1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * NFTL mount code with extensive checks
4 *
5 * Author: Fabrice Bellard (fabrice.bellard@netgem.com)
6 * Copyright �� 2000 Netgem S.A.
7 * Copyright �� 1999-2010 David Woodhouse <dwmw2@infradead.org>
8 */
9
10#include <linux/kernel.h>
11#include <asm/errno.h>
12#include <linux/delay.h>
13#include <linux/slab.h>
14#include <linux/mtd/mtd.h>
15#include <linux/mtd/rawnand.h>
16#include <linux/mtd/nftl.h>
17
18#define SECTORSIZE 512
19
20/* find_boot_record: Find the NFTL Media Header and its Spare copy which contains the
21 *	various device information of the NFTL partition and Bad Unit Table. Update
22 *	the ReplUnitTable[] table according to the Bad Unit Table. ReplUnitTable[]
23 *	is used for management of Erase Unit in other routines in nftl.c and nftlmount.c
24 */
25static int find_boot_record(struct NFTLrecord *nftl)
26{
27	struct nftl_uci1 h1;
28	unsigned int block, boot_record_count = 0;
29	size_t retlen;
30	u8 buf[SECTORSIZE];
31	struct NFTLMediaHeader *mh = &nftl->MediaHdr;
32	struct mtd_info *mtd = nftl->mbd.mtd;
33	unsigned int i;
34
35        /* Assume logical EraseSize == physical erasesize for starting the scan.
36	   We'll sort it out later if we find a MediaHeader which says otherwise */
37	/* Actually, we won't.  The new DiskOnChip driver has already scanned
38	   the MediaHeader and adjusted the virtual erasesize it presents in
39	   the mtd device accordingly.  We could even get rid of
40	   nftl->EraseSize if there were any point in doing so. */
41	nftl->EraseSize = nftl->mbd.mtd->erasesize;
42        nftl->nb_blocks = (u32)nftl->mbd.mtd->size / nftl->EraseSize;
43
44	nftl->MediaUnit = BLOCK_NIL;
45	nftl->SpareMediaUnit = BLOCK_NIL;
46
47	/* search for a valid boot record */
48	for (block = 0; block < nftl->nb_blocks; block++) {
49		int ret;
50
51		/* Check for ANAND header first. Then can whinge if it's found but later
52		   checks fail */
53		ret = mtd_read(mtd, block * nftl->EraseSize, SECTORSIZE,
54			       &retlen, buf);
55		/* We ignore ret in case the ECC of the MediaHeader is invalid
56		   (which is apparently acceptable) */
57		if (retlen != SECTORSIZE) {
58			static int warncount = 5;
59
60			if (warncount) {
61				printk(KERN_WARNING "Block read at 0x%x of mtd%d failed: %d\n",
62				       block * nftl->EraseSize, nftl->mbd.mtd->index, ret);
63				if (!--warncount)
64					printk(KERN_WARNING "Further failures for this block will not be printed\n");
65			}
66			continue;
67		}
68
69		if (retlen < 6 || memcmp(buf, "ANAND", 6)) {
70			/* ANAND\0 not found. Continue */
71#if 0
72			printk(KERN_DEBUG "ANAND header not found at 0x%x in mtd%d\n",
73			       block * nftl->EraseSize, nftl->mbd.mtd->index);
74#endif
75			continue;
76		}
77
78		/* To be safer with BIOS, also use erase mark as discriminant */
79		ret = nftl_read_oob(mtd, block * nftl->EraseSize +
80					 SECTORSIZE + 8, 8, &retlen,
81					 (char *)&h1);
82		if (ret < 0) {
83			printk(KERN_WARNING "ANAND header found at 0x%x in mtd%d, but OOB data read failed (err %d)\n",
84			       block * nftl->EraseSize, nftl->mbd.mtd->index, ret);
85			continue;
86		}
87
88#if 0 /* Some people seem to have devices without ECC or erase marks
89	 on the Media Header blocks. There are enough other sanity
90	 checks in here that we can probably do without it.
