[JFFS2] Optimise reading of eraseblock summary nodes
[linux-2.6.git] / fs / jffs2 / scan.c
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright (C) 2001-2003 Red Hat, Inc.
5  *
6  * Created by David Woodhouse <dwmw2@infradead.org>
7  *
8  * For licensing information, see the file 'LICENCE' in this directory.
9  *
10  * $Id: scan.c,v 1.125 2005/09/30 13:59:13 dedekind Exp $
11  *
12  */
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/pagemap.h>
18 #include <linux/crc32.h>
19 #include <linux/compiler.h>
20 #include "nodelist.h"
21 #include "summary.h"
22 #include "debug.h"
23
24 #define DEFAULT_EMPTY_SCAN_SIZE 1024
25
26 #define noisy_printk(noise, args...) do { \
27         if (*(noise)) { \
28                 printk(KERN_NOTICE args); \
29                  (*(noise))--; \
30                  if (!(*(noise))) { \
31                          printk(KERN_NOTICE "Further such events for this erase block will not be printed\n"); \
32                  } \
33         } \
34 } while(0)
35
36 static uint32_t pseudo_random;
37
38 static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
39                                   unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s);
40
41 /* These helper functions _must_ increase ofs and also do the dirty/used space accounting.
42  * Returning an error will abort the mount - bad checksums etc. should just mark the space
43  * as dirty.
44  */
45 static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
46                                  struct jffs2_raw_inode *ri, uint32_t ofs, struct jffs2_summary *s);
47 static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
48                                  struct jffs2_raw_dirent *rd, uint32_t ofs, struct jffs2_summary *s);
49
50 static inline int min_free(struct jffs2_sb_info *c)
51 {
52         uint32_t min = 2 * sizeof(struct jffs2_raw_inode);
53 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
54         if (!jffs2_can_mark_obsolete(c) && min < c->wbuf_pagesize)
55                 return c->wbuf_pagesize;
56 #endif
57         return min;
58
59 }
60
61 static inline uint32_t EMPTY_SCAN_SIZE(uint32_t sector_size) {
62         if (sector_size < DEFAULT_EMPTY_SCAN_SIZE)
63                 return sector_size;
64         else
65                 return DEFAULT_EMPTY_SCAN_SIZE;
66 }
67
68 int jffs2_scan_medium(struct jffs2_sb_info *c)
69 {
70         int i, ret;
71         uint32_t empty_blocks = 0, bad_blocks = 0;
72         unsigned char *flashbuf = NULL;
73         uint32_t buf_size = 0;
74         struct jffs2_summary *s = NULL; /* summary info collected by the scan process */
75 #ifndef __ECOS
76         size_t pointlen;
77
78         if (c->mtd->point) {
79                 ret = c->mtd->point (c->mtd, 0, c->mtd->size, &pointlen, &flashbuf);
80                 if (!ret && pointlen < c->mtd->size) {
81                         /* Don't muck about if it won't let us point to the whole flash */
82                         D1(printk(KERN_DEBUG "MTD point returned len too short: 0x%zx\n", pointlen));
83                         c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
84                         flashbuf = NULL;
85                 }
86                 if (ret)
87                         D1(printk(KERN_DEBUG "MTD point failed %d\n", ret));
88         }
89 #endif
90         if (!flashbuf) {
91                 /* For NAND it's quicker to read a whole eraseblock at a time,
92                    apparently */
93                 if (jffs2_cleanmarker_oob(c))
94                         buf_size = c->sector_size;
95                 else
96                         buf_size = PAGE_SIZE;
97
98                 /* Respect kmalloc limitations */
99                 if (buf_size > 128*1024)
100                         buf_size = 128*1024;
101
102                 D1(printk(KERN_DEBUG "Allocating readbuf of %d bytes\n", buf_size));
103                 flashbuf = kmalloc(buf_size, GFP_KERNEL);
104                 if (!flashbuf)
105                         return -ENOMEM;
106         }
107
108         if (jffs2_sum_active()) {
109                 s = kmalloc(sizeof(struct jffs2_summary), GFP_KERNEL);
110                 if (!s) {
111                         JFFS2_WARNING("Can't allocate memory for summary\n");
112                         return -ENOMEM;
113                 }
114                 memset(s, 0, sizeof(struct jffs2_summary));
115         }
116
117         for (i=0; i<c->nr_blocks; i++) {
118                 struct jffs2_eraseblock *jeb = &c->blocks[i];
119
120                 /* reset summary info for next eraseblock scan */
121                 jffs2_sum_reset_collected(s);
122
123                 ret = jffs2_scan_eraseblock(c, jeb, buf_size?flashbuf:(flashbuf+jeb->offset),
124                                                 buf_size, s);
125
126                 if (ret < 0)
127                         goto out;
128
129                 jffs2_dbg_acct_paranoia_check_nolock(c, jeb);
130
131                 /* Now decide which list to put it on */
132                 switch(ret) {
133                 case BLK_STATE_ALLFF:
134                         /*
135                          * Empty block.   Since we can't be sure it
136                          * was entirely erased, we just queue it for erase
137                          * again.  It will be marked as such when the erase
138                          * is complete.  Meanwhile we still count it as empty
139                          * for later checks.
