intrep.c

mtd最新cvs jffs文件系统分析

/*
 * JFFS -- Journaling Flash File System, Linux implementation.
 *
 * Copyright (C) 1999, 2000  Axis Communications, Inc.
 *
 * Created by Finn Hakansson <[e-mail]>.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * $Id: intrep.c,v 1.105 2003/07/02 20:39:55 acurtis Exp $
 *
 * Ported to Linux 2.3.x and MTD:
 * Copyright (C) 2000  Alexander Larsson ([e-mail]), Cendio Systems AB
 *
 */

/* This file contains the code for the internal structure of the
   Journaling Flash File System, JFFS.  */

/*
 * Todo list:
 *
 * memcpy_to_flash() and memcpy_from_flash() functions.
 *
 * Implementation of hard links.
 *
 * Organize the source code in a better way. Against the VFS we could
 * have jffs_ext.c, and against the block device jffs_int.c.
 * A better file-internal organization too.
 *
 * A better checksum algorithm.
 *
 * Consider endianness stuff. ntohl() etc.
 *
 * Are we handling the atime, mtime, ctime members of the inode right?
 *
 * Remove some duplicated code. Take a look at jffs_write_node() and
 * jffs_rewrite_data() for instance.
 *
 * Implement more meaning of the nlink member in various data structures.
 * nlink could be used in conjunction with hard links for instance.
 *
 * Better memory management. Allocate data structures in larger chunks
 * if possible.
 *
 * If too much meta data is stored, a garbage collect should be issued.
 * We have experienced problems with too much meta data with for instance
 * log files.
 *
 * Improve the calls to jffs_ioctl(). We would like to retrieve more
 * information to be able to debug (or to supervise) JFFS during run-time.
 *
 */

#define __NO_VERSION__
#include <linux/config.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jffs.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/pagemap.h>
#include <linux/locks.h>
#include <asm/semaphore.h>
#include <asm/byteorder.h>
#include <linux/version.h>
#include <linux/smp_lock.h>
#include <linux/sched.h>
#include <linux/ctype.h>

#include <linux/mtd/compatmac.h>

#include "intrep.h"
#include "jffs_fm.h"

long no_jffs_node = 0;
long no_jffs_file = 0;
#if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
long no_jffs_control = 0;
long no_jffs_raw_inode = 0;
long no_jffs_node_ref = 0;
long no_jffs_fm = 0;
long no_jffs_fmcontrol = 0;
long no_hash = 0;
long no_name = 0;
#endif

static int jffs_scan_flash(struct jffs_control *c);
static int jffs_update_file(struct jffs_file *f, struct jffs_node *node);

#if CONFIG_JFFS_FS_VERBOSE > 0
static __u8
flash_read_u8(struct mtd_info *mtd, loff_t from)
{
	size_t retlen;
	__u8 ret;
	int res;

	res = MTD_READ(mtd, from, 1, &retlen, &ret);
	if (retlen != 1) {
		printk("Didn't read a byte in flash_read_u8(). Returned %d\n", res);
		return 0;
	}

	return ret;
}

static void
jffs_hexdump(struct mtd_info *mtd, loff_t pos, int size)
{
	char line[16];
	int j = 0;

	while (size > 0) {
		int i;

		printk("%ld:", (long) pos);
		for (j = 0; j < 16; j++) {
			line[j] = flash_read_u8(mtd, pos++);
		}
		for (i = 0; i < j; i++) {
			if (!(i & 1)) {
				printk(" %.2x", line[i] & 0xff);
			}
			else {
				printk("%.2x", line[i] & 0xff);
			}
		}

		/* Print empty space */
		for (; i < 16; i++) {
			if (!(i & 1)) {
				printk("   ");
			}
			else {
				printk("  ");
			}
		}
		printk("  ");

		for (i = 0; i < j; i++) {
			if (isgraph(line[i])) {
				printk("%c", line[i]);
			}
			else {
				printk(".");
			}
		}
		printk("\n");
		size -= 16;
	}
}

