;
493         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
494         ntfs_attr_search_ctx *ctx = NULL;
495         MFT_RECORD *m = NULL;
496         ATTR_RECORD *a = NULL;
497         unsigned long flags;
498         u32 attr_rec_len = 0;
499         unsigned blocksize, u;
500         int err, mp_size;
501         bool rl_write_locked, was_hole, is_retry;
502         unsigned char blocksize_bits;
503         struct {
504                 u8 runlist_merged:1;
505                 u8 mft_attr_mapped:1;
506                 u8 mp_rebuilt:1;
507                 u8 attr_switched:1;
508         } status = { 0, 0, 0, 0 };
509 
510         BUG_ON(!nr_pages);
511         BUG_ON(!pages);
512         BUG_ON(!*pages);
513         vi = pages[0]->mapping->host;
514         ni = NTFS_I(vi);
515         vol = ni->vol;
516         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
517                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
518                         vi->i_ino, ni->type, pages[0]->index, nr_pages,
519                         (long long)pos, bytes);
520         blocksize = vol->sb->s_blocksize;
521         blocksize_bits = vol->sb->s_blocksize_bits;
522         u = 0;
523         do {
524                 page = pages[u];
525                 BUG_ON(!page);
526                 /*
527                  * create_empty_buffers() will create uptodate/dirty buffers if
528                  * the page is uptodate/dirty.
529                  */
530                 if (!page_has_buffers(page)) {
531                         create_empty_buffers(page, blocksize, 0);
532                         if (unlikely(!page_has_buffers(page)))
533                                 return -ENOMEM;
534                 }
535         } while (++u < nr_pages);
536         rl_write_locked = false;
537         rl = NULL;
538         err = 0;
539         vcn = lcn = -1;
540         vcn_len = 0;
541         lcn_block = -1;
542         was_hole = false;
543         cpos = pos >> vol->cluster_size_bits;
544         end = pos + bytes;
545         cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
546         /*
547          * Loop over each page and for each page over each buffer.  Use goto to
548          * reduce indentation.
549          */
550         u = 0;
551 do_next_page:
552         page = pages[u];
553         bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
554         bh = head = page_buffers(page);
555         do {
556                 VCN cdelta;
557                 s64 bh_end;
558                 unsigned bh_cofs;
559 
560                 /* Clear buffer_new on all buffers to reinitialise state. */
561                 if (buffer_new(bh))
562                         clear_buffer_new(bh);
563                 bh_end = bh_pos + blocksize;
564                 bh_cpos = bh_pos >> vol->cluster_size_bits;
565                 bh_cofs = bh_pos & vol->cluster_size_mask;
566                 if (buffer_mapped(bh)) {
567                         /*
568                          * The buffer is already mapped.  If it is uptodate,
569                          * ignore it.
570                          */
571                         if (buffer_uptodate(bh))
572                                 continue;
573                         /*
574                          * The buffer is not uptodate.  If the page is uptodate
575                          * set the buffer uptodate and otherwise ignore it.
576                          */
577                         if (PageUptodate(page)) {
578                                 set_buffer_uptodate(bh);
579                                 continue;
580                         }
581                         /*
582                          * Neither the page nor the buffer are uptodate.  If
583                          * the buffer is only partially being written to, we
584                          * need to read it in before the write, i.e. now.
585                          */
586                         if ((bh_pos < pos && bh_end > pos) ||
587                                         (bh_pos < end && bh_end > end)) {
588                                 /*
589                                  * If the buffer is fully or partially within
590                                  * the initialized size, do an actual read.
591                                  * Otherwise, simply zero the buffer.
592                                  */
593                                 read_lock_irqsave(&ni->size_lock, flags);
594                                 initialized_size = ni->initialized_size;
595                                 read_unlock_irqrestore(&ni->size_lock, flags);
596                                 if (bh_pos < initialized_size) {
597                                         ntfs_submit_bh_for_read(bh);
598                                         *wait_bh++ = bh;
599                                 } else {
600                                         zero_user(page, bh_offset(bh),
601                                                         blocksize);
602                                         set_buffer_uptodate(bh);
603                                 }
604                         }
605                         continue;
606                 }
607                 /* Unmapped buffer.  Need to map it. */
608                 bh->b_bdev = vol->sb->s_bdev;
609                 /*
610                  * If the current buffer is in the same clusters as the map
611                  * cache, there is no need to check the runlist again.  The
612                  * map cache is made up of @vcn, which is the first cached file
613                  * cluster, @vcn_len which is the number of cached file
614                  * clusters, @lcn is the device cluster corresponding to @vcn,
615                  * and @lcn_block is the block number corresponding to @lcn.
616                  */
617                 cdelta = bh_cpos - vcn;
618                 if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
619 map_buffer_cached:
620                         BUG_ON(lcn < 0);
621                         bh->b_blocknr = lcn_block +
622                                         (cdelta << (vol->cluster_size_bits -
623                                         blocksize_bits)) +
624                                         (bh_cofs >> blocksize_bits);
625                         set_buffer_mapped(bh);
626                         /*
627                          * If the page is uptodate so is the buffer.  If the
628                          * buffer is fully outside the write, we ignore it if
629                          * it was already allocated and we mark it dirty so it
630                          * gets written out if we allocated it.  On the other
631                          * hand, if we allocated the buffer but we are not
632                          * marking it dirty we set buffer_new so we can do
633                          * error recovery.
634                          */
635                         if (PageUptodate(page)) {
636                                 if (!buffer_uptodate(bh))
637                                         set_buffer_uptodate(bh);
638                                 if (unlikely(was_hole)) {
639                                         /* We allocated the buffer. */
640                                         unmap_underlying_metadata(bh->b_bdev,
641                                                         bh->b_blocknr);
642                                         if (bh_end <= pos || bh_pos >= end)
643                                                 mark_buffer_dirty(bh);
644                                         else
645                                                 set_buffer_new(bh);
646                                 }
647                                 continue;
648                         }
649                         /* Page is _not_ uptodate. */
650                         if (likely(!was_hole)) {
651                                 /*
652                                  * Buffer was already allocated.  If it is not
653                                  * uptodate and is only partially being written
654                                  * to, we need to read it in before the write,
655                                  * i.e. now.
656                                  */
657                                 if (!buffer_uptodate(bh) && bh_pos < end &&
658                                                 bh_end > pos &&
659                                                 (bh_pos < pos ||
660                                                 bh_end > end)) {
661                                         /*
662                                          * If the buffer is fully or partially
663                                          * within the initialized size, do an
664                                          * actual read.  Otherwise, simply zero
665                                          * the buffer.
666                                          */
667                                         read_lock_irqsave(&ni->size_lock,
668                                                         flags);
669                                         initialized_size = ni->initialized_size;
670                                         read_unlock_irqrestore(&ni->size_lock,
671                                                         flags);
672                                         if (bh_pos < initialized_size) {
673                                                 ntfs_submit_bh_for_read(bh);
674                                                 *wait_bh++ = bh;
675                                         } else {
676                                                 zero_user(page, bh_offset(bh),
677                                                                 blocksize);
678                                                 set_buffer_uptodate(bh);
679                                         }
680                                 }
681                                 continue;
682                         }
683                         /* We allocated the buffer. */
684                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
685                         /*
686                          * If the buffer is fully outside the write, zero it,
687                          * set it uptodate, and mark it dirty so it gets
688                          * written out.  If it is partially being written to,
689                          * zero region surrounding the write but leave it to
690                          * commit write to do anything else.  Finally, if the
691                          * buffer is fully being overwritten, do nothing.
692                          */
693                         if (bh_end <= pos || bh_pos >= end) {
694                                 if (!buffer_uptodate(bh)) {
695                                         zero_user(page, bh_offset(bh),
696                                                         blocksize);
697                                         set_buffer_uptodate(bh);
698                                 }
699                                 mark_buffer_dirty(bh);
700                                 continue;
701                         }
702                         set_buffer_new(bh);
703                         if (!buffer_uptodate(bh) &&
704                                         (bh_pos < pos || bh_end > end)) {
705                                 u8 *kaddr;
706                                 unsigned pofs;
707                                         
708                                 kaddr = kmap_atomic(page);
709                                 if (bh_pos < pos) {
710                                         pofs = bh_pos & ~PAGE_CACHE_MASK;
711                                         memset(kaddr + pofs, 0, pos - bh_pos);
712                                 }
713                                 if (bh_end > end) {
714                                         pofs = end & ~PAGE_CACHE_MASK;
715                                         memset(kaddr + pofs, 0, bh_end - end);
716                                 }
717                                 kunmap_atomic(kaddr);
718                                 flush_dcache_page(page);
719                         }
720                         continue;
721                 }
722                 /*
723                  * Slow path: this is the first buffer in the cluster.  If it
724                  * is outside allocated size and is not uptodate, zero it and
725                  * set it uptodate.
