1 /*
2  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
3  *
4  * Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
5  *
6  * This program/include file is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License as published
8  * by the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program/include file is distributed in the hope that it will be
12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program (in the main directory of the Linux-NTFS
18  * distribution in the file COPYING); if not, write to the Free Software
19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21 
22 #include <linux/backing-dev.h>
23 #include <linux/buffer_head.h>
24 #include <linux/gfp.h>
25 #include <linux/pagemap.h>
26 #include <linux/pagevec.h>
27 #include <linux/sched/signal.h>
28 #include <linux/swap.h>
29 #include <linux/uio.h>
30 #include <linux/writeback.h>
31 
32 #include <asm/page.h>
33 #include <linux/uaccess.h>
34 
35 #include "attrib.h"
36 #include "bitmap.h"
37 #include "inode.h"
38 #include "debug.h"
39 #include "lcnalloc.h"
40 #include "malloc.h"
41 #include "mft.h"
42 #include "ntfs.h"
43 
44 /**
45  * ntfs_file_open - called when an inode is about to be opened
46  * @vi:		inode to be opened
47  * @filp:	file structure describing the inode
48  *
49  * Limit file size to the page cache limit on architectures where unsigned long
50  * is 32-bits. This is the most we can do for now without overflowing the page
51  * cache page index. Doing it this way means we don't run into problems because
52  * of existing too large files. It would be better to allow the user to read
53  * the beginning of the file but I doubt very much anyone is going to hit this
54  * check on a 32-bit architecture, so there is no point in adding the extra
55  * complexity required to support this.
56  *
57  * On 64-bit architectures, the check is hopefully optimized away by the
58  * compiler.
59  *
60  * After the check passes, just call generic_file_open() to do its work.
61  */
ntfs_file_open(struct inode * vi,struct file * filp)62 static int ntfs_file_open(struct inode *vi, struct file *filp)
63 {
64 	if (sizeof(unsigned long) < 8) {
65 		if (i_size_read(vi) > MAX_LFS_FILESIZE)
66 			return -EOVERFLOW;
67 	}
68 	return generic_file_open(vi, filp);
69 }
70 
71 #ifdef NTFS_RW
72 
73 /**
74  * ntfs_attr_extend_initialized - extend the initialized size of an attribute
75  * @ni:			ntfs inode of the attribute to extend
76  * @new_init_size:	requested new initialized size in bytes
77  *
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  * Return 0 on success and -errno on error.  In the case that an error is
101  * encountered it is possible that the initialized size will already have been
102  * incremented some way towards @new_init_size but it is guaranteed that if
103  * this is the case, the necessary zeroing will also have happened and that all
104  * metadata is self-consistent.
105  *
106  * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
107  *	    held by the caller.
108  */
ntfs_attr_extend_initialized(ntfs_inode * ni,const s64 new_init_size)109 static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size)
110 {
111 	s64 old_init_size;
112 	loff_t old_i_size;
113 	pgoff_t index, end_index;
114 	unsigned long flags;
115 	struct inode *vi = VFS_I(ni);
116 	ntfs_inode *base_ni;
117 	MFT_RECORD *m = NULL;
118 	ATTR_RECORD *a;
119 	ntfs_attr_search_ctx *ctx = NULL;
120 	struct address_space *mapping;
121 	struct page *page = NULL;
122 	u8 *kattr;
123 	int err;
124 	u32 attr_len;
125 
126 	read_lock_irqsave(&ni->size_lock, flags);
127 	old_init_size = ni->initialized_size;
128 	old_i_size = i_size_read(vi);
129 	BUG_ON(new_init_size > ni->allocated_size);
130 	read_unlock_irqrestore(&ni->size_lock, flags);
131 	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
132 			"old_initialized_size 0x%llx, "
133 			"new_initialized_size 0x%llx, i_size 0x%llx.",
134 			vi->i_ino, (unsigned)le32_to_cpu(ni->type),
135 			(unsigned long long)old_init_size,
136 			(unsigned long long)new_init_size, old_i_size);
137 	if (!NInoAttr(ni))
138 		base_ni = ni;
139 	else
140 		base_ni = ni->ext.base_ntfs_ino;
141 	/* Use goto to reduce indentation and we need the label below anyway. */
142 	if (NInoNonResident(ni))
143 		goto do_non_resident_extend;
144 	BUG_ON(old_init_size != old_i_size);
145 	m = map_mft_record(base_ni);
146 	if (IS_ERR(m)) {
147 		err = PTR_ERR(m);
148 		m = NULL;
149 		goto err_out;
150 	}
151 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
152 	if (unlikely(!ctx)) {
153 		err = -ENOMEM;
154 		goto err_out;
155 	}
156 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
157 			CASE_SENSITIVE, 0, NULL, 0, ctx);
158 	if (unlikely(err)) {
159 		if (err == -ENOENT)
160 			err = -EIO;
161 		goto err_out;
162 	}
163 	m = ctx->mrec;
164 	a = ctx->attr;
165 	BUG_ON(a->non_resident);
166 	/* The total length of the attribute value. */
167 	attr_len = le32_to_cpu(a->data.resident.value_length);
168 	BUG_ON(old_i_size != (loff_t)attr_len);
169 	/*
170 	 * Do the zeroing in the mft record and update the attribute size in
171 	 * the mft record.
172 	 */
173 	kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
174 	memset(kattr + attr_len, 0, new_init_size - attr_len);
175 	a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
176 	/* Finally, update the sizes in the vfs and ntfs inodes. */
177 	write_lock_irqsave(&ni->size_lock, flags);
178 	i_size_write(vi, new_init_size);
179 	ni->initialized_size = new_init_size;
180 	write_unlock_irqrestore(&ni->size_lock, flags);
181 	goto done;
182 do_non_resident_extend:
183 	/*
184 	 * If the new initialized size @new_init_size exceeds the current file
185 	 * size (vfs inode->i_size), we need to extend the file size to the
186 	 * new initialized size.
187 	 */
188 	if (new_init_size > old_i_size) {
189 		m = map_mft_record(base_ni);
190 		if (IS_ERR(m)) {
191 			err = PTR_ERR(m);
192 			m = NULL;
193 			goto err_out;
194 		}
195 		ctx = ntfs_attr_get_search_ctx(base_ni, m);
196 		if (unlikely(!ctx)) {
197 			err = -ENOMEM;
198 			goto err_out;
199 		}
200 		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
201 				CASE_SENSITIVE, 0, NULL, 0, ctx);
202 		if (unlikely(err)) {
203 			if (err == -ENOENT)
204 				err = -EIO;
205 			goto err_out;
206 		}
207 		m = ctx->mrec;
208 		a = ctx->attr;
209 		BUG_ON(!a->non_resident);
210 		BUG_ON(old_i_size != (loff_t)
211 				sle64_to_cpu(a->data.non_resident.data_size));
212 		a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
213 		flush_dcache_mft_record_page(ctx->ntfs_ino);
214 		mark_mft_record_dirty(ctx->ntfs_ino);
215 		/* Update the file size in the vfs inode. */
216 		i_size_write(vi, new_init_size);
217 		ntfs_attr_put_search_ctx(ctx);
218 		ctx = NULL;
219 		unmap_mft_record(base_ni);
220 		m = NULL;
221 	}
222 	mapping = vi->i_mapping;
223 	index = old_init_size >> PAGE_SHIFT;
224 	end_index = (new_init_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
225 	do {
226 		/*
227 		 * Read the page.  If the page is not present, this will zero
228 		 * the uninitialized regions for us.
229 		 */
230 		page = read_mapping_page(mapping, index, NULL);
231 		if (IS_ERR(page)) {
232 			err = PTR_ERR(page);
233 			goto init_err_out;
234 		}
235 		if (unlikely(PageError(page))) {
236 			put_page(page);
237 			err = -EIO;
238 			goto init_err_out;
239 		}
240 		/*
241 		 * Update the initialized size in the ntfs inode.  This is
242 		 * enough to make ntfs_writepage() work.
243 		 */
244 		write_lock_irqsave(&ni->size_lock, flags);
245 		ni->initialized_size = (s64)(index + 1) << PAGE_SHIFT;
246 		if (ni->initialized_size > new_init_size)
247 			ni->initialized_size = new_init_size;
248 		write_unlock_irqrestore(&ni->size_lock, flags);
249 		/* Set the page dirty so it gets written out. */
250 		set_page_dirty(page);
251 		put_page(page);
252 		/*
253 		 * Play nice with the vm and the rest of the system.  This is
254 		 * very much needed as we can potentially be modifying the
255 		 * initialised size from a very small value to a really huge
256 		 * value, e.g.
257 		 *	f = open(somefile, O_TRUNC);
258 		 *	truncate(f, 10GiB);
259 		 *	seek(f, 10GiB);
260 		 *	write(f, 1);
261 		 * And this would mean we would be marking dirty hundreds of
262 		 * thousands of pages or as in the above example more than
263 		 * two and a half million pages!
264 		 *
265 		 * TODO: For sparse pages could optimize this workload by using
266 		 * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
267 		 * would be set in readpage for sparse pages and here we would
268 		 * not need to mark dirty any pages which have this bit set.
269 		 * The only caveat is that we have to clear the bit everywhere
270 		 * where we allocate any clusters that lie in the page or that
271 		 * contain the page.
272 		 *
273 		 * TODO: An even greater optimization would be for us to only
274 		 * call readpage() on pages which are not in sparse regions as
275 		 * determined from the runlist.  This would greatly reduce the
276 		 * number of pages we read and make dirty in the case of sparse
277 		 * files.
