namei.c

elinux jffs初始版本 具体了解JFFS的文件系统！

}

static loff_t vfat_find_free_slots(struct inode *dir,int slots)
{
	struct super_block *sb = dir->i_sb;
	loff_t offset, curr;
	struct msdos_dir_entry *de;
	struct buffer_head *bh;
	struct inode *inode;
	int ino;
	int row;
	int done;
	int res;
	int added;

	PRINTK(("vfat_find_free_slots: find %d free slots\n", slots));
	offset = curr = 0;
	bh = NULL;
	row = 0;
	ino = fat_get_entry(dir,&curr,&bh,&de);

	for (added = 0; added < 2; added++) {
		while (ino > -1) {
			done = IS_FREE(de->name);
			if (done) {
				inode = iget(sb,ino);
				if (inode) {
					/* Directory slots of busy deleted files aren't available yet. */
					done = !MSDOS_I(inode)->i_busy;
					/* PRINTK(("inode %d still busy\n", ino)); */
				}
				iput(inode);
			}
			if (done) {
				row++;
				if (row == slots) {
					fat_brelse(sb, bh);
					/* printk("----- Free offset at %d\n", offset); */
					return offset;
				}
			} else {
				row = 0;
				offset = curr;
			}
			ino = fat_get_entry(dir,&curr,&bh,&de);
		}

		if ((dir->i_ino == MSDOS_ROOT_INO) &&
		    (MSDOS_SB(sb)->fat_bits != 32)) 
			return -ENOSPC;
		if ((res = fat_add_cluster(dir)) < 0) return res;
		ino = fat_get_entry(dir,&curr,&bh,&de);
	}
	return -ENOSPC;
}

/* Translate a string, including coded sequences into Unicode */
static int
xlate_to_uni(const char *name, int len, char *outname, int *outlen,
	     int escape, int utf8, struct nls_table *nls)
{
	int i;
	const unsigned char *ip;
	char *op;
	int fill;
	unsigned char c1, c2, c3;

	if (utf8) {
		*outlen = utf8_mbstowcs((__u16 *) outname, name, PAGE_SIZE);
		if (name[len-1] == '.')
			*outlen-=2;
		op = &outname[*outlen * sizeof(__u16)];
	} else {
		if (name[len-1] == '.') 
			len--;
		op = outname;
		if (nls) {
			/* XXX: i is incorrectly computed. */
			for (i = 0, ip = name, op = outname, *outlen = 0;
			     i < len && *outlen <= 260; i++, *outlen += 1)
			{
				if (escape && (*ip == ':')) {
					if (i > len - 4) return -EINVAL;
					c1 = fat_esc2uni[ip[1]];
					c2 = fat_esc2uni[ip[2]];
					c3 = fat_esc2uni[ip[3]];
					if (c1 == 255 || c2 == 255 || c3 == 255)
						return -EINVAL;
					*op++ = (c1 << 4) + (c2 >> 2);
					*op++ = ((c2 & 0x3) << 6) + c3;
					ip += 4;
				} else {
					*op++ = nls->charset2uni[*ip].uni1;
					*op++ = nls->charset2uni[*ip].uni2;
					ip++;
				}
			}
		} else {
			for (i = 0, ip = name, op = outname, *outlen = 0;
			     i < len && *outlen <= 260; i++, *outlen += 1)
			{
				*op++ = *ip++;
				*op++ = 0;
			}
		}
	}
	if (*outlen > 260)
		return -ENAMETOOLONG;

	if (*outlen % 13) {
		*op++ = 0;
		*op++ = 0;
		*outlen += 1;
		if (*outlen % 13) {
			fill = 13 - (*outlen % 13);
			for (i = 0; i < fill; i++) {
				*op++ = 0xff;
				*op++ = 0xff;
			}
			*outlen += fill;
		}
	}

	return 0;
}

static int
vfat_fill_long_slots(struct msdos_dir_slot *ds, const char *name, int len,
		     char *msdos_name, int *slots,
		     int uni_xlate, int utf8, struct nls_table *nls)
{
	struct msdos_dir_slot *ps;
	struct msdos_dir_entry *de;
	int res;
	int slot;
	unsigned char cksum;
	char *uniname;
	const char *ip;
	unsigned long page;
	int unilen;
	int i;
	loff_t offset;

	if (name[len-1] == '.') len--;
	if(!(page = __get_free_page(GFP_KERNEL)))
		return -ENOMEM;
	uniname = (char *) page;
	res = xlate_to_uni(name, len, uniname, &unilen, uni_xlate, utf8, nls);
	if (res < 0) {
		free_page(page);
		return res;
	}

