1 // SPDX-License-Identifier: GPL-2.0-only
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 #include <linux/crc32.h>
62 #include <linux/slab.h>
63 #include "ubifs.h"
64 
65 /**
66  * ubifs_ro_mode - switch UBIFS to read read-only mode.
67  * @c: UBIFS file-system description object
68  * @err: error code which is the reason of switching to R/O mode
69  */
ubifs_ro_mode(struct ubifs_info * c,int err)70 void ubifs_ro_mode(struct ubifs_info *c, int err)
71 {
72 	if (!c->ro_error) {
73 		c->ro_error = 1;
74 		c->no_chk_data_crc = 0;
75 		c->vfs_sb->s_flags |= SB_RDONLY;
76 		ubifs_warn(c, "switched to read-only mode, error %d", err);
77 		dump_stack();
78 	}
79 }
80 
81 /*
82  * Below are simple wrappers over UBI I/O functions which include some
83  * additional checks and UBIFS debugging stuff. See corresponding UBI function
84  * for more information.
85  */
86 
ubifs_leb_read(const struct ubifs_info * c,int lnum,void * buf,int offs,int len,int even_ebadmsg)87 int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
88 		   int len, int even_ebadmsg)
89 {
90 	int err;
91 
92 	err = ubi_read(c->ubi, lnum, buf, offs, len);
93 	/*
94 	 * In case of %-EBADMSG print the error message only if the
95 	 * @even_ebadmsg is true.
96 	 */
97 	if (err && (err != -EBADMSG || even_ebadmsg)) {
98 		ubifs_err(c, "reading %d bytes from LEB %d:%d failed, error %d",
99 			  len, lnum, offs, err);
100 		dump_stack();
101 	}
102 	return err;
103 }
104 
ubifs_leb_write(struct ubifs_info * c,int lnum,const void * buf,int offs,int len)105 int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
106 		    int len)
107 {
108 	int err;
109 
110 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
111 	if (c->ro_error)
112 		return -EROFS;
113 	if (!dbg_is_tst_rcvry(c))
114 		err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
115 	else
116 		err = dbg_leb_write(c, lnum, buf, offs, len);
117 	if (err) {
118 		ubifs_err(c, "writing %d bytes to LEB %d:%d failed, error %d",
119 			  len, lnum, offs, err);
120 		ubifs_ro_mode(c, err);
121 		dump_stack();
122 	}
123 	return err;
124 }
125 
ubifs_leb_change(struct ubifs_info * c,int lnum,const void * buf,int len)126 int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
127 {
128 	int err;
129 
130 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
131 	if (c->ro_error)
132 		return -EROFS;
133 	if (!dbg_is_tst_rcvry(c))
134 		err = ubi_leb_change(c->ubi, lnum, buf, len);
135 	else
136 		err = dbg_leb_change(c, lnum, buf, len);
137 	if (err) {
138 		ubifs_err(c, "changing %d bytes in LEB %d failed, error %d",
139 			  len, lnum, err);
140 		ubifs_ro_mode(c, err);
141 		dump_stack();
142 	}
143 	return err;
144 }
145 
ubifs_leb_unmap(struct ubifs_info * c,int lnum)146 int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
147 {
148 	int err;
149 
150 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
151 	if (c->ro_error)
152 		return -EROFS;
153 	if (!dbg_is_tst_rcvry(c))
154 		err = ubi_leb_unmap(c->ubi, lnum);
155 	else
156 		err = dbg_leb_unmap(c, lnum);
157 	if (err) {
158 		ubifs_err(c, "unmap LEB %d failed, error %d", lnum, err);
159 		ubifs_ro_mode(c, err);
160 		dump_stack();
161 	}
162 	return err;
163 }
164 
ubifs_leb_map(struct ubifs_info * c,int lnum)165 int ubifs_leb_map(struct ubifs_info *c, int lnum)
166 {
167 	int err;
168 
169 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
170 	if (c->ro_error)
171 		return -EROFS;
172 	if (!dbg_is_tst_rcvry(c))
173 		err = ubi_leb_map(c->ubi, lnum);
174 	else
175 		err = dbg_leb_map(c, lnum);
176 	if (err) {
177 		ubifs_err(c, "mapping LEB %d failed, error %d", lnum, err);
178 		ubifs_ro_mode(c, err);
179 		dump_stack();
180 	}
181 	return err;
182 }
183 
ubifs_is_mapped(const struct ubifs_info * c,int lnum)184 int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
185 {
186 	int err;
187 
188 	err = ubi_is_mapped(c->ubi, lnum);
189 	if (err < 0) {
190 		ubifs_err(c, "ubi_is_mapped failed for LEB %d, error %d",
191 			  lnum, err);
192 		dump_stack();
193 	}
194 	return err;
195 }
196 
record_magic_error(struct ubifs_stats_info * stats)197 static void record_magic_error(struct ubifs_stats_info *stats)
198 {
199 	if (stats)
200 		stats->magic_errors++;
201 }
202 
record_node_error(struct ubifs_stats_info * stats)203 static void record_node_error(struct ubifs_stats_info *stats)
204 {
205 	if (stats)
206 		stats->node_errors++;
207 }
208 
record_crc_error(struct ubifs_stats_info * stats)209 static void record_crc_error(struct ubifs_stats_info *stats)
210 {
211 	if (stats)
212 		stats->crc_errors++;
213 }
214 
215 /**
216  * ubifs_check_node - check node.
