xref: /openbmc/linux/fs/ntfs/attrib.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /**
2  * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
3  *
4  * Copyright (c) 2001-2005 Anton Altaparmakov
5  * Copyright (c) 2002 Richard Russon
6  *
7  * This program/include file is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as published
9  * by the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program/include file is distributed in the hope that it will be
13  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program (in the main directory of the Linux-NTFS
19  * distribution in the file COPYING); if not, write to the Free Software
20  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  */
22 
23 #include <linux/buffer_head.h>
24 #include <linux/sched.h>
25 #include <linux/swap.h>
26 #include <linux/writeback.h>
27 
28 #include "attrib.h"
29 #include "debug.h"
30 #include "layout.h"
31 #include "lcnalloc.h"
32 #include "malloc.h"
33 #include "mft.h"
34 #include "ntfs.h"
35 #include "types.h"
36 
37 /**
38  * ntfs_map_runlist_nolock - map (a part of) a runlist of an ntfs inode
39  * @ni:		ntfs inode for which to map (part of) a runlist
40  * @vcn:	map runlist part containing this vcn
41  * @ctx:	active attribute search context if present or NULL if not
42  *
43  * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
44  *
45  * If @ctx is specified, it is an active search context of @ni and its base mft
46  * record.  This is needed when ntfs_map_runlist_nolock() encounters unmapped
47  * runlist fragments and allows their mapping.  If you do not have the mft
48  * record mapped, you can specify @ctx as NULL and ntfs_map_runlist_nolock()
49  * will perform the necessary mapping and unmapping.
50  *
51  * Note, ntfs_map_runlist_nolock() saves the state of @ctx on entry and
52  * restores it before returning.  Thus, @ctx will be left pointing to the same
53  * attribute on return as on entry.  However, the actual pointers in @ctx may
54  * point to different memory locations on return, so you must remember to reset
55  * any cached pointers from the @ctx, i.e. after the call to
56  * ntfs_map_runlist_nolock(), you will probably want to do:
57  *	m = ctx->mrec;
58  *	a = ctx->attr;
59  * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
60  * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
61  *
62  * Return 0 on success and -errno on error.  There is one special error code
63  * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
64  * of bounds of the runlist.
65  *
66  * Note the runlist can be NULL after this function returns if @vcn is zero and
67  * the attribute has zero allocated size, i.e. there simply is no runlist.
68  *
69  * WARNING: If @ctx is supplied, regardless of whether success or failure is
70  *	    returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
71  *	    is no longer valid, i.e. you need to either call
72  *	    ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
73  *	    In that case PTR_ERR(@ctx->mrec) will give you the error code for
74  *	    why the mapping of the old inode failed.
75  *
76  * Locking: - The runlist described by @ni must be locked for writing on entry
77  *	      and is locked on return.  Note the runlist will be modified.
78  *	    - If @ctx is NULL, the base mft record of @ni must not be mapped on
79  *	      entry and it will be left unmapped on return.
80  *	    - If @ctx is not NULL, the base mft record must be mapped on entry
81  *	      and it will be left mapped on return.
82  */
83 int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn, ntfs_attr_search_ctx *ctx)
84 {
85 	VCN end_vcn;
86 	unsigned long flags;
87 	ntfs_inode *base_ni;
88 	MFT_RECORD *m;
89 	ATTR_RECORD *a;
90 	runlist_element *rl;
91 	struct page *put_this_page = NULL;
92 	int err = 0;
93 	BOOL ctx_is_temporary, ctx_needs_reset;
94 	ntfs_attr_search_ctx old_ctx = { NULL, };
95 
96 	ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
97 			(unsigned long long)vcn);
98 	if (!NInoAttr(ni))
99 		base_ni = ni;
100 	else
101 		base_ni = ni->ext.base_ntfs_ino;
102 	if (!ctx) {
103 		ctx_is_temporary = ctx_needs_reset = TRUE;
104 		m = map_mft_record(base_ni);
105 		if (IS_ERR(m))
106 			return PTR_ERR(m);
107 		ctx = ntfs_attr_get_search_ctx(base_ni, m);
108 		if (unlikely(!ctx)) {
109 			err = -ENOMEM;
110 			goto err_out;
111 		}
112 	} else {
113 		VCN allocated_size_vcn;
114 
115 		BUG_ON(IS_ERR(ctx->mrec));
116 		a = ctx->attr;
117 		BUG_ON(!a->non_resident);
118 		ctx_is_temporary = FALSE;
119 		end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
120 		read_lock_irqsave(&ni->size_lock, flags);
121 		allocated_size_vcn = ni->allocated_size >>
122 				ni->vol->cluster_size_bits;
123 		read_unlock_irqrestore(&ni->size_lock, flags);
124 		if (!a->data.non_resident.lowest_vcn && end_vcn <= 0)
125 			end_vcn = allocated_size_vcn - 1;
126 		/*
127 		 * If we already have the attribute extent containing @vcn in
128 		 * @ctx, no need to look it up again.  We slightly cheat in
129 		 * that if vcn exceeds the allocated size, we will refuse to
130 		 * map the runlist below, so there is definitely no need to get
131 		 * the right attribute extent.
132 		 */
133 		if (vcn >= allocated_size_vcn || (a->type == ni->type &&
134 				a->name_length == ni->name_len &&
135 				!memcmp((u8*)a + le16_to_cpu(a->name_offset),
136 				ni->name, ni->name_len) &&
137 				sle64_to_cpu(a->data.non_resident.lowest_vcn)
138 				<= vcn && end_vcn >= vcn))
139 			ctx_needs_reset = FALSE;
140 		else {
141 			/* Save the old search context. */
142 			old_ctx = *ctx;
143 			/*
144 			 * If the currently mapped (extent) inode is not the
145 			 * base inode we will unmap it when we reinitialize the
146 			 * search context which means we need to get a
147 			 * reference to the page containing the mapped mft
148 			 * record so we do not accidentally drop changes to the
149 			 * mft record when it has not been marked dirty yet.
150 			 */
151 			if (old_ctx.base_ntfs_ino && old_ctx.ntfs_ino !=
152 					old_ctx.base_ntfs_ino) {
153 				put_this_page = old_ctx.ntfs_ino->page;
154 				page_cache_get(put_this_page);
155 			}
156 			/*
157 			 * Reinitialize the search context so we can lookup the
158 			 * needed attribute extent.
159 			 */
160 			ntfs_attr_reinit_search_ctx(ctx);
161 			ctx_needs_reset = TRUE;
162 		}
163 	}
164 	if (ctx_needs_reset) {
165 		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
166 				CASE_SENSITIVE, vcn, NULL, 0, ctx);
167 		if (unlikely(err)) {
168 			if (err == -ENOENT)
169 				err = -EIO;
170 			goto err_out;
171 		}
172 		BUG_ON(!ctx->attr->non_resident);
173 	}
174 	a = ctx->attr;
175 	/*
176 	 * Only decompress the mapping pairs if @vcn is inside it.  Otherwise
177 	 * we get into problems when we try to map an out of bounds vcn because
178 	 * we then try to map the already mapped runlist fragment and
179 	 * ntfs_mapping_pairs_decompress() fails.
180 	 */
181 	end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;
182 	if (!a->data.non_resident.lowest_vcn && end_vcn == 1)
183 		end_vcn = sle64_to_cpu(a->data.non_resident.allocated_size) >>
184 				ni->vol->cluster_size_bits;
185 	if (unlikely(vcn >= end_vcn)) {
186 		err = -ENOENT;
187 		goto err_out;
188 	}
189 	rl = ntfs_mapping_pairs_decompress(ni->vol, a, ni->runlist.rl);
190 	if (IS_ERR(rl))
191 		err = PTR_ERR(rl);
192 	else
193 		ni->runlist.rl = rl;
194 err_out:
195 	if (ctx_is_temporary) {
196 		if (likely(ctx))
197 			ntfs_attr_put_search_ctx(ctx);
198 		unmap_mft_record(base_ni);
199 	} else if (ctx_needs_reset) {
200 		/*
201 		 * If there is no attribute list, restoring the search context
202 		 * is acomplished simply by copying the saved context back over
203 		 * the caller supplied context.  If there is an attribute list,
204 		 * things are more complicated as we need to deal with mapping
205 		 * of mft records and resulting potential changes in pointers.
206 		 */
207 		if (NInoAttrList(base_ni)) {
208 			/*
209 			 * If the currently mapped (extent) inode is not the
210 			 * one we had before, we need to unmap it and map the
211 			 * old one.
212 			 */
213 			if (ctx->ntfs_ino != old_ctx.ntfs_ino) {
214 				/*
215 				 * If the currently mapped inode is not the
216 				 * base inode, unmap it.
217 				 */
218 				if (ctx->base_ntfs_ino && ctx->ntfs_ino !=
219 						ctx->base_ntfs_ino) {
220 					unmap_extent_mft_record(ctx->ntfs_ino);
221 					ctx->mrec = ctx->base_mrec;
222 					BUG_ON(!ctx->mrec);
223 				}
224 				/*
225 				 * If the old mapped inode is not the base
226 				 * inode, map it.
227 				 */
228 				if (old_ctx.base_ntfs_ino &&
229 						old_ctx.ntfs_ino !=
230 						old_ctx.base_ntfs_ino) {
231 retry_map:
232 					ctx->mrec = map_mft_record(
233 							old_ctx.ntfs_ino);
234 					/*
235 					 * Something bad has happened.  If out
236 					 * of memory retry till it succeeds.
237 					 * Any other errors are fatal and we
238 					 * return the error code in ctx->mrec.
239 					 * Let the caller deal with it...  We
240 					 * just need to fudge things so the
241 					 * caller can reinit and/or put the
242 					 * search context safely.
243 					 */
244 					if (IS_ERR(ctx->mrec)) {
245 						if (PTR_ERR(ctx->mrec) ==
246 								-ENOMEM) {
247 							schedule();
248 							goto retry_map;
249 						} else
250 							old_ctx.ntfs_ino =
251 								old_ctx.
252 								base_ntfs_ino;
253 					}
254 				}
255 			}
256 			/* Update the changed pointers in the saved context. */
257 			if (ctx->mrec != old_ctx.mrec) {
258 				if (!IS_ERR(ctx->mrec))
259 					old_ctx.attr = (ATTR_RECORD*)(
260 							(u8*)ctx->mrec +
261 							((u8*)old_ctx.attr -
262 							(u8*)old_ctx.mrec));
263 				old_ctx.mrec = ctx->mrec;
264 			}
265 		}
266 		/* Restore the search context to the saved one. */
267 		*ctx = old_ctx;
268 		/*
269 		 * We drop the reference on the page we took earlier.  In the
270 		 * case that IS_ERR(ctx->mrec) is true this means we might lose
271 		 * some changes to the mft record that had been made between
272 		 * the last time it was marked dirty/written out and now.  This
273 		 * at this stage is not a problem as the mapping error is fatal
274 		 * enough that the mft record cannot be written out anyway and
275 		 * the caller is very likely to shutdown the whole inode
276 		 * immediately and mark the volume dirty for chkdsk to pick up
277 		 * the pieces anyway.
278 		 */
279 		if (put_this_page)
280 			page_cache_release(put_this_page);
281 	}
282 	return err;
283 }
284 
285 /**
286  * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
287  * @ni:		ntfs inode for which to map (part of) a runlist
288  * @vcn:	map runlist part containing this vcn
289  *
290  * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
291  *
292  * Return 0 on success and -errno on error.  There is one special error code
293  * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
294  * of bounds of the runlist.
295  *
296  * Locking: - The runlist must be unlocked on entry and is unlocked on return.
297  *	    - This function takes the runlist lock for writing and may modify
298  *	      the runlist.
299  */
300 int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
301 {
302 	int err = 0;
303 
304 	down_write(&ni->runlist.lock);
305 	/* Make sure someone else didn't do the work while we were sleeping. */
306 	if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
307 			LCN_RL_NOT_MAPPED))
308 		err = ntfs_map_runlist_nolock(ni, vcn, NULL);
309 	up_write(&ni->runlist.lock);
310 	return err;
311 }
312 
313 /**
314  * ntfs_attr_vcn_to_lcn_nolock - convert a vcn into a lcn given an ntfs inode
315  * @ni:			ntfs inode of the attribute whose runlist to search
316  * @vcn:		vcn to convert
317  * @write_locked:	true if the runlist is locked for writing
318  *
319  * Find the virtual cluster number @vcn in the runlist of the ntfs attribute
320  * described by the ntfs inode @ni and return the corresponding logical cluster
321  * number (lcn).
322  *
323  * If the @vcn is not mapped yet, the attempt is made to map the attribute
324  * extent containing the @vcn and the vcn to lcn conversion is retried.
325  *
326  * If @write_locked is true the caller has locked the runlist for writing and
327  * if false for reading.
328  *
329  * Since lcns must be >= 0, we use negative return codes with special meaning:
330  *
331  * Return code	Meaning / Description
332  * ==========================================
333  *  LCN_HOLE	Hole / not allocated on disk.
334  *  LCN_ENOENT	There is no such vcn in the runlist, i.e. @vcn is out of bounds.
335  *  LCN_ENOMEM	Not enough memory to map runlist.
336  *  LCN_EIO	Critical error (runlist/file is corrupt, i/o error, etc).
337  *
338  * Locking: - The runlist must be locked on entry and is left locked on return.
339  *	    - If @write_locked is FALSE, i.e. the runlist is locked for reading,
340  *	      the lock may be dropped inside the function so you cannot rely on
341  *	      the runlist still being the same when this function returns.
