xref: /openbmc/linux/fs/ntfs/file.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
3  *
4  * Copyright (c) 2001-2005 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_sem 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_cache_page(mapping, index,
235 				(filler_t*)mapping->a_ops->readpage, NULL);
236 		if (IS_ERR(page)) {
237 			err = PTR_ERR(page);
238 			goto init_err_out;
239 		}
240 		wait_on_page_locked(page);
241 		if (unlikely(!PageUptodate(page) || PageError(page))) {
242 			page_cache_release(page);
243 			err = -EIO;
244 			goto init_err_out;
245 		}
246 		/*
247 		 * Update the initialized size in the ntfs inode.  This is
248 		 * enough to make ntfs_writepage() work.
249 		 */
250 		write_lock_irqsave(&ni->size_lock, flags);
251 		ni->initialized_size = (index + 1) << PAGE_CACHE_SHIFT;
252 		if (ni->initialized_size > new_init_size)
253 			ni->initialized_size = new_init_size;
254 		write_unlock_irqrestore(&ni->size_lock, flags);
255 		/* Set the page dirty so it gets written out. */
256 		set_page_dirty(page);
257 		page_cache_release(page);
258 		/*
259 		 * Play nice with the vm and the rest of the system.  This is
260 		 * very much needed as we can potentially be modifying the
261 		 * initialised size from a very small value to a really huge
262 		 * value, e.g.
263 		 *	f = open(somefile, O_TRUNC);
264 		 *	truncate(f, 10GiB);
265 		 *	seek(f, 10GiB);
266 		 *	write(f, 1);
267 		 * And this would mean we would be marking dirty hundreds of
268 		 * thousands of pages or as in the above example more than
269 		 * two and a half million pages!
270 		 *
271 		 * TODO: For sparse pages could optimize this workload by using
272 		 * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
273 		 * would be set in readpage for sparse pages and here we would
274 		 * not need to mark dirty any pages which have this bit set.
275 		 * The only caveat is that we have to clear the bit everywhere
276 		 * where we allocate any clusters that lie in the page or that
277 		 * contain the page.
278 		 *
279 		 * TODO: An even greater optimization would be for us to only
280 		 * call readpage() on pages which are not in sparse regions as
281 		 * determined from the runlist.  This would greatly reduce the
282 		 * number of pages we read and make dirty in the case of sparse
283 		 * files.
284 		 */
285 		balance_dirty_pages_ratelimited(mapping);
286 		cond_resched();
287 	} while (++index < end_index);
288 	read_lock_irqsave(&ni->size_lock, flags);
289 	BUG_ON(ni->initialized_size != new_init_size);
290 	read_unlock_irqrestore(&ni->size_lock, flags);
291 	/* Now bring in sync the initialized_size in the mft record. */
292 	m = map_mft_record(base_ni);
293 	if (IS_ERR(m)) {
294 		err = PTR_ERR(m);
295 		m = NULL;
296 		goto init_err_out;
297 	}
298 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
299 	if (unlikely(!ctx)) {
300 		err = -ENOMEM;
301 		goto init_err_out;
302 	}
303 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
304 			CASE_SENSITIVE, 0, NULL, 0, ctx);
305 	if (unlikely(err)) {
306 		if (err == -ENOENT)
307 			err = -EIO;
308 		goto init_err_out;
309 	}
310 	m = ctx->mrec;
311 	a = ctx->attr;
312 	BUG_ON(!a->non_resident);
313 	a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
314 done:
315 	flush_dcache_mft_record_page(ctx->ntfs_ino);
316 	mark_mft_record_dirty(ctx->ntfs_ino);
317 	if (ctx)
318 		ntfs_attr_put_search_ctx(ctx);
319 	if (m)
320 		unmap_mft_record(base_ni);
321 	ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
322 			(unsigned long long)new_init_size, i_size_read(vi));
323 	return 0;
324 init_err_out:
325 	write_lock_irqsave(&ni->size_lock, flags);
326 	ni->initialized_size = old_init_size;
327 	write_unlock_irqrestore(&ni->size_lock, flags);
328 err_out:
329 	if (ctx)
330 		ntfs_attr_put_search_ctx(ctx);
331 	if (m)
332 		unmap_mft_record(base_ni);
333 	ntfs_debug("Failed.  Returning error code %i.", err);
334 	return err;
335 }
336 
337 /**
338  * ntfs_fault_in_pages_readable -
339  *
340  * Fault a number of userspace pages into pagetables.
341  *
342  * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
343  * with more than two userspace pages as well as handling the single page case
344  * elegantly.
345  *
346  * If you find this difficult to understand, then think of the while loop being
347  * the following code, except that we do without the integer variable ret:
348  *
349  *	do {
350  *		ret = __get_user(c, uaddr);
351  *		uaddr += PAGE_SIZE;
352  *	} while (!ret && uaddr < end);
353  *
354  * Note, the final __get_user() may well run out-of-bounds of the user buffer,
355  * but _not_ out-of-bounds of the page the user buffer belongs to, and since
356  * this is only a read and not a write, and since it is still in the same page,
357  * it should not matter and this makes the code much simpler.
358  */
359 static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
360 		int bytes)
361 {
362 	const char __user *end;
363 	volatile char c;
364 
365 	/* Set @end to the first byte outside the last page we care about. */
366 	end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
367 
368 	while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
369 		;
370 }
371 
372 /**
373  * ntfs_fault_in_pages_readable_iovec -
374  *
375  * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
376  */
377 static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
378 		size_t iov_ofs, int bytes)
379 {
380 	do {
381 		const char __user *buf;
382 		unsigned len;
383 
384 		buf = iov->iov_base + iov_ofs;
385 		len = iov->iov_len - iov_ofs;
386 		if (len > bytes)
387 			len = bytes;
388 		ntfs_fault_in_pages_readable(buf, len);
389 		bytes -= len;
390 		iov++;
391 		iov_ofs = 0;
392 	} while (bytes);
393 }
394 
395 /**
396  * __ntfs_grab_cache_pages - obtain a number of locked pages
397  * @mapping:	address space mapping from which to obtain page cache pages
398  * @index:	starting index in @mapping at which to begin obtaining pages
399  * @nr_pages:	number of page cache pages to obtain
400  * @pages:	array of pages in which to return the obtained page cache pages
401  * @cached_page: allocated but as yet unused page
402  * @lru_pvec:	lru-buffering pagevec of caller
403  *
404  * Obtain @nr_pages locked page cache pages from the mapping @maping and
405  * starting at index @index.
406  *
407  * If a page is newly created, increment its refcount and add it to the
408  * caller's lru-buffering pagevec @lru_pvec.
409  *
410  * This is the same as mm/filemap.c::__grab_cache_page(), except that @nr_pages
411  * are obtained at once instead of just one page and that 0 is returned on
412  * success and -errno on error.
413  *
414  * Note, the page locks are obtained in ascending page index order.
415  */
416 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
417 		pgoff_t index, const unsigned nr_pages, struct page **pages,
418 		struct page **cached_page, struct pagevec *lru_pvec)
419 {
420 	int err, nr;
421 
422 	BUG_ON(!nr_pages);
423 	err = nr = 0;
424 	do {
425 		pages[nr] = find_lock_page(mapping, index);
426 		if (!pages[nr]) {
427 			if (!*cached_page) {
428 				*cached_page = page_cache_alloc(mapping);
429 				if (unlikely(!*cached_page)) {
430 					err = -ENOMEM;
431 					goto err_out;
432 				}
433 			}
434 			err = add_to_page_cache(*cached_page, mapping, index,
435 					GFP_KERNEL);
436 			if (unlikely(err)) {
437 				if (err == -EEXIST)
438 					continue;
439 				goto err_out;
440 			}
441 			pages[nr] = *cached_page;
442 			page_cache_get(*cached_page);
443 			if (unlikely(!pagevec_add(lru_pvec, *cached_page)))
444 				__pagevec_lru_add(lru_pvec);
445 			*cached_page = NULL;
446 		}
447 		index++;
448 		nr++;
449 	} while (nr < nr_pages);
450 out:
451 	return err;
452 err_out:
453 	while (nr > 0) {
454 		unlock_page(pages[--nr]);
455 		page_cache_release(pages[nr]);
456 	}
457 	goto out;
458 }
459 
460 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
461 {
462 	lock_buffer(bh);
463 	get_bh(bh);
464 	bh->b_end_io = end_buffer_read_sync;
465 	return submit_bh(READ, bh);
466 }
467 
468 /**
469  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
470  * @pages:	array of destination pages
471  * @nr_pages:	number of pages in @pages
472  * @pos:	byte position in file at which the write begins
473  * @bytes:	number of bytes to be written
474  *
475  * This is called for non-resident attributes from ntfs_file_buffered_write()
476  * with i_sem held on the inode (@pages[0]->mapping->host).  There are
477  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
478  * data has not yet been copied into the @pages.
479  *
480  * Need to fill any holes with actual clusters, allocate buffers if necessary,
481  * ensure all the buffers are mapped, and bring uptodate any buffers that are
482  * only partially being written to.
483  *
484  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
485  * greater than PAGE_CACHE_SIZE, that all pages in @pages are entirely inside
486  * the same cluster and that they are the entirety of that cluster, and that
487  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
488  *
489  * i_size is not to be modified yet.
490  *
491  * Return 0 on success or -errno on error.
492  */
493 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
494 		unsigned nr_pages, s64 pos, size_t bytes)
495 {
496 	VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
497 	LCN lcn;
498 	s64 bh_pos, vcn_len, end, initialized_size;
499 	sector_t lcn_block;
500 	struct page *page;
501 	struct inode *vi;
502 	ntfs_inode *ni, *base_ni = NULL;
503 	ntfs_volume *vol;
504 	runlist_element *rl, *rl2;
505 	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
506 	ntfs_attr_search_ctx *ctx = NULL;
507 	MFT_RECORD *m = NULL;
508 	ATTR_RECORD *a = NULL;
509 	unsigned long flags;
510 	u32 attr_rec_len = 0;
511 	unsigned blocksize, u;
512 	int err, mp_size;
513 	BOOL rl_write_locked, was_hole, is_retry;
514 	unsigned char blocksize_bits;
515 	struct {
516 		u8 runlist_merged:1;
517 		u8 mft_attr_mapped:1;
518 		u8 mp_rebuilt:1;
519 		u8 attr_switched:1;
520 	} status = { 0, 0, 0, 0 };
521 
522 	BUG_ON(!nr_pages);
523 	BUG_ON(!pages);
524 	BUG_ON(!*pages);
525 	vi = pages[0]->mapping->host;
526 	ni = NTFS_I(vi);
527 	vol = ni->vol;
528 	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
529 			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
530 			vi->i_ino, ni->type, pages[0]->index, nr_pages,
531 			(long long)pos, bytes);
532 	blocksize_bits = vi->i_blkbits;
533 	blocksize = 1 << blocksize_bits;
534 	u = 0;
535 	do {
536 		struct page *page = pages[u];
537 		/*
538 		 * create_empty_buffers() will create uptodate/dirty buffers if
539 		 * the page is uptodate/dirty.