140                          */
141                         empty_blocks++;
142                         list_add(&jeb->list, &c->erase_pending_list);
143                         c->nr_erasing_blocks++;
144                         break;
145
146                 case BLK_STATE_CLEANMARKER:
147                         /* Only a CLEANMARKER node is valid */
148                         if (!jeb->dirty_size) {
149                                 /* It's actually free */
150                                 list_add(&jeb->list, &c->free_list);
151                                 c->nr_free_blocks++;
152                         } else {
153                                 /* Dirt */
154                                 D1(printk(KERN_DEBUG "Adding all-dirty block at 0x%08x to erase_pending_list\n", jeb->offset));
155                                 list_add(&jeb->list, &c->erase_pending_list);
156                                 c->nr_erasing_blocks++;
157                         }
158                         break;
159
160                 case BLK_STATE_CLEAN:
161                         /* Full (or almost full) of clean data. Clean list */
162                         list_add(&jeb->list, &c->clean_list);
163                         break;
164
165                 case BLK_STATE_PARTDIRTY:
166                         /* Some data, but not full. Dirty list. */
167                         /* We want to remember the block with most free space
168                         and stick it in the 'nextblock' position to start writing to it. */
169                         if (jeb->free_size > min_free(c) &&
170                                         (!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
171                                 /* Better candidate for the next writes to go to */
172                                 if (c->nextblock) {
173                                         c->nextblock->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
174                                         c->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
175                                         c->free_size -= c->nextblock->free_size;
176                                         c->wasted_size -= c->nextblock->wasted_size;
177                                         c->nextblock->free_size = c->nextblock->wasted_size = 0;
178                                         if (VERYDIRTY(c, c->nextblock->dirty_size)) {
179                                                 list_add(&c->nextblock->list, &c->very_dirty_list);
180                                         } else {
181                                                 list_add(&c->nextblock->list, &c->dirty_list);
182                                         }
183                                         /* deleting summary information of the old nextblock */
184                                         jffs2_sum_reset_collected(c->summary);
185                                 }
186                                 /* update collected summary infromation for the current nextblock */
187                                 jffs2_sum_move_collected(c, s);
188                                 D1(printk(KERN_DEBUG "jffs2_scan_medium(): new nextblock = 0x%08x\n", jeb->offset));
189                                 c->nextblock = jeb;
190                         } else {
191                                 jeb->dirty_size += jeb->free_size + jeb->wasted_size;
192                                 c->dirty_size += jeb->free_size + jeb->wasted_size;
193                                 c->free_size -= jeb->free_size;
194                                 c->wasted_size -= jeb->wasted_size;
195                                 jeb->free_size = jeb->wasted_size = 0;
196                                 if (VERYDIRTY(c, jeb->dirty_size)) {
197                                         list_add(&jeb->list, &c->very_dirty_list);
198                                 } else {
199                                         list_add(&jeb->list, &c->dirty_list);
200                                 }
201                         }
202                         break;
203
204                 case BLK_STATE_ALLDIRTY:
205                         /* Nothing valid - not even a clean marker. Needs erasing. */
206                         /* For now we just put it on the erasing list. We'll start the erases later */
207                         D1(printk(KERN_NOTICE "JFFS2: Erase block at 0x%08x is not formatted. It will be erased\n", jeb->offset));
208                         list_add(&jeb->list, &c->erase_pending_list);
209                         c->nr_erasing_blocks++;
210                         break;
211
212                 case BLK_STATE_BADBLOCK:
213                         D1(printk(KERN_NOTICE "JFFS2: Block at 0x%08x is bad\n", jeb->offset));
214                         list_add(&jeb->list, &c->bad_list);
215                         c->bad_size += c->sector_size;
216                         c->free_size -= c->sector_size;
217                         bad_blocks++;
218                         break;
219                 default:
220                         printk(KERN_WARNING "jffs2_scan_medium(): unknown block state\n");
221                         BUG();
222                 }
223         }
224
225         /* Nextblock dirty is always seen as wasted, because we cannot recycle it now */
226         if (c->nextblock && (c->nextblock->dirty_size)) {
227                 c->nextblock->wasted_size += c->nextblock->dirty_size;
228                 c->wasted_size += c->nextblock->dirty_size;
229                 c->dirty_size -= c->nextblock->dirty_size;
230                 c->nextblock->dirty_size = 0;
231         }
232 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
233         if (!jffs2_can_mark_obsolete(c) && c->wbuf_pagesize && c->nextblock && (c->nextblock->free_size % c->wbuf_pagesize)) {
234                 /* If we're going to start writing into a block which already
