mm: make read_cache_page synchronous
[linux-2.6.git] / fs / ntfs / file.c
1 /*
2  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
3  *
4  * Copyright (c) 2001-2006 Anton Altaparmakov
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/pagemap.h>
24 #include <linux/pagevec.h>
25 #include <linux/sched.h>
26 #include <linux/swap.h>
27 #include <linux/uio.h>
28 #include <linux/writeback.h>
29
30 #include <asm/page.h>
31 #include <asm/uaccess.h>
32
33 #include "attrib.h"
34 #include "bitmap.h"
35 #include "inode.h"
36 #include "debug.h"
37 #include "lcnalloc.h"
38 #include "malloc.h"
39 #include "mft.h"
40 #include "ntfs.h"
41
42 /**
43  * ntfs_file_open - called when an inode is about to be opened
44  * @vi:         inode to be opened
45  * @filp:       file structure describing the inode
46  *
47  * Limit file size to the page cache limit on architectures where unsigned long
48  * is 32-bits. This is the most we can do for now without overflowing the page
49  * cache page index. Doing it this way means we don't run into problems because
50  * of existing too large files. It would be better to allow the user to read
51  * the beginning of the file but I doubt very much anyone is going to hit this
52  * check on a 32-bit architecture, so there is no point in adding the extra
53  * complexity required to support this.
54  *
55  * On 64-bit architectures, the check is hopefully optimized away by the
56  * compiler.
57  *
58  * After the check passes, just call generic_file_open() to do its work.
59  */
60 static int ntfs_file_open(struct inode *vi, struct file *filp)
61 {
62         if (sizeof(unsigned long) < 8) {
63                 if (i_size_read(vi) > MAX_LFS_FILESIZE)
64                         return -EFBIG;
65         }
66         return generic_file_open(vi, filp);
67 }
68
69 #ifdef NTFS_RW
70
71 /**
72  * ntfs_attr_extend_initialized - extend the initialized size of an attribute
73  * @ni:                 ntfs inode of the attribute to extend
74  * @new_init_size:      requested new initialized size in bytes
75  * @cached_page:        store any allocated but unused page here
76  * @lru_pvec:           lru-buffering pagevec of the caller
77  *
78  * Extend the initialized size of an attribute described by the ntfs inode @ni
79  * to @new_init_size bytes.  This involves zeroing any non-sparse space between
80  * the old initialized size and @new_init_size both in the page cache and on
81  * disk (if relevant complete pages are already uptodate in the page cache then
82  * these are simply marked dirty).
83  *
84  * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
85  * in the resident attribute case, it is tied to the initialized size and, in
86  * the non-resident attribute case, it may not fall below the initialized size.
87  *
88  * Note that if the attribute is resident, we do not need to touch the page
89  * cache at all.  This is because if the page cache page is not uptodate we
90  * bring it uptodate later, when doing the write to the mft record since we
91  * then already have the page mapped.  And if the page is uptodate, the
92  * non-initialized region will already have been zeroed when the page was
93  * brought uptodate and the region may in fact already have been overwritten
94  * with new data via mmap() based writes, so we cannot just zero it.  And since
95  * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
96  * is unspecified, we choose not to do zeroing and thus we do not need to touch
97  * the page at all.  For a more detailed explanation see ntfs_truncate() in
98  * fs/ntfs/inode.c.
99  *
100  * @cached_page and @lru_pvec are just optimizations for dealing with multiple
101  * pages.
102  *
103  * Return 0 on success and -errno on error.  In the case that an error is
104  * encountered it is possible that the initialized size will already have been
105  * incremented some way towards @new_init_size but it is guaranteed that if
106  * this is the case, the necessary zeroing will also have happened and that all
107  * metadata is self-consistent.
108  *
109  * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
110  *          held by the caller.
111  */
112 static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size,
113                 struct page **cached_page, struct pagevec *lru_pvec)
114 {
115         s64 old_init_size;
116         loff_t old_i_size;
117         pgoff_t index, end_index;
118         unsigned long flags;
119         struct inode *vi = VFS_I(ni);
120         ntfs_inode *base_ni;
121         MFT_RECORD *m = NULL;
122         ATTR_RECORD *a;
123         ntfs_attr_search_ctx *ctx = NULL;
124         struct address_space *mapping;
125         struct page *page = NULL;
126         u8 *kattr;
127         int err;
128         u32 attr_len;
129
130         read_lock_irqsave(&ni->size_lock, flags);
131         old_init_size = ni->initialized_size;
132         old_i_size = i_size_read(vi);
133         BUG_ON(new_init_size > ni->allocated_size);
134         read_unlock_irqrestore(&ni->size_lock, flags);
135         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
136                         "old_initialized_size 0x%llx, "
137                         "new_initialized_size 0x%llx, i_size 0x%llx.",
138                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
139                         (unsigned long long)old_init_size,
140                         (unsigned long long)new_init_size, old_i_size);
141         if (!NInoAttr(ni))
142                 base_ni = ni;
143         else
144                 base_ni = ni->ext.base_ntfs_ino;
145         /* Use goto to reduce indentation and we need the label below anyway. */
146         if (NInoNonResident(ni))
147                 goto do_non_resident_extend;
148         BUG_ON(old_init_size != old_i_size);
149         m = map_mft_record(base_ni);
150         if (IS_ERR(m)) {
151                 err = PTR_ERR(m);
152                 m = NULL;
153                 goto err_out;
154         }
155         ctx = ntfs_attr_get_search_ctx(base_ni, m);
156         if (unlikely(!ctx)) {
157                 err = -ENOMEM;
158                 goto err_out;
159         }
160         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
161                         CASE_SENSITIVE, 0, NULL, 0, ctx);
162         if (unlikely(err)) {
163                 if (err == -ENOENT)
164                         err = -EIO;
165                 goto err_out;
166         }
167         m = ctx->mrec;
168         a = ctx->attr;
169         BUG_ON(a->non_resident);
170         /* The total length of the attribute value. */
171         attr_len = le32_to_cpu(a->data.resident.value_length);
172         BUG_ON(old_i_size != (loff_t)attr_len);
173         /*
174          * Do the zeroing in the mft record and update the attribute size in
175          * the mft record.
176          */
177         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
178         memset(kattr + attr_len, 0, new_init_size - attr_len);
179         a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
180         /* Finally, update the sizes in the vfs and ntfs inodes. */
181         write_lock_irqsave(&ni->size_lock, flags);
182         i_size_write(vi, new_init_size);
183         ni->initialized_size = new_init_size;
184         write_unlock_irqrestore(&ni->size_lock, flags);
185         goto done;
186 do_non_resident_extend:
187         /*
188          * If the new initialized size @new_init_size exceeds the current file
189          * size (vfs inode->i_size), we need to extend the file size to the
190          * new initialized size.
191          */
192         if (new_init_size > old_i_size) {
193                 m = map_mft_record(base_ni);
194                 if (IS_ERR(m)) {
195                         err = PTR_ERR(m);
196                         m = NULL;
197                         goto err_out;
198                 }
199                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
200                 if (unlikely(!ctx)) {
201                         err = -ENOMEM;
202                         goto err_out;
203                 }
204                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
205                                 CASE_SENSITIVE, 0, NULL, 0, ctx);
206                 if (unlikely(err)) {
207                         if (err == -ENOENT)
208                                 err = -EIO;
209                         goto err_out;
210                 }
211                 m = ctx->mrec;
212                 a = ctx->attr;
213                 BUG_ON(!a->non_resident);
214                 BUG_ON(old_i_size != (loff_t)
215                                 sle64_to_cpu(a->data.non_resident.data_size));
216                 a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
217                 flush_dcache_mft_record_page(ctx->ntfs_ino);
218                 mark_mft_record_dirty(ctx->ntfs_ino);
219                 /* Update the file size in the vfs inode. */
220                 i_size_write(vi, new_init_size);
221                 ntfs_attr_put_search_ctx(ctx);
222                 ctx = NULL;
223                 unmap_mft_record(base_ni);
224                 m = NULL;
225         }
226         mapping = vi->i_mapping;
227         index = old_init_size >> PAGE_CACHE_SHIFT;
228         end_index = (new_init_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
229         do {
230                 /*
231                  * Read the page.  If the page is not present, this will zero
232                  * the uninitialized regions for us.
233                  */
234                 page = read_mapping_page(mapping, index, NULL);
235                 if (IS_ERR(page)) {
236                         err = PTR_ERR(page);
237                         goto init_err_out;
238                 }
239                 if (unlikely(PageError(page))) {
240                         page_cache_release(page);
241                         err = -EIO;
242                         goto init_err_out;
243                 }
244                 /*
245                  * Update the initialized size in the ntfs inode.  This is
246                  * enough to make ntfs_writepage() work.
247                  */
248                 write_lock_irqsave(&ni->size_lock, flags);
249                 ni->initialized_size = (s64)(index + 1) << PAGE_CACHE_SHIFT;
250                 if (ni->initialized_size > new_init_size)
251                         ni->initialized_size = new_init_size;
252                 write_unlock_irqrestore(&ni->size_lock, flags);
253                 /* Set the page dirty so it gets written out. */
254                 set_page_dirty(page);
255                 page_cache_release(page);
256                 /*
257                  * Play nice with the vm and the rest of the system.  This is
258                  * very much needed as we can potentially be modifying the
259                  * initialised size from a very small value to a really huge
260                  * value, e.g.
261                  *      f = open(somefile, O_TRUNC);
262                  *      truncate(f, 10GiB);
263                  *      seek(f, 10GiB);
264                  *      write(f, 1);
265                  * And this would mean we would be marking dirty hundreds of
266                  * thousands of pages or as in the above example more than
267                  * two and a half million pages!
268                  *
269                  * TODO: For sparse pages could optimize this workload by using
270                  * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
271                  * would be set in readpage for sparse pages and here we would
272                  * not need to mark dirty any pages which have this bit set.
273                  * The only caveat is that we have to clear the bit everywhere
274                  * where we allocate any clusters that lie in the page or that
275                  * contain the page.
276                  *
277                  * TODO: An even greater optimization would be for us to only
278                  * call readpage() on pages which are not in sparse regions as
279                  * determined from the runlist.  This would greatly reduce the
280                  * number of pages we read and make dirty in the case of sparse
281                  * files.