540 		 */
541 		if (!page_has_buffers(page)) {
542 			create_empty_buffers(page, blocksize, 0);
543 			if (unlikely(!page_has_buffers(page)))
544 				return -ENOMEM;
545 		}
546 	} while (++u < nr_pages);
547 	rl_write_locked = FALSE;
548 	rl = NULL;
549 	err = 0;
550 	vcn = lcn = -1;
551 	vcn_len = 0;
552 	lcn_block = -1;
553 	was_hole = FALSE;
554 	cpos = pos >> vol->cluster_size_bits;
555 	end = pos + bytes;
556 	cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
557 	/*
558 	 * Loop over each page and for each page over each buffer.  Use goto to
559 	 * reduce indentation.
560 	 */
561 	u = 0;
562 do_next_page:
563 	page = pages[u];
564 	bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
565 	bh = head = page_buffers(page);
566 	do {
567 		VCN cdelta;
568 		s64 bh_end;
569 		unsigned bh_cofs;
570 
571 		/* Clear buffer_new on all buffers to reinitialise state. */
572 		if (buffer_new(bh))
573 			clear_buffer_new(bh);
574 		bh_end = bh_pos + blocksize;
575 		bh_cpos = bh_pos >> vol->cluster_size_bits;
576 		bh_cofs = bh_pos & vol->cluster_size_mask;
577 		if (buffer_mapped(bh)) {
578 			/*
579 			 * The buffer is already mapped.  If it is uptodate,
580 			 * ignore it.
581 			 */
582 			if (buffer_uptodate(bh))
583 				continue;
584 			/*
585 			 * The buffer is not uptodate.  If the page is uptodate
586 			 * set the buffer uptodate and otherwise ignore it.
587 			 */
588 			if (PageUptodate(page)) {
589 				set_buffer_uptodate(bh);
590 				continue;
591 			}
592 			/*
593 			 * Neither the page nor the buffer are uptodate.  If
594 			 * the buffer is only partially being written to, we
595 			 * need to read it in before the write, i.e. now.
596 			 */
597 			if ((bh_pos < pos && bh_end > pos) ||
598 					(bh_pos < end && bh_end > end)) {
599 				/*
600 				 * If the buffer is fully or partially within
601 				 * the initialized size, do an actual read.
602 				 * Otherwise, simply zero the buffer.
603 				 */
604 				read_lock_irqsave(&ni->size_lock, flags);
605 				initialized_size = ni->initialized_size;
606 				read_unlock_irqrestore(&ni->size_lock, flags);
607 				if (bh_pos < initialized_size) {
608 					ntfs_submit_bh_for_read(bh);
609 					*wait_bh++ = bh;
610 				} else {
611 					u8 *kaddr = kmap_atomic(page, KM_USER0);
612 					memset(kaddr + bh_offset(bh), 0,
613 							blocksize);
614 					kunmap_atomic(kaddr, KM_USER0);
615 					flush_dcache_page(page);
616 					set_buffer_uptodate(bh);
617 				}
618 			}
619 			continue;
620 		}
621 		/* Unmapped buffer.  Need to map it. */
622 		bh->b_bdev = vol->sb->s_bdev;
623 		/*
624 		 * If the current buffer is in the same clusters as the map
625 		 * cache, there is no need to check the runlist again.  The
626 		 * map cache is made up of @vcn, which is the first cached file
627 		 * cluster, @vcn_len which is the number of cached file
628 		 * clusters, @lcn is the device cluster corresponding to @vcn,
629 		 * and @lcn_block is the block number corresponding to @lcn.
630 		 */
631 		cdelta = bh_cpos - vcn;
632 		if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
633 map_buffer_cached:
634 			BUG_ON(lcn < 0);
635 			bh->b_blocknr = lcn_block +
636 					(cdelta << (vol->cluster_size_bits -
637 					blocksize_bits)) +
638 					(bh_cofs >> blocksize_bits);
639 			set_buffer_mapped(bh);
640 			/*
641 			 * If the page is uptodate so is the buffer.  If the
642 			 * buffer is fully outside the write, we ignore it if
643 			 * it was already allocated and we mark it dirty so it
644 			 * gets written out if we allocated it.  On the other
645 			 * hand, if we allocated the buffer but we are not
646 			 * marking it dirty we set buffer_new so we can do
647 			 * error recovery.
648 			 */
649 			if (PageUptodate(page)) {
650 				if (!buffer_uptodate(bh))
651 					set_buffer_uptodate(bh);
652 				if (unlikely(was_hole)) {
653 					/* We allocated the buffer. */
654 					unmap_underlying_metadata(bh->b_bdev,
655 							bh->b_blocknr);
656 					if (bh_end <= pos || bh_pos >= end)
657 						mark_buffer_dirty(bh);
658 					else
659 						set_buffer_new(bh);
660 				}
661 				continue;
662 			}
663 			/* Page is _not_ uptodate. */
664 			if (likely(!was_hole)) {
665 				/*
666 				 * Buffer was already allocated.  If it is not
667 				 * uptodate and is only partially being written
668 				 * to, we need to read it in before the write,
669 				 * i.e. now.
670 				 */
671 				if (!buffer_uptodate(bh) && bh_pos < end &&
672 						bh_end > pos &&
673 						(bh_pos < pos ||
674 						bh_end > end)) {
675 					/*
676 					 * If the buffer is fully or partially
677 					 * within the initialized size, do an
678 					 * actual read.  Otherwise, simply zero
679 					 * the buffer.
680 					 */
681 					read_lock_irqsave(&ni->size_lock,
682 							flags);
683 					initialized_size = ni->initialized_size;
684 					read_unlock_irqrestore(&ni->size_lock,
685 							flags);
686 					if (bh_pos < initialized_size) {
687 						ntfs_submit_bh_for_read(bh);
688 						*wait_bh++ = bh;
689 					} else {
690 						u8 *kaddr = kmap_atomic(page,
691 								KM_USER0);
692 						memset(kaddr + bh_offset(bh),
693 								0, blocksize);
694 						kunmap_atomic(kaddr, KM_USER0);
695 						flush_dcache_page(page);
696 						set_buffer_uptodate(bh);
697 					}
698 				}
699 				continue;
700 			}
701 			/* We allocated the buffer. */
702 			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
703 			/*
704 			 * If the buffer is fully outside the write, zero it,
705 			 * set it uptodate, and mark it dirty so it gets
706 			 * written out.  If it is partially being written to,
707 			 * zero region surrounding the write but leave it to
708 			 * commit write to do anything else.  Finally, if the
709 			 * buffer is fully being overwritten, do nothing.
710 			 */
711 			if (bh_end <= pos || bh_pos >= end) {
712 				if (!buffer_uptodate(bh)) {
713 					u8 *kaddr = kmap_atomic(page, KM_USER0);
714 					memset(kaddr + bh_offset(bh), 0,
715 							blocksize);
716 					kunmap_atomic(kaddr, KM_USER0);
717 					flush_dcache_page(page);
718 					set_buffer_uptodate(bh);
719 				}
720 				mark_buffer_dirty(bh);
721 				continue;
722 			}
723 			set_buffer_new(bh);
724 			if (!buffer_uptodate(bh) &&
725 					(bh_pos < pos || bh_end > end)) {
726 				u8 *kaddr;
727 				unsigned pofs;
728 
729 				kaddr = kmap_atomic(page, KM_USER0);
730 				if (bh_pos < pos) {
731 					pofs = bh_pos & ~PAGE_CACHE_MASK;
732 					memset(kaddr + pofs, 0, pos - bh_pos);
733 				}
734 				if (bh_end > end) {
735 					pofs = end & ~PAGE_CACHE_MASK;
736 					memset(kaddr + pofs, 0, bh_end - end);
737 				}
738 				kunmap_atomic(kaddr, KM_USER0);
739 				flush_dcache_page(page);
740 			}
741 			continue;
742 		}
743 		/*
744 		 * Slow path: this is the first buffer in the cluster.  If it
745 		 * is outside allocated size and is not uptodate, zero it and
746 		 * set it uptodate.
747 		 */
748 		read_lock_irqsave(&ni->size_lock, flags);
749 		initialized_size = ni->allocated_size;
750 		read_unlock_irqrestore(&ni->size_lock, flags);
751 		if (bh_pos > initialized_size) {
752 			if (PageUptodate(page)) {
753 				if (!buffer_uptodate(bh))
754 					set_buffer_uptodate(bh);
755 			} else if (!buffer_uptodate(bh)) {
756 				u8 *kaddr = kmap_atomic(page, KM_USER0);
757 				memset(kaddr + bh_offset(bh), 0, blocksize);
758 				kunmap_atomic(kaddr, KM_USER0);
759 				flush_dcache_page(page);
760 				set_buffer_uptodate(bh);
761 			}
762 			continue;
763 		}
764 		is_retry = FALSE;
765 		if (!rl) {
766 			down_read(&ni->runlist.lock);
767 retry_remap:
768 			rl = ni->runlist.rl;
769 		}
770 		if (likely(rl != NULL)) {
771 			/* Seek to element containing target cluster. */
772 			while (rl->length && rl[1].vcn <= bh_cpos)
773 				rl++;
774 			lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
775 			if (likely(lcn >= 0)) {
776 				/*
777 				 * Successful remap, setup the map cache and
778 				 * use that to deal with the buffer.