726                  */
727                 read_lock_irqsave(&ni->size_lock, flags);
728                 initialized_size = ni->allocated_size;
729                 read_unlock_irqrestore(&ni->size_lock, flags);
730                 if (bh_pos > initialized_size) {
731                         if (PageUptodate(page)) {
732                                 if (!buffer_uptodate(bh))
733                                         set_buffer_uptodate(bh);
734                         } else if (!buffer_uptodate(bh)) {
735                                 zero_user(page, bh_offset(bh), blocksize);
736                                 set_buffer_uptodate(bh);
737                         }
738                         continue;
739                 }
740                 is_retry = false;
741                 if (!rl) {
742                         down_read(&ni->runlist.lock);
743 retry_remap:
744                         rl = ni->runlist.rl;
745                 }
746                 if (likely(rl != NULL)) {
747                         /* Seek to element containing target cluster. */
748                         while (rl->length && rl[1].vcn <= bh_cpos)
749                                 rl++;
750                         lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
751                         if (likely(lcn >= 0)) {
752                                 /*
753                                  * Successful remap, setup the map cache and
754                                  * use that to deal with the buffer.
755                                  */
756                                 was_hole = false;
757                                 vcn = bh_cpos;
758                                 vcn_len = rl[1].vcn - vcn;
759                                 lcn_block = lcn << (vol->cluster_size_bits -
760                                                 blocksize_bits);
761                                 cdelta = 0;
762                                 /*
763                                  * If the number of remaining clusters touched
764                                  * by the write is smaller or equal to the
765                                  * number of cached clusters, unlock the
766                                  * runlist as the map cache will be used from
767                                  * now on.
768                                  */
769                                 if (likely(vcn + vcn_len >= cend)) {
770                                         if (rl_write_locked) {
771                                                 up_write(&ni->runlist.lock);
772                                                 rl_write_locked = false;
773                                         } else
774                                                 up_read(&ni->runlist.lock);
775                                         rl = NULL;
776                                 }
777                                 goto map_buffer_cached;
778                         }
779                 } else
780                         lcn = LCN_RL_NOT_MAPPED;
781                 /*
782                  * If it is not a hole and not out of bounds, the runlist is
783                  * probably unmapped so try to map it now.
784                  */
785                 if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
786                         if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
787                                 /* Attempt to map runlist. */
788                                 if (!rl_write_locked) {
789                                         /*
790                                          * We need the runlist locked for
791                                          * writing, so if it is locked for
792                                          * reading relock it now and retry in
793                                          * case it changed whilst we dropped
794                                          * the lock.
795                                          */
796                                         up_read(&ni->runlist.lock);
797                                         down_write(&ni->runlist.lock);
798                                         rl_write_locked = true;
799                                         goto retry_remap;
800                                 }
801                                 err = ntfs_map_runlist_nolock(ni, bh_cpos,
802                                                 NULL);
803                                 if (likely(!err)) {
804                                         is_retry = true;
805                                         goto retry_remap;
806                                 }
807                                 /*
808                                  * If @vcn is out of bounds, pretend @lcn is
809                                  * LCN_ENOENT.  As long as the buffer is out
810                                  * of bounds this will work fine.
811                                  */
812                                 if (err == -ENOENT) {
813                                         lcn = LCN_ENOENT;
814                                         err = 0;
815                                         goto rl_not_mapped_enoent;
816                                 }
817                         } else
818                                 err = -EIO;
819                         /* Failed to map the buffer, even after retrying. */
820                         bh->b_blocknr = -1;
821                         ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
822                                         "attribute type 0x%x, vcn 0x%llx, "
823                                         "vcn offset 0x%x, because its "
824                                         "location on disk could not be "
825                                         "determined%s (error code %i).",
826                                         ni->mft_no, ni->type,
827                                         (unsigned long long)bh_cpos,
828                                         (unsigned)bh_pos &
829                                         vol->cluster_size_mask,
830                                         is_retry ? " even after retrying" : "",
831                                         err);
832                         break;
833                 }
834 rl_not_mapped_enoent:
835                 /*
836                  * The buffer is in a hole or out of bounds.  We need to fill
837                  * the hole, unless the buffer is in a cluster which is not
838                  * touched by the write, in which case we just leave the buffer
839                  * unmapped.  This can only happen when the cluster size is
840                  * less than the page cache size.
841                  */
842                 if (unlikely(vol->cluster_size < PAGE_CACHE_SIZE)) {
843                         bh_cend = (bh_end + vol->cluster_size - 1) >>
844                                         vol->cluster_size_bits;
845                         if ((bh_cend <= cpos || bh_cpos >= cend)) {
846                                 bh->b_blocknr = -1;
847                                 /*
848                                  * If the buffer is uptodate we skip it.  If it
849                                  * is not but the page is uptodate, we can set
850                                  * the buffer uptodate.  If the page is not
851                                  * uptodate, we can clear the buffer and set it
852                                  * uptodate.  Whether this is worthwhile is
853                                  * debatable and this could be removed.
854                                  */
855                                 if (PageUptodate(page)) {
856                                         if (!buffer_uptodate(bh))
857                                                 set_buffer_uptodate(bh);
858                                 } else if (!buffer_uptodate(bh)) {
859                                         zero_user(page, bh_offset(bh),
860                                                 blocksize);
861                                         set_buffer_uptodate(bh);
862                                 }
863                                 continue;
864                         }
865                 }
866                 /*
867                  * Out of bounds buffer is invalid if it was not really out of
868                  * bounds.
869                  */
870                 BUG_ON(lcn != LCN_HOLE);
871                 /*
872                  * We need the runlist locked for writing, so if it is locked
873                  * for reading relock it now and retry in case it changed
874                  * whilst we dropped the lock.
875                  */
876                 BUG_ON(!rl);
877                 if (!rl_write_locked) {
878                         up_read(&ni->runlist.lock);
879                         down_write(&ni->runlist.lock);
880                         rl_write_locked = true;
881                         goto retry_remap;
882                 }
883                 /* Find the previous last allocated cluster. */
884                 BUG_ON(rl->lcn != LCN_HOLE);
885                 lcn = -1;
886                 rl2 = rl;
887                 while (--rl2 >= ni->runlist.rl) {
888                         if (rl2->lcn >= 0) {
889                                 lcn = rl2->lcn + rl2->length;
890                                 break;
891                         }
892                 }
893                 rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
894                                 false);
895                 if (IS_ERR(rl2)) {
896                         err = PTR_ERR(rl2);
897                         ntfs_debug("Failed to allocate cluster, error code %i.",
898                                         err);
899                         break;
900                 }
901                 lcn = rl2->lcn;
902                 rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
903                 if (IS_ERR(rl)) {
904                         err = PTR_ERR(rl);
905                         if (err != -ENOMEM)
906                                 err = -EIO;
907                         if (ntfs_cluster_free_from_rl(vol, rl2)) {
908                                 ntfs_error(vol->sb, "Failed to release "
909                                                 "allocated cluster in error "
910                                                 "code path.  Run chkdsk to "
911                                                 "recover the lost cluster.");
912                                 NVolSetErrors(vol);
913                         }
914                         ntfs_free(rl2);
915                         break;
916                 }
917                 ni->runlist.rl = rl;
918                 status.runlist_merged = 1;
919                 ntfs_debug("Allocated cluster, lcn 0x%llx.",
920                                 (unsigned long long)lcn);
921                 /* Map and lock the mft record and get the attribute record. */
922                 if (!NInoAttr(ni))
923                         base_ni = ni;
924                 else
925                         base_ni = ni->ext.base_ntfs_ino;
926                 m = map_mft_record(base_ni);
927                 if (IS_ERR(m)) {
928                         err = PTR_ERR(m);
929                         break;
930                 }
931                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
932                 if (unlikely(!ctx)) {
933                         err = -ENOMEM;
934                         unmap_mft_record(base_ni);
935                         break;
936                 }
937                 status.mft_attr_mapped = 1;
938                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
939                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
940                 if (unlikely(err)) {
941                         if (err == -ENOENT)
942                                 err = -EIO;
943                         break;
944                 }
945                 m = ctx->mrec;
946                 a = ctx->attr;
947                 /*
948                  * Find the runlist element with which the attribute extent
949                  * starts.  Note, we cannot use the _attr_ version because we
950                  * have mapped the mft record.  That is ok because we know the
951                  * runlist fragment must be mapped already to have ever gotten
952                  * here, so we can just use the _rl_ version.