235                    contains data, and the end of the data isn't page-aligned,
236                    skip a little and align it. */
237
238                 uint32_t skip = c->nextblock->free_size % c->wbuf_pagesize;
239
240                 D1(printk(KERN_DEBUG "jffs2_scan_medium(): Skipping %d bytes in nextblock to ensure page alignment\n",
241                           skip));
242                 c->nextblock->wasted_size += skip;
243                 c->wasted_size += skip;
244
245                 c->nextblock->free_size -= skip;
246                 c->free_size -= skip;
247         }
248 #endif
249         if (c->nr_erasing_blocks) {
250                 if ( !c->used_size && ((c->nr_free_blocks+empty_blocks+bad_blocks)!= c->nr_blocks || bad_blocks == c->nr_blocks) ) {
251                         printk(KERN_NOTICE "Cowardly refusing to erase blocks on filesystem with no valid JFFS2 nodes\n");
252                         printk(KERN_NOTICE "empty_blocks %d, bad_blocks %d, c->nr_blocks %d\n",empty_blocks,bad_blocks,c->nr_blocks);
253                         ret = -EIO;
254                         goto out;
255                 }
256                 jffs2_erase_pending_trigger(c);
257         }
258         ret = 0;
259  out:
260         if (buf_size)
261                 kfree(flashbuf);
262 #ifndef __ECOS
263         else
264                 c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
265 #endif
266         if (s)
267                 kfree(s);
268
269         return ret;
270 }
271
272 int jffs2_fill_scan_buf (struct jffs2_sb_info *c, void *buf,
273                                 uint32_t ofs, uint32_t len)
274 {
275         int ret;
276         size_t retlen;
277
278         ret = jffs2_flash_read(c, ofs, len, &retlen, buf);
279         if (ret) {
280                 D1(printk(KERN_WARNING "mtd->read(0x%x bytes from 0x%x) returned %d\n", len, ofs, ret));
281                 return ret;
282         }
283         if (retlen < len) {
284                 D1(printk(KERN_WARNING "Read at 0x%x gave only 0x%zx bytes\n", ofs, retlen));
285                 return -EIO;
286         }
287         return 0;
288 }
289
290 int jffs2_scan_classify_jeb(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
291 {
292         if ((jeb->used_size + jeb->unchecked_size) == PAD(c->cleanmarker_size) && !jeb->dirty_size
293                 && (!jeb->first_node || !jeb->first_node->next_phys) )
294                 return BLK_STATE_CLEANMARKER;
295
296         /* move blocks with max 4 byte dirty space to cleanlist */
297         else if (!ISDIRTY(c->sector_size - (jeb->used_size + jeb->unchecked_size))) {
298                 c->dirty_size -= jeb->dirty_size;
299                 c->wasted_size += jeb->dirty_size;
300                 jeb->wasted_size += jeb->dirty_size;
301                 jeb->dirty_size = 0;
302                 return BLK_STATE_CLEAN;
303         } else if (jeb->used_size || jeb->unchecked_size)
304                 return BLK_STATE_PARTDIRTY;
305         else
306                 return BLK_STATE_ALLDIRTY;
307 }
308
309 /* Called with 'buf_size == 0' if buf is in fact a pointer _directly_ into
310    the flash, XIP-style */
311 static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
312                                   unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
313         struct jffs2_unknown_node *node;
314         struct jffs2_unknown_node crcnode;
315         uint32_t ofs, prevofs;
316         uint32_t hdr_crc, buf_ofs, buf_len;
317         int err;
318         int noise = 0;
319
320
321 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
322         int cleanmarkerfound = 0;
323 #endif
324
325         ofs = jeb->offset;
326         prevofs = jeb->offset - 1;
327
328         D1(printk(KERN_DEBUG "jffs2_scan_eraseblock(): Scanning block at 0x%x\n", ofs));
329
330 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
331         if (jffs2_cleanmarker_oob(c)) {
332                 int ret = jffs2_check_nand_cleanmarker(c, jeb);
333                 D2(printk(KERN_NOTICE "jffs_check_nand_cleanmarker returned %d\n",ret));
334                 /* Even if it's not found, we still scan to see
335                    if the block is empty. We use this information
336                    to decide whether to erase it or not. */
337                 switch (ret) {
338                 case 0:         cleanmarkerfound = 1; break;
339                 case 1:         break;
340                 case 2:         return BLK_STATE_BADBLOCK;
341                 case 3:         return BLK_STATE_ALLDIRTY; /* Block has failed to erase min. once */
342                 default:        return ret;
343                 }
344         }
345 #endif
346
347         if (jffs2_sum_active()) {
348                 struct jffs2_sum_marker *sm;
349                 void *sumptr = NULL;
350                 uint32_t sumlen;
351               
352                 if (!buf_size) {
353                         /* XIP case. Just look, point at the summary if it's there */
354                         sm = (void *)buf + jeb->offset - sizeof(*sm);
355                         if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
356                                 sumptr = buf + je32_to_cpu(sm->offset);
357                                 sumlen = c->sector_size - je32_to_cpu(sm->offset);
358                         }
359                 } else {
360                         /* If NAND flash, read a whole page of it. Else just the end */
361                         if (c->wbuf_pagesize)
362                                 buf_len = c->wbuf_pagesize;
363                         else
364                                 buf_len = sizeof(*sm);
365
366                         /* Read as much as we want into the _end_ of the preallocated buffer */
367                         err = jffs2_fill_scan_buf(c, buf + buf_size - buf_len, 
368                                                   jeb->offset + c->sector_size - buf_len,
369                                                   buf_len);                             