278 		 */
279 		balance_dirty_pages_ratelimited(mapping);
280 		cond_resched();
281 	} while (++index < end_index);
282 	read_lock_irqsave(&ni->size_lock, flags);
283 	BUG_ON(ni->initialized_size != new_init_size);
284 	read_unlock_irqrestore(&ni->size_lock, flags);
285 	/* Now bring in sync the initialized_size in the mft record. */
286 	m = map_mft_record(base_ni);
287 	if (IS_ERR(m)) {
288 		err = PTR_ERR(m);
289 		m = NULL;
290 		goto init_err_out;
291 	}
292 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
293 	if (unlikely(!ctx)) {
294 		err = -ENOMEM;
295 		goto init_err_out;
296 	}
297 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
298 			CASE_SENSITIVE, 0, NULL, 0, ctx);
299 	if (unlikely(err)) {
300 		if (err == -ENOENT)
301 			err = -EIO;
302 		goto init_err_out;
303 	}
304 	m = ctx->mrec;
305 	a = ctx->attr;
306 	BUG_ON(!a->non_resident);
307 	a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
308 done:
309 	flush_dcache_mft_record_page(ctx->ntfs_ino);
310 	mark_mft_record_dirty(ctx->ntfs_ino);
311 	if (ctx)
312 		ntfs_attr_put_search_ctx(ctx);
313 	if (m)
314 		unmap_mft_record(base_ni);
315 	ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
316 			(unsigned long long)new_init_size, i_size_read(vi));
317 	return 0;
318 init_err_out:
319 	write_lock_irqsave(&ni->size_lock, flags);
320 	ni->initialized_size = old_init_size;
321 	write_unlock_irqrestore(&ni->size_lock, flags);
322 err_out:
323 	if (ctx)
324 		ntfs_attr_put_search_ctx(ctx);
325 	if (m)
326 		unmap_mft_record(base_ni);
327 	ntfs_debug("Failed.  Returning error code %i.", err);
328 	return err;
329 }
330 
ntfs_prepare_file_for_write(struct kiocb * iocb,struct iov_iter * from)331 static ssize_t ntfs_prepare_file_for_write(struct kiocb *iocb,
332 		struct iov_iter *from)
333 {
334 	loff_t pos;
335 	s64 end, ll;
336 	ssize_t err;
337 	unsigned long flags;
338 	struct file *file = iocb->ki_filp;
339 	struct inode *vi = file_inode(file);
340 	ntfs_inode *base_ni, *ni = NTFS_I(vi);
341 	ntfs_volume *vol = ni->vol;
342 
343 	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
344 			"0x%llx, count 0x%zx.", vi->i_ino,
345 			(unsigned)le32_to_cpu(ni->type),
346 			(unsigned long long)iocb->ki_pos,
347 			iov_iter_count(from));
348 	err = generic_write_checks(iocb, from);
349 	if (unlikely(err <= 0))
350 		goto out;
351 	/*
352 	 * All checks have passed.  Before we start doing any writing we want
353 	 * to abort any totally illegal writes.
354 	 */
355 	BUG_ON(NInoMstProtected(ni));
356 	BUG_ON(ni->type != AT_DATA);
357 	/* If file is encrypted, deny access, just like NT4. */
358 	if (NInoEncrypted(ni)) {
359 		/* Only $DATA attributes can be encrypted. */
360 		/*
361 		 * Reminder for later: Encrypted files are _always_
362 		 * non-resident so that the content can always be encrypted.
363 		 */
364 		ntfs_debug("Denying write access to encrypted file.");
365 		err = -EACCES;
366 		goto out;
367 	}
368 	if (NInoCompressed(ni)) {
369 		/* Only unnamed $DATA attribute can be compressed. */
370 		BUG_ON(ni->name_len);
371 		/*
372 		 * Reminder for later: If resident, the data is not actually
373 		 * compressed.  Only on the switch to non-resident does
374 		 * compression kick in.  This is in contrast to encrypted files
375 		 * (see above).
376 		 */
377 		ntfs_error(vi->i_sb, "Writing to compressed files is not "
378 				"implemented yet.  Sorry.");
379 		err = -EOPNOTSUPP;
380 		goto out;
381 	}
382 	base_ni = ni;
383 	if (NInoAttr(ni))
384 		base_ni = ni->ext.base_ntfs_ino;
385 	err = file_remove_privs(file);
386 	if (unlikely(err))
387 		goto out;
388 	/*
389 	 * Our ->update_time method always succeeds thus file_update_time()
390 	 * cannot fail either so there is no need to check the return code.
391 	 */
392 	file_update_time(file);
393 	pos = iocb->ki_pos;
394 	/* The first byte after the last cluster being written to. */
395 	end = (pos + iov_iter_count(from) + vol->cluster_size_mask) &
396 			~(u64)vol->cluster_size_mask;
397 	/*
398 	 * If the write goes beyond the allocated size, extend the allocation
399 	 * to cover the whole of the write, rounded up to the nearest cluster.
400 	 */
401 	read_lock_irqsave(&ni->size_lock, flags);
402 	ll = ni->allocated_size;
403 	read_unlock_irqrestore(&ni->size_lock, flags);
404 	if (end > ll) {
405 		/*
406 		 * Extend the allocation without changing the data size.
407 		 *
408 		 * Note we ensure the allocation is big enough to at least
409 		 * write some data but we do not require the allocation to be
410 		 * complete, i.e. it may be partial.
411 		 */
412 		ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
413 		if (likely(ll >= 0)) {
414 			BUG_ON(pos >= ll);
415 			/* If the extension was partial truncate the write. */
416 			if (end > ll) {
417 				ntfs_debug("Truncating write to inode 0x%lx, "
418 						"attribute type 0x%x, because "
419 						"the allocation was only "
420 						"partially extended.",
421 						vi->i_ino, (unsigned)
422 						le32_to_cpu(ni->type));
423 				iov_iter_truncate(from, ll - pos);
424 			}
425 		} else {
426 			err = ll;
427 			read_lock_irqsave(&ni->size_lock, flags);
428 			ll = ni->allocated_size;
429 			read_unlock_irqrestore(&ni->size_lock, flags);
430 			/* Perform a partial write if possible or fail. */
431 			if (pos < ll) {
432 				ntfs_debug("Truncating write to inode 0x%lx "
433 						"attribute type 0x%x, because "
434 						"extending the allocation "
435 						"failed (error %d).",
436 						vi->i_ino, (unsigned)
437 						le32_to_cpu(ni->type),
438 						(int)-err);
439 				iov_iter_truncate(from, ll - pos);
440 			} else {
441 				if (err != -ENOSPC)
442 					ntfs_error(vi->i_sb, "Cannot perform "
443 							"write to inode "
444 							"0x%lx, attribute "
445 							"type 0x%x, because "
446 							"extending the "
447 							"allocation failed "
448 							"(error %ld).",
449 							vi->i_ino, (unsigned)
450 							le32_to_cpu(ni->type),
451 							(long)-err);
452 				else
453 					ntfs_debug("Cannot perform write to "
454 							"inode 0x%lx, "
455 							"attribute type 0x%x, "
456 							"because there is not "
457 							"space left.",
458 							vi->i_ino, (unsigned)
459 							le32_to_cpu(ni->type));
460 				goto out;
461 			}
462 		}
463 	}
464 	/*
465 	 * If the write starts beyond the initialized size, extend it up to the
466 	 * beginning of the write and initialize all non-sparse space between
467 	 * the old initialized size and the new one.  This automatically also
468 	 * increments the vfs inode->i_size to keep it above or equal to the
469 	 * initialized_size.
470 	 */
471 	read_lock_irqsave(&ni->size_lock, flags);
472 	ll = ni->initialized_size;
473 	read_unlock_irqrestore(&ni->size_lock, flags);
474 	if (pos > ll) {
475 		/*
476 		 * Wait for ongoing direct i/o to complete before proceeding.
477 		 * New direct i/o cannot start as we hold i_mutex.
478 		 */
479 		inode_dio_wait(vi);
480 		err = ntfs_attr_extend_initialized(ni, pos);
481 		if (unlikely(err < 0))
482 			ntfs_error(vi->i_sb, "Cannot perform write to inode "
483 					"0x%lx, attribute type 0x%x, because "
484 					"extending the initialized size "
485 					"failed (error %d).", vi->i_ino,
486 					(unsigned)le32_to_cpu(ni->type),
487 					(int)-err);
488 	}
489 out:
490 	return err;
491 }
492 
493 /**
494  * __ntfs_grab_cache_pages - obtain a number of locked pages
495  * @mapping:	address space mapping from which to obtain page cache pages
496  * @index:	starting index in @mapping at which to begin obtaining pages
497  * @nr_pages:	number of page cache pages to obtain
498  * @pages:	array of pages in which to return the obtained page cache pages
499  * @cached_page: allocated but as yet unused page
500  *
501  * Obtain @nr_pages locked page cache pages from the mapping @mapping and
502  * starting at index @index.
503  *
504  * If a page is newly created, add it to lru list
505  *
506  * Note, the page locks are obtained in ascending page index order.
507  */
__ntfs_grab_cache_pages(struct address_space * mapping,pgoff_t index,const unsigned nr_pages,struct page ** pages,struct page ** cached_page)508 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
509 		pgoff_t index, const unsigned nr_pages, struct page **pages,
510 		struct page **cached_page)
511 {
512 	int err, nr;
513 
514 	BUG_ON(!nr_pages);
515 	err = nr = 0;
516 	do {
517 		pages[nr] = find_get_page_flags(mapping, index, FGP_LOCK |
518 				FGP_ACCESSED);
519 		if (!pages[nr]) {
520 			if (!*cached_page) {
521 				*cached_page = page_cache_alloc(mapping);
522 				if (unlikely(!*cached_page)) {
523 					err = -ENOMEM;
524 					goto err_out;
525 				}
526 			}
527 			err = add_to_page_cache_lru(*cached_page, mapping,
528 				   index,
529 				   mapping_gfp_constraint(mapping, GFP_KERNEL));
530 			if (unlikely(err)) {
531 				if (err == -EEXIST)
532 					continue;
533 				goto err_out;
534 			}
535 			pages[nr] = *cached_page;
536 			*cached_page = NULL;
537 		}
538 		index++;
539 		nr++;
540 	} while (nr < nr_pages);
541 out:
542 	return err;
543 err_out:
544 	while (nr > 0) {
545 		unlock_page(pages[--nr]);
546 		put_page(pages[nr]);
547 	}
548 	goto out;
549 }
550 
ntfs_submit_bh_for_read(struct buffer_head * bh)551 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
552 {
553 	lock_buffer(bh);
554 	get_bh(bh);
555 	bh->b_end_io = end_buffer_read_sync;
556 	return submit_bh(REQ_OP_READ, 0, bh);
557 }
558 
559 /**
560  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
561  * @pages:	array of destination pages
562  * @nr_pages:	number of pages in @pages
563  * @pos:	byte position in file at which the write begins
564  * @bytes:	number of bytes to be written
565  *
566  * This is called for non-resident attributes from ntfs_file_buffered_write()
567  * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
568  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
569  * data has not yet been copied into the @pages.
