1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * This file is part of UBIFS.
4  *
5  * Copyright (C) 2006-2008 Nokia Corporation.
6  * Copyright (C) 2006, 2007 University of Szeged, Hungary
7  *
8  * Authors: Artem Bityutskiy (Битюцкий Артём)
9  *          Adrian Hunter
10  *          Zoltan Sogor
11  */
12 
13 /*
14  * This file implements UBIFS I/O subsystem which provides various I/O-related
15  * helper functions (reading/writing/checking/validating nodes) and implements
16  * write-buffering support. Write buffers help to save space which otherwise
17  * would have been wasted for padding to the nearest minimal I/O unit boundary.
18  * Instead, data first goes to the write-buffer and is flushed when the
19  * buffer is full or when it is not used for some time (by timer). This is
20  * similar to the mechanism is used by JFFS2.
21  *
22  * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
23  * write size (@c->max_write_size). The latter is the maximum amount of bytes
24  * the underlying flash is able to program at a time, and writing in
25  * @c->max_write_size units should presumably be faster. Obviously,
26  * @c->min_io_size <= @c->max_write_size. Write-buffers are of
27  * @c->max_write_size bytes in size for maximum performance. However, when a
28  * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
29  * boundary) which contains data is written, not the whole write-buffer,
30  * because this is more space-efficient.
31  *
32  * This optimization adds few complications to the code. Indeed, on the one
33  * hand, we want to write in optimal @c->max_write_size bytes chunks, which
34  * also means aligning writes at the @c->max_write_size bytes offsets. On the
35  * other hand, we do not want to waste space when synchronizing the write
36  * buffer, so during synchronization we writes in smaller chunks. And this makes
37  * the next write offset to be not aligned to @c->max_write_size bytes. So the
38  * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
39  * to @c->max_write_size bytes again. We do this by temporarily shrinking
40  * write-buffer size (@wbuf->size).
41  *
42  * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
43  * mutexes defined inside these objects. Since sometimes upper-level code
44  * has to lock the write-buffer (e.g. journal space reservation code), many
45  * functions related to write-buffers have "nolock" suffix which means that the
46  * caller has to lock the write-buffer before calling this function.
47  *
48  * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
49  * aligned, UBIFS starts the next node from the aligned address, and the padded
50  * bytes may contain any rubbish. In other words, UBIFS does not put padding
51  * bytes in those small gaps. Common headers of nodes store real node lengths,
52  * not aligned lengths. Indexing nodes also store real lengths in branches.
53  *
54  * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
55  * uses padding nodes or padding bytes, if the padding node does not fit.
56  *
57  * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
58  * they are read from the flash media.
59  */
60 
61 #ifndef __UBOOT__
62 #include <linux/crc32.h>
63 #include <linux/slab.h>
64 #else
65 #include <linux/compat.h>
66 #include <linux/err.h>
67 #endif
68 #include "ubifs.h"
69 
70 /**
71  * ubifs_ro_mode - switch UBIFS to read read-only mode.
72  * @c: UBIFS file-system description object
73  * @err: error code which is the reason of switching to R/O mode
74  */
ubifs_ro_mode(struct ubifs_info * c,int err)75 void ubifs_ro_mode(struct ubifs_info *c, int err)
76 {
77 	if (!c->ro_error) {
78 		c->ro_error = 1;
79 		c->no_chk_data_crc = 0;
80 		c->vfs_sb->s_flags |= MS_RDONLY;
81 		ubifs_warn(c, "switched to read-only mode, error %d", err);
82 		dump_stack();
83 	}
84 }
85 
86 /*
87  * Below are simple wrappers over UBI I/O functions which include some
88  * additional checks and UBIFS debugging stuff. See corresponding UBI function
89  * for more information.
90  */
91 
ubifs_leb_read(const struct ubifs_info * c,int lnum,void * buf,int offs,int len,int even_ebadmsg)92 int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
93 		   int len, int even_ebadmsg)
94 {
95 	int err;
96 
97 	err = ubi_read(c->ubi, lnum, buf, offs, len);
98 	/*
99 	 * In case of %-EBADMSG print the error message only if the
100 	 * @even_ebadmsg is true.