217  * @c: UBIFS file-system description object
218  * @buf: node to check
219  * @len: node length
220  * @lnum: logical eraseblock number
221  * @offs: offset within the logical eraseblock
222  * @quiet: print no messages
223  * @must_chk_crc: indicates whether to always check the CRC
224  *
225  * This function checks node magic number and CRC checksum. This function also
226  * validates node length to prevent UBIFS from becoming crazy when an attacker
227  * feeds it a file-system image with incorrect nodes. For example, too large
228  * node length in the common header could cause UBIFS to read memory outside of
229  * allocated buffer when checking the CRC checksum.
230  *
231  * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
232  * true, which is controlled by corresponding UBIFS mount option. However, if
233  * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
234  * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
235  * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
236  * is checked. This is because during mounting or re-mounting from R/O mode to
237  * R/W mode we may read journal nodes (when replying the journal or doing the
238  * recovery) and the journal nodes may potentially be corrupted, so checking is
239  * required.
240  *
241  * This function returns zero in case of success and %-EUCLEAN in case of bad
242  * CRC or magic.
243  */
ubifs_check_node(const struct ubifs_info * c,const void * buf,int len,int lnum,int offs,int quiet,int must_chk_crc)244 int ubifs_check_node(const struct ubifs_info *c, const void *buf, int len,
245 		     int lnum, int offs, int quiet, int must_chk_crc)
246 {
247 	int err = -EINVAL, type, node_len;
248 	uint32_t crc, node_crc, magic;
249 	const struct ubifs_ch *ch = buf;
250 
251 	ubifs_assert(c, lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
252 	ubifs_assert(c, !(offs & 7) && offs < c->leb_size);
253 
254 	magic = le32_to_cpu(ch->magic);
255 	if (magic != UBIFS_NODE_MAGIC) {
256 		if (!quiet)
257 			ubifs_err(c, "bad magic %#08x, expected %#08x",
258 				  magic, UBIFS_NODE_MAGIC);
259 		record_magic_error(c->stats);
260 		err = -EUCLEAN;
261 		goto out;
262 	}
263 
264 	type = ch->node_type;
265 	if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
266 		if (!quiet)
267 			ubifs_err(c, "bad node type %d", type);
268 		record_node_error(c->stats);
269 		goto out;
270 	}
271 
272 	node_len = le32_to_cpu(ch->len);
273 	if (node_len + offs > c->leb_size)
274 		goto out_len;
275 
276 	if (c->ranges[type].max_len == 0) {
277 		if (node_len != c->ranges[type].len)
278 			goto out_len;
279 	} else if (node_len < c->ranges[type].min_len ||
280 		   node_len > c->ranges[type].max_len)
281 		goto out_len;
282 
283 	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
284 	    !c->remounting_rw && c->no_chk_data_crc)
285 		return 0;
286 
287 	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
288 	node_crc = le32_to_cpu(ch->crc);
289 	if (crc != node_crc) {
290 		if (!quiet)
291 			ubifs_err(c, "bad CRC: calculated %#08x, read %#08x",
292 				  crc, node_crc);
293 		record_crc_error(c->stats);
294 		err = -EUCLEAN;
295 		goto out;
296 	}
297 
298 	return 0;
299 
300 out_len:
301 	if (!quiet)
302 		ubifs_err(c, "bad node length %d", node_len);
303 out:
304 	if (!quiet) {
305 		ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
306 		ubifs_dump_node(c, buf, len);
307 		dump_stack();
308 	}
309 	return err;
310 }
311 
312 /**
313  * ubifs_pad - pad flash space.
314  * @c: UBIFS file-system description object
315  * @buf: buffer to put padding to
316  * @pad: how many bytes to pad
317  *
318  * The flash media obliges us to write only in chunks of %c->min_io_size and
319  * when we have to write less data we add padding node to the write-buffer and
320  * pad it to the next minimal I/O unit's boundary. Padding nodes help when the
321  * media is being scanned. If the amount of wasted space is not enough to fit a
322  * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
323  * pattern (%UBIFS_PADDING_BYTE).
324  *
325  * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
326  * used.
327  */
ubifs_pad(const struct ubifs_info * c,void * buf,int pad)328 void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
329 {
330 	uint32_t crc;
331 
332 	ubifs_assert(c, pad >= 0);
333 
334 	if (pad >= UBIFS_PAD_NODE_SZ) {
335 		struct ubifs_ch *ch = buf;
336 		struct ubifs_pad_node *pad_node = buf;
337 
338 		ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
339 		ch->node_type = UBIFS_PAD_NODE;
340 		ch->group_type = UBIFS_NO_NODE_GROUP;
341 		ch->padding[0] = ch->padding[1] = 0;
342 		ch->sqnum = 0;
343 		ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
344 		pad -= UBIFS_PAD_NODE_SZ;
345 		pad_node->pad_len = cpu_to_le32(pad);
346 		crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
347 		ch->crc = cpu_to_le32(crc);
348 		memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
349 	} else if (pad > 0)
350 		/* Too little space, padding node won't fit */
351 		memset(buf, UBIFS_PADDING_BYTE, pad);
352 }
353 
354 /**
355  * next_sqnum - get next sequence number.