91      */
92		if (le16_to_cpu(h1.EraseMark | h1.EraseMark1) != ERASE_MARK) {
93			printk(KERN_NOTICE "ANAND header found at 0x%x in mtd%d, but erase mark not present (0x%04x,0x%04x instead)\n",
94			       block * nftl->EraseSize, nftl->mbd.mtd->index,
95			       le16_to_cpu(h1.EraseMark), le16_to_cpu(h1.EraseMark1));
96			continue;
97		}
98
99		/* Finally reread to check ECC */
100		ret = mtd->read(mtd, block * nftl->EraseSize, SECTORSIZE,
101				&retlen, buf);
102		if (ret < 0) {
103			printk(KERN_NOTICE "ANAND header found at 0x%x in mtd%d, but ECC read failed (err %d)\n",
104			       block * nftl->EraseSize, nftl->mbd.mtd->index, ret);
105			continue;
106		}
107
108		/* Paranoia. Check the ANAND header is still there after the ECC read */
109		if (memcmp(buf, "ANAND", 6)) {
110			printk(KERN_NOTICE "ANAND header found at 0x%x in mtd%d, but went away on reread!\n",
111			       block * nftl->EraseSize, nftl->mbd.mtd->index);
112			printk(KERN_NOTICE "New data are: %6ph\n", buf);
113			continue;
114		}
115#endif
116		/* OK, we like it. */
117
118		if (boot_record_count) {
119			/* We've already processed one. So we just check if
120			   this one is the same as the first one we found */
121			if (memcmp(mh, buf, sizeof(struct NFTLMediaHeader))) {
122				printk(KERN_NOTICE "NFTL Media Headers at 0x%x and 0x%x disagree.\n",
123				       nftl->MediaUnit * nftl->EraseSize, block * nftl->EraseSize);
124				/* if (debug) Print both side by side */
125				if (boot_record_count < 2) {
126					/* We haven't yet seen two real ones */
127					return -1;
128				}
129				continue;
130			}
131			if (boot_record_count == 1)
132				nftl->SpareMediaUnit = block;
133
134			/* Mark this boot record (NFTL MediaHeader) block as reserved */
135			nftl->ReplUnitTable[block] = BLOCK_RESERVED;
136
137
138			boot_record_count++;
139			continue;
140		}
141
142		/* This is the first we've seen. Copy the media header structure into place */
143		memcpy(mh, buf, sizeof(struct NFTLMediaHeader));
144
145		/* Do some sanity checks on it */
146#if 0
147The new DiskOnChip driver scans the MediaHeader itself, and presents a virtual
148erasesize based on UnitSizeFactor.  So the erasesize we read from the mtd
149device is already correct.
150		if (mh->UnitSizeFactor == 0) {
151			printk(KERN_NOTICE "NFTL: UnitSizeFactor 0x00 detected. This violates the spec but we think we know what it means...\n");
152		} else if (mh->UnitSizeFactor < 0xfc) {
153			printk(KERN_NOTICE "Sorry, we don't support UnitSizeFactor 0x%02x\n",
154			       mh->UnitSizeFactor);
155			return -1;
156		} else if (mh->UnitSizeFactor != 0xff) {
157			printk(KERN_NOTICE "WARNING: Support for NFTL with UnitSizeFactor 0x%02x is experimental\n",
158			       mh->UnitSizeFactor);
159			nftl->EraseSize = nftl->mbd.mtd->erasesize << (0xff - mh->UnitSizeFactor);
160			nftl->nb_blocks = (u32)nftl->mbd.mtd->size / nftl->EraseSize;
161		}
162#endif
163		nftl->nb_boot_blocks = le16_to_cpu(mh->FirstPhysicalEUN);
164		if ((nftl->nb_boot_blocks + 2) >= nftl->nb_blocks) {
165			printk(KERN_NOTICE "NFTL Media Header sanity check failed:\n");
166			printk(KERN_NOTICE "nb_boot_blocks (%d) + 2 > nb_blocks (%d)\n",