#endif

#define flash_safe_acquire(arg)
#define flash_safe_release(arg)


static int
flash_safe_read(struct mtd_info *mtd, loff_t from,
		u_char *buf, size_t count)
{
	size_t retlen;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_read(%p, %08x, %p, %08x)\n",
		  mtd, (unsigned int) from, buf, count));

	res = MTD_READ(mtd, from, count, &retlen, buf);
	if (retlen != count) {
		panic("Didn't read all bytes in flash_safe_read(). Returned %d\n", res);
	}
	return res?res:retlen;
}


static __u32
flash_read_u32(struct mtd_info *mtd, loff_t from)
{
	size_t retlen;
	__u32 ret;
	int res;

	res = MTD_READ(mtd, from, 4, &retlen, (unsigned char *)&ret);
	if (retlen != 4) {
		printk("Didn't read all bytes in flash_read_u32(). Returned %d\n", res);
		return 0;
	}

	return ret;
}


static int
flash_safe_write(struct mtd_info *mtd, loff_t to,
		 const u_char *buf, size_t count)
{
	size_t retlen;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_write(%p, %08x, %p, %08x)\n",
		  mtd, (unsigned int) to, buf, count));

	res = MTD_WRITE(mtd, to, count, &retlen, buf);
	if (retlen != count) {
		printk("Didn't write all bytes in flash_safe_write(). Returned %d\n", res);
	}
	return res?res:retlen;
}


static int
flash_safe_writev(struct mtd_info *mtd, const struct iovec *vecs,
			unsigned long iovec_cnt, loff_t to)
{
	size_t retlen, retlen_a;
	int i;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_writev(%p, %08x, %p)\n",
		  mtd, (unsigned int) to, vecs));
	
	if (mtd->writev) {
		res = MTD_WRITEV(mtd, vecs, iovec_cnt, to, &retlen);
		return res ? res : retlen;
	}
	/* Not implemented writev. Repeatedly use write - on the not so
	   unreasonable assumption that the mtd driver doesn't care how
	   many write cycles we use. */
	res=0;
	retlen=0;

	for (i=0; !res && i<iovec_cnt; i++) {
		res = MTD_WRITE(mtd, to, vecs[i].iov_len, &retlen_a, vecs[i].iov_base);
		if (retlen_a != vecs[i].iov_len) {
			printk("Didn't write all bytes in flash_safe_writev(). Returned %d\n", res);
			if (i != iovec_cnt-1)
				return -EIO;
		}
		/* If res is non-zero, retlen_a is undefined, but we don't
		   care because in that case it's not going to be 
		   returned anyway.
		*/
		to += retlen_a;
		retlen += retlen_a;
	}
	return res?res:retlen;
}


static int
flash_memset(struct mtd_info *mtd, loff_t to,
	     const u_char c, size_t size)
{
	static unsigned char pattern[64];
	int i;

	/* fill up pattern */

	for(i = 0; i < 64; i++)
		pattern[i] = c;

	/* write as many 64-byte chunks as we can */

	while (size >= 64) {
		flash_safe_write(mtd, to, pattern, 64);
		size -= 64;
		to += 64;
	}

	/* and the rest */

	if(size)
		flash_safe_write(mtd, to, pattern, size);

	return size;
}


static void
intrep_erase_callback(struct erase_info *done)
{
	wait_queue_head_t *wait_q;

	wait_q = (wait_queue_head_t *)done->priv;

	wake_up(wait_q);
}


static int
flash_erase_region(struct mtd_info *mtd, loff_t start,
		   size_t size)
{
	struct erase_info *erase;
	DECLARE_WAITQUEUE(wait, current);
	wait_queue_head_t wait_q;

	erase = kmalloc(sizeof(struct erase_info), GFP_KERNEL);
	if (!erase)
		return -ENOMEM;

	init_waitqueue_head(&wait_q);

	erase->mtd = mtd;
	erase->callback = intrep_erase_callback;
	erase->addr = start;
	erase->len = size;
	erase->priv = (u_long)&wait_q;

	/* FIXME: Use TASK_INTERRUPTIBLE and deal with being interrupted */
	set_current_state(TASK_UNINTERRUPTIBLE);
	add_wait_queue(&wait_q, &wait);

	if (MTD_ERASE(mtd, erase) < 0) {
		set_current_state(TASK_RUNNING);
		remove_wait_queue(&wait_q, &wait);
		kfree(erase);

		printk(KERN_WARNING "flash: erase of region [0x%lx, 0x%lx] "
		       "totally failed\n", (long)start, (long)start + size);

		return -1;
	}

	schedule(); /* Wait for flash to finish. */
	remove_wait_queue(&wait_q, &wait);

	kfree(erase);

	return 0;
}

/* This routine calculates checksums in JFFS.  */
__u32
jffs_checksum(const void *data, int size)
{
	__u32 sum = 0;
	__u8 *ptr = (__u8 *)data;
	while (size-- > 0) {
		sum += *ptr++;
	}
	D3(printk(", result: 0x%08x\n", sum));
	return sum;
}


int
jffs_checksum_flash(struct mtd_info *mtd, loff_t start, int size, __u32 *result)
{
	__u32 sum = 0;
	loff_t ptr = start;
	__u8 *read_buf;
	int i, length;