356  * @c: UBIFS file-system description object
357  */
next_sqnum(struct ubifs_info * c)358 static unsigned long long next_sqnum(struct ubifs_info *c)
359 {
360 	unsigned long long sqnum;
361 
362 	spin_lock(&c->cnt_lock);
363 	sqnum = ++c->max_sqnum;
364 	spin_unlock(&c->cnt_lock);
365 
366 	if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
367 		if (sqnum >= SQNUM_WATERMARK) {
368 			ubifs_err(c, "sequence number overflow %llu, end of life",
369 				  sqnum);
370 			ubifs_ro_mode(c, -EINVAL);
371 		}
372 		ubifs_warn(c, "running out of sequence numbers, end of life soon");
373 	}
374 
375 	return sqnum;
376 }
377 
ubifs_init_node(struct ubifs_info * c,void * node,int len,int pad)378 void ubifs_init_node(struct ubifs_info *c, void *node, int len, int pad)
379 {
380 	struct ubifs_ch *ch = node;
381 	unsigned long long sqnum = next_sqnum(c);
382 
383 	ubifs_assert(c, len >= UBIFS_CH_SZ);
384 
385 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
386 	ch->len = cpu_to_le32(len);
387 	ch->group_type = UBIFS_NO_NODE_GROUP;
388 	ch->sqnum = cpu_to_le64(sqnum);
389 	ch->padding[0] = ch->padding[1] = 0;
390 
391 	if (pad) {
392 		len = ALIGN(len, 8);
393 		pad = ALIGN(len, c->min_io_size) - len;
394 		ubifs_pad(c, node + len, pad);
395 	}
396 }
397 
ubifs_crc_node(struct ubifs_info * c,void * node,int len)398 void ubifs_crc_node(struct ubifs_info *c, void *node, int len)
399 {
400 	struct ubifs_ch *ch = node;
401 	uint32_t crc;
402 
403 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
404 	ch->crc = cpu_to_le32(crc);
405 }
406 
407 /**
408  * ubifs_prepare_node_hmac - prepare node to be written to flash.
409  * @c: UBIFS file-system description object
410  * @node: the node to pad
411  * @len: node length
412  * @hmac_offs: offset of the HMAC in the node
413  * @pad: if the buffer has to be padded
414  *
415  * This function prepares node at @node to be written to the media - it
416  * calculates node CRC, fills the common header, and adds proper padding up to
417  * the next minimum I/O unit if @pad is not zero. if @hmac_offs is positive then
418  * a HMAC is inserted into the node at the given offset.
419  *
420  * This function returns 0 for success or a negative error code otherwise.
421  */
ubifs_prepare_node_hmac(struct ubifs_info * c,void * node,int len,int hmac_offs,int pad)422 int ubifs_prepare_node_hmac(struct ubifs_info *c, void *node, int len,
423 			    int hmac_offs, int pad)
424 {
425 	int err;
426 
427 	ubifs_init_node(c, node, len, pad);
428 
429 	if (hmac_offs > 0) {
430 		err = ubifs_node_insert_hmac(c, node, len, hmac_offs);
431 		if (err)
432 			return err;
433 	}
434 
435 	ubifs_crc_node(c, node, len);
436 
437 	return 0;
438 }
439 
440 /**
441  * ubifs_prepare_node - prepare node to be written to flash.
442  * @c: UBIFS file-system description object
443  * @node: the node to pad
444  * @len: node length
445  * @pad: if the buffer has to be padded
446  *
447  * This function prepares node at @node to be written to the media - it
448  * calculates node CRC, fills the common header, and adds proper padding up to
449  * the next minimum I/O unit if @pad is not zero.
450  */
ubifs_prepare_node(struct ubifs_info * c,void * node,int len,int pad)451 void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
452 {
453 	/*
454 	 * Deliberately ignore return value since this function can only fail
455 	 * when a hmac offset is given.
456 	 */
457 	ubifs_prepare_node_hmac(c, node, len, 0, pad);
458 }
459 
460 /**
461  * ubifs_prep_grp_node - prepare node of a group to be written to flash.
462  * @c: UBIFS file-system description object
463  * @node: the node to pad
464  * @len: node length
465  * @last: indicates the last node of the group
466  *
467  * This function prepares node at @node to be written to the media - it
468  * calculates node CRC and fills the common header.
469  */
ubifs_prep_grp_node(struct ubifs_info * c,void * node,int len,int last)470 void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
471 {
472 	uint32_t crc;
473 	struct ubifs_ch *ch = node;
474 	unsigned long long sqnum = next_sqnum(c);
475 
476 	ubifs_assert(c, len >= UBIFS_CH_SZ);
477 
478 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
479 	ch->len = cpu_to_le32(len);
480 	if (last)
481 		ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
482 	else
483 		ch->group_type = UBIFS_IN_NODE_GROUP;
484 	ch->sqnum = cpu_to_le64(sqnum);
485 	ch->padding[0] = ch->padding[1] = 0;
486 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
487 	ch->crc = cpu_to_le32(crc);
488 }
489 
490 /**
491  * wbuf_timer_callback_nolock - write-buffer timer callback function.
492  * @timer: timer data (write-buffer descriptor)
493  *
494  * This function is called when the write-buffer timer expires.
495  */
wbuf_timer_callback_nolock(struct hrtimer * timer)496 static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
497 {
498 	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
499 
500 	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
501 	wbuf->need_sync = 1;
502 	wbuf->c->need_wbuf_sync = 1;
503 	ubifs_wake_up_bgt(wbuf->c);
504 	return HRTIMER_NORESTART;
505 }
506 
507 /**
508  * new_wbuf_timer_nolock - start new write-buffer timer.