370                         if (err)
371                                 return err;
372
373                         sm = (void *)buf + buf_size - sizeof(*sm);
374                         if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
375                                 sumlen = c->sector_size - je32_to_cpu(sm->offset);
376                                 sumptr = buf + buf_size - sumlen;
377
378                                 /* Now, make sure the summary itself is available */
379                                 if (sumlen > buf_size) {
380                                         /* Need to kmalloc for this. */
381                                         sumptr = kmalloc(sumlen, GFP_KERNEL);
382                                         if (!sumptr)
383                                                 return -ENOMEM;
384                                         memcpy(sumptr + sumlen - buf_len, buf + buf_size - buf_len, buf_len);
385                                 }
386                                 if (buf_len < sumlen) {
387                                         /* Need to read more so that the entire summary node is present */
388                                         err = jffs2_fill_scan_buf(c, sumptr, 
389                                                                   jeb->offset + c->sector_size - sumlen,
390                                                                   sumlen - buf_len);                            
391                                         if (err)
392                                                 return err;
393                                 }
394                         }
395
396                 }
397
398                 if (sumptr) {
399                         err = jffs2_sum_scan_sumnode(c, jeb, sumptr, sumlen, &pseudo_random);
400                         if (err)
401                                 return err;
402                         if (buf_size && sumlen > buf_size)
403                                 kfree(sumptr);
404                 }
405         }
406
407         buf_ofs = jeb->offset;
408
409         if (!buf_size) {
410                 /* This is the XIP case -- we're reading _directly_ from the flash chip */
411                 buf_len = c->sector_size;
412         } else {
413                 buf_len = EMPTY_SCAN_SIZE(c->sector_size);
414                 err = jffs2_fill_scan_buf(c, buf, buf_ofs, buf_len);
415                 if (err)
416                         return err;
417         }
418
419         /* We temporarily use 'ofs' as a pointer into the buffer/jeb */
420         ofs = 0;
421
422         /* Scan only 4KiB of 0xFF before declaring it's empty */
423         while(ofs < EMPTY_SCAN_SIZE(c->sector_size) && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
424                 ofs += 4;
425
426         if (ofs == EMPTY_SCAN_SIZE(c->sector_size)) {
427 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
428                 if (jffs2_cleanmarker_oob(c)) {
429                         /* scan oob, take care of cleanmarker */
430                         int ret = jffs2_check_oob_empty(c, jeb, cleanmarkerfound);
431                         D2(printk(KERN_NOTICE "jffs2_check_oob_empty returned %d\n",ret));
432                         switch (ret) {
433                         case 0:         return cleanmarkerfound ? BLK_STATE_CLEANMARKER : BLK_STATE_ALLFF;
434                         case 1:         return BLK_STATE_ALLDIRTY;
435                         default:        return ret;
436                         }
437                 }
438 #endif
439                 D1(printk(KERN_DEBUG "Block at 0x%08x is empty (erased)\n", jeb->offset));
440                 if (c->cleanmarker_size == 0)
441                         return BLK_STATE_CLEANMARKER;   /* don't bother with re-erase */
442                 else
443                         return BLK_STATE_ALLFF; /* OK to erase if all blocks are like this */
444         }
445         if (ofs) {
446                 D1(printk(KERN_DEBUG "Free space at %08x ends at %08x\n", jeb->offset,
447                           jeb->offset + ofs));
448                 DIRTY_SPACE(ofs);
449         }
450
451         /* Now ofs is a complete physical flash offset as it always was... */
452         ofs += jeb->offset;
453
454         noise = 10;
455
456         dbg_summary("no summary found in jeb 0x%08x. Apply original scan.\n",jeb->offset);
457
458 scan_more:
459         while(ofs < jeb->offset + c->sector_size) {
460
461                 jffs2_dbg_acct_paranoia_check_nolock(c, jeb);
462
463                 cond_resched();
464
465                 if (ofs & 3) {
466                         printk(KERN_WARNING "Eep. ofs 0x%08x not word-aligned!\n", ofs);
467                         ofs = PAD(ofs);
468                         continue;
469                 }
470                 if (ofs == prevofs) {
471                         printk(KERN_WARNING "ofs 0x%08x has already been seen. Skipping\n", ofs);
472                         DIRTY_SPACE(4);
473                         ofs += 4;
474                         continue;
475                 }
476                 prevofs = ofs;
477
478                 if (jeb->offset + c->sector_size < ofs + sizeof(*node)) {
479                         D1(printk(KERN_DEBUG "Fewer than %zd bytes left to end of block. (%x+%x<%x+%zx) Not reading\n", sizeof(struct jffs2_unknown_node),
480                                   jeb->offset, c->sector_size, ofs, sizeof(*node)));
481                         DIRTY_SPACE((jeb->offset + c->sector_size)-ofs);
482                         break;
483                 }
484
485                 if (buf_ofs + buf_len < ofs + sizeof(*node)) {
486                         buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
487                         D1(printk(KERN_DEBUG "Fewer than %zd bytes (node header) left to end of buf. Reading 0x%x at 0x%08x\n",
488                                   sizeof(struct jffs2_unknown_node), buf_len, ofs));