570  *
571  * Need to fill any holes with actual clusters, allocate buffers if necessary,
572  * ensure all the buffers are mapped, and bring uptodate any buffers that are
573  * only partially being written to.
574  *
575  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
576  * greater than PAGE_SIZE, that all pages in @pages are entirely inside
577  * the same cluster and that they are the entirety of that cluster, and that
578  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
579  *
580  * i_size is not to be modified yet.
581  *
582  * Return 0 on success or -errno on error.
583  */
ntfs_prepare_pages_for_non_resident_write(struct page ** pages,unsigned nr_pages,s64 pos,size_t bytes)584 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
585 		unsigned nr_pages, s64 pos, size_t bytes)
586 {
587 	VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
588 	LCN lcn;
589 	s64 bh_pos, vcn_len, end, initialized_size;
590 	sector_t lcn_block;
591 	struct page *page;
592 	struct inode *vi;
593 	ntfs_inode *ni, *base_ni = NULL;
594 	ntfs_volume *vol;
595 	runlist_element *rl, *rl2;
596 	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
597 	ntfs_attr_search_ctx *ctx = NULL;
598 	MFT_RECORD *m = NULL;
599 	ATTR_RECORD *a = NULL;
600 	unsigned long flags;
601 	u32 attr_rec_len = 0;
602 	unsigned blocksize, u;
603 	int err, mp_size;
604 	bool rl_write_locked, was_hole, is_retry;
605 	unsigned char blocksize_bits;
606 	struct {
607 		u8 runlist_merged:1;
608 		u8 mft_attr_mapped:1;
609 		u8 mp_rebuilt:1;
610 		u8 attr_switched:1;
611 	} status = { 0, 0, 0, 0 };
612 
613 	BUG_ON(!nr_pages);
614 	BUG_ON(!pages);
615 	BUG_ON(!*pages);
616 	vi = pages[0]->mapping->host;
617 	ni = NTFS_I(vi);
618 	vol = ni->vol;
619 	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
620 			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
621 			vi->i_ino, ni->type, pages[0]->index, nr_pages,
622 			(long long)pos, bytes);
623 	blocksize = vol->sb->s_blocksize;
624 	blocksize_bits = vol->sb->s_blocksize_bits;
625 	u = 0;
626 	do {
627 		page = pages[u];
628 		BUG_ON(!page);
629 		/*
630 		 * create_empty_buffers() will create uptodate/dirty buffers if
631 		 * the page is uptodate/dirty.
632 		 */
633 		if (!page_has_buffers(page)) {
634 			create_empty_buffers(page, blocksize, 0);
635 			if (unlikely(!page_has_buffers(page)))
636 				return -ENOMEM;
637 		}
638 	} while (++u < nr_pages);
639 	rl_write_locked = false;
640 	rl = NULL;
641 	err = 0;
642 	vcn = lcn = -1;
643 	vcn_len = 0;
644 	lcn_block = -1;
645 	was_hole = false;
646 	cpos = pos >> vol->cluster_size_bits;
647 	end = pos + bytes;
648 	cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
649 	/*
650 	 * Loop over each page and for each page over each buffer.  Use goto to
651 	 * reduce indentation.
652 	 */
653 	u = 0;
654 do_next_page:
655 	page = pages[u];
656 	bh_pos = (s64)page->index << PAGE_SHIFT;
657 	bh = head = page_buffers(page);
658 	do {
659 		VCN cdelta;
660 		s64 bh_end;
661 		unsigned bh_cofs;
662 
663 		/* Clear buffer_new on all buffers to reinitialise state. */
664 		if (buffer_new(bh))
665 			clear_buffer_new(bh);
666 		bh_end = bh_pos + blocksize;
667 		bh_cpos = bh_pos >> vol->cluster_size_bits;
668 		bh_cofs = bh_pos & vol->cluster_size_mask;
669 		if (buffer_mapped(bh)) {
670 			/*
671 			 * The buffer is already mapped.  If it is uptodate,
672 			 * ignore it.
673 			 */
674 			if (buffer_uptodate(bh))
675 				continue;
676 			/*
677 			 * The buffer is not uptodate.  If the page is uptodate
678 			 * set the buffer uptodate and otherwise ignore it.
679 			 */
680 			if (PageUptodate(page)) {
681 				set_buffer_uptodate(bh);
682 				continue;
683 			}
684 			/*
685 			 * Neither the page nor the buffer are uptodate.  If
686 			 * the buffer is only partially being written to, we
687 			 * need to read it in before the write, i.e. now.
688 			 */
689 			if ((bh_pos < pos && bh_end > pos) ||
690 					(bh_pos < end && bh_end > end)) {
691 				/*
692 				 * If the buffer is fully or partially within
693 				 * the initialized size, do an actual read.
694 				 * Otherwise, simply zero the buffer.
695 				 */
696 				read_lock_irqsave(&ni->size_lock, flags);
697 				initialized_size = ni->initialized_size;
698 				read_unlock_irqrestore(&ni->size_lock, flags);
699 				if (bh_pos < initialized_size) {
700 					ntfs_submit_bh_for_read(bh);
701 					*wait_bh++ = bh;
702 				} else {
703 					zero_user(page, bh_offset(bh),
704 							blocksize);
705 					set_buffer_uptodate(bh);
706 				}
707 			}
708 			continue;
709 		}
710 		/* Unmapped buffer.  Need to map it. */
711 		bh->b_bdev = vol->sb->s_bdev;
712 		/*
713 		 * If the current buffer is in the same clusters as the map
714 		 * cache, there is no need to check the runlist again.  The
715 		 * map cache is made up of @vcn, which is the first cached file
716 		 * cluster, @vcn_len which is the number of cached file
717 		 * clusters, @lcn is the device cluster corresponding to @vcn,
718 		 * and @lcn_block is the block number corresponding to @lcn.
719 		 */
720 		cdelta = bh_cpos - vcn;
721 		if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
722 map_buffer_cached:
723 			BUG_ON(lcn < 0);
724 			bh->b_blocknr = lcn_block +
725 					(cdelta << (vol->cluster_size_bits -
726 					blocksize_bits)) +
727 					(bh_cofs >> blocksize_bits);
728 			set_buffer_mapped(bh);
729 			/*
730 			 * If the page is uptodate so is the buffer.  If the
731 			 * buffer is fully outside the write, we ignore it if
732 			 * it was already allocated and we mark it dirty so it
733 			 * gets written out if we allocated it.  On the other
734 			 * hand, if we allocated the buffer but we are not
735 			 * marking it dirty we set buffer_new so we can do
736 			 * error recovery.
737 			 */
738 			if (PageUptodate(page)) {
739 				if (!buffer_uptodate(bh))
740 					set_buffer_uptodate(bh);
741 				if (unlikely(was_hole)) {
742 					/* We allocated the buffer. */
743 					clean_bdev_bh_alias(bh);
744 					if (bh_end <= pos || bh_pos >= end)
745 						mark_buffer_dirty(bh);
746 					else
747 						set_buffer_new(bh);
748 				}
749 				continue;
750 			}
751 			/* Page is _not_ uptodate. */
752 			if (likely(!was_hole)) {
753 				/*
754 				 * Buffer was already allocated.  If it is not
755 				 * uptodate and is only partially being written
756 				 * to, we need to read it in before the write,
757 				 * i.e. now.
758 				 */
759 				if (!buffer_uptodate(bh) && bh_pos < end &&
760 						bh_end > pos &&
761 						(bh_pos < pos ||
762 						bh_end > end)) {
763 					/*
764 					 * If the buffer is fully or partially
765 					 * within the initialized size, do an
766 					 * actual read.  Otherwise, simply zero
767 					 * the buffer.
768 					 */
769 					read_lock_irqsave(&ni->size_lock,
770 							flags);
771 					initialized_size = ni->initialized_size;
772 					read_unlock_irqrestore(&ni->size_lock,
773 							flags);
774 					if (bh_pos < initialized_size) {
775 						ntfs_submit_bh_for_read(bh);
776 						*wait_bh++ = bh;
777 					} else {
778 						zero_user(page, bh_offset(bh),
779 								blocksize);
780 						set_buffer_uptodate(bh);
781 					}
782 				}
783 				continue;
784 			}
785 			/* We allocated the buffer. */
786 			clean_bdev_bh_alias(bh);
787 			/*
788 			 * If the buffer is fully outside the write, zero it,
789 			 * set it uptodate, and mark it dirty so it gets
790 			 * written out.  If it is partially being written to,
791 			 * zero region surrounding the write but leave it to
792 			 * commit write to do anything else.  Finally, if the
793 			 * buffer is fully being overwritten, do nothing.