282                  */
283                 balance_dirty_pages_ratelimited(mapping);
284                 cond_resched();
285         } while (++index < end_index);
286         read_lock_irqsave(&ni->size_lock, flags);
287         BUG_ON(ni->initialized_size != new_init_size);
288         read_unlock_irqrestore(&ni->size_lock, flags);
289         /* Now bring in sync the initialized_size in the mft record. */
290         m = map_mft_record(base_ni);
291         if (IS_ERR(m)) {
292                 err = PTR_ERR(m);
293                 m = NULL;
294                 goto init_err_out;
295         }
296         ctx = ntfs_attr_get_search_ctx(base_ni, m);
297         if (unlikely(!ctx)) {
298                 err = -ENOMEM;
299                 goto init_err_out;
300         }
301         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
302                         CASE_SENSITIVE, 0, NULL, 0, ctx);
303         if (unlikely(err)) {
304                 if (err == -ENOENT)
305                         err = -EIO;
306                 goto init_err_out;
307         }
308         m = ctx->mrec;
309         a = ctx->attr;
310         BUG_ON(!a->non_resident);
311         a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
312 done:
313         flush_dcache_mft_record_page(ctx->ntfs_ino);
314         mark_mft_record_dirty(ctx->ntfs_ino);
315         if (ctx)
316                 ntfs_attr_put_search_ctx(ctx);
317         if (m)
318                 unmap_mft_record(base_ni);
319         ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
320                         (unsigned long long)new_init_size, i_size_read(vi));
321         return 0;
322 init_err_out:
323         write_lock_irqsave(&ni->size_lock, flags);
324         ni->initialized_size = old_init_size;
325         write_unlock_irqrestore(&ni->size_lock, flags);
326 err_out:
327         if (ctx)
328                 ntfs_attr_put_search_ctx(ctx);
329         if (m)
330                 unmap_mft_record(base_ni);
331         ntfs_debug("Failed.  Returning error code %i.", err);
332         return err;
333 }
334
335 /**
336  * ntfs_fault_in_pages_readable -
337  *
338  * Fault a number of userspace pages into pagetables.
339  *
340  * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
341  * with more than two userspace pages as well as handling the single page case
342  * elegantly.
343  *
344  * If you find this difficult to understand, then think of the while loop being
345  * the following code, except that we do without the integer variable ret:
346  *
347  *      do {
348  *              ret = __get_user(c, uaddr);
349  *              uaddr += PAGE_SIZE;
350  *      } while (!ret && uaddr < end);
351  *
352  * Note, the final __get_user() may well run out-of-bounds of the user buffer,
353  * but _not_ out-of-bounds of the page the user buffer belongs to, and since
354  * this is only a read and not a write, and since it is still in the same page,
355  * it should not matter and this makes the code much simpler.
356  */
357 static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
358                 int bytes)
359 {
360         const char __user *end;
361         volatile char c;
362
363         /* Set @end to the first byte outside the last page we care about. */
364         end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
365
366         while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
367                 ;
368 }
369
370 /**
371  * ntfs_fault_in_pages_readable_iovec -
372  *
373  * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
374  */
375 static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
376                 size_t iov_ofs, int bytes)
377 {
378         do {
379                 const char __user *buf;
380                 unsigned len;
381
382                 buf = iov->iov_base + iov_ofs;
383                 len = iov->iov_len - iov_ofs;
384                 if (len > bytes)
385                         len = bytes;
386                 ntfs_fault_in_pages_readable(buf, len);
387                 bytes -= len;
388                 iov++;
389                 iov_ofs = 0;
390         } while (bytes);
391 }
392
393 /**
394  * __ntfs_grab_cache_pages - obtain a number of locked pages
395  * @mapping:    address space mapping from which to obtain page cache pages
396  * @index:      starting index in @mapping at which to begin obtaining pages
397  * @nr_pages:   number of page cache pages to obtain
398  * @pages:      array of pages in which to return the obtained page cache pages
399  * @cached_page: allocated but as yet unused page
400  * @lru_pvec:   lru-buffering pagevec of caller
401  *
402  * Obtain @nr_pages locked page cache pages from the mapping @maping and
403  * starting at index @index.
404  *
405  * If a page is newly created, increment its refcount and add it to the
406  * caller's lru-buffering pagevec @lru_pvec.
407  *
408  * This is the same as mm/filemap.c::__grab_cache_page(), except that @nr_pages
409  * are obtained at once instead of just one page and that 0 is returned on
410  * success and -errno on error.
411  *
412  * Note, the page locks are obtained in ascending page index order.
413  */
414 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
415                 pgoff_t index, const unsigned nr_pages, struct page **pages,
416                 struct page **cached_page, struct pagevec *lru_pvec)
417 {
418         int err, nr;
419
420         BUG_ON(!nr_pages);
421         err = nr = 0;
422         do {
423                 pages[nr] = find_lock_page(mapping, index);
424                 if (!pages[nr]) {
425                         if (!*cached_page) {
426                                 *cached_page = page_cache_alloc(mapping);
427                                 if (unlikely(!*cached_page)) {
428                                         err = -ENOMEM;
429                                         goto err_out;
430                                 }
431                         }
432                         err = add_to_page_cache(*cached_page, mapping, index,
433                                         GFP_KERNEL);
434                         if (unlikely(err)) {
435                                 if (err == -EEXIST)
436                                         continue;
437                                 goto err_out;
438                         }
439                         pages[nr] = *cached_page;
440                         page_cache_get(*cached_page);
441                         if (unlikely(!pagevec_add(lru_pvec, *cached_page)))
442                                 __pagevec_lru_add(lru_pvec);
443                         *cached_page = NULL;
444                 }
445                 index++;
446                 nr++;
447         } while (nr < nr_pages);
448 out:
449         return err;
450 err_out:
451         while (nr > 0) {
452                 unlock_page(pages[--nr]);
453                 page_cache_release(pages[nr]);
454         }
455         goto out;
456 }
457
458 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
459 {
460         lock_buffer(bh);
461         get_bh(bh);
462         bh->b_end_io = end_buffer_read_sync;
463         return submit_bh(READ, bh);
464 }
465
466 /**
467  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
468  * @pages:      array of destination pages
469  * @nr_pages:   number of pages in @pages
470  * @pos:        byte position in file at which the write begins
471  * @bytes:      number of bytes to be written
472  *
473  * This is called for non-resident attributes from ntfs_file_buffered_write()
474  * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
475  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
476  * data has not yet been copied into the @pages.
477  * 
478  * Need to fill any holes with actual clusters, allocate buffers if necessary,
479  * ensure all the buffers are mapped, and bring uptodate any buffers that are
480  * only partially being written to.
481  *
482  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
483  * greater than PAGE_CACHE_SIZE, that all pages in @pages are entirely inside
484  * the same cluster and that they are the entirety of that cluster, and that
485  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
486  *
487  * i_size is not to be modified yet.
488  *
489  * Return 0 on success or -errno on error.
490  */
491 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
492                 unsigned nr_pages, s64 pos, size_t bytes)
493 {
494         VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
495         LCN lcn;
496         s64 bh_pos, vcn_len, end, initialized_size;
497         sector_t lcn_block;
498         struct page *page;
499         struct inode *vi;
500         ntfs_inode *ni, *base_ni = NULL;
501         ntfs_volume *vol;
502         runlist_element *rl, *rl2;
503         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
504         ntfs_attr_search_ctx *ctx = NULL;
505         MFT_RECORD *m = NULL;
506         ATTR_RECORD *a = NULL;
507         unsigned long flags;
508         u32 attr_rec_len = 0;
509         unsigned blocksize, u;
510         int err, mp_size;
511         bool rl_write_locked, was_hole, is_retry;
512         unsigned char blocksize_bits;
513         struct {
514                 u8 runlist_merged:1;
515                 u8 mft_attr_mapped:1;
516                 u8 mp_rebuilt:1;
517                 u8 attr_switched:1;
518         } status = { 0, 0, 0, 0 };
519
520         BUG_ON(!nr_pages);
521         BUG_ON(!pages);
522         BUG_ON(!*pages);
523         vi = pages[0]->mapping->host;
524         ni = NTFS_I(vi);
525         vol = ni->vol;
526         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
527                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
528                         vi->i_ino, ni->type, pages[0]->index, nr_pages,
529                         (long long)pos, bytes);
530         blocksize = vol->sb->s_blocksize;
531         blocksize_bits = vol->sb->s_blocksize_bits;
532         u = 0;
533         do {
534                 struct page *page = pages[u];
535                 /*
536                  * create_empty_buffers() will create uptodate/dirty buffers if
537                  * the page is uptodate/dirty.
538                  */
539                 if (!page_has_buffers(page)) {
540                         create_empty_buffers(page, blocksize, 0);
541                         if (unlikely(!page_has_buffers(page)))
542                                 return -ENOMEM;
543                 }
544         } while (++u < nr_pages);
545         rl_write_locked = false;
546         rl = NULL;
547         err = 0;
548         vcn = lcn = -1;
549         vcn_len = 0;
550         lcn_block = -1;
551         was_hole = false;
552         cpos = pos >> vol->cluster_size_bits;
553         end = pos + bytes;
554         cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
555         /*
556          * Loop over each page and for each page over each buffer.  Use goto to
557          * reduce indentation.
558          */
559         u = 0;
560 do_next_page:
561         page = pages[u];
562         bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
563         bh = head = page_buffers(page);
564         do {
565                 VCN cdelta;
566                 s64 bh_end;
567                 unsigned bh_cofs;
568
569                 /* Clear buffer_new on all buffers to reinitialise state. */
570                 if (buffer_new(bh))
571                         clear_buffer_new(bh);
572                 bh_end = bh_pos + blocksize;
573                 bh_cpos = bh_pos >> vol->cluster_size_bits;
574                 bh_cofs = bh_pos & vol->cluster_size_mask;
575                 if (buffer_mapped(bh)) {
576                         /*
577                          * The buffer is already mapped.  If it is uptodate,
578                          * ignore it.
579                          */
580                         if (buffer_uptodate(bh))
581                                 continue;
582                         /*
583                          * The buffer is not uptodate.  If the page is uptodate
584                          * set the buffer uptodate and otherwise ignore it.
585                          */
586                         if (PageUptodate(page)) {
587                                 set_buffer_uptodate(bh);
588                                 continue;
589                         }
590                         /*
591                          * Neither the page nor the buffer are uptodate.  If
592                          * the buffer is only partially being written to, we
593                          * need to read it in before the write, i.e. now.
594                          */
595                         if ((bh_pos < pos && bh_end > pos) ||
596                                         (bh_pos < end && bh_end > end)) {
597                                 /*
598                                  * If the buffer is fully or partially within
599                                  * the initialized size, do an actual read.
600                                  * Otherwise, simply zero the buffer.
601                                  */
602                                 read_lock_irqsave(&ni->size_lock, flags);
603                                 initialized_size = ni->initialized_size;
604                                 read_unlock_irqrestore(&ni->size_lock, flags);
605                                 if (bh_pos < initialized_size) {
606                                         ntfs_submit_bh_for_read(bh);
607                                         *wait_bh++ = bh;
608                                 } else {
609                                         u8 *kaddr = kmap_atomic(page, KM_USER0);
610                                         memset(kaddr + bh_offset(bh), 0,
611                                                         blocksize);
612                                         kunmap_atomic(kaddr, KM_USER0);
613                                         flush_dcache_page(page);
614                                         set_buffer_uptodate(bh);
615                                 }
616                         }
617                         continue;
618                 }
619                 /* Unmapped buffer.  Need to map it. */
620                 bh->b_bdev = vol->sb->s_bdev;
621                 /*
622                  * If the current buffer is in the same clusters as the map
623                  * cache, there is no need to check the runlist again.  The
624                  * map cache is made up of @vcn, which is the first cached file
625                  * cluster, @vcn_len which is the number of cached file
626                  * clusters, @lcn is the device cluster corresponding to @vcn,
627                  * and @lcn_block is the block number corresponding to @lcn.
