intrep.c

mtd最新cvs jffs文件系统分析

					    */ 
				           num_free_space++;
				           D1(printk("Free space accepted: Starting 0x%x for 0x%x bytes\n",
						     (unsigned int) start, (unsigned int) (pos - start)));

					   if (largest_hole < pos - start) {
						   
						   D3(printk("was hole = %x end_offset = %x\n",
						          largest_hole, hole_end_offset));
						   if (fmc->head){
							   largest_hole    = pos - start;
							   hole_end_offset = pos;
							}

						   D3(printk("now = %x end_offset = %x\n",
						          largest_hole, hole_end_offset));
						}
				 }else{
				         num_free_spc_not_accp++;
					 D1(printk("Free space (#%i) found but *Not* accepted: Starting "
						   "0x%x for 0x%x bytes\n", num_free_spc_not_accp, 
						   (unsigned int) start, 
						   (unsigned int) (pos - start)));
					 
					 /* Mark this space as dirty. We already have our free space. */
					 D1(printk("Dirty space: Starting 0x%x for 0x%x bytes\n",
						   (unsigned int) start, (unsigned int) (pos - start)));
					 jffs_fmalloced(fmc, (__u32) start,
							(__u32) (pos - start), 0);				           
				}
				 
			}
			if(num_free_space > NUMFREEALLOWED){
			         printk(KERN_WARNING "jffs_scan_flash(): Found free space "
					"number %i. Only %i free space is allowed.\n",
					num_free_space, NUMFREEALLOWED);			      
			}
			continue;

		case JFFS_DIRTY_BITMASK:
			/* We have found 0x00000000 at this position.  Scan as far
			   as possible to find out how much is dirty.  */
			D1(printk("jffs_scan_flash(): 0x00000000 at pos 0x%lx.\n",
				  (long)pos));
			for (; pos < end
			       && JFFS_DIRTY_BITMASK == flash_read_u32(fmc->mtd, pos);
			     pos += 4);
			D1(printk("jffs_scan_flash(): 0x00 ended at "
				  "pos 0x%lx.\n", (long)pos));
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), 0);
			continue;

		case JFFS_MAGIC_BITMASK:
			/* We have probably found a new raw inode.  */
			break;

		default:
		bad_inode:
			/* We're f*cked.  This is not solved yet.  We have
			   to scan for the magic pattern.  */
			D1(printk("*************** Dirty flash memory or "
				  "bad inode: "
				  "hexdump(pos = 0x%lx, len = %d):\n",
				  (long)pos,
				  end - pos > 128 ? 128 : end - pos));
			D1(jffs_hexdump(fmc->mtd, pos,
			                end - pos > 128 ? 128 : end - pos));

			for (pos += 4; pos < end; pos += 4) {
				switch (flash_read_u32(fmc->mtd, pos)) {
				case JFFS_MAGIC_BITMASK:
				case JFFS_EMPTY_BITMASK:
					/* handle these in the main switch() loop */
					goto cont_scan;

				default:
					break;
				}
			}

			cont_scan:
			/* First, mark as dirty the region
			   which really does contain crap. */
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start),
				       0);
			
			continue;
		}/* switch */

		/* We have found the beginning of an inode.  Create a
		   node for it unless there already is one available.  */
		if (!node) {
			if (!(node = jffs_alloc_node())) {
				/* Free read buffer */
				kfree (read_buf);

				/* Release the flash device */
				flash_safe_release(fmc->mtd);
	
				return -ENOMEM;
			}
			DJM(no_jffs_node++);
		}

		/* Read the next raw inode.  */

		flash_safe_read(fmc->mtd, pos, (u_char *) &raw_inode,
				sizeof(struct jffs_raw_inode));

		/* When we compute the checksum for the inode, we never
		   count the 'accurate' or the 'checksum' fields.  */
		tmp_accurate = raw_inode.accurate;
		tmp_chksum = raw_inode.chksum;
		raw_inode.accurate = 0;
		raw_inode.chksum = 0;
		checksum = jffs_checksum(&raw_inode,
					 sizeof(struct jffs_raw_inode));
		raw_inode.accurate = tmp_accurate;
		raw_inode.chksum = tmp_chksum;

