file.c

elinux jffs初始版本 具体了解JFFS的文件系统！

/*
 *  file.c
 *
 *  Copyright (C) 1995, 1996 by Paal-Kr. Engstad and Volker Lendecke
 *
 */

#include <asm/segment.h>
#include <asm/system.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/smb_fs.h>
#include <linux/malloc.h>

static inline int
min(int a, int b)
{
	return a < b ? a : b;
}

static int
smb_fsync(struct inode *inode, struct file *file)
{
	return 0;
}

int
smb_make_open(struct inode *i, int right)
{
	struct smb_dirent *dirent;

	if (i == NULL)
	{
		printk("smb_make_open: got NULL inode\n");
		return -EINVAL;
	}
	dirent = &(SMB_INOP(i)->finfo);

	DDPRINTK("smb_make_open: dirent->opened = %d\n", dirent->opened);

	if ((dirent->opened) == 0)
	{
		/* tries max. rights */
		int open_result = smb_proc_open(SMB_SERVER(i),
						SMB_INOP(i)->dir,
						dirent->name, dirent->len,
						dirent);
		if (open_result)
		{
			return open_result;
		}
	}
	if (((right == O_RDONLY) && ((dirent->access == O_RDONLY)
				     || (dirent->access == O_RDWR)))
	    || ((right == O_WRONLY) && ((dirent->access == O_WRONLY)
					|| (dirent->access == O_RDWR)))
	    || ((right == O_RDWR) && (dirent->access == O_RDWR)))
		return 0;

	return -EACCES;
}

static int
smb_file_read(struct inode *inode, struct file *file, char *buf, int count)
{
	int result, bufsize, to_read, already_read;
	off_t pos;
	int errno;

	DPRINTK("smb_file_read: enter %s\n", SMB_FINFO(inode)->name);

	if (!inode)
	{
		DPRINTK("smb_file_read: inode = NULL\n");
		return -EINVAL;
	}
	if (!S_ISREG(inode->i_mode))
	{
		DPRINTK("smb_file_read: read from non-file, mode %07o\n",
			inode->i_mode);
		return -EINVAL;
	}
	if ((errno = smb_make_open(inode, O_RDONLY)) != 0)
		return errno;

	pos = file->f_pos;

	if (pos + count > inode->i_size)
	{
		count = inode->i_size - pos;
	}
	if (count <= 0)
	{
		return 0;
	}
	bufsize = SMB_SERVER(inode)->max_xmit - SMB_HEADER_LEN - 5 * 2 - 5;

	already_read = 0;

	/* First read in as much as possible for each bufsize. */
	while (already_read < count)
	{
		to_read = min(bufsize, count - already_read);
		result = smb_proc_read(SMB_SERVER(inode), SMB_FINFO(inode),
				       pos, to_read, buf, 1);
		if (result < 0)
		{
			return result;
		}
		pos += result;
		buf += result;
		already_read += result;

		if (result < to_read)
		{
			break;
		}
	}

	file->f_pos = pos;

	if (!IS_RDONLY(inode))
		inode->i_atime = CURRENT_TIME;
	inode->i_dirt = 1;

	DPRINTK("smb_file_read: exit %s\n", SMB_FINFO(inode)->name);

	return already_read;
}

static int
smb_file_write(struct inode *inode, struct file *file, const char *buf,
	       int count)
{
	int result, bufsize, to_write, already_written;
	off_t pos;
	int errno;

	if (!inode)
	{
		DPRINTK("smb_file_write: inode = NULL\n");
		return -EINVAL;
	}
	if (!S_ISREG(inode->i_mode))
	{
		DPRINTK("smb_file_write: write to non-file, mode %07o\n",
			inode->i_mode);
		return -EINVAL;
	}
	DPRINTK("smb_file_write: enter %s\n", SMB_FINFO(inode)->name);

	if (count <= 0)
	{
		return 0;
	}
	if ((errno = smb_make_open(inode, O_RDWR)) != 0)
	{
		return errno;
	}
	pos = file->f_pos;

	if (file->f_flags & O_APPEND)
		pos = inode->i_size;

	bufsize = SMB_SERVER(inode)->max_xmit - SMB_HEADER_LEN - 5 * 2 - 5;

	already_written = 0;

	DPRINTK("smb_write_file: blkmode = %d, blkmode & 2 = %d\n",
		SMB_SERVER(inode)->blkmode,
		SMB_SERVER(inode)->blkmode & 2);

	while (already_written < count)
	{
		to_write = min(bufsize, count - already_written);
		result = smb_proc_write(SMB_SERVER(inode), SMB_FINFO(inode),
					pos, to_write, buf);

		if (result < 0)
		{
			return result;
		}
		pos += result;
		buf += result;
		already_written += result;

		if (result < to_write)
		{
			break;
		}
	}

	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	inode->i_dirt = 1;

	file->f_pos = pos;

	if (pos > inode->i_size)
	{
		inode->i_size = pos;
	}
	DPRINTK("smb_file_write: exit %s\n", SMB_FINFO(inode)->name);

	return already_written;
}

static struct file_operations smb_file_operations =
{
	NULL,			/* lseek - default */
	smb_file_read,		/* read */
	smb_file_write,		/* write */
	NULL,			/* readdir - bad */
	NULL,			/* select - default */
	smb_ioctl,		/* ioctl */
#ifdef NO_MM
	NULL,                   /* mmap - we skip this support in NO_MM */
#else
	smb_mmap,		/* mmap */
#endif
	NULL,			/* open */
	NULL,			/* release */
	smb_fsync,		/* fsync */
};

struct inode_operations smb_file_inode_operations =
{
	&smb_file_operations,	/* default file operations */
	NULL,			/* create */
	NULL,			/* lookup */
	NULL,			/* link */
	NULL,			/* unlink */
	NULL,			/* symlink */
	NULL,			/* mkdir */
	NULL,			/* rmdir */
	NULL,			/* mknod */
	NULL,			/* rename */
	NULL,			/* readlink */
	NULL,			/* follow_link */
	NULL,			/* readpage */
	NULL,			/* writepage */
	NULL,			/* bmap */
	NULL			/* truncate */
};