namei.c

elinux jffs初始版本 具体了解JFFS的文件系统！

	de->start = 0;
	de->starthi = 0;
	fat_date_unix2dos(dir->i_mtime,&de->time,&de->date);
	de->ctime_ms = 0;
	de->ctime = de->time;
	de->adate = de->cdate = de->date;
	de->size = 0;
	fat_mark_buffer_dirty(sb, bh, 1);
	if ((dot = iget(dir->i_sb,ino)) != NULL)
		vfat_read_inode(dot);
	if (!dot) return -EIO;
	dot->i_mtime = dot->i_atime = CURRENT_TIME;
	dot->i_dirt = 1;
	if (isdot) {
		dot->i_size = dir->i_size;
		MSDOS_I(dot)->i_start = MSDOS_I(dir)->i_start;
		MSDOS_I(dot)->i_logstart = MSDOS_I(dir)->i_logstart;
		dot->i_nlink = dir->i_nlink;
	} else {
		dot->i_size = parent->i_size;
		MSDOS_I(dot)->i_start = MSDOS_I(parent)->i_start;
		MSDOS_I(dot)->i_logstart = MSDOS_I(parent)->i_logstart;
		dot->i_nlink = parent->i_nlink;
	}

	iput(dot);

	PRINTK(("vfat_create_a_dotdir 2\n"));
	return 0;
}

static int vfat_create_dotdirs(struct inode *dir, struct inode *parent)
{
	struct super_block *sb = dir->i_sb;
	int res;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	loff_t offset;

	PRINTK(("vfat_create_dotdirs 1\n"));
	if ((res = fat_add_cluster(dir)) < 0) return res;

	PRINTK(("vfat_create_dotdirs 2\n"));
	offset = 0;
	bh = NULL;
	if ((res = fat_get_entry(dir,&offset,&bh,&de)) < 0) return res;
	
	PRINTK(("vfat_create_dotdirs 3\n"));
	res = vfat_create_a_dotdir(dir, parent, bh, de, res, MSDOS_DOT, 1);
	PRINTK(("vfat_create_dotdirs 4\n"));
	if (res < 0) {
		fat_brelse(sb, bh);
		return res;
	}
	PRINTK(("vfat_create_dotdirs 5\n"));

	if ((res = fat_get_entry(dir,&offset,&bh,&de)) < 0) {
		fat_brelse(sb, bh);
		return res;
	}
	PRINTK(("vfat_create_dotdirs 6\n"));

	res = vfat_create_a_dotdir(dir, parent, bh, de, res, MSDOS_DOTDOT, 0);
	PRINTK(("vfat_create_dotdirs 7\n"));
	fat_brelse(sb, bh);

	return res;
}

/***** See if directory is empty */
static int vfat_empty(struct inode *dir)
{
	struct super_block *sb = dir->i_sb;
	loff_t pos;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;

	if (dir->i_count > 1)
		return -EBUSY;
	if (MSDOS_I(dir)->i_start) { /* may be zero in mkdir */
		pos = 0;
		bh = NULL;
		while (fat_get_entry(dir,&pos,&bh,&de) > -1) {
			/* Skip extended filename entries */
			if (de->attr == ATTR_EXT) continue;

			if (!IS_FREE(de->name) && strncmp(de->name,MSDOS_DOT,
			    MSDOS_NAME) && strncmp(de->name,MSDOS_DOTDOT,
			    MSDOS_NAME)) {
				fat_brelse(sb, bh);
				return -ENOTEMPTY;
			}
		}
		if (bh)
			fat_brelse(sb, bh);
	}
	return 0;
}

static int vfat_rmdir_free_ino(struct inode *dir,struct buffer_head *bh,
     struct msdos_dir_entry *de,int ino)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode;
	int res;

	if (ino < 0) return -EINVAL;
	if (!(inode = iget(dir->i_sb,ino))) return -ENOENT;
	if (!S_ISDIR(inode->i_mode)) {
		iput(inode);
		return -ENOTDIR;
	}
	if (dir->i_dev != inode->i_dev || dir == inode) {
		iput(inode);
		return -EBUSY;
	}
	res = vfat_empty(inode);
	if (res) {
		iput(inode);
		return res;
	}
	inode->i_nlink = 0;
	inode->i_mtime = dir->i_mtime = CURRENT_TIME;
	inode->i_atime = dir->i_atime = CURRENT_TIME;
	dir->i_nlink--;
	inode->i_dirt = dir->i_dirt = 1;
	de->name[0] = DELETED_FLAG;
	fat_mark_buffer_dirty(sb, bh, 1);
	iput(inode);