794 			 */
795 			if (bh_end <= pos || bh_pos >= end) {
796 				if (!buffer_uptodate(bh)) {
797 					zero_user(page, bh_offset(bh),
798 							blocksize);
799 					set_buffer_uptodate(bh);
800 				}
801 				mark_buffer_dirty(bh);
802 				continue;
803 			}
804 			set_buffer_new(bh);
805 			if (!buffer_uptodate(bh) &&
806 					(bh_pos < pos || bh_end > end)) {
807 				u8 *kaddr;
808 				unsigned pofs;
809 
810 				kaddr = kmap_atomic(page);
811 				if (bh_pos < pos) {
812 					pofs = bh_pos & ~PAGE_MASK;
813 					memset(kaddr + pofs, 0, pos - bh_pos);
814 				}
815 				if (bh_end > end) {
816 					pofs = end & ~PAGE_MASK;
817 					memset(kaddr + pofs, 0, bh_end - end);
818 				}
819 				kunmap_atomic(kaddr);
820 				flush_dcache_page(page);
821 			}
822 			continue;
823 		}
824 		/*
825 		 * Slow path: this is the first buffer in the cluster.  If it
826 		 * is outside allocated size and is not uptodate, zero it and
827 		 * set it uptodate.
828 		 */
829 		read_lock_irqsave(&ni->size_lock, flags);
830 		initialized_size = ni->allocated_size;
831 		read_unlock_irqrestore(&ni->size_lock, flags);
832 		if (bh_pos > initialized_size) {
833 			if (PageUptodate(page)) {
834 				if (!buffer_uptodate(bh))
835 					set_buffer_uptodate(bh);
836 			} else if (!buffer_uptodate(bh)) {
837 				zero_user(page, bh_offset(bh), blocksize);
838 				set_buffer_uptodate(bh);
839 			}
840 			continue;
841 		}
842 		is_retry = false;
843 		if (!rl) {
844 			down_read(&ni->runlist.lock);
845 retry_remap:
846 			rl = ni->runlist.rl;
847 		}
848 		if (likely(rl != NULL)) {
849 			/* Seek to element containing target cluster. */
850 			while (rl->length && rl[1].vcn <= bh_cpos)
851 				rl++;
852 			lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
853 			if (likely(lcn >= 0)) {
854 				/*
855 				 * Successful remap, setup the map cache and
856 				 * use that to deal with the buffer.
857 				 */
858 				was_hole = false;
859 				vcn = bh_cpos;
860 				vcn_len = rl[1].vcn - vcn;
861 				lcn_block = lcn << (vol->cluster_size_bits -
862 						blocksize_bits);
863 				cdelta = 0;
864 				/*
865 				 * If the number of remaining clusters touched
866 				 * by the write is smaller or equal to the
867 				 * number of cached clusters, unlock the
868 				 * runlist as the map cache will be used from
869 				 * now on.
870 				 */
871 				if (likely(vcn + vcn_len >= cend)) {
872 					if (rl_write_locked) {
873 						up_write(&ni->runlist.lock);
874 						rl_write_locked = false;
875 					} else
876 						up_read(&ni->runlist.lock);
877 					rl = NULL;
878 				}
879 				goto map_buffer_cached;
880 			}
881 		} else
882 			lcn = LCN_RL_NOT_MAPPED;
883 		/*
884 		 * If it is not a hole and not out of bounds, the runlist is
885 		 * probably unmapped so try to map it now.
886 		 */
887 		if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
888 			if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
889 				/* Attempt to map runlist. */
890 				if (!rl_write_locked) {
891 					/*
892 					 * We need the runlist locked for
893 					 * writing, so if it is locked for
894 					 * reading relock it now and retry in
895 					 * case it changed whilst we dropped
896 					 * the lock.
897 					 */
898 					up_read(&ni->runlist.lock);
899 					down_write(&ni->runlist.lock);
900 					rl_write_locked = true;
901 					goto retry_remap;
902 				}
903 				err = ntfs_map_runlist_nolock(ni, bh_cpos,
904 						NULL);
905 				if (likely(!err)) {
906 					is_retry = true;
907 					goto retry_remap;
908 				}
909 				/*
910 				 * If @vcn is out of bounds, pretend @lcn is
911 				 * LCN_ENOENT.  As long as the buffer is out
912 				 * of bounds this will work fine.
913 				 */
914 				if (err == -ENOENT) {
915 					lcn = LCN_ENOENT;
916 					err = 0;
917 					goto rl_not_mapped_enoent;
918 				}
919 			} else
920 				err = -EIO;
921 			/* Failed to map the buffer, even after retrying. */
922 			bh->b_blocknr = -1;
923 			ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
924 					"attribute type 0x%x, vcn 0x%llx, "
925 					"vcn offset 0x%x, because its "
926 					"location on disk could not be "
927 					"determined%s (error code %i).",
928 					ni->mft_no, ni->type,
929 					(unsigned long long)bh_cpos,
930 					(unsigned)bh_pos &
931 					vol->cluster_size_mask,
932 					is_retry ? " even after retrying" : "",
933 					err);
934 			break;
935 		}
936 rl_not_mapped_enoent:
937 		/*
938 		 * The buffer is in a hole or out of bounds.  We need to fill
939 		 * the hole, unless the buffer is in a cluster which is not
940 		 * touched by the write, in which case we just leave the buffer
941 		 * unmapped.  This can only happen when the cluster size is
942 		 * less than the page cache size.
943 		 */
944 		if (unlikely(vol->cluster_size < PAGE_SIZE)) {
945 			bh_cend = (bh_end + vol->cluster_size - 1) >>
946 					vol->cluster_size_bits;
947 			if ((bh_cend <= cpos || bh_cpos >= cend)) {
948 				bh->b_blocknr = -1;
949 				/*
950 				 * If the buffer is uptodate we skip it.  If it
951 				 * is not but the page is uptodate, we can set
952 				 * the buffer uptodate.  If the page is not
953 				 * uptodate, we can clear the buffer and set it
954 				 * uptodate.  Whether this is worthwhile is
955 				 * debatable and this could be removed.
956 				 */
957 				if (PageUptodate(page)) {
958 					if (!buffer_uptodate(bh))
959 						set_buffer_uptodate(bh);
960 				} else if (!buffer_uptodate(bh)) {
961 					zero_user(page, bh_offset(bh),
962 						blocksize);
963 					set_buffer_uptodate(bh);
964 				}
965 				continue;
966 			}
967 		}
968 		/*
969 		 * Out of bounds buffer is invalid if it was not really out of
970 		 * bounds.
971 		 */
972 		BUG_ON(lcn != LCN_HOLE);
973 		/*
974 		 * We need the runlist locked for writing, so if it is locked
975 		 * for reading relock it now and retry in case it changed
976 		 * whilst we dropped the lock.
977 		 */
978 		BUG_ON(!rl);
979 		if (!rl_write_locked) {
980 			up_read(&ni->runlist.lock);
981 			down_write(&ni->runlist.lock);
982 			rl_write_locked = true;
983 			goto retry_remap;
984 		}
985 		/* Find the previous last allocated cluster. */
986 		BUG_ON(rl->lcn != LCN_HOLE);
987 		lcn = -1;
988 		rl2 = rl;
989 		while (--rl2 >= ni->runlist.rl) {
990 			if (rl2->lcn >= 0) {
991 				lcn = rl2->lcn + rl2->length;
992 				break;
993 			}
994 		}
995 		rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
996 				false);
997 		if (IS_ERR(rl2)) {
998 			err = PTR_ERR(rl2);
999 			ntfs_debug("Failed to allocate cluster, error code %i.",
1000 					err);
1001 			break;
1002 		}
1003 		lcn = rl2->lcn;
1004 		rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
1005 		if (IS_ERR(rl)) {
1006 			err = PTR_ERR(rl);
1007 			if (err != -ENOMEM)
1008 				err = -EIO;
1009 			if (ntfs_cluster_free_from_rl(vol, rl2)) {
1010 				ntfs_error(vol->sb, "Failed to release "
1011 						"allocated cluster in error "
1012 						"code path.  Run chkdsk to "
1013 						"recover the lost cluster.");
1014 				NVolSetErrors(vol);
1015 			}
1016 			ntfs_free(rl2);
1017 			break;
1018 		}
1019 		ni->runlist.rl = rl;
1020 		status.runlist_merged = 1;
1021 		ntfs_debug("Allocated cluster, lcn 0x%llx.",
1022 				(unsigned long long)lcn);
1023 		/* Map and lock the mft record and get the attribute record. */
1024 		if (!NInoAttr(ni))
1025 			base_ni = ni;
1026 		else
1027 			base_ni = ni->ext.base_ntfs_ino;
1028 		m = map_mft_record(base_ni);
1029 		if (IS_ERR(m)) {
1030 			err = PTR_ERR(m);
1031 			break;
1032 		}
1033 		ctx = ntfs_attr_get_search_ctx(base_ni, m);
1034 		if (unlikely(!ctx)) {
1035 			err = -ENOMEM;
1036 			unmap_mft_record(base_ni);
1037 			break;
1038 		}
1039 		status.mft_attr_mapped = 1;
1040 		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1041 				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
1042 		if (unlikely(err)) {
1043 			if (err == -ENOENT)
1044 				err = -EIO;
1045 			break;
1046 		}
1047 		m = ctx->mrec;
1048 		a = ctx->attr;
1049 		/*
1050 		 * Find the runlist element with which the attribute extent
1051 		 * starts.  Note, we cannot use the _attr_ version because we
1052 		 * have mapped the mft record.  That is ok because we know the
1053 		 * runlist fragment must be mapped already to have ever gotten
1054 		 * here, so we can just use the _rl_ version.
1055 		 */
1056 		vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
1057 		rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
1058 		BUG_ON(!rl2);
1059 		BUG_ON(!rl2->length);
1060 		BUG_ON(rl2->lcn < LCN_HOLE);
1061 		highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
1062 		/*
1063 		 * If @highest_vcn is zero, calculate the real highest_vcn
1064 		 * (which can really be zero).
