inode.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

 *
 * Given the MDB for a HFS filesystem, a 'key' and an 'entry' in
 * the catalog B-tree and the 'type' of the desired file return the
 * inode for that file/directory or NULL.  Note that 'type' indicates
 * whether we want the actual file or directory, or the corresponding
 * metadata (AppleDouble header file or CAP metadata file).
 *
 * In an ideal world we could call iget() and would not need this
 * function.  However, since there is no way to even know the inode
 * number until we've found the file/directory in the catalog B-tree
 * that simply won't happen.
 *
 * The main idea here is to look in the catalog B-tree to get the
 * vital info about the file or directory (including the file id which
 * becomes the inode number) and then to call iget() and return the
 * inode if it is complete.  If it is not then we use the catalog
 * entry to fill in the missing info, by calling the appropriate
 * 'fillin' function.  Note that these fillin functions are
 * essentially hfs_*_read_inode() functions, but since there is no way
 * to pass the catalog entry through iget() to such a read_inode()
 * function, we have to call them after iget() returns an incomplete
 * inode to us.	 This is pretty much the same problem faced in the NFS
 * code, and pretty much the same solution. The SMB filesystem deals
 * with this in a different way: by using the address of the
 * kmalloc()'d space which holds the data as the inode number.
 *
 * XXX: Both this function and NFS's corresponding nfs_fhget() would
 * benefit from a way to pass an additional (void *) through iget() to
 * the VFS read_inode() function.
 *
 * this will hfs_cat_put() the entry if it fails.
 */
struct inode *hfs_iget(struct hfs_cat_entry *entry, ino_t type,
		       struct dentry *dentry)
{
	struct dentry **sys_entry;
	struct super_block *sb;
	struct inode *inode;

	if (!entry) {
		return NULL;
	}

	/* If there are several processes all calling __iget() for
	   the same inode then they will all get the same one back.
	   The first one to return from __iget() will notice that the
	   i_mode field of the inode is blank and KNOW that it is
	   the first to return.  Therefore, it will set the appropriate
	   'sys_entry' field in the entry and initialize the inode.
	   All the initialization must be done without sleeping,
	   or else other processes could end up using a partially
	   initialized inode.				*/

	sb = entry->mdb->sys_mdb;
	sys_entry = &entry->sys_entry[HFS_ITYPE_TO_INT(type)];

	if (!(inode = iget(sb, ntohl(entry->cnid) | type))) {
	        hfs_cat_put(entry);
	        return NULL;
	}

	if (inode->i_dev != sb->s_dev) {
	        iput(inode); /* automatically does an hfs_cat_put */
		inode = NULL;
	} else if (!inode->i_mode || (*sys_entry == NULL)) {
		/* Initialize the inode */
		struct hfs_sb_info *hsb = HFS_SB(sb);

		inode->i_rdev = 0;
		inode->i_ctime = inode->i_atime = inode->i_mtime =
					hfs_m_to_utime(entry->modify_date);
		inode->i_blksize = HFS_SECTOR_SIZE;
		inode->i_uid = hsb->s_uid;
		inode->i_gid = hsb->s_gid;

		memset(HFS_I(inode), 0, sizeof(struct hfs_inode_info));
		HFS_I(inode)->magic = HFS_INO_MAGIC;
		HFS_I(inode)->entry = entry;
		HFS_I(inode)->tz_secondswest = hfs_to_utc(0);

		hsb->s_ifill(inode, type, hsb->s_version);
		if (!hsb->s_afpd && (entry->type == HFS_CDR_FIL) &&
		    (entry->u.file.flags & HFS_FIL_LOCK)) {
			inode->i_mode &= ~S_IWUGO;
		}
		inode->i_mode &= ~hsb->s_umask;

		if (!inode->i_mode) {
			iput(inode); /* does an hfs_cat_put */
			inode = NULL;
		} else
			*sys_entry = dentry; /* cache dentry */

	}

	return inode;
}

/*================ Scheme-specific functions ================*/

/* 
 * hfs_cap_ifill()
 *
 * This function serves the same purpose as a read_inode() function does
 * in other filesystems.  It is called by __hfs_iget() to fill in
 * the missing fields of an uninitialized inode under the CAP scheme.
 */
void hfs_cap_ifill(struct inode * inode, ino_t type, const int version)
{
	struct hfs_cat_entry *entry = HFS_I(inode)->entry;

