scan.c

jffs2源代码基于2。6内核

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <[e-mail]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: scan.c,v 1.112 2004/09/12 09:56:13 gleixner Exp $
 *
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/pagemap.h>
#include <linux/crc32.h>
#include <linux/compiler.h>
#include "nodelist.h"

#define EMPTY_SCAN_SIZE 1024

#define DIRTY_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->dirty_size += _x; \
		jeb->free_size -= _x ; jeb->dirty_size += _x; \
		}while(0)
#define USED_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->used_size += _x; \
		jeb->free_size -= _x ; jeb->used_size += _x; \
		}while(0)
#define UNCHECKED_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->unchecked_size += _x; \
		jeb->free_size -= _x ; jeb->unchecked_size += _x; \
		}while(0)

#define noisy_printk(noise, args...) do { \
	if (*(noise)) { \
		printk(KERN_NOTICE args); \
		 (*(noise))--; \
		 if (!(*(noise))) { \
			 printk(KERN_NOTICE "Further such events for this erase block will not be printed\n"); \
		 } \
	} \
} while(0)

static uint32_t pseudo_random;

static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				  unsigned char *buf, uint32_t buf_size);

/* These helper functions _must_ increase ofs and also do the dirty/used space accounting. 
 * Returning an error will abort the mount - bad checksums etc. should just mark the space
 * as dirty.
 */
static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
				 struct jffs2_raw_inode *ri, uint32_t ofs);
static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				 struct jffs2_raw_dirent *rd, uint32_t ofs);

#define BLK_STATE_ALLFF		0
#define BLK_STATE_CLEAN		1
#define BLK_STATE_PARTDIRTY	2
#define BLK_STATE_CLEANMARKER	3
#define BLK_STATE_ALLDIRTY	4
#define BLK_STATE_BADBLOCK	5

static inline int min_free(struct jffs2_sb_info *c)
{
	uint32_t min = 2 * sizeof(struct jffs2_raw_inode);
#ifdef CONFIG_JFFS2_FS_NAND
	if (!jffs2_can_mark_obsolete(c) && min < c->wbuf_pagesize)
		return c->wbuf_pagesize;
#endif
	return min;

}
int jffs2_scan_medium(struct jffs2_sb_info *c)
{
	int i, ret;
	uint32_t empty_blocks = 0, bad_blocks = 0;
	unsigned char *flashbuf = NULL;
	uint32_t buf_size = 0;
#ifndef __ECOS
	size_t pointlen;

	if (c->mtd->point) {
		ret = c->mtd->point (c->mtd, 0, c->mtd->size, &pointlen, &flashbuf);
		if (!ret && pointlen < c->mtd->size) {
			/* Don't muck about if it won't let us point to the whole flash */
			D1(printk(KERN_DEBUG "MTD point returned len too short: 0x%zx\n", pointlen));
			c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
			flashbuf = NULL;
		}
		if (ret)
			D1(printk(KERN_DEBUG "MTD point failed %d\n", ret));
	}
#endif
	if (!flashbuf) {
		/* For NAND it's quicker to read a whole eraseblock at a time,
		   apparently */
		if (jffs2_cleanmarker_oob(c))
			buf_size = c->sector_size;
		else
			buf_size = PAGE_SIZE;

		/* Respect kmalloc limitations */
		if (buf_size > 128*1024)
			buf_size = 128*1024;

		D1(printk(KERN_DEBUG "Allocating readbuf of %d bytes\n", buf_size));
		flashbuf = kmalloc(buf_size, GFP_KERNEL);
		if (!flashbuf)
			return -ENOMEM;
	}

	for (i=0; i<c->nr_blocks; i++) {
		struct jffs2_eraseblock *jeb = &c->blocks[i];

		ret = jffs2_scan_eraseblock(c, jeb, buf_size?flashbuf:(flashbuf+jeb->offset), buf_size);

		if (ret < 0)
			goto out;

		ACCT_PARANOIA_CHECK(jeb);

