1 /*
2  * This file is part of UBIFS.
3  *
4  * Copyright (C) 2006-2008 Nokia Corporation.
5  * Copyright (C) 2006, 2007 University of Szeged, Hungary
6  *
7  * This program is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU General Public License version 2 as published by
9  * the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
14  * more details.
15  *
16  * You should have received a copy of the GNU General Public License along with
17  * this program; if not, write to the Free Software Foundation, Inc., 51
18  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19  *
20  * Authors: Artem Bityutskiy (Битюцкий Артём)
21  *          Adrian Hunter
22  *          Zoltan Sogor
23  */
24 
25 /*
26  * This file implements UBIFS I/O subsystem which provides various I/O-related
27  * helper functions (reading/writing/checking/validating nodes) and implements
28  * write-buffering support. Write buffers help to save space which otherwise
29  * would have been wasted for padding to the nearest minimal I/O unit boundary.
30  * Instead, data first goes to the write-buffer and is flushed when the
31  * buffer is full or when it is not used for some time (by timer). This is
32  * similar to the mechanism is used by JFFS2.
33  *
34  * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
35  * write size (@c->max_write_size). The latter is the maximum amount of bytes
36  * the underlying flash is able to program at a time, and writing in
37  * @c->max_write_size units should presumably be faster. Obviously,
38  * @c->min_io_size <= @c->max_write_size. Write-buffers are of
39  * @c->max_write_size bytes in size for maximum performance. However, when a
40  * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
41  * boundary) which contains data is written, not the whole write-buffer,
42  * because this is more space-efficient.
43  *
44  * This optimization adds few complications to the code. Indeed, on the one
45  * hand, we want to write in optimal @c->max_write_size bytes chunks, which
46  * also means aligning writes at the @c->max_write_size bytes offsets. On the
47  * other hand, we do not want to waste space when synchronizing the write
48  * buffer, so during synchronization we writes in smaller chunks. And this makes
49  * the next write offset to be not aligned to @c->max_write_size bytes. So the
50  * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
51  * to @c->max_write_size bytes again. We do this by temporarily shrinking
52  * write-buffer size (@wbuf->size).
53  *
54  * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
55  * mutexes defined inside these objects. Since sometimes upper-level code
56  * has to lock the write-buffer (e.g. journal space reservation code), many
57  * functions related to write-buffers have "nolock" suffix which means that the
58  * caller has to lock the write-buffer before calling this function.
59  *
60  * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
61  * aligned, UBIFS starts the next node from the aligned address, and the padded
62  * bytes may contain any rubbish. In other words, UBIFS does not put padding
63  * bytes in those small gaps. Common headers of nodes store real node lengths,
64  * not aligned lengths. Indexing nodes also store real lengths in branches.
65  *
66  * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
67  * uses padding nodes or padding bytes, if the padding node does not fit.
68  *
69  * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
70  * they are read from the flash media.
71  */
72 
73 #include <linux/crc32.h>
74 #include <linux/slab.h>
75 #include "ubifs.h"
76 
77 /**
78  * ubifs_ro_mode - switch UBIFS to read read-only mode.
79  * @c: UBIFS file-system description object
80  * @err: error code which is the reason of switching to R/O mode
81  */
ubifs_ro_mode(struct ubifs_info * c,int err)82 void ubifs_ro_mode(struct ubifs_info *c, int err)
83 {
84 	if (!c->ro_error) {
85 		c->ro_error = 1;
86 		c->no_chk_data_crc = 0;
87 		c->vfs_sb->s_flags |= MS_RDONLY;
88 		ubifs_warn("switched to read-only mode, error %d", err);
89 		dump_stack();
90 	}
91 }
92 
93 /*
94  * Below are simple wrappers over UBI I/O functions which include some
95  * additional checks and UBIFS debugging stuff. See corresponding UBI function
96  * for more information.
97  */
98 
ubifs_leb_read(const struct ubifs_info * c,int lnum,void * buf,int offs,int len,int even_ebadmsg)99 int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
100 		   int len, int even_ebadmsg)
101 {
102 	int err;
103 
104 	err = ubi_read(c->ubi, lnum, buf, offs, len);
105 	/*
106 	 * In case of %-EBADMSG print the error message only if the
107 	 * @even_ebadmsg is true.
