inode-v23.c

mtd最新cvs jffs文件系统分析

/* Write, append or rewrite data to an existing file.  */
static ssize_t
jffs_file_write(struct file *filp, const char *buf, size_t count,
		loff_t *ppos)
{
	struct jffs_raw_inode raw_inode;
	struct jffs_control *c;
	struct jffs_file *f;
	struct jffs_node *node;
	struct dentry *dentry = filp->f_dentry;
	struct inode *inode = dentry->d_inode;
	int recoverable = 0;
	size_t written = 0;
	__u32 thiscount = count;
	loff_t pos = *ppos;
	int err;

	inode = filp->f_dentry->d_inode;

	D2(printk("***jffs_file_write(): inode: 0x%p (ino: %lu), "
		  "filp: 0x%p, buf: 0x%p, count: %d\n",
		  inode, inode->i_ino, filp, buf, count));

#if 0
	if (inode->i_sb->s_flags & MS_RDONLY) {
		D(printk("jffs_file_write(): MS_RDONLY\n"));
		err = -EROFS;
		goto out_isem;
	}
#endif	
	err = -EINVAL;

	if (!S_ISREG(inode->i_mode)) {
		D(printk("jffs_file_write(): inode->i_mode == 0x%08x\n",
				inode->i_mode));
		goto out_isem;
	}

	if (!(f = (struct jffs_file *)inode->u.generic_ip)) {
		D(printk("jffs_file_write(): inode->u.generic_ip = 0x%p\n",
				inode->u.generic_ip));
		goto out_isem;
	}

	c = f->c;

	/*
	 * This will never trigger with sane page sizes.  leave it in
	 * anyway, since I'm thinking about how to merge larger writes
	 * (the current idea is to poke a thread that does the actual
	 * I/O and starts by doing a down(&inode->i_sem).  then we
	 * would need to get the page cache pages and have a list of
	 * I/O requests and do write-merging here.
	 * -- prumpf
	 */
	thiscount = min(c->fmc->max_chunk_size - sizeof(struct jffs_raw_inode), count);

	D3(printk (KERN_NOTICE "file_write(): down biglock\n"));
	down(&c->fmc->biglock);

	/* Urgh. POSIX says we can do short writes if we feel like it. 
	 * In practice, we can't. Nothing will cope. So we loop until
	 * we're done.
	 *
	 * <_Anarchy_> posix and reality are not interconnected on this issue
	 */
	while (count) {
		/* Things are going to be written so we could allocate and
		   initialize the necessary data structures now.  */
		if (!(node = jffs_alloc_node())) {
			D(printk("jffs_file_write(): node == 0\n"));
			err = -ENOMEM;
			goto out;
		}

		node->data_offset = pos;
		node->removed_size = 0;

		/* Initialize the raw inode.  */
		raw_inode.magic = JFFS_MAGIC_BITMASK;
		raw_inode.ino = f->ino;
		raw_inode.pino = f->pino;

		raw_inode.mode = f->mode;

		raw_inode.uid = f->uid;
		raw_inode.gid = f->gid;
		raw_inode.atime = CURRENT_TIME;
		raw_inode.mtime = raw_inode.atime;
		raw_inode.ctime = f->ctime;
		raw_inode.offset = pos;
		raw_inode.dsize = thiscount;
		raw_inode.rsize = 0;
		raw_inode.nsize = f->nsize;
		raw_inode.nlink = f->nlink;
		raw_inode.spare = 0;
		raw_inode.rename = 0;
		raw_inode.deleted = 0;

		if (pos < f->size) {
			node->removed_size = raw_inode.rsize = min(thiscount, (__u32)(f->size - pos));

			/* If this node is going entirely over the top of old data,
			   we can allow it to go into the reserved space, because
			   we know that GC can reclaim the space later.
			*/
			if (pos + thiscount < f->size) {
				/* If all the data we're overwriting are _real_,
				   not just holes, then:
				   recoverable = 1;
				*/
			}
		}

		/* Write the new node to the flash.  */
		/* NOTE: We would be quite happy if jffs_write_node() wrote a
		   smaller node than we were expecting. There's no need for it
		   to waste the space at the end of the flash just because it's
		   a little smaller than what we asked for. But that's a whole
		   new can of worms which I'm not going to open this week. 
		   -- dwmw2.
		*/
		if ((err = jffs_write_node(c, node, &raw_inode, f->name,
					   (const unsigned char *)buf,
					   recoverable, f)) < 0) {
			D(printk("jffs_file_write(): jffs_write_node() failed.\n"));
			jffs_free_node(node);
			goto out;
		}

		written += err;
		buf += err;
		count -= err;
		pos += err;

		/* Insert the new node into the file system.  */
		if ((err = jffs_insert_node(c, f, &raw_inode, 0, node)) < 0) {
			goto out;
		}