		/* Now decide which list to put it on */
		switch(ret) {
		case BLK_STATE_ALLFF:
			/* 
			 * Empty block.   Since we can't be sure it 
			 * was entirely erased, we just queue it for erase
			 * again.  It will be marked as such when the erase
			 * is complete.  Meanwhile we still count it as empty
			 * for later checks.
			 */
			empty_blocks++;
			list_add(&jeb->list, &c->erase_pending_list);
			c->nr_erasing_blocks++;
			break;

		case BLK_STATE_CLEANMARKER:
			/* Only a CLEANMARKER node is valid */
			if (!jeb->dirty_size) {
				/* It's actually free */
				list_add(&jeb->list, &c->free_list);
				c->nr_free_blocks++;
			} else {
				/* Dirt */
				D1(printk(KERN_DEBUG "Adding all-dirty block at 0x%08x to erase_pending_list\n", jeb->offset));
				list_add(&jeb->list, &c->erase_pending_list);
				c->nr_erasing_blocks++;
			}
			break;

		case BLK_STATE_CLEAN:
                        /* Full (or almost full) of clean data. Clean list */
                        list_add(&jeb->list, &c->clean_list);
			break;

		case BLK_STATE_PARTDIRTY:
                        /* Some data, but not full. Dirty list. */
                        /* Except that we want to remember the block with most free space,
                           and stick it in the 'nextblock' position to start writing to it.
                           Later when we do snapshots, this must be the most recent block,
                           not the one with most free space.
                        */
                        if (jeb->free_size > min_free(c) && 
			    (!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
                                /* Better candidate for the next writes to go to */
                                if (c->nextblock) {
					c->nextblock->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
					c->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
					c->free_size -= c->nextblock->free_size;
					c->wasted_size -= c->nextblock->wasted_size;
					c->nextblock->free_size = c->nextblock->wasted_size = 0;
					if (VERYDIRTY(c, c->nextblock->dirty_size)) {
						list_add(&c->nextblock->list, &c->very_dirty_list);
					} else {
						list_add(&c->nextblock->list, &c->dirty_list);
					}
				}
                                c->nextblock = jeb;
                        } else {
				jeb->dirty_size += jeb->free_size + jeb->wasted_size;
				c->dirty_size += jeb->free_size + jeb->wasted_size;
				c->free_size -= jeb->free_size;
				c->wasted_size -= jeb->wasted_size;
				jeb->free_size = jeb->wasted_size = 0;
				if (VERYDIRTY(c, jeb->dirty_size)) {
					list_add(&jeb->list, &c->very_dirty_list);
				} else {
					list_add(&jeb->list, &c->dirty_list);
				}
                        }
			break;

		case BLK_STATE_ALLDIRTY:
			/* Nothing valid - not even a clean marker. Needs erasing. */
                        /* For now we just put it on the erasing list. We'll start the erases later */
			D1(printk(KERN_NOTICE "JFFS2: Erase block at 0x%08x is not formatted. It will be erased\n", jeb->offset));
                        list_add(&jeb->list, &c->erase_pending_list);
			c->nr_erasing_blocks++;
			break;
			
		case BLK_STATE_BADBLOCK:
			D1(printk(KERN_NOTICE "JFFS2: Block at 0x%08x is bad\n", jeb->offset));
                        list_add(&jeb->list, &c->bad_list);
			c->bad_size += c->sector_size;
			c->free_size -= c->sector_size;
			bad_blocks++;
			break;
		default:
			printk(KERN_WARNING "jffs2_scan_medium(): unknown block state\n");
			BUG();	
		}
	}
	
	/* Nextblock dirty is always seen as wasted, because we cannot recycle it now */
	if (c->nextblock && (c->nextblock->dirty_size)) {
		c->nextblock->wasted_size += c->nextblock->dirty_size;
		c->wasted_size += c->nextblock->dirty_size;
		c->dirty_size -= c->nextblock->dirty_size;
		c->nextblock->dirty_size = 0;
	}
#ifdef CONFIG_JFFS2_FS_NAND
	if (!jffs2_can_mark_obsolete(c) && c->nextblock && (c->nextblock->free_size & (c->wbuf_pagesize-1))) {
		/* If we're going to start writing into a block which already 
		   contains data, and the end of the data isn't page-aligned,
		   skip a little and align it. */

		uint32_t skip = c->nextblock->free_size & (c->wbuf_pagesize-1);