779 				 */
780 				was_hole = FALSE;
781 				vcn = bh_cpos;
782 				vcn_len = rl[1].vcn - vcn;
783 				lcn_block = lcn << (vol->cluster_size_bits -
784 						blocksize_bits);
785 				cdelta = 0;
786 				/*
787 				 * If the number of remaining clusters touched
788 				 * by the write is smaller or equal to the
789 				 * number of cached clusters, unlock the
790 				 * runlist as the map cache will be used from
791 				 * now on.
792 				 */
793 				if (likely(vcn + vcn_len >= cend)) {
794 					if (rl_write_locked) {
795 						up_write(&ni->runlist.lock);
796 						rl_write_locked = FALSE;
797 					} else
798 						up_read(&ni->runlist.lock);
799 					rl = NULL;
800 				}
801 				goto map_buffer_cached;
802 			}
803 		} else
804 			lcn = LCN_RL_NOT_MAPPED;
805 		/*
806 		 * If it is not a hole and not out of bounds, the runlist is
807 		 * probably unmapped so try to map it now.
808 		 */
809 		if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
810 			if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
811 				/* Attempt to map runlist. */
812 				if (!rl_write_locked) {
813 					/*
814 					 * We need the runlist locked for
815 					 * writing, so if it is locked for
816 					 * reading relock it now and retry in
817 					 * case it changed whilst we dropped
818 					 * the lock.
819 					 */
820 					up_read(&ni->runlist.lock);
821 					down_write(&ni->runlist.lock);
822 					rl_write_locked = TRUE;
823 					goto retry_remap;
824 				}
825 				err = ntfs_map_runlist_nolock(ni, bh_cpos,
826 						NULL);
827 				if (likely(!err)) {
828 					is_retry = TRUE;
829 					goto retry_remap;
830 				}
831 				/*
832 				 * If @vcn is out of bounds, pretend @lcn is
833 				 * LCN_ENOENT.  As long as the buffer is out
834 				 * of bounds this will work fine.
835 				 */
836 				if (err == -ENOENT) {
837 					lcn = LCN_ENOENT;
838 					err = 0;
839 					goto rl_not_mapped_enoent;
840 				}
841 			} else
842 				err = -EIO;
843 			/* Failed to map the buffer, even after retrying. */
844 			bh->b_blocknr = -1;
845 			ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
846 					"attribute type 0x%x, vcn 0x%llx, "
847 					"vcn offset 0x%x, because its "
848 					"location on disk could not be "
849 					"determined%s (error code %i).",
850 					ni->mft_no, ni->type,
851 					(unsigned long long)bh_cpos,
852 					(unsigned)bh_pos &
853 					vol->cluster_size_mask,
854 					is_retry ? " even after retrying" : "",
855 					err);
856 			break;
857 		}
858 rl_not_mapped_enoent:
859 		/*
860 		 * The buffer is in a hole or out of bounds.  We need to fill
861 		 * the hole, unless the buffer is in a cluster which is not
862 		 * touched by the write, in which case we just leave the buffer
863 		 * unmapped.  This can only happen when the cluster size is
864 		 * less than the page cache size.
865 		 */
866 		if (unlikely(vol->cluster_size < PAGE_CACHE_SIZE)) {
867 			bh_cend = (bh_end + vol->cluster_size - 1) >>
868 					vol->cluster_size_bits;
869 			if ((bh_cend <= cpos || bh_cpos >= cend)) {
870 				bh->b_blocknr = -1;
871 				/*
872 				 * If the buffer is uptodate we skip it.  If it
873 				 * is not but the page is uptodate, we can set
874 				 * the buffer uptodate.  If the page is not
875 				 * uptodate, we can clear the buffer and set it
876 				 * uptodate.  Whether this is worthwhile is
877 				 * debatable and this could be removed.
878 				 */
879 				if (PageUptodate(page)) {
880 					if (!buffer_uptodate(bh))
881 						set_buffer_uptodate(bh);
882 				} else if (!buffer_uptodate(bh)) {
883 					u8 *kaddr = kmap_atomic(page, KM_USER0);
884 					memset(kaddr + bh_offset(bh), 0,
885 							blocksize);
886 					kunmap_atomic(kaddr, KM_USER0);
887 					flush_dcache_page(page);
888 					set_buffer_uptodate(bh);
889 				}
890 				continue;
891 			}
892 		}
893 		/*
894 		 * Out of bounds buffer is invalid if it was not really out of
895 		 * bounds.
896 		 */
897 		BUG_ON(lcn != LCN_HOLE);
898 		/*
899 		 * We need the runlist locked for writing, so if it is locked
900 		 * for reading relock it now and retry in case it changed
901 		 * whilst we dropped the lock.
902 		 */
903 		BUG_ON(!rl);
904 		if (!rl_write_locked) {
905 			up_read(&ni->runlist.lock);
906 			down_write(&ni->runlist.lock);
907 			rl_write_locked = TRUE;
908 			goto retry_remap;
909 		}
910 		/* Find the previous last allocated cluster. */
911 		BUG_ON(rl->lcn != LCN_HOLE);
912 		lcn = -1;
913 		rl2 = rl;
914 		while (--rl2 >= ni->runlist.rl) {
915 			if (rl2->lcn >= 0) {
916 				lcn = rl2->lcn + rl2->length;
917 				break;
918 			}
919 		}
920 		rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
921 				FALSE);
922 		if (IS_ERR(rl2)) {
923 			err = PTR_ERR(rl2);
924 			ntfs_debug("Failed to allocate cluster, error code %i.",
925 					err);
926 			break;
927 		}
928 		lcn = rl2->lcn;
929 		rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
930 		if (IS_ERR(rl)) {
931 			err = PTR_ERR(rl);
932 			if (err != -ENOMEM)
933 				err = -EIO;
934 			if (ntfs_cluster_free_from_rl(vol, rl2)) {
935 				ntfs_error(vol->sb, "Failed to release "
936 						"allocated cluster in error "
937 						"code path.  Run chkdsk to "
938 						"recover the lost cluster.");
939 				NVolSetErrors(vol);
940 			}
941 			ntfs_free(rl2);
942 			break;
943 		}
944 		ni->runlist.rl = rl;
945 		status.runlist_merged = 1;
946 		ntfs_debug("Allocated cluster, lcn 0x%llx.", lcn);
947 		/* Map and lock the mft record and get the attribute record. */
948 		if (!NInoAttr(ni))
949 			base_ni = ni;
950 		else
951 			base_ni = ni->ext.base_ntfs_ino;
952 		m = map_mft_record(base_ni);
953 		if (IS_ERR(m)) {
954 			err = PTR_ERR(m);
955 			break;
956 		}
957 		ctx = ntfs_attr_get_search_ctx(base_ni, m);
958 		if (unlikely(!ctx)) {
959 			err = -ENOMEM;
960 			unmap_mft_record(base_ni);
961 			break;
962 		}
963 		status.mft_attr_mapped = 1;
964 		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
965 				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
966 		if (unlikely(err)) {
967 			if (err == -ENOENT)
968 				err = -EIO;
969 			break;
970 		}
971 		m = ctx->mrec;
972 		a = ctx->attr;
973 		/*
974 		 * Find the runlist element with which the attribute extent
975 		 * starts.  Note, we cannot use the _attr_ version because we
976 		 * have mapped the mft record.  That is ok because we know the
977 		 * runlist fragment must be mapped already to have ever gotten
978 		 * here, so we can just use the _rl_ version.
979 		 */
980 		vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
981 		rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
982 		BUG_ON(!rl2);
983 		BUG_ON(!rl2->length);
984 		BUG_ON(rl2->lcn < LCN_HOLE);
985 		highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
986 		/*
987 		 * If @highest_vcn is zero, calculate the real highest_vcn
988 		 * (which can really be zero).
989 		 */
990 		if (!highest_vcn)
991 			highest_vcn = (sle64_to_cpu(
992 					a->data.non_resident.allocated_size) >>
993 					vol->cluster_size_bits) - 1;
994 		/*
995 		 * Determine the size of the mapping pairs array for the new
996 		 * extent, i.e. the old extent with the hole filled.
997 		 */
998 		mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
999 				highest_vcn);
1000 		if (unlikely(mp_size <= 0)) {
1001 			if (!(err = mp_size))
1002 				err = -EIO;
1003 			ntfs_debug("Failed to get size for mapping pairs "
1004 					"array, error code %i.", err);
1005 			break;
1006 		}
1007 		/*
1008 		 * Resize the attribute record to fit the new mapping pairs
1009 		 * array.
1010 		 */
1011 		attr_rec_len = le32_to_cpu(a->length);
1012 		err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
1013 				a->data.non_resident.mapping_pairs_offset));
1014 		if (unlikely(err)) {
1015 			BUG_ON(err != -ENOSPC);
1016 			// TODO: Deal with this by using the current attribute
1017 			// and fill it with as much of the mapping pairs
1018 			// array as possible.  Then loop over each attribute
1019 			// extent rewriting the mapping pairs arrays as we go
1020 			// along and if when we reach the end we have not
1021 			// enough space, try to resize the last attribute
1022 			// extent and if even that fails, add a new attribute
1023 			// extent.
1024 			// We could also try to resize at each step in the hope
1025 			// that we will not need to rewrite every single extent.
1026 			// Note, we may need to decompress some extents to fill
1027 			// the runlist as we are walking the extents...
1028 			ntfs_error(vol->sb, "Not enough space in the mft "
1029 					"record for the extended attribute "
1030 					"record.  This case is not "
1031 					"implemented yet.");
1032 			err = -EOPNOTSUPP;
1033 			break ;
1034 		}
1035 		status.mp_rebuilt = 1;
1036 		/*
1037 		 * Generate the mapping pairs array directly into the attribute
1038 		 * record.
1039 		 */
1040 		err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1041 				a->data.non_resident.mapping_pairs_offset),
1042 				mp_size, rl2, vcn, highest_vcn, NULL);
1043 		if (unlikely(err)) {
1044 			ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1045 					"attribute type 0x%x, because building "
1046 					"the mapping pairs failed with error "
1047 					"code %i.", vi->i_ino,
1048 					(unsigned)le32_to_cpu(ni->type), err);
1049 			err = -EIO;
1050 			break;
1051 		}
1052 		/* Update the highest_vcn but only if it was not set. */
1053 		if (unlikely(!a->data.non_resident.highest_vcn))
1054 			a->data.non_resident.highest_vcn =
1055 					cpu_to_sle64(highest_vcn);
1056 		/*
1057 		 * If the attribute is sparse/compressed, update the compressed
1058 		 * size in the ntfs_inode structure and the attribute record.