1065 		 */
1066 		if (!highest_vcn)
1067 			highest_vcn = (sle64_to_cpu(
1068 					a->data.non_resident.allocated_size) >>
1069 					vol->cluster_size_bits) - 1;
1070 		/*
1071 		 * Determine the size of the mapping pairs array for the new
1072 		 * extent, i.e. the old extent with the hole filled.
1073 		 */
1074 		mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
1075 				highest_vcn);
1076 		if (unlikely(mp_size <= 0)) {
1077 			if (!(err = mp_size))
1078 				err = -EIO;
1079 			ntfs_debug("Failed to get size for mapping pairs "
1080 					"array, error code %i.", err);
1081 			break;
1082 		}
1083 		/*
1084 		 * Resize the attribute record to fit the new mapping pairs
1085 		 * array.
1086 		 */
1087 		attr_rec_len = le32_to_cpu(a->length);
1088 		err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
1089 				a->data.non_resident.mapping_pairs_offset));
1090 		if (unlikely(err)) {
1091 			BUG_ON(err != -ENOSPC);
1092 			// TODO: Deal with this by using the current attribute
1093 			// and fill it with as much of the mapping pairs
1094 			// array as possible.  Then loop over each attribute
1095 			// extent rewriting the mapping pairs arrays as we go
1096 			// along and if when we reach the end we have not
1097 			// enough space, try to resize the last attribute
1098 			// extent and if even that fails, add a new attribute
1099 			// extent.
1100 			// We could also try to resize at each step in the hope
1101 			// that we will not need to rewrite every single extent.
1102 			// Note, we may need to decompress some extents to fill
1103 			// the runlist as we are walking the extents...
1104 			ntfs_error(vol->sb, "Not enough space in the mft "
1105 					"record for the extended attribute "
1106 					"record.  This case is not "
1107 					"implemented yet.");
1108 			err = -EOPNOTSUPP;
1109 			break ;
1110 		}
1111 		status.mp_rebuilt = 1;
1112 		/*
1113 		 * Generate the mapping pairs array directly into the attribute
1114 		 * record.
1115 		 */
1116 		err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1117 				a->data.non_resident.mapping_pairs_offset),
1118 				mp_size, rl2, vcn, highest_vcn, NULL);
1119 		if (unlikely(err)) {
1120 			ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1121 					"attribute type 0x%x, because building "
1122 					"the mapping pairs failed with error "
1123 					"code %i.", vi->i_ino,
1124 					(unsigned)le32_to_cpu(ni->type), err);
1125 			err = -EIO;
1126 			break;
1127 		}
1128 		/* Update the highest_vcn but only if it was not set. */
1129 		if (unlikely(!a->data.non_resident.highest_vcn))
1130 			a->data.non_resident.highest_vcn =
1131 					cpu_to_sle64(highest_vcn);
1132 		/*
1133 		 * If the attribute is sparse/compressed, update the compressed
1134 		 * size in the ntfs_inode structure and the attribute record.
1135 		 */
1136 		if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1137 			/*
1138 			 * If we are not in the first attribute extent, switch
1139 			 * to it, but first ensure the changes will make it to
1140 			 * disk later.
1141 			 */
1142 			if (a->data.non_resident.lowest_vcn) {
1143 				flush_dcache_mft_record_page(ctx->ntfs_ino);
1144 				mark_mft_record_dirty(ctx->ntfs_ino);
1145 				ntfs_attr_reinit_search_ctx(ctx);
1146 				err = ntfs_attr_lookup(ni->type, ni->name,
1147 						ni->name_len, CASE_SENSITIVE,
1148 						0, NULL, 0, ctx);
1149 				if (unlikely(err)) {
1150 					status.attr_switched = 1;
1151 					break;
1152 				}
1153 				/* @m is not used any more so do not set it. */
1154 				a = ctx->attr;
1155 			}
1156 			write_lock_irqsave(&ni->size_lock, flags);
1157 			ni->itype.compressed.size += vol->cluster_size;
1158 			a->data.non_resident.compressed_size =
1159 					cpu_to_sle64(ni->itype.compressed.size);
1160 			write_unlock_irqrestore(&ni->size_lock, flags);
1161 		}
1162 		/* Ensure the changes make it to disk. */
1163 		flush_dcache_mft_record_page(ctx->ntfs_ino);
1164 		mark_mft_record_dirty(ctx->ntfs_ino);
1165 		ntfs_attr_put_search_ctx(ctx);
1166 		unmap_mft_record(base_ni);
1167 		/* Successfully filled the hole. */
1168 		status.runlist_merged = 0;
1169 		status.mft_attr_mapped = 0;
1170 		status.mp_rebuilt = 0;
1171 		/* Setup the map cache and use that to deal with the buffer. */
1172 		was_hole = true;
1173 		vcn = bh_cpos;
1174 		vcn_len = 1;
1175 		lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1176 		cdelta = 0;
1177 		/*
1178 		 * If the number of remaining clusters in the @pages is smaller
1179 		 * or equal to the number of cached clusters, unlock the
1180 		 * runlist as the map cache will be used from now on.
1181 		 */
1182 		if (likely(vcn + vcn_len >= cend)) {
1183 			up_write(&ni->runlist.lock);
1184 			rl_write_locked = false;
1185 			rl = NULL;
1186 		}
1187 		goto map_buffer_cached;
1188 	} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1189 	/* If there are no errors, do the next page. */
1190 	if (likely(!err && ++u < nr_pages))
1191 		goto do_next_page;
1192 	/* If there are no errors, release the runlist lock if we took it. */
1193 	if (likely(!err)) {
1194 		if (unlikely(rl_write_locked)) {
1195 			up_write(&ni->runlist.lock);
1196 			rl_write_locked = false;
1197 		} else if (unlikely(rl))
1198 			up_read(&ni->runlist.lock);
1199 		rl = NULL;
1200 	}
1201 	/* If we issued read requests, let them complete. */
1202 	read_lock_irqsave(&ni->size_lock, flags);
1203 	initialized_size = ni->initialized_size;
1204 	read_unlock_irqrestore(&ni->size_lock, flags);
1205 	while (wait_bh > wait) {
1206 		bh = *--wait_bh;
1207 		wait_on_buffer(bh);
1208 		if (likely(buffer_uptodate(bh))) {
1209 			page = bh->b_page;
1210 			bh_pos = ((s64)page->index << PAGE_SHIFT) +
1211 					bh_offset(bh);
1212 			/*
1213 			 * If the buffer overflows the initialized size, need
1214 			 * to zero the overflowing region.
1215 			 */
1216 			if (unlikely(bh_pos + blocksize > initialized_size)) {
1217 				int ofs = 0;
1218 
1219 				if (likely(bh_pos < initialized_size))
1220 					ofs = initialized_size - bh_pos;
1221 				zero_user_segment(page, bh_offset(bh) + ofs,
1222 						blocksize);
1223 			}
1224 		} else /* if (unlikely(!buffer_uptodate(bh))) */
1225 			err = -EIO;
1226 	}
1227 	if (likely(!err)) {
1228 		/* Clear buffer_new on all buffers. */
1229 		u = 0;
1230 		do {
1231 			bh = head = page_buffers(pages[u]);
1232 			do {
1233 				if (buffer_new(bh))
1234 					clear_buffer_new(bh);
1235 			} while ((bh = bh->b_this_page) != head);
1236 		} while (++u < nr_pages);
1237 		ntfs_debug("Done.");
1238 		return err;
1239 	}
1240 	if (status.attr_switched) {
1241 		/* Get back to the attribute extent we modified. */
1242 		ntfs_attr_reinit_search_ctx(ctx);
1243 		if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1244 				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1245 			ntfs_error(vol->sb, "Failed to find required "
1246 					"attribute extent of attribute in "
1247 					"error code path.  Run chkdsk to "
1248 					"recover.");
1249 			write_lock_irqsave(&ni->size_lock, flags);
1250 			ni->itype.compressed.size += vol->cluster_size;
1251 			write_unlock_irqrestore(&ni->size_lock, flags);
1252 			flush_dcache_mft_record_page(ctx->ntfs_ino);
1253 			mark_mft_record_dirty(ctx->ntfs_ino);
1254 			/*
1255 			 * The only thing that is now wrong is the compressed
1256 			 * size of the base attribute extent which chkdsk
1257 			 * should be able to fix.
1258 			 */
1259 			NVolSetErrors(vol);
1260 		} else {
1261 			m = ctx->mrec;
1262 			a = ctx->attr;
1263 			status.attr_switched = 0;
1264 		}
1265 	}
1266 	/*
1267 	 * If the runlist has been modified, need to restore it by punching a
1268 	 * hole into it and we then need to deallocate the on-disk cluster as
1269 	 * well.  Note, we only modify the runlist if we are able to generate a
1270 	 * new mapping pairs array, i.e. only when the mapped attribute extent
1271 	 * is not switched.
1272 	 */
1273 	if (status.runlist_merged && !status.attr_switched) {
1274 		BUG_ON(!rl_write_locked);
1275 		/* Make the file cluster we allocated sparse in the runlist. */
1276 		if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1277 			ntfs_error(vol->sb, "Failed to punch hole into "
1278 					"attribute runlist in error code "
1279 					"path.  Run chkdsk to recover the "
1280 					"lost cluster.");
1281 			NVolSetErrors(vol);
1282 		} else /* if (success) */ {
1283 			status.runlist_merged = 0;
1284 			/*
1285 			 * Deallocate the on-disk cluster we allocated but only
1286 			 * if we succeeded in punching its vcn out of the
1287 			 * runlist.