509  * @c: UBIFS file-system description object
510  * @wbuf: write-buffer descriptor
511  */
new_wbuf_timer_nolock(struct ubifs_info * c,struct ubifs_wbuf * wbuf)512 static void new_wbuf_timer_nolock(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
513 {
514 	ktime_t softlimit = ms_to_ktime(dirty_writeback_interval * 10);
515 	unsigned long long delta = dirty_writeback_interval;
516 
517 	/* centi to milli, milli to nano, then 10% */
518 	delta *= 10ULL * NSEC_PER_MSEC / 10ULL;
519 
520 	ubifs_assert(c, !hrtimer_active(&wbuf->timer));
521 	ubifs_assert(c, delta <= ULONG_MAX);
522 
523 	if (wbuf->no_timer)
524 		return;
525 	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
526 	       dbg_jhead(wbuf->jhead),
527 	       div_u64(ktime_to_ns(softlimit), USEC_PER_SEC),
528 	       div_u64(ktime_to_ns(softlimit) + delta, USEC_PER_SEC));
529 	hrtimer_start_range_ns(&wbuf->timer, softlimit, delta,
530 			       HRTIMER_MODE_REL);
531 }
532 
533 /**
534  * cancel_wbuf_timer_nolock - cancel write-buffer timer.
535  * @wbuf: write-buffer descriptor
536  */
cancel_wbuf_timer_nolock(struct ubifs_wbuf * wbuf)537 static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
538 {
539 	if (wbuf->no_timer)
540 		return;
541 	wbuf->need_sync = 0;
542 	hrtimer_cancel(&wbuf->timer);
543 }
544 
545 /**
546  * ubifs_wbuf_sync_nolock - synchronize write-buffer.
547  * @wbuf: write-buffer to synchronize
548  *
549  * This function synchronizes write-buffer @buf and returns zero in case of
550  * success or a negative error code in case of failure.
551  *
552  * Note, although write-buffers are of @c->max_write_size, this function does
553  * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
554  * if the write-buffer is only partially filled with data, only the used part
555  * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
556  * This way we waste less space.
557  */
ubifs_wbuf_sync_nolock(struct ubifs_wbuf * wbuf)558 int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
559 {
560 	struct ubifs_info *c = wbuf->c;
561 	int err, dirt, sync_len;
562 
563 	cancel_wbuf_timer_nolock(wbuf);
564 	if (!wbuf->used || wbuf->lnum == -1)
565 		/* Write-buffer is empty or not seeked */
566 		return 0;
567 
568 	dbg_io("LEB %d:%d, %d bytes, jhead %s",
569 	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
570 	ubifs_assert(c, !(wbuf->avail & 7));
571 	ubifs_assert(c, wbuf->offs + wbuf->size <= c->leb_size);
572 	ubifs_assert(c, wbuf->size >= c->min_io_size);
573 	ubifs_assert(c, wbuf->size <= c->max_write_size);
574 	ubifs_assert(c, wbuf->size % c->min_io_size == 0);
575 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
576 	if (c->leb_size - wbuf->offs >= c->max_write_size)
577 		ubifs_assert(c, !((wbuf->offs + wbuf->size) % c->max_write_size));
578 
579 	if (c->ro_error)
580 		return -EROFS;
581 
582 	/*
583 	 * Do not write whole write buffer but write only the minimum necessary
584 	 * amount of min. I/O units.
585 	 */
586 	sync_len = ALIGN(wbuf->used, c->min_io_size);
587 	dirt = sync_len - wbuf->used;
588 	if (dirt)
589 		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
590 	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
591 	if (err)
592 		return err;
593 
594 	spin_lock(&wbuf->lock);
595 	wbuf->offs += sync_len;
596 	/*
597 	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
598 	 * But our goal is to optimize writes and make sure we write in
599 	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
600 	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
601 	 * sure that @wbuf->offs + @wbuf->size is aligned to
602 	 * @c->max_write_size. This way we make sure that after next
603 	 * write-buffer flush we are again at the optimal offset (aligned to
604 	 * @c->max_write_size).
605 	 */
606 	if (c->leb_size - wbuf->offs < c->max_write_size)
607 		wbuf->size = c->leb_size - wbuf->offs;
608 	else if (wbuf->offs & (c->max_write_size - 1))
609 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
610 	else
611 		wbuf->size = c->max_write_size;
612 	wbuf->avail = wbuf->size;
613 	wbuf->used = 0;
614 	wbuf->next_ino = 0;
615 	spin_unlock(&wbuf->lock);
616 
617 	if (wbuf->sync_callback)
618 		err = wbuf->sync_callback(c, wbuf->lnum,
619 					  c->leb_size - wbuf->offs, dirt);
620 	return err;
621 }
622 
623 /**
624  * ubifs_wbuf_seek_nolock - seek write-buffer.
625  * @wbuf: write-buffer
626  * @lnum: logical eraseblock number to seek to
627  * @offs: logical eraseblock offset to seek to
628  *
629  * This function targets the write-buffer to logical eraseblock @lnum:@offs.
630  * The write-buffer has to be empty. Returns zero in case of success and a
631  * negative error code in case of failure.
632  */
ubifs_wbuf_seek_nolock(struct ubifs_wbuf * wbuf,int lnum,int offs)633 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
634 {
635 	const struct ubifs_info *c = wbuf->c;
636 
637 	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
638 	ubifs_assert(c, lnum >= 0 && lnum < c->leb_cnt);
639 	ubifs_assert(c, offs >= 0 && offs <= c->leb_size);
640 	ubifs_assert(c, offs % c->min_io_size == 0 && !(offs & 7));
641 	ubifs_assert(c, lnum != wbuf->lnum);
642 	ubifs_assert(c, wbuf->used == 0);
643 
644 	spin_lock(&wbuf->lock);
645 	wbuf->lnum = lnum;
646 	wbuf->offs = offs;
647 	if (c->leb_size - wbuf->offs < c->max_write_size)
648 		wbuf->size = c->leb_size - wbuf->offs;
649 	else if (wbuf->offs & (c->max_write_size - 1))
650 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
651 	else
652 		wbuf->size = c->max_write_size;
653 	wbuf->avail = wbuf->size;
654 	wbuf->used = 0;
655 	spin_unlock(&wbuf->lock);
656 
657 	return 0;
658 }
659 
660 /**
661  * ubifs_bg_wbufs_sync - synchronize write-buffers.