489                         err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
490                         if (err)
491                                 return err;
492                         buf_ofs = ofs;
493                 }
494
495                 node = (struct jffs2_unknown_node *)&buf[ofs-buf_ofs];
496
497                 if (*(uint32_t *)(&buf[ofs-buf_ofs]) == 0xffffffff) {
498                         uint32_t inbuf_ofs;
499                         uint32_t empty_start;
500
501                         empty_start = ofs;
502                         ofs += 4;
503
504                         D1(printk(KERN_DEBUG "Found empty flash at 0x%08x\n", ofs));
505                 more_empty:
506                         inbuf_ofs = ofs - buf_ofs;
507                         while (inbuf_ofs < buf_len) {
508                                 if (*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff) {
509                                         printk(KERN_WARNING "Empty flash at 0x%08x ends at 0x%08x\n",
510                                                empty_start, ofs);
511                                         DIRTY_SPACE(ofs-empty_start);
512                                         goto scan_more;
513                                 }
514
515                                 inbuf_ofs+=4;
516                                 ofs += 4;
517                         }
518                         /* Ran off end. */
519                         D1(printk(KERN_DEBUG "Empty flash to end of buffer at 0x%08x\n", ofs));
520
521                         /* If we're only checking the beginning of a block with a cleanmarker,
522                            bail now */
523                         if (buf_ofs == jeb->offset && jeb->used_size == PAD(c->cleanmarker_size) &&
524                             c->cleanmarker_size && !jeb->dirty_size && !jeb->first_node->next_phys) {
525                                 D1(printk(KERN_DEBUG "%d bytes at start of block seems clean... assuming all clean\n", EMPTY_SCAN_SIZE(c->sector_size)));
526                                 return BLK_STATE_CLEANMARKER;
527                         }
528
529                         /* See how much more there is to read in this eraseblock... */
530                         buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
531                         if (!buf_len) {
532                                 /* No more to read. Break out of main loop without marking
533                                    this range of empty space as dirty (because it's not) */
534                                 D1(printk(KERN_DEBUG "Empty flash at %08x runs to end of block. Treating as free_space\n",
535                                           empty_start));
536                                 break;
537                         }
538                         D1(printk(KERN_DEBUG "Reading another 0x%x at 0x%08x\n", buf_len, ofs));
539                         err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
540                         if (err)
541                                 return err;
542                         buf_ofs = ofs;
543                         goto more_empty;
544                 }
545
546                 if (ofs == jeb->offset && je16_to_cpu(node->magic) == KSAMTIB_CIGAM_2SFFJ) {
547                         printk(KERN_WARNING "Magic bitmask is backwards at offset 0x%08x. Wrong endian filesystem?\n", ofs);
548                         DIRTY_SPACE(4);
549                         ofs += 4;
550                         continue;
551                 }
552                 if (je16_to_cpu(node->magic) == JFFS2_DIRTY_BITMASK) {
553                         D1(printk(KERN_DEBUG "Dirty bitmask at 0x%08x\n", ofs));
554                         DIRTY_SPACE(4);
555                         ofs += 4;
556                         continue;
557                 }
558                 if (je16_to_cpu(node->magic) == JFFS2_OLD_MAGIC_BITMASK) {
559                         printk(KERN_WARNING "Old JFFS2 bitmask found at 0x%08x\n", ofs);
560                         printk(KERN_WARNING "You cannot use older JFFS2 filesystems with newer kernels\n");
561                         DIRTY_SPACE(4);
562                         ofs += 4;
563                         continue;
564                 }
565                 if (je16_to_cpu(node->magic) != JFFS2_MAGIC_BITMASK) {
566                         /* OK. We're out of possibilities. Whinge and move on */
567                         noisy_printk(&noise, "jffs2_scan_eraseblock(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n",
568                                      JFFS2_MAGIC_BITMASK, ofs,
569                                      je16_to_cpu(node->magic));
570                         DIRTY_SPACE(4);
571                         ofs += 4;
572                         continue;
573                 }
574                 /* We seem to have a node of sorts. Check the CRC */
575                 crcnode.magic = node->magic;
576                 crcnode.nodetype = cpu_to_je16( je16_to_cpu(node->nodetype) | JFFS2_NODE_ACCURATE);
577                 crcnode.totlen = node->totlen;
578                 hdr_crc = crc32(0, &crcnode, sizeof(crcnode)-4);
579
580                 if (hdr_crc != je32_to_cpu(node->hdr_crc)) {
581                         noisy_printk(&noise, "jffs2_scan_eraseblock(): Node at 0x%08x {0x%04x, 0x%04x, 0x%08x) has invalid CRC 0x%08x (calculated 0x%08x)\n",
582                                      ofs, je16_to_cpu(node->magic),
583                                      je16_to_cpu(node->nodetype),
584                                      je32_to_cpu(node->totlen),
585                                      je32_to_cpu(node->hdr_crc),
586                                      hdr_crc);
587                         DIRTY_SPACE(4);
588                         ofs += 4;
589                         continue;
590                 }
591
592                 if (ofs + je32_to_cpu(node->totlen) >