	return 0;
}

static int vfat_unlink_free_ino(struct inode *dir,struct buffer_head *bh,
     struct msdos_dir_entry *de,int ino,int nospc)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode;
	if (!(inode = iget(dir->i_sb,ino))) return -ENOENT;
	if ((!S_ISREG(inode->i_mode) && nospc) || IS_IMMUTABLE(inode)) {
		iput(inode);
		return -EPERM;
	}
	inode->i_nlink = 0;
	inode->i_mtime = dir->i_mtime = CURRENT_TIME;
	inode->i_atime = dir->i_atime = CURRENT_TIME;
	dir->i_version = ++event;
	MSDOS_I(inode)->i_busy = 1;
	inode->i_dirt = dir->i_dirt = 1;
	de->name[0] = DELETED_FLAG;
	fat_mark_buffer_dirty(sb, bh, 1);

	iput(inode);
	return 0;
}

static int vfat_remove_entry(struct inode *dir,struct slot_info *sinfo,
     struct buffer_head **bh,struct msdos_dir_entry **de,
     int is_dir,int nospc)
{
	struct super_block *sb = dir->i_sb;
	loff_t offset;
	int res, i;

	/* remove the shortname */
	offset = sinfo->shortname_offset;
	res = fat_get_entry(dir, &offset, bh, de);
	if (res < 0) return res;
	if (is_dir) {
		res = vfat_rmdir_free_ino(dir,*bh,*de,res);
	} else {
		res = vfat_unlink_free_ino(dir,*bh,*de,res,nospc);
	}
	if (res < 0) return res;
		
	/* remove the longname */
	offset = sinfo->longname_offset;
	for (i = sinfo->long_slots; i > 0; --i) {
		res = fat_get_entry(dir, &offset, bh, de);
		if (res < 0) {
			printk("vfat_remove_entry: problem 1\n");
			continue;
		}
		(*de)->name[0] = DELETED_FLAG;
		(*de)->attr = 0;
		fat_mark_buffer_dirty(sb, *bh, 1);
	}
	return 0;
}


static int vfat_rmdirx(struct inode *dir,const char *name,int len)
{
	struct super_block *sb = dir->i_sb;
	int res;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	struct slot_info sinfo;

	bh = NULL;
	res = -EPERM;
	if (name[0] == '.' && (len == 1 || (len == 2 && name[1] == '.')))
		goto rmdir_done;
	res = vfat_find(dir,name,len,1,0,0,&sinfo);

	if (res >= 0 && sinfo.total_slots > 0) {
		res = vfat_remove_entry(dir,&sinfo,&bh,&de,1,0);
		if (res > 0) {
			res = 0;
		}
		dir->i_version = ++event;
	}

rmdir_done:
	fat_brelse(sb, bh);
	return res;
}

/***** Remove a directory */
int vfat_rmdir(struct inode *dir,const char *name,int len)
{
	int res;

	res = vfat_rmdirx(dir, name, len);
	iput(dir);
	return res;
}

static int vfat_unlinkx(
	struct inode *dir,
	const char *name,
	int len,
	int nospc)	/* Flag special file ? */
{
	struct super_block *sb = dir->i_sb;
	int res;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	struct slot_info sinfo;

	bh = NULL;
	res = vfat_find(dir,name,len,1,0,0,&sinfo);

	if (res >= 0 && sinfo.total_slots > 0) {
		res = vfat_remove_entry(dir,&sinfo,&bh,&de,0,nospc);
		if (res > 0) {
			res = 0;
		}
	}

	fat_brelse(sb, bh);
	return res;
}


int vfat_mkdir(struct inode *dir,const char *name,int len,int mode)
{
	struct inode *inode;
	int res;

	fat_lock_creation();
	if ((res = vfat_create_entry(dir,name,len,1,&inode)) < 0) {
		fat_unlock_creation();
		iput(dir);
		return res;
	}

	dir->i_nlink++;
	inode->i_nlink = 2; /* no need to mark them dirty */
	MSDOS_I(inode)->i_busy = 1; /* prevent lookups */

	res = vfat_create_dotdirs(inode, dir);
	fat_unlock_creation();
	MSDOS_I(inode)->i_busy = 0;
	iput(inode);
	iput(dir);
	if (res < 0) {
		if (vfat_rmdir(dir,name,len) < 0)
			fat_fs_panic(dir->i_sb,"rmdir in mkdir failed");
	}
	return res;
}