108 	 */
109 	if (err && (err != -EBADMSG || even_ebadmsg)) {
110 		ubifs_err("reading %d bytes from LEB %d:%d failed, error %d",
111 			  len, lnum, offs, err);
112 		dbg_dump_stack();
113 	}
114 	return err;
115 }
116 
ubifs_leb_write(struct ubifs_info * c,int lnum,const void * buf,int offs,int len,int dtype)117 int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
118 		    int len, int dtype)
119 {
120 	int err;
121 
122 	ubifs_assert(!c->ro_media && !c->ro_mount);
123 	if (c->ro_error)
124 		return -EROFS;
125 	if (!dbg_is_tst_rcvry(c))
126 		err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
127 	else
128 		err = dbg_leb_write(c, lnum, buf, offs, len, dtype);
129 	if (err) {
130 		ubifs_err("writing %d bytes to LEB %d:%d failed, error %d",
131 			  len, lnum, offs, err);
132 		ubifs_ro_mode(c, err);
133 		dbg_dump_stack();
134 	}
135 	return err;
136 }
137 
ubifs_leb_change(struct ubifs_info * c,int lnum,const void * buf,int len,int dtype)138 int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len,
139 		     int dtype)
140 {
141 	int err;
142 
143 	ubifs_assert(!c->ro_media && !c->ro_mount);
144 	if (c->ro_error)
145 		return -EROFS;
146 	if (!dbg_is_tst_rcvry(c))
147 		err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
148 	else
149 		err = dbg_leb_change(c, lnum, buf, len, dtype);
150 	if (err) {
151 		ubifs_err("changing %d bytes in LEB %d failed, error %d",
152 			  len, lnum, err);
153 		ubifs_ro_mode(c, err);
154 		dbg_dump_stack();
155 	}
156 	return err;
157 }
158 
ubifs_leb_unmap(struct ubifs_info * c,int lnum)159 int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
160 {
161 	int err;
162 
163 	ubifs_assert(!c->ro_media && !c->ro_mount);
164 	if (c->ro_error)
165 		return -EROFS;
166 	if (!dbg_is_tst_rcvry(c))
167 		err = ubi_leb_unmap(c->ubi, lnum);
168 	else
169 		err = dbg_leb_unmap(c, lnum);
170 	if (err) {
171 		ubifs_err("unmap LEB %d failed, error %d", lnum, err);
172 		ubifs_ro_mode(c, err);
173 		dbg_dump_stack();
174 	}
175 	return err;
176 }
177 
ubifs_leb_map(struct ubifs_info * c,int lnum,int dtype)178 int ubifs_leb_map(struct ubifs_info *c, int lnum, int dtype)
179 {
180 	int err;
181 
182 	ubifs_assert(!c->ro_media && !c->ro_mount);
183 	if (c->ro_error)
184 		return -EROFS;
185 	if (!dbg_is_tst_rcvry(c))
186 		err = ubi_leb_map(c->ubi, lnum, dtype);
187 	else
188 		err = dbg_leb_map(c, lnum, dtype);
189 	if (err) {
190 		ubifs_err("mapping LEB %d failed, error %d", lnum, err);
191 		ubifs_ro_mode(c, err);
192 		dbg_dump_stack();
193 	}
194 	return err;
195 }
196 
ubifs_is_mapped(const struct ubifs_info * c,int lnum)197 int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
198 {
199 	int err;
200 
201 	err = ubi_is_mapped(c->ubi, lnum);
202 	if (err < 0) {
203 		ubifs_err("ubi_is_mapped failed for LEB %d, error %d",
204 			  lnum, err);
205 		dbg_dump_stack();
206 	}
207 	return err;
208 }
209 
210 /**
211  * ubifs_check_node - check node.
212  * @c: UBIFS file-system description object
213  * @buf: node to check
214  * @lnum: logical eraseblock number
215  * @offs: offset within the logical eraseblock
216  * @quiet: print no messages
217  * @must_chk_crc: indicates whether to always check the CRC
218  *
219  * This function checks node magic number and CRC checksum. This function also
220  * validates node length to prevent UBIFS from becoming crazy when an attacker
221  * feeds it a file-system image with incorrect nodes. For example, too large
222  * node length in the common header could cause UBIFS to read memory outside of
223  * allocated buffer when checking the CRC checksum.
224  *
225  * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
226  * true, which is controlled by corresponding UBIFS mount option. However, if
227  * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
228  * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
229  * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
230  * is checked. This is because during mounting or re-mounting from R/O mode to
231  * R/W mode we may read journal nodes (when replying the journal or doing the
232  * recovery) and the journal nodes may potentially be corrupted, so checking is
233  * required.
234  *
235  * This function returns zero in case of success and %-EUCLEAN in case of bad
236  * CRC or magic.
237  */
ubifs_check_node(const struct ubifs_info * c,const void * buf,int lnum,int offs,int quiet,int must_chk_crc)238 int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
239 		     int offs, int quiet, int must_chk_crc)
240 {
241 	int err = -EINVAL, type, node_len;
242 	uint32_t crc, node_crc, magic;
243 	const struct ubifs_ch *ch = buf;
244 
245 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
246 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
247 
248 	magic = le32_to_cpu(ch->magic);
249 	if (magic != UBIFS_NODE_MAGIC) {
250 		if (!quiet)
251 			ubifs_err("bad magic %#08x, expected %#08x",
252 				  magic, UBIFS_NODE_MAGIC);
253 		err = -EUCLEAN;
254 		goto out;
255 	}
256 
257 	type = ch->node_type;
258 	if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
259 		if (!quiet)
260 			ubifs_err("bad node type %d", type);
261 		goto out;
262 	}
263 
264 	node_len = le32_to_cpu(ch->len);
265 	if (node_len + offs > c->leb_size)
266 		goto out_len;
267 
268 	if (c->ranges[type].max_len == 0) {
269 		if (node_len != c->ranges[type].len)
270 			goto out_len;
271 	} else if (node_len < c->ranges[type].min_len ||
272 		   node_len > c->ranges[type].max_len)
273 		goto out_len;
274 
275 	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
276 	    !c->remounting_rw && c->no_chk_data_crc)
277 		return 0;
278 
279 	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
280 	node_crc = le32_to_cpu(ch->crc);
281 	if (crc != node_crc) {
282 		if (!quiet)
283 			ubifs_err("bad CRC: calculated %#08x, read %#08x",
284 				  crc, node_crc);
285 		err = -EUCLEAN;
286 		goto out;
287 	}
288 
289 	return 0;
290 
291 out_len:
292 	if (!quiet)
293 		ubifs_err("bad node length %d", node_len);
294 out:
295 	if (!quiet) {
296 		ubifs_err("bad node at LEB %d:%d", lnum, offs);
297 		dbg_dump_node(c, buf);
298 		dbg_dump_stack();
299 	}
300 	return err;
301 }
302 
303 /**
304  * ubifs_pad - pad flash space.