167			       nftl->nb_boot_blocks, nftl->nb_blocks);
168			return -1;
169		}
170
171		nftl->numvunits = le32_to_cpu(mh->FormattedSize) / nftl->EraseSize;
172		if (nftl->numvunits > (nftl->nb_blocks - nftl->nb_boot_blocks - 2)) {
173			printk(KERN_NOTICE "NFTL Media Header sanity check failed:\n");
174			printk(KERN_NOTICE "numvunits (%d) > nb_blocks (%d) - nb_boot_blocks(%d) - 2\n",
175			       nftl->numvunits, nftl->nb_blocks, nftl->nb_boot_blocks);
176			return -1;
177		}
178
179		nftl->mbd.size  = nftl->numvunits * (nftl->EraseSize / SECTORSIZE);
180
181		/* If we're not using the last sectors in the device for some reason,
182		   reduce nb_blocks accordingly so we forget they're there */
183		nftl->nb_blocks = le16_to_cpu(mh->NumEraseUnits) + le16_to_cpu(mh->FirstPhysicalEUN);
184
185		/* XXX: will be suppressed */
186		nftl->lastEUN = nftl->nb_blocks - 1;
187
188		/* memory alloc */
189		nftl->EUNtable = kmalloc_array(nftl->nb_blocks, sizeof(u16),
190					       GFP_KERNEL);
191		if (!nftl->EUNtable)
192			return -ENOMEM;
193
194		nftl->ReplUnitTable = kmalloc_array(nftl->nb_blocks,
195						    sizeof(u16),
196						    GFP_KERNEL);
197		if (!nftl->ReplUnitTable) {
198			kfree(nftl->EUNtable);
199			return -ENOMEM;
200		}
201
202		/* mark the bios blocks (blocks before NFTL MediaHeader) as reserved */
203		for (i = 0; i < nftl->nb_boot_blocks; i++)
204			nftl->ReplUnitTable[i] = BLOCK_RESERVED;
205		/* mark all remaining blocks as potentially containing data */
206		for (; i < nftl->nb_blocks; i++) {
207			nftl->ReplUnitTable[i] = BLOCK_NOTEXPLORED;
208		}
209
210		/* Mark this boot record (NFTL MediaHeader) block as reserved */
211		nftl->ReplUnitTable[block] = BLOCK_RESERVED;
212
213		/* read the Bad Erase Unit Table and modify ReplUnitTable[] accordingly */
214		for (i = 0; i < nftl->nb_blocks; i++) {
215#if 0
216The new DiskOnChip driver already scanned the bad block table.  Just query it.
217			if ((i & (SECTORSIZE - 1)) == 0) {
218				/* read one sector for every SECTORSIZE of blocks */
219				ret = mtd->read(nftl->mbd.mtd,
220						block * nftl->EraseSize + i +
221						SECTORSIZE, SECTORSIZE,
222						&retlen, buf);
223				if (ret < 0) {
224					printk(KERN_NOTICE "Read of bad sector table failed (err %d)\n",
225					       ret);
226					kfree(nftl->ReplUnitTable);
227					kfree(nftl->EUNtable);
228					return -1;
229				}
230			}
231			/* mark the Bad Erase Unit as RESERVED in ReplUnitTable */
232			if (buf[i & (SECTORSIZE - 1)] != 0xff)
233				nftl->ReplUnitTable[i] = BLOCK_RESERVED;
234#endif
235			if (mtd_block_isbad(nftl->mbd.mtd,
236					    i * nftl->EraseSize))
237				nftl->ReplUnitTable[i] = BLOCK_RESERVED;
238		}
239
240		nftl->MediaUnit = block;
241		boot_record_count++;
242
243	} /* foreach (block) */
244
245	return boot_record_count?0:-1;
246}
247
248static int memcmpb(void *a, int c, int n)
249{
250	int i;
251	for (i = 0; i < n; i++) {
252		if (c != ((unsigned char *)a)[i])
253			return 1;
254	}
255	return 0;
256}
257
258/* check_free_sector: check if a free sector is actually FREE, i.e. All 0xff in data and oob area */
259static int check_free_sectors(struct NFTLrecord *nftl, unsigned int address, int len,
260			      int check_oob)
