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

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  1 /*
  2  * This file is part of UBIFS.
  3  *
  4  * Copyright (C) 2006-2008 Nokia Corporation.
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 as published by
  8  * the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 13  * more details.
 14  *
 15  * You should have received a copy of the GNU General Public License along with
 16  * this program; if not, write to the Free Software Foundation, Inc., 51
 17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 18  *
 19  * Authors: Artem Bityutskiy (Битюцкий Артём)
 20  *          Adrian Hunter
 21  */
 22 
 23 /*
 24  * This file implements UBIFS superblock. The superblock is stored at the first
 25  * LEB of the volume and is never changed by UBIFS. Only user-space tools may
 26  * change it. The superblock node mostly contains geometry information.
 27  */
 28 
 29 #include "ubifs.h"
 30 #include <linux/slab.h>
 31 #include <linux/math64.h>
 32 #include <linux/uuid.h>
 33 
 34 /*
 35  * Default journal size in logical eraseblocks as a percent of total
 36  * flash size.
 37  */
 38 #define DEFAULT_JNL_PERCENT 5
 39 
 40 /* Default maximum journal size in bytes */
 41 #define DEFAULT_MAX_JNL (32*1024*1024)
 42 
 43 /* Default indexing tree fanout */
 44 #define DEFAULT_FANOUT 8
 45 
 46 /* Default number of data journal heads */
 47 #define DEFAULT_JHEADS_CNT 1
 48 
 49 /* Default positions of different LEBs in the main area */
 50 #define DEFAULT_IDX_LEB  0
 51 #define DEFAULT_DATA_LEB 1
 52 #define DEFAULT_GC_LEB   2
 53 
 54 /* Default number of LEB numbers in LPT's save table */
 55 #define DEFAULT_LSAVE_CNT 256
 56 
 57 /* Default reserved pool size as a percent of maximum free space */
 58 #define DEFAULT_RP_PERCENT 5
 59 
 60 /* The default maximum size of reserved pool in bytes */
 61 #define DEFAULT_MAX_RP_SIZE (5*1024*1024)
 62 
 63 /* Default time granularity in nanoseconds */
 64 #define DEFAULT_TIME_GRAN 1000000000
 65 
 66 /**
 67  * create_default_filesystem - format empty UBI volume.
 68  * @c: UBIFS file-system description object
 69  *
 70  * This function creates default empty file-system. Returns zero in case of
 71  * success and a negative error code in case of failure.
 72  */
 73 static int create_default_filesystem(struct ubifs_info *c)
 74 {
 75         struct ubifs_sb_node *sup;
 76         struct ubifs_mst_node *mst;
 77         struct ubifs_idx_node *idx;
 78         struct ubifs_branch *br;
 79         struct ubifs_ino_node *ino;
 80         struct ubifs_cs_node *cs;
 81         union ubifs_key key;
 82         int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
 83         int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
 84         int min_leb_cnt = UBIFS_MIN_LEB_CNT;
 85         long long tmp64, main_bytes;
 86         __le64 tmp_le64;
 87 
 88         /* Some functions called from here depend on the @c->key_len filed */
 89         c->key_len = UBIFS_SK_LEN;
 90 
 91         /*
 92          * First of all, we have to calculate default file-system geometry -
 93          * log size, journal size, etc.
 94          */
 95         if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
 96                 /* We can first multiply then divide and have no overflow */
 97                 jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
 98         else
 99                 jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
100 
101         if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
102                 jnl_lebs = UBIFS_MIN_JNL_LEBS;
103         if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
104                 jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
105 
106         /*
107          * The log should be large enough to fit reference nodes for all bud
108          * LEBs. Because buds do not have to start from the beginning of LEBs
109          * (half of the LEB may contain committed data), the log should
110          * generally be larger, make it twice as large.