342  */
343 LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
344 		const BOOL write_locked)
345 {
346 	LCN lcn;
347 	unsigned long flags;
348 	BOOL is_retry = FALSE;
349 
350 	ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
351 			ni->mft_no, (unsigned long long)vcn,
352 			write_locked ? "write" : "read");
353 	BUG_ON(!ni);
354 	BUG_ON(!NInoNonResident(ni));
355 	BUG_ON(vcn < 0);
356 	if (!ni->runlist.rl) {
357 		read_lock_irqsave(&ni->size_lock, flags);
358 		if (!ni->allocated_size) {
359 			read_unlock_irqrestore(&ni->size_lock, flags);
360 			return LCN_ENOENT;
361 		}
362 		read_unlock_irqrestore(&ni->size_lock, flags);
363 	}
364 retry_remap:
365 	/* Convert vcn to lcn.  If that fails map the runlist and retry once. */
366 	lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
367 	if (likely(lcn >= LCN_HOLE)) {
368 		ntfs_debug("Done, lcn 0x%llx.", (long long)lcn);
369 		return lcn;
370 	}
371 	if (lcn != LCN_RL_NOT_MAPPED) {
372 		if (lcn != LCN_ENOENT)
373 			lcn = LCN_EIO;
374 	} else if (!is_retry) {
375 		int err;
376 
377 		if (!write_locked) {
378 			up_read(&ni->runlist.lock);
379 			down_write(&ni->runlist.lock);
380 			if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
381 					LCN_RL_NOT_MAPPED)) {
382 				up_write(&ni->runlist.lock);
383 				down_read(&ni->runlist.lock);
384 				goto retry_remap;
385 			}
386 		}
387 		err = ntfs_map_runlist_nolock(ni, vcn, NULL);
388 		if (!write_locked) {
389 			up_write(&ni->runlist.lock);
390 			down_read(&ni->runlist.lock);
391 		}
392 		if (likely(!err)) {
393 			is_retry = TRUE;
394 			goto retry_remap;
395 		}
396 		if (err == -ENOENT)
397 			lcn = LCN_ENOENT;
398 		else if (err == -ENOMEM)
399 			lcn = LCN_ENOMEM;
400 		else
401 			lcn = LCN_EIO;
402 	}
403 	if (lcn != LCN_ENOENT)
404 		ntfs_error(ni->vol->sb, "Failed with error code %lli.",
405 				(long long)lcn);
406 	return lcn;
407 }
408 
409 /**
410  * ntfs_attr_find_vcn_nolock - find a vcn in the runlist of an ntfs inode
411  * @ni:		ntfs inode describing the runlist to search
412  * @vcn:	vcn to find
413  * @ctx:	active attribute search context if present or NULL if not
414  *
415  * Find the virtual cluster number @vcn in the runlist described by the ntfs
416  * inode @ni and return the address of the runlist element containing the @vcn.
417  *
418  * If the @vcn is not mapped yet, the attempt is made to map the attribute
419  * extent containing the @vcn and the vcn to lcn conversion is retried.
420  *
421  * If @ctx is specified, it is an active search context of @ni and its base mft
422  * record.  This is needed when ntfs_attr_find_vcn_nolock() encounters unmapped
423  * runlist fragments and allows their mapping.  If you do not have the mft
424  * record mapped, you can specify @ctx as NULL and ntfs_attr_find_vcn_nolock()
425  * will perform the necessary mapping and unmapping.
426  *
427  * Note, ntfs_attr_find_vcn_nolock() saves the state of @ctx on entry and
428  * restores it before returning.  Thus, @ctx will be left pointing to the same
429  * attribute on return as on entry.  However, the actual pointers in @ctx may
430  * point to different memory locations on return, so you must remember to reset
431  * any cached pointers from the @ctx, i.e. after the call to
432  * ntfs_attr_find_vcn_nolock(), you will probably want to do:
433  *	m = ctx->mrec;
434  *	a = ctx->attr;
435  * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
436  * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
437  * Note you need to distinguish between the lcn of the returned runlist element
438  * being >= 0 and LCN_HOLE.  In the later case you have to return zeroes on
439  * read and allocate clusters on write.
440  *
441  * Return the runlist element containing the @vcn on success and
442  * ERR_PTR(-errno) on error.  You need to test the return value with IS_ERR()
443  * to decide if the return is success or failure and PTR_ERR() to get to the
444  * error code if IS_ERR() is true.
445  *
446  * The possible error return codes are:
447  *	-ENOENT - No such vcn in the runlist, i.e. @vcn is out of bounds.
448  *	-ENOMEM - Not enough memory to map runlist.
449  *	-EIO	- Critical error (runlist/file is corrupt, i/o error, etc).
450  *
451  * WARNING: If @ctx is supplied, regardless of whether success or failure is
452  *	    returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
453  *	    is no longer valid, i.e. you need to either call
454  *	    ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
455  *	    In that case PTR_ERR(@ctx->mrec) will give you the error code for
456  *	    why the mapping of the old inode failed.
457  *
458  * Locking: - The runlist described by @ni must be locked for writing on entry
459  *	      and is locked on return.  Note the runlist may be modified when
460  *	      needed runlist fragments need to be mapped.
461  *	    - If @ctx is NULL, the base mft record of @ni must not be mapped on
462  *	      entry and it will be left unmapped on return.
463  *	    - If @ctx is not NULL, the base mft record must be mapped on entry
464  *	      and it will be left mapped on return.
465  */
466 runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
467 		ntfs_attr_search_ctx *ctx)
468 {
469 	unsigned long flags;
470 	runlist_element *rl;
471 	int err = 0;
472 	BOOL is_retry = FALSE;
473 
474 	ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, with%s ctx.",
475 			ni->mft_no, (unsigned long long)vcn, ctx ? "" : "out");
476 	BUG_ON(!ni);
477 	BUG_ON(!NInoNonResident(ni));
478 	BUG_ON(vcn < 0);
479 	if (!ni->runlist.rl) {
480 		read_lock_irqsave(&ni->size_lock, flags);
481 		if (!ni->allocated_size) {
482 			read_unlock_irqrestore(&ni->size_lock, flags);
483 			return ERR_PTR(-ENOENT);
484 		}
485 		read_unlock_irqrestore(&ni->size_lock, flags);
486 	}
487 retry_remap:
488 	rl = ni->runlist.rl;
489 	if (likely(rl && vcn >= rl[0].vcn)) {
490 		while (likely(rl->length)) {
491 			if (unlikely(vcn < rl[1].vcn)) {
492 				if (likely(rl->lcn >= LCN_HOLE)) {
493 					ntfs_debug("Done.");
494 					return rl;
495 				}
496 				break;
497 			}
498 			rl++;
499 		}
500 		if (likely(rl->lcn != LCN_RL_NOT_MAPPED)) {
501 			if (likely(rl->lcn == LCN_ENOENT))
502 				err = -ENOENT;
503 			else
504 				err = -EIO;
505 		}
506 	}
507 	if (!err && !is_retry) {
508 		/*
509 		 * If the search context is invalid we cannot map the unmapped
510 		 * region.
511 		 */
512 		if (IS_ERR(ctx->mrec))
513 			err = PTR_ERR(ctx->mrec);
514 		else {
515 			/*
516 			 * The @vcn is in an unmapped region, map the runlist
517 			 * and retry.
518 			 */
519 			err = ntfs_map_runlist_nolock(ni, vcn, ctx);
520 			if (likely(!err)) {
521 				is_retry = TRUE;
522 				goto retry_remap;
523 			}
524 		}
525 		if (err == -EINVAL)
526 			err = -EIO;
527 	} else if (!err)
528 		err = -EIO;
529 	if (err != -ENOENT)
530 		ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
531 	return ERR_PTR(err);
532 }
533 
534 /**
535  * ntfs_attr_find - find (next) attribute in mft record
536  * @type:	attribute type to find
537  * @name:	attribute name to find (optional, i.e. NULL means don't care)
538  * @name_len:	attribute name length (only needed if @name present)
539  * @ic:		IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
540  * @val:	attribute value to find (optional, resident attributes only)
541  * @val_len:	attribute value length
542  * @ctx:	search context with mft record and attribute to search from
543  *
544  * You should not need to call this function directly.  Use ntfs_attr_lookup()
545  * instead.
546  *
547  * ntfs_attr_find() takes a search context @ctx as parameter and searches the
548  * mft record specified by @ctx->mrec, beginning at @ctx->attr, for an
549  * attribute of @type, optionally @name and @val.
550  *
551  * If the attribute is found, ntfs_attr_find() returns 0 and @ctx->attr will
552  * point to the found attribute.
553  *
554  * If the attribute is not found, ntfs_attr_find() returns -ENOENT and
555  * @ctx->attr will point to the attribute before which the attribute being
556  * searched for would need to be inserted if such an action were to be desired.
557  *
558  * On actual error, ntfs_attr_find() returns -EIO.  In this case @ctx->attr is
559  * undefined and in particular do not rely on it not changing.
560  *
561  * If @ctx->is_first is TRUE, the search begins with @ctx->attr itself.  If it
562  * is FALSE, the search begins after @ctx->attr.
563  *
564  * If @ic is IGNORE_CASE, the @name comparisson is not case sensitive and
565  * @ctx->ntfs_ino must be set to the ntfs inode to which the mft record
566  * @ctx->mrec belongs.  This is so we can get at the ntfs volume and hence at
567  * the upcase table.  If @ic is CASE_SENSITIVE, the comparison is case
568  * sensitive.  When @name is present, @name_len is the @name length in Unicode
569  * characters.
570  *
571  * If @name is not present (NULL), we assume that the unnamed attribute is
572  * being searched for.
573  *
574  * Finally, the resident attribute value @val is looked for, if present.  If
575  * @val is not present (NULL), @val_len is ignored.
576  *
577  * ntfs_attr_find() only searches the specified mft record and it ignores the
578  * presence of an attribute list attribute (unless it is the one being searched
579  * for, obviously).  If you need to take attribute lists into consideration,
580  * use ntfs_attr_lookup() instead (see below).  This also means that you cannot
581  * use ntfs_attr_find() to search for extent records of non-resident
582  * attributes, as extents with lowest_vcn != 0 are usually described by the
583  * attribute list attribute only. - Note that it is possible that the first
584  * extent is only in the attribute list while the last extent is in the base
585  * mft record, so do not rely on being able to find the first extent in the
586  * base mft record.
587  *
588  * Warning: Never use @val when looking for attribute types which can be
589  *	    non-resident as this most likely will result in a crash!
590  */
591 static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
592 		const u32 name_len, const IGNORE_CASE_BOOL ic,
593 		const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
594 {
595 	ATTR_RECORD *a;
596 	ntfs_volume *vol = ctx->ntfs_ino->vol;
597 	ntfschar *upcase = vol->upcase;
598 	u32 upcase_len = vol->upcase_len;
599 
600 	/*
601 	 * Iterate over attributes in mft record starting at @ctx->attr, or the
602 	 * attribute following that, if @ctx->is_first is TRUE.
603 	 */
604 	if (ctx->is_first) {
605 		a = ctx->attr;
606 		ctx->is_first = FALSE;
607 	} else
608 		a = (ATTR_RECORD*)((u8*)ctx->attr +
609 				le32_to_cpu(ctx->attr->length));
610 	for (;;	a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) {
611 		if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
612 				le32_to_cpu(ctx->mrec->bytes_allocated))
613 			break;
614 		ctx->attr = a;
615 		if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||
616 				a->type == AT_END))
617 			return -ENOENT;
618 		if (unlikely(!a->length))
619 			break;
620 		if (a->type != type)
621 			continue;
622 		/*
623 		 * If @name is present, compare the two names.  If @name is
624 		 * missing, assume we want an unnamed attribute.
625 		 */
626 		if (!name) {
627 			/* The search failed if the found attribute is named. */
628 			if (a->name_length)
629 				return -ENOENT;
630 		} else if (!ntfs_are_names_equal(name, name_len,
631 			    (ntfschar*)((u8*)a + le16_to_cpu(a->name_offset)),
632 			    a->name_length, ic, upcase, upcase_len)) {
633 			register int rc;
634 
635 			rc = ntfs_collate_names(name, name_len,
636 					(ntfschar*)((u8*)a +
637 					le16_to_cpu(a->name_offset)),
638 					a->name_length, 1, IGNORE_CASE,
639 					upcase, upcase_len);
640 			/*
641 			 * If @name collates before a->name, there is no
642 			 * matching attribute.
643 			 */
644 			if (rc == -1)
645 				return -ENOENT;
646 			/* If the strings are not equal, continue search. */
647 			if (rc)
648 				continue;
649 			rc = ntfs_collate_names(name, name_len,
650 					(ntfschar*)((u8*)a +
651 					le16_to_cpu(a->name_offset)),
652 					a->name_length, 1, CASE_SENSITIVE,
653 					upcase, upcase_len);
654 			if (rc == -1)
655 				return -ENOENT;
656 			if (rc)
657 				continue;
658 		}
659 		/*
660 		 * The names match or @name not present and attribute is
661 		 * unnamed.  If no @val specified, we have found the attribute
662 		 * and are done.
663 		 */
664 		if (!val)
665 			return 0;
666 		/* @val is present; compare values. */
667 		else {
668 			register int rc;
669 
670 			rc = memcmp(val, (u8*)a + le16_to_cpu(
671 					a->data.resident.value_offset),
672 					min_t(u32, val_len, le32_to_cpu(
673 					a->data.resident.value_length)));
674 			/*
675 			 * If @val collates before the current attribute's
676 			 * value, there is no matching attribute.
677 			 */
678 			if (!rc) {
679 				register u32 avl;
680 
681 				avl = le32_to_cpu(
682 						a->data.resident.value_length);
683 				if (val_len == avl)
684 					return 0;
685 				if (val_len < avl)
686 					return -ENOENT;
687 			} else if (rc < 0)
688 				return -ENOENT;
689 		}
690 	}
691 	ntfs_error(vol->sb, "Inode is corrupt.  Run chkdsk.");
692 	NVolSetErrors(vol);
693 	return -EIO;
694 }
695 
696 /**
697  * load_attribute_list - load an attribute list into memory
698  * @vol:		ntfs volume from which to read
699  * @runlist:		runlist of the attribute list
700  * @al_start:		destination buffer
701  * @size:		size of the destination buffer in bytes
702  * @initialized_size:	initialized size of the attribute list
703  *
704  * Walk the runlist @runlist and load all clusters from it copying them into
705  * the linear buffer @al. The maximum number of bytes copied to @al is @size
706  * bytes. Note, @size does not need to be a multiple of the cluster size. If
707  * @initialized_size is less than @size, the region in @al between
708  * @initialized_size and @size will be zeroed and not read from disk.
709  *
710  * Return 0 on success or -errno on error.