305  * @c: UBIFS file-system description object
306  * @buf: buffer to put padding to
307  * @pad: how many bytes to pad
308  *
309  * The flash media obliges us to write only in chunks of %c->min_io_size and
310  * when we have to write less data we add padding node to the write-buffer and
311  * pad it to the next minimal I/O unit's boundary. Padding nodes help when the
312  * media is being scanned. If the amount of wasted space is not enough to fit a
313  * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
314  * pattern (%UBIFS_PADDING_BYTE).
315  *
316  * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
317  * used.
318  */
ubifs_pad(const struct ubifs_info * c,void * buf,int pad)319 void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
320 {
321 	uint32_t crc;
322 
323 	ubifs_assert(pad >= 0 && !(pad & 7));
324 
325 	if (pad >= UBIFS_PAD_NODE_SZ) {
326 		struct ubifs_ch *ch = buf;
327 		struct ubifs_pad_node *pad_node = buf;
328 
329 		ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
330 		ch->node_type = UBIFS_PAD_NODE;
331 		ch->group_type = UBIFS_NO_NODE_GROUP;
332 		ch->padding[0] = ch->padding[1] = 0;
333 		ch->sqnum = 0;
334 		ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
335 		pad -= UBIFS_PAD_NODE_SZ;
336 		pad_node->pad_len = cpu_to_le32(pad);
337 		crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
338 		ch->crc = cpu_to_le32(crc);
339 		memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
340 	} else if (pad > 0)
341 		/* Too little space, padding node won't fit */
342 		memset(buf, UBIFS_PADDING_BYTE, pad);
343 }
344 
345 /**
346  * next_sqnum - get next sequence number.
347  * @c: UBIFS file-system description object
348  */
next_sqnum(struct ubifs_info * c)349 static unsigned long long next_sqnum(struct ubifs_info *c)
350 {
351 	unsigned long long sqnum;
352 
353 	spin_lock(&c->cnt_lock);
354 	sqnum = ++c->max_sqnum;
355 	spin_unlock(&c->cnt_lock);
356 
357 	if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
358 		if (sqnum >= SQNUM_WATERMARK) {
359 			ubifs_err("sequence number overflow %llu, end of life",
360 				  sqnum);
361 			ubifs_ro_mode(c, -EINVAL);
362 		}
363 		ubifs_warn("running out of sequence numbers, end of life soon");
364 	}
365 
366 	return sqnum;
367 }
368 
369 /**
370  * ubifs_prepare_node - prepare node to be written to flash.
371  * @c: UBIFS file-system description object
372  * @node: the node to pad
373  * @len: node length
374  * @pad: if the buffer has to be padded
375  *
376  * This function prepares node at @node to be written to the media - it
377  * calculates node CRC, fills the common header, and adds proper padding up to
378  * the next minimum I/O unit if @pad is not zero.
379  */
ubifs_prepare_node(struct ubifs_info * c,void * node,int len,int pad)380 void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
381 {
382 	uint32_t crc;
383 	struct ubifs_ch *ch = node;
384 	unsigned long long sqnum = next_sqnum(c);
385 
386 	ubifs_assert(len >= UBIFS_CH_SZ);
387 
388 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
389 	ch->len = cpu_to_le32(len);
390 	ch->group_type = UBIFS_NO_NODE_GROUP;
391 	ch->sqnum = cpu_to_le64(sqnum);
392 	ch->padding[0] = ch->padding[1] = 0;
393 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
394 	ch->crc = cpu_to_le32(crc);
395 
396 	if (pad) {
397 		len = ALIGN(len, 8);
398 		pad = ALIGN(len, c->min_io_size) - len;
399 		ubifs_pad(c, node + len, pad);
400 	}
401 }
402 
403 /**
404  * ubifs_prep_grp_node - prepare node of a group to be written to flash.
405  * @c: UBIFS file-system description object
406  * @node: the node to pad
407  * @len: node length
408  * @last: indicates the last node of the group
409  *
410  * This function prepares node at @node to be written to the media - it
411  * calculates node CRC and fills the common header.