1288 			 */
1289 			down_write(&vol->lcnbmp_lock);
1290 			if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1291 				ntfs_error(vol->sb, "Failed to release "
1292 						"allocated cluster in error "
1293 						"code path.  Run chkdsk to "
1294 						"recover the lost cluster.");
1295 				NVolSetErrors(vol);
1296 			}
1297 			up_write(&vol->lcnbmp_lock);
1298 		}
1299 	}
1300 	/*
1301 	 * Resize the attribute record to its old size and rebuild the mapping
1302 	 * pairs array.  Note, we only can do this if the runlist has been
1303 	 * restored to its old state which also implies that the mapped
1304 	 * attribute extent is not switched.
1305 	 */
1306 	if (status.mp_rebuilt && !status.runlist_merged) {
1307 		if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1308 			ntfs_error(vol->sb, "Failed to restore attribute "
1309 					"record in error code path.  Run "
1310 					"chkdsk to recover.");
1311 			NVolSetErrors(vol);
1312 		} else /* if (success) */ {
1313 			if (ntfs_mapping_pairs_build(vol, (u8*)a +
1314 					le16_to_cpu(a->data.non_resident.
1315 					mapping_pairs_offset), attr_rec_len -
1316 					le16_to_cpu(a->data.non_resident.
1317 					mapping_pairs_offset), ni->runlist.rl,
1318 					vcn, highest_vcn, NULL)) {
1319 				ntfs_error(vol->sb, "Failed to restore "
1320 						"mapping pairs array in error "
1321 						"code path.  Run chkdsk to "
1322 						"recover.");
1323 				NVolSetErrors(vol);
1324 			}
1325 			flush_dcache_mft_record_page(ctx->ntfs_ino);
1326 			mark_mft_record_dirty(ctx->ntfs_ino);
1327 		}
1328 	}
1329 	/* Release the mft record and the attribute. */
1330 	if (status.mft_attr_mapped) {
1331 		ntfs_attr_put_search_ctx(ctx);
1332 		unmap_mft_record(base_ni);
1333 	}
1334 	/* Release the runlist lock. */
1335 	if (rl_write_locked)
1336 		up_write(&ni->runlist.lock);
1337 	else if (rl)
1338 		up_read(&ni->runlist.lock);
1339 	/*
1340 	 * Zero out any newly allocated blocks to avoid exposing stale data.
1341 	 * If BH_New is set, we know that the block was newly allocated above
1342 	 * and that it has not been fully zeroed and marked dirty yet.
1343 	 */
1344 	nr_pages = u;
1345 	u = 0;
1346 	end = bh_cpos << vol->cluster_size_bits;
1347 	do {
1348 		page = pages[u];
1349 		bh = head = page_buffers(page);
1350 		do {
1351 			if (u == nr_pages &&
1352 					((s64)page->index << PAGE_SHIFT) +
1353 					bh_offset(bh) >= end)
1354 				break;
1355 			if (!buffer_new(bh))
1356 				continue;
1357 			clear_buffer_new(bh);
1358 			if (!buffer_uptodate(bh)) {
1359 				if (PageUptodate(page))
1360 					set_buffer_uptodate(bh);
1361 				else {
1362 					zero_user(page, bh_offset(bh),
1363 							blocksize);
1364 					set_buffer_uptodate(bh);
1365 				}
1366 			}
1367 			mark_buffer_dirty(bh);
1368 		} while ((bh = bh->b_this_page) != head);
1369 	} while (++u <= nr_pages);
1370 	ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1371 	return err;
1372 }
1373 
ntfs_flush_dcache_pages(struct page ** pages,unsigned nr_pages)1374 static inline void ntfs_flush_dcache_pages(struct page **pages,
1375 		unsigned nr_pages)
1376 {
1377 	BUG_ON(!nr_pages);
1378 	/*
1379 	 * Warning: Do not do the decrement at the same time as the call to
1380 	 * flush_dcache_page() because it is a NULL macro on i386 and hence the
1381 	 * decrement never happens so the loop never terminates.
1382 	 */
1383 	do {
1384 		--nr_pages;
1385 		flush_dcache_page(pages[nr_pages]);
1386 	} while (nr_pages > 0);
1387 }
1388 
1389 /**
1390  * ntfs_commit_pages_after_non_resident_write - commit the received data
1391  * @pages:	array of destination pages
1392  * @nr_pages:	number of pages in @pages
1393  * @pos:	byte position in file at which the write begins
1394  * @bytes:	number of bytes to be written
1395  *
1396  * See description of ntfs_commit_pages_after_write(), below.
1397  */
ntfs_commit_pages_after_non_resident_write(struct page ** pages,const unsigned nr_pages,s64 pos,size_t bytes)1398 static inline int ntfs_commit_pages_after_non_resident_write(
1399 		struct page **pages, const unsigned nr_pages,
1400 		s64 pos, size_t bytes)
1401 {
1402 	s64 end, initialized_size;
1403 	struct inode *vi;
1404 	ntfs_inode *ni, *base_ni;
1405 	struct buffer_head *bh, *head;
1406 	ntfs_attr_search_ctx *ctx;
1407 	MFT_RECORD *m;
1408 	ATTR_RECORD *a;
1409 	unsigned long flags;
1410 	unsigned blocksize, u;
1411 	int err;
1412 
1413 	vi = pages[0]->mapping->host;
1414 	ni = NTFS_I(vi);
1415 	blocksize = vi->i_sb->s_blocksize;
1416 	end = pos + bytes;
1417 	u = 0;
1418 	do {
1419 		s64 bh_pos;
1420 		struct page *page;
1421 		bool partial;
1422 
1423 		page = pages[u];
1424 		bh_pos = (s64)page->index << PAGE_SHIFT;
1425 		bh = head = page_buffers(page);
1426 		partial = false;
1427 		do {
1428 			s64 bh_end;
1429 
1430 			bh_end = bh_pos + blocksize;
1431 			if (bh_end <= pos || bh_pos >= end) {
1432 				if (!buffer_uptodate(bh))
1433 					partial = true;
1434 			} else {
1435 				set_buffer_uptodate(bh);
1436 				mark_buffer_dirty(bh);
1437 			}
1438 		} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1439 		/*
1440 		 * If all buffers are now uptodate but the page is not, set the
1441 		 * page uptodate.
1442 		 */
1443 		if (!partial && !PageUptodate(page))
1444 			SetPageUptodate(page);
1445 	} while (++u < nr_pages);
1446 	/*
1447 	 * Finally, if we do not need to update initialized_size or i_size we
1448 	 * are finished.
1449 	 */
1450 	read_lock_irqsave(&ni->size_lock, flags);
1451 	initialized_size = ni->initialized_size;
1452 	read_unlock_irqrestore(&ni->size_lock, flags);
1453 	if (end <= initialized_size) {
1454 		ntfs_debug("Done.");
1455 		return 0;
1456 	}
1457 	/*
1458 	 * Update initialized_size/i_size as appropriate, both in the inode and
1459 	 * the mft record.
1460 	 */
1461 	if (!NInoAttr(ni))
1462 		base_ni = ni;
1463 	else
1464 		base_ni = ni->ext.base_ntfs_ino;
1465 	/* Map, pin, and lock the mft record. */
1466 	m = map_mft_record(base_ni);
1467 	if (IS_ERR(m)) {
1468 		err = PTR_ERR(m);
1469 		m = NULL;
1470 		ctx = NULL;
1471 		goto err_out;
1472 	}
1473 	BUG_ON(!NInoNonResident(ni));
1474 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1475 	if (unlikely(!ctx)) {
1476 		err = -ENOMEM;
1477 		goto err_out;
1478 	}
1479 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1480 			CASE_SENSITIVE, 0, NULL, 0, ctx);
1481 	if (unlikely(err)) {
1482 		if (err == -ENOENT)
1483 			err = -EIO;
1484 		goto err_out;
1485 	}
1486 	a = ctx->attr;
1487 	BUG_ON(!a->non_resident);
1488 	write_lock_irqsave(&ni->size_lock, flags);
1489 	BUG_ON(end > ni->allocated_size);
1490 	ni->initialized_size = end;
1491 	a->data.non_resident.initialized_size = cpu_to_sle64(end);
1492 	if (end > i_size_read(vi)) {
1493 		i_size_write(vi, end);
1494 		a->data.non_resident.data_size =
1495 				a->data.non_resident.initialized_size;
1496 	}
1497 	write_unlock_irqrestore(&ni->size_lock, flags);
1498 	/* Mark the mft record dirty, so it gets written back. */
1499 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1500 	mark_mft_record_dirty(ctx->ntfs_ino);
1501 	ntfs_attr_put_search_ctx(ctx);
1502 	unmap_mft_record(base_ni);
1503 	ntfs_debug("Done.");
1504 	return 0;
1505 err_out:
1506 	if (ctx)
1507 		ntfs_attr_put_search_ctx(ctx);
1508 	if (m)
1509 		unmap_mft_record(base_ni);
1510 	ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1511 			"code %i).", err);
1512 	if (err != -ENOMEM)
1513 		NVolSetErrors(ni->vol);
1514 	return err;
1515 }
1516 
1517 /**
1518  * ntfs_commit_pages_after_write - commit the received data
1519  * @pages:	array of destination pages
1520  * @nr_pages:	number of pages in @pages
1521  * @pos:	byte position in file at which the write begins
1522  * @bytes:	number of bytes to be written
1523  *
1524  * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
1525  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1526  * locked but not kmap()ped.  The source data has already been copied into the
1527  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1528  * the data was copied (for non-resident attributes only) and it returned
1529  * success.
1530  *
1531  * Need to set uptodate and mark dirty all buffers within the boundary of the
1532  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1533  *
1534  * Setting the buffers dirty ensures that they get written out later when
1535  * ntfs_writepage() is invoked by the VM.
1536  *
1537  * Finally, we need to update i_size and initialized_size as appropriate both
1538  * in the inode and the mft record.
1539  *
1540  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1541  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1542  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1543  * that case, it also marks the inode dirty.
1544  *
1545  * If things have gone as outlined in
1546  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1547  * content modifications here for non-resident attributes.  For resident
1548  * attributes we need to do the uptodate bringing here which we combine with
1549  * the copying into the mft record which means we save one atomic kmap.