	/* Allocate read buffer */
	read_buf = (__u8 *) kmalloc (sizeof(__u8) * 4096, GFP_KERNEL);
	if (!read_buf) {
		printk(KERN_NOTICE "kmalloc failed in jffs_checksum_flash()\n");
		return -ENOMEM;
	}
	/* Loop until checksum done */
	while (size) {
		/* Get amount of data to read */
		if (size < 4096)
			length = size;
		else
			length = 4096;

		/* Perform flash read */
		D3(printk(KERN_NOTICE "jffs_checksum_flash\n"));
		flash_safe_read(mtd, ptr, &read_buf[0], length);

		/* Compute checksum */
		for (i=0; i < length ; i++)
			sum += read_buf[i];

		/* Update pointer and size */
		size -= length;
		ptr += length;
	}

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

	/* Return result */
	D3(printk("checksum result: 0x%08x\n", sum));
	*result = sum;
	return 0;
}

static __inline__ void jffs_fm_write_lock(struct jffs_fmcontrol *fmc)
{
  //	down(&fmc->wlock);
}

static __inline__ void jffs_fm_write_unlock(struct jffs_fmcontrol *fmc)
{
  //	up(&fmc->wlock);
}


/* Create and initialize a new struct jffs_file.  */
static struct jffs_file *
jffs_create_file(struct jffs_control *c,
		 const struct jffs_raw_inode *raw_inode)
{
	struct jffs_file *f;

	if (!(f = (struct jffs_file *)kmalloc(sizeof(struct jffs_file),
					      GFP_KERNEL))) {
		D(printk("jffs_create_file(): Failed!\n"));
		return 0;
	}
	no_jffs_file++;
	memset(f, 0, sizeof(struct jffs_file));
	f->ino = raw_inode->ino;
	f->pino = raw_inode->pino;
	f->nlink = raw_inode->nlink;
	f->deleted = raw_inode->deleted;
	f->c = c;

	return f;
}


/* Build a control block for the file system.  */
static struct jffs_control *
jffs_create_control(kdev_t dev)
{
	struct jffs_control *c;
	register int s = sizeof(struct jffs_control);
	int i;
	D(char *t = 0);

	D2(printk("jffs_create_control()\n"));

	if (!(c = (struct jffs_control *)kmalloc(s, GFP_KERNEL))) {
		goto fail_control;
	}
	DJM(no_jffs_control++);
	c->root = 0;
	c->gc_task = 0;
	c->hash_len = JFFS_HASH_SIZE;
	s = sizeof(struct list_head) * c->hash_len;
	if (!(c->hash = (struct list_head *)kmalloc(s, GFP_KERNEL))) {
		goto fail_hash;
	}
	DJM(no_hash++);
	for (i = 0; i < c->hash_len; i++)
		INIT_LIST_HEAD(&c->hash[i]);
	if (!(c->fmc = jffs_build_begin(c, dev))) {
		goto fail_fminit;
	}
	c->next_ino = JFFS_MIN_INO + 1;
	c->delete_list = (struct jffs_delete_list *) 0;
	return c;

fail_fminit:
	D(t = "c->fmc");
fail_hash:
	kfree(c);
	DJM(no_jffs_control--);
	D(t = t ? t : "c->hash");
fail_control:
	D(t = t ? t : "control");
	D(printk("jffs_create_control(): Allocation failed: (%s)\n", t));
	return (struct jffs_control *)0;
}


/* Clean up all data structures associated with the file system.  */
void
jffs_cleanup_control(struct jffs_control *c)
{
	D2(printk("jffs_cleanup_control()\n"));

	if (!c) {
		D(printk("jffs_cleanup_control(): c == NULL !!!\n"));
		return;
	}

	while (c->delete_list) {