	*slots = unilen / 13;
	for (cksum = i = 0; i < 11; i++) {
		cksum = (((cksum&1)<<7)|((cksum&0xfe)>>1)) + msdos_name[i];
	}
	PRINTK(("vfat_fill_long_slots 3: slots=%d\n",*slots));

	for (ps = ds, slot = *slots; slot > 0; slot--, ps++) {
		int end, j;

		PRINTK(("vfat_fill_long_slots 4\n"));
		ps->id = slot;
		ps->attr = ATTR_EXT;
		ps->reserved = 0;
		ps->alias_checksum = cksum;
		ps->start = 0;
		PRINTK(("vfat_fill_long_slots 5: uniname=%s\n",uniname));
		offset = (slot - 1) * 26;
		ip = &uniname[offset];
		j = offset;
		end = 0;
		for (i = 0; i < 10; i += 2) {
			ps->name0_4[i] = *ip++;
			ps->name0_4[i+1] = *ip++;
		}
		PRINTK(("vfat_fill_long_slots 6\n"));
		for (i = 0; i < 12; i += 2) {
			ps->name5_10[i] = *ip++;
			ps->name5_10[i+1] = *ip++;
		}
		PRINTK(("vfat_fill_long_slots 7\n"));
		for (i = 0; i < 4; i += 2) {
			ps->name11_12[i] = *ip++;
			ps->name11_12[i+1] = *ip++;
		}
	}
	PRINTK(("vfat_fill_long_slots 8\n"));
	ds[0].id |= 0x40;

	de = (struct msdos_dir_entry *) ps;
	PRINTK(("vfat_fill_long_slots 9\n"));
	strncpy(de->name, msdos_name, MSDOS_NAME);

	free_page(page);
	return 0;
}
		
static int vfat_build_slots(struct inode *dir,const char *name,int len,
     struct msdos_dir_slot *ds, int *slots, int *is_long)
{
	struct msdos_dir_entry *de;
	char msdos_name[MSDOS_NAME];
	int res, xlate, utf8;
	struct nls_table *nls;

	PRINTK(("Entering vfat_build_slots: name=%s, len=%d\n", name, len));
	de = (struct msdos_dir_entry *) ds;
	xlate = MSDOS_SB(dir->i_sb)->options.unicode_xlate;
	utf8 = MSDOS_SB(dir->i_sb)->options.utf8;
	nls = MSDOS_SB(dir->i_sb)->nls_io;

	*slots = 1;
	*is_long = 0;
	if (len == 1 && name[0] == '.') {
		strncpy(de->name, MSDOS_DOT, MSDOS_NAME);
	} else if (len == 2 && name[0] == '.' && name[1] == '.') {
		strncpy(de->name, MSDOS_DOT, MSDOS_NAME);
	} else {
		PRINTK(("vfat_build_slots 4\n"));
		res = vfat_valid_shortname(name, len, 1, utf8);
		if (res > -1) {
			PRINTK(("vfat_build_slots 5a\n"));
			res = vfat_format_name(name, len, de->name, 1, utf8);
			PRINTK(("vfat_build_slots 5b\n"));
		} else {
			res = vfat_create_shortname(dir, name, len, msdos_name, utf8);
			if (res < 0) {
				return res;
			}

			res = vfat_valid_longname(name, len, 1, xlate);
			if (res < 0) {
				return res;
			}

			*is_long = 1;

			return vfat_fill_long_slots(ds, name, len, msdos_name,
						    slots, xlate, utf8, nls);
		}
	}
	return 0;
}

static int vfat_readdir_cb(
	filldir_t filldir,
	void * buf,
	const char * name,
	int name_len,
	int is_long,
	off_t offset,
	off_t short_offset,
	int long_slots,
	ino_t ino)
{
	struct vfat_find_info *vf = (struct vfat_find_info *) buf;
	const char *s1, *s2;
	int i;

#ifdef DEBUG
	if (debug) printk("cb: vf.name=%s, len=%d, name=%s, name_len=%d\n",
			  vf->name, vf->len, name, name_len);
#endif