		D3(printk("*** We have found this raw inode at pos 0x%lx "
			  "on the flash:\n", (long)pos));
		D3(jffs_print_raw_inode(&raw_inode));

		if (checksum != raw_inode.chksum) {
			D1(printk("jffs_scan_flash(): Bad checksum: "
				  "checksum = %u, "
				  "raw_inode.chksum = %u\n",
				  checksum, raw_inode.chksum));
			pos += sizeof(struct jffs_raw_inode);
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), 0);
			/* Reuse this unused struct jffs_node.  */
			continue;
		}

		/* Check the raw inode read so far.  Start with the
		   maximum length of the filename.  */
		if (raw_inode.nsize > JFFS_MAX_NAME_LEN) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "JFFS node with name too large\n");
			goto bad_inode;
		}

		if (raw_inode.rename && raw_inode.dsize != sizeof(__u32)) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "rename node with dsize %u.\n",
			       raw_inode.dsize);
			jffs_print_raw_inode(&raw_inode);
			goto bad_inode;
		}

		/* The node's data segment should not exceed a
		   certain length.  */
		if (raw_inode.dsize > fmc->max_chunk_size) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "JFFS node with dsize (0x%x) > max_chunk_size (0x%x)\n",
			       raw_inode.dsize, fmc->max_chunk_size);
			goto bad_inode;
		}

		pos += sizeof(struct jffs_raw_inode);

		/* This shouldn't be necessary because a node that
		   violates the flash boundaries shouldn't be written
		   in the first place. */
		if (pos >= end) {
			goto check_node;
		}

		/* Read the name.  */
		*name = 0;
		if (raw_inode.nsize) {
		        flash_safe_read(fmc->mtd, pos, name, raw_inode.nsize);
			name[raw_inode.nsize] = '\0';
			pos += raw_inode.nsize
			       + JFFS_GET_PAD_BYTES(raw_inode.nsize);
			D3(printk("name == \"%s\"\n", name));
			checksum = jffs_checksum(name, raw_inode.nsize);
			if (checksum != raw_inode.nchksum) {
				D1(printk("jffs_scan_flash(): Bad checksum: "
					  "checksum = %u, "
					  "raw_inode.nchksum = %u\n",
					  checksum, raw_inode.nchksum));
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), 0);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}
			if (pos >= end) {
				goto check_node;
			}
		}

		/* Read the data, if it exists, in order to be sure it
		   matches the checksum.  */
		if (raw_inode.dsize) {
			if (raw_inode.rename) {
				deleted_file = flash_read_u32(fmc->mtd, pos);
			}
			if (jffs_checksum_flash(fmc->mtd, pos, raw_inode.dsize, &checksum)) {
				printk("jffs_checksum_flash() failed to calculate a checksum\n");
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), 0);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}				
			pos += raw_inode.dsize
			       + JFFS_GET_PAD_BYTES(raw_inode.dsize);

			if (checksum != raw_inode.dchksum) {
				D1(printk("jffs_scan_flash(): Bad checksum: "
					  "checksum = %u, "
					  "raw_inode.dchksum = %u\n",
					  checksum, raw_inode.dchksum));
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), 0);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}
		}

		check_node:

		/* Remember the highest inode number in the whole file
		   system.  This information will be used when assigning
		   new files new inode numbers.  */
		if (c->next_ino <= raw_inode.ino) {
			c->next_ino = raw_inode.ino + 1;
		}

		if (raw_inode.accurate) {
			int err;
			node->data_offset = raw_inode.offset;
			node->data_size = raw_inode.dsize;
			node->removed_size = raw_inode.rsize;
			/* Compute the offset to the actual data in the
			   on-flash node.  */
			node->fm_offset
			= sizeof(struct jffs_raw_inode)
			  + raw_inode.nsize
			  + JFFS_GET_PAD_BYTES(raw_inode.nsize);
			node->fm = jffs_fmalloced(fmc, (__u32) start,
						  (__u32) (pos - start),
						  node);
			if (!node->fm) {
				D(printk("jffs_scan_flash(): !node->fm\n"));
				jffs_free_node(node);
				DJM(no_jffs_node--);