628                  */
629                 cdelta = bh_cpos - vcn;
630                 if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
631 map_buffer_cached:
632                         BUG_ON(lcn < 0);
633                         bh->b_blocknr = lcn_block +
634                                         (cdelta << (vol->cluster_size_bits -
635                                         blocksize_bits)) +
636                                         (bh_cofs >> blocksize_bits);
637                         set_buffer_mapped(bh);
638                         /*
639                          * If the page is uptodate so is the buffer.  If the
640                          * buffer is fully outside the write, we ignore it if
641                          * it was already allocated and we mark it dirty so it
642                          * gets written out if we allocated it.  On the other
643                          * hand, if we allocated the buffer but we are not
644                          * marking it dirty we set buffer_new so we can do
645                          * error recovery.
646                          */
647                         if (PageUptodate(page)) {
648                                 if (!buffer_uptodate(bh))
649                                         set_buffer_uptodate(bh);
650                                 if (unlikely(was_hole)) {
651                                         /* We allocated the buffer. */
652                                         unmap_underlying_metadata(bh->b_bdev,
653                                                         bh->b_blocknr);
654                                         if (bh_end <= pos || bh_pos >= end)
655                                                 mark_buffer_dirty(bh);
656                                         else
657                                                 set_buffer_new(bh);
658                                 }
659                                 continue;
660                         }
661                         /* Page is _not_ uptodate. */
662                         if (likely(!was_hole)) {
663                                 /*
664                                  * Buffer was already allocated.  If it is not
665                                  * uptodate and is only partially being written
666                                  * to, we need to read it in before the write,
667                                  * i.e. now.
668                                  */
669                                 if (!buffer_uptodate(bh) && bh_pos < end &&
670                                                 bh_end > pos &&
671                                                 (bh_pos < pos ||
672                                                 bh_end > end)) {
673                                         /*
674                                          * If the buffer is fully or partially
675                                          * within the initialized size, do an
676                                          * actual read.  Otherwise, simply zero
677                                          * the buffer.
678                                          */
679                                         read_lock_irqsave(&ni->size_lock,
680                                                         flags);
681                                         initialized_size = ni->initialized_size;
682                                         read_unlock_irqrestore(&ni->size_lock,
683                                                         flags);
684                                         if (bh_pos < initialized_size) {
685                                                 ntfs_submit_bh_for_read(bh);
686                                                 *wait_bh++ = bh;
687                                         } else {
688                                                 u8 *kaddr = kmap_atomic(page,
689                                                                 KM_USER0);
690                                                 memset(kaddr + bh_offset(bh),
691                                                                 0, blocksize);
692                                                 kunmap_atomic(kaddr, KM_USER0);
693                                                 flush_dcache_page(page);
694                                                 set_buffer_uptodate(bh);
695                                         }
696                                 }
697                                 continue;
698                         }
699                         /* We allocated the buffer. */
700                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
701                         /*
702                          * If the buffer is fully outside the write, zero it,
703                          * set it uptodate, and mark it dirty so it gets
704                          * written out.  If it is partially being written to,
705                          * zero region surrounding the write but leave it to
706                          * commit write to do anything else.  Finally, if the
707                          * buffer is fully being overwritten, do nothing.
708                          */
709                         if (bh_end <= pos || bh_pos >= end) {
710                                 if (!buffer_uptodate(bh)) {
711                                         u8 *kaddr = kmap_atomic(page, KM_USER0);
712                                         memset(kaddr + bh_offset(bh), 0,
713                                                         blocksize);
714                                         kunmap_atomic(kaddr, KM_USER0);
715                                         flush_dcache_page(page);
716                                         set_buffer_uptodate(bh);
717                                 }
718                                 mark_buffer_dirty(bh);
719                                 continue;
720                         }
721                         set_buffer_new(bh);
722                         if (!buffer_uptodate(bh) &&
723                                         (bh_pos < pos || bh_end > end)) {
724                                 u8 *kaddr;
725                                 unsigned pofs;
726                                         
727                                 kaddr = kmap_atomic(page, KM_USER0);
728                                 if (bh_pos < pos) {
729                                         pofs = bh_pos & ~PAGE_CACHE_MASK;
730                                         memset(kaddr + pofs, 0, pos - bh_pos);
731                                 }
732                                 if (bh_end > end) {
733                                         pofs = end & ~PAGE_CACHE_MASK;
734                                         memset(kaddr + pofs, 0, bh_end - end);
735                                 }
736                                 kunmap_atomic(kaddr, KM_USER0);
737                                 flush_dcache_page(page);
738                         }
739                         continue;
740                 }
741                 /*
742                  * Slow path: this is the first buffer in the cluster.  If it
743                  * is outside allocated size and is not uptodate, zero it and
744                  * set it uptodate.
745                  */
746                 read_lock_irqsave(&ni->size_lock, flags);
747                 initialized_size = ni->allocated_size;
748                 read_unlock_irqrestore(&ni->size_lock, flags);
749                 if (bh_pos > initialized_size) {
750                         if (PageUptodate(page)) {
751                                 if (!buffer_uptodate(bh))
752                                         set_buffer_uptodate(bh);
753                         } else if (!buffer_uptodate(bh)) {
754                                 u8 *kaddr = kmap_atomic(page, KM_USER0);
755                                 memset(kaddr + bh_offset(bh), 0, blocksize);
756                                 kunmap_atomic(kaddr, KM_USER0);
757                                 flush_dcache_page(page);
758                                 set_buffer_uptodate(bh);
759                         }
760                         continue;
761                 }
762                 is_retry = false;
763                 if (!rl) {
764                         down_read(&ni->runlist.lock);
765 retry_remap:
766                         rl = ni->runlist.rl;
767                 }
768                 if (likely(rl != NULL)) {
769                         /* Seek to element containing target cluster. */
770                         while (rl->length && rl[1].vcn <= bh_cpos)
771                                 rl++;
772                         lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
773                         if (likely(lcn >= 0)) {
774                                 /*
775                                  * Successful remap, setup the map cache and
776                                  * use that to deal with the buffer.
777                                  */
778                                 was_hole = false;
779                                 vcn = bh_cpos;
780                                 vcn_len = rl[1].vcn - vcn;
781                                 lcn_block = lcn << (vol->cluster_size_bits -
782                                                 blocksize_bits);
783                                 cdelta = 0;
784                                 /*
785                                  * If the number of remaining clusters touched
786                                  * by the write is smaller or equal to the
787                                  * number of cached clusters, unlock the
788                                  * runlist as the map cache will be used from
789                                  * now on.
790                                  */
791                                 if (likely(vcn + vcn_len >= cend)) {
792                                         if (rl_write_locked) {
793                                                 up_write(&ni->runlist.lock);
794                                                 rl_write_locked = false;
795                                         } else
796                                                 up_read(&ni->runlist.lock);
797                                         rl = NULL;
798                                 }
799                                 goto map_buffer_cached;
800                         }
801                 } else
802                         lcn = LCN_RL_NOT_MAPPED;
803                 /*
804                  * If it is not a hole and not out of bounds, the runlist is
805                  * probably unmapped so try to map it now.
806                  */
807                 if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
808                         if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
809                                 /* Attempt to map runlist. */
810                                 if (!rl_write_locked) {
811                                         /*
812                                          * We need the runlist locked for
813                                          * writing, so if it is locked for
814                                          * reading relock it now and retry in
815                                          * case it changed whilst we dropped
816                                          * the lock.
817                                          */
818                                         up_read(&ni->runlist.lock);
819                                         down_write(&ni->runlist.lock);
820                                         rl_write_locked = true;
821                                         goto retry_remap;
822                                 }
823                                 err = ntfs_map_runlist_nolock(ni, bh_cpos,
824                                                 NULL);
825                                 if (likely(!err)) {
826                                         is_retry = true;
827                                         goto retry_remap;
828                                 }
829                                 /*
830                                  * If @vcn is out of bounds, pretend @lcn is
831                                  * LCN_ENOENT.  As long as the buffer is out
832                                  * of bounds this will work fine.
833                                  */
834                                 if (err == -ENOENT) {
835                                         lcn = LCN_ENOENT;
836                                         err = 0;
837                                         goto rl_not_mapped_enoent;
838                                 }
839                         } else
840                                 err = -EIO;
841                         /* Failed to map the buffer, even after retrying. */
842                         bh->b_blocknr = -1;
843                         ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
844                                         "attribute type 0x%x, vcn 0x%llx, "
845                                         "vcn offset 0x%x, because its "
846                                         "location on disk could not be "
847                                         "determined%s (error code %i).",
848                                         ni->mft_no, ni->type,
849                                         (unsigned long long)bh_cpos,
850                                         (unsigned)bh_pos &
851                                         vol->cluster_size_mask,
852                                         is_retry ? " even after retrying" : "",
853                                         err);
854                         break;
855                 }
856 rl_not_mapped_enoent:
857                 /*
858                  * The buffer is in a hole or out of bounds.  We need to fill
859                  * the hole, unless the buffer is in a cluster which is not
860                  * touched by the write, in which case we just leave the buffer
861                  * unmapped.  This can only happen when the cluster size is
862                  * less than the page cache size.
863                  */
864                 if (unlikely(vol->cluster_size < PAGE_CACHE_SIZE)) {
865                         bh_cend = (bh_end + vol->cluster_size - 1) >>
866                                         vol->cluster_size_bits;
867                         if ((bh_cend <= cpos || bh_cpos >= cend)) {
868                                 bh->b_blocknr = -1;
869                                 /*
870                                  * If the buffer is uptodate we skip it.  If it
871                                  * is not but the page is uptodate, we can set
872                                  * the buffer uptodate.  If the page is not
873                                  * uptodate, we can clear the buffer and set it
874                                  * uptodate.  Whether this is worthwhile is
875                                  * debatable and this could be removed.
876                                  */
877                                 if (PageUptodate(page)) {
878                                         if (!buffer_uptodate(bh))
879                                                 set_buffer_uptodate(bh);
880                                 } else if (!buffer_uptodate(bh)) {
881                                         u8 *kaddr = kmap_atomic(page, KM_USER0);
882                                         memset(kaddr + bh_offset(bh), 0,
883                                                         blocksize);
884                                         kunmap_atomic(kaddr, KM_USER0);
885                                         flush_dcache_page(page);
886                                         set_buffer_uptodate(bh);
887                                 }
888                                 continue;
889                         }
890                 }
891                 /*
892                  * Out of bounds buffer is invalid if it was not really out of
893                  * bounds.
894                  */
895                 BUG_ON(lcn != LCN_HOLE);
896                 /*
897                  * We need the runlist locked for writing, so if it is locked
898                  * for reading relock it now and retry in case it changed
899                  * whilst we dropped the lock.