261{
262	struct mtd_info *mtd = nftl->mbd.mtd;
263	size_t retlen;
264	int i, ret;
265	u8 *buf;
266
267	buf = kmalloc(SECTORSIZE + mtd->oobsize, GFP_KERNEL);
268	if (!buf)
269		return -ENOMEM;
270
271	ret = -1;
272	for (i = 0; i < len; i += SECTORSIZE) {
273		if (mtd_read(mtd, address, SECTORSIZE, &retlen, buf))
274			goto out;
275		if (memcmpb(buf, 0xff, SECTORSIZE) != 0)
276			goto out;
277
278		if (check_oob) {
279			if(nftl_read_oob(mtd, address, mtd->oobsize,
280					 &retlen, &buf[SECTORSIZE]) < 0)
281				goto out;
282			if (memcmpb(buf + SECTORSIZE, 0xff, mtd->oobsize) != 0)
283				goto out;
284		}
285		address += SECTORSIZE;
286	}
287
288	ret = 0;
289
290out:
291	kfree(buf);
292	return ret;
293}
294
295/* NFTL_format: format a Erase Unit by erasing ALL Erase Zones in the Erase Unit and
296 *              Update NFTL metadata. Each erase operation is checked with check_free_sectors
297 *
298 * Return: 0 when succeed, -1 on error.
299 *
300 *  ToDo: 1. Is it necessary to check_free_sector after erasing ??
301 */
302int NFTL_formatblock(struct NFTLrecord *nftl, int block)
303{
304	size_t retlen;
305	unsigned int nb_erases, erase_mark;
306	struct nftl_uci1 uci;
307	struct erase_info *instr = &nftl->instr;
308	struct mtd_info *mtd = nftl->mbd.mtd;
309
310	/* Read the Unit Control Information #1 for Wear-Leveling */
311	if (nftl_read_oob(mtd, block * nftl->EraseSize + SECTORSIZE + 8,
312			  8, &retlen, (char *)&uci) < 0)
313		goto default_uci1;
314
315	erase_mark = le16_to_cpu ((uci.EraseMark | uci.EraseMark1));
316	if (erase_mark != ERASE_MARK) {
317	default_uci1:
318		uci.EraseMark = cpu_to_le16(ERASE_MARK);
319		uci.EraseMark1 = cpu_to_le16(ERASE_MARK);
320		uci.WearInfo = cpu_to_le32(0);
321	}
322
323	memset(instr, 0, sizeof(struct erase_info));
324
325	/* XXX: use async erase interface, XXX: test return code */
326	instr->addr = block * nftl->EraseSize;
327	instr->len = nftl->EraseSize;
328	if (mtd_erase(mtd, instr)) {
329		printk("Error while formatting block %d\n", block);
330		goto fail;
331	}
332
333	/* increase and write Wear-Leveling info */
334	nb_erases = le32_to_cpu(uci.WearInfo);
335	nb_erases++;
336
337	/* wrap (almost impossible with current flash) or free block */
338	if (nb_erases == 0)
339		nb_erases = 1;
340
341	/* check the "freeness" of Erase Unit before updating metadata
342	 * FixMe:  is this check really necessary ? since we have check the
343	 *         return code after the erase operation.
344	 */
345	if (check_free_sectors(nftl, instr->addr, nftl->EraseSize, 1) != 0)
346		goto fail;
347
348	uci.WearInfo = le32_to_cpu(nb_erases);
349	if (nftl_write_oob(mtd, block * nftl->EraseSize + SECTORSIZE +
350			   8, 8, &retlen, (char *)&uci) < 0)
351		goto fail;
352	return 0;
353fail:
354	/* could not format, update the bad block table (caller is responsible
355	   for setting the ReplUnitTable to BLOCK_RESERVED on failure) */
356	mtd_block_markbad(nftl->mbd.mtd, instr->addr);
357	return -1;
358}
359
360/* check_sectors_in_chain: Check that each sector of a Virtual Unit Chain is correct.
361 *	Mark as 'IGNORE' each incorrect sector. This check is only done if the chain
362 *	was being folded when NFTL was interrupted.