				/* Free read buffer */
				kfree (read_buf);

				/* Release the flash device */
				flash_safe_release(fmc->mtd);

				return -ENOMEM;
			}
			if (raw_inode.rename) {
				struct jffs_delete_list *dl
				= (struct jffs_delete_list *)
				  kmalloc(sizeof(struct jffs_delete_list),
					  GFP_KERNEL);
				if (!dl) {
					D(printk("jffs_scan_flash: !dl\n"));
					jffs_free_node(node);
					DJM(no_jffs_node--);

					/* Release the flash device */
					flash_safe_release(fmc->flash_part);

					/* Free read buffer */
					kfree (read_buf);

					return -ENOMEM;
				}
				dl->ino = deleted_file;
				dl->next = c->delete_list;
				c->delete_list = dl;
				node->data_size = 0;
			}
			if ((err = jffs_insert_node(c, 0, &raw_inode,
						    name, node)) < 0) {
				printk("JFFS: Failed to handle raw inode. "
				       "(err = %d)\n", err);
				break;
			}
			D3(jffs_print_node(node));
			node = 0; /* Don't free the node!  */
		}
		else {
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), 0);
			D3(printk("jffs_scan_flash(): Just found an obsolete "
				  "raw_inode. Continuing the scan...\n"));
			/* Reuse this unused struct jffs_node.  */
		}
	}

	if (node) {
		jffs_free_node(node);
		DJM(no_jffs_node--);
	}
	if (fmc->head && fmc->tail_extra &&
	    fmc->head->offset + fmc->flash_size -
			fmc->tail_extra->offset - fmc->tail_extra->size > largest_hole) {
		head_offset = fmc->head->offset;
	}
	else {
		head_offset = hole_end_offset;
	}
	
	if (jffs_build_end(fmc, head_offset) < 0) {
		D(printk("jffs_build_end() failed\n"));
		return -ENOMEM;
	}

	/* Free read buffer */
	kfree (read_buf);

	if(!num_free_space){
	        printk(KERN_WARNING "jffs_scan_flash(): Did not find even a single "
		       "chunk of free space. This is BAD!\n");
	}

	/* Return happy */
	D3(printk("jffs_scan_flash(): Leaving...\n"));
	flash_safe_release(fmc->mtd);

	/* This is to trap the "free size accounting screwed error. */
	free_chunk_size1 = jffs_free_size1(fmc);
	free_chunk_size2 = jffs_free_size2(fmc);

	if (free_chunk_size1 + free_chunk_size2 != fmc->free_size) {

		printk(KERN_WARNING "jffs_scan_falsh():Free size accounting screwed\n");
		printk(KERN_WARNING "jfffs_scan_flash():free_chunk_size1 == 0x%x, "
		       "free_chunk_size2 == 0x%x, fmc->free_size == 0x%x\n", 
		       free_chunk_size1, free_chunk_size2, fmc->free_size);

		return -1; /* Do NOT mount f/s so that we can inspect what happened.
			      Mounting this  screwed up f/s will screw us up anyway.
			    */
	}	

	return 0; /* as far as we are concerned, we are happy! */
} /* jffs_scan_flash()  */


/* Insert any kind of node into the file system.  Take care of data
   insertions and deletions.  Also remove redundant information. The
   memory allocated for the `name' is regarded as "given away" in the
   caller's perspective.  */
int
jffs_insert_node(struct jffs_control *c, struct jffs_file *f,
		 const struct jffs_raw_inode *raw_inode,
		 const char *name, struct jffs_node *node)
{
	int update_name = 0;
	int insert_into_tree = 0;

	D2(printk("jffs_insert_node(): ino = %u, version = %u, "
		  "name = \"%s\", deleted = %d\n",
		  raw_inode->ino, raw_inode->version,
		  ((name && *name) ? name : ""), raw_inode->deleted));