412  */
ubifs_prep_grp_node(struct ubifs_info * c,void * node,int len,int last)413 void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
414 {
415 	uint32_t crc;
416 	struct ubifs_ch *ch = node;
417 	unsigned long long sqnum = next_sqnum(c);
418 
419 	ubifs_assert(len >= UBIFS_CH_SZ);
420 
421 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
422 	ch->len = cpu_to_le32(len);
423 	if (last)
424 		ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
425 	else
426 		ch->group_type = UBIFS_IN_NODE_GROUP;
427 	ch->sqnum = cpu_to_le64(sqnum);
428 	ch->padding[0] = ch->padding[1] = 0;
429 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
430 	ch->crc = cpu_to_le32(crc);
431 }
432 
433 /**
434  * wbuf_timer_callback - write-buffer timer callback function.
435  * @data: timer data (write-buffer descriptor)
436  *
437  * This function is called when the write-buffer timer expires.
438  */
wbuf_timer_callback_nolock(struct hrtimer * timer)439 static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
440 {
441 	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
442 
443 	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
444 	wbuf->need_sync = 1;
445 	wbuf->c->need_wbuf_sync = 1;
446 	ubifs_wake_up_bgt(wbuf->c);
447 	return HRTIMER_NORESTART;
448 }
449 
450 /**
451  * new_wbuf_timer - start new write-buffer timer.
452  * @wbuf: write-buffer descriptor
453  */
new_wbuf_timer_nolock(struct ubifs_wbuf * wbuf)454 static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
455 {
456 	ubifs_assert(!hrtimer_active(&wbuf->timer));
457 
458 	if (wbuf->no_timer)
459 		return;
460 	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
461 	       dbg_jhead(wbuf->jhead),
462 	       div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
463 	       div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
464 		       USEC_PER_SEC));
465 	hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
466 			       HRTIMER_MODE_REL);
467 }
468 
469 /**
470  * cancel_wbuf_timer - cancel write-buffer timer.
471  * @wbuf: write-buffer descriptor
472  */
cancel_wbuf_timer_nolock(struct ubifs_wbuf * wbuf)473 static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
474 {
475 	if (wbuf->no_timer)
476 		return;
477 	wbuf->need_sync = 0;
478 	hrtimer_cancel(&wbuf->timer);
479 }
480 
481 /**
482  * ubifs_wbuf_sync_nolock - synchronize write-buffer.
483  * @wbuf: write-buffer to synchronize
484  *
485  * This function synchronizes write-buffer @buf and returns zero in case of
486  * success or a negative error code in case of failure.
487  *
488  * Note, although write-buffers are of @c->max_write_size, this function does
489  * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
490  * if the write-buffer is only partially filled with data, only the used part
491  * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
492  * This way we waste less space.
493  */
ubifs_wbuf_sync_nolock(struct ubifs_wbuf * wbuf)494 int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
495 {
496 	struct ubifs_info *c = wbuf->c;
497 	int err, dirt, sync_len;
498 
499 	cancel_wbuf_timer_nolock(wbuf);
500 	if (!wbuf->used || wbuf->lnum == -1)
501 		/* Write-buffer is empty or not seeked */
502 		return 0;
503 
504 	dbg_io("LEB %d:%d, %d bytes, jhead %s",
505 	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
506 	ubifs_assert(!(wbuf->avail & 7));
507 	ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
508 	ubifs_assert(wbuf->size >= c->min_io_size);
509 	ubifs_assert(wbuf->size <= c->max_write_size);
510 	ubifs_assert(wbuf->size % c->min_io_size == 0);
511 	ubifs_assert(!c->ro_media && !c->ro_mount);
512 	if (c->leb_size - wbuf->offs >= c->max_write_size)
513 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
514 
515 	if (c->ro_error)
516 		return -EROFS;
517 
518 	/*
519 	 * Do not write whole write buffer but write only the minimum necessary
520 	 * amount of min. I/O units.
521 	 */
522 	sync_len = ALIGN(wbuf->used, c->min_io_size);
523 	dirt = sync_len - wbuf->used;
524 	if (dirt)
525 		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
526 	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len,
527 			      wbuf->dtype);
528 	if (err)
529 		return err;
530 
531 	spin_lock(&wbuf->lock);
532 	wbuf->offs += sync_len;
533 	/*
534 	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
535 	 * But our goal is to optimize writes and make sure we write in
536 	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
537 	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
538 	 * sure that @wbuf->offs + @wbuf->size is aligned to
539 	 * @c->max_write_size. This way we make sure that after next
540 	 * write-buffer flush we are again at the optimal offset (aligned to
541 	 * @c->max_write_size).
542 	 */
543 	if (c->leb_size - wbuf->offs < c->max_write_size)
544 		wbuf->size = c->leb_size - wbuf->offs;
545 	else if (wbuf->offs & (c->max_write_size - 1))
546 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
547 	else
548 		wbuf->size = c->max_write_size;
549 	wbuf->avail = wbuf->size;
550 	wbuf->used = 0;
551 	wbuf->next_ino = 0;
552 	spin_unlock(&wbuf->lock);
553 
554 	if (wbuf->sync_callback)
555 		err = wbuf->sync_callback(c, wbuf->lnum,
556 					  c->leb_size - wbuf->offs, dirt);
557 	return err;
558 }
559 
560 /**
561  * ubifs_wbuf_seek_nolock - seek write-buffer.