662  * @c: UBIFS file-system description object
663  *
664  * This function is called by background thread to synchronize write-buffers.
665  * Returns zero in case of success and a negative error code in case of
666  * failure.
667  */
ubifs_bg_wbufs_sync(struct ubifs_info * c)668 int ubifs_bg_wbufs_sync(struct ubifs_info *c)
669 {
670 	int err, i;
671 
672 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
673 	if (!c->need_wbuf_sync)
674 		return 0;
675 	c->need_wbuf_sync = 0;
676 
677 	if (c->ro_error) {
678 		err = -EROFS;
679 		goto out_timers;
680 	}
681 
682 	dbg_io("synchronize");
683 	for (i = 0; i < c->jhead_cnt; i++) {
684 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
685 
686 		cond_resched();
687 
688 		/*
689 		 * If the mutex is locked then wbuf is being changed, so
690 		 * synchronization is not necessary.
691 		 */
692 		if (mutex_is_locked(&wbuf->io_mutex))
693 			continue;
694 
695 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
696 		if (!wbuf->need_sync) {
697 			mutex_unlock(&wbuf->io_mutex);
698 			continue;
699 		}
700 
701 		err = ubifs_wbuf_sync_nolock(wbuf);
702 		mutex_unlock(&wbuf->io_mutex);
703 		if (err) {
704 			ubifs_err(c, "cannot sync write-buffer, error %d", err);
705 			ubifs_ro_mode(c, err);
706 			goto out_timers;
707 		}
708 	}
709 
710 	return 0;
711 
712 out_timers:
713 	/* Cancel all timers to prevent repeated errors */
714 	for (i = 0; i < c->jhead_cnt; i++) {
715 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
716 
717 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
718 		cancel_wbuf_timer_nolock(wbuf);
719 		mutex_unlock(&wbuf->io_mutex);
720 	}
721 	return err;
722 }
723 
724 /**
725  * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
726  * @wbuf: write-buffer
727  * @buf: node to write
728  * @len: node length
729  *
730  * This function writes data to flash via write-buffer @wbuf. This means that
731  * the last piece of the node won't reach the flash media immediately if it
732  * does not take whole max. write unit (@c->max_write_size). Instead, the node
733  * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
734  * because more data are appended to the write-buffer).
735  *
736  * This function returns zero in case of success and a negative error code in
737  * case of failure. If the node cannot be written because there is no more
738  * space in this logical eraseblock, %-ENOSPC is returned.
739  */
ubifs_wbuf_write_nolock(struct ubifs_wbuf * wbuf,void * buf,int len)740 int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
741 {
742 	struct ubifs_info *c = wbuf->c;
743 	int err, n, written = 0, aligned_len = ALIGN(len, 8);
744 
745 	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
746 	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
747 	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
748 	ubifs_assert(c, len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
749 	ubifs_assert(c, wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
750 	ubifs_assert(c, !(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
751 	ubifs_assert(c, wbuf->avail > 0 && wbuf->avail <= wbuf->size);
752 	ubifs_assert(c, wbuf->size >= c->min_io_size);
753 	ubifs_assert(c, wbuf->size <= c->max_write_size);
754 	ubifs_assert(c, wbuf->size % c->min_io_size == 0);
755 	ubifs_assert(c, mutex_is_locked(&wbuf->io_mutex));
756 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
757 	ubifs_assert(c, !c->space_fixup);
758 	if (c->leb_size - wbuf->offs >= c->max_write_size)
759 		ubifs_assert(c, !((wbuf->offs + wbuf->size) % c->max_write_size));
760 
761 	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
762 		err = -ENOSPC;
763 		goto out;
764 	}
765 
766 	cancel_wbuf_timer_nolock(wbuf);
767 
768 	if (c->ro_error)
769 		return -EROFS;
770 
771 	if (aligned_len <= wbuf->avail) {
772 		/*
773 		 * The node is not very large and fits entirely within
774 		 * write-buffer.
775 		 */
776 		memcpy(wbuf->buf + wbuf->used, buf, len);
777 		if (aligned_len > len) {
778 			ubifs_assert(c, aligned_len - len < 8);
779 			ubifs_pad(c, wbuf->buf + wbuf->used + len, aligned_len - len);
780 		}
781 
782 		if (aligned_len == wbuf->avail) {
783 			dbg_io("flush jhead %s wbuf to LEB %d:%d",
784 			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
785 			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
786 					      wbuf->offs, wbuf->size);
787 			if (err)
788 				goto out;
789 
790 			spin_lock(&wbuf->lock);
791 			wbuf->offs += wbuf->size;
792 			if (c->leb_size - wbuf->offs >= c->max_write_size)
793 				wbuf->size = c->max_write_size;
794 			else
795 				wbuf->size = c->leb_size - wbuf->offs;
796 			wbuf->avail = wbuf->size;
797 			wbuf->used = 0;
798 			wbuf->next_ino = 0;
799 			spin_unlock(&wbuf->lock);
800 		} else {
801 			spin_lock(&wbuf->lock);
802 			wbuf->avail -= aligned_len;
803 			wbuf->used += aligned_len;
804 			spin_unlock(&wbuf->lock);
805 		}
806 
807 		goto exit;
808 	}
809 
810 	if (wbuf->used) {
811 		/*
812 		 * The node is large enough and does not fit entirely within
813 		 * current available space. We have to fill and flush
814 		 * write-buffer and switch to the next max. write unit.