953                  */
954                 vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
955                 rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
956                 BUG_ON(!rl2);
957                 BUG_ON(!rl2->length);
958                 BUG_ON(rl2->lcn < LCN_HOLE);
959                 highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
960                 /*
961                  * If @highest_vcn is zero, calculate the real highest_vcn
962                  * (which can really be zero).
963                  */
964                 if (!highest_vcn)
965                         highest_vcn = (sle64_to_cpu(
966                                         a->data.non_resident.allocated_size) >>
967                                         vol->cluster_size_bits) - 1;
968                 /*
969                  * Determine the size of the mapping pairs array for the new
970                  * extent, i.e. the old extent with the hole filled.
971                  */
972                 mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
973                                 highest_vcn);
974                 if (unlikely(mp_size <= 0)) {
975                         if (!(err = mp_size))
976                                 err = -EIO;
977                         ntfs_debug("Failed to get size for mapping pairs "
978                                         "array, error code %i.", err);
979                         break;
980                 }
981                 /*
982                  * Resize the attribute record to fit the new mapping pairs
983                  * array.
984                  */
985                 attr_rec_len = le32_to_cpu(a->length);
986                 err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
987                                 a->data.non_resident.mapping_pairs_offset));
988                 if (unlikely(err)) {
989                         BUG_ON(err != -ENOSPC);
990                         // TODO: Deal with this by using the current attribute
991                         // and fill it with as much of the mapping pairs
992                         // array as possible.  Then loop over each attribute
993                         // extent rewriting the mapping pairs arrays as we go
994                         // along and if when we reach the end we have not
995                         // enough space, try to resize the last attribute
996                         // extent and if even that fails, add a new attribute
997                         // extent.
998                         // We could also try to resize at each step in the hope
999                         // that we will not need to rewrite every single extent.
1000                         // Note, we may need to decompress some extents to fill
1001                         // the runlist as we are walking the extents...
1002                         ntfs_error(vol->sb, "Not enough space in the mft "
1003                                         "record for the extended attribute "
1004                                         "record.  This case is not "
1005                                         "implemented yet.");
1006                         err = -EOPNOTSUPP;
1007                         break ;
1008                 }
1009                 status.mp_rebuilt = 1;
1010                 /*
1011                  * Generate the mapping pairs array directly into the attribute
1012                  * record.
1013                  */
1014                 err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1015                                 a->data.non_resident.mapping_pairs_offset),
1016                                 mp_size, rl2, vcn, highest_vcn, NULL);
1017                 if (unlikely(err)) {
1018                         ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1019                                         "attribute type 0x%x, because building "
1020                                         "the mapping pairs failed with error "
1021                                         "code %i.", vi->i_ino,
1022                                         (unsigned)le32_to_cpu(ni->type), err);
1023                         err = -EIO;
1024                         break;
1025                 }
1026                 /* Update the highest_vcn but only if it was not set. */
1027                 if (unlikely(!a->data.non_resident.highest_vcn))
1028                         a->data.non_resident.highest_vcn =
1029                                         cpu_to_sle64(highest_vcn);
1030                 /*
1031                  * If the attribute is sparse/compressed, update the compressed
1032                  * size in the ntfs_inode structure and the attribute record.
1033                  */
1034                 if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1035                         /*
1036                          * If we are not in the first attribute extent, switch
1037                          * to it, but first ensure the changes will make it to
1038                          * disk later.
1039                          */
1040                         if (a->data.non_resident.lowest_vcn) {
1041                                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1042                                 mark_mft_record_dirty(ctx->ntfs_ino);
1043                                 ntfs_attr_reinit_search_ctx(ctx);
1044                                 err = ntfs_attr_lookup(ni->type, ni->name,
1045                                                 ni->name_len, CASE_SENSITIVE,
1046                                                 0, NULL, 0, ctx);
1047                                 if (unlikely(err)) {
1048                                         status.attr_switched = 1;
1049                                         break;
1050                                 }
1051                                 /* @m is not used any more so do not set it. */
1052                                 a = ctx->attr;
1053                         }
1054                         write_lock_irqsave(&ni->size_lock, flags);
1055                         ni->itype.compressed.size += vol->cluster_size;
1056                         a->data.non_resident.compressed_size =
1057                                         cpu_to_sle64(ni->itype.compressed.size);
1058                         write_unlock_irqrestore(&ni->size_lock, flags);
1059                 }
1060                 /* Ensure the changes make it to disk. */
1061                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1062                 mark_mft_record_dirty(ctx->ntfs_ino);
1063                 ntfs_attr_put_search_ctx(ctx);
1064                 unmap_mft_record(base_ni);
1065                 /* Successfully filled the hole. */
1066                 status.runlist_merged = 0;
1067                 status.mft_attr_mapped = 0;
1068                 status.mp_rebuilt = 0;
1069                 /* Setup the map cache and use that to deal with the buffer. */
1070                 was_hole = true;
1071                 vcn = bh_cpos;
1072                 vcn_len = 1;
1073                 lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1074                 cdelta = 0;
1075                 /*
1076                  * If the number of remaining clusters in the @pages is smaller
1077                  * or equal to the number of cached clusters, unlock the
1078                  * runlist as the map cache will be used from now on.
1079                  */
1080                 if (likely(vcn + vcn_len >= cend)) {
1081                         up_write(&ni->runlist.lock);
1082                         rl_write_locked = false;
1083                         rl = NULL;
1084                 }
1085                 goto map_buffer_cached;
1086         } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1087         /* If there are no errors, do the next page. */
1088         if (likely(!err && ++u < nr_pages))
1089                 goto do_next_page;
1090         /* If there are no errors, release the runlist lock if we took it. */
1091         if (likely(!err)) {
1092                 if (unlikely(rl_write_locked)) {
1093                         up_write(&ni->runlist.lock);
1094                         rl_write_locked = false;
1095                 } else if (unlikely(rl))
1096                         up_read(&ni->runlist.lock);
1097                 rl = NULL;
1098         }
1099         /* If we issued read requests, let them complete. */
1100         read_lock_irqsave(&ni->size_lock, flags);
1101         initialized_size = ni->initialized_size;
1102         read_unlock_irqrestore(&ni->size_lock, flags);
1103         while (wait_bh > wait) {
1104                 bh = *--wait_bh;
1105                 wait_on_buffer(bh);
1106                 if (likely(buffer_uptodate(bh))) {
1107                         page = bh->b_page;
1108                         bh_pos = ((s64)page->index << PAGE_CACHE_SHIFT) +
1109                                         bh_offset(bh);
1110                         /*
1111                          * If the buffer overflows the initialized size, need
1112                          * to zero the overflowing region.
1113                          */
1114                         if (unlikely(bh_pos + blocksize > initialized_size)) {
1115                                 int ofs = 0;
1116 
1117                                 if (likely(bh_pos < initialized_size))
1118                                         ofs = initialized_size - bh_pos;
1119                                 zero_user_segment(page, bh_offset(bh) + ofs,
1120                                                 blocksize);
1121                         }
1122                 } else /* if (unlikely(!buffer_uptodate(bh))) */
1123                         err = -EIO;
1124         }
1125         if (likely(!err)) {
1126                 /* Clear buffer_new on all buffers. */
1127                 u = 0;
1128                 do {
1129                         bh = head = page_buffers(pages[u]);
1130                         do {
1131                                 if (buffer_new(bh))
1132                                         clear_buffer_new(bh);
1133                         } while ((bh = bh->b_this_page) != head);
1134                 } while (++u < nr_pages);
1135                 ntfs_debug("Done.");
1136                 return err;
1137         }
1138         if (status.attr_switched) {
1139                 /* Get back to the attribute extent we modified. */
1140                 ntfs_attr_reinit_search_ctx(ctx);
1141                 if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1142                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1143                         ntfs_error(vol->sb, "Failed to find required "
1144                                         "attribute extent of attribute in "
1145                                         "error code path.  Run chkdsk to "
1146                                         "recover.");
1147                         write_lock_irqsave(&ni->size_lock, flags);
1148                         ni->itype.compressed.size += vol->cluster_size;
1149                         write_unlock_irqrestore(&ni->size_lock, flags);
1150                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1151                         mark_mft_record_dirty(ctx->ntfs_ino);
1152                         /*
1153                          * The only thing that is now wrong is the compressed
1154                          * size of the base attribute extent which chkdsk
1155                          * should be able to fix.