1550  *
1551  * Return 0 on success or -errno on error.
1552  */
ntfs_commit_pages_after_write(struct page ** pages,const unsigned nr_pages,s64 pos,size_t bytes)1553 static int ntfs_commit_pages_after_write(struct page **pages,
1554 		const unsigned nr_pages, s64 pos, size_t bytes)
1555 {
1556 	s64 end, initialized_size;
1557 	loff_t i_size;
1558 	struct inode *vi;
1559 	ntfs_inode *ni, *base_ni;
1560 	struct page *page;
1561 	ntfs_attr_search_ctx *ctx;
1562 	MFT_RECORD *m;
1563 	ATTR_RECORD *a;
1564 	char *kattr, *kaddr;
1565 	unsigned long flags;
1566 	u32 attr_len;
1567 	int err;
1568 
1569 	BUG_ON(!nr_pages);
1570 	BUG_ON(!pages);
1571 	page = pages[0];
1572 	BUG_ON(!page);
1573 	vi = page->mapping->host;
1574 	ni = NTFS_I(vi);
1575 	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1576 			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1577 			vi->i_ino, ni->type, page->index, nr_pages,
1578 			(long long)pos, bytes);
1579 	if (NInoNonResident(ni))
1580 		return ntfs_commit_pages_after_non_resident_write(pages,
1581 				nr_pages, pos, bytes);
1582 	BUG_ON(nr_pages > 1);
1583 	/*
1584 	 * Attribute is resident, implying it is not compressed, encrypted, or
1585 	 * sparse.
1586 	 */
1587 	if (!NInoAttr(ni))
1588 		base_ni = ni;
1589 	else
1590 		base_ni = ni->ext.base_ntfs_ino;
1591 	BUG_ON(NInoNonResident(ni));
1592 	/* Map, pin, and lock the mft record. */
1593 	m = map_mft_record(base_ni);
1594 	if (IS_ERR(m)) {
1595 		err = PTR_ERR(m);
1596 		m = NULL;
1597 		ctx = NULL;
1598 		goto err_out;
1599 	}
1600 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1601 	if (unlikely(!ctx)) {
1602 		err = -ENOMEM;
1603 		goto err_out;
1604 	}
1605 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1606 			CASE_SENSITIVE, 0, NULL, 0, ctx);
1607 	if (unlikely(err)) {
1608 		if (err == -ENOENT)
1609 			err = -EIO;
1610 		goto err_out;
1611 	}
1612 	a = ctx->attr;
1613 	BUG_ON(a->non_resident);
1614 	/* The total length of the attribute value. */
1615 	attr_len = le32_to_cpu(a->data.resident.value_length);
1616 	i_size = i_size_read(vi);
1617 	BUG_ON(attr_len != i_size);
1618 	BUG_ON(pos > attr_len);
1619 	end = pos + bytes;
1620 	BUG_ON(end > le32_to_cpu(a->length) -
1621 			le16_to_cpu(a->data.resident.value_offset));
1622 	kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1623 	kaddr = kmap_atomic(page);
1624 	/* Copy the received data from the page to the mft record. */
1625 	memcpy(kattr + pos, kaddr + pos, bytes);
1626 	/* Update the attribute length if necessary. */
1627 	if (end > attr_len) {
1628 		attr_len = end;
1629 		a->data.resident.value_length = cpu_to_le32(attr_len);
1630 	}
1631 	/*
1632 	 * If the page is not uptodate, bring the out of bounds area(s)
1633 	 * uptodate by copying data from the mft record to the page.
1634 	 */
1635 	if (!PageUptodate(page)) {
1636 		if (pos > 0)
1637 			memcpy(kaddr, kattr, pos);
1638 		if (end < attr_len)
1639 			memcpy(kaddr + end, kattr + end, attr_len - end);
1640 		/* Zero the region outside the end of the attribute value. */
1641 		memset(kaddr + attr_len, 0, PAGE_SIZE - attr_len);
1642 		flush_dcache_page(page);
1643 		SetPageUptodate(page);
1644 	}
1645 	kunmap_atomic(kaddr);
1646 	/* Update initialized_size/i_size if necessary. */
1647 	read_lock_irqsave(&ni->size_lock, flags);
1648 	initialized_size = ni->initialized_size;
1649 	BUG_ON(end > ni->allocated_size);
1650 	read_unlock_irqrestore(&ni->size_lock, flags);
1651 	BUG_ON(initialized_size != i_size);
1652 	if (end > initialized_size) {
1653 		write_lock_irqsave(&ni->size_lock, flags);
1654 		ni->initialized_size = end;
1655 		i_size_write(vi, end);
1656 		write_unlock_irqrestore(&ni->size_lock, flags);
1657 	}
1658 	/* Mark the mft record dirty, so it gets written back. */
1659 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1660 	mark_mft_record_dirty(ctx->ntfs_ino);
1661 	ntfs_attr_put_search_ctx(ctx);
1662 	unmap_mft_record(base_ni);
1663 	ntfs_debug("Done.");
1664 	return 0;
1665 err_out:
1666 	if (err == -ENOMEM) {
1667 		ntfs_warning(vi->i_sb, "Error allocating memory required to "
1668 				"commit the write.");
1669 		if (PageUptodate(page)) {
1670 			ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1671 					"dirty so the write will be retried "
1672 					"later on by the VM.");
1673 			/*
1674 			 * Put the page on mapping->dirty_pages, but leave its
1675 			 * buffers' dirty state as-is.
1676 			 */
1677 			__set_page_dirty_nobuffers(page);
1678 			err = 0;
1679 		} else
1680 			ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1681 					"data has been lost.");
1682 	} else {
1683 		ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1684 				"with error %i.", err);
1685 		NVolSetErrors(ni->vol);
1686 	}
1687 	if (ctx)
1688 		ntfs_attr_put_search_ctx(ctx);
1689 	if (m)
1690 		unmap_mft_record(base_ni);
1691 	return err;
1692 }
1693 
1694 /*
1695  * Copy as much as we can into the pages and return the number of bytes which
1696  * were successfully copied.  If a fault is encountered then clear the pages
1697  * out to (ofs + bytes) and return the number of bytes which were copied.
1698  */
ntfs_copy_from_user_iter(struct page ** pages,unsigned nr_pages,unsigned ofs,struct iov_iter * i,size_t bytes)1699 static size_t ntfs_copy_from_user_iter(struct page **pages, unsigned nr_pages,
1700 		unsigned ofs, struct iov_iter *i, size_t bytes)
1701 {
1702 	struct page **last_page = pages + nr_pages;
1703 	size_t total = 0;
1704 	struct iov_iter data = *i;
1705 	unsigned len, copied;
1706 
1707 	do {
1708 		len = PAGE_SIZE - ofs;
1709 		if (len > bytes)
1710 			len = bytes;
1711 		copied = iov_iter_copy_from_user_atomic(*pages, &data, ofs,
1712 				len);
1713 		total += copied;
1714 		bytes -= copied;
1715 		if (!bytes)
1716 			break;
1717 		iov_iter_advance(&data, copied);
1718 		if (copied < len)
1719 			goto err;
1720 		ofs = 0;
1721 	} while (++pages < last_page);
1722 out:
1723 	return total;
1724 err:
1725 	/* Zero the rest of the target like __copy_from_user(). */
1726 	len = PAGE_SIZE - copied;
1727 	do {
1728 		if (len > bytes)
1729 			len = bytes;
1730 		zero_user(*pages, copied, len);
1731 		bytes -= len;
1732 		copied = 0;
1733 		len = PAGE_SIZE;
1734 	} while (++pages < last_page);
1735 	goto out;
1736 }
1737 
1738 /**
1739  * ntfs_perform_write - perform buffered write to a file
1740  * @file:	file to write to
1741  * @i:		iov_iter with data to write
1742  * @pos:	byte offset in file at which to begin writing to
1743  */
ntfs_perform_write(struct file * file,struct iov_iter * i,loff_t pos)1744 static ssize_t ntfs_perform_write(struct file *file, struct iov_iter *i,
1745 		loff_t pos)
1746 {
1747 	struct address_space *mapping = file->f_mapping;
1748 	struct inode *vi = mapping->host;
1749 	ntfs_inode *ni = NTFS_I(vi);
1750 	ntfs_volume *vol = ni->vol;
1751 	struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1752 	struct page *cached_page = NULL;
1753 	VCN last_vcn;
1754 	LCN lcn;
1755 	size_t bytes;
1756 	ssize_t status, written = 0;
1757 	unsigned nr_pages;
1758 
1759 	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
1760 			"0x%llx, count 0x%lx.", vi->i_ino,
1761 			(unsigned)le32_to_cpu(ni->type),
1762 			(unsigned long long)pos,
1763 			(unsigned long)iov_iter_count(i));
1764 	/*
1765 	 * If a previous ntfs_truncate() failed, repeat it and abort if it
1766 	 * fails again.
1767 	 */
1768 	if (unlikely(NInoTruncateFailed(ni))) {
1769 		int err;
1770 
1771 		inode_dio_wait(vi);
1772 		err = ntfs_truncate(vi);
1773 		if (err || NInoTruncateFailed(ni)) {
1774 			if (!err)
1775 				err = -EIO;
1776 			ntfs_error(vol->sb, "Cannot perform write to inode "
1777 					"0x%lx, attribute type 0x%x, because "
1778 					"ntfs_truncate() failed (error code "
1779 					"%i).", vi->i_ino,
1780 					(unsigned)le32_to_cpu(ni->type), err);
1781 			return err;
1782 		}
1783 	}
1784 	/*
1785 	 * Determine the number of pages per cluster for non-resident
1786 	 * attributes.