815 		 */
816 		dbg_io("flush jhead %s wbuf to LEB %d:%d",
817 		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
818 		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
819 		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
820 				      wbuf->size);
821 		if (err)
822 			goto out;
823 
824 		wbuf->offs += wbuf->size;
825 		len -= wbuf->avail;
826 		aligned_len -= wbuf->avail;
827 		written += wbuf->avail;
828 	} else if (wbuf->offs & (c->max_write_size - 1)) {
829 		/*
830 		 * The write-buffer offset is not aligned to
831 		 * @c->max_write_size and @wbuf->size is less than
832 		 * @c->max_write_size. Write @wbuf->size bytes to make sure the
833 		 * following writes are done in optimal @c->max_write_size
834 		 * chunks.
835 		 */
836 		dbg_io("write %d bytes to LEB %d:%d",
837 		       wbuf->size, wbuf->lnum, wbuf->offs);
838 		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
839 				      wbuf->size);
840 		if (err)
841 			goto out;
842 
843 		wbuf->offs += wbuf->size;
844 		len -= wbuf->size;
845 		aligned_len -= wbuf->size;
846 		written += wbuf->size;
847 	}
848 
849 	/*
850 	 * The remaining data may take more whole max. write units, so write the
851 	 * remains multiple to max. write unit size directly to the flash media.
852 	 * We align node length to 8-byte boundary because we anyway flash wbuf
853 	 * if the remaining space is less than 8 bytes.
854 	 */
855 	n = aligned_len >> c->max_write_shift;
856 	if (n) {
857 		int m = n - 1;
858 
859 		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
860 		       wbuf->offs);
861 
862 		if (m) {
863 			/* '(n-1)<<c->max_write_shift < len' is always true. */
864 			m <<= c->max_write_shift;
865 			err = ubifs_leb_write(c, wbuf->lnum, buf + written,
866 					      wbuf->offs, m);
867 			if (err)
868 				goto out;
869 			wbuf->offs += m;
870 			aligned_len -= m;
871 			len -= m;
872 			written += m;
873 		}
874 
875 		/*
876 		 * The non-written len of buf may be less than 'n' because
877 		 * parameter 'len' is not 8 bytes aligned, so here we read
878 		 * min(len, n) bytes from buf.
879 		 */
880 		n = 1 << c->max_write_shift;
881 		memcpy(wbuf->buf, buf + written, min(len, n));
882 		if (n > len) {
883 			ubifs_assert(c, n - len < 8);
884 			ubifs_pad(c, wbuf->buf + len, n - len);
885 		}
886 
887 		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, n);
888 		if (err)
889 			goto out;
890 		wbuf->offs += n;
891 		aligned_len -= n;
892 		len -= min(len, n);
893 		written += n;
894 	}
895 
896 	spin_lock(&wbuf->lock);
897 	if (aligned_len) {
898 		/*
899 		 * And now we have what's left and what does not take whole
900 		 * max. write unit, so write it to the write-buffer and we are
901 		 * done.
902 		 */
903 		memcpy(wbuf->buf, buf + written, len);
904 		if (aligned_len > len) {
905 			ubifs_assert(c, aligned_len - len < 8);
906 			ubifs_pad(c, wbuf->buf + len, aligned_len - len);
907 		}
908 	}
909 
910 	if (c->leb_size - wbuf->offs >= c->max_write_size)
911 		wbuf->size = c->max_write_size;
912 	else
913 		wbuf->size = c->leb_size - wbuf->offs;
914 	wbuf->avail = wbuf->size - aligned_len;
915 	wbuf->used = aligned_len;
916 	wbuf->next_ino = 0;
917 	spin_unlock(&wbuf->lock);
918 
919 exit:
920 	if (wbuf->sync_callback) {
921 		int free = c->leb_size - wbuf->offs - wbuf->used;
922 
923 		err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
924 		if (err)
925 			goto out;
926 	}
927 
928 	if (wbuf->used)
929 		new_wbuf_timer_nolock(c, wbuf);
930 
931 	return 0;
932 
933 out:
934 	ubifs_err(c, "cannot write %d bytes to LEB %d:%d, error %d",
935 		  len, wbuf->lnum, wbuf->offs, err);
936 	ubifs_dump_node(c, buf, written + len);
937 	dump_stack();
938 	ubifs_dump_leb(c, wbuf->lnum);
939 	return err;
940 }
941 
942 /**
943  * ubifs_write_node_hmac - write node to the media.
944  * @c: UBIFS file-system description object
945  * @buf: the node to write
946  * @len: node length
947  * @lnum: logical eraseblock number
948  * @offs: offset within the logical eraseblock
949  * @hmac_offs: offset of the HMAC within the node
950  *
951  * This function automatically fills node magic number, assigns sequence
952  * number, and calculates node CRC checksum. The length of the @buf buffer has
953  * to be aligned to the minimal I/O unit size. This function automatically
954  * appends padding node and padding bytes if needed. Returns zero in case of
955  * success and a negative error code in case of failure.