593                     jeb->offset + c->sector_size) {
594                         /* Eep. Node goes over the end of the erase block. */
595                         printk(KERN_WARNING "Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
596                                ofs, je32_to_cpu(node->totlen));
597                         printk(KERN_WARNING "Perhaps the file system was created with the wrong erase size?\n");
598                         DIRTY_SPACE(4);
599                         ofs += 4;
600                         continue;
601                 }
602
603                 if (!(je16_to_cpu(node->nodetype) & JFFS2_NODE_ACCURATE)) {
604                         /* Wheee. This is an obsoleted node */
605                         D2(printk(KERN_DEBUG "Node at 0x%08x is obsolete. Skipping\n", ofs));
606                         DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
607                         ofs += PAD(je32_to_cpu(node->totlen));
608                         continue;
609                 }
610
611                 switch(je16_to_cpu(node->nodetype)) {
612                 case JFFS2_NODETYPE_INODE:
613                         if (buf_ofs + buf_len < ofs + sizeof(struct jffs2_raw_inode)) {
614                                 buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
615                                 D1(printk(KERN_DEBUG "Fewer than %zd bytes (inode node) left to end of buf. Reading 0x%x at 0x%08x\n",
616                                           sizeof(struct jffs2_raw_inode), buf_len, ofs));
617                                 err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
618                                 if (err)
619                                         return err;
620                                 buf_ofs = ofs;
621                                 node = (void *)buf;
622                         }
623                         err = jffs2_scan_inode_node(c, jeb, (void *)node, ofs, s);
624                         if (err) return err;
625                         ofs += PAD(je32_to_cpu(node->totlen));
626                         break;
627
628                 case JFFS2_NODETYPE_DIRENT:
629                         if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
630                                 buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
631                                 D1(printk(KERN_DEBUG "Fewer than %d bytes (dirent node) left to end of buf. Reading 0x%x at 0x%08x\n",
632                                           je32_to_cpu(node->totlen), buf_len, ofs));
633                                 err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
634                                 if (err)
635                                         return err;
636                                 buf_ofs = ofs;
637                                 node = (void *)buf;
638                         }
639                         err = jffs2_scan_dirent_node(c, jeb, (void *)node, ofs, s);
640                         if (err) return err;
641                         ofs += PAD(je32_to_cpu(node->totlen));
642                         break;
643
644                 case JFFS2_NODETYPE_CLEANMARKER:
645                         D1(printk(KERN_DEBUG "CLEANMARKER node found at 0x%08x\n", ofs));
646                         if (je32_to_cpu(node->totlen) != c->cleanmarker_size) {
647                                 printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x has totlen 0x%x != normal 0x%x\n",
648                                        ofs, je32_to_cpu(node->totlen), c->cleanmarker_size);
649                                 DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
650                                 ofs += PAD(sizeof(struct jffs2_unknown_node));
651                         } else if (jeb->first_node) {
652                                 printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x, not first node in block (0x%08x)\n", ofs, jeb->offset);
653                                 DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
654                                 ofs += PAD(sizeof(struct jffs2_unknown_node));
655                         } else {
656                                 struct jffs2_raw_node_ref *marker_ref = jffs2_alloc_raw_node_ref();
657                                 if (!marker_ref) {
658                                         printk(KERN_NOTICE "Failed to allocate node ref for clean marker\n");
659                                         return -ENOMEM;
660                                 }
661                                 marker_ref->next_in_ino = NULL;
662                                 marker_ref->next_phys = NULL;
663                                 marker_ref->flash_offset = ofs | REF_NORMAL;
664                                 marker_ref->__totlen = c->cleanmarker_size;
665                                 jeb->first_node = jeb->last_node = marker_ref;
666
667                                 USED_SPACE(PAD(c->cleanmarker_size));
668                                 ofs += PAD(c->cleanmarker_size);
669                         }
670                         break;
671
672                 case JFFS2_NODETYPE_PADDING:
673                         if (jffs2_sum_active())
674                                 jffs2_sum_add_padding_mem(s, je32_to_cpu(node->totlen));
675                         DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
676                         ofs += PAD(je32_to_cpu(node->totlen));
677                         break;
678
679                 default:
680                         switch (je16_to_cpu(node->nodetype) & JFFS2_COMPAT_MASK) {
681                         case JFFS2_FEATURE_ROCOMPAT:
682                                 printk(KERN_NOTICE "Read-only compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
683                                 c->flags |= JFFS2_SB_FLAG_RO;
684                                 if (!(jffs2_is_readonly(c)))