363 *
364 *	The check_free_sectors in this function is necessary. There is a possible
365 *	situation that after writing the Data area, the Block Control Information is
366 *	not updated according (due to power failure or something) which leaves the block
367 *	in an inconsistent state. So we have to check if a block is really FREE in this
368 *	case. */
369static void check_sectors_in_chain(struct NFTLrecord *nftl, unsigned int first_block)
370{
371	struct mtd_info *mtd = nftl->mbd.mtd;
372	unsigned int block, i, status;
373	struct nftl_bci bci;
374	int sectors_per_block;
375	size_t retlen;
376
377	sectors_per_block = nftl->EraseSize / SECTORSIZE;
378	block = first_block;
379	for (;;) {
380		for (i = 0; i < sectors_per_block; i++) {
381			if (nftl_read_oob(mtd,
382					  block * nftl->EraseSize + i * SECTORSIZE,
383					  8, &retlen, (char *)&bci) < 0)
384				status = SECTOR_IGNORE;
385			else
386				status = bci.Status | bci.Status1;
387
388			switch(status) {
389			case SECTOR_FREE:
390				/* verify that the sector is really free. If not, mark
391				   as ignore */
392				if (memcmpb(&bci, 0xff, 8) != 0 ||
393				    check_free_sectors(nftl, block * nftl->EraseSize + i * SECTORSIZE,
394						       SECTORSIZE, 0) != 0) {
395					printk("Incorrect free sector %d in block %d: "
396					       "marking it as ignored\n",
397					       i, block);
398
399					/* sector not free actually : mark it as SECTOR_IGNORE  */
400					bci.Status = SECTOR_IGNORE;
401					bci.Status1 = SECTOR_IGNORE;
402					nftl_write_oob(mtd, block *
403						       nftl->EraseSize +
404						       i * SECTORSIZE, 8,
405						       &retlen, (char *)&bci);
406				}
407				break;
408			default:
409				break;
410			}
411		}
412
413		/* proceed to next Erase Unit on the chain */
414		block = nftl->ReplUnitTable[block];
415		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
416			printk("incorrect ReplUnitTable[] : %d\n", block);
417		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
418			break;
419	}
420}
421
422/* calc_chain_length: Walk through a Virtual Unit Chain and estimate chain length */
423static int calc_chain_length(struct NFTLrecord *nftl, unsigned int first_block)
424{
425	unsigned int length = 0, block = first_block;
426
427	for (;;) {
428		length++;
429		/* avoid infinite loops, although this is guaranteed not to
430		   happen because of the previous checks */
431		if (length >= nftl->nb_blocks) {
432			printk("nftl: length too long %d !\n", length);
433			break;
434		}
435
436		block = nftl->ReplUnitTable[block];
437		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
438			printk("incorrect ReplUnitTable[] : %d\n", block);
439		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
440			break;
441	}
442	return length;
443}
444
445/* format_chain: Format an invalid Virtual Unit chain. It frees all the Erase Units in a
446 *	Virtual Unit Chain, i.e. all the units are disconnected.
447 *
448 *	It is not strictly correct to begin from the first block of the chain because
449 *	if we stop the code, we may see again a valid chain if there was a first_block
450 *	flag in a block inside it. But is it really a problem ?
451 *
452 * FixMe: Figure out what the last statement means. What if power failure when we are
453 *	in the for (;;) loop formatting blocks ??
454 */
455static void format_chain(struct NFTLrecord *nftl, unsigned int first_block)
456{
457	unsigned int block = first_block, block1;
458
459	printk("Formatting chain at block %d\n", first_block);
460
461	for (;;) {
462		block1 = nftl->ReplUnitTable[block];
463
464		printk("Formatting block %d\n", block);
465		if (NFTL_formatblock(nftl, block) < 0) {
466			/* cannot format !!!! Mark it as Bad Unit */
467			nftl->ReplUnitTable[block] = BLOCK_RESERVED;
468		} else {
469			nftl->ReplUnitTable[block] = BLOCK_FREE;
470		}
471
472		/* goto next block on the chain */
473		block = block1;
474
475		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
476			printk("incorrect ReplUnitTable[] : %d\n", block);
477		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
478			break;
479	}
480}
481
482/* check_and_mark_free_block: Verify that a block is free in the NFTL sense (valid erase mark) or
483 *	totally free (only 0xff).