900                  */
901                 BUG_ON(!rl);
902                 if (!rl_write_locked) {
903                         up_read(&ni->runlist.lock);
904                         down_write(&ni->runlist.lock);
905                         rl_write_locked = true;
906                         goto retry_remap;
907                 }
908                 /* Find the previous last allocated cluster. */
909                 BUG_ON(rl->lcn != LCN_HOLE);
910                 lcn = -1;
911                 rl2 = rl;
912                 while (--rl2 >= ni->runlist.rl) {
913                         if (rl2->lcn >= 0) {
914                                 lcn = rl2->lcn + rl2->length;
915                                 break;
916                         }
917                 }
918                 rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
919                                 false);
920                 if (IS_ERR(rl2)) {
921                         err = PTR_ERR(rl2);
922                         ntfs_debug("Failed to allocate cluster, error code %i.",
923                                         err);
924                         break;
925                 }
926                 lcn = rl2->lcn;
927                 rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
928                 if (IS_ERR(rl)) {
929                         err = PTR_ERR(rl);
930                         if (err != -ENOMEM)
931                                 err = -EIO;
932                         if (ntfs_cluster_free_from_rl(vol, rl2)) {
933                                 ntfs_error(vol->sb, "Failed to release "
934                                                 "allocated cluster in error "
935                                                 "code path.  Run chkdsk to "
936                                                 "recover the lost cluster.");
937                                 NVolSetErrors(vol);
938                         }
939                         ntfs_free(rl2);
940                         break;
941                 }
942                 ni->runlist.rl = rl;
943                 status.runlist_merged = 1;
944                 ntfs_debug("Allocated cluster, lcn 0x%llx.",
945                                 (unsigned long long)lcn);
946                 /* Map and lock the mft record and get the attribute record. */
947                 if (!NInoAttr(ni))
948                         base_ni = ni;
949                 else
950                         base_ni = ni->ext.base_ntfs_ino;
951                 m = map_mft_record(base_ni);
952                 if (IS_ERR(m)) {
953                         err = PTR_ERR(m);
954                         break;
955                 }
956                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
957                 if (unlikely(!ctx)) {
958                         err = -ENOMEM;
959                         unmap_mft_record(base_ni);
960                         break;
961                 }
962                 status.mft_attr_mapped = 1;
963                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
964                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
965                 if (unlikely(err)) {
966                         if (err == -ENOENT)
967                                 err = -EIO;
968                         break;
969                 }
970                 m = ctx->mrec;
971                 a = ctx->attr;
972                 /*
973                  * Find the runlist element with which the attribute extent
974                  * starts.  Note, we cannot use the _attr_ version because we
975                  * have mapped the mft record.  That is ok because we know the
976                  * runlist fragment must be mapped already to have ever gotten
977                  * here, so we can just use the _rl_ version.
978                  */
979                 vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
980                 rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
981                 BUG_ON(!rl2);
982                 BUG_ON(!rl2->length);
983                 BUG_ON(rl2->lcn < LCN_HOLE);
984                 highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
985                 /*
986                  * If @highest_vcn is zero, calculate the real highest_vcn
987                  * (which can really be zero).
988                  */
989                 if (!highest_vcn)
990                         highest_vcn = (sle64_to_cpu(
991                                         a->data.non_resident.allocated_size) >>
992                                         vol->cluster_size_bits) - 1;
993                 /*
994                  * Determine the size of the mapping pairs array for the new
995                  * extent, i.e. the old extent with the hole filled.
996                  */
997                 mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
998                                 highest_vcn);
999                 if (unlikely(mp_size <= 0)) {
1000                         if (!(err = mp_size))
1001                                 err = -EIO;
1002                         ntfs_debug("Failed to get size for mapping pairs "
1003                                         "array, error code %i.", err);
1004                         break;
1005                 }
1006                 /*
1007                  * Resize the attribute record to fit the new mapping pairs
1008                  * array.
1009                  */
1010                 attr_rec_len = le32_to_cpu(a->length);
1011                 err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
1012                                 a->data.non_resident.mapping_pairs_offset));
1013                 if (unlikely(err)) {
1014                         BUG_ON(err != -ENOSPC);
1015                         // TODO: Deal with this by using the current attribute
1016                         // and fill it with as much of the mapping pairs
1017                         // array as possible.  Then loop over each attribute
1018                         // extent rewriting the mapping pairs arrays as we go
1019                         // along and if when we reach the end we have not
1020                         // enough space, try to resize the last attribute
1021                         // extent and if even that fails, add a new attribute
1022                         // extent.
1023                         // We could also try to resize at each step in the hope
1024                         // that we will not need to rewrite every single extent.
1025                         // Note, we may need to decompress some extents to fill
1026                         // the runlist as we are walking the extents...
1027                         ntfs_error(vol->sb, "Not enough space in the mft "
1028                                         "record for the extended attribute "
1029                                         "record.  This case is not "
1030                                         "implemented yet.");
1031                         err = -EOPNOTSUPP;
1032                         break ;
1033                 }
1034                 status.mp_rebuilt = 1;
1035                 /*
1036                  * Generate the mapping pairs array directly into the attribute
1037                  * record.
1038                  */
1039                 err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1040                                 a->data.non_resident.mapping_pairs_offset),
1041                                 mp_size, rl2, vcn, highest_vcn, NULL);
1042                 if (unlikely(err)) {
1043                         ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1044                                         "attribute type 0x%x, because building "
1045                                         "the mapping pairs failed with error "
1046                                         "code %i.", vi->i_ino,
1047                                         (unsigned)le32_to_cpu(ni->type), err);
1048                         err = -EIO;
1049                         break;
1050                 }
1051                 /* Update the highest_vcn but only if it was not set. */
1052                 if (unlikely(!a->data.non_resident.highest_vcn))
1053                         a->data.non_resident.highest_vcn =
1054                                         cpu_to_sle64(highest_vcn);
1055                 /*
1056                  * If the attribute is sparse/compressed, update the compressed
1057                  * size in the ntfs_inode structure and the attribute record.
1058                  */
1059                 if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1060                         /*
1061                          * If we are not in the first attribute extent, switch
1062                          * to it, but first ensure the changes will make it to
1063                          * disk later.
1064                          */
1065                         if (a->data.non_resident.lowest_vcn) {
1066                                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1067                                 mark_mft_record_dirty(ctx->ntfs_ino);
1068                                 ntfs_attr_reinit_search_ctx(ctx);
1069                                 err = ntfs_attr_lookup(ni->type, ni->name,
1070                                                 ni->name_len, CASE_SENSITIVE,
1071                                                 0, NULL, 0, ctx);
1072                                 if (unlikely(err)) {
1073                                         status.attr_switched = 1;
1074                                         break;
1075                                 }
1076                                 /* @m is not used any more so do not set it. */
1077                                 a = ctx->attr;
1078                         }
1079                         write_lock_irqsave(&ni->size_lock, flags);
1080                         ni->itype.compressed.size += vol->cluster_size;
1081                         a->data.non_resident.compressed_size =
1082                                         cpu_to_sle64(ni->itype.compressed.size);
1083                         write_unlock_irqrestore(&ni->size_lock, flags);
1084                 }
1085                 /* Ensure the changes make it to disk. */
1086                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1087                 mark_mft_record_dirty(ctx->ntfs_ino);
1088                 ntfs_attr_put_search_ctx(ctx);
1089                 unmap_mft_record(base_ni);
1090                 /* Successfully filled the hole. */
1091                 status.runlist_merged = 0;
1092                 status.mft_attr_mapped = 0;
1093                 status.mp_rebuilt = 0;
1094                 /* Setup the map cache and use that to deal with the buffer. */
1095                 was_hole = true;
1096                 vcn = bh_cpos;
1097                 vcn_len = 1;
1098                 lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1099                 cdelta = 0;
1100                 /*
1101                  * If the number of remaining clusters in the @pages is smaller
1102                  * or equal to the number of cached clusters, unlock the
1103                  * runlist as the map cache will be used from now on.
1104                  */
1105                 if (likely(vcn + vcn_len >= cend)) {
1106                         up_write(&ni->runlist.lock);
1107                         rl_write_locked = false;
1108                         rl = NULL;
1109                 }
1110                 goto map_buffer_cached;
1111         } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1112         /* If there are no errors, do the next page. */
1113         if (likely(!err && ++u < nr_pages))
1114                 goto do_next_page;
1115         /* If there are no errors, release the runlist lock if we took it. */
1116         if (likely(!err)) {
1117                 if (unlikely(rl_write_locked)) {
1118                         up_write(&ni->runlist.lock);
1119                         rl_write_locked = false;
1120                 } else if (unlikely(rl))
1121                         up_read(&ni->runlist.lock);
1122                 rl = NULL;
1123         }
1124         /* If we issued read requests, let them complete. */
1125         read_lock_irqsave(&ni->size_lock, flags);
1126         initialized_size = ni->initialized_size;
1127         read_unlock_irqrestore(&ni->size_lock, flags);
1128         while (wait_bh > wait) {
1129                 bh = *--wait_bh;
1130                 wait_on_buffer(bh);
1131                 if (likely(buffer_uptodate(bh))) {
1132                         page = bh->b_page;
1133                         bh_pos = ((s64)page->index << PAGE_CACHE_SHIFT) +
1134                                         bh_offset(bh);
1135                         /*
1136                          * If the buffer overflows the initialized size, need
1137                          * to zero the overflowing region.
1138                          */
1139                         if (unlikely(bh_pos + blocksize > initialized_size)) {
1140                                 u8 *kaddr;
1141                                 int ofs = 0;
1142
1143                                 if (likely(bh_pos < initialized_size))
1144                                         ofs = initialized_size - bh_pos;
1145                                 kaddr = kmap_atomic(page, KM_USER0);
1146                                 memset(kaddr + bh_offset(bh) + ofs, 0,
1147                                                 blocksize - ofs);
1148                                 kunmap_atomic(kaddr, KM_USER0);
1149                                 flush_dcache_page(page);
1150                         }
1151                 } else /* if (unlikely(!buffer_uptodate(bh))) */
1152                         err = -EIO;
1153         }
1154         if (likely(!err)) {
1155                 /* Clear buffer_new on all buffers. */
1156                 u = 0;
1157                 do {
1158                         bh = head = page_buffers(pages[u]);
1159                         do {
1160                                 if (buffer_new(bh))
1161                                         clear_buffer_new(bh);
1162                         } while ((bh = bh->b_this_page) != head);
1163                 } while (++u < nr_pages);
1164                 ntfs_debug("Done.");
1165                 return err;
1166         }
1167         if (status.attr_switched) {
1168                 /* Get back to the attribute extent we modified. */
1169                 ntfs_attr_reinit_search_ctx(ctx);
1170                 if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1171                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1172                         ntfs_error(vol->sb, "Failed to find required "
1173                                         "attribute extent of attribute in "
1174                                         "error code path.  Run chkdsk to "
1175                                         "recover.");
1176                         write_lock_irqsave(&ni->size_lock, flags);
1177                         ni->itype.compressed.size += vol->cluster_size;
1178                         write_unlock_irqrestore(&ni->size_lock, flags);
1179                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1180                         mark_mft_record_dirty(ctx->ntfs_ino);
1181                         /*
1182                          * The only thing that is now wrong is the compressed
1183                          * size of the base attribute extent which chkdsk
1184                          * should be able to fix.