		D1(printk(KERN_DEBUG "jffs2_scan_medium(): Skipping %d bytes in nextblock to ensure page alignment\n",
			  skip));
		c->nextblock->wasted_size += skip;
		c->wasted_size += skip;

		c->nextblock->free_size -= skip;
		c->free_size -= skip;
	}
#endif
	if (c->nr_erasing_blocks) {
		if ( !c->used_size && ((c->nr_free_blocks+empty_blocks+bad_blocks)!= c->nr_blocks || bad_blocks == c->nr_blocks) ) { 
			printk(KERN_NOTICE "Cowardly refusing to erase blocks on filesystem with no valid JFFS2 nodes\n");
			printk(KERN_NOTICE "empty_blocks %d, bad_blocks %d, c->nr_blocks %d\n",empty_blocks,bad_blocks,c->nr_blocks);
			ret = -EIO;
			goto out;
		}
		jffs2_erase_pending_trigger(c);
	}
	ret = 0;
 out:
	if (buf_size)
		kfree(flashbuf);
#ifndef __ECOS
	else 
		c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
#endif
	return ret;
}

static int jffs2_fill_scan_buf (struct jffs2_sb_info *c, unsigned char *buf,
				uint32_t ofs, uint32_t len)
{
	int ret;
	size_t retlen;

	ret = jffs2_flash_read(c, ofs, len, &retlen, buf);
	if (ret) {
		D1(printk(KERN_WARNING "mtd->read(0x%x bytes from 0x%x) returned %d\n", len, ofs, ret));
		return ret;
	}
	if (retlen < len) {
		D1(printk(KERN_WARNING "Read at 0x%x gave only 0x%zx bytes\n", ofs, retlen));
		return -EIO;
	}
	D2(printk(KERN_DEBUG "Read 0x%x bytes from 0x%08x into buf\n", len, ofs));
	D2(printk(KERN_DEBUG "000: %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x\n",
		  buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12], buf[13], buf[14], buf[15]));
	return 0;
}

static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				  unsigned char *buf, uint32_t buf_size) {
	struct jffs2_unknown_node *node;
	struct jffs2_unknown_node crcnode;
	uint32_t ofs, prevofs;
	uint32_t hdr_crc, buf_ofs, buf_len;
	int err;
	int noise = 0;
#ifdef CONFIG_JFFS2_FS_NAND
	int cleanmarkerfound = 0;
#endif

	ofs = jeb->offset;
	prevofs = jeb->offset - 1;

	D1(printk(KERN_DEBUG "jffs2_scan_eraseblock(): Scanning block at 0x%x\n", ofs));

#ifdef CONFIG_JFFS2_FS_NAND
	if (jffs2_cleanmarker_oob(c)) {
		int ret = jffs2_check_nand_cleanmarker(c, jeb);
		D2(printk(KERN_NOTICE "jffs_check_nand_cleanmarker returned %d\n",ret));
		/* Even if it's not found, we still scan to see
		   if the block is empty. We use this information
		   to decide whether to erase it or not. */
		switch (ret) {
		case 0:		cleanmarkerfound = 1; break;
		case 1: 	break;
		case 2: 	return BLK_STATE_BADBLOCK;
		case 3:		return BLK_STATE_ALLDIRTY; /* Block has failed to erase min. once */
		default: 	return ret;
		}
	}
#endif
	buf_ofs = jeb->offset;

	if (!buf_size) {
		buf_len = c->sector_size;
	} else {
		buf_len = EMPTY_SCAN_SIZE;
		err = jffs2_fill_scan_buf(c, buf, buf_ofs, buf_len);
		if (err)
			return err;
	}
	
	/* We temporarily use 'ofs' as a pointer into the buffer/jeb */
	ofs = 0;

	/* Scan only 4KiB of 0xFF before declaring it's empty */
	while(ofs < EMPTY_SCAN_SIZE && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
		ofs += 4;

	if (ofs == EMPTY_SCAN_SIZE) {
#ifdef CONFIG_JFFS2_FS_NAND
		if (jffs2_cleanmarker_oob(c)) {
			/* scan oob, take care of cleanmarker */
			int ret = jffs2_check_oob_empty(c, jeb, cleanmarkerfound);
			D2(printk(KERN_NOTICE "jffs2_check_oob_empty returned %d\n",ret));
			switch (ret) {
			case 0:		return cleanmarkerfound ? BLK_STATE_CLEANMARKER : BLK_STATE_ALLFF;
			case 1: 	return BLK_STATE_ALLDIRTY;
			default: 	return ret;
			}
		}
#endif
		D1(printk(KERN_DEBUG "Block at 0x%08x is empty (erased)\n", jeb->offset));
		return BLK_STATE_ALLFF;	/* OK to erase if all blocks are like this */
	}
	if (ofs) {
		D1(printk(KERN_DEBUG "Free space at %08x ends at %08x\n", jeb->offset,
			  jeb->offset + ofs));
		DIRTY_SPACE(ofs);
	}