484 *
485 * Definition: Free Erase Unit -- A properly erased/formatted Free Erase Unit should have meet the
486 *	following criteria:
487 *	1. */
488static int check_and_mark_free_block(struct NFTLrecord *nftl, int block)
489{
490	struct mtd_info *mtd = nftl->mbd.mtd;
491	struct nftl_uci1 h1;
492	unsigned int erase_mark;
493	size_t retlen;
494
495	/* check erase mark. */
496	if (nftl_read_oob(mtd, block * nftl->EraseSize + SECTORSIZE + 8, 8,
497			  &retlen, (char *)&h1) < 0)
498		return -1;
499
500	erase_mark = le16_to_cpu ((h1.EraseMark | h1.EraseMark1));
501	if (erase_mark != ERASE_MARK) {
502		/* if no erase mark, the block must be totally free. This is
503		   possible in two cases : empty filesystem or interrupted erase (very unlikely) */
504		if (check_free_sectors (nftl, block * nftl->EraseSize, nftl->EraseSize, 1) != 0)
505			return -1;
506
507		/* free block : write erase mark */
508		h1.EraseMark = cpu_to_le16(ERASE_MARK);
509		h1.EraseMark1 = cpu_to_le16(ERASE_MARK);
510		h1.WearInfo = cpu_to_le32(0);
511		if (nftl_write_oob(mtd,
512				   block * nftl->EraseSize + SECTORSIZE + 8, 8,
513				   &retlen, (char *)&h1) < 0)
514			return -1;
515	} else {
516#if 0
517		/* if erase mark present, need to skip it when doing check */
518		for (i = 0; i < nftl->EraseSize; i += SECTORSIZE) {
519			/* check free sector */
520			if (check_free_sectors (nftl, block * nftl->EraseSize + i,
521						SECTORSIZE, 0) != 0)
522				return -1;
523
524			if (nftl_read_oob(mtd, block * nftl->EraseSize + i,
525					  16, &retlen, buf) < 0)
526				return -1;
527			if (i == SECTORSIZE) {
528				/* skip erase mark */
529				if (memcmpb(buf, 0xff, 8))
530					return -1;
531			} else {
532				if (memcmpb(buf, 0xff, 16))
533					return -1;
534			}
535		}
536#endif
537	}
538
539	return 0;
540}
541
542/* get_fold_mark: Read fold mark from Unit Control Information #2, we use FOLD_MARK_IN_PROGRESS
543 *	to indicate that we are in the progression of a Virtual Unit Chain folding. If the UCI #2
544 *	is FOLD_MARK_IN_PROGRESS when mounting the NFTL, the (previous) folding process is interrupted
545 *	for some reason. A clean up/check of the VUC is necessary in this case.