1156                          */
1157                         NVolSetErrors(vol);
1158                 } else {
1159                         m = ctx->mrec;
1160                         a = ctx->attr;
1161                         status.attr_switched = 0;
1162                 }
1163         }
1164         /*
1165          * If the runlist has been modified, need to restore it by punching a
1166          * hole into it and we then need to deallocate the on-disk cluster as
1167          * well.  Note, we only modify the runlist if we are able to generate a
1168          * new mapping pairs array, i.e. only when the mapped attribute extent
1169          * is not switched.
1170          */
1171         if (status.runlist_merged && !status.attr_switched) {
1172                 BUG_ON(!rl_write_locked);
1173                 /* Make the file cluster we allocated sparse in the runlist. */
1174                 if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1175                         ntfs_error(vol->sb, "Failed to punch hole into "
1176                                         "attribute runlist in error code "
1177                                         "path.  Run chkdsk to recover the "
1178                                         "lost cluster.");
1179                         NVolSetErrors(vol);
1180                 } else /* if (success) */ {
1181                         status.runlist_merged = 0;
1182                         /*
1183                          * Deallocate the on-disk cluster we allocated but only
1184                          * if we succeeded in punching its vcn out of the
1185                          * runlist.
1186                          */
1187                         down_write(&vol->lcnbmp_lock);
1188                         if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1189                                 ntfs_error(vol->sb, "Failed to release "
1190                                                 "allocated cluster in error "
1191                                                 "code path.  Run chkdsk to "
1192                                                 "recover the lost cluster.");
1193                                 NVolSetErrors(vol);
1194                         }
1195                         up_write(&vol->lcnbmp_lock);
1196                 }
1197         }
1198         /*
1199          * Resize the attribute record to its old size and rebuild the mapping
1200          * pairs array.  Note, we only can do this if the runlist has been
1201          * restored to its old state which also implies that the mapped
1202          * attribute extent is not switched.
1203          */
1204         if (status.mp_rebuilt && !status.runlist_merged) {
1205                 if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1206                         ntfs_error(vol->sb, "Failed to restore attribute "
1207                                         "record in error code path.  Run "
1208                                         "chkdsk to recover.");
1209                         NVolSetErrors(vol);
1210                 } else /* if (success) */ {
1211                         if (ntfs_mapping_pairs_build(vol, (u8*)a +
1212                                         le16_to_cpu(a->data.non_resident.
1213                                         mapping_pairs_offset), attr_rec_len -
1214                                         le16_to_cpu(a->data.non_resident.
1215                                         mapping_pairs_offset), ni->runlist.rl,
1216                                         vcn, highest_vcn, NULL)) {
1217                                 ntfs_error(vol->sb, "Failed to restore "
1218                                                 "mapping pairs array in error "
1219                                                 "code path.  Run chkdsk to "
1220                                                 "recover.");
1221                                 NVolSetErrors(vol);
1222                         }
1223                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1224                         mark_mft_record_dirty(ctx->ntfs_ino);
1225                 }
1226         }
1227         /* Release the mft record and the attribute. */
1228         if (status.mft_attr_mapped) {
1229                 ntfs_attr_put_search_ctx(ctx);
1230                 unmap_mft_record(base_ni);
1231         }
1232         /* Release the runlist lock. */
1233         if (rl_write_locked)
1234                 up_write(&ni->runlist.lock);
1235         else if (rl)
1236                 up_read(&ni->runlist.lock);
1237         /*
1238          * Zero out any newly allocated blocks to avoid exposing stale data.
1239          * If BH_New is set, we know that the block was newly allocated above
1240          * and that it has not been fully zeroed and marked dirty yet.
1241          */
1242         nr_pages = u;
1243         u = 0;
1244         end = bh_cpos << vol->cluster_size_bits;
1245         do {
1246                 page = pages[u];
1247                 bh = head = page_buffers(page);
1248                 do {
1249                         if (u == nr_pages &&
1250                                         ((s64)page->index << PAGE_CACHE_SHIFT) +
1251                                         bh_offset(bh) >= end)
1252                                 break;
1253                         if (!buffer_new(bh))
1254                                 continue;
1255                         clear_buffer_new(bh);
1256                         if (!buffer_uptodate(bh)) {
1257                                 if (PageUptodate(page))
1258                                         set_buffer_uptodate(bh);
1259                                 else {
1260                                         zero_user(page, bh_offset(bh),
1261                                                         blocksize);
1262                                         set_buffer_uptodate(bh);
1263                                 }
1264                         }
1265                         mark_buffer_dirty(bh);
1266                 } while ((bh = bh->b_this_page) != head);
1267         } while (++u <= nr_pages);
1268         ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1269         return err;
1270 }
1271 
1272 /*
1273  * Copy as much as we can into the pages and return the number of bytes which
1274  * were successfully copied.  If a fault is encountered then clear the pages
1275  * out to (ofs + bytes) and return the number of bytes which were copied.
1276  */
1277 static inline size_t ntfs_copy_from_user(struct page **pages,
1278                 unsigned nr_pages, unsigned ofs, const char __user *buf,
1279                 size_t bytes)
1280 {
1281         struct page **last_page = pages + nr_pages;
1282         char *addr;
1283         size_t total = 0;
1284         unsigned len;
1285         int left;
1286 
1287         do {
1288                 len = PAGE_CACHE_SIZE - ofs;
1289                 if (len > bytes)
1290                         len = bytes;
1291                 addr = kmap_atomic(*pages);
1292                 left = __copy_from_user_inatomic(addr + ofs, buf, len);
1293                 kunmap_atomic(addr);
1294                 if (unlikely(left)) {
1295                         /* Do it the slow way. */
1296                         addr = kmap(*pages);
1297                         left = __copy_from_user(addr + ofs, buf, len);
1298                         kunmap(*pages);
1299                         if (unlikely(left))
1300                                 goto err_out;
1301                 }
1302                 total += len;
1303                 bytes -= len;
1304                 if (!bytes)
1305                         break;
1306                 buf += len;
1307                 ofs = 0;
1308         } while (++pages < last_page);
1309 out:
1310         return total;
1311 err_out:
1312         total += len - left;
1313         /* Zero the rest of the target like __copy_from_user(). */
1314         while (++pages < last_page) {
1315                 bytes -= len;
1316                 if (!bytes)
1317                         break;
1318                 len = PAGE_CACHE_SIZE;
1319                 if (len > bytes)
1320                         len = bytes;
1321                 zero_user(*pages, 0, len);
1322         }
1323         goto out;
1324 }
1325 
1326 static size_t __ntfs_copy_from_user_iovec_inatomic(char *vaddr,
1327                 const struct iovec *iov, size_t iov_ofs, size_t bytes)
1328 {
1329         size_t total = 0;
1330 
1331         while (1) {
1332                 const char __user *buf = iov->iov_base + iov_ofs;
1333                 unsigned len;
1334                 size_t left;
1335 
1336                 len = iov->iov_len - iov_ofs;
1337                 if (len > bytes)
1338                         len = bytes;
1339                 left = __copy_from_user_inatomic(vaddr, buf, len);
1340                 total += len;
1341                 bytes -= len;
1342                 vaddr += len;
1343                 if (unlikely(left)) {
1344                         total -= left;
1345                         break;
1346                 }
1347                 if (!bytes)
1348                         break;
1349                 iov++;
1350                 iov_ofs = 0;
1351         }
1352         return total;
1353 }
1354 
1355 static inline void ntfs_set_next_iovec(const struct iovec **iovp,
1356                 size_t *iov_ofsp, size_t bytes)
1357 {
1358         const struct iovec *iov = *iovp;
1359         size_t iov_ofs = *iov_ofsp;
1360 
1361         while (bytes) {
1362                 unsigned len;
1363 
1364                 len = iov->iov_len - iov_ofs;
1365                 if (len > bytes)
1366                         len = bytes;
1367                 bytes -= len;
1368                 iov_ofs += len;
1369                 if (iov->iov_len == iov_ofs) {
1370                         iov++;
1371                         iov_ofs = 0;
1372                 }
1373         }
1374         *iovp = iov;
1375         *iov_ofsp = iov_ofs;
1376 }
1377 
1378 /*
1379  * This has the same side-effects and return value as ntfs_copy_from_user().