562  * @wbuf: write-buffer
563  * @lnum: logical eraseblock number to seek to
564  * @offs: logical eraseblock offset to seek to
565  * @dtype: data type
566  *
567  * This function targets the write-buffer to logical eraseblock @lnum:@offs.
568  * The write-buffer has to be empty. Returns zero in case of success and a
569  * negative error code in case of failure.
570  */
ubifs_wbuf_seek_nolock(struct ubifs_wbuf * wbuf,int lnum,int offs,int dtype)571 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs,
572 			   int dtype)
573 {
574 	const struct ubifs_info *c = wbuf->c;
575 
576 	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
577 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
578 	ubifs_assert(offs >= 0 && offs <= c->leb_size);
579 	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
580 	ubifs_assert(lnum != wbuf->lnum);
581 	ubifs_assert(wbuf->used == 0);
582 
583 	spin_lock(&wbuf->lock);
584 	wbuf->lnum = lnum;
585 	wbuf->offs = offs;
586 	if (c->leb_size - wbuf->offs < c->max_write_size)
587 		wbuf->size = c->leb_size - wbuf->offs;
588 	else if (wbuf->offs & (c->max_write_size - 1))
589 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
590 	else
591 		wbuf->size = c->max_write_size;
592 	wbuf->avail = wbuf->size;
593 	wbuf->used = 0;
594 	spin_unlock(&wbuf->lock);
595 	wbuf->dtype = dtype;
596 
597 	return 0;
598 }
599 
600 /**
601  * ubifs_bg_wbufs_sync - synchronize write-buffers.
602  * @c: UBIFS file-system description object
603  *
604  * This function is called by background thread to synchronize write-buffers.
605  * Returns zero in case of success and a negative error code in case of
606  * failure.
607  */
ubifs_bg_wbufs_sync(struct ubifs_info * c)608 int ubifs_bg_wbufs_sync(struct ubifs_info *c)
609 {
610 	int err, i;
611 
612 	ubifs_assert(!c->ro_media && !c->ro_mount);
613 	if (!c->need_wbuf_sync)
614 		return 0;
615 	c->need_wbuf_sync = 0;
616 
617 	if (c->ro_error) {
618 		err = -EROFS;
619 		goto out_timers;
620 	}
621 
622 	dbg_io("synchronize");
623 	for (i = 0; i < c->jhead_cnt; i++) {
624 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
625 
626 		cond_resched();
627 
628 		/*
629 		 * If the mutex is locked then wbuf is being changed, so
630 		 * synchronization is not necessary.
631 		 */
632 		if (mutex_is_locked(&wbuf->io_mutex))
633 			continue;
634 
635 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
636 		if (!wbuf->need_sync) {
637 			mutex_unlock(&wbuf->io_mutex);
638 			continue;
639 		}
640 
641 		err = ubifs_wbuf_sync_nolock(wbuf);
642 		mutex_unlock(&wbuf->io_mutex);
643 		if (err) {
644 			ubifs_err("cannot sync write-buffer, error %d", err);
645 			ubifs_ro_mode(c, err);
646 			goto out_timers;
647 		}
648 	}
649 
650 	return 0;
651 
652 out_timers:
653 	/* Cancel all timers to prevent repeated errors */
654 	for (i = 0; i < c->jhead_cnt; i++) {
655 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
656 
657 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
658 		cancel_wbuf_timer_nolock(wbuf);
659 		mutex_unlock(&wbuf->io_mutex);
660 	}
661 	return err;
662 }
663 
664 /**
665  * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
666  * @wbuf: write-buffer
667  * @buf: node to write
668  * @len: node length
669  *
670  * This function writes data to flash via write-buffer @wbuf. This means that
671  * the last piece of the node won't reach the flash media immediately if it
672  * does not take whole max. write unit (@c->max_write_size). Instead, the node
673  * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
674  * because more data are appended to the write-buffer).
675  *
676  * This function returns zero in case of success and a negative error code in
677  * case of failure. If the node cannot be written because there is no more
678  * space in this logical eraseblock, %-ENOSPC is returned.
679  */
ubifs_wbuf_write_nolock(struct ubifs_wbuf * wbuf,void * buf,int len)680 int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
681 {
682 	struct ubifs_info *c = wbuf->c;
683 	int err, written, n, aligned_len = ALIGN(len, 8);
684 
685 	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
686 	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
687 	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
688 	ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
689 	ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
690 	ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
691 	ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
692 	ubifs_assert(wbuf->size >= c->min_io_size);
693 	ubifs_assert(wbuf->size <= c->max_write_size);
694 	ubifs_assert(wbuf->size % c->min_io_size == 0);
695 	ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
696 	ubifs_assert(!c->ro_media && !c->ro_mount);
697 	ubifs_assert(!c->space_fixup);
698 	if (c->leb_size - wbuf->offs >= c->max_write_size)
699 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
700 
701 	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
702 		err = -ENOSPC;
703 		goto out;
704 	}
705 
706 	cancel_wbuf_timer_nolock(wbuf);
707 
708 	if (c->ro_error)
709 		return -EROFS;
710 
711 	if (aligned_len <= wbuf->avail) {
712 		/*
713 		 * The node is not very large and fits entirely within
714 		 * write-buffer.