/***** Unlink, as called for msdosfs */
int vfat_unlink(struct inode *dir,const char *name,int len)
{
	int res;

	res = vfat_unlinkx (dir,name,len,1);
	iput(dir);
	return res;
}

/***** Unlink, as called for uvfatfs */
int vfat_unlink_uvfat(struct inode *dir,const char *name,int len)
{
	int res;

	res = vfat_unlinkx (dir,name,len,0);
	iput(dir);
	return res;
}
 
int vfat_rename(struct inode *old_dir,const char *old_name,int old_len,
	struct inode *new_dir,const char *new_name,int new_len,int must_be_dir)
{
	struct super_block *sb = old_dir->i_sb;
	struct buffer_head *old_bh,*new_bh,*dotdot_bh;
	struct msdos_dir_entry *old_de,*new_de,*dotdot_de;
	loff_t old_offset,new_offset,old_longname_offset;
	int old_slots,old_ino,new_ino,dotdot_ino,ino;
	struct inode *old_inode, *new_inode, *dotdot_inode, *walk;
	int res, is_dir, i;
	int locked = 0;
	struct slot_info sinfo;

	PRINTK(("vfat_rename 1\n"));
	if (old_dir == new_dir && old_len == new_len &&
	    strncmp(old_name, new_name, old_len) == 0)
		return 0;

	old_bh = new_bh = NULL;
	old_inode = new_inode = NULL;
	res = vfat_find(old_dir,old_name,old_len,1,0,0,&sinfo);
	PRINTK(("vfat_rename 2\n"));
	if (res < 0) goto rename_done;

	old_slots = sinfo.total_slots;
	old_longname_offset = sinfo.longname_offset;
	old_offset = sinfo.shortname_offset;
	old_ino = sinfo.ino;
	res = fat_get_entry(old_dir, &old_offset, &old_bh, &old_de);
	PRINTK(("vfat_rename 3\n"));
	if (res < 0) goto rename_done;

	res = -ENOENT;
	if (!(old_inode = iget(old_dir->i_sb,old_ino)))
		goto rename_done;
	is_dir = S_ISDIR(old_inode->i_mode);
	if (must_be_dir && !is_dir)
		goto rename_done;
	if (is_dir) {
		if ((old_dir->i_dev != new_dir->i_dev) ||
		    (old_ino == new_dir->i_ino)) {
			res = -EINVAL;
			goto rename_done;
		}
		if (!(walk = iget(new_dir->i_sb,new_dir->i_ino))) return -EIO;
		/* prevent moving directory below itself */
		while (walk->i_ino != MSDOS_ROOT_INO) {
			ino = fat_parent_ino(walk,1);
			iput(walk);
			if (ino < 0) {
				res = ino;
				goto rename_done;
			}
			if (ino == old_ino) {
				res = -EINVAL;
				goto rename_done;
			}
			if (!(walk = iget(new_dir->i_sb,ino))) {
				res = -EIO;
				goto rename_done;
			}
		}
		iput(walk);
	}

	res = vfat_find(new_dir,new_name,new_len,1,0,is_dir,&sinfo);

	PRINTK(("vfat_rename 4\n"));
	if (res > -1) {
		int new_is_dir;

		PRINTK(("vfat_rename 5\n"));
		/* Filename currently exists.  Need to delete it */
		new_offset = sinfo.shortname_offset;
		res = fat_get_entry(new_dir, &new_offset, &new_bh, &new_de);
		PRINTK(("vfat_rename 6\n"));
		if (res < 0) goto rename_done;

		if (!(new_inode = iget(new_dir->i_sb,res)))
			goto rename_done;
		new_is_dir = S_ISDIR(new_inode->i_mode);
		iput(new_inode);
		if (new_is_dir) {
			PRINTK(("vfat_rename 7\n"));
			res = vfat_rmdirx(new_dir,new_name,new_len);
			PRINTK(("vfat_rename 8\n"));
			if (res < 0) goto rename_done;
		} else {
			/* Is this the same file, different case? */
			if (new_inode != old_inode) {
				PRINTK(("vfat_rename 9\n"));
				res = vfat_unlinkx(new_dir,new_name,new_len,1);
				PRINTK(("vfat_rename 10\n"));
				if (res < 0) goto rename_done;
			}
		}
	}

	PRINTK(("vfat_rename 11\n"));
	fat_lock_creation(); locked = 1;
	res = vfat_find(new_dir,new_name,new_len,1,1,is_dir,&sinfo);

	PRINTK(("vfat_rename 12\n"));
	if (res < 0) goto rename_done;

	new_offset = sinfo.shortname_offset;
	new_ino = sinfo.ino;
	res = fat_get_entry(new_dir, &new_offset, &new_bh, &new_de);
	PRINTK(("vfat_rename 13\n"));
	if (res < 0) goto rename_done;

	new_de->attr = old_de->attr;
	new_de->time = old_de->time;
	new_de->date = old_de->date;
	new_de->ctime_ms = old_de->ctime_ms;
	new_de->cdate = old_de->cdate;
	new_de->adate = old_de->adate;
	new_de->start = old_de->start;
	new_de->starthi = old_de->starthi;
	new_de->size = old_de->size;

	if (!(new_inode = iget(new_dir->i_sb,new_ino))) goto rename_done;
	PRINTK(("vfat_rename 14\n"));