	/* Now ofs is a complete physical flash offset as it always was... */
	ofs += jeb->offset;

	noise = 10;

scan_more:	
	while(ofs < jeb->offset + c->sector_size) {

		D1(ACCT_PARANOIA_CHECK(jeb));

		cond_resched();

		if (ofs & 3) {
			printk(KERN_WARNING "Eep. ofs 0x%08x not word-aligned!\n", ofs);
			ofs = PAD(ofs);
			continue;
		}
		if (ofs == prevofs) {
			printk(KERN_WARNING "ofs 0x%08x has already been seen. Skipping\n", ofs);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		prevofs = ofs;

		if (jeb->offset + c->sector_size < ofs + sizeof(*node)) {
			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),
				  jeb->offset, c->sector_size, ofs, sizeof(*node)));
			DIRTY_SPACE((jeb->offset + c->sector_size)-ofs);
			break;
		}

		if (buf_ofs + buf_len < ofs + sizeof(*node)) {
			buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
			D1(printk(KERN_DEBUG "Fewer than %zd bytes (node header) left to end of buf. Reading 0x%x at 0x%08x\n",
				  sizeof(struct jffs2_unknown_node), buf_len, ofs));
			err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
			if (err)
				return err;
			buf_ofs = ofs;
		}

		node = (struct jffs2_unknown_node *)&buf[ofs-buf_ofs];

		if (*(uint32_t *)(&buf[ofs-buf_ofs]) == 0xffffffff) {
			uint32_t inbuf_ofs;
			uint32_t empty_start;

			empty_start = ofs;
			ofs += 4;

			D1(printk(KERN_DEBUG "Found empty flash at 0x%08x\n", ofs));
		more_empty:
			inbuf_ofs = ofs - buf_ofs;
			while (inbuf_ofs < buf_len) {
				if (*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff) {
					printk(KERN_WARNING "Empty flash at 0x%08x ends at 0x%08x\n",
					       empty_start, ofs);
					DIRTY_SPACE(ofs-empty_start);
					goto scan_more;
				}

				inbuf_ofs+=4;
				ofs += 4;
			}
			/* Ran off end. */
			D1(printk(KERN_DEBUG "Empty flash to end of buffer at 0x%08x\n", ofs));

			/* If we're only checking the beginning of a block with a cleanmarker,
			   bail now */
			if (buf_ofs == jeb->offset && jeb->used_size == PAD(c->cleanmarker_size) && 
			    c->cleanmarker_size && !jeb->dirty_size && !jeb->first_node->next_in_ino) {
				D1(printk(KERN_DEBUG "%d bytes at start of block seems clean... assuming all clean\n", EMPTY_SCAN_SIZE));
				return BLK_STATE_CLEANMARKER;
			}

			/* See how much more there is to read in this eraseblock... */
			buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
			if (!buf_len) {
				/* No more to read. Break out of main loop without marking 
				   this range of empty space as dirty (because it's not) */
				D1(printk(KERN_DEBUG "Empty flash at %08x runs to end of block. Treating as free_space\n",
					  empty_start));
				break;
			}
			D1(printk(KERN_DEBUG "Reading another 0x%x at 0x%08x\n", buf_len, ofs));
			err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
			if (err)
				return err;
			buf_ofs = ofs;
			goto more_empty;
		}

		if (ofs == jeb->offset && je16_to_cpu(node->magic) == KSAMTIB_CIGAM_2SFFJ) {
			printk(KERN_WARNING "Magic bitmask is backwards at offset 0x%08x. Wrong endian filesystem?\n", ofs);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) == JFFS2_DIRTY_BITMASK) {
			D1(printk(KERN_DEBUG "Dirty bitmask at 0x%08x\n", ofs));
			DIRTY_SPACE(4);
			ofs += 4;
			continue;