685                                         return -EROFS;
686                                 DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
687                                 ofs += PAD(je32_to_cpu(node->totlen));
688                                 break;
689
690                         case JFFS2_FEATURE_INCOMPAT:
691                                 printk(KERN_NOTICE "Incompatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
692                                 return -EINVAL;
693
694                         case JFFS2_FEATURE_RWCOMPAT_DELETE:
695                                 D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
696                                 DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
697                                 ofs += PAD(je32_to_cpu(node->totlen));
698                                 break;
699
700                         case JFFS2_FEATURE_RWCOMPAT_COPY:
701                                 D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
702                                 USED_SPACE(PAD(je32_to_cpu(node->totlen)));
703                                 ofs += PAD(je32_to_cpu(node->totlen));
704                                 break;
705                         }
706                 }
707         }
708
709         if (jffs2_sum_active()) {
710                 if (PAD(s->sum_size + JFFS2_SUMMARY_FRAME_SIZE) > jeb->free_size) {
711                         dbg_summary("There is not enough space for "
712                                 "summary information, disabling for this jeb!\n");
713                         jffs2_sum_disable_collecting(s);
714                 }
715         }
716
717         D1(printk(KERN_DEBUG "Block at 0x%08x: free 0x%08x, dirty 0x%08x, unchecked 0x%08x, used 0x%08x\n", jeb->offset,
718                   jeb->free_size, jeb->dirty_size, jeb->unchecked_size, jeb->used_size));
719
720         /* mark_node_obsolete can add to wasted !! */
721         if (jeb->wasted_size) {
722                 jeb->dirty_size += jeb->wasted_size;
723                 c->dirty_size += jeb->wasted_size;
724                 c->wasted_size -= jeb->wasted_size;
725                 jeb->wasted_size = 0;
726         }
727
728         return jffs2_scan_classify_jeb(c, jeb);
729 }
730
731 struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uint32_t ino)
732 {
733         struct jffs2_inode_cache *ic;
734
735         ic = jffs2_get_ino_cache(c, ino);
736         if (ic)
737                 return ic;
738
739         if (ino > c->highest_ino)
740                 c->highest_ino = ino;
741
742         ic = jffs2_alloc_inode_cache();
743         if (!ic) {
744                 printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of inode cache failed\n");
745                 return NULL;
746         }
747         memset(ic, 0, sizeof(*ic));
748
749         ic->ino = ino;
750         ic->nodes = (void *)ic;
751         jffs2_add_ino_cache(c, ic);
752         if (ino == 1)
753                 ic->nlink = 1;
754         return ic;
755 }
756
757 static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
758                                  struct jffs2_raw_inode *ri, uint32_t ofs, struct jffs2_summary *s)
759 {
760         struct jffs2_raw_node_ref *raw;
761         struct jffs2_inode_cache *ic;
762         uint32_t ino = je32_to_cpu(ri->ino);
763
764         D1(printk(KERN_DEBUG "jffs2_scan_inode_node(): Node at 0x%08x\n", ofs));
765
766         /* We do very little here now. Just check the ino# to which we should attribute
767            this node; we can do all the CRC checking etc. later. There's a tradeoff here --
768            we used to scan the flash once only, reading everything we want from it into
769            memory, then building all our in-core data structures and freeing the extra
770            information. Now we allow the first part of the mount to complete a lot quicker,
771            but we have to go _back_ to the flash in order to finish the CRC checking, etc.
772            Which means that the _full_ amount of time to get to proper write mode with GC
773            operational may actually be _longer_ than before. Sucks to be me. */
774
775         raw = jffs2_alloc_raw_node_ref();
776         if (!raw) {
777                 printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of node reference failed\n");
778                 return -ENOMEM;
779         }
780
781         ic = jffs2_get_ino_cache(c, ino);
782         if (!ic) {
783                 /* Inocache get failed. Either we read a bogus ino# or it's just genuinely the
784                    first node we found for this inode. Do a CRC check to protect against the former
785                    case */
786                 uint32_t crc = crc32(0, ri, sizeof(*ri)-8);
787
788                 if (crc != je32_to_cpu(ri->node_crc)) {
789                         printk(KERN_NOTICE "jffs2_scan_inode_node(): CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
790                                ofs, je32_to_cpu(ri->node_crc), crc);
791                         /* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
792                         DIRTY_SPACE(PAD(je32_to_cpu(ri->totlen)));
793                         jffs2_free_raw_node_ref(raw);
794                         return 0;
795                 }
796                 ic = jffs2_scan_make_ino_cache(c, ino);
797                 if (!ic) {
798                         jffs2_free_raw_node_ref(raw);
799                         return -ENOMEM;
800                 }
801         }
802
803         /* Wheee. It worked */
804
805         raw->flash_offset = ofs | REF_UNCHECKED;
806         raw->__totlen = PAD(je32_to_cpu(ri->totlen));
807         raw->next_phys = NULL;
808         raw->next_in_ino = ic->nodes;
809
810         ic->nodes = raw;
811         if (!jeb->first_node)
812                 jeb->first_node = raw;
813         if (jeb->last_node)
814                 jeb->last_node->next_phys = raw;
815         jeb->last_node = raw;