715 		 */
716 		memcpy(wbuf->buf + wbuf->used, buf, len);
717 
718 		if (aligned_len == wbuf->avail) {
719 			dbg_io("flush jhead %s wbuf to LEB %d:%d",
720 			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
721 			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
722 					      wbuf->offs, wbuf->size,
723 					      wbuf->dtype);
724 			if (err)
725 				goto out;
726 
727 			spin_lock(&wbuf->lock);
728 			wbuf->offs += wbuf->size;
729 			if (c->leb_size - wbuf->offs >= c->max_write_size)
730 				wbuf->size = c->max_write_size;
731 			else
732 				wbuf->size = c->leb_size - wbuf->offs;
733 			wbuf->avail = wbuf->size;
734 			wbuf->used = 0;
735 			wbuf->next_ino = 0;
736 			spin_unlock(&wbuf->lock);
737 		} else {
738 			spin_lock(&wbuf->lock);
739 			wbuf->avail -= aligned_len;
740 			wbuf->used += aligned_len;
741 			spin_unlock(&wbuf->lock);
742 		}
743 
744 		goto exit;
745 	}
746 
747 	written = 0;
748 
749 	if (wbuf->used) {
750 		/*
751 		 * The node is large enough and does not fit entirely within
752 		 * current available space. We have to fill and flush
753 		 * write-buffer and switch to the next max. write unit.
754 		 */
755 		dbg_io("flush jhead %s wbuf to LEB %d:%d",
756 		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
757 		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
758 		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
759 				      wbuf->size, wbuf->dtype);
760 		if (err)
761 			goto out;
762 
763 		wbuf->offs += wbuf->size;
764 		len -= wbuf->avail;
765 		aligned_len -= wbuf->avail;
766 		written += wbuf->avail;
767 	} else if (wbuf->offs & (c->max_write_size - 1)) {
768 		/*
769 		 * The write-buffer offset is not aligned to
770 		 * @c->max_write_size and @wbuf->size is less than
771 		 * @c->max_write_size. Write @wbuf->size bytes to make sure the
772 		 * following writes are done in optimal @c->max_write_size
773 		 * chunks.
774 		 */
775 		dbg_io("write %d bytes to LEB %d:%d",
776 		       wbuf->size, wbuf->lnum, wbuf->offs);
777 		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
778 				      wbuf->size, wbuf->dtype);
779 		if (err)
780 			goto out;
781 
782 		wbuf->offs += wbuf->size;
783 		len -= wbuf->size;
784 		aligned_len -= wbuf->size;
785 		written += wbuf->size;
786 	}
787 
788 	/*
789 	 * The remaining data may take more whole max. write units, so write the
790 	 * remains multiple to max. write unit size directly to the flash media.
791 	 * We align node length to 8-byte boundary because we anyway flash wbuf
792 	 * if the remaining space is less than 8 bytes.
793 	 */
794 	n = aligned_len >> c->max_write_shift;
795 	if (n) {
796 		n <<= c->max_write_shift;
797 		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
798 		       wbuf->offs);
799 		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
800 				      wbuf->offs, n, wbuf->dtype);
801 		if (err)
802 			goto out;
803 		wbuf->offs += n;
804 		aligned_len -= n;
805 		len -= n;
806 		written += n;
807 	}
808 
809 	spin_lock(&wbuf->lock);
810 	if (aligned_len)
811 		/*
812 		 * And now we have what's left and what does not take whole
813 		 * max. write unit, so write it to the write-buffer and we are
814 		 * done.
815 		 */
816 		memcpy(wbuf->buf, buf + written, len);
817 
818 	if (c->leb_size - wbuf->offs >= c->max_write_size)
819 		wbuf->size = c->max_write_size;
820 	else
821 		wbuf->size = c->leb_size - wbuf->offs;
822 	wbuf->avail = wbuf->size - aligned_len;
823 	wbuf->used = aligned_len;
824 	wbuf->next_ino = 0;
825 	spin_unlock(&wbuf->lock);
826 
827 exit:
828 	if (wbuf->sync_callback) {
829 		int free = c->leb_size - wbuf->offs - wbuf->used;
830 
831 		err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
832 		if (err)
833 			goto out;
834 	}
835 
836 	if (wbuf->used)
837 		new_wbuf_timer_nolock(wbuf);
838 
839 	return 0;
840 
841 out:
842 	ubifs_err("cannot write %d bytes to LEB %d:%d, error %d",
843 		  len, wbuf->lnum, wbuf->offs, err);
844 	dbg_dump_node(c, buf);
845 	dbg_dump_stack();
846 	dbg_dump_leb(c, wbuf->lnum);
847 	return err;
848 }
849 
850 /**
851  * ubifs_write_node - write node to the media.
