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头文件
#define MAXLEN 8
#define MAX_FILES 32
#define MAX_BLOCKSIZE 512
// 定义每一个目录项的格式
struct dir_entry
{
char filename[MAXLEN];
uint8_t idx;
};
// 定义每一个文件的格式。
struct file_blk
{
uint8_t busy;
mode_t mode;
uint8_t idx;
union
{
uint8_t file_size;
uint8_t dir_children;
};
struct dir_entry data0[6];
char data[100];
};
源码
#include <linux>
#include <linux>
#include <linux>
#include <linux>
#include "tinyFs.h"
#define CURRENT_TIME (current_kernel_time())
struct file_blk block[MAX_FILES+1];
int curr_count = 0;// 我勒个去,竟然使用了全局变量!
// 获得一个尚未使用的文件块,保存新创建的文件或者目录
static int get_block(void)
{
int i;
// 就是一个遍历,但实现快速。
for (i =2;i
{
if(!block[i].busy)
{
memset(&block[i],0,sizeof(struct file_blk));
block[i].busy =1;
return i;
}
}
return -1;
}
static struct inode_operations tinyfs_inode_ops ;
// 读取目录的实现
static int tinyfs_readdir(struct file *filp, struct dir_context *ctx)
{
//return -EISDIR;
#if 1
loff_t pos;
struct file_blk *blk;
struct dir_entry *entry;
int i;
pos = filp->f_pos;
if(pos)
return 0;
blk =(struct file_blk *)filp->f_path.dentry->d_inode->i_private;
if(!S_ISDIR(blk->mode))
{
return -ENOTDIR;
}
// 循环获取一个目录的所有文件的文件名
dir_emit_dot(filp, ctx);
ctx->pos++;
dir_emit_dotdot(filp, ctx);
ctx->pos++;
entry =(struct dir_entry *)&blk->data0;
for (i = 0; i < blk->dir_children; i++)
{
//filldir(dirent, entry[i].filename, MAXLEN, pos, entry[i].idx,DT_UNKNOWN);
if(!dir_emit(ctx, entry[i].filename, MAXLEN,entry[i].idx, DT_UNKNOWN))
break;
ctx->pos++;
//filp->f_pos += sizeof(struct dir_entry);
// pos += sizeof(struct dir_entry);
}
return 0;
#endif
}
// read实现
ssize_t tinyfs_read(struct file * filp, char __user * buf, size_t len, loff_t *ppos)
{
struct file_blk *blk;
char *buffer;
blk = (struct file_blk *)filp->f_path.dentry->d_inode->i_private;
if(*ppos >= blk->file_size)
return 0;
buffer = (char *)&blk->data[0];
len = min((size_t) blk->file_size, len);
if (copy_to_user(buf, buffer, len)) {
return -EFAULT;
}
*ppos += len;
return len;
}
// write实现
ssize_t tinyfs_write(struct file * filp, const char __user * buf, size_t len, loff_t* ppos)
{
struct file_blk *blk;
char *buffer;
blk = filp->f_path.dentry->d_inode->i_private;
buffer =(char*)&blk->data[0];
buffer += *ppos;
if (copy_from_user(buffer, buf, len))
{
return -EFAULT;
}
*ppos += len;
blk->file_size = *ppos;
return len;
}
const struct file_operations tinyfs_file_operations = {
.read = tinyfs_read,
.write = tinyfs_write,
};
const struct file_operations tinyfs_dir_operations = {
.owner = THIS_MODULE,
.iterate = tinyfs_readdir,
};
// 创建文件的实现
static int tinyfs_do_create(struct inode *dir, struct dentry *dentry, umode_t mode)
{
struct inode *inode;
struct super_block *sb;
struct dir_entry *entry;
struct file_blk *blk, *pblk;
int idx;
sb = dir->i_sb;
if (curr_count >= MAX_FILES)
{
return -ENOSPC;
}
if (!S_ISDIR(mode) && !S_ISREG(mode))
{
return -EINVAL;
}
inode = new_inode(sb);
if (!inode){
return -ENOMEM;
}
inode->i_sb = sb;
inode->i_op = &tinyfs_inode_ops;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
idx = get_block();
// 获取一个空闲的文件块保存新文件
blk = &block[idx];
inode->i_ino =idx;
blk->mode = mode;
curr_count ++;
if (S_ISDIR(mode))
{
blk->dir_children = 0;
inode->i_fop = &tinyfs_dir_operations;
}
else if(S_ISREG(mode)) {
blk->file_size = 0;
inode->i_fop = &tinyfs_file_operations;
}
inode->i_private = blk;
pblk = (struct file_blk *)dir->i_private;
entry = (struct dir_entry *)&pblk->data0;
entry += pblk->dir_children;
pblk->dir_children ++;
entry->idx = idx;
memset(entry->filename, 0, MAXLEN);
strcpy(entry->filename, dentry->d_name.name);
// VFS穿针引线的关键步骤,将VFS的inode链接到链表
inode_init_owner(inode, dir, mode);
d_add(dentry, inode);
return 0;
}
static int tinyfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
return tinyfs_do_create(dir, dentry, S_IFDIR | mode);
}
static int tinyfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
{
return tinyfs_do_create(dir, dentry, mode);
}