101 	 */
102 	if (err && (err != -EBADMSG || even_ebadmsg)) {
103 		ubifs_err(c, "reading %d bytes from LEB %d:%d failed, error %d",
104 			  len, lnum, offs, err);
105 		dump_stack();
106 	}
107 	return err;
108 }
109 
ubifs_leb_write(struct ubifs_info * c,int lnum,const void * buf,int offs,int len)110 int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
111 		    int len)
112 {
113 	int err;
114 
115 	ubifs_assert(!c->ro_media && !c->ro_mount);
116 	if (c->ro_error)
117 		return -EROFS;
118 	if (!dbg_is_tst_rcvry(c))
119 		err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
120 #ifndef __UBOOT__
121 	else
122 		err = dbg_leb_write(c, lnum, buf, offs, len);
123 #endif
124 	if (err) {
125 		ubifs_err(c, "writing %d bytes to LEB %d:%d failed, error %d",
126 			  len, lnum, offs, err);
127 		ubifs_ro_mode(c, err);
128 		dump_stack();
129 	}
130 	return err;
131 }
132 
ubifs_leb_change(struct ubifs_info * c,int lnum,const void * buf,int len)133 int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
134 {
135 	int err;
136 
137 	ubifs_assert(!c->ro_media && !c->ro_mount);
138 	if (c->ro_error)
139 		return -EROFS;
140 	if (!dbg_is_tst_rcvry(c))
141 		err = ubi_leb_change(c->ubi, lnum, buf, len);
142 #ifndef __UBOOT__
143 	else
144 		err = dbg_leb_change(c, lnum, buf, len);
145 #endif
146 	if (err) {
147 		ubifs_err(c, "changing %d bytes in LEB %d failed, error %d",
148 			  len, lnum, err);
149 		ubifs_ro_mode(c, err);
150 		dump_stack();
151 	}
152 	return err;
153 }
154 
ubifs_leb_unmap(struct ubifs_info * c,int lnum)155 int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
156 {
157 	int err;
158 
159 	ubifs_assert(!c->ro_media && !c->ro_mount);
160 	if (c->ro_error)
161 		return -EROFS;
162 	if (!dbg_is_tst_rcvry(c))
163 		err = ubi_leb_unmap(c->ubi, lnum);
164 #ifndef __UBOOT__
165 	else
166 		err = dbg_leb_unmap(c, lnum);
167 #endif
168 	if (err) {
169 		ubifs_err(c, "unmap LEB %d failed, error %d", lnum, err);
170 		ubifs_ro_mode(c, err);
171 		dump_stack();
172 	}
173 	return err;
174 }
175 
ubifs_leb_map(struct ubifs_info * c,int lnum)176 int ubifs_leb_map(struct ubifs_info *c, int lnum)
177 {
178 	int err;
179 
180 	ubifs_assert(!c->ro_media && !c->ro_mount);
181 	if (c->ro_error)
182 		return -EROFS;
183 	if (!dbg_is_tst_rcvry(c))
184 		err = ubi_leb_map(c->ubi, lnum);
185 #ifndef __UBOOT__
186 	else
187 		err = dbg_leb_map(c, lnum);
188 #endif
189 	if (err) {
190 		ubifs_err(c, "mapping LEB %d failed, error %d", lnum, err);
191 		ubifs_ro_mode(c, err);
192 		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(c, "ubi_is_mapped failed for LEB %d, error %d",
204 			  lnum, err);
205 		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(c, "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(c, "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(c, "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(c, "bad node length %d", node_len);
294 out:
295 	if (!quiet) {
296 		ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
297 		ubifs_dump_node(c, buf);
298 		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(c, "sequence number overflow %llu, end of life",
360 				  sqnum);
361 			ubifs_ro_mode(c, -EINVAL);
362 		}
363 		ubifs_warn(c, "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 #ifndef __UBOOT__
434 /**
435  * wbuf_timer_callback - write-buffer timer callback function.
436  * @timer: timer data (write-buffer descriptor)
437  *
438  * This function is called when the write-buffer timer expires.
439  */
wbuf_timer_callback_nolock(struct hrtimer * timer)440 static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
441 {
442 	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
443 
444 	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
445 	wbuf->need_sync = 1;
446 	wbuf->c->need_wbuf_sync = 1;
447 	ubifs_wake_up_bgt(wbuf->c);
448 	return HRTIMER_NORESTART;
449 }
450 
451 /**
452  * new_wbuf_timer - start new write-buffer timer.