852  * @c: UBIFS file-system description object
853  * @buf: the node to write
854  * @len: node length
855  * @lnum: logical eraseblock number
856  * @offs: offset within the logical eraseblock
857  * @dtype: node life-time hint (%UBI_LONGTERM, %UBI_SHORTTERM, %UBI_UNKNOWN)
858  *
859  * This function automatically fills node magic number, assigns sequence
860  * number, and calculates node CRC checksum. The length of the @buf buffer has
861  * to be aligned to the minimal I/O unit size. This function automatically
862  * appends padding node and padding bytes if needed. Returns zero in case of
863  * success and a negative error code in case of failure.
864  */
ubifs_write_node(struct ubifs_info * c,void * buf,int len,int lnum,int offs,int dtype)865 int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
866 		     int offs, int dtype)
867 {
868 	int err, buf_len = ALIGN(len, c->min_io_size);
869 
870 	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
871 	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
872 	       buf_len);
873 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
874 	ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
875 	ubifs_assert(!c->ro_media && !c->ro_mount);
876 	ubifs_assert(!c->space_fixup);
877 
878 	if (c->ro_error)
879 		return -EROFS;
880 
881 	ubifs_prepare_node(c, buf, len, 1);
882 	err = ubifs_leb_write(c, lnum, buf, offs, buf_len, dtype);
883 	if (err)
884 		dbg_dump_node(c, buf);
885 
886 	return err;
887 }
888 
889 /**
890  * ubifs_read_node_wbuf - read node from the media or write-buffer.
891  * @wbuf: wbuf to check for un-written data
892  * @buf: buffer to read to
893  * @type: node type
894  * @len: node length
895  * @lnum: logical eraseblock number
896  * @offs: offset within the logical eraseblock
897  *
898  * This function reads a node of known type and length, checks it and stores
899  * in @buf. If the node partially or fully sits in the write-buffer, this
900  * function takes data from the buffer, otherwise it reads the flash media.
901  * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
902  * error code in case of failure.
903  */
ubifs_read_node_wbuf(struct ubifs_wbuf * wbuf,void * buf,int type,int len,int lnum,int offs)904 int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
905 			 int lnum, int offs)
906 {
907 	const struct ubifs_info *c = wbuf->c;
908 	int err, rlen, overlap;
909 	struct ubifs_ch *ch = buf;
910 
911 	dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
912 	       dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
913 	ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
914 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
915 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
916 
917 	spin_lock(&wbuf->lock);
918 	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
919 	if (!overlap) {
920 		/* We may safely unlock the write-buffer and read the data */
921 		spin_unlock(&wbuf->lock);
922 		return ubifs_read_node(c, buf, type, len, lnum, offs);
923 	}
924 
925 	/* Don't read under wbuf */
926 	rlen = wbuf->offs - offs;
927 	if (rlen < 0)
928 		rlen = 0;
929 
930 	/* Copy the rest from the write-buffer */
931 	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
932 	spin_unlock(&wbuf->lock);
933 
934 	if (rlen > 0) {
935 		/* Read everything that goes before write-buffer */
936 		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
937 		if (err && err != -EBADMSG)
938 			return err;
939 	}
940 
941 	if (type != ch->node_type) {
942 		ubifs_err("bad node type (%d but expected %d)",
943 			  ch->node_type, type);
944 		goto out;
945 	}
946 
947 	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
948 	if (err) {
949 		ubifs_err("expected node type %d", type);
950 		return err;
951 	}
952 
953 	rlen = le32_to_cpu(ch->len);
954 	if (rlen != len) {
955 		ubifs_err("bad node length %d, expected %d", rlen, len);
956 		goto out;
957 	}
958 
959 	return 0;
960 
961 out:
962 	ubifs_err("bad node at LEB %d:%d", lnum, offs);
963 	dbg_dump_node(c, buf);
964 	dbg_dump_stack();
965 	return -EINVAL;
966 }
967 
968 /**
969  * ubifs_read_node - read node.
970  * @c: UBIFS file-system description object
971  * @buf: buffer to read to
972  * @type: node type
973  * @len: node length (not aligned)
974  * @lnum: logical eraseblock number
975  * @offs: offset within the logical eraseblock
976  *
977  * This function reads a node of known type and and length, checks it and
978  * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
979  * and a negative error code in case of failure.
980  */
ubifs_read_node(const struct ubifs_info * c,void * buf,int type,int len,int lnum,int offs)981 int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
982 		    int lnum, int offs)
983 {
984 	int err, l;
985 	struct ubifs_ch *ch = buf;
986 
987 	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
988 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
989 	ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
990 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
991 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
992 
993 	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
994 	if (err && err != -EBADMSG)
995 		return err;
996 
997 	if (type != ch->node_type) {
998 		ubifs_err("bad node type (%d but expected %d)",
999 			  ch->node_type, type);
1000 		goto out;
1001 	}
1002 
1003 	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
1004 	if (err) {
1005 		ubifs_err("expected node type %d", type);
1006 		return err;
1007 	}
1008 
1009 	l = le32_to_cpu(ch->len);
1010 	if (l != len) {
1011 		ubifs_err("bad node length %d, expected %d", l, len);
1012 		goto out;
1013 	}
1014 
1015 	return 0;
1016 
1017 out:
1018 	ubifs_err("bad node at LEB %d:%d, LEB mapping status %d", lnum, offs,
1019 		  ubi_is_mapped(c->ubi, lnum));
1020 	dbg_dump_node(c, buf);
1021 	dbg_dump_stack();
1022 	return -EINVAL;
1023 }
1024 
1025 /**
1026  * ubifs_wbuf_init - initialize write-buffer.