static struct inode *tinyfs_iget(struct super_block *sb, int idx)
{
struct inode *inode;
struct file_blk *blk;
inode = new_inode(sb);
inode->i_ino = idx;
inode->i_sb = sb;
inode->i_op = &tinyfs_inode_ops;
blk = &block[idx];
if (S_ISDIR(blk->mode))
inode->i_fop = &tinyfs_dir_operations;
else if (S_ISREG(blk->mode))
inode->i_fop = &tinyfs_file_operations;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_private = blk;
return inode;
}
struct dentry *tinyfs_lookup(struct inode *parent_inode, struct dentry *
child_dentry, unsigned int flags)
{
struct super_block *sb = parent_inode->i_sb;
struct file_blk *blk;
struct dir_entry *entry;
int i;
blk = (struct file_blk *)parent_inode->i_private;
entry =(struct dir_entry *)&blk->data[0];
for(i =0; i < blk->dir_children; i++)
{
if (!strcmp(entry[i].filename, child_dentry->d_name.name))
{
struct inode *inode = tinyfs_iget(sb, entry[i].idx);
struct file_blk *inner = (struct file_blk *)inode->i_private;
inode_init_owner(inode, parent_inode, inner->mode);
d_add(child_dentry, inode);
return NULL;
}
}
return NULL;
}
int tinyfs_rmdir(struct inode *dir, struct dentry *dentry)
{
#if 0
struct inode *inode = dentry->d_inode;
struct file_blk *blk = (struct file_blk *)inode->i_private;
memset(blk, 0, sizeof(struct file_blk));
blk->busy = 0;
#endif
int i;
struct inode *inode = dentry->d_inode;
struct file_blk *blk = (struct file_blk *)inode->i_private;
struct file_blk *pblk = (struct file_blk *)dir->i_private;
struct dir_entry *entry;
// 更新其上层目录
entry = (struct dir_entry *)&pblk->data0;
for (i = 0; i < pblk->dir_children; i++)
{
if (!strcmp(entry[i].filename, dentry->d_name.name))
{
int j;
for (j = i; j < pblk->dir_children - 1; j++)
{
memcpy(&entry[j], &entry[j+1], sizeof(struct dir_entry));
}
pblk->dir_children --;
break;
}
}
blk->busy = 0;
return simple_rmdir(dir, dentry);
}
int tinyfs_unlink(struct inode *dir, struct dentry *dentry)
{
int i;
struct inode *inode = dentry->d_inode;
struct file_blk *blk = (struct file_blk *)inode->i_private;
struct file_blk *pblk = (struct file_blk *)dir->i_private;
struct dir_entry *entry;
// 更新其上层目录
entry = (struct dir_entry *)&pblk->data0;
for (i = 0; i < pblk->dir_children; i++)
{
if (!strcmp(entry[i].filename, dentry->d_name.name))
{
int j;
for (j = i; j < pblk->dir_children - 1; j++)
{
memcpy(&entry[j], &entry[j+1], sizeof(struct dir_entry));
}
pblk->dir_children --;
break;
}
}
blk->busy = 0;
return simple_unlink(dir, dentry);
}
static struct inode_operations tinyfs_inode_ops = {
.create = tinyfs_create,
.lookup = tinyfs_lookup,
.mkdir = tinyfs_mkdir,
.rmdir = tinyfs_rmdir,
.unlink = tinyfs_unlink,
};
int tinyfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *root_inode;
int mode = S_IFDIR;
root_inode = new_inode(sb);
root_inode->i_ino = 1;
inode_init_owner(root_inode, NULL, mode);
root_inode->i_sb = sb;
root_inode->i_op = &tinyfs_inode_ops;
root_inode->i_fop = &tinyfs_dir_operations;
root_inode->i_atime = root_inode->i_mtime = root_inode->i_ctime =CURRENT_TIME;
block[1].mode = mode;
block[1].dir_children = 0;
block[1].idx = 1;
block[1].busy = 1;
root_inode->i_private = &block[1];
sb->s_root = d_make_root(root_inode);
curr_count ++;
return 0;
}
static struct dentry *tinyfs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data)
{
return mount_nodev(fs_type, flags, data, tinyfs_fill_super);
}
static void tinyfs_kill_superblock(struct super_block *sb)
{
kill_anon_super(sb);
}
struct file_system_type tinyfs_fs_type = {
.owner = THIS_MODULE,
.name = "tinyfs",
.mount = tinyfs_mount,
.kill_sb = tinyfs_kill_superblock,
};
static int tinyfs_init(void)
{
int ret;
memset(block, 0, sizeof(block));
ret = register_filesystem(&tinyfs_fs_type);
if (ret)
printk("register tinyfs failed\\n");
return ret;
}
static void tinyfs_exit(void)
{
unregister_filesystem(&tinyfs_fs_type);
}
module_init(tinyfs_init);
module_exit(tinyfs_exit);
MODULE_LICENSE("GPL");
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