453  * @wbuf: write-buffer descriptor
454  */
new_wbuf_timer_nolock(struct ubifs_wbuf * wbuf)455 static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
456 {
457 	ubifs_assert(!hrtimer_active(&wbuf->timer));
458 
459 	if (wbuf->no_timer)
460 		return;
461 	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
462 	       dbg_jhead(wbuf->jhead),
463 	       div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
464 	       div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
465 		       USEC_PER_SEC));
466 	hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
467 			       HRTIMER_MODE_REL);
468 }
469 #endif
470 
471 /**
472  * cancel_wbuf_timer - cancel write-buffer timer.
473  * @wbuf: write-buffer descriptor
474  */
cancel_wbuf_timer_nolock(struct ubifs_wbuf * wbuf)475 static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
476 {
477 	if (wbuf->no_timer)
478 		return;
479 	wbuf->need_sync = 0;
480 #ifndef __UBOOT__
481 	hrtimer_cancel(&wbuf->timer);
482 #endif
483 }
484 
485 /**
486  * ubifs_wbuf_sync_nolock - synchronize write-buffer.
487  * @wbuf: write-buffer to synchronize
488  *
489  * This function synchronizes write-buffer @buf and returns zero in case of
490  * success or a negative error code in case of failure.
491  *
492  * Note, although write-buffers are of @c->max_write_size, this function does
493  * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
494  * if the write-buffer is only partially filled with data, only the used part
495  * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
496  * This way we waste less space.
497  */
ubifs_wbuf_sync_nolock(struct ubifs_wbuf * wbuf)498 int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
499 {
500 	struct ubifs_info *c = wbuf->c;
501 	int err, dirt, sync_len;
502 
503 	cancel_wbuf_timer_nolock(wbuf);
504 	if (!wbuf->used || wbuf->lnum == -1)
505 		/* Write-buffer is empty or not seeked */
506 		return 0;
507 
508 	dbg_io("LEB %d:%d, %d bytes, jhead %s",
509 	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
510 	ubifs_assert(!(wbuf->avail & 7));
511 	ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
512 	ubifs_assert(wbuf->size >= c->min_io_size);
513 	ubifs_assert(wbuf->size <= c->max_write_size);
514 	ubifs_assert(wbuf->size % c->min_io_size == 0);
515 	ubifs_assert(!c->ro_media && !c->ro_mount);
516 	if (c->leb_size - wbuf->offs >= c->max_write_size)
517 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
518 
519 	if (c->ro_error)
520 		return -EROFS;
521 
522 	/*
523 	 * Do not write whole write buffer but write only the minimum necessary
524 	 * amount of min. I/O units.
525 	 */
526 	sync_len = ALIGN(wbuf->used, c->min_io_size);
527 	dirt = sync_len - wbuf->used;
528 	if (dirt)
529 		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
530 	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
531 	if (err)
532 		return err;
533 
534 	spin_lock(&wbuf->lock);
535 	wbuf->offs += sync_len;
536 	/*
537 	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
538 	 * But our goal is to optimize writes and make sure we write in
539 	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
540 	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
541 	 * sure that @wbuf->offs + @wbuf->size is aligned to
542 	 * @c->max_write_size. This way we make sure that after next
543 	 * write-buffer flush we are again at the optimal offset (aligned to
544 	 * @c->max_write_size).
545 	 */
546 	if (c->leb_size - wbuf->offs < c->max_write_size)
547 		wbuf->size = c->leb_size - wbuf->offs;
548 	else if (wbuf->offs & (c->max_write_size - 1))
549 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
550 	else
551 		wbuf->size = c->max_write_size;
552 	wbuf->avail = wbuf->size;
553 	wbuf->used = 0;
554 	wbuf->next_ino = 0;
555 	spin_unlock(&wbuf->lock);
556 
557 	if (wbuf->sync_callback)
558 		err = wbuf->sync_callback(c, wbuf->lnum,
559 					  c->leb_size - wbuf->offs, dirt);
560 	return err;
561 }
562 
563 /**
564  * ubifs_wbuf_seek_nolock - seek write-buffer.