1380  * The difference is that on a fault we need to memset the remainder of the
1381  * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
1382  * single-segment behaviour.
1383  *
1384  * We call the same helper (__ntfs_copy_from_user_iovec_inatomic()) both when
1385  * atomic and when not atomic.  This is ok because it calls
1386  * __copy_from_user_inatomic() and it is ok to call this when non-atomic.  In
1387  * fact, the only difference between __copy_from_user_inatomic() and
1388  * __copy_from_user() is that the latter calls might_sleep() and the former
1389  * should not zero the tail of the buffer on error.  And on many architectures
1390  * __copy_from_user_inatomic() is just defined to __copy_from_user() so it
1391  * makes no difference at all on those architectures.
1392  */
1393 static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
1394                 unsigned nr_pages, unsigned ofs, const struct iovec **iov,
1395                 size_t *iov_ofs, size_t bytes)
1396 {
1397         struct page **last_page = pages + nr_pages;
1398         char *addr;
1399         size_t copied, len, total = 0;
1400 
1401         do {
1402                 len = PAGE_CACHE_SIZE - ofs;
1403                 if (len > bytes)
1404                         len = bytes;
1405                 addr = kmap_atomic(*pages);
1406                 copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
1407                                 *iov, *iov_ofs, len);
1408                 kunmap_atomic(addr);
1409                 if (unlikely(copied != len)) {
1410                         /* Do it the slow way. */
1411                         addr = kmap(*pages);
1412                         copied = __ntfs_copy_from_user_iovec_inatomic(addr +
1413                                         ofs, *iov, *iov_ofs, len);
1414                         if (unlikely(copied != len))
1415                                 goto err_out;
1416                         kunmap(*pages);
1417                 }
1418                 total += len;
1419                 ntfs_set_next_iovec(iov, iov_ofs, len);
1420                 bytes -= len;
1421                 if (!bytes)
1422                         break;
1423                 ofs = 0;
1424         } while (++pages < last_page);
1425 out:
1426         return total;
1427 err_out:
1428         BUG_ON(copied > len);
1429         /* Zero the rest of the target like __copy_from_user(). */
1430         memset(addr + ofs + copied, 0, len - copied);
1431         kunmap(*pages);
1432         total += copied;
1433         ntfs_set_next_iovec(iov, iov_ofs, copied);
1434         while (++pages < last_page) {
1435                 bytes -= len;
1436                 if (!bytes)
1437                         break;
1438                 len = PAGE_CACHE_SIZE;
1439                 if (len > bytes)
1440                         len = bytes;
1441                 zero_user(*pages, 0, len);
1442         }
1443         goto out;
1444 }
1445 
1446 static inline void ntfs_flush_dcache_pages(struct page **pages,
1447                 unsigned nr_pages)
1448 {
1449         BUG_ON(!nr_pages);
1450         /*
1451          * Warning: Do not do the decrement at the same time as the call to
1452          * flush_dcache_page() because it is a NULL macro on i386 and hence the
1453          * decrement never happens so the loop never terminates.
1454          */
1455         do {
1456                 --nr_pages;
1457                 flush_dcache_page(pages[nr_pages]);
1458         } while (nr_pages > 0);
1459 }
1460 
1461 /**
1462  * ntfs_commit_pages_after_non_resident_write - commit the received data
1463  * @pages:      array of destination pages
1464  * @nr_pages:   number of pages in @pages
1465  * @pos:        byte position in file at which the write begins
1466  * @bytes:      number of bytes to be written
1467  *
1468  * See description of ntfs_commit_pages_after_write(), below.
1469  */
1470 static inline int ntfs_commit_pages_after_non_resident_write(
1471                 struct page **pages, const unsigned nr_pages,
1472                 s64 pos, size_t bytes)
1473 {
1474         s64 end, initialized_size;
1475         struct inode *vi;
1476         ntfs_inode *ni, *base_ni;
1477         struct buffer_head *bh, *head;
1478         ntfs_attr_search_ctx *ctx;
1479         MFT_RECORD *m;
1480         ATTR_RECORD *a;
1481         unsigned long flags;
1482         unsigned blocksize, u;
1483         int err;
1484 
1485         vi = pages[0]->mapping->host;
1486         ni = NTFS_I(vi);
1487         blocksize = vi->i_sb->s_blocksize;
1488         end = pos + bytes;
1489         u = 0;
1490         do {
1491                 s64 bh_pos;
1492                 struct page *page;
1493                 bool partial;
1494 
1495                 page = pages[u];
1496                 bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
1497                 bh = head = page_buffers(page);
1498                 partial = false;
1499                 do {
1500                         s64 bh_end;
1501 
1502                         bh_end = bh_pos + blocksize;
1503                         if (bh_end <= pos || bh_pos >= end) {
1504                                 if (!buffer_uptodate(bh))
1505                                         partial = true;
1506                         } else {
1507                                 set_buffer_uptodate(bh);
1508                                 mark_buffer_dirty(bh);
1509                         }
1510                 } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1511                 /*
1512                  * If all buffers are now uptodate but the page is not, set the
1513                  * page uptodate.
1514                  */
1515                 if (!partial && !PageUptodate(page))
1516                         SetPageUptodate(page);
1517         } while (++u < nr_pages);
1518         /*
1519          * Finally, if we do not need to update initialized_size or i_size we
1520          * are finished.
1521          */
1522         read_lock_irqsave(&ni->size_lock, flags);
1523         initialized_size = ni->initialized_size;
1524         read_unlock_irqrestore(&ni->size_lock, flags);
1525         if (end <= initialized_size) {
1526                 ntfs_debug("Done.");
1527                 return 0;
1528         }
1529         /*
1530          * Update initialized_size/i_size as appropriate, both in the inode and
1531          * the mft record.
1532          */
1533         if (!NInoAttr(ni))
1534                 base_ni = ni;
1535         else
1536                 base_ni = ni->ext.base_ntfs_ino;
1537         /* Map, pin, and lock the mft record. */
1538         m = map_mft_record(base_ni);
1539         if (IS_ERR(m)) {
1540                 err = PTR_ERR(m);
1541                 m = NULL;
1542                 ctx = NULL;
1543                 goto err_out;
1544         }
1545         BUG_ON(!NInoNonResident(ni));
1546         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1547         if (unlikely(!ctx)) {
1548                 err = -ENOMEM;
1549                 goto err_out;
1550         }
1551         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1552                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1553         if (unlikely(err)) {
1554                 if (err == -ENOENT)
1555                         err = -EIO;
1556                 goto err_out;
1557         }
1558         a = ctx->attr;
1559         BUG_ON(!a->non_resident);
1560         write_lock_irqsave(&ni->size_lock, flags);
1561         BUG_ON(end > ni->allocated_size);
1562         ni->initialized_size = end;
1563         a->data.non_resident.initialized_size = cpu_to_sle64(end);
1564         if (end > i_size_read(vi)) {
1565                 i_size_write(vi, end);
1566                 a->data.non_resident.data_size =
1567                                 a->data.non_resident.initialized_size;
1568         }
1569         write_unlock_irqrestore(&ni->size_lock, flags);
1570         /* Mark the mft record dirty, so it gets written back. */
1571         flush_dcache_mft_record_page(ctx->ntfs_ino);
1572         mark_mft_record_dirty(ctx->ntfs_ino);
1573         ntfs_attr_put_search_ctx(ctx);
1574         unmap_mft_record(base_ni);
1575         ntfs_debug("Done.");
1576         return 0;
1577 err_out:
1578         if (ctx)
1579                 ntfs_attr_put_search_ctx(ctx);
1580         if (m)
1581                 unmap_mft_record(base_ni);
1582         ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1583                         "code %i).", err);
1584         if (err != -ENOMEM)
1585                 NVolSetErrors(ni->vol);
1586         return err;
1587 }
1588 
1589 /**
1590  * ntfs_commit_pages_after_write - commit the received data
1591  * @pages:      array of destination pages
1592  * @nr_pages:   number of pages in @pages
1593  * @pos:        byte position in file at which the write begins
1594  * @bytes:      number of bytes to be written
1595  *
1596  * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
1597  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1598  * locked but not kmap()ped.  The source data has already been copied into the
1599  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1600  * the data was copied (for non-resident attributes only) and it returned
1601  * success.