111          */
112         tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
113         log_lebs = tmp / c->leb_size;
114         /* Plus one LEB reserved for commit */
115         log_lebs += 1;
116         if (c->leb_cnt - min_leb_cnt > 8) {
117                 /* And some extra space to allow writes while committing */
118                 log_lebs += 1;
119                 min_leb_cnt += 1;
120         }
121 
122         max_buds = jnl_lebs - log_lebs;
123         if (max_buds < UBIFS_MIN_BUD_LEBS)
124                 max_buds = UBIFS_MIN_BUD_LEBS;
125 
126         /*
127          * Orphan nodes are stored in a separate area. One node can store a lot
128          * of orphan inode numbers, but when new orphan comes we just add a new
129          * orphan node. At some point the nodes are consolidated into one
130          * orphan node.
131          */
132         orph_lebs = UBIFS_MIN_ORPH_LEBS;
133         if (c->leb_cnt - min_leb_cnt > 1)
134                 /*
135                  * For debugging purposes it is better to have at least 2
136                  * orphan LEBs, because the orphan subsystem would need to do
137                  * consolidations and would be stressed more.
138                  */
139                 orph_lebs += 1;
140 
141         main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
142         main_lebs -= orph_lebs;
143 
144         lpt_first = UBIFS_LOG_LNUM + log_lebs;
145         c->lsave_cnt = DEFAULT_LSAVE_CNT;
146         c->max_leb_cnt = c->leb_cnt;
147         err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
148                                     &big_lpt);
149         if (err)
150                 return err;
151 
152         dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
153                 lpt_first + lpt_lebs - 1);
154 
155         main_first = c->leb_cnt - main_lebs;
156 
157         /* Create default superblock */
158         tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
159         sup = kzalloc(tmp, GFP_KERNEL);
160         if (!sup)
161                 return -ENOMEM;
162 
163         tmp64 = (long long)max_buds * c->leb_size;
164         if (big_lpt)
165                 sup_flags |= UBIFS_FLG_BIGLPT;
166 
167         sup->ch.node_type  = UBIFS_SB_NODE;
168         sup->key_hash      = UBIFS_KEY_HASH_R5;
169         sup->flags         = cpu_to_le32(sup_flags);
170         sup->min_io_size   = cpu_to_le32(c->min_io_size);
171         sup->leb_size      = cpu_to_le32(c->leb_size);
172         sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
173         sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
174         sup->max_bud_bytes = cpu_to_le64(tmp64);
175         sup->log_lebs      = cpu_to_le32(log_lebs);
176         sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
177         sup->orph_lebs     = cpu_to_le32(orph_lebs);
178         sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
179         sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
180         sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
181         sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
182         sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
183         if (c->mount_opts.override_compr)
184                 sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
185         else
186                 sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
187 
188         generate_random_uuid(sup->uuid);
189 
190         main_bytes = (long long)main_lebs * c->leb_size;
191         tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
192         if (tmp64 > DEFAULT_MAX_RP_SIZE)
193                 tmp64 = DEFAULT_MAX_RP_SIZE;
194         sup->rp_size = cpu_to_le64(tmp64);
195         sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
196 
197         err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
198         kfree(sup);
199         if (err)
200                 return err;
201 
202         dbg_gen("default superblock created at LEB 0:0");
203 
204         /* Create default master node */
205         mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
206         if (!mst)
207                 return -ENOMEM;
208 
209         mst->ch.node_type = UBIFS_MST_NODE;
210         mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
211         mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
212         mst->cmt_no       = 0;
213         mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
214         mst->root_offs    = 0;
215         tmp = ubifs_idx_node_sz(c, 1);
216         mst->root_len     = cpu_to_le32(tmp);
217         mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
218         mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
219         mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
220         mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
221         mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
222         mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
223         mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
224         mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
225         mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
226         mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
227         mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
228         mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
229         mst->lscan_lnum   = cpu_to_le32(main_first);
230         mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
231         mst->idx_lebs     = cpu_to_le32(1);
232         mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
233 
234         /* Calculate lprops statistics */
235         tmp64 = main_bytes;
236         tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
237         tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
238         mst->total_free = cpu_to_le64(tmp64);
239 