1059 		 */
1060 		if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1061 			/*
1062 			 * If we are not in the first attribute extent, switch
1063 			 * to it, but first ensure the changes will make it to
1064 			 * disk later.
1065 			 */
1066 			if (a->data.non_resident.lowest_vcn) {
1067 				flush_dcache_mft_record_page(ctx->ntfs_ino);
1068 				mark_mft_record_dirty(ctx->ntfs_ino);
1069 				ntfs_attr_reinit_search_ctx(ctx);
1070 				err = ntfs_attr_lookup(ni->type, ni->name,
1071 						ni->name_len, CASE_SENSITIVE,
1072 						0, NULL, 0, ctx);
1073 				if (unlikely(err)) {
1074 					status.attr_switched = 1;
1075 					break;
1076 				}
1077 				/* @m is not used any more so do not set it. */
1078 				a = ctx->attr;
1079 			}
1080 			write_lock_irqsave(&ni->size_lock, flags);
1081 			ni->itype.compressed.size += vol->cluster_size;
1082 			a->data.non_resident.compressed_size =
1083 					cpu_to_sle64(ni->itype.compressed.size);
1084 			write_unlock_irqrestore(&ni->size_lock, flags);
1085 		}
1086 		/* Ensure the changes make it to disk. */
1087 		flush_dcache_mft_record_page(ctx->ntfs_ino);
1088 		mark_mft_record_dirty(ctx->ntfs_ino);
1089 		ntfs_attr_put_search_ctx(ctx);
1090 		unmap_mft_record(base_ni);
1091 		/* Successfully filled the hole. */
1092 		status.runlist_merged = 0;
1093 		status.mft_attr_mapped = 0;
1094 		status.mp_rebuilt = 0;
1095 		/* Setup the map cache and use that to deal with the buffer. */
1096 		was_hole = TRUE;
1097 		vcn = bh_cpos;
1098 		vcn_len = 1;
1099 		lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1100 		cdelta = 0;
1101 		/*
1102 		 * If the number of remaining clusters in the @pages is smaller
1103 		 * or equal to the number of cached clusters, unlock the
1104 		 * runlist as the map cache will be used from now on.
1105 		 */
1106 		if (likely(vcn + vcn_len >= cend)) {
1107 			up_write(&ni->runlist.lock);
1108 			rl_write_locked = FALSE;
1109 			rl = NULL;
1110 		}
1111 		goto map_buffer_cached;
1112 	} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1113 	/* If there are no errors, do the next page. */
1114 	if (likely(!err && ++u < nr_pages))
1115 		goto do_next_page;
1116 	/* If there are no errors, release the runlist lock if we took it. */
1117 	if (likely(!err)) {
1118 		if (unlikely(rl_write_locked)) {
1119 			up_write(&ni->runlist.lock);
1120 			rl_write_locked = FALSE;
1121 		} else if (unlikely(rl))
1122 			up_read(&ni->runlist.lock);
1123 		rl = NULL;
1124 	}
1125 	/* If we issued read requests, let them complete. */
1126 	read_lock_irqsave(&ni->size_lock, flags);
1127 	initialized_size = ni->initialized_size;
1128 	read_unlock_irqrestore(&ni->size_lock, flags);
1129 	while (wait_bh > wait) {
1130 		bh = *--wait_bh;
1131 		wait_on_buffer(bh);
1132 		if (likely(buffer_uptodate(bh))) {
1133 			page = bh->b_page;
1134 			bh_pos = ((s64)page->index << PAGE_CACHE_SHIFT) +
1135 					bh_offset(bh);
1136 			/*
1137 			 * If the buffer overflows the initialized size, need
1138 			 * to zero the overflowing region.
1139 			 */
1140 			if (unlikely(bh_pos + blocksize > initialized_size)) {
1141 				u8 *kaddr;
1142 				int ofs = 0;
1143 
1144 				if (likely(bh_pos < initialized_size))
1145 					ofs = initialized_size - bh_pos;
1146 				kaddr = kmap_atomic(page, KM_USER0);
1147 				memset(kaddr + bh_offset(bh) + ofs, 0,
1148 						blocksize - ofs);
1149 				kunmap_atomic(kaddr, KM_USER0);
1150 				flush_dcache_page(page);
1151 			}
1152 		} else /* if (unlikely(!buffer_uptodate(bh))) */
1153 			err = -EIO;
1154 	}
1155 	if (likely(!err)) {
1156 		/* Clear buffer_new on all buffers. */
1157 		u = 0;
1158 		do {
1159 			bh = head = page_buffers(pages[u]);
1160 			do {
1161 				if (buffer_new(bh))
1162 					clear_buffer_new(bh);
1163 			} while ((bh = bh->b_this_page) != head);
1164 		} while (++u < nr_pages);
1165 		ntfs_debug("Done.");
1166 		return err;
1167 	}
1168 	if (status.attr_switched) {
1169 		/* Get back to the attribute extent we modified. */
1170 		ntfs_attr_reinit_search_ctx(ctx);
1171 		if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1172 				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1173 			ntfs_error(vol->sb, "Failed to find required "
1174 					"attribute extent of attribute in "
1175 					"error code path.  Run chkdsk to "
1176 					"recover.");
1177 			write_lock_irqsave(&ni->size_lock, flags);
1178 			ni->itype.compressed.size += vol->cluster_size;
1179 			write_unlock_irqrestore(&ni->size_lock, flags);
1180 			flush_dcache_mft_record_page(ctx->ntfs_ino);
1181 			mark_mft_record_dirty(ctx->ntfs_ino);
1182 			/*
1183 			 * The only thing that is now wrong is the compressed
1184 			 * size of the base attribute extent which chkdsk
1185 			 * should be able to fix.
1186 			 */
1187 			NVolSetErrors(vol);
1188 		} else {
1189 			m = ctx->mrec;
1190 			a = ctx->attr;
1191 			status.attr_switched = 0;
1192 		}
1193 	}
1194 	/*
1195 	 * If the runlist has been modified, need to restore it by punching a
1196 	 * hole into it and we then need to deallocate the on-disk cluster as
1197 	 * well.  Note, we only modify the runlist if we are able to generate a
1198 	 * new mapping pairs array, i.e. only when the mapped attribute extent
1199 	 * is not switched.
1200 	 */
1201 	if (status.runlist_merged && !status.attr_switched) {
1202 		BUG_ON(!rl_write_locked);
1203 		/* Make the file cluster we allocated sparse in the runlist. */
1204 		if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1205 			ntfs_error(vol->sb, "Failed to punch hole into "
1206 					"attribute runlist in error code "
1207 					"path.  Run chkdsk to recover the "
1208 					"lost cluster.");
1209 			make_bad_inode(vi);
1210 			make_bad_inode(VFS_I(base_ni));
1211 			NVolSetErrors(vol);
1212 		} else /* if (success) */ {
1213 			status.runlist_merged = 0;
1214 			/*
1215 			 * Deallocate the on-disk cluster we allocated but only
1216 			 * if we succeeded in punching its vcn out of the
1217 			 * runlist.
1218 			 */
1219 			down_write(&vol->lcnbmp_lock);
1220 			if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1221 				ntfs_error(vol->sb, "Failed to release "
1222 						"allocated cluster in error "
1223 						"code path.  Run chkdsk to "
1224 						"recover the lost cluster.");
1225 				NVolSetErrors(vol);
1226 			}
1227 			up_write(&vol->lcnbmp_lock);
1228 		}
1229 	}
1230 	/*
1231 	 * Resize the attribute record to its old size and rebuild the mapping
1232 	 * pairs array.  Note, we only can do this if the runlist has been
1233 	 * restored to its old state which also implies that the mapped
1234 	 * attribute extent is not switched.
1235 	 */
1236 	if (status.mp_rebuilt && !status.runlist_merged) {
1237 		if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1238 			ntfs_error(vol->sb, "Failed to restore attribute "
1239 					"record in error code path.  Run "
1240 					"chkdsk to recover.");
1241 			make_bad_inode(vi);
1242 			make_bad_inode(VFS_I(base_ni));
1243 			NVolSetErrors(vol);
1244 		} else /* if (success) */ {
1245 			if (ntfs_mapping_pairs_build(vol, (u8*)a +
1246 					le16_to_cpu(a->data.non_resident.
1247 					mapping_pairs_offset), attr_rec_len -
1248 					le16_to_cpu(a->data.non_resident.
1249 					mapping_pairs_offset), ni->runlist.rl,
1250 					vcn, highest_vcn, NULL)) {
1251 				ntfs_error(vol->sb, "Failed to restore "
1252 						"mapping pairs array in error "
1253 						"code path.  Run chkdsk to "
1254 						"recover.");
1255 				make_bad_inode(vi);
1256 				make_bad_inode(VFS_I(base_ni));
1257 				NVolSetErrors(vol);
1258 			}
1259 			flush_dcache_mft_record_page(ctx->ntfs_ino);
1260 			mark_mft_record_dirty(ctx->ntfs_ino);
1261 		}
1262 	}
1263 	/* Release the mft record and the attribute. */
1264 	if (status.mft_attr_mapped) {
1265 		ntfs_attr_put_search_ctx(ctx);
1266 		unmap_mft_record(base_ni);
1267 	}
1268 	/* Release the runlist lock. */
1269 	if (rl_write_locked)
1270 		up_write(&ni->runlist.lock);
1271 	else if (rl)
1272 		up_read(&ni->runlist.lock);
1273 	/*
1274 	 * Zero out any newly allocated blocks to avoid exposing stale data.
1275 	 * If BH_New is set, we know that the block was newly allocated above
1276 	 * and that it has not been fully zeroed and marked dirty yet.