1602  *
1603  * Need to set uptodate and mark dirty all buffers within the boundary of the
1604  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1605  *
1606  * Setting the buffers dirty ensures that they get written out later when
1607  * ntfs_writepage() is invoked by the VM.
1608  *
1609  * Finally, we need to update i_size and initialized_size as appropriate both
1610  * in the inode and the mft record.
1611  *
1612  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1613  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1614  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1615  * that case, it also marks the inode dirty.
1616  *
1617  * If things have gone as outlined in
1618  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1619  * content modifications here for non-resident attributes.  For resident
1620  * attributes we need to do the uptodate bringing here which we combine with
1621  * the copying into the mft record which means we save one atomic kmap.
1622  *
1623  * Return 0 on success or -errno on error.
1624  */
1625 static int ntfs_commit_pages_after_write(struct page **pages,
1626                 const unsigned nr_pages, s64 pos, size_t bytes)
1627 {
1628         s64 end, initialized_size;
1629         loff_t i_size;
1630         struct inode *vi;
1631         ntfs_inode *ni, *base_ni;
1632         struct page *page;
1633         ntfs_attr_search_ctx *ctx;
1634         MFT_RECORD *m;
1635         ATTR_RECORD *a;
1636         char *kattr, *kaddr;
1637         unsigned long flags;
1638         u32 attr_len;
1639         int err;
1640 
1641         BUG_ON(!nr_pages);
1642         BUG_ON(!pages);
1643         page = pages[0];
1644         BUG_ON(!page);
1645         vi = page->mapping->host;
1646         ni = NTFS_I(vi);
1647         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1648                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1649                         vi->i_ino, ni->type, page->index, nr_pages,
1650                         (long long)pos, bytes);
1651         if (NInoNonResident(ni))
1652                 return ntfs_commit_pages_after_non_resident_write(pages,
1653                                 nr_pages, pos, bytes);
1654         BUG_ON(nr_pages > 1);
1655         /*
1656          * Attribute is resident, implying it is not compressed, encrypted, or
1657          * sparse.
1658          */
1659         if (!NInoAttr(ni))
1660                 base_ni = ni;
1661         else
1662                 base_ni = ni->ext.base_ntfs_ino;
1663         BUG_ON(NInoNonResident(ni));
1664         /* Map, pin, and lock the mft record. */
1665         m = map_mft_record(base_ni);
1666         if (IS_ERR(m)) {
1667                 err = PTR_ERR(m);
1668                 m = NULL;
1669                 ctx = NULL;
1670                 goto err_out;
1671         }
1672         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1673         if (unlikely(!ctx)) {
1674                 err = -ENOMEM;
1675                 goto err_out;
1676         }
1677         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1678                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1679         if (unlikely(err)) {
1680                 if (err == -ENOENT)
1681                         err = -EIO;
1682                 goto err_out;
1683         }
1684         a = ctx->attr;
1685         BUG_ON(a->non_resident);
1686         /* The total length of the attribute value. */
1687         attr_len = le32_to_cpu(a->data.resident.value_length);
1688         i_size = i_size_read(vi);
1689         BUG_ON(attr_len != i_size);
1690         BUG_ON(pos > attr_len);
1691         end = pos + bytes;
1692         BUG_ON(end > le32_to_cpu(a->length) -
1693                         le16_to_cpu(a->data.resident.value_offset));
1694         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1695         kaddr = kmap_atomic(page);
1696         /* Copy the received data from the page to the mft record. */
1697         memcpy(kattr + pos, kaddr + pos, bytes);
1698         /* Update the attribute length if necessary. */
1699         if (end > attr_len) {
1700                 attr_len = end;
1701                 a->data.resident.value_length = cpu_to_le32(attr_len);
1702         }
1703         /*
1704          * If the page is not uptodate, bring the out of bounds area(s)
1705          * uptodate by copying data from the mft record to the page.
1706          */
1707         if (!PageUptodate(page)) {
1708                 if (pos > 0)
1709                         memcpy(kaddr, kattr, pos);
1710                 if (end < attr_len)
1711                         memcpy(kaddr + end, kattr + end, attr_len - end);
1712                 /* Zero the region outside the end of the attribute value. */
1713                 memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1714                 flush_dcache_page(page);
1715                 SetPageUptodate(page);
1716         }
1717         kunmap_atomic(kaddr);
1718         /* Update initialized_size/i_size if necessary. */
1719         read_lock_irqsave(&ni->size_lock, flags);
1720         initialized_size = ni->initialized_size;
1721         BUG_ON(end > ni->allocated_size);
1722         read_unlock_irqrestore(&ni->size_lock, flags);
1723         BUG_ON(initialized_size != i_size);
1724         if (end > initialized_size) {
1725                 write_lock_irqsave(&ni->size_lock, flags);
1726                 ni->initialized_size = end;
1727                 i_size_write(vi, end);
1728                 write_unlock_irqrestore(&ni->size_lock, flags);
1729         }
1730         /* Mark the mft record dirty, so it gets written back. */
1731         flush_dcache_mft_record_page(ctx->ntfs_ino);
1732         mark_mft_record_dirty(ctx->ntfs_ino);
1733         ntfs_attr_put_search_ctx(ctx);
1734         unmap_mft_record(base_ni);
1735         ntfs_debug("Done.");
1736         return 0;
1737 err_out:
1738         if (err == -ENOMEM) {
1739                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
1740                                 "commit the write.");
1741                 if (PageUptodate(page)) {
1742                         ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1743                                         "dirty so the write will be retried "
1744                                         "later on by the VM.");
1745                         /*
1746                          * Put the page on mapping->dirty_pages, but leave its
1747                          * buffers' dirty state as-is.
1748                          */
1749                         __set_page_dirty_nobuffers(page);
1750                         err = 0;
1751                 } else
1752                         ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1753                                         "data has been lost.");
1754         } else {
1755                 ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1756                                 "with error %i.", err);
1757                 NVolSetErrors(ni->vol);
1758         }
1759         if (ctx)
1760                 ntfs_attr_put_search_ctx(ctx);
1761         if (m)
1762                 unmap_mft_record(base_ni);
1763         return err;
1764 }
1765 
1766 static void ntfs_write_failed(struct address_space *mapping, loff_t to)
1767 {
1768         struct inode *inode = mapping->host;
1769 
1770         if (to > inode->i_size) {
1771                 truncate_pagecache(inode, inode->i_size);
1772                 ntfs_truncate_vfs(inode);
1773         }
1774 }
1775 
1776 /**
1777  * ntfs_file_buffered_write -
1778  *
1779  * Locking: The vfs is holding ->i_mutex on the inode.
1780  */
1781 static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
1782                 const struct iovec *iov, unsigned long nr_segs,
1783                 loff_t pos, loff_t *ppos, size_t count)
1784 {
1785         struct file *file = iocb->ki_filp;
1786         struct address_space *mapping = file->f_mapping;
1787         struct inode *vi = mapping->host;
1788         ntfs_inode *ni = NTFS_I(vi);
1789         ntfs_volume *vol = ni->vol;
1790         struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1791         struct page *cached_page = NULL;
1792         char __user *buf = NULL;
1793         s64 end, ll;
1794         VCN last_vcn;
1795         LCN lcn;
1796         unsigned long flags;
1797         size_t bytes, iov_ofs = 0;      /* Offset in the current iovec. */
1798         ssize_t status, written;
1799         unsigned nr_pages;
1800         int err;
1801 
1802         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
1803                         "pos 0x%llx, count 0x%lx.",
1804                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
1805                         (unsigned long long)pos, (unsigned long)count);
1806         if (unlikely(!count))
1807                 return 0;
1808         BUG_ON(NInoMstProtected(ni));
1809         /*
1810          * If the attribute is not an index root and it is encrypted or
1811          * compressed, we cannot write to it yet.  Note we need to check for
1812          * AT_INDEX_ALLOCATION since this is the type of both directory and
1813          * index inodes.