240         tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
241         ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
242                           UBIFS_INO_NODE_SZ;
243         tmp64 += ino_waste;
244         tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
245         mst->total_dirty = cpu_to_le64(tmp64);
246 
247         /*  The indexing LEB does not contribute to dark space */
248         tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
249         mst->total_dark = cpu_to_le64(tmp64);
250 
251         mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
252 
253         err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
254         if (err) {
255                 kfree(mst);
256                 return err;
257         }
258         err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1,
259                                0);
260         kfree(mst);
261         if (err)
262                 return err;
263 
264         dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
265 
266         /* Create the root indexing node */
267         tmp = ubifs_idx_node_sz(c, 1);
268         idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
269         if (!idx)
270                 return -ENOMEM;
271 
272         c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
273         c->key_hash = key_r5_hash;
274 
275         idx->ch.node_type = UBIFS_IDX_NODE;
276         idx->child_cnt = cpu_to_le16(1);
277         ino_key_init(c, &key, UBIFS_ROOT_INO);
278         br = ubifs_idx_branch(c, idx, 0);
279         key_write_idx(c, &key, &br->key);
280         br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
281         br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
282         err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0);
283         kfree(idx);
284         if (err)
285                 return err;
286 
287         dbg_gen("default root indexing node created LEB %d:0",
288                 main_first + DEFAULT_IDX_LEB);
289 
290         /* Create default root inode */
291         tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
292         ino = kzalloc(tmp, GFP_KERNEL);
293         if (!ino)
294                 return -ENOMEM;
295 
296         ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
297         ino->ch.node_type = UBIFS_INO_NODE;
298         ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
299         ino->nlink = cpu_to_le32(2);
300         tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
301         ino->atime_sec   = tmp_le64;
302         ino->ctime_sec   = tmp_le64;
303         ino->mtime_sec   = tmp_le64;
304         ino->atime_nsec  = 0;
305         ino->ctime_nsec  = 0;
306         ino->mtime_nsec  = 0;
307         ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
308         ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
309 
310         /* Set compression enabled by default */
311         ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
312 
313         err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
314                                main_first + DEFAULT_DATA_LEB, 0);
315         kfree(ino);
316         if (err)
317                 return err;
318 
319         dbg_gen("root inode created at LEB %d:0",
320                 main_first + DEFAULT_DATA_LEB);
321 
322         /*
323          * The first node in the log has to be the commit start node. This is
324          * always the case during normal file-system operation. Write a fake
325          * commit start node to the log.
326          */
327         tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
328         cs = kzalloc(tmp, GFP_KERNEL);
329         if (!cs)
330                 return -ENOMEM;
331 
332         cs->ch.node_type = UBIFS_CS_NODE;
333         err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
334         kfree(cs);
335         if (err)
336                 return err;
337 
338         ubifs_msg(c, "default file-system created");
339         return 0;
340 }
341 
342 /**
343  * validate_sb - validate superblock node.
344  * @c: UBIFS file-system description object
345  * @sup: superblock node
346  *
347  * This function validates superblock node @sup. Since most of data was read
348  * from the superblock and stored in @c, the function validates fields in @c
349  * instead. Returns zero in case of success and %-EINVAL in case of validation
350  * failure.
351  */
352 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
353 {
354         long long max_bytes;
355         int err = 1, min_leb_cnt;
356 
357         if (!c->key_hash) {
358                 err = 2;
359                 goto failed;
360         }
361 
362         if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
363                 err = 3;
364                 goto failed;
365         }
366 
367         if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
368                 ubifs_err(c, "min. I/O unit mismatch: %d in superblock, %d real",
369                           le32_to_cpu(sup->min_io_size), c->min_io_size);
370                 goto failed;
371         }
372 
373         if (le32_to_cpu(sup->leb_size) != c->leb_size) {
374                 ubifs_err(c, "LEB size mismatch: %d in superblock, %d real",
375                           le32_to_cpu(sup->leb_size), c->leb_size);
376                 goto failed;
377         }
378 
379         if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
380             c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
381             c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
382             c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
383                 err = 4;
384                 goto failed;
385         }
386 
387         /*
388          * Calculate minimum allowed amount of main area LEBs. This is very
389          * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
390          * have just read from the superblock.