1185                          */
1186                         NVolSetErrors(vol);
1187                 } else {
1188                         m = ctx->mrec;
1189                         a = ctx->attr;
1190                         status.attr_switched = 0;
1191                 }
1192         }
1193         /*
1194          * If the runlist has been modified, need to restore it by punching a
1195          * hole into it and we then need to deallocate the on-disk cluster as
1196          * well.  Note, we only modify the runlist if we are able to generate a
1197          * new mapping pairs array, i.e. only when the mapped attribute extent
1198          * is not switched.
1199          */
1200         if (status.runlist_merged && !status.attr_switched) {
1201                 BUG_ON(!rl_write_locked);
1202                 /* Make the file cluster we allocated sparse in the runlist. */
1203                 if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1204                         ntfs_error(vol->sb, "Failed to punch hole into "
1205                                         "attribute runlist in error code "
1206                                         "path.  Run chkdsk to recover the "
1207                                         "lost cluster.");
1208                         NVolSetErrors(vol);
1209                 } else /* if (success) */ {
1210                         status.runlist_merged = 0;
1211                         /*
1212                          * Deallocate the on-disk cluster we allocated but only
1213                          * if we succeeded in punching its vcn out of the
1214                          * runlist.
1215                          */
1216                         down_write(&vol->lcnbmp_lock);
1217                         if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1218                                 ntfs_error(vol->sb, "Failed to release "
1219                                                 "allocated cluster in error "
1220                                                 "code path.  Run chkdsk to "
1221                                                 "recover the lost cluster.");
1222                                 NVolSetErrors(vol);
1223                         }
1224                         up_write(&vol->lcnbmp_lock);
1225                 }
1226         }
1227         /*
1228          * Resize the attribute record to its old size and rebuild the mapping
1229          * pairs array.  Note, we only can do this if the runlist has been
1230          * restored to its old state which also implies that the mapped
1231          * attribute extent is not switched.
1232          */
1233         if (status.mp_rebuilt && !status.runlist_merged) {
1234                 if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1235                         ntfs_error(vol->sb, "Failed to restore attribute "
1236                                         "record in error code path.  Run "
1237                                         "chkdsk to recover.");
1238                         NVolSetErrors(vol);
1239                 } else /* if (success) */ {
1240                         if (ntfs_mapping_pairs_build(vol, (u8*)a +
1241                                         le16_to_cpu(a->data.non_resident.
1242                                         mapping_pairs_offset), attr_rec_len -
1243                                         le16_to_cpu(a->data.non_resident.
1244                                         mapping_pairs_offset), ni->runlist.rl,
1245                                         vcn, highest_vcn, NULL)) {
1246                                 ntfs_error(vol->sb, "Failed to restore "
1247                                                 "mapping pairs array in error "
1248                                                 "code path.  Run chkdsk to "
1249                                                 "recover.");
1250                                 NVolSetErrors(vol);
1251                         }
1252                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1253                         mark_mft_record_dirty(ctx->ntfs_ino);
1254                 }
1255         }
1256         /* Release the mft record and the attribute. */
1257         if (status.mft_attr_mapped) {
1258                 ntfs_attr_put_search_ctx(ctx);
1259                 unmap_mft_record(base_ni);
1260         }
1261         /* Release the runlist lock. */
1262         if (rl_write_locked)
1263                 up_write(&ni->runlist.lock);
1264         else if (rl)
1265                 up_read(&ni->runlist.lock);
1266         /*
1267          * Zero out any newly allocated blocks to avoid exposing stale data.
1268          * If BH_New is set, we know that the block was newly allocated above
1269          * and that it has not been fully zeroed and marked dirty yet.
1270          */
1271         nr_pages = u;
1272         u = 0;
1273         end = bh_cpos << vol->cluster_size_bits;
1274         do {
1275                 page = pages[u];
1276                 bh = head = page_buffers(page);
1277                 do {
1278                         if (u == nr_pages &&
1279                                         ((s64)page->index << PAGE_CACHE_SHIFT) +
1280                                         bh_offset(bh) >= end)
1281                                 break;
1282                         if (!buffer_new(bh))
1283                                 continue;
1284                         clear_buffer_new(bh);
1285                         if (!buffer_uptodate(bh)) {
1286                                 if (PageUptodate(page))
1287                                         set_buffer_uptodate(bh);
1288                                 else {
1289                                         u8 *kaddr = kmap_atomic(page, KM_USER0);
1290                                         memset(kaddr + bh_offset(bh), 0,
1291                                                         blocksize);
1292                                         kunmap_atomic(kaddr, KM_USER0);
1293                                         flush_dcache_page(page);
1294                                         set_buffer_uptodate(bh);
1295                                 }
1296                         }
1297                         mark_buffer_dirty(bh);
1298                 } while ((bh = bh->b_this_page) != head);
1299         } while (++u <= nr_pages);
1300         ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1301         return err;
1302 }
1303
1304 /*
1305  * Copy as much as we can into the pages and return the number of bytes which
1306  * were sucessfully copied.  If a fault is encountered then clear the pages
1307  * out to (ofs + bytes) and return the number of bytes which were copied.
1308  */
1309 static inline size_t ntfs_copy_from_user(struct page **pages,
1310                 unsigned nr_pages, unsigned ofs, const char __user *buf,
1311                 size_t bytes)
1312 {
1313         struct page **last_page = pages + nr_pages;
1314         char *kaddr;
1315         size_t total = 0;
1316         unsigned len;
1317         int left;
1318
1319         do {
1320                 len = PAGE_CACHE_SIZE - ofs;
1321                 if (len > bytes)
1322                         len = bytes;
1323                 kaddr = kmap_atomic(*pages, KM_USER0);
1324                 left = __copy_from_user_inatomic(kaddr + ofs, buf, len);
1325                 kunmap_atomic(kaddr, KM_USER0);
1326                 if (unlikely(left)) {
1327                         /* Do it the slow way. */
1328                         kaddr = kmap(*pages);
1329                         left = __copy_from_user(kaddr + ofs, buf, len);
1330                         kunmap(*pages);
1331                         if (unlikely(left))
1332                                 goto err_out;
1333                 }
1334                 total += len;
1335                 bytes -= len;
1336                 if (!bytes)
1337                         break;
1338                 buf += len;
1339                 ofs = 0;
1340         } while (++pages < last_page);
1341 out:
1342         return total;
1343 err_out:
1344         total += len - left;
1345         /* Zero the rest of the target like __copy_from_user(). */
1346         while (++pages < last_page) {
1347                 bytes -= len;
1348                 if (!bytes)
1349                         break;
1350                 len = PAGE_CACHE_SIZE;
1351                 if (len > bytes)
1352                         len = bytes;
1353                 kaddr = kmap_atomic(*pages, KM_USER0);
1354                 memset(kaddr, 0, len);
1355                 kunmap_atomic(kaddr, KM_USER0);
1356         }
1357         goto out;
1358 }
1359
1360 static size_t __ntfs_copy_from_user_iovec_inatomic(char *vaddr,
1361                 const struct iovec *iov, size_t iov_ofs, size_t bytes)
1362 {
1363         size_t total = 0;
1364
1365         while (1) {
1366                 const char __user *buf = iov->iov_base + iov_ofs;
1367                 unsigned len;
1368                 size_t left;
1369
1370                 len = iov->iov_len - iov_ofs;
1371                 if (len > bytes)
1372                         len = bytes;
1373                 left = __copy_from_user_inatomic(vaddr, buf, len);
1374                 total += len;
1375                 bytes -= len;
1376                 vaddr += len;
1377                 if (unlikely(left)) {
1378                         total -= left;
1379                         break;
1380                 }
1381                 if (!bytes)
1382                         break;
1383                 iov++;
1384                 iov_ofs = 0;
1385         }
1386         return total;
1387 }
1388
1389 static inline void ntfs_set_next_iovec(const struct iovec **iovp,
1390                 size_t *iov_ofsp, size_t bytes)
1391 {
1392         const struct iovec *iov = *iovp;
1393         size_t iov_ofs = *iov_ofsp;
1394
1395         while (bytes) {
1396                 unsigned len;
1397
1398                 len = iov->iov_len - iov_ofs;
1399                 if (len > bytes)
1400                         len = bytes;
1401                 bytes -= len;
1402                 iov_ofs += len;
1403                 if (iov->iov_len == iov_ofs) {
1404                         iov++;
1405                         iov_ofs = 0;
1406                 }
1407         }
1408         *iovp = iov;
1409         *iov_ofsp = iov_ofs;
1410 }
1411
1412 /*
1413  * This has the same side-effects and return value as ntfs_copy_from_user().
1414  * The difference is that on a fault we need to memset the remainder of the
1415  * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
1416  * single-segment behaviour.
1417  *
1418  * We call the same helper (__ntfs_copy_from_user_iovec_inatomic()) both
1419  * when atomic and when not atomic.  This is ok because
1420  * __ntfs_copy_from_user_iovec_inatomic() calls __copy_from_user_inatomic()
1421  * and it is ok to call this when non-atomic.
1422  * Infact, the only difference between __copy_from_user_inatomic() and
1423  * __copy_from_user() is that the latter calls might_sleep() and the former
1424  * should not zero the tail of the buffer on error.  And on many
1425  * architectures __copy_from_user_inatomic() is just defined to
1426  * __copy_from_user() so it makes no difference at all on those architectures.
1427  */
1428 static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
1429                 unsigned nr_pages, unsigned ofs, const struct iovec **iov,
1430                 size_t *iov_ofs, size_t bytes)
1431 {
1432         struct page **last_page = pages + nr_pages;
1433         char *kaddr;
1434         size_t copied, len, total = 0;
1435
1436         do {
1437                 len = PAGE_CACHE_SIZE - ofs;
1438                 if (len > bytes)
1439                         len = bytes;
1440                 kaddr = kmap_atomic(*pages, KM_USER0);
1441                 copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
1442                                 *iov, *iov_ofs, len);
1443                 kunmap_atomic(kaddr, KM_USER0);
1444                 if (unlikely(copied != len)) {
1445                         /* Do it the slow way. */
1446                         kaddr = kmap(*pages);
1447                         copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
1448                                         *iov, *iov_ofs, len);
1449                         /*
1450                          * Zero the rest of the target like __copy_from_user().