816
817         D1(printk(KERN_DEBUG "Node is ino #%u, version %d. Range 0x%x-0x%x\n",
818                   je32_to_cpu(ri->ino), je32_to_cpu(ri->version),
819                   je32_to_cpu(ri->offset),
820                   je32_to_cpu(ri->offset)+je32_to_cpu(ri->dsize)));
821
822         pseudo_random += je32_to_cpu(ri->version);
823
824         UNCHECKED_SPACE(PAD(je32_to_cpu(ri->totlen)));
825
826         if (jffs2_sum_active()) {
827                 jffs2_sum_add_inode_mem(s, ri, ofs - jeb->offset);
828         }
829
830         return 0;
831 }
832
833 static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
834                                   struct jffs2_raw_dirent *rd, uint32_t ofs, struct jffs2_summary *s)
835 {
836         struct jffs2_raw_node_ref *raw;
837         struct jffs2_full_dirent *fd;
838         struct jffs2_inode_cache *ic;
839         uint32_t crc;
840
841         D1(printk(KERN_DEBUG "jffs2_scan_dirent_node(): Node at 0x%08x\n", ofs));
842
843         /* We don't get here unless the node is still valid, so we don't have to
844            mask in the ACCURATE bit any more. */
845         crc = crc32(0, rd, sizeof(*rd)-8);
846
847         if (crc != je32_to_cpu(rd->node_crc)) {
848                 printk(KERN_NOTICE "jffs2_scan_dirent_node(): Node CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
849                        ofs, je32_to_cpu(rd->node_crc), crc);
850                 /* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
851                 DIRTY_SPACE(PAD(je32_to_cpu(rd->totlen)));
852                 return 0;
853         }
854
855         pseudo_random += je32_to_cpu(rd->version);
856
857         fd = jffs2_alloc_full_dirent(rd->nsize+1);
858         if (!fd) {
859                 return -ENOMEM;
860         }
861         memcpy(&fd->name, rd->name, rd->nsize);
862         fd->name[rd->nsize] = 0;
863
864         crc = crc32(0, fd->name, rd->nsize);
865         if (crc != je32_to_cpu(rd->name_crc)) {
866                 printk(KERN_NOTICE "jffs2_scan_dirent_node(): Name CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
867                        ofs, je32_to_cpu(rd->name_crc), crc);
868                 D1(printk(KERN_NOTICE "Name for which CRC failed is (now) '%s', ino #%d\n", fd->name, je32_to_cpu(rd->ino)));
869                 jffs2_free_full_dirent(fd);
870                 /* FIXME: Why do we believe totlen? */
871                 /* We believe totlen because the CRC on the node _header_ was OK, just the name failed. */
872                 DIRTY_SPACE(PAD(je32_to_cpu(rd->totlen)));
873                 return 0;
874         }
875         raw = jffs2_alloc_raw_node_ref();
876         if (!raw) {
877                 jffs2_free_full_dirent(fd);
878                 printk(KERN_NOTICE "jffs2_scan_dirent_node(): allocation of node reference failed\n");
879                 return -ENOMEM;
880         }
881         ic = jffs2_scan_make_ino_cache(c, je32_to_cpu(rd->pino));
882         if (!ic) {
883                 jffs2_free_full_dirent(fd);
884                 jffs2_free_raw_node_ref(raw);
885                 return -ENOMEM;
886         }
887
888         raw->__totlen = PAD(je32_to_cpu(rd->totlen));
889         raw->flash_offset = ofs | REF_PRISTINE;
890         raw->next_phys = NULL;
891         raw->next_in_ino = ic->nodes;
892         ic->nodes = raw;
893         if (!jeb->first_node)
894                 jeb->first_node = raw;
895         if (jeb->last_node)
896                 jeb->last_node->next_phys = raw;
897         jeb->last_node = raw;
898
899         fd->raw = raw;
900         fd->next = NULL;
901         fd->version = je32_to_cpu(rd->version);
902         fd->ino = je32_to_cpu(rd->ino);
903         fd->nhash = full_name_hash(fd->name, rd->nsize);
904         fd->type = rd->type;
905         USED_SPACE(PAD(je32_to_cpu(rd->totlen)));
906         jffs2_add_fd_to_list(c, fd, &ic->scan_dents);
907
908         if (jffs2_sum_active()) {
909                 jffs2_sum_add_dirent_mem(s, rd, ofs - jeb->offset);
910         }
911
912         return 0;
913 }
914
915 static int count_list(struct list_head *l)
916 {
917         uint32_t count = 0;
918         struct list_head *tmp;
919
920         list_for_each(tmp, l) {
921                 count++;
922         }
923         return count;
924 }
925
926 /* Note: This breaks if list_empty(head). I don't care. You
927    might, if you copy this code and use it elsewhere :) */
928 static void rotate_list(struct list_head *head, uint32_t count)
929 {
930         struct list_head *n = head->next;
931
932         list_del(head);
933         while(count--) {
934                 n = n->next;
935         }
936         list_add(head, n);
937 }
938
939 void jffs2_rotate_lists(struct jffs2_sb_info *c)
940 {
941         uint32_t x;
942         uint32_t rotateby;
943
944         x = count_list(&c->clean_list);
945         if (x) {
946                 rotateby = pseudo_random % x;
947                 rotate_list((&c->clean_list), rotateby);
948         }
949
950         x = count_list(&c->very_dirty_list);
951         if (x) {
952                 rotateby = pseudo_random % x;
953                 rotate_list((&c->very_dirty_list), rotateby);
954         }
955
956         x = count_list(&c->dirty_list);
957         if (x) {
958                 rotateby = pseudo_random % x;
959                 rotate_list((&c->dirty_list), rotateby);
960         }
961
962         x = count_list(&c->erasable_list);
963         if (x) {
964                 rotateby = pseudo_random % x;
965                 rotate_list((&c->erasable_list), rotateby);
966         }
967
968         if (c->nr_erasing_blocks) {
969                 rotateby = pseudo_random % c->nr_erasing_blocks;
970                 rotate_list((&c->erase_pending_list), rotateby);
971         }
972
973         if (c->nr_free_blocks) {
974                 rotateby = pseudo_random % c->nr_free_blocks;
975                 rotate_list((&c->free_list), rotateby);
976         }
977 }