1814          */
1815         if (ni->type != AT_INDEX_ALLOCATION) {
1816                 /* If file is encrypted, deny access, just like NT4. */
1817                 if (NInoEncrypted(ni)) {
1818                         /*
1819                          * Reminder for later: Encrypted files are _always_
1820                          * non-resident so that the content can always be
1821                          * encrypted.
1822                          */
1823                         ntfs_debug("Denying write access to encrypted file.");
1824                         return -EACCES;
1825                 }
1826                 if (NInoCompressed(ni)) {
1827                         /* Only unnamed $DATA attribute can be compressed. */
1828                         BUG_ON(ni->type != AT_DATA);
1829                         BUG_ON(ni->name_len);
1830                         /*
1831                          * Reminder for later: If resident, the data is not
1832                          * actually compressed.  Only on the switch to non-
1833                          * resident does compression kick in.  This is in
1834                          * contrast to encrypted files (see above).
1835                          */
1836                         ntfs_error(vi->i_sb, "Writing to compressed files is "
1837                                         "not implemented yet.  Sorry.");
1838                         return -EOPNOTSUPP;
1839                 }
1840         }
1841         /*
1842          * If a previous ntfs_truncate() failed, repeat it and abort if it
1843          * fails again.
1844          */
1845         if (unlikely(NInoTruncateFailed(ni))) {
1846                 inode_dio_wait(vi);
1847                 err = ntfs_truncate(vi);
1848                 if (err || NInoTruncateFailed(ni)) {
1849                         if (!err)
1850                                 err = -EIO;
1851                         ntfs_error(vol->sb, "Cannot perform write to inode "
1852                                         "0x%lx, attribute type 0x%x, because "
1853                                         "ntfs_truncate() failed (error code "
1854                                         "%i).", vi->i_ino,
1855                                         (unsigned)le32_to_cpu(ni->type), err);
1856                         return err;
1857                 }
1858         }
1859         /* The first byte after the write. */
1860         end = pos + count;
1861         /*
1862          * If the write goes beyond the allocated size, extend the allocation
1863          * to cover the whole of the write, rounded up to the nearest cluster.
1864          */
1865         read_lock_irqsave(&ni->size_lock, flags);
1866         ll = ni->allocated_size;
1867         read_unlock_irqrestore(&ni->size_lock, flags);
1868         if (end > ll) {
1869                 /* Extend the allocation without changing the data size. */
1870                 ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
1871                 if (likely(ll >= 0)) {
1872                         BUG_ON(pos >= ll);
1873                         /* If the extension was partial truncate the write. */
1874                         if (end > ll) {
1875                                 ntfs_debug("Truncating write to inode 0x%lx, "
1876                                                 "attribute type 0x%x, because "
1877                                                 "the allocation was only "
1878                                                 "partially extended.",
1879                                                 vi->i_ino, (unsigned)
1880                                                 le32_to_cpu(ni->type));
1881                                 end = ll;
1882                                 count = ll - pos;
1883                         }
1884                 } else {
1885                         err = ll;
1886                         read_lock_irqsave(&ni->size_lock, flags);
1887                         ll = ni->allocated_size;
1888                         read_unlock_irqrestore(&ni->size_lock, flags);
1889                         /* Perform a partial write if possible or fail. */
1890                         if (pos < ll) {
1891                                 ntfs_debug("Truncating write to inode 0x%lx, "
1892                                                 "attribute type 0x%x, because "
1893                                                 "extending the allocation "
1894                                                 "failed (error code %i).",
1895                                                 vi->i_ino, (unsigned)
1896                                                 le32_to_cpu(ni->type), err);
1897                                 end = ll;
1898                                 count = ll - pos;
1899                         } else {
1900                                 ntfs_error(vol->sb, "Cannot perform write to "
1901                                                 "inode 0x%lx, attribute type "
1902                                                 "0x%x, because extending the "
1903                                                 "allocation failed (error "
1904                                                 "code %i).", vi->i_ino,
1905                                                 (unsigned)
1906                                                 le32_to_cpu(ni->type), err);
1907                                 return err;
1908                         }
1909                 }
1910         }
1911         written = 0;
1912         /*
1913          * If the write starts beyond the initialized size, extend it up to the
1914          * beginning of the write and initialize all non-sparse space between
1915          * the old initialized size and the new one.  This automatically also
1916          * increments the vfs inode->i_size to keep it above or equal to the
1917          * initialized_size.
1918          */
1919         read_lock_irqsave(&ni->size_lock, flags);
1920         ll = ni->initialized_size;
1921         read_unlock_irqrestore(&ni->size_lock, flags);
1922         if (pos > ll) {
1923                 err = ntfs_attr_extend_initialized(ni, pos);
1924                 if (err < 0) {
1925                         ntfs_error(vol->sb, "Cannot perform write to inode "
1926                                         "0x%lx, attribute type 0x%x, because "
1927                                         "extending the initialized size "
1928                                         "failed (error code %i).", vi->i_ino,
1929                                         (unsigned)le32_to_cpu(ni->type), err);
1930                         status = err;
1931                         goto err_out;
1932                 }
1933         }
1934         /*
1935          * Determine the number of pages per cluster for non-resident
1936          * attributes.
1937          */
1938         nr_pages = 1;
1939         if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
1940                 nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
1941         /* Finally, perform the actual write. */
1942         last_vcn = -1;
1943         if (likely(nr_segs == 1))
1944                 buf = iov->iov_base;
1945         do {
1946                 VCN vcn;
1947                 pgoff_t idx, start_idx;
1948                 unsigned ofs, do_pages, u;
1949                 size_t copied;
1950 
1951                 start_idx = idx = pos >> PAGE_CACHE_SHIFT;
1952                 ofs = pos & ~PAGE_CACHE_MASK;
1953                 bytes = PAGE_CACHE_SIZE - ofs;
1954                 do_pages = 1;
1955                 if (nr_pages > 1) {
1956                         vcn = pos >> vol->cluster_size_bits;
1957                         if (vcn != last_vcn) {
1958                                 last_vcn = vcn;
1959                                 /*
1960                                  * Get the lcn of the vcn the write is in.  If
1961                                  * it is a hole, need to lock down all pages in
1962                                  * the cluster.
1963                                  */
1964                                 down_read(&ni->runlist.lock);
1965                                 lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
1966                                                 vol->cluster_size_bits, false);
1967                                 up_read(&ni->runlist.lock);
1968                                 if (unlikely(lcn < LCN_HOLE)) {
1969                                         status = -EIO;
1970                                         if (lcn == LCN_ENOMEM)
1971                                                 status = -ENOMEM;
1972                                         else
1973                                                 ntfs_error(vol->sb, "Cannot "
1974                                                         "perform write to "
1975                                                         "inode 0x%lx, "
1976                                                         "attribute type 0x%x, "
1977                                                         "because the attribute "
1978                                                         "is corrupt.",
1979                                                         vi->i_ino, (unsigned)
1980                                                         le32_to_cpu(ni->type));
1981                                         break;
1982                                 }
1983                                 if (lcn == LCN_HOLE) {
1984                                         start_idx = (pos & ~(s64)
1985                                                         vol->cluster_size_mask)
1986                                                         >> PAGE_CACHE_SHIFT;
1987                                         bytes = vol->cluster_size - (pos &
1988                                                         vol->cluster_size_mask);
1989                                         do_pages = nr_pages;
1990                                 }
1991                         }
1992                 }
1993                 if (bytes > count)
1994                         bytes = count;
1995                 /*
1996                  * Bring in the user page(s) that we will copy from _first_.
1997                  * Otherwise there is a nasty deadlock on copying from the same
1998                  * page(s) as we are writing to, without it/them being marked
1999                  * up-to-date.  Note, at present there is nothing to stop the
2000                  * pages being swapped out between us bringing them into memory
2001                  * and doing the actual copying.
2002                  */
2003                 if (likely(nr_segs == 1))
2004                         ntfs_fault_in_pages_readable(buf, bytes);
2005                 else
2006                         ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
2007                 /* Get and lock @do_pages starting at index @start_idx. */
2008                 status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
2009                                 pages, &cached_page);
2010                 if (unlikely(status))
2011                         break;
2012                 /*
2013                  * For non-resident attributes, we need to fill any holes with
2014                  * actual clusters and ensure all bufferes are mapped.  We also
2015                  * need to bring uptodate any buffers that are only partially
2016                  * being written to.