1451                          */
1452                         memset(kaddr + ofs + copied, 0, len - copied);
1453                         kunmap(*pages);
1454                         if (unlikely(copied != len))
1455                                 goto err_out;
1456                 }
1457                 total += len;
1458                 bytes -= len;
1459                 if (!bytes)
1460                         break;
1461                 ntfs_set_next_iovec(iov, iov_ofs, len);
1462                 ofs = 0;
1463         } while (++pages < last_page);
1464 out:
1465         return total;
1466 err_out:
1467         total += copied;
1468         /* Zero the rest of the target like __copy_from_user(). */
1469         while (++pages < last_page) {
1470                 bytes -= len;
1471                 if (!bytes)
1472                         break;
1473                 len = PAGE_CACHE_SIZE;
1474                 if (len > bytes)
1475                         len = bytes;
1476                 kaddr = kmap_atomic(*pages, KM_USER0);
1477                 memset(kaddr, 0, len);
1478                 kunmap_atomic(kaddr, KM_USER0);
1479         }
1480         goto out;
1481 }
1482
1483 static inline void ntfs_flush_dcache_pages(struct page **pages,
1484                 unsigned nr_pages)
1485 {
1486         BUG_ON(!nr_pages);
1487         /*
1488          * Warning: Do not do the decrement at the same time as the call to
1489          * flush_dcache_page() because it is a NULL macro on i386 and hence the
1490          * decrement never happens so the loop never terminates.
1491          */
1492         do {
1493                 --nr_pages;
1494                 flush_dcache_page(pages[nr_pages]);
1495         } while (nr_pages > 0);
1496 }
1497
1498 /**
1499  * ntfs_commit_pages_after_non_resident_write - commit the received data
1500  * @pages:      array of destination pages
1501  * @nr_pages:   number of pages in @pages
1502  * @pos:        byte position in file at which the write begins
1503  * @bytes:      number of bytes to be written
1504  *
1505  * See description of ntfs_commit_pages_after_write(), below.
1506  */
1507 static inline int ntfs_commit_pages_after_non_resident_write(
1508                 struct page **pages, const unsigned nr_pages,
1509                 s64 pos, size_t bytes)
1510 {
1511         s64 end, initialized_size;
1512         struct inode *vi;
1513         ntfs_inode *ni, *base_ni;
1514         struct buffer_head *bh, *head;
1515         ntfs_attr_search_ctx *ctx;
1516         MFT_RECORD *m;
1517         ATTR_RECORD *a;
1518         unsigned long flags;
1519         unsigned blocksize, u;
1520         int err;
1521
1522         vi = pages[0]->mapping->host;
1523         ni = NTFS_I(vi);
1524         blocksize = vi->i_sb->s_blocksize;
1525         end = pos + bytes;
1526         u = 0;
1527         do {
1528                 s64 bh_pos;
1529                 struct page *page;
1530                 bool partial;
1531
1532                 page = pages[u];
1533                 bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
1534                 bh = head = page_buffers(page);
1535                 partial = false;
1536                 do {
1537                         s64 bh_end;
1538
1539                         bh_end = bh_pos + blocksize;
1540                         if (bh_end <= pos || bh_pos >= end) {
1541                                 if (!buffer_uptodate(bh))
1542                                         partial = true;
1543                         } else {
1544                                 set_buffer_uptodate(bh);
1545                                 mark_buffer_dirty(bh);
1546                         }
1547                 } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1548                 /*
1549                  * If all buffers are now uptodate but the page is not, set the
1550                  * page uptodate.
1551                  */
1552                 if (!partial && !PageUptodate(page))
1553                         SetPageUptodate(page);
1554         } while (++u < nr_pages);
1555         /*
1556          * Finally, if we do not need to update initialized_size or i_size we
1557          * are finished.
1558          */
1559         read_lock_irqsave(&ni->size_lock, flags);
1560         initialized_size = ni->initialized_size;
1561         read_unlock_irqrestore(&ni->size_lock, flags);
1562         if (end <= initialized_size) {
1563                 ntfs_debug("Done.");
1564                 return 0;
1565         }
1566         /*
1567          * Update initialized_size/i_size as appropriate, both in the inode and
1568          * the mft record.
1569          */
1570         if (!NInoAttr(ni))
1571                 base_ni = ni;
1572         else
1573                 base_ni = ni->ext.base_ntfs_ino;
1574         /* Map, pin, and lock the mft record. */
1575         m = map_mft_record(base_ni);
1576         if (IS_ERR(m)) {
1577                 err = PTR_ERR(m);
1578                 m = NULL;
1579                 ctx = NULL;
1580                 goto err_out;
1581         }
1582         BUG_ON(!NInoNonResident(ni));
1583         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1584         if (unlikely(!ctx)) {
1585                 err = -ENOMEM;
1586                 goto err_out;
1587         }
1588         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1589                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1590         if (unlikely(err)) {
1591                 if (err == -ENOENT)
1592                         err = -EIO;
1593                 goto err_out;
1594         }
1595         a = ctx->attr;
1596         BUG_ON(!a->non_resident);
1597         write_lock_irqsave(&ni->size_lock, flags);
1598         BUG_ON(end > ni->allocated_size);
1599         ni->initialized_size = end;
1600         a->data.non_resident.initialized_size = cpu_to_sle64(end);
1601         if (end > i_size_read(vi)) {
1602                 i_size_write(vi, end);
1603                 a->data.non_resident.data_size =
1604                                 a->data.non_resident.initialized_size;
1605         }
1606         write_unlock_irqrestore(&ni->size_lock, flags);
1607         /* Mark the mft record dirty, so it gets written back. */
1608         flush_dcache_mft_record_page(ctx->ntfs_ino);
1609         mark_mft_record_dirty(ctx->ntfs_ino);
1610         ntfs_attr_put_search_ctx(ctx);
1611         unmap_mft_record(base_ni);
1612         ntfs_debug("Done.");
1613         return 0;
1614 err_out:
1615         if (ctx)
1616                 ntfs_attr_put_search_ctx(ctx);
1617         if (m)
1618                 unmap_mft_record(base_ni);
1619         ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1620                         "code %i).", err);
1621         if (err != -ENOMEM)
1622                 NVolSetErrors(ni->vol);
1623         return err;
1624 }
1625
1626 /**
1627  * ntfs_commit_pages_after_write - commit the received data
1628  * @pages:      array of destination pages
1629  * @nr_pages:   number of pages in @pages
1630  * @pos:        byte position in file at which the write begins
1631  * @bytes:      number of bytes to be written
1632  *
1633  * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
1634  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1635  * locked but not kmap()ped.  The source data has already been copied into the
1636  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1637  * the data was copied (for non-resident attributes only) and it returned
1638  * success.
1639  *
1640  * Need to set uptodate and mark dirty all buffers within the boundary of the
1641  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1642  *
1643  * Setting the buffers dirty ensures that they get written out later when
1644  * ntfs_writepage() is invoked by the VM.
1645  *
1646  * Finally, we need to update i_size and initialized_size as appropriate both
1647  * in the inode and the mft record.
1648  *
1649  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1650  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1651  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1652  * that case, it also marks the inode dirty.
1653  *
1654  * If things have gone as outlined in
1655  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1656  * content modifications here for non-resident attributes.  For resident
1657  * attributes we need to do the uptodate bringing here which we combine with
1658  * the copying into the mft record which means we save one atomic kmap.
1659  *
1660  * Return 0 on success or -errno on error.
1661  */
1662 static int ntfs_commit_pages_after_write(struct page **pages,
1663                 const unsigned nr_pages, s64 pos, size_t bytes)
1664 {
1665         s64 end, initialized_size;
1666         loff_t i_size;
1667         struct inode *vi;
1668         ntfs_inode *ni, *base_ni;
1669         struct page *page;
1670         ntfs_attr_search_ctx *ctx;
1671         MFT_RECORD *m;
1672         ATTR_RECORD *a;
1673         char *kattr, *kaddr;
1674         unsigned long flags;
1675         u32 attr_len;
1676         int err;
1677
1678         BUG_ON(!nr_pages);
1679         BUG_ON(!pages);
1680         page = pages[0];
1681         BUG_ON(!page);
1682         vi = page->mapping->host;
1683         ni = NTFS_I(vi);
1684         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1685                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1686                         vi->i_ino, ni->type, page->index, nr_pages,
1687                         (long long)pos, bytes);
1688         if (NInoNonResident(ni))
1689                 return ntfs_commit_pages_after_non_resident_write(pages,
1690                                 nr_pages, pos, bytes);
1691         BUG_ON(nr_pages > 1);
1692         /*
1693          * Attribute is resident, implying it is not compressed, encrypted, or
1694          * sparse.
1695          */
1696         if (!NInoAttr(ni))
1697                 base_ni = ni;
1698         else
1699                 base_ni = ni->ext.base_ntfs_ino;
1700         BUG_ON(NInoNonResident(ni));
1701         /* Map, pin, and lock the mft record. */
1702         m = map_mft_record(base_ni);
1703         if (IS_ERR(m)) {
1704                 err = PTR_ERR(m);
1705                 m = NULL;
1706                 ctx = NULL;
1707                 goto err_out;
1708         }
1709         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1710         if (unlikely(!ctx)) {
1711                 err = -ENOMEM;
1712                 goto err_out;
1713         }
1714         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1715                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1716         if (unlikely(err)) {
1717                 if (err == -ENOENT)
1718                         err = -EIO;
1719                 goto err_out;
1720         }
1721         a = ctx->attr;
1722         BUG_ON(a->non_resident);
1723         /* The total length of the attribute value. */
1724         attr_len = le32_to_cpu(a->data.resident.value_length);
1725         i_size = i_size_read(vi);
1726         BUG_ON(attr_len != i_size);
1727         BUG_ON(pos > attr_len);
1728         end = pos + bytes;
1729         BUG_ON(end > le32_to_cpu(a->length) -
1730                         le16_to_cpu(a->data.resident.value_offset));
1731         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1732         kaddr = kmap_atomic(page, KM_USER0);
1733         /* Copy the received data from the page to the mft record. */
1734         memcpy(kattr + pos, kaddr + pos, bytes);
1735         /* Update the attribute length if necessary. */
1736         if (end > attr_len) {
1737                 attr_len = end;
1738                 a->data.resident.value_length = cpu_to_le32(attr_len);
1739         }
1740         /*
1741          * If the page is not uptodate, bring the out of bounds area(s)
1742          * uptodate by copying data from the mft record to the page.
1743          */
1744         if (!PageUptodate(page)) {
1745                 if (pos > 0)
1746                         memcpy(kaddr, kattr, pos);
1747                 if (end < attr_len)
1748                         memcpy(kaddr + end, kattr + end, attr_len - end);
1749                 /* Zero the region outside the end of the attribute value. */
1750                 memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1751                 flush_dcache_page(page);
1752                 SetPageUptodate(page);
1753         }
1754         kunmap_atomic(kaddr, KM_USER0);
1755         /* Update initialized_size/i_size if necessary. */
1756         read_lock_irqsave(&ni->size_lock, flags);
1757         initialized_size = ni->initialized_size;
1758         BUG_ON(end > ni->allocated_size);
1759         read_unlock_irqrestore(&ni->size_lock, flags);
1760         BUG_ON(initialized_size != i_size);
1761         if (end > initialized_size) {
1762                 unsigned long flags;
1763
1764                 write_lock_irqsave(&ni->size_lock, flags);
1765                 ni->initialized_size = end;
1766                 i_size_write(vi, end);
1767                 write_unlock_irqrestore(&ni->size_lock, flags);
1768         }
1769         /* Mark the mft record dirty, so it gets written back. */
1770         flush_dcache_mft_record_page(ctx->ntfs_ino);
1771         mark_mft_record_dirty(ctx->ntfs_ino);
1772         ntfs_attr_put_search_ctx(ctx);
1773         unmap_mft_record(base_ni);
1774         ntfs_debug("Done.");
1775         return 0;
1776 err_out:
1777         if (err == -ENOMEM) {
1778                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
1779                                 "commit the write.");
1780                 if (PageUptodate(page)) {
1781                         ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1782                                         "dirty so the write will be retried "
1783                                         "later on by the VM.");
1784                         /*
1785                          * Put the page on mapping->dirty_pages, but leave its
1786                          * buffers' dirty state as-is.