391          */
392         min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
393         min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
394 
395         if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
396                 ubifs_err(c, "bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
397                           c->leb_cnt, c->vi.size, min_leb_cnt);
398                 goto failed;
399         }
400 
401         if (c->max_leb_cnt < c->leb_cnt) {
402                 ubifs_err(c, "max. LEB count %d less than LEB count %d",
403                           c->max_leb_cnt, c->leb_cnt);
404                 goto failed;
405         }
406 
407         if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
408                 ubifs_err(c, "too few main LEBs count %d, must be at least %d",
409                           c->main_lebs, UBIFS_MIN_MAIN_LEBS);
410                 goto failed;
411         }
412 
413         max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
414         if (c->max_bud_bytes < max_bytes) {
415                 ubifs_err(c, "too small journal (%lld bytes), must be at least %lld bytes",
416                           c->max_bud_bytes, max_bytes);
417                 goto failed;
418         }
419 
420         max_bytes = (long long)c->leb_size * c->main_lebs;
421         if (c->max_bud_bytes > max_bytes) {
422                 ubifs_err(c, "too large journal size (%lld bytes), only %lld bytes available in the main area",
423                           c->max_bud_bytes, max_bytes);
424                 goto failed;
425         }
426 
427         if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
428             c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
429                 err = 9;
430                 goto failed;
431         }
432 
433         if (c->fanout < UBIFS_MIN_FANOUT ||
434             ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
435                 err = 10;
436                 goto failed;
437         }
438 
439         if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
440             c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
441             c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
442                 err = 11;
443                 goto failed;
444         }
445 
446         if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
447             c->orph_lebs + c->main_lebs != c->leb_cnt) {
448                 err = 12;
449                 goto failed;
450         }
451 
452         if (c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
453                 err = 13;
454                 goto failed;
455         }
456 
457         if (c->rp_size < 0 || max_bytes < c->rp_size) {
458                 err = 14;
459                 goto failed;
460         }
461 
462         if (le32_to_cpu(sup->time_gran) > 1000000000 ||
463             le32_to_cpu(sup->time_gran) < 1) {
464                 err = 15;
465                 goto failed;
466         }
467 
468         return 0;
469 
470 failed:
471         ubifs_err(c, "bad superblock, error %d", err);
472         ubifs_dump_node(c, sup);
473         return -EINVAL;
474 }
475 
476 /**
477  * ubifs_read_sb_node - read superblock node.
478  * @c: UBIFS file-system description object
479  *
480  * This function returns a pointer to the superblock node or a negative error
481  * code. Note, the user of this function is responsible of kfree()'ing the
482  * returned superblock buffer.
483  */
484 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
485 {
486         struct ubifs_sb_node *sup;
487         int err;
488 
489         sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
490         if (!sup)
491                 return ERR_PTR(-ENOMEM);
492 
493         err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
494                               UBIFS_SB_LNUM, 0);
495         if (err) {
496                 kfree(sup);
497                 return ERR_PTR(err);
498         }
499 
500         return sup;
501 }
502 
503 /**
504  * ubifs_write_sb_node - write superblock node.
505  * @c: UBIFS file-system description object
506  * @sup: superblock node read with 'ubifs_read_sb_node()'
507  *
508  * This function returns %0 on success and a negative error code on failure.
509  */
510 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
511 {
512         int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
513 
514         ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
515         return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
516 }
517 
518 /**
519  * ubifs_read_superblock - read superblock.
520  * @c: UBIFS file-system description object
521  *
522  * This function finds, reads and checks the superblock. If an empty UBI volume
523  * is being mounted, this function creates default superblock. Returns zero in
524  * case of success, and a negative error code in case of failure.
525  */
526 int ubifs_read_superblock(struct ubifs_info *c)
527 {
528         int err, sup_flags;
529         struct ubifs_sb_node *sup;
530 
531         if (c->empty) {
532                 err = create_default_filesystem(c);
533                 if (err)
534                         return err;
535         }
536 
537         sup = ubifs_read_sb_node(c);
538         if (IS_ERR(sup))
539                 return PTR_ERR(sup);
540 
541         c->fmt_version = le32_to_cpu(sup->fmt_version);
542         c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
543 
544         /*
545          * The software supports all previous versions but not future versions,
546          * due to the unavailability of time-travelling equipment.