565  * @wbuf: write-buffer
566  * @lnum: logical eraseblock number to seek to
567  * @offs: logical eraseblock offset to seek to
568  *
569  * This function targets the write-buffer to logical eraseblock @lnum:@offs.
570  * The write-buffer has to be empty. Returns zero in case of success and a
571  * negative error code in case of failure.
572  */
ubifs_wbuf_seek_nolock(struct ubifs_wbuf * wbuf,int lnum,int offs)573 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
574 {
575 	const struct ubifs_info *c = wbuf->c;
576 
577 	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
578 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
579 	ubifs_assert(offs >= 0 && offs <= c->leb_size);
580 	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
581 	ubifs_assert(lnum != wbuf->lnum);
582 	ubifs_assert(wbuf->used == 0);
583 
584 	spin_lock(&wbuf->lock);
585 	wbuf->lnum = lnum;
586 	wbuf->offs = offs;
587 	if (c->leb_size - wbuf->offs < c->max_write_size)
588 		wbuf->size = c->leb_size - wbuf->offs;
589 	else if (wbuf->offs & (c->max_write_size - 1))
590 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
591 	else
592 		wbuf->size = c->max_write_size;
593 	wbuf->avail = wbuf->size;
594 	wbuf->used = 0;
595 	spin_unlock(&wbuf->lock);
596 
597 	return 0;
598 }
599 
600 #ifndef __UBOOT__
601 /**
602  * ubifs_bg_wbufs_sync - synchronize write-buffers.
603  * @c: UBIFS file-system description object
604  *
605  * This function is called by background thread to synchronize write-buffers.
606  * Returns zero in case of success and a negative error code in case of
607  * failure.
608  */
ubifs_bg_wbufs_sync(struct ubifs_info * c)609 int ubifs_bg_wbufs_sync(struct ubifs_info *c)
610 {
611 	int err, i;
612 
613 	ubifs_assert(!c->ro_media && !c->ro_mount);
614 	if (!c->need_wbuf_sync)
615 		return 0;
616 	c->need_wbuf_sync = 0;
617 
618 	if (c->ro_error) {
619 		err = -EROFS;
620 		goto out_timers;
621 	}
622 
623 	dbg_io("synchronize");
624 	for (i = 0; i < c->jhead_cnt; i++) {
625 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
626 
627 		cond_resched();
628 
629 		/*
630 		 * If the mutex is locked then wbuf is being changed, so
631 		 * synchronization is not necessary.
632 		 */
633 		if (mutex_is_locked(&wbuf->io_mutex))
634 			continue;
635 
636 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
637 		if (!wbuf->need_sync) {
638 			mutex_unlock(&wbuf->io_mutex);
639 			continue;
640 		}
641 
642 		err = ubifs_wbuf_sync_nolock(wbuf);
643 		mutex_unlock(&wbuf->io_mutex);
644 		if (err) {
645 			ubifs_err(c, "cannot sync write-buffer, error %d", err);
646 			ubifs_ro_mode(c, err);
647 			goto out_timers;
648 		}
649 	}
650 
651 	return 0;
652 
653 out_timers:
654 	/* Cancel all timers to prevent repeated errors */
655 	for (i = 0; i < c->jhead_cnt; i++) {
656 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
657 
658 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
659 		cancel_wbuf_timer_nolock(wbuf);
660 		mutex_unlock(&wbuf->io_mutex);
661 	}
662 	return err;
663 }
664 
665 /**
666  * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
667  * @wbuf: write-buffer
668  * @buf: node to write
669  * @len: node length
670  *
671  * This function writes data to flash via write-buffer @wbuf. This means that
672  * the last piece of the node won't reach the flash media immediately if it
673  * does not take whole max. write unit (@c->max_write_size). Instead, the node
674  * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
675  * because more data are appended to the write-buffer).
676  *
677  * This function returns zero in case of success and a negative error code in
678  * case of failure. If the node cannot be written because there is no more
679  * space in this logical eraseblock, %-ENOSPC is returned.