956  */
ubifs_write_node_hmac(struct ubifs_info * c,void * buf,int len,int lnum,int offs,int hmac_offs)957 int ubifs_write_node_hmac(struct ubifs_info *c, void *buf, int len, int lnum,
958 			  int offs, int hmac_offs)
959 {
960 	int err, buf_len = ALIGN(len, c->min_io_size);
961 
962 	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
963 	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
964 	       buf_len);
965 	ubifs_assert(c, lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
966 	ubifs_assert(c, offs % c->min_io_size == 0 && offs < c->leb_size);
967 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
968 	ubifs_assert(c, !c->space_fixup);
969 
970 	if (c->ro_error)
971 		return -EROFS;
972 
973 	err = ubifs_prepare_node_hmac(c, buf, len, hmac_offs, 1);
974 	if (err)
975 		return err;
976 
977 	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
978 	if (err)
979 		ubifs_dump_node(c, buf, len);
980 
981 	return err;
982 }
983 
984 /**
985  * ubifs_write_node - write node to the media.
986  * @c: UBIFS file-system description object
987  * @buf: the node to write
988  * @len: node length
989  * @lnum: logical eraseblock number
990  * @offs: offset within the logical eraseblock
991  *
992  * This function automatically fills node magic number, assigns sequence
993  * number, and calculates node CRC checksum. The length of the @buf buffer has
994  * to be aligned to the minimal I/O unit size. This function automatically
995  * appends padding node and padding bytes if needed. Returns zero in case of
996  * success and a negative error code in case of failure.
997  */
ubifs_write_node(struct ubifs_info * c,void * buf,int len,int lnum,int offs)998 int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
999 		     int offs)
1000 {
1001 	return ubifs_write_node_hmac(c, buf, len, lnum, offs, -1);
1002 }
1003 
1004 /**
1005  * ubifs_read_node_wbuf - read node from the media or write-buffer.
1006  * @wbuf: wbuf to check for un-written data
1007  * @buf: buffer to read to
1008  * @type: node type
1009  * @len: node length
1010  * @lnum: logical eraseblock number
1011  * @offs: offset within the logical eraseblock
1012  *
1013  * This function reads a node of known type and length, checks it and stores
1014  * in @buf. If the node partially or fully sits in the write-buffer, this
1015  * function takes data from the buffer, otherwise it reads the flash media.
1016  * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
1017  * error code in case of failure.
1018  */
ubifs_read_node_wbuf(struct ubifs_wbuf * wbuf,void * buf,int type,int len,int lnum,int offs)1019 int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
1020 			 int lnum, int offs)
1021 {
1022 	const struct ubifs_info *c = wbuf->c;
1023 	int err, rlen, overlap;
1024 	struct ubifs_ch *ch = buf;
1025 
1026 	dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
1027 	       dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
1028 	ubifs_assert(c, wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
1029 	ubifs_assert(c, !(offs & 7) && offs < c->leb_size);
1030 	ubifs_assert(c, type >= 0 && type < UBIFS_NODE_TYPES_CNT);
1031 
1032 	spin_lock(&wbuf->lock);
1033 	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
1034 	if (!overlap) {
1035 		/* We may safely unlock the write-buffer and read the data */
1036 		spin_unlock(&wbuf->lock);
1037 		return ubifs_read_node(c, buf, type, len, lnum, offs);
1038 	}
1039 
1040 	/* Don't read under wbuf */
1041 	rlen = wbuf->offs - offs;
1042 	if (rlen < 0)
1043 		rlen = 0;
1044 
1045 	/* Copy the rest from the write-buffer */
1046 	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
1047 	spin_unlock(&wbuf->lock);
1048 
1049 	if (rlen > 0) {
1050 		/* Read everything that goes before write-buffer */
1051 		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
1052 		if (err && err != -EBADMSG)
1053 			return err;
1054 	}
1055 
1056 	if (type != ch->node_type) {
1057 		ubifs_err(c, "bad node type (%d but expected %d)",
1058 			  ch->node_type, type);
1059 		goto out;
1060 	}
1061 
1062 	err = ubifs_check_node(c, buf, len, lnum, offs, 0, 0);
1063 	if (err) {
1064 		ubifs_err(c, "expected node type %d", type);
1065 		return err;
1066 	}
1067 
1068 	rlen = le32_to_cpu(ch->len);
1069 	if (rlen != len) {
1070 		ubifs_err(c, "bad node length %d, expected %d", rlen, len);
1071 		goto out;
1072 	}
1073 
1074 	return 0;
1075 
1076 out:
1077 	ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
1078 	ubifs_dump_node(c, buf, len);
1079 	dump_stack();
1080 	return -EINVAL;
1081 }
1082 
1083 /**
1084  * ubifs_read_node - read node.
1085  * @c: UBIFS file-system description object
1086  * @buf: buffer to read to
1087  * @type: node type
1088  * @len: node length (not aligned)
1089  * @lnum: logical eraseblock number
1090  * @offs: offset within the logical eraseblock
1091  *
1092  * This function reads a node of known type and length, checks it and
1093  * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
1094  * and a negative error code in case of failure.