547          */
548         if (c->fmt_version > UBIFS_FORMAT_VERSION) {
549                 ubifs_assert(!c->ro_media || c->ro_mount);
550                 if (!c->ro_mount ||
551                     c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
552                         ubifs_err(c, "on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
553                                   c->fmt_version, c->ro_compat_version,
554                                   UBIFS_FORMAT_VERSION,
555                                   UBIFS_RO_COMPAT_VERSION);
556                         if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
557                                 ubifs_msg(c, "only R/O mounting is possible");
558                                 err = -EROFS;
559                         } else
560                                 err = -EINVAL;
561                         goto out;
562                 }
563 
564                 /*
565                  * The FS is mounted R/O, and the media format is
566                  * R/O-compatible with the UBIFS implementation, so we can
567                  * mount.
568                  */
569                 c->rw_incompat = 1;
570         }
571 
572         if (c->fmt_version < 3) {
573                 ubifs_err(c, "on-flash format version %d is not supported",
574                           c->fmt_version);
575                 err = -EINVAL;
576                 goto out;
577         }
578 
579         switch (sup->key_hash) {
580         case UBIFS_KEY_HASH_R5:
581                 c->key_hash = key_r5_hash;
582                 c->key_hash_type = UBIFS_KEY_HASH_R5;
583                 break;
584 
585         case UBIFS_KEY_HASH_TEST:
586                 c->key_hash = key_test_hash;
587                 c->key_hash_type = UBIFS_KEY_HASH_TEST;
588                 break;
589         };
590 
591         c->key_fmt = sup->key_fmt;
592 
593         switch (c->key_fmt) {
594         case UBIFS_SIMPLE_KEY_FMT:
595                 c->key_len = UBIFS_SK_LEN;
596                 break;
597         default:
598                 ubifs_err(c, "unsupported key format");
599                 err = -EINVAL;
600                 goto out;
601         }
602 
603         c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
604         c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
605         c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
606         c->log_lebs      = le32_to_cpu(sup->log_lebs);
607         c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
608         c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
609         c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
610         c->fanout        = le32_to_cpu(sup->fanout);
611         c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
612         c->rp_size       = le64_to_cpu(sup->rp_size);
613         c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
614         c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
615         sup_flags        = le32_to_cpu(sup->flags);
616         if (!c->mount_opts.override_compr)
617                 c->default_compr = le16_to_cpu(sup->default_compr);
618 
619         c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
620         memcpy(&c->uuid, &sup->uuid, 16);
621         c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
622         c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
623 
624         /* Automatically increase file system size to the maximum size */
625         c->old_leb_cnt = c->leb_cnt;
626         if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
627                 c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
628                 if (c->ro_mount)
629                         dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
630                                 c->old_leb_cnt, c->leb_cnt);
631                 else {
632                         dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
633                                 c->old_leb_cnt, c->leb_cnt);
634                         sup->leb_cnt = cpu_to_le32(c->leb_cnt);
635                         err = ubifs_write_sb_node(c, sup);
636                         if (err)
637                                 goto out;
638                         c->old_leb_cnt = c->leb_cnt;
639                 }
640         }
641 
642         c->log_bytes = (long long)c->log_lebs * c->leb_size;
643         c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
644         c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
645         c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
646         c->orph_first = c->lpt_last + 1;
647         c->orph_last = c->orph_first + c->orph_lebs - 1;
648         c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
649         c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
650         c->main_first = c->leb_cnt - c->main_lebs;
651 
652         err = validate_sb(c, sup);
653 out:
654         kfree(sup);
655         return err;
656 }
657 
658 /**
659  * fixup_leb - fixup/unmap an LEB containing free space.
660  * @c: UBIFS file-system description object
661  * @lnum: the LEB number to fix up
662  * @len: number of used bytes in LEB (starting at offset 0)
663  *
664  * This function reads the contents of the given LEB number @lnum, then fixes
665  * it up, so that empty min. I/O units in the end of LEB are actually erased on
666  * flash (rather than being just all-0xff real data). If the LEB is completely
667  * empty, it is simply unmapped.