		D3(printk("jffs_file_write(): new f_pos %ld.\n", (long)pos));

		thiscount = min(c->fmc->max_chunk_size - sizeof(struct jffs_raw_inode), count);
	}
 out:
	D3(printk (KERN_NOTICE "file_write(): up biglock\n"));
	up(&c->fmc->biglock);

	/* Fix things in the real inode.  */
	if (pos > inode->i_size) {
		inode->i_size = pos;
		inode->i_blocks = (inode->i_size + 511) >> 9;
	}
	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
	mark_inode_dirty(inode);
	invalidate_inode_pages(inode);

 out_isem:
	return err;
} /* jffs_file_write()  */

static ssize_t
jffs_prepare_write(struct file *filp, struct page *page,
                  unsigned from, unsigned to)
{
	/* FIXME: we should detect some error conditions here */

	/* Bugger that. We should make sure the page is uptodate */
	if (!Page_Uptodate(page) && (from || to < PAGE_CACHE_SIZE))
		return jffs_do_readpage_nolock(filp, page);

	return 0;
} /* jffs_prepare_write() */

static ssize_t
jffs_commit_write(struct file *filp, struct page *page,
                 unsigned from, unsigned to)
{
       void *addr = page_address(page) + from;
       /* XXX: PAGE_CACHE_SHIFT or PAGE_SHIFT */
       loff_t pos = (page->index<<PAGE_CACHE_SHIFT) + from;

       return jffs_file_write(filp, addr, to-from, &pos);
} /* jffs_commit_write() */

/* This is our ioctl() routine.  */
static int
jffs_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
	   unsigned long arg)
{
	struct jffs_control *c;
	int ret = 0;

	D2(printk("***jffs_ioctl(): cmd = 0x%08x, arg = 0x%08lx\n",
		  cmd, arg));

	if (!(c = (struct jffs_control *)inode->i_sb->u.generic_sbp)) {
		printk(KERN_ERR "JFFS: Bad inode in ioctl() call. "
		       "(cmd = 0x%08x)\n", cmd);
		return -EIO;
	}
	D3(printk (KERN_NOTICE "ioctl(): down biglock\n"));
	down(&c->fmc->biglock);

	switch (cmd) {
	case JFFS_PRINT_HASH:
		jffs_print_hash_table(c);
		break;
	case JFFS_PRINT_TREE:
		jffs_print_tree(c->root, 0);
		break;
	case JFFS_GET_STATUS:
		{
			struct jffs_flash_status fst;
			struct jffs_fmcontrol *fmc = c->fmc;
			printk("Flash status -- ");
			if (!access_ok(VERIFY_WRITE,
				       (struct jffs_flash_status *)arg,
				       sizeof(struct jffs_flash_status))) {
				D(printk("jffs_ioctl(): Bad arg in "
					 "JFFS_GET_STATUS ioctl!\n"));
				ret = -EFAULT;
				break;
			}
			fst.size = fmc->flash_size;
			fst.used = fmc->used_size;
			fst.dirty = fmc->dirty_size;
			fst.begin = fmc->head->offset;
			fst.end = fmc->tail->offset + fmc->tail->size;
			printk("size: %d, used: %d, dirty: %d, "
			       "begin: %d, end: %d\n",
			       fst.size, fst.used, fst.dirty,
			       fst.begin, fst.end);
			if (copy_to_user((struct jffs_flash_status *)arg,
					 &fst,
					 sizeof(struct jffs_flash_status))) {
				ret = -EFAULT;
			}
		}
		break;
	default:
		ret = -ENOTTY;
	}
	D3(printk (KERN_NOTICE "ioctl(): up biglock\n"));
	up(&c->fmc->biglock);
	return ret;
} /* jffs_ioctl()  */


static struct address_space_operations jffs_address_operations = {
	readpage: jffs_readpage,
	prepare_write: jffs_prepare_write,
	commit_write: jffs_commit_write,
};

static int jffs_fsync(struct file *f, struct dentry *d, int datasync)
{
	/* We currently have O_SYNC operations at all times.
	   Do nothing.
	*/
	return 0;
}


extern int generic_file_open(struct inode *, struct file *) __attribute__((weak));
extern loff_t generic_file_llseek(struct file *, loff_t, int) __attribute__((weak));

static struct file_operations jffs_file_operations =
{
	open:	generic_file_open,
	llseek:	generic_file_llseek,
	read:	generic_file_read,
	write:	generic_file_write,
	ioctl:	jffs_ioctl,
	mmap:	generic_file_mmap,
	fsync:	jffs_fsync,
};


static struct inode_operations jffs_file_inode_operations =
{
	lookup:  jffs_lookup,          /* lookup */
	setattr: jffs_setattr,
};


static struct file_operations jffs_dir_operations =
{
	readdir:	jffs_readdir,
};


static struct inode_operations jffs_dir_inode_operations =
{
	create:   jffs_create,
	lookup:   jffs_lookup,
	unlink:   jffs_unlink,
	symlink:  jffs_symlink,
	mkdir:    jffs_mkdir,
	rmdir:    jffs_rmdir,
	mknod:    jffs_mknod,
	rename:   jffs_rename,
	setattr:  jffs_setattr,
};