1787 	 */
1788 	nr_pages = 1;
1789 	if (vol->cluster_size > PAGE_SIZE && NInoNonResident(ni))
1790 		nr_pages = vol->cluster_size >> PAGE_SHIFT;
1791 	last_vcn = -1;
1792 	do {
1793 		VCN vcn;
1794 		pgoff_t idx, start_idx;
1795 		unsigned ofs, do_pages, u;
1796 		size_t copied;
1797 
1798 		start_idx = idx = pos >> PAGE_SHIFT;
1799 		ofs = pos & ~PAGE_MASK;
1800 		bytes = PAGE_SIZE - ofs;
1801 		do_pages = 1;
1802 		if (nr_pages > 1) {
1803 			vcn = pos >> vol->cluster_size_bits;
1804 			if (vcn != last_vcn) {
1805 				last_vcn = vcn;
1806 				/*
1807 				 * Get the lcn of the vcn the write is in.  If
1808 				 * it is a hole, need to lock down all pages in
1809 				 * the cluster.
1810 				 */
1811 				down_read(&ni->runlist.lock);
1812 				lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
1813 						vol->cluster_size_bits, false);
1814 				up_read(&ni->runlist.lock);
1815 				if (unlikely(lcn < LCN_HOLE)) {
1816 					if (lcn == LCN_ENOMEM)
1817 						status = -ENOMEM;
1818 					else {
1819 						status = -EIO;
1820 						ntfs_error(vol->sb, "Cannot "
1821 							"perform write to "
1822 							"inode 0x%lx, "
1823 							"attribute type 0x%x, "
1824 							"because the attribute "
1825 							"is corrupt.",
1826 							vi->i_ino, (unsigned)
1827 							le32_to_cpu(ni->type));
1828 					}
1829 					break;
1830 				}
1831 				if (lcn == LCN_HOLE) {
1832 					start_idx = (pos & ~(s64)
1833 							vol->cluster_size_mask)
1834 							>> PAGE_SHIFT;
1835 					bytes = vol->cluster_size - (pos &
1836 							vol->cluster_size_mask);
1837 					do_pages = nr_pages;
1838 				}
1839 			}
1840 		}
1841 		if (bytes > iov_iter_count(i))
1842 			bytes = iov_iter_count(i);
1843 again:
1844 		/*
1845 		 * Bring in the user page(s) that we will copy from _first_.
1846 		 * Otherwise there is a nasty deadlock on copying from the same
1847 		 * page(s) as we are writing to, without it/them being marked
1848 		 * up-to-date.  Note, at present there is nothing to stop the
1849 		 * pages being swapped out between us bringing them into memory
1850 		 * and doing the actual copying.
1851 		 */
1852 		if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
1853 			status = -EFAULT;
1854 			break;
1855 		}
1856 		/* Get and lock @do_pages starting at index @start_idx. */
1857 		status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
1858 				pages, &cached_page);
1859 		if (unlikely(status))
1860 			break;
1861 		/*
1862 		 * For non-resident attributes, we need to fill any holes with
1863 		 * actual clusters and ensure all bufferes are mapped.  We also
1864 		 * need to bring uptodate any buffers that are only partially
1865 		 * being written to.
1866 		 */
1867 		if (NInoNonResident(ni)) {
1868 			status = ntfs_prepare_pages_for_non_resident_write(
1869 					pages, do_pages, pos, bytes);
1870 			if (unlikely(status)) {
1871 				do {
1872 					unlock_page(pages[--do_pages]);
1873 					put_page(pages[do_pages]);
1874 				} while (do_pages);
1875 				break;
1876 			}
1877 		}
1878 		u = (pos >> PAGE_SHIFT) - pages[0]->index;
1879 		copied = ntfs_copy_from_user_iter(pages + u, do_pages - u, ofs,
1880 					i, bytes);
1881 		ntfs_flush_dcache_pages(pages + u, do_pages - u);
1882 		status = 0;
1883 		if (likely(copied == bytes)) {
1884 			status = ntfs_commit_pages_after_write(pages, do_pages,
1885 					pos, bytes);
1886 			if (!status)
1887 				status = bytes;
1888 		}
1889 		do {
1890 			unlock_page(pages[--do_pages]);
1891 			put_page(pages[do_pages]);
1892 		} while (do_pages);
1893 		if (unlikely(status < 0))
1894 			break;
1895 		copied = status;
1896 		cond_resched();
1897 		if (unlikely(!copied)) {
1898 			size_t sc;
1899 
1900 			/*
1901 			 * We failed to copy anything.  Fall back to single
1902 			 * segment length write.
1903 			 *
1904 			 * This is needed to avoid possible livelock in the
1905 			 * case that all segments in the iov cannot be copied
1906 			 * at once without a pagefault.
1907 			 */
1908 			sc = iov_iter_single_seg_count(i);
1909 			if (bytes > sc)
1910 				bytes = sc;
1911 			goto again;
1912 		}
1913 		iov_iter_advance(i, copied);
1914 		pos += copied;
1915 		written += copied;
1916 		balance_dirty_pages_ratelimited(mapping);
1917 		if (fatal_signal_pending(current)) {
1918 			status = -EINTR;
1919 			break;
1920 		}
1921 	} while (iov_iter_count(i));
1922 	if (cached_page)
1923 		put_page(cached_page);
1924 	ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
1925 			written ? "written" : "status", (unsigned long)written,
1926 			(long)status);
1927 	return written ? written : status;
1928 }
1929 
1930 /**
1931  * ntfs_file_write_iter - simple wrapper for ntfs_file_write_iter_nolock()
1932  * @iocb:	IO state structure
1933  * @from:	iov_iter with data to write
1934  *
1935  * Basically the same as generic_file_write_iter() except that it ends up
1936  * up calling ntfs_perform_write() instead of generic_perform_write() and that
1937  * O_DIRECT is not implemented.
1938  */
ntfs_file_write_iter(struct kiocb * iocb,struct iov_iter * from)1939 static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1940 {
1941 	struct file *file = iocb->ki_filp;
1942 	struct inode *vi = file_inode(file);
1943 	ssize_t written = 0;
1944 	ssize_t err;
1945 
1946 	inode_lock(vi);
1947 	/* We can write back this queue in page reclaim. */
1948 	current->backing_dev_info = inode_to_bdi(vi);
1949 	err = ntfs_prepare_file_for_write(iocb, from);
1950 	if (iov_iter_count(from) && !err)
1951 		written = ntfs_perform_write(file, from, iocb->ki_pos);
1952 	current->backing_dev_info = NULL;
1953 	inode_unlock(vi);
1954 	iocb->ki_pos += written;
1955 	if (likely(written > 0))
1956 		written = generic_write_sync(iocb, written);
1957 	return written ? written : err;
1958 }
1959 
1960 /**
1961  * ntfs_file_fsync - sync a file to disk
1962  * @filp:	file to be synced
1963  * @datasync:	if non-zero only flush user data and not metadata
1964  *
1965  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
1966  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
1967  *
1968  * If @datasync is false, write the mft record and all associated extent mft
1969  * records as well as the $DATA attribute and then sync the block device.
1970  *
1971  * If @datasync is true and the attribute is non-resident, we skip the writing
1972  * of the mft record and all associated extent mft records (this might still
1973  * happen due to the write_inode_now() call).
1974  *
1975  * Also, if @datasync is true, we do not wait on the inode to be written out
1976  * but we always wait on the page cache pages to be written out.
1977  *
1978  * Locking: Caller must hold i_mutex on the inode.
1979  *
1980  * TODO: We should probably also write all attribute/index inodes associated
1981  * with this inode but since we have no simple way of getting to them we ignore
1982  * this problem for now.
1983  */
ntfs_file_fsync(struct file * filp,loff_t start,loff_t end,int datasync)1984 static int ntfs_file_fsync(struct file *filp, loff_t start, loff_t end,
1985 			   int datasync)
1986 {
1987 	struct inode *vi = filp->f_mapping->host;
1988 	int err, ret = 0;
1989 
1990 	ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
1991 
1992 	err = file_write_and_wait_range(filp, start, end);
1993 	if (err)
1994 		return err;
1995 	inode_lock(vi);
1996 
1997 	BUG_ON(S_ISDIR(vi->i_mode));
1998 	if (!datasync || !NInoNonResident(NTFS_I(vi)))
1999 		ret = __ntfs_write_inode(vi, 1);
2000 	write_inode_now(vi, !datasync);
2001 	/*
2002 	 * NOTE: If we were to use mapping->private_list (see ext2 and
2003 	 * fs/buffer.c) for dirty blocks then we could optimize the below to be
2004 	 * sync_mapping_buffers(vi->i_mapping).
2005 	 */
2006 	err = sync_blockdev(vi->i_sb->s_bdev);
2007 	if (unlikely(err && !ret))
2008 		ret = err;
2009 	if (likely(!ret))
2010 		ntfs_debug("Done.");
2011 	else
2012 		ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
2013 				"%u.", datasync ? "data" : "", vi->i_ino, -ret);
2014 	inode_unlock(vi);
2015 	return ret;
2016 }
2017 
2018 #endif /* NTFS_RW */
2019 
2020 const struct file_operations ntfs_file_ops = {
2021 	.llseek		= generic_file_llseek,
2022 	.read_iter	= generic_file_read_iter,
2023 #ifdef NTFS_RW
2024 	.write_iter	= ntfs_file_write_iter,
2025 	.fsync		= ntfs_file_fsync,
2026 #endif /* NTFS_RW */
2027 	.mmap		= generic_file_mmap,
2028 	.open		= ntfs_file_open,
2029 	.splice_read	= generic_file_splice_read,
2030 };
2031 
2032 const struct inode_operations ntfs_file_inode_ops = {
2033 #ifdef NTFS_RW
2034 	.setattr	= ntfs_setattr,
2035 #endif /* NTFS_RW */
2036 };
2037 
2038 const struct file_operations ntfs_empty_file_ops = {};
2039 
2040 const struct inode_operations ntfs_empty_inode_ops = {};
2041