711  */
712 int load_attribute_list(ntfs_volume *vol, runlist *runlist, u8 *al_start,
713 		const s64 size, const s64 initialized_size)
714 {
715 	LCN lcn;
716 	u8 *al = al_start;
717 	u8 *al_end = al + initialized_size;
718 	runlist_element *rl;
719 	struct buffer_head *bh;
720 	struct super_block *sb;
721 	unsigned long block_size;
722 	unsigned long block, max_block;
723 	int err = 0;
724 	unsigned char block_size_bits;
725 
726 	ntfs_debug("Entering.");
727 	if (!vol || !runlist || !al || size <= 0 || initialized_size < 0 ||
728 			initialized_size > size)
729 		return -EINVAL;
730 	if (!initialized_size) {
731 		memset(al, 0, size);
732 		return 0;
733 	}
734 	sb = vol->sb;
735 	block_size = sb->s_blocksize;
736 	block_size_bits = sb->s_blocksize_bits;
737 	down_read(&runlist->lock);
738 	rl = runlist->rl;
739 	if (!rl) {
740 		ntfs_error(sb, "Cannot read attribute list since runlist is "
741 				"missing.");
742 		goto err_out;
743 	}
744 	/* Read all clusters specified by the runlist one run at a time. */
745 	while (rl->length) {
746 		lcn = ntfs_rl_vcn_to_lcn(rl, rl->vcn);
747 		ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
748 				(unsigned long long)rl->vcn,
749 				(unsigned long long)lcn);
750 		/* The attribute list cannot be sparse. */
751 		if (lcn < 0) {
752 			ntfs_error(sb, "ntfs_rl_vcn_to_lcn() failed.  Cannot "
753 					"read attribute list.");
754 			goto err_out;
755 		}
756 		block = lcn << vol->cluster_size_bits >> block_size_bits;
757 		/* Read the run from device in chunks of block_size bytes. */
758 		max_block = block + (rl->length << vol->cluster_size_bits >>
759 				block_size_bits);
760 		ntfs_debug("max_block = 0x%lx.", max_block);
761 		do {
762 			ntfs_debug("Reading block = 0x%lx.", block);
763 			bh = sb_bread(sb, block);
764 			if (!bh) {
765 				ntfs_error(sb, "sb_bread() failed. Cannot "
766 						"read attribute list.");
767 				goto err_out;
768 			}
769 			if (al + block_size >= al_end)
770 				goto do_final;
771 			memcpy(al, bh->b_data, block_size);
772 			brelse(bh);
773 			al += block_size;
774 		} while (++block < max_block);
775 		rl++;
776 	}
777 	if (initialized_size < size) {
778 initialize:
779 		memset(al_start + initialized_size, 0, size - initialized_size);
780 	}
781 done:
782 	up_read(&runlist->lock);
783 	return err;
784 do_final:
785 	if (al < al_end) {
786 		/*
787 		 * Partial block.
788 		 *
789 		 * Note: The attribute list can be smaller than its allocation
790 		 * by multiple clusters.  This has been encountered by at least
791 		 * two people running Windows XP, thus we cannot do any
792 		 * truncation sanity checking here. (AIA)
793 		 */
794 		memcpy(al, bh->b_data, al_end - al);
795 		brelse(bh);
796 		if (initialized_size < size)
797 			goto initialize;
798 		goto done;
799 	}
800 	brelse(bh);
801 	/* Real overflow! */
802 	ntfs_error(sb, "Attribute list buffer overflow. Read attribute list "
803 			"is truncated.");
804 err_out:
805 	err = -EIO;
806 	goto done;
807 }
808 
809 /**
810  * ntfs_external_attr_find - find an attribute in the attribute list of an inode
811  * @type:	attribute type to find
812  * @name:	attribute name to find (optional, i.e. NULL means don't care)
813  * @name_len:	attribute name length (only needed if @name present)
814  * @ic:		IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
815  * @lowest_vcn:	lowest vcn to find (optional, non-resident attributes only)
816  * @val:	attribute value to find (optional, resident attributes only)
817  * @val_len:	attribute value length
818  * @ctx:	search context with mft record and attribute to search from
819  *
820  * You should not need to call this function directly.  Use ntfs_attr_lookup()
821  * instead.
822  *
823  * Find an attribute by searching the attribute list for the corresponding
824  * attribute list entry.  Having found the entry, map the mft record if the
825  * attribute is in a different mft record/inode, ntfs_attr_find() the attribute
826  * in there and return it.
827  *
828  * On first search @ctx->ntfs_ino must be the base mft record and @ctx must
829  * have been obtained from a call to ntfs_attr_get_search_ctx().  On subsequent
830  * calls @ctx->ntfs_ino can be any extent inode, too (@ctx->base_ntfs_ino is
831  * then the base inode).
832  *
833  * After finishing with the attribute/mft record you need to call
834  * ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
835  * mapped inodes, etc).
836  *
837  * If the attribute is found, ntfs_external_attr_find() returns 0 and
838  * @ctx->attr will point to the found attribute.  @ctx->mrec will point to the
839  * mft record in which @ctx->attr is located and @ctx->al_entry will point to
840  * the attribute list entry for the attribute.
841  *
842  * If the attribute is not found, ntfs_external_attr_find() returns -ENOENT and
843  * @ctx->attr will point to the attribute in the base mft record before which
844  * the attribute being searched for would need to be inserted if such an action
845  * were to be desired.  @ctx->mrec will point to the mft record in which
846  * @ctx->attr is located and @ctx->al_entry will point to the attribute list
847  * entry of the attribute before which the attribute being searched for would
848  * need to be inserted if such an action were to be desired.
849  *
850  * Thus to insert the not found attribute, one wants to add the attribute to
851  * @ctx->mrec (the base mft record) and if there is not enough space, the
852  * attribute should be placed in a newly allocated extent mft record.  The
853  * attribute list entry for the inserted attribute should be inserted in the
854  * attribute list attribute at @ctx->al_entry.
855  *
856  * On actual error, ntfs_external_attr_find() returns -EIO.  In this case
857  * @ctx->attr is undefined and in particular do not rely on it not changing.
858  */
859 static int ntfs_external_attr_find(const ATTR_TYPE type,
860 		const ntfschar *name, const u32 name_len,
861 		const IGNORE_CASE_BOOL ic, const VCN lowest_vcn,
862 		const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
863 {
864 	ntfs_inode *base_ni, *ni;
865 	ntfs_volume *vol;
866 	ATTR_LIST_ENTRY *al_entry, *next_al_entry;
867 	u8 *al_start, *al_end;
868 	ATTR_RECORD *a;
869 	ntfschar *al_name;
870 	u32 al_name_len;
871 	int err = 0;
872 	static const char *es = " Unmount and run chkdsk.";
873 
874 	ni = ctx->ntfs_ino;
875 	base_ni = ctx->base_ntfs_ino;
876 	ntfs_debug("Entering for inode 0x%lx, type 0x%x.", ni->mft_no, type);
877 	if (!base_ni) {
878 		/* First call happens with the base mft record. */
879 		base_ni = ctx->base_ntfs_ino = ctx->ntfs_ino;
880 		ctx->base_mrec = ctx->mrec;
881 	}
882 	if (ni == base_ni)
883 		ctx->base_attr = ctx->attr;
884 	if (type == AT_END)
885 		goto not_found;
886 	vol = base_ni->vol;
887 	al_start = base_ni->attr_list;
888 	al_end = al_start + base_ni->attr_list_size;
889 	if (!ctx->al_entry)
890 		ctx->al_entry = (ATTR_LIST_ENTRY*)al_start;
891 	/*
892 	 * Iterate over entries in attribute list starting at @ctx->al_entry,
893 	 * or the entry following that, if @ctx->is_first is TRUE.
894 	 */
895 	if (ctx->is_first) {
896 		al_entry = ctx->al_entry;
897 		ctx->is_first = FALSE;
898 	} else
899 		al_entry = (ATTR_LIST_ENTRY*)((u8*)ctx->al_entry +
900 				le16_to_cpu(ctx->al_entry->length));
901 	for (;; al_entry = next_al_entry) {
902 		/* Out of bounds check. */
903 		if ((u8*)al_entry < base_ni->attr_list ||
904 				(u8*)al_entry > al_end)
905 			break;	/* Inode is corrupt. */
906 		ctx->al_entry = al_entry;
907 		/* Catch the end of the attribute list. */
908 		if ((u8*)al_entry == al_end)
909 			goto not_found;
910 		if (!al_entry->length)
911 			break;
912 		if ((u8*)al_entry + 6 > al_end || (u8*)al_entry +
913 				le16_to_cpu(al_entry->length) > al_end)
914 			break;
915 		next_al_entry = (ATTR_LIST_ENTRY*)((u8*)al_entry +
916 				le16_to_cpu(al_entry->length));
917 		if (le32_to_cpu(al_entry->type) > le32_to_cpu(type))
918 			goto not_found;
919 		if (type != al_entry->type)
920 			continue;
921 		/*
922 		 * If @name is present, compare the two names.  If @name is
923 		 * missing, assume we want an unnamed attribute.
924 		 */
925 		al_name_len = al_entry->name_length;
926 		al_name = (ntfschar*)((u8*)al_entry + al_entry->name_offset);
927 		if (!name) {
928 			if (al_name_len)
929 				goto not_found;
930 		} else if (!ntfs_are_names_equal(al_name, al_name_len, name,
931 				name_len, ic, vol->upcase, vol->upcase_len)) {
932 			register int rc;
933 
934 			rc = ntfs_collate_names(name, name_len, al_name,
935 					al_name_len, 1, IGNORE_CASE,
936 					vol->upcase, vol->upcase_len);
937 			/*
938 			 * If @name collates before al_name, there is no
939 			 * matching attribute.
940 			 */
941 			if (rc == -1)
942 				goto not_found;
943 			/* If the strings are not equal, continue search. */
944 			if (rc)
945 				continue;
946 			/*
947 			 * FIXME: Reverse engineering showed 0, IGNORE_CASE but
948 			 * that is inconsistent with ntfs_attr_find().  The
949 			 * subsequent rc checks were also different.  Perhaps I
950 			 * made a mistake in one of the two.  Need to recheck
951 			 * which is correct or at least see what is going on...
952 			 * (AIA)
953 			 */
954 			rc = ntfs_collate_names(name, name_len, al_name,
955 					al_name_len, 1, CASE_SENSITIVE,
956 					vol->upcase, vol->upcase_len);
957 			if (rc == -1)
958 				goto not_found;
959 			if (rc)
960 				continue;
961 		}
962 		/*
963 		 * The names match or @name not present and attribute is
964 		 * unnamed.  Now check @lowest_vcn.  Continue search if the
965 		 * next attribute list entry still fits @lowest_vcn.  Otherwise
966 		 * we have reached the right one or the search has failed.
967 		 */
968 		if (lowest_vcn && (u8*)next_al_entry >= al_start	    &&
969 				(u8*)next_al_entry + 6 < al_end		    &&
970 				(u8*)next_al_entry + le16_to_cpu(
971 					next_al_entry->length) <= al_end    &&
972 				sle64_to_cpu(next_al_entry->lowest_vcn) <=
973 					lowest_vcn			    &&
974 				next_al_entry->type == al_entry->type	    &&
975 				next_al_entry->name_length == al_name_len   &&
976 				ntfs_are_names_equal((ntfschar*)((u8*)
977 					next_al_entry +
978 					next_al_entry->name_offset),
979 					next_al_entry->name_length,
980 					al_name, al_name_len, CASE_SENSITIVE,
981 					vol->upcase, vol->upcase_len))
982 			continue;
983 		if (MREF_LE(al_entry->mft_reference) == ni->mft_no) {
984 			if (MSEQNO_LE(al_entry->mft_reference) != ni->seq_no) {
985 				ntfs_error(vol->sb, "Found stale mft "
986 						"reference in attribute list "
987 						"of base inode 0x%lx.%s",
988 						base_ni->mft_no, es);
989 				err = -EIO;
990 				break;
991 			}
992 		} else { /* Mft references do not match. */
993 			/* If there is a mapped record unmap it first. */
994 			if (ni != base_ni)
995 				unmap_extent_mft_record(ni);
996 			/* Do we want the base record back? */
997 			if (MREF_LE(al_entry->mft_reference) ==
998 					base_ni->mft_no) {
999 				ni = ctx->ntfs_ino = base_ni;
1000 				ctx->mrec = ctx->base_mrec;
1001 			} else {
1002 				/* We want an extent record. */
1003 				ctx->mrec = map_extent_mft_record(base_ni,
1004 						le64_to_cpu(
1005 						al_entry->mft_reference), &ni);
1006 				if (IS_ERR(ctx->mrec)) {
1007 					ntfs_error(vol->sb, "Failed to map "
1008 							"extent mft record "
1009 							"0x%lx of base inode "
1010 							"0x%lx.%s",
1011 							MREF_LE(al_entry->
1012 							mft_reference),
1013 							base_ni->mft_no, es);
1014 					err = PTR_ERR(ctx->mrec);
1015 					if (err == -ENOENT)
1016 						err = -EIO;
1017 					/* Cause @ctx to be sanitized below. */
1018 					ni = NULL;
1019 					break;
1020 				}
1021 				ctx->ntfs_ino = ni;
1022 			}
1023 			ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1024 					le16_to_cpu(ctx->mrec->attrs_offset));
1025 		}
1026 		/*
1027 		 * ctx->vfs_ino, ctx->mrec, and ctx->attr now point to the
1028 		 * mft record containing the attribute represented by the
1029 		 * current al_entry.
1030 		 */
1031 		/*
1032 		 * We could call into ntfs_attr_find() to find the right
1033 		 * attribute in this mft record but this would be less
1034 		 * efficient and not quite accurate as ntfs_attr_find() ignores
1035 		 * the attribute instance numbers for example which become
1036 		 * important when one plays with attribute lists.  Also,
1037 		 * because a proper match has been found in the attribute list
1038 		 * entry above, the comparison can now be optimized.  So it is
1039 		 * worth re-implementing a simplified ntfs_attr_find() here.
1040 		 */
1041 		a = ctx->attr;
1042 		/*
1043 		 * Use a manual loop so we can still use break and continue
1044 		 * with the same meanings as above.
1045 		 */
1046 do_next_attr_loop:
1047 		if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
1048 				le32_to_cpu(ctx->mrec->bytes_allocated))
1049 			break;
1050 		if (a->type == AT_END)
1051 			continue;
1052 		if (!a->length)
1053 			break;
1054 		if (al_entry->instance != a->instance)
1055 			goto do_next_attr;
1056 		/*
1057 		 * If the type and/or the name are mismatched between the
1058 		 * attribute list entry and the attribute record, there is
1059 		 * corruption so we break and return error EIO.
1060 		 */
1061 		if (al_entry->type != a->type)
1062 			break;
1063 		if (!ntfs_are_names_equal((ntfschar*)((u8*)a +
1064 				le16_to_cpu(a->name_offset)), a->name_length,
1065 				al_name, al_name_len, CASE_SENSITIVE,
1066 				vol->upcase, vol->upcase_len))
1067 			break;
1068 		ctx->attr = a;
1069 		/*
1070 		 * If no @val specified or @val specified and it matches, we
1071 		 * have found it!
