scan.c

linux 内核源代码

	if (crc != je32_to_cpu(rr->node_crc)) {
		JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
			      ofs, je32_to_cpu(rr->node_crc), crc);
		if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(rr->totlen)))))
			return err;
		return 0;
	}

	if (PAD(sizeof(struct jffs2_raw_xref)) != je32_to_cpu(rr->totlen)) {
		JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%zd\n",
			      ofs, je32_to_cpu(rr->totlen),
			      PAD(sizeof(struct jffs2_raw_xref)));
		if ((err = jffs2_scan_dirty_space(c, jeb, je32_to_cpu(rr->totlen))))
			return err;
		return 0;
	}

	ref = jffs2_alloc_xattr_ref();
	if (!ref)
		return -ENOMEM;

	/* BEFORE jffs2_build_xattr_subsystem() called, 
	 * and AFTER xattr_ref is marked as a dead xref,
	 * ref->xid is used to store 32bit xid, xd is not used
	 * ref->ino is used to store 32bit inode-number, ic is not used
	 * Thoes variables are declared as union, thus using those
	 * are exclusive. In a similar way, ref->next is temporarily
	 * used to chain all xattr_ref object. It's re-chained to
	 * jffs2_inode_cache in jffs2_build_xattr_subsystem() correctly.
	 */
	ref->ino = je32_to_cpu(rr->ino);
	ref->xid = je32_to_cpu(rr->xid);
	ref->xseqno = je32_to_cpu(rr->xseqno);
	if (ref->xseqno > c->highest_xseqno)
		c->highest_xseqno = (ref->xseqno & ~XREF_DELETE_MARKER);
	ref->next = c->xref_temp;
	c->xref_temp = ref;

	jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, PAD(je32_to_cpu(rr->totlen)), (void *)ref);

	if (jffs2_sum_active())
		jffs2_sum_add_xref_mem(s, rr, ofs - jeb->offset);
	dbg_xattr("scan xref at %#08x (xid=%u, ino=%u)\n",
		  ofs, ref->xid, ref->ino);
	return 0;
}
#endif

/* Called with 'buf_size == 0' if buf is in fact a pointer _directly_ into
   the flash, XIP-style */
static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				  unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
	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_WRITEBUFFER
	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_WRITEBUFFER
	if (jffs2_cleanmarker_oob(c)) {
		int ret;

		if (c->mtd->block_isbad(c->mtd, jeb->offset))
			return BLK_STATE_BADBLOCK;

		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;
		default: 	return ret;
		}
	}
#endif

	if (jffs2_sum_active()) {
		struct jffs2_sum_marker *sm;
		void *sumptr = NULL;
		uint32_t sumlen;
	      
		if (!buf_size) {
			/* XIP case. Just look, point at the summary if it's there */
			sm = (void *)buf + c->sector_size - sizeof(*sm);
			if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
				sumptr = buf + je32_to_cpu(sm->offset);
				sumlen = c->sector_size - je32_to_cpu(sm->offset);
			}
		} else {
			/* If NAND flash, read a whole page of it. Else just the end */
			if (c->wbuf_pagesize)
				buf_len = c->wbuf_pagesize;
			else
				buf_len = sizeof(*sm);

			/* Read as much as we want into the _end_ of the preallocated buffer */
			err = jffs2_fill_scan_buf(c, buf + buf_size - buf_len, 
						  jeb->offset + c->sector_size - buf_len,
						  buf_len);				
			if (err)
				return err;

			sm = (void *)buf + buf_size - sizeof(*sm);
			if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
				sumlen = c->sector_size - je32_to_cpu(sm->offset);
				sumptr = buf + buf_size - sumlen;

				/* Now, make sure the summary itself is available */
				if (sumlen > buf_size) {
					/* Need to kmalloc for this. */
					sumptr = kmalloc(sumlen, GFP_KERNEL);
					if (!sumptr)
						return -ENOMEM;
					memcpy(sumptr + sumlen - buf_len, buf + buf_size - buf_len, buf_len);
				}
				if (buf_len < sumlen) {
					/* Need to read more so that the entire summary node is present */
					err = jffs2_fill_scan_buf(c, sumptr, 
								  jeb->offset + c->sector_size - sumlen,
								  sumlen - buf_len);				
					if (err)
						return err;
				}
			}