546 *
547 * WARNING: return 0 if read error
548 */
549static int get_fold_mark(struct NFTLrecord *nftl, unsigned int block)
550{
551	struct mtd_info *mtd = nftl->mbd.mtd;
552	struct nftl_uci2 uci;
553	size_t retlen;
554
555	if (nftl_read_oob(mtd, block * nftl->EraseSize + 2 * SECTORSIZE + 8,
556			  8, &retlen, (char *)&uci) < 0)
557		return 0;
558
559	return le16_to_cpu((uci.FoldMark | uci.FoldMark1));
560}
561
562int NFTL_mount(struct NFTLrecord *s)
563{
564	int i;
565	unsigned int first_logical_block, logical_block, rep_block, erase_mark;
566	unsigned int block, first_block, is_first_block;
567	int chain_length, do_format_chain;
568	struct nftl_uci0 h0;
569	struct nftl_uci1 h1;
570	struct mtd_info *mtd = s->mbd.mtd;
571	size_t retlen;
572
573	/* search for NFTL MediaHeader and Spare NFTL Media Header */
574	if (find_boot_record(s) < 0) {
575		printk("Could not find valid boot record\n");
576		return -1;
577	}
578
579	/* init the logical to physical table */
580	for (i = 0; i < s->nb_blocks; i++) {
581		s->EUNtable[i] = BLOCK_NIL;
582	}
583
584	/* first pass : explore each block chain */
585	first_logical_block = 0;
586	for (first_block = 0; first_block < s->nb_blocks; first_block++) {
587		/* if the block was not already explored, we can look at it */
588		if (s->ReplUnitTable[first_block] == BLOCK_NOTEXPLORED) {
589			block = first_block;
590			chain_length = 0;
591			do_format_chain = 0;
592
593			for (;;) {
594				/* read the block header. If error, we format the chain */
595				if (nftl_read_oob(mtd,
596						  block * s->EraseSize + 8, 8,
597						  &retlen, (char *)&h0) < 0 ||
598				    nftl_read_oob(mtd,
599						  block * s->EraseSize +
600						  SECTORSIZE + 8, 8,
601						  &retlen, (char *)&h1) < 0) {
602					s->ReplUnitTable[block] = BLOCK_NIL;
603					do_format_chain = 1;
604					break;
605				}
606
607				logical_block = le16_to_cpu ((h0.VirtUnitNum | h0.SpareVirtUnitNum));
608				rep_block = le16_to_cpu ((h0.ReplUnitNum | h0.SpareReplUnitNum));
609				erase_mark = le16_to_cpu ((h1.EraseMark | h1.EraseMark1));
610
611				is_first_block = !(logical_block >> 15);
612				logical_block = logical_block & 0x7fff;
613
614				/* invalid/free block test */
615				if (erase_mark != ERASE_MARK || logical_block >= s->nb_blocks) {
616					if (chain_length == 0) {
617						/* if not currently in a chain, we can handle it safely */
618						if (check_and_mark_free_block(s, block) < 0) {
619							/* not really free: format it */
620							printk("Formatting block %d\n", block);
621							if (NFTL_formatblock(s, block) < 0) {
622								/* could not format: reserve the block */
623								s->ReplUnitTable[block] = BLOCK_RESERVED;
624							} else {
625								s->ReplUnitTable[block] = BLOCK_FREE;
626							}
627						} else {
628							/* free block: mark it */
629							s->ReplUnitTable[block] = BLOCK_FREE;
630						}
631						/* directly examine the next block. */
632						goto examine_ReplUnitTable;
633					} else {
634						/* the block was in a chain : this is bad. We
635						   must format all the chain */
636						printk("Block %d: free but referenced in chain %d\n",
637						       block, first_block);
638						s->ReplUnitTable[block] = BLOCK_NIL;
639						do_format_chain = 1;
640						break;
641					}
642				}
643
644				/* we accept only first blocks here */
645				if (chain_length == 0) {
646					/* this block is not the first block in chain :
647					   ignore it, it will be included in a chain
648					   later, or marked as not explored */
649					if (!is_first_block)
650						goto examine_ReplUnitTable;
651					first_logical_block = logical_block;
652				} else {
653					if (logical_block != first_logical_block) {
654						printk("Block %d: incorrect logical block: %d expected: %d\n",
655						       block, logical_block, first_logical_block);
656						/* the chain is incorrect : we must format it,
657						   but we need to read it completely */
658						do_format_chain = 1;
659					}
660					if (is_first_block) {
661						/* we accept that a block is marked as first
662						   block while being last block in a chain
663						   only if the chain is being folded */
664						if (get_fold_mark(s, block) != FOLD_MARK_IN_PROGRESS ||
665						    rep_block != 0xffff) {