668  */
669 static int fixup_leb(struct ubifs_info *c, int lnum, int len)
670 {
671         int err;
672 
673         ubifs_assert(len >= 0);
674         ubifs_assert(len % c->min_io_size == 0);
675         ubifs_assert(len < c->leb_size);
676 
677         if (len == 0) {
678                 dbg_mnt("unmap empty LEB %d", lnum);
679                 return ubifs_leb_unmap(c, lnum);
680         }
681 
682         dbg_mnt("fixup LEB %d, data len %d", lnum, len);
683         err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
684         if (err)
685                 return err;
686 
687         return ubifs_leb_change(c, lnum, c->sbuf, len);
688 }
689 
690 /**
691  * fixup_free_space - find & remap all LEBs containing free space.
692  * @c: UBIFS file-system description object
693  *
694  * This function walks through all LEBs in the filesystem and fiexes up those
695  * containing free/empty space.
696  */
697 static int fixup_free_space(struct ubifs_info *c)
698 {
699         int lnum, err = 0;
700         struct ubifs_lprops *lprops;
701 
702         ubifs_get_lprops(c);
703 
704         /* Fixup LEBs in the master area */
705         for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
706                 err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
707                 if (err)
708                         goto out;
709         }
710 
711         /* Unmap unused log LEBs */
712         lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
713         while (lnum != c->ltail_lnum) {
714                 err = fixup_leb(c, lnum, 0);
715                 if (err)
716                         goto out;
717                 lnum = ubifs_next_log_lnum(c, lnum);
718         }
719 
720         /*
721          * Fixup the log head which contains the only a CS node at the
722          * beginning.
723          */
724         err = fixup_leb(c, c->lhead_lnum,
725                         ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
726         if (err)
727                 goto out;
728 
729         /* Fixup LEBs in the LPT area */
730         for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
731                 int free = c->ltab[lnum - c->lpt_first].free;
732 
733                 if (free > 0) {
734                         err = fixup_leb(c, lnum, c->leb_size - free);
735                         if (err)
736                                 goto out;
737                 }
738         }
739 
740         /* Unmap LEBs in the orphans area */
741         for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
742                 err = fixup_leb(c, lnum, 0);
743                 if (err)
744                         goto out;
745         }
746 
747         /* Fixup LEBs in the main area */
748         for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
749                 lprops = ubifs_lpt_lookup(c, lnum);
750                 if (IS_ERR(lprops)) {
751                         err = PTR_ERR(lprops);
752                         goto out;
753                 }
754 
755                 if (lprops->free > 0) {
756                         err = fixup_leb(c, lnum, c->leb_size - lprops->free);
757                         if (err)
758                                 goto out;
759                 }
760         }
761 
762 out:
763         ubifs_release_lprops(c);
764         return err;
765 }
766 
767 /**
768  * ubifs_fixup_free_space - find & fix all LEBs with free space.
769  * @c: UBIFS file-system description object
770  *
771  * This function fixes up LEBs containing free space on first mount, if the
772  * appropriate flag was set when the FS was created. Each LEB with one or more
773  * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
774  * the free space is actually erased. E.g., this is necessary for some NAND
775  * chips, since the free space may have been programmed like real "0xff" data
776  * (generating a non-0xff ECC), causing future writes to the not-really-erased
777  * NAND pages to behave badly. After the space is fixed up, the superblock flag
778  * is cleared, so that this is skipped for all future mounts.
779  */
780 int ubifs_fixup_free_space(struct ubifs_info *c)
781 {
782         int err;
783         struct ubifs_sb_node *sup;
784 
785         ubifs_assert(c->space_fixup);
786         ubifs_assert(!c->ro_mount);
787 
788         ubifs_msg(c, "start fixing up free space");
789 
790         err = fixup_free_space(c);
791         if (err)
792                 return err;
793 
794         sup = ubifs_read_sb_node(c);
795         if (IS_ERR(sup))
796                 return PTR_ERR(sup);
797 
798         /* Free-space fixup is no longer required */
799         c->space_fixup = 0;
800         sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
801 
802         err = ubifs_write_sb_node(c, sup);
803         kfree(sup);
804         if (err)
805                 return err;
806 
807         ubifs_msg(c, "free space fixup complete");
808         return err;
809 }
810 

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