1787                          */
1788                         __set_page_dirty_nobuffers(page);
1789                         err = 0;
1790                 } else
1791                         ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1792                                         "data has been lost.");
1793         } else {
1794                 ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1795                                 "with error %i.", err);
1796                 NVolSetErrors(ni->vol);
1797         }
1798         if (ctx)
1799                 ntfs_attr_put_search_ctx(ctx);
1800         if (m)
1801                 unmap_mft_record(base_ni);
1802         return err;
1803 }
1804
1805 /**
1806  * ntfs_file_buffered_write -
1807  *
1808  * Locking: The vfs is holding ->i_mutex on the inode.
1809  */
1810 static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
1811                 const struct iovec *iov, unsigned long nr_segs,
1812                 loff_t pos, loff_t *ppos, size_t count)
1813 {
1814         struct file *file = iocb->ki_filp;
1815         struct address_space *mapping = file->f_mapping;
1816         struct inode *vi = mapping->host;
1817         ntfs_inode *ni = NTFS_I(vi);
1818         ntfs_volume *vol = ni->vol;
1819         struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1820         struct page *cached_page = NULL;
1821         char __user *buf = NULL;
1822         s64 end, ll;
1823         VCN last_vcn;
1824         LCN lcn;
1825         unsigned long flags;
1826         size_t bytes, iov_ofs = 0;      /* Offset in the current iovec. */
1827         ssize_t status, written;
1828         unsigned nr_pages;
1829         int err;
1830         struct pagevec lru_pvec;
1831
1832         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
1833                         "pos 0x%llx, count 0x%lx.",
1834                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
1835                         (unsigned long long)pos, (unsigned long)count);
1836         if (unlikely(!count))
1837                 return 0;
1838         BUG_ON(NInoMstProtected(ni));
1839         /*
1840          * If the attribute is not an index root and it is encrypted or
1841          * compressed, we cannot write to it yet.  Note we need to check for
1842          * AT_INDEX_ALLOCATION since this is the type of both directory and
1843          * index inodes.
1844          */
1845         if (ni->type != AT_INDEX_ALLOCATION) {
1846                 /* If file is encrypted, deny access, just like NT4. */
1847                 if (NInoEncrypted(ni)) {
1848                         /*
1849                          * Reminder for later: Encrypted files are _always_
1850                          * non-resident so that the content can always be
1851                          * encrypted.
1852                          */
1853                         ntfs_debug("Denying write access to encrypted file.");
1854                         return -EACCES;
1855                 }
1856                 if (NInoCompressed(ni)) {
1857                         /* Only unnamed $DATA attribute can be compressed. */
1858                         BUG_ON(ni->type != AT_DATA);
1859                         BUG_ON(ni->name_len);
1860                         /*
1861                          * Reminder for later: If resident, the data is not
1862                          * actually compressed.  Only on the switch to non-
1863                          * resident does compression kick in.  This is in
1864                          * contrast to encrypted files (see above).
1865                          */
1866                         ntfs_error(vi->i_sb, "Writing to compressed files is "
1867                                         "not implemented yet.  Sorry.");
1868                         return -EOPNOTSUPP;
1869                 }
1870         }
1871         /*
1872          * If a previous ntfs_truncate() failed, repeat it and abort if it
1873          * fails again.
1874          */
1875         if (unlikely(NInoTruncateFailed(ni))) {
1876                 down_write(&vi->i_alloc_sem);
1877                 err = ntfs_truncate(vi);
1878                 up_write(&vi->i_alloc_sem);
1879                 if (err || NInoTruncateFailed(ni)) {
1880                         if (!err)
1881                                 err = -EIO;
1882                         ntfs_error(vol->sb, "Cannot perform write to inode "
1883                                         "0x%lx, attribute type 0x%x, because "
1884                                         "ntfs_truncate() failed (error code "
1885                                         "%i).", vi->i_ino,
1886                                         (unsigned)le32_to_cpu(ni->type), err);
1887                         return err;
1888                 }
1889         }
1890         /* The first byte after the write. */
1891         end = pos + count;
1892         /*
1893          * If the write goes beyond the allocated size, extend the allocation
1894          * to cover the whole of the write, rounded up to the nearest cluster.
1895          */
1896         read_lock_irqsave(&ni->size_lock, flags);
1897         ll = ni->allocated_size;
1898         read_unlock_irqrestore(&ni->size_lock, flags);
1899         if (end > ll) {
1900                 /* Extend the allocation without changing the data size. */
1901                 ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
1902                 if (likely(ll >= 0)) {
1903                         BUG_ON(pos >= ll);
1904                         /* If the extension was partial truncate the write. */
1905                         if (end > ll) {
1906                                 ntfs_debug("Truncating write to inode 0x%lx, "
1907                                                 "attribute type 0x%x, because "
1908                                                 "the allocation was only "
1909                                                 "partially extended.",
1910                                                 vi->i_ino, (unsigned)
1911                                                 le32_to_cpu(ni->type));
1912                                 end = ll;
1913                                 count = ll - pos;
1914                         }
1915                 } else {
1916                         err = ll;
1917                         read_lock_irqsave(&ni->size_lock, flags);
1918                         ll = ni->allocated_size;
1919                         read_unlock_irqrestore(&ni->size_lock, flags);
1920                         /* Perform a partial write if possible or fail. */
1921                         if (pos < ll) {
1922                                 ntfs_debug("Truncating write to inode 0x%lx, "
1923                                                 "attribute type 0x%x, because "
1924                                                 "extending the allocation "
1925                                                 "failed (error code %i).",
1926                                                 vi->i_ino, (unsigned)
1927                                                 le32_to_cpu(ni->type), err);
1928                                 end = ll;
1929                                 count = ll - pos;
1930                         } else {
1931                                 ntfs_error(vol->sb, "Cannot perform write to "
1932                                                 "inode 0x%lx, attribute type "
1933                                                 "0x%x, because extending the "
1934                                                 "allocation failed (error "
1935                                                 "code %i).", vi->i_ino,
1936                                                 (unsigned)
1937                                                 le32_to_cpu(ni->type), err);
1938                                 return err;
1939                         }
1940                 }
1941         }
1942         pagevec_init(&lru_pvec, 0);
1943         written = 0;
1944         /*
1945          * If the write starts beyond the initialized size, extend it up to the
1946          * beginning of the write and initialize all non-sparse space between
1947          * the old initialized size and the new one.  This automatically also
1948          * increments the vfs inode->i_size to keep it above or equal to the
1949          * initialized_size.
1950          */
1951         read_lock_irqsave(&ni->size_lock, flags);
1952         ll = ni->initialized_size;
1953         read_unlock_irqrestore(&ni->size_lock, flags);
1954         if (pos > ll) {
1955                 err = ntfs_attr_extend_initialized(ni, pos, &cached_page,
1956                                 &lru_pvec);
1957                 if (err < 0) {
1958                         ntfs_error(vol->sb, "Cannot perform write to inode "
1959                                         "0x%lx, attribute type 0x%x, because "
1960                                         "extending the initialized size "
1961                                         "failed (error code %i).", vi->i_ino,
1962                                         (unsigned)le32_to_cpu(ni->type), err);
1963                         status = err;
1964                         goto err_out;
1965                 }
1966         }
1967         /*
1968          * Determine the number of pages per cluster for non-resident
1969          * attributes.
1970          */
1971         nr_pages = 1;
1972         if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
1973                 nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
1974         /* Finally, perform the actual write. */
1975         last_vcn = -1;
1976         if (likely(nr_segs == 1))
1977                 buf = iov->iov_base;
1978         do {
1979                 VCN vcn;
1980                 pgoff_t idx, start_idx;
1981                 unsigned ofs, do_pages, u;
1982                 size_t copied;
1983
1984                 start_idx = idx = pos >> PAGE_CACHE_SHIFT;
1985                 ofs = pos & ~PAGE_CACHE_MASK;
1986                 bytes = PAGE_CACHE_SIZE - ofs;
1987                 do_pages = 1;
1988                 if (nr_pages > 1) {
1989                         vcn = pos >> vol->cluster_size_bits;
1990                         if (vcn != last_vcn) {
1991                                 last_vcn = vcn;
1992                                 /*
1993                                  * Get the lcn of the vcn the write is in.  If
1994                                  * it is a hole, need to lock down all pages in
1995                                  * the cluster.
1996                                  */
1997                                 down_read(&ni->runlist.lock);
1998                                 lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
1999                                                 vol->cluster_size_bits, false);
2000                                 up_read(&ni->runlist.lock);
2001                                 if (unlikely(lcn < LCN_HOLE)) {
2002                                         status = -EIO;
2003                                         if (lcn == LCN_ENOMEM)
2004                                                 status = -ENOMEM;
2005                                         else
2006                                                 ntfs_error(vol->sb, "Cannot "
2007                                                         "perform write to "
2008                                                         "inode 0x%lx, "
2009                                                         "attribute type 0x%x, "
2010                                                         "because the attribute "
2011                                                         "is corrupt.",
2012                                                         vi->i_ino, (unsigned)
2013                                                         le32_to_cpu(ni->type));
2014                                         break;
2015                                 }
2016                                 if (lcn == LCN_HOLE) {
2017                                         start_idx = (pos & ~(s64)
2018                                                         vol->cluster_size_mask)
2019                                                         >> PAGE_CACHE_SHIFT;
2020                                         bytes = vol->cluster_size - (pos &
2021                                                         vol->cluster_size_mask);
2022                                         do_pages = nr_pages;
2023                                 }
2024                         }
2025                 }
2026                 if (bytes > count)
2027                         bytes = count;
2028                 /*
2029                  * Bring in the user page(s) that we will copy from _first_.
2030                  * Otherwise there is a nasty deadlock on copying from the same
2031                  * page(s) as we are writing to, without it/them being marked
2032                  * up-to-date.  Note, at present there is nothing to stop the
2033                  * pages being swapped out between us bringing them into memory
2034                  * and doing the actual copying.
2035                  */
2036                 if (likely(nr_segs == 1))
2037                         ntfs_fault_in_pages_readable(buf, bytes);
2038                 else
2039                         ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
2040                 /* Get and lock @do_pages starting at index @start_idx. */
2041                 status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
2042                                 pages, &cached_page, &lru_pvec);
2043                 if (unlikely(status))
2044                         break;
2045                 /*
2046                  * For non-resident attributes, we need to fill any holes with
2047                  * actual clusters and ensure all bufferes are mapped.  We also
2048                  * need to bring uptodate any buffers that are only partially
2049                  * being written to.