1072 		 */
1073 		if (!val || (!a->non_resident && le32_to_cpu(
1074 				a->data.resident.value_length) == val_len &&
1075 				!memcmp((u8*)a +
1076 				le16_to_cpu(a->data.resident.value_offset),
1077 				val, val_len))) {
1078 			ntfs_debug("Done, found.");
1079 			return 0;
1080 		}
1081 do_next_attr:
1082 		/* Proceed to the next attribute in the current mft record. */
1083 		a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length));
1084 		goto do_next_attr_loop;
1085 	}
1086 	if (!err) {
1087 		ntfs_error(vol->sb, "Base inode 0x%lx contains corrupt "
1088 				"attribute list attribute.%s", base_ni->mft_no,
1089 				es);
1090 		err = -EIO;
1091 	}
1092 	if (ni != base_ni) {
1093 		if (ni)
1094 			unmap_extent_mft_record(ni);
1095 		ctx->ntfs_ino = base_ni;
1096 		ctx->mrec = ctx->base_mrec;
1097 		ctx->attr = ctx->base_attr;
1098 	}
1099 	if (err != -ENOMEM)
1100 		NVolSetErrors(vol);
1101 	return err;
1102 not_found:
1103 	/*
1104 	 * If we were looking for AT_END, we reset the search context @ctx and
1105 	 * use ntfs_attr_find() to seek to the end of the base mft record.
1106 	 */
1107 	if (type == AT_END) {
1108 		ntfs_attr_reinit_search_ctx(ctx);
1109 		return ntfs_attr_find(AT_END, name, name_len, ic, val, val_len,
1110 				ctx);
1111 	}
1112 	/*
1113 	 * The attribute was not found.  Before we return, we want to ensure
1114 	 * @ctx->mrec and @ctx->attr indicate the position at which the
1115 	 * attribute should be inserted in the base mft record.  Since we also
1116 	 * want to preserve @ctx->al_entry we cannot reinitialize the search
1117 	 * context using ntfs_attr_reinit_search_ctx() as this would set
1118 	 * @ctx->al_entry to NULL.  Thus we do the necessary bits manually (see
1119 	 * ntfs_attr_init_search_ctx() below).  Note, we _only_ preserve
1120 	 * @ctx->al_entry as the remaining fields (base_*) are identical to
1121 	 * their non base_ counterparts and we cannot set @ctx->base_attr
1122 	 * correctly yet as we do not know what @ctx->attr will be set to by
1123 	 * the call to ntfs_attr_find() below.
1124 	 */
1125 	if (ni != base_ni)
1126 		unmap_extent_mft_record(ni);
1127 	ctx->mrec = ctx->base_mrec;
1128 	ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1129 			le16_to_cpu(ctx->mrec->attrs_offset));
1130 	ctx->is_first = TRUE;
1131 	ctx->ntfs_ino = base_ni;
1132 	ctx->base_ntfs_ino = NULL;
1133 	ctx->base_mrec = NULL;
1134 	ctx->base_attr = NULL;
1135 	/*
1136 	 * In case there are multiple matches in the base mft record, need to
1137 	 * keep enumerating until we get an attribute not found response (or
1138 	 * another error), otherwise we would keep returning the same attribute
1139 	 * over and over again and all programs using us for enumeration would
1140 	 * lock up in a tight loop.
1141 	 */
1142 	do {
1143 		err = ntfs_attr_find(type, name, name_len, ic, val, val_len,
1144 				ctx);
1145 	} while (!err);
1146 	ntfs_debug("Done, not found.");
1147 	return err;
1148 }
1149 
1150 /**
1151  * ntfs_attr_lookup - find an attribute in an ntfs inode
1152  * @type:	attribute type to find
1153  * @name:	attribute name to find (optional, i.e. NULL means don't care)
1154  * @name_len:	attribute name length (only needed if @name present)
1155  * @ic:		IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
1156  * @lowest_vcn:	lowest vcn to find (optional, non-resident attributes only)
1157  * @val:	attribute value to find (optional, resident attributes only)
1158  * @val_len:	attribute value length
1159  * @ctx:	search context with mft record and attribute to search from
1160  *
1161  * Find an attribute in an ntfs inode.  On first search @ctx->ntfs_ino must
1162  * be the base mft record and @ctx must have been obtained from a call to
1163  * ntfs_attr_get_search_ctx().
1164  *
1165  * This function transparently handles attribute lists and @ctx is used to
1166  * continue searches where they were left off at.
1167  *
1168  * After finishing with the attribute/mft record you need to call
1169  * ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
1170  * mapped inodes, etc).
1171  *
1172  * Return 0 if the search was successful and -errno if not.
1173  *
1174  * When 0, @ctx->attr is the found attribute and it is in mft record
1175  * @ctx->mrec.  If an attribute list attribute is present, @ctx->al_entry is
1176  * the attribute list entry of the found attribute.
1177  *
1178  * When -ENOENT, @ctx->attr is the attribute which collates just after the
1179  * attribute being searched for, i.e. if one wants to add the attribute to the
1180  * mft record this is the correct place to insert it into.  If an attribute
1181  * list attribute is present, @ctx->al_entry is the attribute list entry which
1182  * collates just after the attribute list entry of the attribute being searched
1183  * for, i.e. if one wants to add the attribute to the mft record this is the
1184  * correct place to insert its attribute list entry into.
1185  *
1186  * When -errno != -ENOENT, an error occured during the lookup.  @ctx->attr is
1187  * then undefined and in particular you should not rely on it not changing.
1188  */
1189 int ntfs_attr_lookup(const ATTR_TYPE type, const ntfschar *name,
1190 		const u32 name_len, const IGNORE_CASE_BOOL ic,
1191 		const VCN lowest_vcn, const u8 *val, const u32 val_len,
1192 		ntfs_attr_search_ctx *ctx)
1193 {
1194 	ntfs_inode *base_ni;
1195 
1196 	ntfs_debug("Entering.");
1197 	BUG_ON(IS_ERR(ctx->mrec));
1198 	if (ctx->base_ntfs_ino)
1199 		base_ni = ctx->base_ntfs_ino;
1200 	else
1201 		base_ni = ctx->ntfs_ino;
1202 	/* Sanity check, just for debugging really. */
1203 	BUG_ON(!base_ni);
1204 	if (!NInoAttrList(base_ni) || type == AT_ATTRIBUTE_LIST)
1205 		return ntfs_attr_find(type, name, name_len, ic, val, val_len,
1206 				ctx);
1207 	return ntfs_external_attr_find(type, name, name_len, ic, lowest_vcn,
1208 			val, val_len, ctx);
1209 }
1210 
1211 /**
1212  * ntfs_attr_init_search_ctx - initialize an attribute search context
1213  * @ctx:	attribute search context to initialize
1214  * @ni:		ntfs inode with which to initialize the search context
1215  * @mrec:	mft record with which to initialize the search context
1216  *
1217  * Initialize the attribute search context @ctx with @ni and @mrec.
1218  */
1219 static inline void ntfs_attr_init_search_ctx(ntfs_attr_search_ctx *ctx,
1220 		ntfs_inode *ni, MFT_RECORD *mrec)
1221 {
1222 	*ctx = (ntfs_attr_search_ctx) {
1223 		.mrec = mrec,
1224 		/* Sanity checks are performed elsewhere. */
1225 		.attr = (ATTR_RECORD*)((u8*)mrec +
1226 				le16_to_cpu(mrec->attrs_offset)),
1227 		.is_first = TRUE,
1228 		.ntfs_ino = ni,
1229 	};
1230 }
1231 
1232 /**
1233  * ntfs_attr_reinit_search_ctx - reinitialize an attribute search context
1234  * @ctx:	attribute search context to reinitialize
1235  *
1236  * Reinitialize the attribute search context @ctx, unmapping an associated
1237  * extent mft record if present, and initialize the search context again.
1238  *
1239  * This is used when a search for a new attribute is being started to reset
1240  * the search context to the beginning.
1241  */
1242 void ntfs_attr_reinit_search_ctx(ntfs_attr_search_ctx *ctx)
1243 {
1244 	if (likely(!ctx->base_ntfs_ino)) {
1245 		/* No attribute list. */
1246 		ctx->is_first = TRUE;
1247 		/* Sanity checks are performed elsewhere. */
1248 		ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1249 				le16_to_cpu(ctx->mrec->attrs_offset));
1250 		/*
1251 		 * This needs resetting due to ntfs_external_attr_find() which
1252 		 * can leave it set despite having zeroed ctx->base_ntfs_ino.
1253 		 */
1254 		ctx->al_entry = NULL;
1255 		return;
1256 	} /* Attribute list. */
1257 	if (ctx->ntfs_ino != ctx->base_ntfs_ino)
1258 		unmap_extent_mft_record(ctx->ntfs_ino);
1259 	ntfs_attr_init_search_ctx(ctx, ctx->base_ntfs_ino, ctx->base_mrec);
1260 	return;
1261 }
1262 
1263 /**
1264  * ntfs_attr_get_search_ctx - allocate/initialize a new attribute search context
1265  * @ni:		ntfs inode with which to initialize the search context
1266  * @mrec:	mft record with which to initialize the search context
1267  *
1268  * Allocate a new attribute search context, initialize it with @ni and @mrec,
1269  * and return it. Return NULL if allocation failed.
1270  */
1271 ntfs_attr_search_ctx *ntfs_attr_get_search_ctx(ntfs_inode *ni, MFT_RECORD *mrec)
1272 {
1273 	ntfs_attr_search_ctx *ctx;
1274 
1275 	ctx = kmem_cache_alloc(ntfs_attr_ctx_cache, SLAB_NOFS);
1276 	if (ctx)
1277 		ntfs_attr_init_search_ctx(ctx, ni, mrec);
1278 	return ctx;
1279 }
1280 
1281 /**
1282  * ntfs_attr_put_search_ctx - release an attribute search context
1283  * @ctx:	attribute search context to free
1284  *
1285  * Release the attribute search context @ctx, unmapping an associated extent
1286  * mft record if present.
1287  */
1288 void ntfs_attr_put_search_ctx(ntfs_attr_search_ctx *ctx)
1289 {
1290 	if (ctx->base_ntfs_ino && ctx->ntfs_ino != ctx->base_ntfs_ino)
1291 		unmap_extent_mft_record(ctx->ntfs_ino);
1292 	kmem_cache_free(ntfs_attr_ctx_cache, ctx);
1293 	return;
1294 }
1295 
1296 #ifdef NTFS_RW
1297 
1298 /**
1299  * ntfs_attr_find_in_attrdef - find an attribute in the $AttrDef system file
1300  * @vol:	ntfs volume to which the attribute belongs
1301  * @type:	attribute type which to find
1302  *
1303  * Search for the attribute definition record corresponding to the attribute
1304  * @type in the $AttrDef system file.
1305  *
1306  * Return the attribute type definition record if found and NULL if not found.
1307  */
1308 static ATTR_DEF *ntfs_attr_find_in_attrdef(const ntfs_volume *vol,
1309 		const ATTR_TYPE type)
1310 {
1311 	ATTR_DEF *ad;
1312 
1313 	BUG_ON(!vol->attrdef);
1314 	BUG_ON(!type);
1315 	for (ad = vol->attrdef; (u8*)ad - (u8*)vol->attrdef <
1316 			vol->attrdef_size && ad->type; ++ad) {
1317 		/* We have not found it yet, carry on searching. */
1318 		if (likely(le32_to_cpu(ad->type) < le32_to_cpu(type)))
1319 			continue;
1320 		/* We found the attribute; return it. */
1321 		if (likely(ad->type == type))
1322 			return ad;
1323 		/* We have gone too far already.  No point in continuing. */
1324 		break;
1325 	}
1326 	/* Attribute not found. */
1327 	ntfs_debug("Attribute type 0x%x not found in $AttrDef.",
1328 			le32_to_cpu(type));
1329 	return NULL;
1330 }
1331 
1332 /**
1333  * ntfs_attr_size_bounds_check - check a size of an attribute type for validity
1334  * @vol:	ntfs volume to which the attribute belongs
1335  * @type:	attribute type which to check
1336  * @size:	size which to check
1337  *
1338  * Check whether the @size in bytes is valid for an attribute of @type on the
1339  * ntfs volume @vol.  This information is obtained from $AttrDef system file.
1340  *
1341  * Return 0 if valid, -ERANGE if not valid, or -ENOENT if the attribute is not
1342  * listed in $AttrDef.
1343  */
1344 int ntfs_attr_size_bounds_check(const ntfs_volume *vol, const ATTR_TYPE type,
1345 		const s64 size)
1346 {
1347 	ATTR_DEF *ad;
1348 
1349 	BUG_ON(size < 0);
1350 	/*
1351 	 * $ATTRIBUTE_LIST has a maximum size of 256kiB, but this is not
1352 	 * listed in $AttrDef.
1353 	 */
1354 	if (unlikely(type == AT_ATTRIBUTE_LIST && size > 256 * 1024))
1355 		return -ERANGE;
1356 	/* Get the $AttrDef entry for the attribute @type. */
1357 	ad = ntfs_attr_find_in_attrdef(vol, type);
1358 	if (unlikely(!ad))
1359 		return -ENOENT;
1360 	/* Do the bounds check. */
1361 	if (((sle64_to_cpu(ad->min_size) > 0) &&
1362 			size < sle64_to_cpu(ad->min_size)) ||
1363 			((sle64_to_cpu(ad->max_size) > 0) && size >
1364 			sle64_to_cpu(ad->max_size)))
1365 		return -ERANGE;
1366 	return 0;
1367 }
1368 
1369 /**
1370  * ntfs_attr_can_be_non_resident - check if an attribute can be non-resident
1371  * @vol:	ntfs volume to which the attribute belongs
1372  * @type:	attribute type which to check
1373  *
1374  * Check whether the attribute of @type on the ntfs volume @vol is allowed to
1375  * be non-resident.  This information is obtained from $AttrDef system file.
1376  *
1377  * Return 0 if the attribute is allowed to be non-resident, -EPERM if not, and
1378  * -ENOENT if the attribute is not listed in $AttrDef.