	/* At this point, we have the inodes of the old file and the
	 * new file.  We need to transfer all information from the old
	 * inode to the new inode and then delete the slots of the old
	 * entry
	 */

	vfat_read_inode(new_inode);
	MSDOS_I(old_inode)->i_busy = 1;
	MSDOS_I(old_inode)->i_linked = new_inode;
	MSDOS_I(new_inode)->i_oldlink = old_inode;
	fat_cache_inval_inode(old_inode);
	PRINTK(("vfat_rename 15: old_slots=%d\n",old_slots));
	old_inode->i_dirt = 1;
	old_dir->i_version = ++event;

	/* remove the old entry */
	for (i = old_slots; i > 0; --i) {
		res = fat_get_entry(old_dir, &old_longname_offset, &old_bh, &old_de);
		if (res < 0) {
			printk("vfat_unlinkx: problem 1\n");
			continue;
		}
		old_de->name[0] = DELETED_FLAG;
		old_de->attr = 0;
		fat_mark_buffer_dirty(sb, old_bh, 1);
	}
	PRINTK(("vfat_rename 15b\n"));

	fat_mark_buffer_dirty(sb, new_bh, 1);
	dcache_add(new_dir, new_name, new_len, new_ino);

	/* XXX: There is some code in the original MSDOS rename that
	 * is not duplicated here and it might cause a problem in
	 * certain circumstances.
	 */
	
	if (S_ISDIR(old_inode->i_mode)) {
		if ((res = fat_scan(old_inode,MSDOS_DOTDOT,&dotdot_bh,
		    &dotdot_de,&dotdot_ino,SCAN_ANY)) < 0) goto rename_done;
		if (!(dotdot_inode = iget(old_inode->i_sb,dotdot_ino))) {
			fat_brelse(sb, dotdot_bh);
			res = -EIO;
			goto rename_done;
		}
		MSDOS_I(dotdot_inode)->i_start = MSDOS_I(new_dir)->i_start;
		MSDOS_I(dotdot_inode)->i_logstart = MSDOS_I(new_dir)->i_logstart;
		dotdot_de->start = CT_LE_W(MSDOS_I(new_dir)->i_logstart);
		dotdot_de->starthi = CT_LE_W((MSDOS_I(new_dir)->i_logstart) >> 16);
		dotdot_inode->i_dirt = 1;
		fat_mark_buffer_dirty(sb, dotdot_bh, 1);
		old_dir->i_nlink--;
		new_dir->i_nlink++;
		/* no need to mark them dirty */
		dotdot_inode->i_nlink = new_dir->i_nlink;
		iput(dotdot_inode);
		fat_brelse(sb, dotdot_bh);
	}

	if (res > 0) res = 0;

rename_done:
	if (locked)
		fat_unlock_creation();
	if (old_bh)
		fat_brelse(sb, old_bh);
	if (new_bh)
		fat_brelse(sb, new_bh);
	if (old_inode)
		iput(old_inode);
	iput(old_dir);
	iput(new_dir);
	return res;
}



/* Public inode operations for the VFAT fs */
struct inode_operations vfat_dir_inode_operations = {
	&fat_dir_operations,	/* default directory file-ops */
	vfat_create,		/* create */
	vfat_lookup,		/* lookup */
	NULL,			/* link */
	vfat_unlink,		/* unlink */
	NULL,			/* symlink */
	vfat_mkdir,		/* mkdir */
	vfat_rmdir,		/* rmdir */
	NULL,			/* mknod */
	vfat_rename,		/* rename */
	NULL,			/* readlink */
	NULL,			/* follow_link */
	NULL,			/* readpage */
	NULL,			/* writepage */
	fat_bmap,		/* bmap */
	NULL,			/* truncate */
	NULL			/* permission */
};


void vfat_read_inode(struct inode *inode)
{
	fat_read_inode(inode, &vfat_dir_inode_operations);
}

#ifdef MODULE
int init_module(void)
{
	return init_vfat_fs();
}


void cleanup_module(void)
{
	unregister_filesystem(&vfat_fs_type);
}

#endif /* ifdef MODULE */



/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 8
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -8
 * c-argdecl-indent: 8
 * c-label-offset: -8
 * c-continued-statement-offset: 8
 * c-continued-brace-offset: 0
 * End:
 */