1277 	 */
1278 	nr_pages = u;
1279 	u = 0;
1280 	end = bh_cpos << vol->cluster_size_bits;
1281 	do {
1282 		page = pages[u];
1283 		bh = head = page_buffers(page);
1284 		do {
1285 			if (u == nr_pages &&
1286 					((s64)page->index << PAGE_CACHE_SHIFT) +
1287 					bh_offset(bh) >= end)
1288 				break;
1289 			if (!buffer_new(bh))
1290 				continue;
1291 			clear_buffer_new(bh);
1292 			if (!buffer_uptodate(bh)) {
1293 				if (PageUptodate(page))
1294 					set_buffer_uptodate(bh);
1295 				else {
1296 					u8 *kaddr = kmap_atomic(page, KM_USER0);
1297 					memset(kaddr + bh_offset(bh), 0,
1298 							blocksize);
1299 					kunmap_atomic(kaddr, KM_USER0);
1300 					flush_dcache_page(page);
1301 					set_buffer_uptodate(bh);
1302 				}
1303 			}
1304 			mark_buffer_dirty(bh);
1305 		} while ((bh = bh->b_this_page) != head);
1306 	} while (++u <= nr_pages);
1307 	ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1308 	return err;
1309 }
1310 
1311 /*
1312  * Copy as much as we can into the pages and return the number of bytes which
1313  * were sucessfully copied.  If a fault is encountered then clear the pages
1314  * out to (ofs + bytes) and return the number of bytes which were copied.
1315  */
1316 static inline size_t ntfs_copy_from_user(struct page **pages,
1317 		unsigned nr_pages, unsigned ofs, const char __user *buf,
1318 		size_t bytes)
1319 {
1320 	struct page **last_page = pages + nr_pages;
1321 	char *kaddr;
1322 	size_t total = 0;
1323 	unsigned len;
1324 	int left;
1325 
1326 	do {
1327 		len = PAGE_CACHE_SIZE - ofs;
1328 		if (len > bytes)
1329 			len = bytes;
1330 		kaddr = kmap_atomic(*pages, KM_USER0);
1331 		left = __copy_from_user_inatomic(kaddr + ofs, buf, len);
1332 		kunmap_atomic(kaddr, KM_USER0);
1333 		if (unlikely(left)) {
1334 			/* Do it the slow way. */
1335 			kaddr = kmap(*pages);
1336 			left = __copy_from_user(kaddr + ofs, buf, len);
1337 			kunmap(*pages);
1338 			if (unlikely(left))
1339 				goto err_out;
1340 		}
1341 		total += len;
1342 		bytes -= len;
1343 		if (!bytes)
1344 			break;
1345 		buf += len;
1346 		ofs = 0;
1347 	} while (++pages < last_page);
1348 out:
1349 	return total;
1350 err_out:
1351 	total += len - left;
1352 	/* Zero the rest of the target like __copy_from_user(). */
1353 	while (++pages < last_page) {
1354 		bytes -= len;
1355 		if (!bytes)
1356 			break;
1357 		len = PAGE_CACHE_SIZE;
1358 		if (len > bytes)
1359 			len = bytes;
1360 		kaddr = kmap_atomic(*pages, KM_USER0);
1361 		memset(kaddr, 0, len);
1362 		kunmap_atomic(kaddr, KM_USER0);
1363 	}
1364 	goto out;
1365 }
1366 
1367 static size_t __ntfs_copy_from_user_iovec(char *vaddr,
1368 		const struct iovec *iov, size_t iov_ofs, size_t bytes)
1369 {
1370 	size_t total = 0;
1371 
1372 	while (1) {
1373 		const char __user *buf = iov->iov_base + iov_ofs;
1374 		unsigned len;
1375 		size_t left;
1376 
1377 		len = iov->iov_len - iov_ofs;
1378 		if (len > bytes)
1379 			len = bytes;
1380 		left = __copy_from_user_inatomic(vaddr, buf, len);
1381 		total += len;
1382 		bytes -= len;
1383 		vaddr += len;
1384 		if (unlikely(left)) {
1385 			/*
1386 			 * Zero the rest of the target like __copy_from_user().
1387 			 */
1388 			memset(vaddr, 0, bytes);
1389 			total -= left;
1390 			break;
1391 		}
1392 		if (!bytes)
1393 			break;
1394 		iov++;
1395 		iov_ofs = 0;
1396 	}
1397 	return total;
1398 }
1399 
1400 static inline void ntfs_set_next_iovec(const struct iovec **iovp,
1401 		size_t *iov_ofsp, size_t bytes)
1402 {
1403 	const struct iovec *iov = *iovp;
1404 	size_t iov_ofs = *iov_ofsp;
1405 
1406 	while (bytes) {
1407 		unsigned len;
1408 
1409 		len = iov->iov_len - iov_ofs;
1410 		if (len > bytes)
1411 			len = bytes;
1412 		bytes -= len;
1413 		iov_ofs += len;
1414 		if (iov->iov_len == iov_ofs) {
1415 			iov++;
1416 			iov_ofs = 0;
1417 		}
1418 	}
1419 	*iovp = iov;
1420 	*iov_ofsp = iov_ofs;
1421 }
1422 
1423 /*
1424  * This has the same side-effects and return value as ntfs_copy_from_user().
1425  * The difference is that on a fault we need to memset the remainder of the
1426  * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
1427  * single-segment behaviour.
1428  *
1429  * We call the same helper (__ntfs_copy_from_user_iovec()) both when atomic and
1430  * when not atomic.  This is ok because __ntfs_copy_from_user_iovec() calls
1431  * __copy_from_user_inatomic() and it is ok to call this when non-atomic.  In
1432  * fact, the only difference between __copy_from_user_inatomic() and
1433  * __copy_from_user() is that the latter calls might_sleep().  And on many
1434  * architectures __copy_from_user_inatomic() is just defined to
1435  * __copy_from_user() so it makes no difference at all on those architectures.
1436  */
1437 static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
1438 		unsigned nr_pages, unsigned ofs, const struct iovec **iov,
1439 		size_t *iov_ofs, size_t bytes)
1440 {
1441 	struct page **last_page = pages + nr_pages;
1442 	char *kaddr;
1443 	size_t copied, len, total = 0;
1444 
1445 	do {
1446 		len = PAGE_CACHE_SIZE - ofs;
1447 		if (len > bytes)
1448 			len = bytes;
1449 		kaddr = kmap_atomic(*pages, KM_USER0);
1450 		copied = __ntfs_copy_from_user_iovec(kaddr + ofs,
1451 				*iov, *iov_ofs, len);
1452 		kunmap_atomic(kaddr, KM_USER0);
1453 		if (unlikely(copied != len)) {
1454 			/* Do it the slow way. */
1455 			kaddr = kmap(*pages);
1456 			copied = __ntfs_copy_from_user_iovec(kaddr + ofs,
1457 					*iov, *iov_ofs, len);
1458 			kunmap(*pages);
1459 			if (unlikely(copied != len))
1460 				goto err_out;
1461 		}
1462 		total += len;
1463 		bytes -= len;
1464 		if (!bytes)
1465 			break;
1466 		ntfs_set_next_iovec(iov, iov_ofs, len);
1467 		ofs = 0;
1468 	} while (++pages < last_page);
1469 out:
1470 	return total;
1471 err_out:
1472 	total += copied;
1473 	/* Zero the rest of the target like __copy_from_user(). */
1474 	while (++pages < last_page) {
1475 		bytes -= len;
1476 		if (!bytes)
1477 			break;
1478 		len = PAGE_CACHE_SIZE;
1479 		if (len > bytes)
1480 			len = bytes;
1481 		kaddr = kmap_atomic(*pages, KM_USER0);
1482 		memset(kaddr, 0, len);
1483 		kunmap_atomic(kaddr, KM_USER0);
1484 	}
1485 	goto out;
1486 }
1487 
1488 static inline void ntfs_flush_dcache_pages(struct page **pages,
1489 		unsigned nr_pages)
1490 {
1491 	BUG_ON(!nr_pages);
1492 	do {
1493 		/*
1494 		 * Warning: Do not do the decrement at the same time as the
1495 		 * call because flush_dcache_page() is a NULL macro on i386
1496 		 * and hence the decrement never happens.
1497 		 */
1498 		flush_dcache_page(pages[nr_pages]);
1499 	} while (--nr_pages > 0);
1500 }
1501 
1502 /**
1503  * ntfs_commit_pages_after_non_resident_write - commit the received data
1504  * @pages:	array of destination pages
1505  * @nr_pages:	number of pages in @pages
1506  * @pos:	byte position in file at which the write begins
1507  * @bytes:	number of bytes to be written
1508  *
1509  * See description of ntfs_commit_pages_after_write(), below.
1510  */
1511 static inline int ntfs_commit_pages_after_non_resident_write(
1512 		struct page **pages, const unsigned nr_pages,
1513 		s64 pos, size_t bytes)
1514 {
1515 	s64 end, initialized_size;
1516 	struct inode *vi;
1517 	ntfs_inode *ni, *base_ni;
1518 	struct buffer_head *bh, *head;
1519 	ntfs_attr_search_ctx *ctx;
1520 	MFT_RECORD *m;
1521 	ATTR_RECORD *a;
1522 	unsigned long flags;
1523 	unsigned blocksize, u;
1524 	int err;
1525 
1526 	vi = pages[0]->mapping->host;
1527 	ni = NTFS_I(vi);
1528 	blocksize = 1 << vi->i_blkbits;
1529 	end = pos + bytes;
1530 	u = 0;
1531 	do {
1532 		s64 bh_pos;
1533 		struct page *page;
1534 		BOOL partial;
1535 
1536 		page = pages[u];
1537 		bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
1538 		bh = head = page_buffers(page);
1539 		partial = FALSE;
1540 		do {
1541 			s64 bh_end;
1542 
1543 			bh_end = bh_pos + blocksize;
1544 			if (bh_end <= pos || bh_pos >= end) {
1545 				if (!buffer_uptodate(bh))
1546 					partial = TRUE;
1547 			} else {
1548 				set_buffer_uptodate(bh);
1549 				mark_buffer_dirty(bh);
1550 			}
1551 		} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1552 		/*
1553 		 * If all buffers are now uptodate but the page is not, set the
1554 		 * page uptodate.
1555 		 */
1556 		if (!partial && !PageUptodate(page))
1557 			SetPageUptodate(page);
1558 	} while (++u < nr_pages);
1559 	/*
1560 	 * Finally, if we do not need to update initialized_size or i_size we
1561 	 * are finished.
1562 	 */
1563 	read_lock_irqsave(&ni->size_lock, flags);
1564 	initialized_size = ni->initialized_size;
1565 	read_unlock_irqrestore(&ni->size_lock, flags);
1566 	if (end <= initialized_size) {
1567 		ntfs_debug("Done.");
1568 		return 0;
1569 	}
1570 	/*
1571 	 * Update initialized_size/i_size as appropriate, both in the inode and
1572 	 * the mft record.