1379  */
1380 int ntfs_attr_can_be_non_resident(const ntfs_volume *vol, const ATTR_TYPE type)
1381 {
1382 	ATTR_DEF *ad;
1383 
1384 	/* Find the attribute definition record in $AttrDef. */
1385 	ad = ntfs_attr_find_in_attrdef(vol, type);
1386 	if (unlikely(!ad))
1387 		return -ENOENT;
1388 	/* Check the flags and return the result. */
1389 	if (ad->flags & ATTR_DEF_RESIDENT)
1390 		return -EPERM;
1391 	return 0;
1392 }
1393 
1394 /**
1395  * ntfs_attr_can_be_resident - check if an attribute can be resident
1396  * @vol:	ntfs volume to which the attribute belongs
1397  * @type:	attribute type which to check
1398  *
1399  * Check whether the attribute of @type on the ntfs volume @vol is allowed to
1400  * be resident.  This information is derived from our ntfs knowledge and may
1401  * not be completely accurate, especially when user defined attributes are
1402  * present.  Basically we allow everything to be resident except for index
1403  * allocation and $EA attributes.
1404  *
1405  * Return 0 if the attribute is allowed to be non-resident and -EPERM if not.
1406  *
1407  * Warning: In the system file $MFT the attribute $Bitmap must be non-resident
1408  *	    otherwise windows will not boot (blue screen of death)!  We cannot
1409  *	    check for this here as we do not know which inode's $Bitmap is
1410  *	    being asked about so the caller needs to special case this.
1411  */
1412 int ntfs_attr_can_be_resident(const ntfs_volume *vol, const ATTR_TYPE type)
1413 {
1414 	if (type == AT_INDEX_ALLOCATION)
1415 		return -EPERM;
1416 	return 0;
1417 }
1418 
1419 /**
1420  * ntfs_attr_record_resize - resize an attribute record
1421  * @m:		mft record containing attribute record
1422  * @a:		attribute record to resize
1423  * @new_size:	new size in bytes to which to resize the attribute record @a
1424  *
1425  * Resize the attribute record @a, i.e. the resident part of the attribute, in
1426  * the mft record @m to @new_size bytes.
1427  *
1428  * Return 0 on success and -errno on error.  The following error codes are
1429  * defined:
1430  *	-ENOSPC	- Not enough space in the mft record @m to perform the resize.
1431  *
1432  * Note: On error, no modifications have been performed whatsoever.
1433  *
1434  * Warning: If you make a record smaller without having copied all the data you
1435  *	    are interested in the data may be overwritten.
1436  */
1437 int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size)
1438 {
1439 	ntfs_debug("Entering for new_size %u.", new_size);
1440 	/* Align to 8 bytes if it is not already done. */
1441 	if (new_size & 7)
1442 		new_size = (new_size + 7) & ~7;
1443 	/* If the actual attribute length has changed, move things around. */
1444 	if (new_size != le32_to_cpu(a->length)) {
1445 		u32 new_muse = le32_to_cpu(m->bytes_in_use) -
1446 				le32_to_cpu(a->length) + new_size;
1447 		/* Not enough space in this mft record. */
1448 		if (new_muse > le32_to_cpu(m->bytes_allocated))
1449 			return -ENOSPC;
1450 		/* Move attributes following @a to their new location. */
1451 		memmove((u8*)a + new_size, (u8*)a + le32_to_cpu(a->length),
1452 				le32_to_cpu(m->bytes_in_use) - ((u8*)a -
1453 				(u8*)m) - le32_to_cpu(a->length));
1454 		/* Adjust @m to reflect the change in used space. */
1455 		m->bytes_in_use = cpu_to_le32(new_muse);
1456 		/* Adjust @a to reflect the new size. */
1457 		if (new_size >= offsetof(ATTR_REC, length) + sizeof(a->length))
1458 			a->length = cpu_to_le32(new_size);
1459 	}
1460 	return 0;
1461 }
1462 
1463 /**
1464  * ntfs_resident_attr_value_resize - resize the value of a resident attribute
1465  * @m:		mft record containing attribute record
1466  * @a:		attribute record whose value to resize
1467  * @new_size:	new size in bytes to which to resize the attribute value of @a
1468  *
1469  * Resize the value of the attribute @a in the mft record @m to @new_size bytes.
1470  * If the value is made bigger, the newly allocated space is cleared.
1471  *
1472  * Return 0 on success and -errno on error.  The following error codes are
1473  * defined:
1474  *	-ENOSPC	- Not enough space in the mft record @m to perform the resize.
1475  *
1476  * Note: On error, no modifications have been performed whatsoever.
1477  *
1478  * Warning: If you make a record smaller without having copied all the data you
1479  *	    are interested in the data may be overwritten.
1480  */
1481 int ntfs_resident_attr_value_resize(MFT_RECORD *m, ATTR_RECORD *a,
1482 		const u32 new_size)
1483 {
1484 	u32 old_size;
1485 
1486 	/* Resize the resident part of the attribute record. */
1487 	if (ntfs_attr_record_resize(m, a,
1488 			le16_to_cpu(a->data.resident.value_offset) + new_size))
1489 		return -ENOSPC;
1490 	/*
1491 	 * The resize succeeded!  If we made the attribute value bigger, clear
1492 	 * the area between the old size and @new_size.
1493 	 */
1494 	old_size = le32_to_cpu(a->data.resident.value_length);
1495 	if (new_size > old_size)
1496 		memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
1497 				old_size, 0, new_size - old_size);
1498 	/* Finally update the length of the attribute value. */
1499 	a->data.resident.value_length = cpu_to_le32(new_size);
1500 	return 0;
1501 }
1502 
1503 /**
1504  * ntfs_attr_make_non_resident - convert a resident to a non-resident attribute
1505  * @ni:		ntfs inode describing the attribute to convert
1506  * @data_size:	size of the resident data to copy to the non-resident attribute
1507  *
1508  * Convert the resident ntfs attribute described by the ntfs inode @ni to a
1509  * non-resident one.
1510  *
1511  * @data_size must be equal to the attribute value size.  This is needed since
1512  * we need to know the size before we can map the mft record and our callers
1513  * always know it.  The reason we cannot simply read the size from the vfs
1514  * inode i_size is that this is not necessarily uptodate.  This happens when
1515  * ntfs_attr_make_non_resident() is called in the ->truncate call path(s).
1516  *
1517  * Return 0 on success and -errno on error.  The following error return codes
1518  * are defined:
1519  *	-EPERM	- The attribute is not allowed to be non-resident.
1520  *	-ENOMEM	- Not enough memory.
1521  *	-ENOSPC	- Not enough disk space.
1522  *	-EINVAL	- Attribute not defined on the volume.
1523  *	-EIO	- I/o error or other error.
1524  * Note that -ENOSPC is also returned in the case that there is not enough
1525  * space in the mft record to do the conversion.  This can happen when the mft
1526  * record is already very full.  The caller is responsible for trying to make
1527  * space in the mft record and trying again.  FIXME: Do we need a separate
1528  * error return code for this kind of -ENOSPC or is it always worth trying
1529  * again in case the attribute may then fit in a resident state so no need to
1530  * make it non-resident at all?  Ho-hum...  (AIA)
1531  *
1532  * NOTE to self: No changes in the attribute list are required to move from
1533  *		 a resident to a non-resident attribute.
1534  *
1535  * Locking: - The caller must hold i_sem on the inode.
1536  */
1537 int ntfs_attr_make_non_resident(ntfs_inode *ni, const u32 data_size)
1538 {
1539 	s64 new_size;
1540 	struct inode *vi = VFS_I(ni);
1541 	ntfs_volume *vol = ni->vol;
1542 	ntfs_inode *base_ni;
1543 	MFT_RECORD *m;
1544 	ATTR_RECORD *a;
1545 	ntfs_attr_search_ctx *ctx;
1546 	struct page *page;
1547 	runlist_element *rl;
1548 	u8 *kaddr;
1549 	unsigned long flags;
1550 	int mp_size, mp_ofs, name_ofs, arec_size, err, err2;
1551 	u32 attr_size;
1552 	u8 old_res_attr_flags;
1553 
1554 	/* Check that the attribute is allowed to be non-resident. */
1555 	err = ntfs_attr_can_be_non_resident(vol, ni->type);
1556 	if (unlikely(err)) {
1557 		if (err == -EPERM)
1558 			ntfs_debug("Attribute is not allowed to be "
1559 					"non-resident.");
1560 		else
1561 			ntfs_debug("Attribute not defined on the NTFS "
1562 					"volume!");
1563 		return err;
1564 	}
1565 	/*
1566 	 * FIXME: Compressed and encrypted attributes are not supported when
1567 	 * writing and we should never have gotten here for them.
1568 	 */
1569 	BUG_ON(NInoCompressed(ni));
1570 	BUG_ON(NInoEncrypted(ni));
1571 	/*
1572 	 * The size needs to be aligned to a cluster boundary for allocation
1573 	 * purposes.
1574 	 */
1575 	new_size = (data_size + vol->cluster_size - 1) &
1576 			~(vol->cluster_size - 1);
1577 	if (new_size > 0) {
1578 		/*
1579 		 * Will need the page later and since the page lock nests
1580 		 * outside all ntfs locks, we need to get the page now.
1581 		 */
1582 		page = find_or_create_page(vi->i_mapping, 0,
1583 				mapping_gfp_mask(vi->i_mapping));
1584 		if (unlikely(!page))
1585 			return -ENOMEM;
1586 		/* Start by allocating clusters to hold the attribute value. */
1587 		rl = ntfs_cluster_alloc(vol, 0, new_size >>
1588 				vol->cluster_size_bits, -1, DATA_ZONE, TRUE);
1589 		if (IS_ERR(rl)) {
1590 			err = PTR_ERR(rl);
1591 			ntfs_debug("Failed to allocate cluster%s, error code "
1592 					"%i.", (new_size >>
1593 					vol->cluster_size_bits) > 1 ? "s" : "",
1594 					err);
1595 			goto page_err_out;
1596 		}
1597 	} else {
1598 		rl = NULL;
1599 		page = NULL;
1600 	}
1601 	/* Determine the size of the mapping pairs array. */
1602 	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl, 0, -1);
1603 	if (unlikely(mp_size < 0)) {
1604 		err = mp_size;
1605 		ntfs_debug("Failed to get size for mapping pairs array, error "
1606 				"code %i.", err);
1607 		goto rl_err_out;
1608 	}
1609 	down_write(&ni->runlist.lock);
1610 	if (!NInoAttr(ni))
1611 		base_ni = ni;
1612 	else
1613 		base_ni = ni->ext.base_ntfs_ino;
1614 	m = map_mft_record(base_ni);
1615 	if (IS_ERR(m)) {
1616 		err = PTR_ERR(m);
1617 		m = NULL;
1618 		ctx = NULL;
1619 		goto err_out;
1620 	}
1621 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1622 	if (unlikely(!ctx)) {
1623 		err = -ENOMEM;
1624 		goto err_out;
1625 	}
1626 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1627 			CASE_SENSITIVE, 0, NULL, 0, ctx);
1628 	if (unlikely(err)) {
1629 		if (err == -ENOENT)
1630 			err = -EIO;
1631 		goto err_out;
1632 	}
1633 	m = ctx->mrec;
1634 	a = ctx->attr;
1635 	BUG_ON(NInoNonResident(ni));
1636 	BUG_ON(a->non_resident);
1637 	/*
1638 	 * Calculate new offsets for the name and the mapping pairs array.
1639 	 */
1640 	if (NInoSparse(ni) || NInoCompressed(ni))
1641 		name_ofs = (offsetof(ATTR_REC,
1642 				data.non_resident.compressed_size) +
1643 				sizeof(a->data.non_resident.compressed_size) +
1644 				7) & ~7;
1645 	else
1646 		name_ofs = (offsetof(ATTR_REC,
1647 				data.non_resident.compressed_size) + 7) & ~7;
1648 	mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
1649 	/*
1650 	 * Determine the size of the resident part of the now non-resident
1651 	 * attribute record.
1652 	 */
1653 	arec_size = (mp_ofs + mp_size + 7) & ~7;
1654 	/*
1655 	 * If the page is not uptodate bring it uptodate by copying from the
1656 	 * attribute value.
1657 	 */
1658 	attr_size = le32_to_cpu(a->data.resident.value_length);
1659 	BUG_ON(attr_size != data_size);
1660 	if (page && !PageUptodate(page)) {
1661 		kaddr = kmap_atomic(page, KM_USER0);
1662 		memcpy(kaddr, (u8*)a +
1663 				le16_to_cpu(a->data.resident.value_offset),
1664 				attr_size);
1665 		memset(kaddr + attr_size, 0, PAGE_CACHE_SIZE - attr_size);
1666 		kunmap_atomic(kaddr, KM_USER0);
1667 		flush_dcache_page(page);
1668 		SetPageUptodate(page);
1669 	}
1670 	/* Backup the attribute flag. */
1671 	old_res_attr_flags = a->data.resident.flags;
1672 	/* Resize the resident part of the attribute record. */
1673 	err = ntfs_attr_record_resize(m, a, arec_size);
1674 	if (unlikely(err))
1675 		goto err_out;
1676 	/*
1677 	 * Convert the resident part of the attribute record to describe a
1678 	 * non-resident attribute.
1679 	 */
1680 	a->non_resident = 1;
1681 	/* Move the attribute name if it exists and update the offset. */
1682 	if (a->name_length)
1683 		memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
1684 				a->name_length * sizeof(ntfschar));
1685 	a->name_offset = cpu_to_le16(name_ofs);
1686 	/* Setup the fields specific to non-resident attributes. */
1687 	a->data.non_resident.lowest_vcn = 0;
1688 	a->data.non_resident.highest_vcn = cpu_to_sle64((new_size - 1) >>
1689 			vol->cluster_size_bits);
1690 	a->data.non_resident.mapping_pairs_offset = cpu_to_le16(mp_ofs);
1691 	memset(&a->data.non_resident.reserved, 0,
1692 			sizeof(a->data.non_resident.reserved));
1693 	a->data.non_resident.allocated_size = cpu_to_sle64(new_size);
1694 	a->data.non_resident.data_size =
1695 			a->data.non_resident.initialized_size =
1696 			cpu_to_sle64(attr_size);
1697 	if (NInoSparse(ni) || NInoCompressed(ni)) {
1698 		a->data.non_resident.compression_unit = 4;
1699 		a->data.non_resident.compressed_size =
1700 				a->data.non_resident.allocated_size;
1701 	} else
1702 		a->data.non_resident.compression_unit = 0;
1703 	/* Generate the mapping pairs array into the attribute record. */
1704 	err = ntfs_mapping_pairs_build(vol, (u8*)a + mp_ofs,
1705 			arec_size - mp_ofs, rl, 0, -1, NULL);
1706 	if (unlikely(err)) {
1707 		ntfs_debug("Failed to build mapping pairs, error code %i.",
1708 				err);
1709 		goto undo_err_out;
1710 	}
1711 	/* Setup the in-memory attribute structure to be non-resident. */
1712 	ni->runlist.rl = rl;
1713 	write_lock_irqsave(&ni->size_lock, flags);
1714 	ni->allocated_size = new_size;
1715 	if (NInoSparse(ni) || NInoCompressed(ni)) {
1716 		ni->itype.compressed.size = ni->allocated_size;
1717 		ni->itype.compressed.block_size = 1U <<
1718 				(a->data.non_resident.compression_unit +
1719 				vol->cluster_size_bits);
1720 		ni->itype.compressed.block_size_bits =
1721 				ffs(ni->itype.compressed.block_size) - 1;
1722 		ni->itype.compressed.block_clusters = 1U <<
1723 				a->data.non_resident.compression_unit;
1724 		vi->i_blocks = ni->itype.compressed.size >> 9;
1725 	} else
1726 		vi->i_blocks = ni->allocated_size >> 9;
1727 	write_unlock_irqrestore(&ni->size_lock, flags);
1728 	/*
1729 	 * This needs to be last since the address space operations ->readpage
1730 	 * and ->writepage can run concurrently with us as they are not
1731 	 * serialized on i_sem.  Note, we are not allowed to fail once we flip
1732 	 * this switch, which is another reason to do this last.