2017                  */
2018                 if (NInoNonResident(ni)) {
2019                         status = ntfs_prepare_pages_for_non_resident_write(
2020                                         pages, do_pages, pos, bytes);
2021                         if (unlikely(status)) {
2022                                 loff_t i_size;
2023 
2024                                 do {
2025                                         unlock_page(pages[--do_pages]);
2026                                         page_cache_release(pages[do_pages]);
2027                                 } while (do_pages);
2028                                 /*
2029                                  * The write preparation may have instantiated
2030                                  * allocated space outside i_size.  Trim this
2031                                  * off again.  We can ignore any errors in this
2032                                  * case as we will just be waisting a bit of
2033                                  * allocated space, which is not a disaster.
2034                                  */
2035                                 i_size = i_size_read(vi);
2036                                 if (pos + bytes > i_size) {
2037                                         ntfs_write_failed(mapping, pos + bytes);
2038                                 }
2039                                 break;
2040                         }
2041                 }
2042                 u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
2043                 if (likely(nr_segs == 1)) {
2044                         copied = ntfs_copy_from_user(pages + u, do_pages - u,
2045                                         ofs, buf, bytes);
2046                         buf += copied;
2047                 } else
2048                         copied = ntfs_copy_from_user_iovec(pages + u,
2049                                         do_pages - u, ofs, &iov, &iov_ofs,
2050                                         bytes);
2051                 ntfs_flush_dcache_pages(pages + u, do_pages - u);
2052                 status = ntfs_commit_pages_after_write(pages, do_pages, pos,
2053                                 bytes);
2054                 if (likely(!status)) {
2055                         written += copied;
2056                         count -= copied;
2057                         pos += copied;
2058                         if (unlikely(copied != bytes))
2059                                 status = -EFAULT;
2060                 }
2061                 do {
2062                         unlock_page(pages[--do_pages]);
2063                         page_cache_release(pages[do_pages]);
2064                 } while (do_pages);
2065                 if (unlikely(status))
2066                         break;
2067                 balance_dirty_pages_ratelimited(mapping);
2068                 cond_resched();
2069         } while (count);
2070 err_out:
2071         *ppos = pos;
2072         if (cached_page)
2073                 page_cache_release(cached_page);
2074         ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
2075                         written ? "written" : "status", (unsigned long)written,
2076                         (long)status);
2077         return written ? written : status;
2078 }
2079 
2080 /**
2081  * ntfs_file_aio_write_nolock -
2082  */
2083 static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
2084                 const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
2085 {
2086         struct file *file = iocb->ki_filp;
2087         struct address_space *mapping = file->f_mapping;
2088         struct inode *inode = mapping->host;
2089         loff_t pos;
2090         size_t count;           /* after file limit checks */
2091         ssize_t written, err;
2092 
2093         count = 0;
2094         err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
2095         if (err)
2096                 return err;
2097         pos = *ppos;
2098         /* We can write back this queue in page reclaim. */
2099         current->backing_dev_info = mapping->backing_dev_info;
2100         written = 0;
2101         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2102         if (err)
2103                 goto out;
2104         if (!count)
2105                 goto out;
2106         err = file_remove_suid(file);
2107         if (err)
2108                 goto out;
2109         err = file_update_time(file);
2110         if (err)
2111                 goto out;
2112         written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
2113                         count);
2114 out:
2115         current->backing_dev_info = NULL;
2116         return written ? written : err;
2117 }
2118 
2119 /**
2120  * ntfs_file_aio_write -
2121  */
2122 static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2123                 unsigned long nr_segs, loff_t pos)
2124 {
2125         struct file *file = iocb->ki_filp;
2126         struct address_space *mapping = file->f_mapping;
2127         struct inode *inode = mapping->host;
2128         ssize_t ret;
2129 
2130         BUG_ON(iocb->ki_pos != pos);
2131 
2132         mutex_lock(&inode->i_mutex);
2133         ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
2134         mutex_unlock(&inode->i_mutex);
2135         if (ret > 0) {
2136                 int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
2137                 if (err < 0)
2138                         ret = err;
2139         }
2140         return ret;
2141 }
2142 
2143 /**
2144  * ntfs_file_fsync - sync a file to disk
2145  * @filp:       file to be synced
2146  * @datasync:   if non-zero only flush user data and not metadata
2147  *
2148  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
2149  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
2150  *
2151  * If @datasync is false, write the mft record and all associated extent mft
2152  * records as well as the $DATA attribute and then sync the block device.
2153  *
2154  * If @datasync is true and the attribute is non-resident, we skip the writing
2155  * of the mft record and all associated extent mft records (this might still
2156  * happen due to the write_inode_now() call).
2157  *
2158  * Also, if @datasync is true, we do not wait on the inode to be written out
2159  * but we always wait on the page cache pages to be written out.
2160  *
2161  * Locking: Caller must hold i_mutex on the inode.
2162  *
2163  * TODO: We should probably also write all attribute/index inodes associated
2164  * with this inode but since we have no simple way of getting to them we ignore
2165  * this problem for now.
2166  */
2167 static int ntfs_file_fsync(struct file *filp, loff_t start, loff_t end,
2168                            int datasync)
2169 {
2170         struct inode *vi = filp->f_mapping->host;
2171         int err, ret = 0;
2172 
2173         ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
2174 
2175         err = filemap_write_and_wait_range(vi->i_mapping, start, end);
2176         if (err)
2177                 return err;
2178         mutex_lock(&vi->i_mutex);
2179 
2180         BUG_ON(S_ISDIR(vi->i_mode));
2181         if (!datasync || !NInoNonResident(NTFS_I(vi)))
2182                 ret = __ntfs_write_inode(vi, 1);
2183         write_inode_now(vi, !datasync);
2184         /*
2185          * NOTE: If we were to use mapping->private_list (see ext2 and
2186          * fs/buffer.c) for dirty blocks then we could optimize the below to be
2187          * sync_mapping_buffers(vi->i_mapping).
2188          */
2189         err = sync_blockdev(vi->i_sb->s_bdev);
2190         if (unlikely(err && !ret))
2191                 ret = err;
2192         if (likely(!ret))
2193                 ntfs_debug("Done.");
2194         else
2195                 ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
2196                                 "%u.", datasync ? "data" : "", vi->i_ino, -ret);
2197         mutex_unlock(&vi->i_mutex);
2198         return ret;
2199 }
2200 
2201 #endif /* NTFS_RW */
2202 
2203 const struct file_operations ntfs_file_ops = {
2204         .llseek         = generic_file_llseek,   /* Seek inside file. */
2205         .read           = do_sync_read,          /* Read from file. */
2206         .aio_read       = generic_file_aio_read, /* Async read from file. */
2207 #ifdef NTFS_RW
2208         .write          = do_sync_write,         /* Write to file. */
2209         .aio_write      = ntfs_file_aio_write,   /* Async write to file. */
2210         /*.release      = ,*/                    /* Last file is closed.  See
2211                                                     fs/ext2/file.c::
2212                                                     ext2_release_file() for
2213                                                     how to use this to discard
2214                                                     preallocated space for
2215                                                     write opened files. */
2216         .fsync          = ntfs_file_fsync,       /* Sync a file to disk. */
2217         /*.aio_fsync    = ,*/                    /* Sync all outstanding async
2218                                                     i/o operations on a
2219                                                     kiocb. */
2220 #endif /* NTFS_RW */
2221         /*.ioctl        = ,*/                    /* Perform function on the
2222                                                     mounted filesystem. */
2223         .mmap           = generic_file_mmap,     /* Mmap file. */
2224         .open           = ntfs_file_open,        /* Open file. */
2225         .splice_read    = generic_file_splice_read /* Zero-copy data send with
2226                                                     the data source being on
2227                                                     the ntfs partition.  We do
2228                                                     not need to care about the
2229                                                     data destination. */
2230         /*.sendpage     = ,*/                    /* Zero-copy data send with
2231                                                     the data destination being
2232                                                     on the ntfs partition.  We
2233                                                     do not need to care about
2234                                                     the data source. */
2235 };
2236 
2237 const struct inode_operations ntfs_file_inode_ops = {
2238 #ifdef NTFS_RW
2239         .setattr        = ntfs_setattr,
2240 #endif /* NTFS_RW */
2241 };
2242 
2243 const struct file_operations ntfs_empty_file_ops = {};
2244 
2245 const struct inode_operations ntfs_empty_inode_ops = {};
2246 

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