680  */
ubifs_wbuf_write_nolock(struct ubifs_wbuf * wbuf,void * buf,int len)681 int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
682 {
683 	struct ubifs_info *c = wbuf->c;
684 	int err, written, n, aligned_len = ALIGN(len, 8);
685 
686 	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
687 	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
688 	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
689 	ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
690 	ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
691 	ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
692 	ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
693 	ubifs_assert(wbuf->size >= c->min_io_size);
694 	ubifs_assert(wbuf->size <= c->max_write_size);
695 	ubifs_assert(wbuf->size % c->min_io_size == 0);
696 	ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
697 	ubifs_assert(!c->ro_media && !c->ro_mount);
698 	ubifs_assert(!c->space_fixup);
699 	if (c->leb_size - wbuf->offs >= c->max_write_size)
700 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
701 
702 	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
703 		err = -ENOSPC;
704 		goto out;
705 	}
706 
707 	cancel_wbuf_timer_nolock(wbuf);
708 
709 	if (c->ro_error)
710 		return -EROFS;
711 
712 	if (aligned_len <= wbuf->avail) {
713 		/*
714 		 * The node is not very large and fits entirely within
715 		 * write-buffer.
716 		 */
717 		memcpy(wbuf->buf + wbuf->used, buf, len);
718 
719 		if (aligned_len == wbuf->avail) {
720 			dbg_io("flush jhead %s wbuf to LEB %d:%d",
721 			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
722 			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
723 					      wbuf->offs, wbuf->size);
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);
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);
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);
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(c, "cannot write %d bytes to LEB %d:%d, error %d",
843 		  len, wbuf->lnum, wbuf->offs, err);
844 	ubifs_dump_node(c, buf);
845 	dump_stack();
846 	ubifs_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  *
858  * This function automatically fills node magic number, assigns sequence
859  * number, and calculates node CRC checksum. The length of the @buf buffer has
860  * to be aligned to the minimal I/O unit size. This function automatically
861  * appends padding node and padding bytes if needed. Returns zero in case of
862  * success and a negative error code in case of failure.
863  */
ubifs_write_node(struct ubifs_info * c,void * buf,int len,int lnum,int offs)864 int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
865 		     int offs)
866 {
867 	int err, buf_len = ALIGN(len, c->min_io_size);
868 
869 	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
870 	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
871 	       buf_len);
872 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
873 	ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
874 	ubifs_assert(!c->ro_media && !c->ro_mount);
875 	ubifs_assert(!c->space_fixup);
876 
877 	if (c->ro_error)
878 		return -EROFS;
879 
880 	ubifs_prepare_node(c, buf, len, 1);
881 	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
882 	if (err)
883 		ubifs_dump_node(c, buf);
884 
885 	return err;
886 }
887 #endif
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(c, "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(c, "expected node type %d", type);
950 		return err;
951 	}
952 
953 	rlen = le32_to_cpu(ch->len);
954 	if (rlen != len) {
955 		ubifs_err(c, "bad node length %d, expected %d", rlen, len);
956 		goto out;
957 	}
958 
959 	return 0;
960 
961 out:
962 	ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
963 	ubifs_dump_node(c, buf);
964 	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_errc(c, "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_errc(c, "expected node type %d", type);
1006 		return err;
1007 	}
1008 
1009 	l = le32_to_cpu(ch->len);
1010 	if (l != len) {
1011 		ubifs_errc(c, "bad node length %d, expected %d", l, len);
1012 		goto out;
1013 	}
1014 
1015 	return 0;
1016 
1017 out:
1018 	ubifs_errc(c, "bad node at LEB %d:%d, LEB mapping status %d", lnum,
1019 		   offs, ubi_is_mapped(c->ubi, lnum));
1020 	if (!c->probing) {
1021 		ubifs_dump_node(c, buf);
1022 		dump_stack();
1023 	}
1024 	return -EINVAL;
1025 }
1026 
1027 /**
1028  * ubifs_wbuf_init - initialize write-buffer.
1029  * @c: UBIFS file-system description object
1030  * @wbuf: write-buffer to initialize
1031  *
1032  * This function initializes write-buffer. Returns zero in case of success
1033  * %-ENOMEM in case of failure.