1573 	 */
1574 	if (!NInoAttr(ni))
1575 		base_ni = ni;
1576 	else
1577 		base_ni = ni->ext.base_ntfs_ino;
1578 	/* Map, pin, and lock the mft record. */
1579 	m = map_mft_record(base_ni);
1580 	if (IS_ERR(m)) {
1581 		err = PTR_ERR(m);
1582 		m = NULL;
1583 		ctx = NULL;
1584 		goto err_out;
1585 	}
1586 	BUG_ON(!NInoNonResident(ni));
1587 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1588 	if (unlikely(!ctx)) {
1589 		err = -ENOMEM;
1590 		goto err_out;
1591 	}
1592 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1593 			CASE_SENSITIVE, 0, NULL, 0, ctx);
1594 	if (unlikely(err)) {
1595 		if (err == -ENOENT)
1596 			err = -EIO;
1597 		goto err_out;
1598 	}
1599 	a = ctx->attr;
1600 	BUG_ON(!a->non_resident);
1601 	write_lock_irqsave(&ni->size_lock, flags);
1602 	BUG_ON(end > ni->allocated_size);
1603 	ni->initialized_size = end;
1604 	a->data.non_resident.initialized_size = cpu_to_sle64(end);
1605 	if (end > i_size_read(vi)) {
1606 		i_size_write(vi, end);
1607 		a->data.non_resident.data_size =
1608 				a->data.non_resident.initialized_size;
1609 	}
1610 	write_unlock_irqrestore(&ni->size_lock, flags);
1611 	/* Mark the mft record dirty, so it gets written back. */
1612 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1613 	mark_mft_record_dirty(ctx->ntfs_ino);
1614 	ntfs_attr_put_search_ctx(ctx);
1615 	unmap_mft_record(base_ni);
1616 	ntfs_debug("Done.");
1617 	return 0;
1618 err_out:
1619 	if (ctx)
1620 		ntfs_attr_put_search_ctx(ctx);
1621 	if (m)
1622 		unmap_mft_record(base_ni);
1623 	ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1624 			"code %i).", err);
1625 	if (err != -ENOMEM) {
1626 		NVolSetErrors(ni->vol);
1627 		make_bad_inode(VFS_I(base_ni));
1628 		make_bad_inode(vi);
1629 	}
1630 	return err;
1631 }
1632 
1633 /**
1634  * ntfs_commit_pages_after_write - commit the received data
1635  * @pages:	array of destination pages
1636  * @nr_pages:	number of pages in @pages
1637  * @pos:	byte position in file at which the write begins
1638  * @bytes:	number of bytes to be written
1639  *
1640  * This is called from ntfs_file_buffered_write() with i_sem held on the inode
1641  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1642  * locked but not kmap()ped.  The source data has already been copied into the
1643  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1644  * the data was copied (for non-resident attributes only) and it returned
1645  * success.
1646  *
1647  * Need to set uptodate and mark dirty all buffers within the boundary of the
1648  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1649  *
1650  * Setting the buffers dirty ensures that they get written out later when
1651  * ntfs_writepage() is invoked by the VM.
1652  *
1653  * Finally, we need to update i_size and initialized_size as appropriate both
1654  * in the inode and the mft record.
1655  *
1656  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1657  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1658  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1659  * that case, it also marks the inode dirty.
1660  *
1661  * If things have gone as outlined in
1662  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1663  * content modifications here for non-resident attributes.  For resident
1664  * attributes we need to do the uptodate bringing here which we combine with
1665  * the copying into the mft record which means we save one atomic kmap.
1666  *
1667  * Return 0 on success or -errno on error.
1668  */
1669 static int ntfs_commit_pages_after_write(struct page **pages,
1670 		const unsigned nr_pages, s64 pos, size_t bytes)
1671 {
1672 	s64 end, initialized_size;
1673 	loff_t i_size;
1674 	struct inode *vi;
1675 	ntfs_inode *ni, *base_ni;
1676 	struct page *page;
1677 	ntfs_attr_search_ctx *ctx;
1678 	MFT_RECORD *m;
1679 	ATTR_RECORD *a;
1680 	char *kattr, *kaddr;
1681 	unsigned long flags;
1682 	u32 attr_len;
1683 	int err;
1684 
1685 	BUG_ON(!nr_pages);
1686 	BUG_ON(!pages);
1687 	page = pages[0];
1688 	BUG_ON(!page);
1689 	vi = page->mapping->host;
1690 	ni = NTFS_I(vi);
1691 	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1692 			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1693 			vi->i_ino, ni->type, page->index, nr_pages,
1694 			(long long)pos, bytes);
1695 	if (NInoNonResident(ni))
1696 		return ntfs_commit_pages_after_non_resident_write(pages,
1697 				nr_pages, pos, bytes);
1698 	BUG_ON(nr_pages > 1);
1699 	/*
1700 	 * Attribute is resident, implying it is not compressed, encrypted, or
1701 	 * sparse.
1702 	 */
1703 	if (!NInoAttr(ni))
1704 		base_ni = ni;
1705 	else
1706 		base_ni = ni->ext.base_ntfs_ino;
1707 	BUG_ON(NInoNonResident(ni));
1708 	/* Map, pin, and lock the mft record. */
1709 	m = map_mft_record(base_ni);
1710 	if (IS_ERR(m)) {
1711 		err = PTR_ERR(m);
1712 		m = NULL;
1713 		ctx = NULL;
1714 		goto err_out;
1715 	}
1716 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1717 	if (unlikely(!ctx)) {
1718 		err = -ENOMEM;
1719 		goto err_out;
1720 	}
1721 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1722 			CASE_SENSITIVE, 0, NULL, 0, ctx);
1723 	if (unlikely(err)) {
1724 		if (err == -ENOENT)
1725 			err = -EIO;
1726 		goto err_out;
1727 	}
1728 	a = ctx->attr;
1729 	BUG_ON(a->non_resident);
1730 	/* The total length of the attribute value. */
1731 	attr_len = le32_to_cpu(a->data.resident.value_length);
1732 	i_size = i_size_read(vi);
1733 	BUG_ON(attr_len != i_size);
1734 	BUG_ON(pos > attr_len);
1735 	end = pos + bytes;
1736 	BUG_ON(end > le32_to_cpu(a->length) -
1737 			le16_to_cpu(a->data.resident.value_offset));
1738 	kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1739 	kaddr = kmap_atomic(page, KM_USER0);
1740 	/* Copy the received data from the page to the mft record. */
1741 	memcpy(kattr + pos, kaddr + pos, bytes);
1742 	/* Update the attribute length if necessary. */
1743 	if (end > attr_len) {
1744 		attr_len = end;
1745 		a->data.resident.value_length = cpu_to_le32(attr_len);
1746 	}
1747 	/*
1748 	 * If the page is not uptodate, bring the out of bounds area(s)
1749 	 * uptodate by copying data from the mft record to the page.
1750 	 */
1751 	if (!PageUptodate(page)) {
1752 		if (pos > 0)
1753 			memcpy(kaddr, kattr, pos);
1754 		if (end < attr_len)
1755 			memcpy(kaddr + end, kattr + end, attr_len - end);
1756 		/* Zero the region outside the end of the attribute value. */
1757 		memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1758 		flush_dcache_page(page);
1759 		SetPageUptodate(page);
1760 	}
1761 	kunmap_atomic(kaddr, KM_USER0);
1762 	/* Update initialized_size/i_size if necessary. */
1763 	read_lock_irqsave(&ni->size_lock, flags);
1764 	initialized_size = ni->initialized_size;
1765 	BUG_ON(end > ni->allocated_size);
1766 	read_unlock_irqrestore(&ni->size_lock, flags);
1767 	BUG_ON(initialized_size != i_size);
1768 	if (end > initialized_size) {
1769 		unsigned long flags;
1770 
1771 		write_lock_irqsave(&ni->size_lock, flags);
1772 		ni->initialized_size = end;
1773 		i_size_write(vi, end);
1774 		write_unlock_irqrestore(&ni->size_lock, flags);
1775 	}
1776 	/* Mark the mft record dirty, so it gets written back. */
1777 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1778 	mark_mft_record_dirty(ctx->ntfs_ino);
1779 	ntfs_attr_put_search_ctx(ctx);
1780 	unmap_mft_record(base_ni);
1781 	ntfs_debug("Done.");
1782 	return 0;
1783 err_out:
1784 	if (err == -ENOMEM) {
1785 		ntfs_warning(vi->i_sb, "Error allocating memory required to "
1786 				"commit the write.");
1787 		if (PageUptodate(page)) {
1788 			ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1789 					"dirty so the write will be retried "
1790 					"later on by the VM.");
1791 			/*
1792 			 * Put the page on mapping->dirty_pages, but leave its
1793 			 * buffers' dirty state as-is.
1794 			 */
1795 			__set_page_dirty_nobuffers(page);
1796 			err = 0;
1797 		} else
1798 			ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1799 					"data has been lost.");
1800 	} else {
1801 		ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1802 				"with error %i.", err);
1803 		NVolSetErrors(ni->vol);
1804 		make_bad_inode(VFS_I(base_ni));
1805 		make_bad_inode(vi);
1806 	}
1807 	if (ctx)
1808 		ntfs_attr_put_search_ctx(ctx);
1809 	if (m)
1810 		unmap_mft_record(base_ni);
1811 	return err;
1812 }
1813 
1814 /**
1815  * ntfs_file_buffered_write -
1816  *
1817  * Locking: The vfs is holding ->i_sem on the inode.