		}

		if (sumptr) {
			err = jffs2_sum_scan_sumnode(c, jeb, sumptr, sumlen, &pseudo_random);

			if (buf_size && sumlen > buf_size)
				kfree(sumptr);
			/* If it returns with a real error, bail. 
			   If it returns positive, that's a block classification
			   (i.e. BLK_STATE_xxx) so return that too.
			   If it returns zero, fall through to full scan. */
			if (err)
				return err;
		}
	}

	buf_ofs = jeb->offset;

	if (!buf_size) {
		/* This is the XIP case -- we're reading _directly_ from the flash chip */
		buf_len = c->sector_size;
	} else {
		buf_len = EMPTY_SCAN_SIZE(c->sector_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(c->sector_size) && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
		ofs += 4;

	if (ofs == EMPTY_SCAN_SIZE(c->sector_size)) {
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
		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));
		if (c->cleanmarker_size == 0)
			return BLK_STATE_CLEANMARKER;	/* don't bother with re-erase */
		else
			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));
		if ((err = jffs2_prealloc_raw_node_refs(c, jeb, 1)))
			return err;
		if ((err = jffs2_scan_dirty_space(c, jeb, ofs)))
			return err;
	}

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

	noise = 10;

	dbg_summary("no summary found in jeb 0x%08x. Apply original scan.\n",jeb->offset);

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

		jffs2_dbg_acct_paranoia_check_nolock(c, jeb);

		/* Make sure there are node refs available for use */
		err = jffs2_prealloc_raw_node_refs(c, jeb, 2);
		if (err)
			return err;

		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);
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			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)));
			if ((err = jffs2_scan_dirty_space(c, jeb, (jeb->offset + c->sector_size)-ofs)))
				return err;
			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, scan_end;

			empty_start = ofs;
			ofs += 4;
			scan_end = min_t(uint32_t, EMPTY_SCAN_SIZE(c->sector_size)/8, buf_len);

			D1(printk(KERN_DEBUG "Found empty flash at 0x%08x\n", ofs));
		more_empty:
			inbuf_ofs = ofs - buf_ofs;
			while (inbuf_ofs < scan_end) {
				if (unlikely(*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff)) {
					printk(KERN_WARNING "Empty flash at 0x%08x ends at 0x%08x\n",
					       empty_start, ofs);
					if ((err = jffs2_scan_dirty_space(c, jeb, ofs-empty_start)))
						return err;
					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 && !ref_next(jeb->first_node)) {
				D1(printk(KERN_DEBUG "%d bytes at start of block seems clean... assuming all clean\n", EMPTY_SCAN_SIZE(c->sector_size)));
				return BLK_STATE_CLEANMARKER;
			}
			if (!buf_size && (scan_end != buf_len)) {/* XIP/point case */
				scan_end = buf_len;
				goto more_empty;
			}
			
			/* 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;
			}
			/* point never reaches here */
			scan_end = buf_len;
			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);
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) == JFFS2_DIRTY_BITMASK) {
			D1(printk(KERN_DEBUG "Dirty bitmask at 0x%08x\n", ofs));
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) == JFFS2_OLD_MAGIC_BITMASK) {
			printk(KERN_WARNING "Old JFFS2 bitmask found at 0x%08x\n", ofs);
			printk(KERN_WARNING "You cannot use older JFFS2 filesystems with newer kernels\n");
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) != JFFS2_MAGIC_BITMASK) {
			/* OK. We're out of possibilities. Whinge and move on */
			noisy_printk(&noise, "jffs2_scan_eraseblock(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n",
				     JFFS2_MAGIC_BITMASK, ofs,
				     je16_to_cpu(node->magic));
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}
		/* We seem to have a node of sorts. Check the CRC */
		crcnode.magic = node->magic;
		crcnode.nodetype = cpu_to_je16( je16_to_cpu(node->nodetype) | JFFS2_NODE_ACCURATE);
		crcnode.totlen = node->totlen;
		hdr_crc = crc32(0, &crcnode, sizeof(crcnode)-4);

		if (hdr_crc != je32_to_cpu(node->hdr_crc)) {
			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",
				     ofs, je16_to_cpu(node->magic),
				     je16_to_cpu(node->nodetype),
				     je32_to_cpu(node->totlen),
				     je32_to_cpu(node->hdr_crc),
				     hdr_crc);
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}

		if (ofs + je32_to_cpu(node->totlen) > jeb->offset + c->sector_size) {
			/* Eep. Node goes over the end of the erase block. */
			printk(KERN_WARNING "Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
			       ofs, je32_to_cpu(node->totlen));
			printk(KERN_WARNING "Perhaps the file system was created with the wrong erase size?\n");
			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
				return err;
			ofs += 4;
			continue;
		}

		if (!(je16_to_cpu(node->nodetype) & JFFS2_NODE_ACCURATE)) {
			/* Wheee. This is an obsoleted node */
			D2(printk(KERN_DEBUG "Node at 0x%08x is obsolete. Skipping\n", ofs));
			if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(node->totlen)))))
				return err;
			ofs += PAD(je32_to_cpu(node->totlen));