2050                  */
2051                 if (NInoNonResident(ni)) {
2052                         status = ntfs_prepare_pages_for_non_resident_write(
2053                                         pages, do_pages, pos, bytes);
2054                         if (unlikely(status)) {
2055                                 loff_t i_size;
2056
2057                                 do {
2058                                         unlock_page(pages[--do_pages]);
2059                                         page_cache_release(pages[do_pages]);
2060                                 } while (do_pages);
2061                                 /*
2062                                  * The write preparation may have instantiated
2063                                  * allocated space outside i_size.  Trim this
2064                                  * off again.  We can ignore any errors in this
2065                                  * case as we will just be waisting a bit of
2066                                  * allocated space, which is not a disaster.
2067                                  */
2068                                 i_size = i_size_read(vi);
2069                                 if (pos + bytes > i_size)
2070                                         vmtruncate(vi, i_size);
2071                                 break;
2072                         }
2073                 }
2074                 u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
2075                 if (likely(nr_segs == 1)) {
2076                         copied = ntfs_copy_from_user(pages + u, do_pages - u,
2077                                         ofs, buf, bytes);
2078                         buf += copied;
2079                 } else
2080                         copied = ntfs_copy_from_user_iovec(pages + u,
2081                                         do_pages - u, ofs, &iov, &iov_ofs,
2082                                         bytes);
2083                 ntfs_flush_dcache_pages(pages + u, do_pages - u);
2084                 status = ntfs_commit_pages_after_write(pages, do_pages, pos,
2085                                 bytes);
2086                 if (likely(!status)) {
2087                         written += copied;
2088                         count -= copied;
2089                         pos += copied;
2090                         if (unlikely(copied != bytes))
2091                                 status = -EFAULT;
2092                 }
2093                 do {
2094                         unlock_page(pages[--do_pages]);
2095                         mark_page_accessed(pages[do_pages]);
2096                         page_cache_release(pages[do_pages]);
2097                 } while (do_pages);
2098                 if (unlikely(status))
2099                         break;
2100                 balance_dirty_pages_ratelimited(mapping);
2101                 cond_resched();
2102         } while (count);
2103 err_out:
2104         *ppos = pos;
2105         if (cached_page)
2106                 page_cache_release(cached_page);
2107         /* For now, when the user asks for O_SYNC, we actually give O_DSYNC. */
2108         if (likely(!status)) {
2109                 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(vi))) {
2110                         if (!mapping->a_ops->writepage || !is_sync_kiocb(iocb))
2111                                 status = generic_osync_inode(vi, mapping,
2112                                                 OSYNC_METADATA|OSYNC_DATA);
2113                 }
2114         }
2115         pagevec_lru_add(&lru_pvec);
2116         ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
2117                         written ? "written" : "status", (unsigned long)written,
2118                         (long)status);
2119         return written ? written : status;
2120 }
2121
2122 /**
2123  * ntfs_file_aio_write_nolock -
2124  */
2125 static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
2126                 const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
2127 {
2128         struct file *file = iocb->ki_filp;
2129         struct address_space *mapping = file->f_mapping;
2130         struct inode *inode = mapping->host;
2131         loff_t pos;
2132         unsigned long seg;
2133         size_t count;           /* after file limit checks */
2134         ssize_t written, err;
2135
2136         count = 0;
2137         for (seg = 0; seg < nr_segs; seg++) {
2138                 const struct iovec *iv = &iov[seg];
2139                 /*
2140                  * If any segment has a negative length, or the cumulative
2141                  * length ever wraps negative then return -EINVAL.
2142                  */
2143                 count += iv->iov_len;
2144                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
2145                         return -EINVAL;
2146                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2147                         continue;
2148                 if (!seg)
2149                         return -EFAULT;
2150                 nr_segs = seg;
2151                 count -= iv->iov_len;   /* This segment is no good */
2152                 break;
2153         }
2154         pos = *ppos;
2155         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2156         /* We can write back this queue in page reclaim. */
2157         current->backing_dev_info = mapping->backing_dev_info;
2158         written = 0;
2159         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2160         if (err)
2161                 goto out;
2162         if (!count)
2163                 goto out;
2164         err = remove_suid(file->f_path.dentry);
2165         if (err)
2166                 goto out;
2167         file_update_time(file);
2168         written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
2169                         count);
2170 out:
2171         current->backing_dev_info = NULL;
2172         return written ? written : err;
2173 }
2174
2175 /**
2176  * ntfs_file_aio_write -
2177  */
2178 static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2179                 unsigned long nr_segs, loff_t pos)
2180 {
2181         struct file *file = iocb->ki_filp;
2182         struct address_space *mapping = file->f_mapping;
2183         struct inode *inode = mapping->host;
2184         ssize_t ret;
2185
2186         BUG_ON(iocb->ki_pos != pos);
2187
2188         mutex_lock(&inode->i_mutex);
2189         ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
2190         mutex_unlock(&inode->i_mutex);
2191         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2192                 int err = sync_page_range(inode, mapping, pos, ret);
2193                 if (err < 0)
2194                         ret = err;
2195         }
2196         return ret;
2197 }
2198
2199 /**
2200  * ntfs_file_writev -
2201  *
2202  * Basically the same as generic_file_writev() except that it ends up calling
2203  * ntfs_file_aio_write_nolock() instead of __generic_file_aio_write_nolock().
2204  */
2205 static ssize_t ntfs_file_writev(struct file *file, const struct iovec *iov,
2206                 unsigned long nr_segs, loff_t *ppos)
2207 {
2208         struct address_space *mapping = file->f_mapping;
2209         struct inode *inode = mapping->host;
2210         struct kiocb kiocb;
2211         ssize_t ret;
2212
2213         mutex_lock(&inode->i_mutex);
2214         init_sync_kiocb(&kiocb, file);
2215         ret = ntfs_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2216         if (ret == -EIOCBQUEUED)
2217                 ret = wait_on_sync_kiocb(&kiocb);
2218         mutex_unlock(&inode->i_mutex);
2219         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2220                 int err = sync_page_range(inode, mapping, *ppos - ret, ret);
2221                 if (err < 0)
2222                         ret = err;
2223         }
2224         return ret;
2225 }
2226
2227 /**
2228  * ntfs_file_write - simple wrapper for ntfs_file_writev()
2229  */
2230 static ssize_t ntfs_file_write(struct file *file, const char __user *buf,
2231                 size_t count, loff_t *ppos)
2232 {
2233         struct iovec local_iov = { .iov_base = (void __user *)buf,
2234                                    .iov_len = count };
2235
2236         return ntfs_file_writev(file, &local_iov, 1, ppos);
2237 }
2238
2239 /**
2240  * ntfs_file_fsync - sync a file to disk
2241  * @filp:       file to be synced
2242  * @dentry:     dentry describing the file to sync
2243  * @datasync:   if non-zero only flush user data and not metadata
2244  *
2245  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
2246  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
2247  *
2248  * If @datasync is false, write the mft record and all associated extent mft
2249  * records as well as the $DATA attribute and then sync the block device.
2250  *
2251  * If @datasync is true and the attribute is non-resident, we skip the writing
2252  * of the mft record and all associated extent mft records (this might still
2253  * happen due to the write_inode_now() call).
2254  *
2255  * Also, if @datasync is true, we do not wait on the inode to be written out
2256  * but we always wait on the page cache pages to be written out.
2257  *
2258  * Note: In the past @filp could be NULL so we ignore it as we don't need it
2259  * anyway.
2260  *
2261  * Locking: Caller must hold i_mutex on the inode.
2262  *
2263  * TODO: We should probably also write all attribute/index inodes associated
2264  * with this inode but since we have no simple way of getting to them we ignore
2265  * this problem for now.
2266  */
2267 static int ntfs_file_fsync(struct file *filp, struct dentry *dentry,
2268                 int datasync)
2269 {
2270         struct inode *vi = dentry->d_inode;
2271         int err, ret = 0;
2272
2273         ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
2274         BUG_ON(S_ISDIR(vi->i_mode));
2275         if (!datasync || !NInoNonResident(NTFS_I(vi)))
2276                 ret = ntfs_write_inode(vi, 1);
2277         write_inode_now(vi, !datasync);
2278         /*
2279          * NOTE: If we were to use mapping->private_list (see ext2 and
2280          * fs/buffer.c) for dirty blocks then we could optimize the below to be
2281          * sync_mapping_buffers(vi->i_mapping).
2282          */
2283         err = sync_blockdev(vi->i_sb->s_bdev);
2284         if (unlikely(err && !ret))
2285                 ret = err;
2286         if (likely(!ret))
2287                 ntfs_debug("Done.");
2288         else
2289                 ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
2290                                 "%u.", datasync ? "data" : "", vi->i_ino, -ret);
2291         return ret;
2292 }
2293
2294 #endif /* NTFS_RW */
2295
2296 const struct file_operations ntfs_file_ops = {
2297         .llseek         = generic_file_llseek,   /* Seek inside file. */
2298         .read           = do_sync_read,          /* Read from file. */
2299         .aio_read       = generic_file_aio_read, /* Async read from file. */
2300 #ifdef NTFS_RW
2301         .write          = ntfs_file_write,       /* Write to file. */
2302         .aio_write      = ntfs_file_aio_write,   /* Async write to file. */
2303         /*.release      = ,*/                    /* Last file is closed.  See
2304                                                     fs/ext2/file.c::
2305                                                     ext2_release_file() for
2306                                                     how to use this to discard
2307                                                     preallocated space for
2308                                                     write opened files. */
2309         .fsync          = ntfs_file_fsync,       /* Sync a file to disk. */
2310         /*.aio_fsync    = ,*/                    /* Sync all outstanding async
2311                                                     i/o operations on a
2312                                                     kiocb. */
2313 #endif /* NTFS_RW */
2314         /*.ioctl        = ,*/                    /* Perform function on the
2315                                                     mounted filesystem. */
2316         .mmap           = generic_file_mmap,     /* Mmap file. */
2317         .open           = ntfs_file_open,        /* Open file. */
2318         .sendfile       = generic_file_sendfile, /* Zero-copy data send with
2319                                                     the data source being on
2320                                                     the ntfs partition.  We do
2321                                                     not need to care about the
2322                                                     data destination. */
2323         /*.sendpage     = ,*/                    /* Zero-copy data send with
2324                                                     the data destination being
2325                                                     on the ntfs partition.  We
2326                                                     do not need to care about
2327                                                     the data source. */
2328 };
2329
2330 const struct inode_operations ntfs_file_inode_ops = {
2331 #ifdef NTFS_RW
2332         .truncate       = ntfs_truncate_vfs,
2333         .setattr        = ntfs_setattr,
2334 #endif /* NTFS_RW */
2335 };
2336
2337 const struct file_operations ntfs_empty_file_ops = {};
2338
2339 const struct inode_operations ntfs_empty_inode_ops = {};