1733 	 */
1734 	NInoSetNonResident(ni);
1735 	/* Mark the mft record dirty, so it gets written back. */
1736 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1737 	mark_mft_record_dirty(ctx->ntfs_ino);
1738 	ntfs_attr_put_search_ctx(ctx);
1739 	unmap_mft_record(base_ni);
1740 	up_write(&ni->runlist.lock);
1741 	if (page) {
1742 		set_page_dirty(page);
1743 		unlock_page(page);
1744 		mark_page_accessed(page);
1745 		page_cache_release(page);
1746 	}
1747 	ntfs_debug("Done.");
1748 	return 0;
1749 undo_err_out:
1750 	/* Convert the attribute back into a resident attribute. */
1751 	a->non_resident = 0;
1752 	/* Move the attribute name if it exists and update the offset. */
1753 	name_ofs = (offsetof(ATTR_RECORD, data.resident.reserved) +
1754 			sizeof(a->data.resident.reserved) + 7) & ~7;
1755 	if (a->name_length)
1756 		memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
1757 				a->name_length * sizeof(ntfschar));
1758 	mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
1759 	a->name_offset = cpu_to_le16(name_ofs);
1760 	arec_size = (mp_ofs + attr_size + 7) & ~7;
1761 	/* Resize the resident part of the attribute record. */
1762 	err2 = ntfs_attr_record_resize(m, a, arec_size);
1763 	if (unlikely(err2)) {
1764 		/*
1765 		 * This cannot happen (well if memory corruption is at work it
1766 		 * could happen in theory), but deal with it as well as we can.
1767 		 * If the old size is too small, truncate the attribute,
1768 		 * otherwise simply give it a larger allocated size.
1769 		 * FIXME: Should check whether chkdsk complains when the
1770 		 * allocated size is much bigger than the resident value size.
1771 		 */
1772 		arec_size = le32_to_cpu(a->length);
1773 		if ((mp_ofs + attr_size) > arec_size) {
1774 			err2 = attr_size;
1775 			attr_size = arec_size - mp_ofs;
1776 			ntfs_error(vol->sb, "Failed to undo partial resident "
1777 					"to non-resident attribute "
1778 					"conversion.  Truncating inode 0x%lx, "
1779 					"attribute type 0x%x from %i bytes to "
1780 					"%i bytes to maintain metadata "
1781 					"consistency.  THIS MEANS YOU ARE "
1782 					"LOSING %i BYTES DATA FROM THIS %s.",
1783 					vi->i_ino,
1784 					(unsigned)le32_to_cpu(ni->type),
1785 					err2, attr_size, err2 - attr_size,
1786 					((ni->type == AT_DATA) &&
1787 					!ni->name_len) ? "FILE": "ATTRIBUTE");
1788 			write_lock_irqsave(&ni->size_lock, flags);
1789 			ni->initialized_size = attr_size;
1790 			i_size_write(vi, attr_size);
1791 			write_unlock_irqrestore(&ni->size_lock, flags);
1792 		}
1793 	}
1794 	/* Setup the fields specific to resident attributes. */
1795 	a->data.resident.value_length = cpu_to_le32(attr_size);
1796 	a->data.resident.value_offset = cpu_to_le16(mp_ofs);
1797 	a->data.resident.flags = old_res_attr_flags;
1798 	memset(&a->data.resident.reserved, 0,
1799 			sizeof(a->data.resident.reserved));
1800 	/* Copy the data from the page back to the attribute value. */
1801 	if (page) {
1802 		kaddr = kmap_atomic(page, KM_USER0);
1803 		memcpy((u8*)a + mp_ofs, kaddr, attr_size);
1804 		kunmap_atomic(kaddr, KM_USER0);
1805 	}
1806 	/* Setup the allocated size in the ntfs inode in case it changed. */
1807 	write_lock_irqsave(&ni->size_lock, flags);
1808 	ni->allocated_size = arec_size - mp_ofs;
1809 	write_unlock_irqrestore(&ni->size_lock, flags);
1810 	/* Mark the mft record dirty, so it gets written back. */
1811 	flush_dcache_mft_record_page(ctx->ntfs_ino);
1812 	mark_mft_record_dirty(ctx->ntfs_ino);
1813 err_out:
1814 	if (ctx)
1815 		ntfs_attr_put_search_ctx(ctx);
1816 	if (m)
1817 		unmap_mft_record(base_ni);
1818 	ni->runlist.rl = NULL;
1819 	up_write(&ni->runlist.lock);
1820 rl_err_out:
1821 	if (rl) {
1822 		if (ntfs_cluster_free_from_rl(vol, rl) < 0) {
1823 			ntfs_error(vol->sb, "Failed to release allocated "
1824 					"cluster(s) in error code path.  Run "
1825 					"chkdsk to recover the lost "
1826 					"cluster(s).");
1827 			NVolSetErrors(vol);
1828 		}
1829 		ntfs_free(rl);
1830 page_err_out:
1831 		unlock_page(page);
1832 		page_cache_release(page);
1833 	}
1834 	if (err == -EINVAL)
1835 		err = -EIO;
1836 	return err;
1837 }
1838 
1839 /**
1840  * ntfs_attr_extend_allocation - extend the allocated space of an attribute
1841  * @ni:			ntfs inode of the attribute whose allocation to extend
1842  * @new_alloc_size:	new size in bytes to which to extend the allocation to
1843  * @new_data_size:	new size in bytes to which to extend the data to
1844  * @data_start:		beginning of region which is required to be non-sparse
1845  *
1846  * Extend the allocated space of an attribute described by the ntfs inode @ni
1847  * to @new_alloc_size bytes.  If @data_start is -1, the whole extension may be
1848  * implemented as a hole in the file (as long as both the volume and the ntfs
1849  * inode @ni have sparse support enabled).  If @data_start is >= 0, then the
1850  * region between the old allocated size and @data_start - 1 may be made sparse
1851  * but the regions between @data_start and @new_alloc_size must be backed by
1852  * actual clusters.
1853  *
1854  * If @new_data_size is -1, it is ignored.  If it is >= 0, then the data size
1855  * of the attribute is extended to @new_data_size.  Note that the i_size of the
1856  * vfs inode is not updated.  Only the data size in the base attribute record
1857  * is updated.  The caller has to update i_size separately if this is required.
1858  * WARNING: It is a BUG() for @new_data_size to be smaller than the old data
1859  * size as well as for @new_data_size to be greater than @new_alloc_size.
1860  *
1861  * For resident attributes this involves resizing the attribute record and if
1862  * necessary moving it and/or other attributes into extent mft records and/or
1863  * converting the attribute to a non-resident attribute which in turn involves
1864  * extending the allocation of a non-resident attribute as described below.
1865  *
1866  * For non-resident attributes this involves allocating clusters in the data
1867  * zone on the volume (except for regions that are being made sparse) and
1868  * extending the run list to describe the allocated clusters as well as
1869  * updating the mapping pairs array of the attribute.  This in turn involves
1870  * resizing the attribute record and if necessary moving it and/or other
1871  * attributes into extent mft records and/or splitting the attribute record
1872  * into multiple extent attribute records.
1873  *
1874  * Also, the attribute list attribute is updated if present and in some of the
1875  * above cases (the ones where extent mft records/attributes come into play),
1876  * an attribute list attribute is created if not already present.
1877  *
1878  * Return the new allocated size on success and -errno on error.  In the case
1879  * that an error is encountered but a partial extension at least up to
1880  * @data_start (if present) is possible, the allocation is partially extended
1881  * and this is returned.  This means the caller must check the returned size to
1882  * determine if the extension was partial.  If @data_start is -1 then partial
1883  * allocations are not performed.
1884  *
1885  * WARNING: Do not call ntfs_attr_extend_allocation() for $MFT/$DATA.
1886  *
1887  * Locking: This function takes the runlist lock of @ni for writing as well as
1888  * locking the mft record of the base ntfs inode.  These locks are maintained
1889  * throughout execution of the function.  These locks are required so that the
1890  * attribute can be resized safely and so that it can for example be converted
1891  * from resident to non-resident safely.
1892  *
1893  * TODO: At present attribute list attribute handling is not implemented.
1894  *
1895  * TODO: At present it is not safe to call this function for anything other
1896  * than the $DATA attribute(s) of an uncompressed and unencrypted file.
1897  */
1898 s64 ntfs_attr_extend_allocation(ntfs_inode *ni, s64 new_alloc_size,
1899 		const s64 new_data_size, const s64 data_start)
1900 {
1901 	VCN vcn;
1902 	s64 ll, allocated_size, start = data_start;
1903 	struct inode *vi = VFS_I(ni);
1904 	ntfs_volume *vol = ni->vol;
1905 	ntfs_inode *base_ni;
1906 	MFT_RECORD *m;
1907 	ATTR_RECORD *a;
1908 	ntfs_attr_search_ctx *ctx;
1909 	runlist_element *rl, *rl2;
1910 	unsigned long flags;
1911 	int err, mp_size;
1912 	u32 attr_len = 0; /* Silence stupid gcc warning. */
1913 	BOOL mp_rebuilt;
1914 
1915 #ifdef NTFS_DEBUG
1916 	read_lock_irqsave(&ni->size_lock, flags);
1917 	allocated_size = ni->allocated_size;
1918 	read_unlock_irqrestore(&ni->size_lock, flags);
1919 	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
1920 			"old_allocated_size 0x%llx, "
1921 			"new_allocated_size 0x%llx, new_data_size 0x%llx, "
1922 			"data_start 0x%llx.", vi->i_ino,
1923 			(unsigned)le32_to_cpu(ni->type),
1924 			(unsigned long long)allocated_size,
1925 			(unsigned long long)new_alloc_size,
1926 			(unsigned long long)new_data_size,
1927 			(unsigned long long)start);
1928 #endif
1929 retry_extend:
1930 	/*
1931 	 * For non-resident attributes, @start and @new_size need to be aligned
1932 	 * to cluster boundaries for allocation purposes.
1933 	 */
1934 	if (NInoNonResident(ni)) {
1935 		if (start > 0)
1936 			start &= ~(s64)vol->cluster_size_mask;
1937 		new_alloc_size = (new_alloc_size + vol->cluster_size - 1) &
1938 				~(s64)vol->cluster_size_mask;
1939 	}
1940 	BUG_ON(new_data_size >= 0 && new_data_size > new_alloc_size);
1941 	/* Check if new size is allowed in $AttrDef. */
1942 	err = ntfs_attr_size_bounds_check(vol, ni->type, new_alloc_size);
1943 	if (unlikely(err)) {
1944 		/* Only emit errors when the write will fail completely. */
1945 		read_lock_irqsave(&ni->size_lock, flags);
1946 		allocated_size = ni->allocated_size;
1947 		read_unlock_irqrestore(&ni->size_lock, flags);
1948 		if (start < 0 || start >= allocated_size) {
1949 			if (err == -ERANGE) {
1950 				ntfs_error(vol->sb, "Cannot extend allocation "
1951 						"of inode 0x%lx, attribute "
1952 						"type 0x%x, because the new "
1953 						"allocation would exceed the "
1954 						"maximum allowed size for "
1955 						"this attribute type.",
1956 						vi->i_ino, (unsigned)
1957 						le32_to_cpu(ni->type));
1958 			} else {
1959 				ntfs_error(vol->sb, "Cannot extend allocation "
1960 						"of inode 0x%lx, attribute "
1961 						"type 0x%x, because this "
1962 						"attribute type is not "
1963 						"defined on the NTFS volume.  "
1964 						"Possible corruption!  You "
1965 						"should run chkdsk!",
1966 						vi->i_ino, (unsigned)
1967 						le32_to_cpu(ni->type));
1968 			}
1969 		}
1970 		/* Translate error code to be POSIX conformant for write(2). */
1971 		if (err == -ERANGE)
1972 			err = -EFBIG;
1973 		else
1974 			err = -EIO;
1975 		return err;
1976 	}
1977 	if (!NInoAttr(ni))
1978 		base_ni = ni;
1979 	else
1980 		base_ni = ni->ext.base_ntfs_ino;
1981 	/*
1982 	 * We will be modifying both the runlist (if non-resident) and the mft
1983 	 * record so lock them both down.
1984 	 */
1985 	down_write(&ni->runlist.lock);
1986 	m = map_mft_record(base_ni);
1987 	if (IS_ERR(m)) {
1988 		err = PTR_ERR(m);
1989 		m = NULL;
1990 		ctx = NULL;
1991 		goto err_out;
1992 	}
1993 	ctx = ntfs_attr_get_search_ctx(base_ni, m);
1994 	if (unlikely(!ctx)) {
1995 		err = -ENOMEM;
1996 		goto err_out;
1997 	}
1998 	read_lock_irqsave(&ni->size_lock, flags);
1999 	allocated_size = ni->allocated_size;
2000 	read_unlock_irqrestore(&ni->size_lock, flags);
2001 	/*
2002 	 * If non-resident, seek to the last extent.  If resident, there is
2003 	 * only one extent, so seek to that.
2004 	 */
2005 	vcn = NInoNonResident(ni) ? allocated_size >> vol->cluster_size_bits :
2006 			0;
2007 	/*
2008 	 * Abort if someone did the work whilst we waited for the locks.  If we
2009 	 * just converted the attribute from resident to non-resident it is
2010 	 * likely that exactly this has happened already.  We cannot quite
2011 	 * abort if we need to update the data size.