1034  */
ubifs_wbuf_init(struct ubifs_info * c,struct ubifs_wbuf * wbuf)1035 int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
1036 {
1037 	size_t size;
1038 
1039 	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
1040 	if (!wbuf->buf)
1041 		return -ENOMEM;
1042 
1043 	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
1044 	wbuf->inodes = kmalloc(size, GFP_KERNEL);
1045 	if (!wbuf->inodes) {
1046 		kfree(wbuf->buf);
1047 		wbuf->buf = NULL;
1048 		return -ENOMEM;
1049 	}
1050 
1051 	wbuf->used = 0;
1052 	wbuf->lnum = wbuf->offs = -1;
1053 	/*
1054 	 * If the LEB starts at the max. write size aligned address, then
1055 	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
1056 	 * set it to something smaller so that it ends at the closest max.
1057 	 * write size boundary.
1058 	 */
1059 	size = c->max_write_size - (c->leb_start % c->max_write_size);
1060 	wbuf->avail = wbuf->size = size;
1061 	wbuf->sync_callback = NULL;
1062 	mutex_init(&wbuf->io_mutex);
1063 	spin_lock_init(&wbuf->lock);
1064 	wbuf->c = c;
1065 	wbuf->next_ino = 0;
1066 
1067 #ifndef __UBOOT__
1068 	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1069 	wbuf->timer.function = wbuf_timer_callback_nolock;
1070 	wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
1071 	wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
1072 	wbuf->delta *= 1000000000ULL;
1073 	ubifs_assert(wbuf->delta <= ULONG_MAX);
1074 #endif
1075 	return 0;
1076 }
1077 
1078 /**
1079  * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
1080  * @wbuf: the write-buffer where to add
1081  * @inum: the inode number
1082  *
1083  * This function adds an inode number to the inode array of the write-buffer.
1084  */
ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf * wbuf,ino_t inum)1085 void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
1086 {
1087 	if (!wbuf->buf)
1088 		/* NOR flash or something similar */
1089 		return;
1090 
1091 	spin_lock(&wbuf->lock);
1092 	if (wbuf->used)
1093 		wbuf->inodes[wbuf->next_ino++] = inum;
1094 	spin_unlock(&wbuf->lock);
1095 }
1096 
1097 /**
1098  * wbuf_has_ino - returns if the wbuf contains data from the inode.
1099  * @wbuf: the write-buffer
1100  * @inum: the inode number
1101  *
1102  * This function returns with %1 if the write-buffer contains some data from the
1103  * given inode otherwise it returns with %0.
1104  */
wbuf_has_ino(struct ubifs_wbuf * wbuf,ino_t inum)1105 static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
1106 {
1107 	int i, ret = 0;
1108 
1109 	spin_lock(&wbuf->lock);
1110 	for (i = 0; i < wbuf->next_ino; i++)
1111 		if (inum == wbuf->inodes[i]) {
1112 			ret = 1;
1113 			break;
1114 		}
1115 	spin_unlock(&wbuf->lock);
1116 
1117 	return ret;
1118 }
1119 
1120 /**
1121  * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
1122  * @c: UBIFS file-system description object
1123  * @inode: inode to synchronize
1124  *
1125  * This function synchronizes write-buffers which contain nodes belonging to
1126  * @inode. Returns zero in case of success and a negative error code in case of
1127  * failure.
1128  */
ubifs_sync_wbufs_by_inode(struct ubifs_info * c,struct inode * inode)1129 int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
1130 {
1131 	int i, err = 0;
1132 
1133 	for (i = 0; i < c->jhead_cnt; i++) {
1134 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
1135 
1136 		if (i == GCHD)
1137 			/*
1138 			 * GC head is special, do not look at it. Even if the
1139 			 * head contains something related to this inode, it is
1140 			 * a _copy_ of corresponding on-flash node which sits
1141 			 * somewhere else.
1142 			 */
1143 			continue;
1144 
1145 		if (!wbuf_has_ino(wbuf, inode->i_ino))
1146 			continue;
1147 
1148 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
1149 		if (wbuf_has_ino(wbuf, inode->i_ino))
1150 			err = ubifs_wbuf_sync_nolock(wbuf);
1151 		mutex_unlock(&wbuf->io_mutex);
1152 
1153 		if (err) {
1154 			ubifs_ro_mode(c, err);
1155 			return err;
1156 		}
1157 	}
1158 	return 0;
1159 }
1160