	/* Filenames cannot end in '.' or we treat like it has none */
	if (vf->len != name_len) {
		if ((vf->len != name_len + 1) || (vf->name[name_len] != '.')) {
			return 0;
		}
	}

	s1 = name; s2 = vf->name;
	for (i = 0; i < name_len; i++) {
		if (vf->new_filename && !vf->posix) {
			if (tolower(*s1) != tolower(*s2))
				return 0;
		} else {
			if (*s1 != *s2)
				return 0;
		}
		s1++; s2++;
	}
	vf->found = 1;
	vf->is_long = is_long;
	vf->offset = (offset == 2) ? 0 : offset;
	vf->short_offset = (short_offset == 2) ? 0 : short_offset;
	vf->long_slots = long_slots;
	vf->ino = ino;
	return -1;
}

static int vfat_find(struct inode *dir,const char *name,int len,
    int find_long, int new_filename,int is_dir,struct slot_info *sinfo_out)
{
	struct super_block *sb = dir->i_sb;
	struct vfat_find_info vf;
	struct file fil;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	struct msdos_dir_slot *ps;
	loff_t offset;
	struct msdos_dir_slot *ds;
	int is_long;
	int slots, slot;
	int res;

	PRINTK(("Entering vfat_find\n"));

	ds = (struct msdos_dir_slot *)
	    kmalloc(sizeof(struct msdos_dir_slot)*MSDOS_SLOTS, GFP_KERNEL);
	if (ds == NULL) return -ENOMEM;

	fil.f_pos = 0;
	vf.name = name;
	vf.len = len;
	vf.new_filename = new_filename;
	vf.found = 0;
	vf.posix = MSDOS_SB(sb)->options.posixfs;
	res = fat_readdirx(dir,&fil,(void *)&vf,vfat_readdir_cb,NULL,1,find_long,0);
	PRINTK(("vfat_find: Debug 1\n"));
	if (res < 0) goto cleanup;
	if (vf.found) {
		if (new_filename) {
			res = -EEXIST;
			goto cleanup;
		}
		sinfo_out->longname_offset = vf.offset;
		sinfo_out->shortname_offset = vf.short_offset;
		sinfo_out->is_long = vf.is_long;
		sinfo_out->long_slots = vf.long_slots;
		sinfo_out->total_slots = vf.long_slots + 1;
		sinfo_out->ino = vf.ino;

		PRINTK(("vfat_find: Debug 2\n"));
		res = 0;
		goto cleanup;
	}

	PRINTK(("vfat_find: Debug 3\n"));
	if (!vf.found && !new_filename) {
		res = -ENOENT;
		goto cleanup;
	}
	
	res = vfat_build_slots(dir, name, len, ds, &slots, &is_long);
	if (res < 0) goto cleanup;

	de = (struct msdos_dir_entry *) ds;

	bh = NULL;
	if (new_filename) {
		PRINTK(("vfat_find: create file 1\n"));
		if (is_long) slots++;
		offset = vfat_find_free_slots(dir, slots);
		if (offset < 0) {
			res = offset;
			goto cleanup;
		}

		PRINTK(("vfat_find: create file 2\n"));
		/* Now create the new entry */
		bh = NULL;
		for (slot = 0, ps = ds; slot < slots; slot++, ps++) {
			PRINTK(("vfat_find: create file 3, slot=%d\n",slot));
			sinfo_out->ino = fat_get_entry(dir,&offset,&bh,&de);
			if (sinfo_out->ino < 0) {
				PRINTK(("vfat_find: problem\n"));
				res = sinfo_out->ino;
				goto cleanup;
			}
			memcpy(de, ps, sizeof(struct msdos_dir_slot));
			fat_mark_buffer_dirty(sb, bh, 1);
		}

		PRINTK(("vfat_find: create file 4\n"));
		dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
		dir->i_dirt = 1;

		PRINTK(("vfat_find: create file 5\n"));

		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->start = 0;
		de->starthi = 0;
		de->size = 0;
		de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
		de->lcase = CASE_LOWER_BASE | CASE_LOWER_EXT;


		fat_mark_buffer_dirty(sb, bh, 1);
		fat_brelse(sb, bh);

		sinfo_out->is_long = (slots > 1) ? 1 : 0;
		if (sinfo_out->is_long) {
			sinfo_out->long_slots = slots - 1;
		} else {
			sinfo_out->long_slots = 0;
		}
		sinfo_out->total_slots = slots;
		sinfo_out->shortname_offset = offset - sizeof(struct msdos_dir_slot);
		sinfo_out->longname_offset = offset - sizeof(struct msdos_dir_slot) * slots;
		res = 0;
		return 0;
	} else {
		res = -ENOENT;
	}

cleanup:
	kfree(ds);
	return res;
}

int vfat_lookup(struct inode *dir,const char *name,int len,
    struct inode **result)
{
	int res, ino;
	struct inode *next;
	struct slot_info sinfo;
	