2012 	 */
2013 	if (unlikely(new_alloc_size <= allocated_size)) {
2014 		ntfs_debug("Allocated size already exceeds requested size.");
2015 		new_alloc_size = allocated_size;
2016 		if (new_data_size < 0)
2017 			goto done;
2018 		/*
2019 		 * We want the first attribute extent so that we can update the
2020 		 * data size.
2021 		 */
2022 		vcn = 0;
2023 	}
2024 	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
2025 			CASE_SENSITIVE, vcn, NULL, 0, ctx);
2026 	if (unlikely(err)) {
2027 		if (err == -ENOENT)
2028 			err = -EIO;
2029 		goto err_out;
2030 	}
2031 	m = ctx->mrec;
2032 	a = ctx->attr;
2033 	/* Use goto to reduce indentation. */
2034 	if (a->non_resident)
2035 		goto do_non_resident_extend;
2036 	BUG_ON(NInoNonResident(ni));
2037 	/* The total length of the attribute value. */
2038 	attr_len = le32_to_cpu(a->data.resident.value_length);
2039 	/*
2040 	 * Extend the attribute record to be able to store the new attribute
2041 	 * size.  ntfs_attr_record_resize() will not do anything if the size is
2042 	 * not changing.
2043 	 */
2044 	if (new_alloc_size < vol->mft_record_size &&
2045 			!ntfs_attr_record_resize(m, a,
2046 			le16_to_cpu(a->data.resident.value_offset) +
2047 			new_alloc_size)) {
2048 		/* The resize succeeded! */
2049 		write_lock_irqsave(&ni->size_lock, flags);
2050 		ni->allocated_size = le32_to_cpu(a->length) -
2051 				le16_to_cpu(a->data.resident.value_offset);
2052 		write_unlock_irqrestore(&ni->size_lock, flags);
2053 		if (new_data_size >= 0) {
2054 			BUG_ON(new_data_size < attr_len);
2055 			a->data.resident.value_length =
2056 					cpu_to_le32((u32)new_data_size);
2057 		}
2058 		goto flush_done;
2059 	}
2060 	/*
2061 	 * We have to drop all the locks so we can call
2062 	 * ntfs_attr_make_non_resident().  This could be optimised by try-
2063 	 * locking the first page cache page and only if that fails dropping
2064 	 * the locks, locking the page, and redoing all the locking and
2065 	 * lookups.  While this would be a huge optimisation, it is not worth
2066 	 * it as this is definitely a slow code path.
2067 	 */
2068 	ntfs_attr_put_search_ctx(ctx);
2069 	unmap_mft_record(base_ni);
2070 	up_write(&ni->runlist.lock);
2071 	/*
2072 	 * Not enough space in the mft record, try to make the attribute
2073 	 * non-resident and if successful restart the extension process.
2074 	 */
2075 	err = ntfs_attr_make_non_resident(ni, attr_len);
2076 	if (likely(!err))
2077 		goto retry_extend;
2078 	/*
2079 	 * Could not make non-resident.  If this is due to this not being
2080 	 * permitted for this attribute type or there not being enough space,
2081 	 * try to make other attributes non-resident.  Otherwise fail.
2082 	 */
2083 	if (unlikely(err != -EPERM && err != -ENOSPC)) {
2084 		/* Only emit errors when the write will fail completely. */
2085 		read_lock_irqsave(&ni->size_lock, flags);
2086 		allocated_size = ni->allocated_size;
2087 		read_unlock_irqrestore(&ni->size_lock, flags);
2088 		if (start < 0 || start >= allocated_size)
2089 			ntfs_error(vol->sb, "Cannot extend allocation of "
2090 					"inode 0x%lx, attribute type 0x%x, "
2091 					"because the conversion from resident "
2092 					"to non-resident attribute failed "
2093 					"with error code %i.", vi->i_ino,
2094 					(unsigned)le32_to_cpu(ni->type), err);
2095 		if (err != -ENOMEM)
2096 			err = -EIO;
2097 		goto conv_err_out;
2098 	}
2099 	/* TODO: Not implemented from here, abort. */
2100 	read_lock_irqsave(&ni->size_lock, flags);
2101 	allocated_size = ni->allocated_size;
2102 	read_unlock_irqrestore(&ni->size_lock, flags);
2103 	if (start < 0 || start >= allocated_size) {
2104 		if (err == -ENOSPC)
2105 			ntfs_error(vol->sb, "Not enough space in the mft "
2106 					"record/on disk for the non-resident "
2107 					"attribute value.  This case is not "
2108 					"implemented yet.");
2109 		else /* if (err == -EPERM) */
2110 			ntfs_error(vol->sb, "This attribute type may not be "
2111 					"non-resident.  This case is not "
2112 					"implemented yet.");
2113 	}
2114 	err = -EOPNOTSUPP;
2115 	goto conv_err_out;
2116 #if 0
2117 	// TODO: Attempt to make other attributes non-resident.
2118 	if (!err)
2119 		goto do_resident_extend;
2120 	/*
2121 	 * Both the attribute list attribute and the standard information
2122 	 * attribute must remain in the base inode.  Thus, if this is one of
2123 	 * these attributes, we have to try to move other attributes out into
2124 	 * extent mft records instead.
2125 	 */
2126 	if (ni->type == AT_ATTRIBUTE_LIST ||
2127 			ni->type == AT_STANDARD_INFORMATION) {
2128 		// TODO: Attempt to move other attributes into extent mft
2129 		// records.
2130 		err = -EOPNOTSUPP;
2131 		if (!err)
2132 			goto do_resident_extend;
2133 		goto err_out;
2134 	}
2135 	// TODO: Attempt to move this attribute to an extent mft record, but
2136 	// only if it is not already the only attribute in an mft record in
2137 	// which case there would be nothing to gain.
2138 	err = -EOPNOTSUPP;
2139 	if (!err)
2140 		goto do_resident_extend;
2141 	/* There is nothing we can do to make enough space. )-: */
2142 	goto err_out;
2143 #endif
2144 do_non_resident_extend:
2145 	BUG_ON(!NInoNonResident(ni));
2146 	if (new_alloc_size == allocated_size) {
2147 		BUG_ON(vcn);
2148 		goto alloc_done;
2149 	}
2150 	/*
2151 	 * If the data starts after the end of the old allocation, this is a
2152 	 * $DATA attribute and sparse attributes are enabled on the volume and
2153 	 * for this inode, then create a sparse region between the old
2154 	 * allocated size and the start of the data.  Otherwise simply proceed
2155 	 * with filling the whole space between the old allocated size and the
2156 	 * new allocated size with clusters.
2157 	 */
2158 	if ((start >= 0 && start <= allocated_size) || ni->type != AT_DATA ||
2159 			!NVolSparseEnabled(vol) || NInoSparseDisabled(ni))
2160 		goto skip_sparse;
2161 	// TODO: This is not implemented yet.  We just fill in with real
2162 	// clusters for now...
2163 	ntfs_debug("Inserting holes is not-implemented yet.  Falling back to "
2164 			"allocating real clusters instead.");
2165 skip_sparse:
2166 	rl = ni->runlist.rl;
2167 	if (likely(rl)) {
2168 		/* Seek to the end of the runlist. */
2169 		while (rl->length)
2170 			rl++;
2171 	}
2172 	/* If this attribute extent is not mapped, map it now. */
2173 	if (unlikely(!rl || rl->lcn == LCN_RL_NOT_MAPPED ||
2174 			(rl->lcn == LCN_ENOENT && rl > ni->runlist.rl &&
2175 			(rl-1)->lcn == LCN_RL_NOT_MAPPED))) {
2176 		if (!rl && !allocated_size)
2177 			goto first_alloc;
2178 		rl = ntfs_mapping_pairs_decompress(vol, a, ni->runlist.rl);
2179 		if (IS_ERR(rl)) {
2180 			err = PTR_ERR(rl);
2181 			if (start < 0 || start >= allocated_size)
2182 				ntfs_error(vol->sb, "Cannot extend allocation "
2183 						"of inode 0x%lx, attribute "
2184 						"type 0x%x, because the "
2185 						"mapping of a runlist "
2186 						"fragment failed with error "
2187 						"code %i.", vi->i_ino,
2188 						(unsigned)le32_to_cpu(ni->type),
2189 						err);
2190 			if (err != -ENOMEM)
2191 				err = -EIO;
2192 			goto err_out;
2193 		}
2194 		ni->runlist.rl = rl;
2195 		/* Seek to the end of the runlist. */
2196 		while (rl->length)
2197 			rl++;
2198 	}
2199 	/*
2200 	 * We now know the runlist of the last extent is mapped and @rl is at
2201 	 * the end of the runlist.  We want to begin allocating clusters
2202 	 * starting at the last allocated cluster to reduce fragmentation.  If
2203 	 * there are no valid LCNs in the attribute we let the cluster
2204 	 * allocator choose the starting cluster.
2205 	 */
2206 	/* If the last LCN is a hole or simillar seek back to last real LCN. */
2207 	while (rl->lcn < 0 && rl > ni->runlist.rl)
2208 		rl--;
2209 first_alloc:
2210 	// FIXME: Need to implement partial allocations so at least part of the
2211 	// write can be performed when start >= 0.  (Needed for POSIX write(2)
2212 	// conformance.)
2213 	rl2 = ntfs_cluster_alloc(vol, allocated_size >> vol->cluster_size_bits,
2214 			(new_alloc_size - allocated_size) >>
2215 			vol->cluster_size_bits, (rl && (rl->lcn >= 0)) ?
2216 			rl->lcn + rl->length : -1, DATA_ZONE, TRUE);
2217 	if (IS_ERR(rl2)) {
2218 		err = PTR_ERR(rl2);
2219 		if (start < 0 || start >= allocated_size)
2220 			ntfs_error(vol->sb, "Cannot extend allocation of "
2221 					"inode 0x%lx, attribute type 0x%x, "
2222 					"because the allocation of clusters "
2223 					"failed with error code %i.", vi->i_ino,
2224 					(unsigned)le32_to_cpu(ni->type), err);
2225 		if (err != -ENOMEM && err != -ENOSPC)
2226 			err = -EIO;
2227 		goto err_out;
2228 	}
2229 	rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
2230 	if (IS_ERR(rl)) {
2231 		err = PTR_ERR(rl);
2232 		if (start < 0 || start >= allocated_size)
2233 			ntfs_error(vol->sb, "Cannot extend allocation of "
2234 					"inode 0x%lx, attribute type 0x%x, "
2235 					"because the runlist merge failed "
2236 					"with error code %i.", vi->i_ino,
2237 					(unsigned)le32_to_cpu(ni->type), err);
2238 		if (err != -ENOMEM)
2239 			err = -EIO;
2240 		if (ntfs_cluster_free_from_rl(vol, rl2)) {
2241 			ntfs_error(vol->sb, "Failed to release allocated "
2242 					"cluster(s) in error code path.  Run "
2243 					"chkdsk to recover the lost "
2244 					"cluster(s).");
2245 			NVolSetErrors(vol);
2246 		}
2247 		ntfs_free(rl2);
2248 		goto err_out;
2249 	}
2250 	ni->runlist.rl = rl;
2251 	ntfs_debug("Allocated 0x%llx clusters.", (long long)(new_alloc_size -
2252 			allocated_size) >> vol->cluster_size_bits);
2253 	/* Find the runlist element with which the attribute extent starts. */
2254 	ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
2255 	rl2 = ntfs_rl_find_vcn_nolock(rl, ll);
2256 	BUG_ON(!rl2);
2257 	BUG_ON(!rl2->length);
2258 	BUG_ON(rl2->lcn < LCN_HOLE);
2259 	mp_rebuilt = FALSE;
2260 	/* Get the size for the new mapping pairs array for this extent. */
2261 	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
2262 	if (unlikely(mp_size <= 0)) {
2263 		err = mp_size;
2264 		if (start < 0 || start >= allocated_size)
2265 			ntfs_error(vol->sb, "Cannot extend allocation of "
2266 					"inode 0x%lx, attribute type 0x%x, "
2267 					"because determining the size for the "
2268 					"mapping pairs failed with error code "
2269 					"%i.", vi->i_ino,
2270 					(unsigned)le32_to_cpu(ni->type), err);
2271 		err = -EIO;
2272 		goto undo_alloc;
2273 	}
2274 	/* Extend the attribute record to fit the bigger mapping pairs array. */
2275 	attr_len = le32_to_cpu(a->length);
2276 	err = ntfs_attr_record_resize(m, a, mp_size +
2277 			le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
2278 	if (unlikely(err)) {
2279 		BUG_ON(err != -ENOSPC);
2280 		// TODO: Deal with this by moving this extent to a new mft
2281 		// record or by starting a new extent in a new mft record,
2282 		// possibly by extending this extent partially and filling it
2283 		// and creating a new extent for the remainder, or by making
2284 		// other attributes non-resident and/or by moving other
2285 		// attributes out of this mft record.
2286 		if (start < 0 || start >= allocated_size)
2287 			ntfs_error(vol->sb, "Not enough space in the mft "
2288 					"record for the extended attribute "
2289 					"record.  This case is not "
2290 					"implemented yet.");
2291 		err = -EOPNOTSUPP;
2292 		goto undo_alloc;
2293 	}
2294 	mp_rebuilt = TRUE;
2295 	/* Generate the mapping pairs array directly into the attr record. */
2296 	err = ntfs_mapping_pairs_build(vol, (u8*)a +
2297 			le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
2298 			mp_size, rl2, ll, -1, NULL);
2299 	if (unlikely(err)) {
2300 		if (start < 0 || start >= allocated_size)
2301 			ntfs_error(vol->sb, "Cannot extend allocation of "
2302 					"inode 0x%lx, attribute type 0x%x, "
2303 					"because building the mapping pairs "
2304 					"failed with error code %i.", vi->i_ino,
2305 					(unsigned)le32_to_cpu(ni->type), err);
2306 		err = -EIO;
2307 		goto undo_alloc;
2308 	}
2309 	/* Update the highest_vcn. */
2310 	a->data.non_resident.highest_vcn = cpu_to_sle64((new_alloc_size >>
2311 			vol->cluster_size_bits) - 1);
2312 	/*
2313 	 * We now have extended the allocated size of the attribute.  Reflect
2314 	 * this in the ntfs_inode structure and the attribute record.
2315 	 */
2316 	if (a->data.non_resident.lowest_vcn) {
2317 		/*
2318 		 * We are not in the first attribute extent, switch to it, but
2319 		 * first ensure the changes will make it to disk later.