666							printk("Block %d: incorrectly marked as first block in chain\n",
667							       block);
668							/* the chain is incorrect : we must format it,
669							   but we need to read it completely */
670							do_format_chain = 1;
671						} else {
672							printk("Block %d: folding in progress - ignoring first block flag\n",
673							       block);
674						}
675					}
676				}
677				chain_length++;
678				if (rep_block == 0xffff) {
679					/* no more blocks after */
680					s->ReplUnitTable[block] = BLOCK_NIL;
681					break;
682				} else if (rep_block >= s->nb_blocks) {
683					printk("Block %d: referencing invalid block %d\n",
684					       block, rep_block);
685					do_format_chain = 1;
686					s->ReplUnitTable[block] = BLOCK_NIL;
687					break;
688				} else if (s->ReplUnitTable[rep_block] != BLOCK_NOTEXPLORED) {
689					/* same problem as previous 'is_first_block' test:
690					   we accept that the last block of a chain has
691					   the first_block flag set if folding is in
692					   progress. We handle here the case where the
693					   last block appeared first */
694					if (s->ReplUnitTable[rep_block] == BLOCK_NIL &&
695					    s->EUNtable[first_logical_block] == rep_block &&
696					    get_fold_mark(s, first_block) == FOLD_MARK_IN_PROGRESS) {
697						/* EUNtable[] will be set after */
698						printk("Block %d: folding in progress - ignoring first block flag\n",
699						       rep_block);
700						s->ReplUnitTable[block] = rep_block;
701						s->EUNtable[first_logical_block] = BLOCK_NIL;
702					} else {
703						printk("Block %d: referencing block %d already in another chain\n",
704						       block, rep_block);
705						/* XXX: should handle correctly fold in progress chains */
706						do_format_chain = 1;
707						s->ReplUnitTable[block] = BLOCK_NIL;
708					}
709					break;
710				} else {
711					/* this is OK */
712					s->ReplUnitTable[block] = rep_block;
713					block = rep_block;
714				}
715			}
716
717			/* the chain was completely explored. Now we can decide
718			   what to do with it */
719			if (do_format_chain) {
720				/* invalid chain : format it */
721				format_chain(s, first_block);
722			} else {
723				unsigned int first_block1, chain_to_format, chain_length1;
724				int fold_mark;
725
726				/* valid chain : get foldmark */
727				fold_mark = get_fold_mark(s, first_block);
728				if (fold_mark == 0) {
729					/* cannot get foldmark : format the chain */
730					printk("Could read foldmark at block %d\n", first_block);
731					format_chain(s, first_block);
732				} else {
733					if (fold_mark == FOLD_MARK_IN_PROGRESS)
734						check_sectors_in_chain(s, first_block);
735
736					/* now handle the case where we find two chains at the
737					   same virtual address : we select the longer one,
738					   because the shorter one is the one which was being
739					   folded if the folding was not done in place */
740					first_block1 = s->EUNtable[first_logical_block];
741					if (first_block1 != BLOCK_NIL) {
742						/* XXX: what to do if same length ? */
743						chain_length1 = calc_chain_length(s, first_block1);
744						printk("Two chains at blocks %d (len=%d) and %d (len=%d)\n",
745						       first_block1, chain_length1, first_block, chain_length);
746
747						if (chain_length >= chain_length1) {
748							chain_to_format = first_block1;
749							s->EUNtable[first_logical_block] = first_block;
750						} else {
751							chain_to_format = first_block;
752						}
753						format_chain(s, chain_to_format);
754					} else {
755						s->EUNtable[first_logical_block] = first_block;
756					}
757				}
758			}
759		}
760	examine_ReplUnitTable:;
761	}
762
763	/* second pass to format unreferenced blocks  and init free block count */
764	s->numfreeEUNs = 0;
765	s->LastFreeEUN = le16_to_cpu(s->MediaHdr.FirstPhysicalEUN);
766
767	for (block = 0; block < s->nb_blocks; block++) {
768		if (s->ReplUnitTable[block] == BLOCK_NOTEXPLORED) {
769			printk("Unreferenced block %d, formatting it\n", block);
770			if (NFTL_formatblock(s, block) < 0)
771				s->ReplUnitTable[block] = BLOCK_RESERVED;
772			else
773				s->ReplUnitTable[block] = BLOCK_FREE;
774		}
775		if (s->ReplUnitTable[block] == BLOCK_FREE) {
776			s->numfreeEUNs++;
777			s->LastFreeEUN = block;
778		}
779	}
780
781	return 0;
782}
783