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TOMOYO Linux Cross Reference
Linux/fs/ubifs/io.c

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

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