2320 		 */
2321 		flush_dcache_mft_record_page(ctx->ntfs_ino);
2322 		mark_mft_record_dirty(ctx->ntfs_ino);
2323 		ntfs_attr_reinit_search_ctx(ctx);
2324 		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
2325 				CASE_SENSITIVE, 0, NULL, 0, ctx);
2326 		if (unlikely(err))
2327 			goto restore_undo_alloc;
2328 		/* @m is not used any more so no need to set it. */
2329 		a = ctx->attr;
2330 	}
2331 	write_lock_irqsave(&ni->size_lock, flags);
2332 	ni->allocated_size = new_alloc_size;
2333 	a->data.non_resident.allocated_size = cpu_to_sle64(new_alloc_size);
2334 	/*
2335 	 * FIXME: This would fail if @ni is a directory, $MFT, or an index,
2336 	 * since those can have sparse/compressed set.  For example can be
2337 	 * set compressed even though it is not compressed itself and in that
2338 	 * case the bit means that files are to be created compressed in the
2339 	 * directory...  At present this is ok as this code is only called for
2340 	 * regular files, and only for their $DATA attribute(s).
2341 	 * FIXME: The calculation is wrong if we created a hole above.  For now
2342 	 * it does not matter as we never create holes.
2343 	 */
2344 	if (NInoSparse(ni) || NInoCompressed(ni)) {
2345 		ni->itype.compressed.size += new_alloc_size - allocated_size;
2346 		a->data.non_resident.compressed_size =
2347 				cpu_to_sle64(ni->itype.compressed.size);
2348 		vi->i_blocks = ni->itype.compressed.size >> 9;
2349 	} else
2350 		vi->i_blocks = new_alloc_size >> 9;
2351 	write_unlock_irqrestore(&ni->size_lock, flags);
2352 alloc_done:
2353 	if (new_data_size >= 0) {
2354 		BUG_ON(new_data_size <
2355 				sle64_to_cpu(a->data.non_resident.data_size));
2356 		a->data.non_resident.data_size = cpu_to_sle64(new_data_size);
2357 	}
2358 flush_done:
2359 	/* Ensure the changes make it to disk. */
2360 	flush_dcache_mft_record_page(ctx->ntfs_ino);
2361 	mark_mft_record_dirty(ctx->ntfs_ino);
2362 done:
2363 	ntfs_attr_put_search_ctx(ctx);
2364 	unmap_mft_record(base_ni);
2365 	up_write(&ni->runlist.lock);
2366 	ntfs_debug("Done, new_allocated_size 0x%llx.",
2367 			(unsigned long long)new_alloc_size);
2368 	return new_alloc_size;
2369 restore_undo_alloc:
2370 	if (start < 0 || start >= allocated_size)
2371 		ntfs_error(vol->sb, "Cannot complete extension of allocation "
2372 				"of inode 0x%lx, attribute type 0x%x, because "
2373 				"lookup of first attribute extent failed with "
2374 				"error code %i.", vi->i_ino,
2375 				(unsigned)le32_to_cpu(ni->type), err);
2376 	if (err == -ENOENT)
2377 		err = -EIO;
2378 	ntfs_attr_reinit_search_ctx(ctx);
2379 	if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len, CASE_SENSITIVE,
2380 			allocated_size >> vol->cluster_size_bits, NULL, 0,
2381 			ctx)) {
2382 		ntfs_error(vol->sb, "Failed to find last attribute extent of "
2383 				"attribute in error code path.  Run chkdsk to "
2384 				"recover.");
2385 		write_lock_irqsave(&ni->size_lock, flags);
2386 		ni->allocated_size = new_alloc_size;
2387 		/*
2388 		 * FIXME: This would fail if @ni is a directory...  See above.
2389 		 * FIXME: The calculation is wrong if we created a hole above.
2390 		 * For now it does not matter as we never create holes.
2391 		 */
2392 		if (NInoSparse(ni) || NInoCompressed(ni)) {
2393 			ni->itype.compressed.size += new_alloc_size -
2394 					allocated_size;
2395 			vi->i_blocks = ni->itype.compressed.size >> 9;
2396 		} else
2397 			vi->i_blocks = new_alloc_size >> 9;
2398 		write_unlock_irqrestore(&ni->size_lock, flags);
2399 		ntfs_attr_put_search_ctx(ctx);
2400 		unmap_mft_record(base_ni);
2401 		up_write(&ni->runlist.lock);
2402 		/*
2403 		 * The only thing that is now wrong is the allocated size of the
2404 		 * base attribute extent which chkdsk should be able to fix.
2405 		 */
2406 		NVolSetErrors(vol);
2407 		return err;
2408 	}
2409 	ctx->attr->data.non_resident.highest_vcn = cpu_to_sle64(
2410 			(allocated_size >> vol->cluster_size_bits) - 1);
2411 undo_alloc:
2412 	ll = allocated_size >> vol->cluster_size_bits;
2413 	if (ntfs_cluster_free(ni, ll, -1, ctx) < 0) {
2414 		ntfs_error(vol->sb, "Failed to release allocated cluster(s) "
2415 				"in error code path.  Run chkdsk to recover "
2416 				"the lost cluster(s).");
2417 		NVolSetErrors(vol);
2418 	}
2419 	m = ctx->mrec;
2420 	a = ctx->attr;
2421 	/*
2422 	 * If the runlist truncation fails and/or the search context is no
2423 	 * longer valid, we cannot resize the attribute record or build the
2424 	 * mapping pairs array thus we mark the inode bad so that no access to
2425 	 * the freed clusters can happen.
2426 	 */
2427 	if (ntfs_rl_truncate_nolock(vol, &ni->runlist, ll) || IS_ERR(m)) {
2428 		ntfs_error(vol->sb, "Failed to %s in error code path.  Run "
2429 				"chkdsk to recover.", IS_ERR(m) ?
2430 				"restore attribute search context" :
2431 				"truncate attribute runlist");
2432 		make_bad_inode(vi);
2433 		make_bad_inode(VFS_I(base_ni));
2434 		NVolSetErrors(vol);
2435 	} else if (mp_rebuilt) {
2436 		if (ntfs_attr_record_resize(m, a, attr_len)) {
2437 			ntfs_error(vol->sb, "Failed to restore attribute "
2438 					"record in error code path.  Run "
2439 					"chkdsk to recover.");
2440 			make_bad_inode(vi);
2441 			make_bad_inode(VFS_I(base_ni));
2442 			NVolSetErrors(vol);
2443 		} else /* if (success) */ {
2444 			if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
2445 					a->data.non_resident.
2446 					mapping_pairs_offset), attr_len -
2447 					le16_to_cpu(a->data.non_resident.
2448 					mapping_pairs_offset), rl2, ll, -1,
2449 					NULL)) {
2450 				ntfs_error(vol->sb, "Failed to restore "
2451 						"mapping pairs array in error "
2452 						"code path.  Run chkdsk to "
2453 						"recover.");
2454 				make_bad_inode(vi);
2455 				make_bad_inode(VFS_I(base_ni));
2456 				NVolSetErrors(vol);
2457 			}
2458 			flush_dcache_mft_record_page(ctx->ntfs_ino);
2459 			mark_mft_record_dirty(ctx->ntfs_ino);
2460 		}
2461 	}
2462 err_out:
2463 	if (ctx)
2464 		ntfs_attr_put_search_ctx(ctx);
2465 	if (m)
2466 		unmap_mft_record(base_ni);
2467 	up_write(&ni->runlist.lock);
2468 conv_err_out:
2469 	ntfs_debug("Failed.  Returning error code %i.", err);
2470 	return err;
2471 }
2472 
2473 /**
2474  * ntfs_attr_set - fill (a part of) an attribute with a byte
2475  * @ni:		ntfs inode describing the attribute to fill
2476  * @ofs:	offset inside the attribute at which to start to fill
2477  * @cnt:	number of bytes to fill
2478  * @val:	the unsigned 8-bit value with which to fill the attribute
2479  *
2480  * Fill @cnt bytes of the attribute described by the ntfs inode @ni starting at
2481  * byte offset @ofs inside the attribute with the constant byte @val.
2482  *
2483  * This function is effectively like memset() applied to an ntfs attribute.
2484  * Note thie function actually only operates on the page cache pages belonging
2485  * to the ntfs attribute and it marks them dirty after doing the memset().
2486  * Thus it relies on the vm dirty page write code paths to cause the modified
2487  * pages to be written to the mft record/disk.
2488  *
2489  * Return 0 on success and -errno on error.  An error code of -ESPIPE means
2490  * that @ofs + @cnt were outside the end of the attribute and no write was
2491  * performed.
2492  */
2493 int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
2494 {
2495 	ntfs_volume *vol = ni->vol;
2496 	struct address_space *mapping;
2497 	struct page *page;
2498 	u8 *kaddr;
2499 	pgoff_t idx, end;
2500 	unsigned int start_ofs, end_ofs, size;
2501 
2502 	ntfs_debug("Entering for ofs 0x%llx, cnt 0x%llx, val 0x%hx.",
2503 			(long long)ofs, (long long)cnt, val);
2504 	BUG_ON(ofs < 0);
2505 	BUG_ON(cnt < 0);
2506 	if (!cnt)
2507 		goto done;
2508 	/*
2509 	 * FIXME: Compressed and encrypted attributes are not supported when
2510 	 * writing and we should never have gotten here for them.
2511 	 */
2512 	BUG_ON(NInoCompressed(ni));
2513 	BUG_ON(NInoEncrypted(ni));
2514 	mapping = VFS_I(ni)->i_mapping;
2515 	/* Work out the starting index and page offset. */
2516 	idx = ofs >> PAGE_CACHE_SHIFT;
2517 	start_ofs = ofs & ~PAGE_CACHE_MASK;
2518 	/* Work out the ending index and page offset. */
2519 	end = ofs + cnt;
2520 	end_ofs = end & ~PAGE_CACHE_MASK;
2521 	/* If the end is outside the inode size return -ESPIPE. */
2522 	if (unlikely(end > i_size_read(VFS_I(ni)))) {
2523 		ntfs_error(vol->sb, "Request exceeds end of attribute.");
2524 		return -ESPIPE;
2525 	}
2526 	end >>= PAGE_CACHE_SHIFT;
2527 	/* If there is a first partial page, need to do it the slow way. */
2528 	if (start_ofs) {
2529 		page = read_cache_page(mapping, idx,
2530 				(filler_t*)mapping->a_ops->readpage, NULL);
2531 		if (IS_ERR(page)) {
2532 			ntfs_error(vol->sb, "Failed to read first partial "
2533 					"page (sync error, index 0x%lx).", idx);
2534 			return PTR_ERR(page);
2535 		}
2536 		wait_on_page_locked(page);
2537 		if (unlikely(!PageUptodate(page))) {
2538 			ntfs_error(vol->sb, "Failed to read first partial page "
2539 					"(async error, index 0x%lx).", idx);
2540 			page_cache_release(page);
2541 			return PTR_ERR(page);
2542 		}
2543 		/*
2544 		 * If the last page is the same as the first page, need to
2545 		 * limit the write to the end offset.
2546 		 */
2547 		size = PAGE_CACHE_SIZE;
2548 		if (idx == end)
2549 			size = end_ofs;
2550 		kaddr = kmap_atomic(page, KM_USER0);
2551 		memset(kaddr + start_ofs, val, size - start_ofs);
2552 		flush_dcache_page(page);
2553 		kunmap_atomic(kaddr, KM_USER0);
2554 		set_page_dirty(page);
2555 		page_cache_release(page);
2556 		if (idx == end)
2557 			goto done;
2558 		idx++;
2559 	}
2560 	/* Do the whole pages the fast way. */
2561 	for (; idx < end; idx++) {
2562 		/* Find or create the current page.  (The page is locked.) */
2563 		page = grab_cache_page(mapping, idx);
2564 		if (unlikely(!page)) {
2565 			ntfs_error(vol->sb, "Insufficient memory to grab "
2566 					"page (index 0x%lx).", idx);
2567 			return -ENOMEM;
2568 		}
2569 		kaddr = kmap_atomic(page, KM_USER0);
2570 		memset(kaddr, val, PAGE_CACHE_SIZE);
2571 		flush_dcache_page(page);
2572 		kunmap_atomic(kaddr, KM_USER0);
2573 		/*
2574 		 * If the page has buffers, mark them uptodate since buffer
2575 		 * state and not page state is definitive in 2.6 kernels.
2576 		 */
2577 		if (page_has_buffers(page)) {
2578 			struct buffer_head *bh, *head;
2579 
2580 			bh = head = page_buffers(page);
2581 			do {
2582 				set_buffer_uptodate(bh);
2583 			} while ((bh = bh->b_this_page) != head);
2584 		}
2585 		/* Now that buffers are uptodate, set the page uptodate, too. */
2586 		SetPageUptodate(page);
2587 		/*
2588 		 * Set the page and all its buffers dirty and mark the inode
2589 		 * dirty, too.  The VM will write the page later on.
2590 		 */
2591 		set_page_dirty(page);
2592 		/* Finally unlock and release the page. */
2593 		unlock_page(page);
2594 		page_cache_release(page);
2595 		balance_dirty_pages_ratelimited(mapping);
2596 		cond_resched();
2597 	}
2598 	/* If there is a last partial page, need to do it the slow way. */
2599 	if (end_ofs) {
2600 		page = read_cache_page(mapping, idx,
2601 				(filler_t*)mapping->a_ops->readpage, NULL);
2602 		if (IS_ERR(page)) {
2603 			ntfs_error(vol->sb, "Failed to read last partial page "
2604 					"(sync error, index 0x%lx).", idx);
2605 			return PTR_ERR(page);
2606 		}
2607 		wait_on_page_locked(page);
2608 		if (unlikely(!PageUptodate(page))) {
2609 			ntfs_error(vol->sb, "Failed to read last partial page "
2610 					"(async error, index 0x%lx).", idx);
2611 			page_cache_release(page);
2612 			return PTR_ERR(page);
2613 		}
2614 		kaddr = kmap_atomic(page, KM_USER0);
2615 		memset(kaddr, val, end_ofs);
2616 		flush_dcache_page(page);
2617 		kunmap_atomic(kaddr, KM_USER0);
2618 		set_page_dirty(page);
2619 		page_cache_release(page);
2620 	}
2621 done:
2622 	ntfs_debug("Done.");
2623 	return 0;
2624 }
2625 
2626 #endif /* NTFS_RW */
2627