1095  */
ubifs_read_node(const struct ubifs_info * c,void * buf,int type,int len,int lnum,int offs)1096 int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
1097 		    int lnum, int offs)
1098 {
1099 	int err, l;
1100 	struct ubifs_ch *ch = buf;
1101 
1102 	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
1103 	ubifs_assert(c, lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
1104 	ubifs_assert(c, len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
1105 	ubifs_assert(c, !(offs & 7) && offs < c->leb_size);
1106 	ubifs_assert(c, type >= 0 && type < UBIFS_NODE_TYPES_CNT);
1107 
1108 	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
1109 	if (err && err != -EBADMSG)
1110 		return err;
1111 
1112 	if (type != ch->node_type) {
1113 		ubifs_errc(c, "bad node type (%d but expected %d)",
1114 			   ch->node_type, type);
1115 		goto out;
1116 	}
1117 
1118 	err = ubifs_check_node(c, buf, len, lnum, offs, 0, 0);
1119 	if (err) {
1120 		ubifs_errc(c, "expected node type %d", type);
1121 		return err;
1122 	}
1123 
1124 	l = le32_to_cpu(ch->len);
1125 	if (l != len) {
1126 		ubifs_errc(c, "bad node length %d, expected %d", l, len);
1127 		goto out;
1128 	}
1129 
1130 	return 0;
1131 
1132 out:
1133 	ubifs_errc(c, "bad node at LEB %d:%d, LEB mapping status %d", lnum,
1134 		   offs, ubi_is_mapped(c->ubi, lnum));
1135 	if (!c->probing) {
1136 		ubifs_dump_node(c, buf, len);
1137 		dump_stack();
1138 	}
1139 	return -EINVAL;
1140 }
1141 
1142 /**
1143  * ubifs_wbuf_init - initialize write-buffer.
1144  * @c: UBIFS file-system description object
1145  * @wbuf: write-buffer to initialize
1146  *
1147  * This function initializes write-buffer. Returns zero in case of success
1148  * %-ENOMEM in case of failure.
1149  */
ubifs_wbuf_init(struct ubifs_info * c,struct ubifs_wbuf * wbuf)1150 int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
1151 {
1152 	size_t size;
1153 
1154 	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
1155 	if (!wbuf->buf)
1156 		return -ENOMEM;
1157 
1158 	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
1159 	wbuf->inodes = kmalloc(size, GFP_KERNEL);
1160 	if (!wbuf->inodes) {
1161 		kfree(wbuf->buf);
1162 		wbuf->buf = NULL;
1163 		return -ENOMEM;
1164 	}
1165 
1166 	wbuf->used = 0;
1167 	wbuf->lnum = wbuf->offs = -1;
1168 	/*
1169 	 * If the LEB starts at the max. write size aligned address, then
1170 	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
1171 	 * set it to something smaller so that it ends at the closest max.
1172 	 * write size boundary.
1173 	 */
1174 	size = c->max_write_size - (c->leb_start % c->max_write_size);
1175 	wbuf->avail = wbuf->size = size;
1176 	wbuf->sync_callback = NULL;
1177 	mutex_init(&wbuf->io_mutex);
1178 	spin_lock_init(&wbuf->lock);
1179 	wbuf->c = c;
1180 	wbuf->next_ino = 0;
1181 
1182 	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1183 	wbuf->timer.function = wbuf_timer_callback_nolock;
1184 	return 0;
1185 }
1186 
1187 /**
1188  * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
1189  * @wbuf: the write-buffer where to add
1190  * @inum: the inode number
1191  *
1192  * This function adds an inode number to the inode array of the write-buffer.
1193  */
ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf * wbuf,ino_t inum)1194 void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
1195 {
1196 	if (!wbuf->buf)
1197 		/* NOR flash or something similar */
1198 		return;
1199 
1200 	spin_lock(&wbuf->lock);
1201 	if (wbuf->used)
1202 		wbuf->inodes[wbuf->next_ino++] = inum;
1203 	spin_unlock(&wbuf->lock);
1204 }
1205 
1206 /**
1207  * wbuf_has_ino - returns if the wbuf contains data from the inode.
1208  * @wbuf: the write-buffer
1209  * @inum: the inode number
1210  *
1211  * This function returns with %1 if the write-buffer contains some data from the
1212  * given inode otherwise it returns with %0.
1213  */
wbuf_has_ino(struct ubifs_wbuf * wbuf,ino_t inum)1214 static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
1215 {
1216 	int i, ret = 0;
1217 
1218 	spin_lock(&wbuf->lock);
1219 	for (i = 0; i < wbuf->next_ino; i++)
1220 		if (inum == wbuf->inodes[i]) {
1221 			ret = 1;
1222 			break;
1223 		}
1224 	spin_unlock(&wbuf->lock);
1225 
1226 	return ret;
1227 }
1228 
1229 /**
1230  * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
1231  * @c: UBIFS file-system description object
1232  * @inode: inode to synchronize
1233  *
1234  * This function synchronizes write-buffers which contain nodes belonging to
1235  * @inode. Returns zero in case of success and a negative error code in case of
1236  * failure.
1237  */
ubifs_sync_wbufs_by_inode(struct ubifs_info * c,struct inode * inode)1238 int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
1239 {
1240 	int i, err = 0;
1241 
1242 	for (i = 0; i < c->jhead_cnt; i++) {
1243 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
1244 
1245 		if (i == GCHD)
1246 			/*
1247 			 * GC head is special, do not look at it. Even if the
1248 			 * head contains something related to this inode, it is
1249 			 * a _copy_ of corresponding on-flash node which sits
1250 			 * somewhere else.
1251 			 */
1252 			continue;
1253 
1254 		if (!wbuf_has_ino(wbuf, inode->i_ino))
1255 			continue;
1256 
1257 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
1258 		if (wbuf_has_ino(wbuf, inode->i_ino))
1259 			err = ubifs_wbuf_sync_nolock(wbuf);
1260 		mutex_unlock(&wbuf->io_mutex);
1261 
1262 		if (err) {
1263 			ubifs_ro_mode(c, err);
1264 			return err;
1265 		}
1266 	}
1267 	return 0;
1268 }
1269