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頭文件
#define MAXLEN 8
#define MAX_FILES 32
#define MAX_BLOCKSIZE 512
// 定義每一個目錄項的格式
struct dir_entry
{
char filename[MAXLEN];
uint8_t idx;
};
// 定義每一個文件的格式。
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];
};
源碼
#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;// 我勒個去，竟然使用了全局變量！
// 獲得一個尚未使用的文件塊，保存新創建的文件或者目錄
static int get_block(void)
{
int i;
// 就是一個遍歷，但實現快速。
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 ; // 讀取目錄的實現 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; } // 循環獲取一個目錄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實現 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實現 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, }; // 創建文件的實現 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(); // 獲取一個空閒的文件塊保存新文件 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穿針引線的關鍵步驟，將VFS的inode鏈接到鏈表 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; // 更新其上層目錄 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; // 更新其上層目錄 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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