1818  */
1819 static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
1820 		const struct iovec *iov, unsigned long nr_segs,
1821 		loff_t pos, loff_t *ppos, size_t count)
1822 {
1823 	struct file *file = iocb->ki_filp;
1824 	struct address_space *mapping = file->f_mapping;
1825 	struct inode *vi = mapping->host;
1826 	ntfs_inode *ni = NTFS_I(vi);
1827 	ntfs_volume *vol = ni->vol;
1828 	struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1829 	struct page *cached_page = NULL;
1830 	char __user *buf = NULL;
1831 	s64 end, ll;
1832 	VCN last_vcn;
1833 	LCN lcn;
1834 	unsigned long flags;
1835 	size_t bytes, iov_ofs = 0;	/* Offset in the current iovec. */
1836 	ssize_t status, written;
1837 	unsigned nr_pages;
1838 	int err;
1839 	struct pagevec lru_pvec;
1840 
1841 	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
1842 			"pos 0x%llx, count 0x%lx.",
1843 			vi->i_ino, (unsigned)le32_to_cpu(ni->type),
1844 			(unsigned long long)pos, (unsigned long)count);
1845 	if (unlikely(!count))
1846 		return 0;
1847 	BUG_ON(NInoMstProtected(ni));
1848 	/*
1849 	 * If the attribute is not an index root and it is encrypted or
1850 	 * compressed, we cannot write to it yet.  Note we need to check for
1851 	 * AT_INDEX_ALLOCATION since this is the type of both directory and
1852 	 * index inodes.
1853 	 */
1854 	if (ni->type != AT_INDEX_ALLOCATION) {
1855 		/* If file is encrypted, deny access, just like NT4. */
1856 		if (NInoEncrypted(ni)) {
1857 			/*
1858 			 * Reminder for later: Encrypted files are _always_
1859 			 * non-resident so that the content can always be
1860 			 * encrypted.
1861 			 */
1862 			ntfs_debug("Denying write access to encrypted file.");
1863 			return -EACCES;
1864 		}
1865 		if (NInoCompressed(ni)) {
1866 			/* Only unnamed $DATA attribute can be compressed. */
1867 			BUG_ON(ni->type != AT_DATA);
1868 			BUG_ON(ni->name_len);
1869 			/*
1870 			 * Reminder for later: If resident, the data is not
1871 			 * actually compressed.  Only on the switch to non-
1872 			 * resident does compression kick in.  This is in
1873 			 * contrast to encrypted files (see above).
1874 			 */
1875 			ntfs_error(vi->i_sb, "Writing to compressed files is "
1876 					"not implemented yet.  Sorry.");
1877 			return -EOPNOTSUPP;
1878 		}
1879 	}
1880 	/*
1881 	 * If a previous ntfs_truncate() failed, repeat it and abort if it
1882 	 * fails again.
1883 	 */
1884 	if (unlikely(NInoTruncateFailed(ni))) {
1885 		down_write(&vi->i_alloc_sem);
1886 		err = ntfs_truncate(vi);
1887 		up_write(&vi->i_alloc_sem);
1888 		if (err || NInoTruncateFailed(ni)) {
1889 			if (!err)
1890 				err = -EIO;
1891 			ntfs_error(vol->sb, "Cannot perform write to inode "
1892 					"0x%lx, attribute type 0x%x, because "
1893 					"ntfs_truncate() failed (error code "
1894 					"%i).", vi->i_ino,
1895 					(unsigned)le32_to_cpu(ni->type), err);
1896 			return err;
1897 		}
1898 	}
1899 	/* The first byte after the write. */
1900 	end = pos + count;
1901 	/*
1902 	 * If the write goes beyond the allocated size, extend the allocation
1903 	 * to cover the whole of the write, rounded up to the nearest cluster.
1904 	 */
1905 	read_lock_irqsave(&ni->size_lock, flags);
1906 	ll = ni->allocated_size;
1907 	read_unlock_irqrestore(&ni->size_lock, flags);
1908 	if (end > ll) {
1909 		/* Extend the allocation without changing the data size. */
1910 		ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
1911 		if (likely(ll >= 0)) {
1912 			BUG_ON(pos >= ll);
1913 			/* If the extension was partial truncate the write. */
1914 			if (end > ll) {
1915 				ntfs_debug("Truncating write to inode 0x%lx, "
1916 						"attribute type 0x%x, because "
1917 						"the allocation was only "
1918 						"partially extended.",
1919 						vi->i_ino, (unsigned)
1920 						le32_to_cpu(ni->type));
1921 				end = ll;
1922 				count = ll - pos;
1923 			}
1924 		} else {
1925 			err = ll;
1926 			read_lock_irqsave(&ni->size_lock, flags);
1927 			ll = ni->allocated_size;
1928 			read_unlock_irqrestore(&ni->size_lock, flags);
1929 			/* Perform a partial write if possible or fail. */
1930 			if (pos < ll) {
1931 				ntfs_debug("Truncating write to inode 0x%lx, "
1932 						"attribute type 0x%x, because "
1933 						"extending the allocation "
1934 						"failed (error code %i).",
1935 						vi->i_ino, (unsigned)
1936 						le32_to_cpu(ni->type), err);
1937 				end = ll;
1938 				count = ll - pos;
1939 			} else {
1940 				ntfs_error(vol->sb, "Cannot perform write to "
1941 						"inode 0x%lx, attribute type "
1942 						"0x%x, because extending the "
1943 						"allocation failed (error "
1944 						"code %i).", vi->i_ino,
1945 						(unsigned)
1946 						le32_to_cpu(ni->type), err);
1947 				return err;
1948 			}
1949 		}
1950 	}
1951 	pagevec_init(&lru_pvec, 0);
1952 	written = 0;
1953 	/*
1954 	 * If the write starts beyond the initialized size, extend it up to the
1955 	 * beginning of the write and initialize all non-sparse space between
1956 	 * the old initialized size and the new one.  This automatically also
1957 	 * increments the vfs inode->i_size to keep it above or equal to the
1958 	 * initialized_size.
1959 	 */
1960 	read_lock_irqsave(&ni->size_lock, flags);
1961 	ll = ni->initialized_size;
1962 	read_unlock_irqrestore(&ni->size_lock, flags);
1963 	if (pos > ll) {
1964 		err = ntfs_attr_extend_initialized(ni, pos, &cached_page,
1965 				&lru_pvec);
1966 		if (err < 0) {
1967 			ntfs_error(vol->sb, "Cannot perform write to inode "
1968 					"0x%lx, attribute type 0x%x, because "
1969 					"extending the initialized size "
1970 					"failed (error code %i).", vi->i_ino,
1971 					(unsigned)le32_to_cpu(ni->type), err);
1972 			status = err;
1973 			goto err_out;
1974 		}
1975 	}
1976 	/*
1977 	 * Determine the number of pages per cluster for non-resident
1978 	 * attributes.
1979 	 */
1980 	nr_pages = 1;
1981 	if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
1982 		nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
1983 	/* Finally, perform the actual write. */
1984 	last_vcn = -1;
1985 	if (likely(nr_segs == 1))
1986 		buf = iov->iov_base;
1987 	do {
1988 		VCN vcn;
1989 		pgoff_t idx, start_idx;
1990 		unsigned ofs, do_pages, u;
1991 		size_t copied;
1992 
1993 		start_idx = idx = pos >> PAGE_CACHE_SHIFT;
1994 		ofs = pos & ~PAGE_CACHE_MASK;
1995 		bytes = PAGE_CACHE_SIZE - ofs;
1996 		do_pages = 1;
1997 		if (nr_pages > 1) {
1998 			vcn = pos >> vol->cluster_size_bits;
1999 			if (vcn != last_vcn) {
2000 				last_vcn = vcn;
2001 				/*
2002 				 * Get the lcn of the vcn the write is in.  If
2003 				 * it is a hole, need to lock down all pages in
2004 				 * the cluster.
2005 				 */
2006 				down_read(&ni->runlist.lock);
2007 				lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
2008 						vol->cluster_size_bits, FALSE);
2009 				up_read(&ni->runlist.lock);
2010 				if (unlikely(lcn < LCN_HOLE)) {
2011 					status = -EIO;
2012 					if (lcn == LCN_ENOMEM)
2013 						status = -ENOMEM;
2014 					else
2015 						ntfs_error(vol->sb, "Cannot "
2016 							"perform write to "
2017 							"inode 0x%lx, "
2018 							"attribute type 0x%x, "
2019 							"because the attribute "
2020 							"is corrupt.",
2021 							vi->i_ino, (unsigned)
2022 							le32_to_cpu(ni->type));
2023 					break;
2024 				}
2025 				if (lcn == LCN_HOLE) {
2026 					start_idx = (pos & ~(s64)
2027 							vol->cluster_size_mask)
2028 							>> PAGE_CACHE_SHIFT;
2029 					bytes = vol->cluster_size - (pos &
2030 							vol->cluster_size_mask);
2031 					do_pages = nr_pages;
2032 				}
2033 			}
2034 		}
2035 		if (bytes > count)
2036 			bytes = count;
2037 		/*
2038 		 * Bring in the user page(s) that we will copy from _first_.
2039 		 * Otherwise there is a nasty deadlock on copying from the same
2040 		 * page(s) as we are writing to, without it/them being marked
2041 		 * up-to-date.  Note, at present there is nothing to stop the
2042 		 * pages being swapped out between us bringing them into memory
2043 		 * and doing the actual copying.
2044 		 */
2045 		if (likely(nr_segs == 1))
2046 			ntfs_fault_in_pages_readable(buf, bytes);
2047 		else
2048 			ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
2049 		/* Get and lock @do_pages starting at index @start_idx. */
2050 		status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
2051 				pages, &cached_page, &lru_pvec);
2052 		if (unlikely(status))
2053 			break;
2054 		/*
2055 		 * For non-resident attributes, we need to fill any holes with
2056 		 * actual clusters and ensure all bufferes are mapped.  We also
2057 		 * need to bring uptodate any buffers that are only partially
2058 		 * being written to.
2059 		 */
2060 		if (NInoNonResident(ni)) {
2061 			status = ntfs_prepare_pages_for_non_resident_write(
2062 					pages, do_pages, pos, bytes);
2063 			if (unlikely(status)) {
2064 				loff_t i_size;
2065 
2066 				do {
2067 					unlock_page(pages[--do_pages]);
2068 					page_cache_release(pages[do_pages]);
2069 				} while (do_pages);
2070 				/*
2071 				 * The write preparation may have instantiated
2072 				 * allocated space outside i_size.  Trim this
2073 				 * off again.  We can ignore any errors in this
2074 				 * case as we will just be waisting a bit of
2075 				 * allocated space, which is not a disaster.