1027  * @c: UBIFS file-system description object
1028  * @wbuf: write-buffer to initialize
1029  *
1030  * This function initializes write-buffer. Returns zero in case of success
1031  * %-ENOMEM in case of failure.
1032  */
ubifs_wbuf_init(struct ubifs_info * c,struct ubifs_wbuf * wbuf)1033 int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
1034 {
1035 	size_t size;
1036 
1037 	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
1038 	if (!wbuf->buf)
1039 		return -ENOMEM;
1040 
1041 	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
1042 	wbuf->inodes = kmalloc(size, GFP_KERNEL);
1043 	if (!wbuf->inodes) {
1044 		kfree(wbuf->buf);
1045 		wbuf->buf = NULL;
1046 		return -ENOMEM;
1047 	}
1048 
1049 	wbuf->used = 0;
1050 	wbuf->lnum = wbuf->offs = -1;
1051 	/*
1052 	 * If the LEB starts at the max. write size aligned address, then
1053 	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
1054 	 * set it to something smaller so that it ends at the closest max.
1055 	 * write size boundary.
1056 	 */
1057 	size = c->max_write_size - (c->leb_start % c->max_write_size);
1058 	wbuf->avail = wbuf->size = size;
1059 	wbuf->dtype = UBI_UNKNOWN;
1060 	wbuf->sync_callback = NULL;
1061 	mutex_init(&wbuf->io_mutex);
1062 	spin_lock_init(&wbuf->lock);
1063 	wbuf->c = c;
1064 	wbuf->next_ino = 0;
1065 
1066 	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1067 	wbuf->timer.function = wbuf_timer_callback_nolock;
1068 	wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
1069 	wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
1070 	wbuf->delta *= 1000000000ULL;
1071 	ubifs_assert(wbuf->delta <= ULONG_MAX);
1072 	return 0;
1073 }
1074 
1075 /**
1076  * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
1077  * @wbuf: the write-buffer where to add
1078  * @inum: the inode number
1079  *
1080  * This function adds an inode number to the inode array of the write-buffer.
1081  */
ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf * wbuf,ino_t inum)1082 void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
1083 {
1084 	if (!wbuf->buf)
1085 		/* NOR flash or something similar */
1086 		return;
1087 
1088 	spin_lock(&wbuf->lock);
1089 	if (wbuf->used)
1090 		wbuf->inodes[wbuf->next_ino++] = inum;
1091 	spin_unlock(&wbuf->lock);
1092 }
1093 
1094 /**
1095  * wbuf_has_ino - returns if the wbuf contains data from the inode.
1096  * @wbuf: the write-buffer
1097  * @inum: the inode number
1098  *
1099  * This function returns with %1 if the write-buffer contains some data from the
1100  * given inode otherwise it returns with %0.
1101  */
wbuf_has_ino(struct ubifs_wbuf * wbuf,ino_t inum)1102 static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
1103 {
1104 	int i, ret = 0;
1105 
1106 	spin_lock(&wbuf->lock);
1107 	for (i = 0; i < wbuf->next_ino; i++)
1108 		if (inum == wbuf->inodes[i]) {
1109 			ret = 1;
1110 			break;
1111 		}
1112 	spin_unlock(&wbuf->lock);
1113 
1114 	return ret;
1115 }
1116 
1117 /**
1118  * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
1119  * @c: UBIFS file-system description object
1120  * @inode: inode to synchronize
1121  *
1122  * This function synchronizes write-buffers which contain nodes belonging to
1123  * @inode. Returns zero in case of success and a negative error code in case of
1124  * failure.
1125  */
ubifs_sync_wbufs_by_inode(struct ubifs_info * c,struct inode * inode)1126 int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
1127 {
1128 	int i, err = 0;
1129 
1130 	for (i = 0; i < c->jhead_cnt; i++) {
1131 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
1132 
1133 		if (i == GCHD)
1134 			/*
1135 			 * GC head is special, do not look at it. Even if the
1136 			 * head contains something related to this inode, it is
1137 			 * a _copy_ of corresponding on-flash node which sits
1138 			 * somewhere else.
1139 			 */
1140 			continue;
1141 
1142 		if (!wbuf_has_ino(wbuf, inode->i_ino))
1143 			continue;
1144 
1145 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
1146 		if (wbuf_has_ino(wbuf, inode->i_ino))
1147 			err = ubifs_wbuf_sync_nolock(wbuf);
1148 		mutex_unlock(&wbuf->io_mutex);
1149 
1150 		if (err) {
1151 			ubifs_ro_mode(c, err);
1152 			return err;
1153 		}
1154 	}
1155 	return 0;
1156 }
1157