	/* If there doesn't exist an associated jffs_file, then
	   create, initialize and insert one into the file system.  */
	if (!f && !(f = jffs_find_file(c, raw_inode->ino))) {
		if (!(f = jffs_create_file(c, raw_inode))) {
			return -ENOMEM;
		}
		jffs_insert_file_into_hash(f);
		insert_into_tree = 1;
	}
	node->ino = raw_inode->ino;
	node->version = raw_inode->version;
	node->data_size = raw_inode->dsize;
	node->fm_offset = sizeof(struct jffs_raw_inode) + raw_inode->nsize
			  + JFFS_GET_PAD_BYTES(raw_inode->nsize);
	node->name_size = raw_inode->nsize;

	/* Now insert the node at the correct position into the file's
	   version list.  */
	if (!f->version_head) {
		/* This is the first node.  */
		f->version_head = node;
		f->version_tail = node;
		node->version_prev = 0;
		node->version_next = 0;
		f->highest_version = node->version;
		update_name = 1;
		f->mode = raw_inode->mode;
		f->uid = raw_inode->uid;
		f->gid = raw_inode->gid;
		f->atime = raw_inode->atime;
		f->mtime = raw_inode->mtime;
		f->ctime = raw_inode->ctime;
	}
	else if ((f->highest_version < node->version)
		 || (node->version == 0)) {
		/* Insert at the end of the list.  I.e. this node is the
		   newest one so far.  */
		node->version_prev = f->version_tail;
		node->version_next = 0;
		f->version_tail->version_next = node;
		f->version_tail = node;
		f->highest_version = node->version;
		update_name = 1;
		f->pino = raw_inode->pino;
		f->mode = raw_inode->mode;
		f->uid = raw_inode->uid;
		f->gid = raw_inode->gid;
		f->atime = raw_inode->atime;
		f->mtime = raw_inode->mtime;
		f->ctime = raw_inode->ctime;
	}
	else if (f->version_head->version > node->version) {
		/* Insert at the bottom of the list.  */
		node->version_prev = 0;
		node->version_next = f->version_head;
		f->version_head->version_prev = node;
		f->version_head = node;
		if (!f->name) {
			update_name = 1;
		}
	}
	else {
		struct jffs_node *n;
		int newer_name = 0;
		/* Search for the insertion position starting from
		   the tail (newest node).  */
		for (n = f->version_tail; n; n = n->version_prev) {
			if (n->version < node->version) {
				node->version_prev = n;
				node->version_next = n->version_next;
				node->version_next->version_prev = node;
				n->version_next = node;
				if (!newer_name) {
					update_name = 1;
				}
				break;
			}
			if (n->name_size) {
				newer_name = 1;
			}
		}
	}

	/* Deletion is irreversible. If any 'deleted' node is ever
	   written, the file is deleted */
	if (raw_inode->deleted)
		f->deleted = raw_inode->deleted;

	/* Perhaps update the name.  */
	if (raw_inode->nsize && update_name && name && *name && (name != f->name)) {
		if (f->name) {
			kfree(f->name);
			DJM(no_name--);
		}
		if (!(f->name = (char *) kmalloc(raw_inode->nsize + 1,
						 GFP_KERNEL))) {
			return -ENOMEM;
		}
		DJM(no_name++);
		memcpy(f->name, name, raw_inode->nsize);
		f->name[raw_inode->nsize] = '\0';
		f->nsize = raw_inode->nsize;
		D3(printk("jffs_insert_node(): Updated the name of "
			  "the file to \"%s\".\n", name));
	}

	if (!c->building_fs) {
		D3(printk("jffs_insert_node(): ---------------------------"
			  "------------------------------------------- 1\n"));
		if (insert_into_tree) {
			jffs_insert_file_into_tree(f);
		}
		/* Once upon a time, we would call jffs_possibly_delete_file()
		   here. That causes an oops if someone's still got the file
		   open, so now we only do it in jffs_delete_inode()
		   -- dwmw2
		*/
		if (node->data_size || node->removed_size) {
			jffs_update_file(f, node);