	PRINTK (("vfat_lookup: name=%s, len=%d\n", name, len));

	*result = NULL;
	if (!dir) return -ENOENT;
	if (!S_ISDIR(dir->i_mode)) {
		iput(dir);
		return -ENOENT;
	}
	PRINTK (("vfat_lookup 2\n"));
	if (len == 1 && name[0] == '.') {
		*result = dir;
		return 0;
	}
	if (len == 2 && name[0] == '.' && name[1] == '.') {
		ino = fat_parent_ino(dir,0);
		iput(dir);
		if (ino < 0) return ino;
		if (!(*result = iget(dir->i_sb,ino))) return -EACCES;
		return 0;
	}
	if (dcache_lookup(dir, name, len, (unsigned long *) &ino) && ino) {
		iput(dir);
		if (!(*result = iget(dir->i_sb, ino)))
			return -EACCES;
		return 0;
	}
	PRINTK (("vfat_lookup 3\n"));
	if ((res = vfat_find(dir,name,len,1,0,0,&sinfo)) < 0) {
		iput(dir);
		return res;
	}
	PRINTK (("vfat_lookup 4.5\n"));
	if (!(*result = iget(dir->i_sb,sinfo.ino))) {
		iput(dir);
		return -EACCES;
	}
	PRINTK (("vfat_lookup 5\n"));
	if (!(*result)->i_sb ||
	    ((*result)->i_sb->s_magic != MSDOS_SUPER_MAGIC)) {
		/* crossed a mount point into a non-msdos fs */
		iput(dir);
		return 0;
	}
	if (MSDOS_I(*result)->i_busy) { /* mkdir in progress */
		iput(*result);
		iput(dir);
		return -ENOENT;
	}
	PRINTK (("vfat_lookup 6\n"));
	while (MSDOS_I(*result)->i_old) {
		next = MSDOS_I(*result)->i_old;
		iput(*result);
		if (!(*result = iget(next->i_sb,next->i_ino))) {
			fat_fs_panic(dir->i_sb,"vfat_lookup: Can't happen");
			iput(dir);
			return -ENOENT;
		}
	}
	iput(dir);
	return 0;
}


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

	PRINTK(("vfat_create_entry 1\n"));
	res = vfat_find(dir, name, len, 1, 1, is_dir, &sinfo);
	if (res < 0) {
		return res;
	}

	offset = sinfo.shortname_offset;

	PRINTK(("vfat_create_entry 2\n"));
	bh = NULL;
	ino = fat_get_entry(dir, &offset, &bh, &de);
	if (ino < 0) {
		PRINTK(("vfat_mkdir problem\n"));
		if (bh)
			fat_brelse(sb, bh);
		return ino;
	}
	PRINTK(("vfat_create_entry 3\n"));

	if ((*result = iget(dir->i_sb,ino)) != NULL)
		vfat_read_inode(*result);
	fat_brelse(sb, bh);
	if (!*result)
		return -EIO;
	(*result)->i_mtime = (*result)->i_atime = (*result)->i_ctime =
	    CURRENT_TIME;
	(*result)->i_dirt = 1;
	(*result)->i_version = ++event;
	dir->i_version = event;
	dcache_add(dir, name, len, ino);

	return 0;
}

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

	if (!dir) return -ENOENT;

	fat_lock_creation();
	res = vfat_create_entry(dir,name,len,0,result);
	if (res < 0) PRINTK(("vfat_create: unable to get new entry\n"));

	fat_unlock_creation();
	iput(dir);
	return res;
}

static int vfat_create_a_dotdir(struct inode *dir,struct inode *parent,
     struct buffer_head *bh,
     struct msdos_dir_entry *de,int ino,const char *name, int isdot)
{
	struct super_block *sb = dir->i_sb;
	struct inode *dot;

	PRINTK(("vfat_create_a_dotdir 1\n"));

	/*
	 * XXX all times should be set by caller upon successful completion.
	 */
	dir->i_atime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	dir->i_dirt = 1;
	memcpy(de->name,name,MSDOS_NAME);
	de->lcase = 0;
	de->attr = ATTR_DIR;