2076 				 */
2077 				i_size = i_size_read(vi);
2078 				if (pos + bytes > i_size)
2079 					vmtruncate(vi, i_size);
2080 				break;
2081 			}
2082 		}
2083 		u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
2084 		if (likely(nr_segs == 1)) {
2085 			copied = ntfs_copy_from_user(pages + u, do_pages - u,
2086 					ofs, buf, bytes);
2087 			buf += copied;
2088 		} else
2089 			copied = ntfs_copy_from_user_iovec(pages + u,
2090 					do_pages - u, ofs, &iov, &iov_ofs,
2091 					bytes);
2092 		ntfs_flush_dcache_pages(pages + u, do_pages - u);
2093 		status = ntfs_commit_pages_after_write(pages, do_pages, pos,
2094 				bytes);
2095 		if (likely(!status)) {
2096 			written += copied;
2097 			count -= copied;
2098 			pos += copied;
2099 			if (unlikely(copied != bytes))
2100 				status = -EFAULT;
2101 		}
2102 		do {
2103 			unlock_page(pages[--do_pages]);
2104 			mark_page_accessed(pages[do_pages]);
2105 			page_cache_release(pages[do_pages]);
2106 		} while (do_pages);
2107 		if (unlikely(status))
2108 			break;
2109 		balance_dirty_pages_ratelimited(mapping);
2110 		cond_resched();
2111 	} while (count);
2112 err_out:
2113 	*ppos = pos;
2114 	if (cached_page)
2115 		page_cache_release(cached_page);
2116 	/* For now, when the user asks for O_SYNC, we actually give O_DSYNC. */
2117 	if (likely(!status)) {
2118 		if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(vi))) {
2119 			if (!mapping->a_ops->writepage || !is_sync_kiocb(iocb))
2120 				status = generic_osync_inode(vi, mapping,
2121 						OSYNC_METADATA|OSYNC_DATA);
2122 		}
2123   	}
2124 	pagevec_lru_add(&lru_pvec);
2125 	ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
2126 			written ? "written" : "status", (unsigned long)written,
2127 			(long)status);
2128 	return written ? written : status;
2129 }
2130 
2131 /**
2132  * ntfs_file_aio_write_nolock -
2133  */
2134 static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
2135 		const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
2136 {
2137 	struct file *file = iocb->ki_filp;
2138 	struct address_space *mapping = file->f_mapping;
2139 	struct inode *inode = mapping->host;
2140 	loff_t pos;
2141 	unsigned long seg;
2142 	size_t count;		/* after file limit checks */
2143 	ssize_t written, err;
2144 
2145 	count = 0;
2146 	for (seg = 0; seg < nr_segs; seg++) {
2147 		const struct iovec *iv = &iov[seg];
2148 		/*
2149 		 * If any segment has a negative length, or the cumulative
2150 		 * length ever wraps negative then return -EINVAL.
2151 		 */
2152 		count += iv->iov_len;
2153 		if (unlikely((ssize_t)(count|iv->iov_len) < 0))
2154 			return -EINVAL;
2155 		if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2156 			continue;
2157 		if (!seg)
2158 			return -EFAULT;
2159 		nr_segs = seg;
2160 		count -= iv->iov_len;	/* This segment is no good */
2161 		break;
2162 	}
2163 	pos = *ppos;
2164 	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2165 	/* We can write back this queue in page reclaim. */
2166 	current->backing_dev_info = mapping->backing_dev_info;
2167 	written = 0;
2168 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2169 	if (err)
2170 		goto out;
2171 	if (!count)
2172 		goto out;
2173 	err = remove_suid(file->f_dentry);
2174 	if (err)
2175 		goto out;
2176 	inode_update_time(inode, 1);
2177 	written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
2178 			count);
2179 out:
2180 	current->backing_dev_info = NULL;
2181 	return written ? written : err;
2182 }
2183 
2184 /**
2185  * ntfs_file_aio_write -
2186  */
2187 static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const char __user *buf,
2188 		size_t count, loff_t pos)
2189 {
2190 	struct file *file = iocb->ki_filp;
2191 	struct address_space *mapping = file->f_mapping;
2192 	struct inode *inode = mapping->host;
2193 	ssize_t ret;
2194 	struct iovec local_iov = { .iov_base = (void __user *)buf,
2195 				   .iov_len = count };
2196 
2197 	BUG_ON(iocb->ki_pos != pos);
2198 
2199 	down(&inode->i_sem);
2200 	ret = ntfs_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
2201 	up(&inode->i_sem);
2202 	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2203 		int err = sync_page_range(inode, mapping, pos, ret);
2204 		if (err < 0)
2205 			ret = err;
2206 	}
2207 	return ret;
2208 }
2209 
2210 /**
2211  * ntfs_file_writev -
2212  *
2213  * Basically the same as generic_file_writev() except that it ends up calling
2214  * ntfs_file_aio_write_nolock() instead of __generic_file_aio_write_nolock().
2215  */
2216 static ssize_t ntfs_file_writev(struct file *file, const struct iovec *iov,
2217 		unsigned long nr_segs, loff_t *ppos)
2218 {
2219 	struct address_space *mapping = file->f_mapping;
2220 	struct inode *inode = mapping->host;
2221 	struct kiocb kiocb;
2222 	ssize_t ret;
2223 
2224 	down(&inode->i_sem);
2225 	init_sync_kiocb(&kiocb, file);
2226 	ret = ntfs_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2227 	if (ret == -EIOCBQUEUED)
2228 		ret = wait_on_sync_kiocb(&kiocb);
2229 	up(&inode->i_sem);
2230 	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2231 		int err = sync_page_range(inode, mapping, *ppos - ret, ret);
2232 		if (err < 0)
2233 			ret = err;
2234 	}
2235 	return ret;
2236 }
2237 
2238 /**
2239  * ntfs_file_write - simple wrapper for ntfs_file_writev()
2240  */
2241 static ssize_t ntfs_file_write(struct file *file, const char __user *buf,
2242 		size_t count, loff_t *ppos)
2243 {
2244 	struct iovec local_iov = { .iov_base = (void __user *)buf,
2245 				   .iov_len = count };
2246 
2247 	return ntfs_file_writev(file, &local_iov, 1, ppos);
2248 }
2249 
2250 /**
2251  * ntfs_file_fsync - sync a file to disk
2252  * @filp:	file to be synced
2253  * @dentry:	dentry describing the file to sync
2254  * @datasync:	if non-zero only flush user data and not metadata
2255  *
2256  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
2257  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
2258  *
2259  * If @datasync is false, write the mft record and all associated extent mft
2260  * records as well as the $DATA attribute and then sync the block device.
2261  *
2262  * If @datasync is true and the attribute is non-resident, we skip the writing
2263  * of the mft record and all associated extent mft records (this might still
2264  * happen due to the write_inode_now() call).
2265  *
2266  * Also, if @datasync is true, we do not wait on the inode to be written out
2267  * but we always wait on the page cache pages to be written out.
2268  *
2269  * Note: In the past @filp could be NULL so we ignore it as we don't need it
2270  * anyway.
2271  *
2272  * Locking: Caller must hold i_sem on the inode.
2273  *
2274  * TODO: We should probably also write all attribute/index inodes associated
2275  * with this inode but since we have no simple way of getting to them we ignore
2276  * this problem for now.
2277  */
2278 static int ntfs_file_fsync(struct file *filp, struct dentry *dentry,
2279 		int datasync)
2280 {
2281 	struct inode *vi = dentry->d_inode;
2282 	int err, ret = 0;
2283 
2284 	ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
2285 	BUG_ON(S_ISDIR(vi->i_mode));
2286 	if (!datasync || !NInoNonResident(NTFS_I(vi)))
2287 		ret = ntfs_write_inode(vi, 1);
2288 	write_inode_now(vi, !datasync);
2289 	/*
2290 	 * NOTE: If we were to use mapping->private_list (see ext2 and
2291 	 * fs/buffer.c) for dirty blocks then we could optimize the below to be
2292 	 * sync_mapping_buffers(vi->i_mapping).
2293 	 */
2294 	err = sync_blockdev(vi->i_sb->s_bdev);
2295 	if (unlikely(err && !ret))
2296 		ret = err;
2297 	if (likely(!ret))
2298 		ntfs_debug("Done.");
2299 	else
2300 		ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
2301 				"%u.", datasync ? "data" : "", vi->i_ino, -ret);
2302 	return ret;
2303 }
2304 
2305 #endif /* NTFS_RW */
2306 
2307 struct file_operations ntfs_file_ops = {
2308 	.llseek		= generic_file_llseek,	 /* Seek inside file. */
2309 	.read		= generic_file_read,	 /* Read from file. */
2310 	.aio_read	= generic_file_aio_read, /* Async read from file. */
2311 	.readv		= generic_file_readv,	 /* Read from file. */
2312 #ifdef NTFS_RW
2313 	.write		= ntfs_file_write,	 /* Write to file. */
2314 	.aio_write	= ntfs_file_aio_write,	 /* Async write to file. */
2315 	.writev		= ntfs_file_writev,	 /* Write to file. */
2316 	/*.release	= ,*/			 /* Last file is closed.  See
2317 						    fs/ext2/file.c::
2318 						    ext2_release_file() for
2319 						    how to use this to discard
2320 						    preallocated space for
2321 						    write opened files. */
2322 	.fsync		= ntfs_file_fsync,	 /* Sync a file to disk. */
2323 	/*.aio_fsync	= ,*/			 /* Sync all outstanding async
2324 						    i/o operations on a
2325 						    kiocb. */
2326 #endif /* NTFS_RW */
2327 	/*.ioctl	= ,*/			 /* Perform function on the
2328 						    mounted filesystem. */
2329 	.mmap		= generic_file_mmap,	 /* Mmap file. */
2330 	.open		= ntfs_file_open,	 /* Open file. */
2331 	.sendfile	= generic_file_sendfile, /* Zero-copy data send with
2332 						    the data source being on
2333 						    the ntfs partition.  We do
2334 						    not need to care about the
2335 						    data destination. */
2336 	/*.sendpage	= ,*/			 /* Zero-copy data send with
2337 						    the data destination being
2338 						    on the ntfs partition.  We
2339 						    do not need to care about
2340 						    the data source. */
2341 };
2342 
2343 struct inode_operations ntfs_file_inode_ops = {
2344 #ifdef NTFS_RW
2345 	.truncate	= ntfs_truncate_vfs,
2346 	.setattr	= ntfs_setattr,
2347 #endif /* NTFS_RW */
2348 };
2349 
2350 struct file_operations ntfs_empty_file_ops = {};
2351 
2352 struct inode_operations ntfs_empty_inode_ops = {};
2353