/* Initialize an inode for the VFS.  */
static void
jffs_read_inode(struct inode *inode)
{
	struct jffs_file *f;
	struct jffs_control *c;

	D3(printk("jffs_read_inode(): inode->i_ino == %lu\n", inode->i_ino));

	if (!inode->i_sb) {
		D(printk("jffs_read_inode(): !inode->i_sb ==> "
			 "No super block!\n"));
		return;
	}
	c = (struct jffs_control *)inode->i_sb->u.generic_sbp;
	D3(printk (KERN_NOTICE "read_inode(): down biglock\n"));
	down(&c->fmc->biglock);
	if (!(f = jffs_find_file(c, inode->i_ino))) {
		D(printk("jffs_read_inode(): No such inode (%lu).\n",
			 inode->i_ino));
		D3(printk (KERN_NOTICE "read_inode(): up biglock\n"));
		up(&c->fmc->biglock);
		return;
	}
	inode->u.generic_ip = (void *)f;
	inode->i_mode = f->mode;
	inode->i_nlink = f->nlink;
	inode->i_uid = f->uid;
	inode->i_gid = f->gid;
	inode->i_size = f->size;
	inode->i_atime = f->atime;
	inode->i_mtime = f->mtime;
	inode->i_ctime = f->ctime;
	inode->i_blksize = PAGE_SIZE;
	inode->i_blocks = (inode->i_size + 511) >> 9;
	if (S_ISREG(inode->i_mode)) {
		inode->i_op = &jffs_file_inode_operations;
		inode->i_fop = &jffs_file_operations;
		inode->i_mapping->a_ops = &jffs_address_operations;
	}
	else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &jffs_dir_inode_operations;
		inode->i_fop = &jffs_dir_operations;
	}
	else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &page_symlink_inode_operations;
		inode->i_mapping->a_ops = &jffs_address_operations;
	}
	else {
		/* If the node is a device of some sort, then the number of
		   the device should be read from the flash memory and then
		   added to the inode's i_rdev member.  */
		kdev_t rdev;
		jffs_read_data(f, (char *)&rdev, 0, sizeof(kdev_t));
		init_special_inode(inode, inode->i_mode, kdev_t_to_nr(rdev));
	}

	D3(printk (KERN_NOTICE "read_inode(): up biglock\n"));
	up(&c->fmc->biglock);
}


void
jffs_delete_inode(struct inode *inode)
{
	struct jffs_file *f;
	struct jffs_control *c;
	D3(printk("jffs_delete_inode(): inode->i_ino == %lu\n",
		  inode->i_ino));

	lock_kernel();
	inode->i_size = 0;
	inode->i_blocks = 0;
	inode->u.generic_ip = 0;
	clear_inode(inode);
	if (inode->i_nlink == 0) {
		c = (struct jffs_control *) inode->i_sb->u.generic_sbp;
		f = (struct jffs_file *) jffs_find_file (c, inode->i_ino);
		jffs_possibly_delete_file(f);
	}

	unlock_kernel();
}


void
jffs_write_super(struct super_block *sb)
{
	struct jffs_control *c = (struct jffs_control *)sb->u.generic_sbp;

	jffs_garbage_collect_trigger(c);
}

static struct super_operations jffs_ops =
{
	read_inode:   jffs_read_inode,
	delete_inode: jffs_delete_inode,
	put_super:    jffs_put_super,
	write_super:  jffs_write_super,
	statfs:       jffs_statfs,
};


static DECLARE_FSTYPE_DEV(jffs_fs_type, "jffs", jffs_read_super);

static int __init
init_jffs_fs(void)
{
	printk(KERN_INFO "JFFS version " JFFS_VERSION_STRING
		", (C) 1999, 2000  Axis Communications AB\n");
	
	fm_cache = kmem_cache_create("jffs_fm", sizeof(struct jffs_fm),
				     0, SLAB_HWCACHE_ALIGN, NULL, NULL);
	node_cache = kmem_cache_create("jffs_node",sizeof(struct jffs_node),
				       0, SLAB_HWCACHE_ALIGN, NULL, NULL);
	return register_filesystem(&jffs_fs_type);
}

static void __exit
exit_jffs_fs(void)
{
	unregister_filesystem(&jffs_fs_type);
	kmem_cache_destroy(fm_cache);
	kmem_cache_destroy(node_cache);
}

EXPORT_NO_SYMBOLS;

module_init(init_jffs_fs)
module_exit(exit_jffs_fs)

MODULE_DESCRIPTION("The Journalling Flash File System");
MODULE_AUTHOR("Axis Communications AB.");
MODULE_LICENSE("GPL");