	HFS_I(inode)->d_drop_op = hfs_cap_drop_dentry;
	if (type == HFS_CAP_FNDR) {
		inode->i_size = sizeof(struct hfs_cap_info);
		inode->i_blocks = 0;
		inode->i_nlink = 1;
		inode->i_mode = S_IRUGO | S_IWUGO | S_IFREG;
		inode->i_op = &hfs_cap_info_inode_operations;
		inode->i_fop = &hfs_cap_info_operations;
	} else if (entry->type == HFS_CDR_FIL) {
		init_file_inode(inode, (type == HFS_CAP_DATA) ?
						HFS_FK_DATA : HFS_FK_RSRC);
		inode->i_op = &hfs_file_inode_operations;
		inode->i_fop = &hfs_file_operations;
		inode->i_mapping->a_ops = &hfs_aops;
		inode->u.hfs_i.mmu_private = inode->i_size;
	} else { /* Directory */
		struct hfs_dir *hdir = &entry->u.dir;

		inode->i_blocks = 0;
		inode->i_size = hdir->files + hdir->dirs + 5;
		HFS_I(inode)->dir_size = 1;
		if (type == HFS_CAP_NDIR) {
			inode->i_mode = S_IRWXUGO | S_IFDIR;
			inode->i_nlink = hdir->dirs + 4;
			inode->i_op = &hfs_cap_ndir_inode_operations;
			inode->i_fop = &hfs_cap_dir_operations;
			HFS_I(inode)->file_type = HFS_CAP_NORM;
		} else if (type == HFS_CAP_FDIR) {
			inode->i_mode = S_IRUGO | S_IXUGO | S_IFDIR;
			inode->i_nlink = 2;
			inode->i_op = &hfs_cap_fdir_inode_operations;
			inode->i_fop = &hfs_cap_dir_operations;
			HFS_I(inode)->file_type = HFS_CAP_FNDR;
		} else if (type == HFS_CAP_RDIR) {
			inode->i_mode = S_IRUGO | S_IXUGO | S_IFDIR;
			inode->i_nlink = 2;
			inode->i_op = &hfs_cap_rdir_inode_operations;
			inode->i_fop = &hfs_cap_dir_operations;
			HFS_I(inode)->file_type = HFS_CAP_RSRC;
		}
	}
}

/* 
 * hfs_dbl_ifill()
 *
 * This function serves the same purpose as a read_inode() function does
 * in other filesystems.  It is called by __hfs_iget() to fill in
 * the missing fields of an uninitialized inode under the AppleDouble
 * scheme.
 */
void hfs_dbl_ifill(struct inode * inode, ino_t type, const int version)
{
	struct hfs_cat_entry *entry = HFS_I(inode)->entry;

	HFS_I(inode)->d_drop_op = hfs_dbl_drop_dentry;
	if (type == HFS_DBL_HDR) {
		if (entry->type == HFS_CDR_FIL) {
			init_file_inode(inode, HFS_FK_RSRC);
			inode->i_size += HFS_DBL_HDR_LEN;
			HFS_I(inode)->default_layout = &hfs_dbl_fil_hdr_layout;
		} else {
			inode->i_size = HFS_DBL_HDR_LEN;
			inode->i_mode = S_IRUGO | S_IWUGO | S_IFREG;
			inode->i_nlink = 1;
			HFS_I(inode)->default_layout = &hfs_dbl_dir_hdr_layout;
		}
		inode->i_op = &hfs_hdr_inode_operations;
		inode->i_fop = &hfs_hdr_operations;
	} else if (entry->type == HFS_CDR_FIL) {
		init_file_inode(inode, HFS_FK_DATA);
		inode->i_op = &hfs_file_inode_operations;
		inode->i_fop = &hfs_file_operations;
		inode->i_mapping->a_ops = &hfs_aops;
		inode->u.hfs_i.mmu_private = inode->i_size;
	} else { /* Directory */
		struct hfs_dir *hdir = &entry->u.dir;

		inode->i_blocks = 0;
		inode->i_nlink = hdir->dirs + 2;
		inode->i_size = 3 + 2 * (hdir->dirs + hdir->files);
		inode->i_mode = S_IRWXUGO | S_IFDIR;
		inode->i_op = &hfs_dbl_dir_inode_operations;
		inode->i_fop = &hfs_dbl_dir_operations;
		HFS_I(inode)->file_type = HFS_DBL_NORM;
		HFS_I(inode)->dir_size = 2;
	}
}

/* 
 * hfs_nat_ifill()
 *
 * This function serves the same purpose as a read_inode() function does
 * in other filesystems.  It is called by __hfs_iget() to fill in
 * the missing fields of an uninitialized inode under the Netatalk
 * scheme.
 */
void hfs_nat_ifill(struct inode * inode, ino_t type, const int version)
{
	struct hfs_cat_entry *entry = HFS_I(inode)->entry;

	HFS_I(inode)->d_drop_op = hfs_nat_drop_dentry;
	if (type == HFS_NAT_HDR) {
		if (entry->type == HFS_CDR_FIL) {
			init_file_inode(inode, HFS_FK_RSRC);
			inode->i_size += HFS_NAT_HDR_LEN;
		} else {
			inode->i_size = HFS_NAT_HDR_LEN;
			inode->i_mode = S_IRUGO | S_IWUGO | S_IFREG;
			inode->i_nlink = 1;
		}
		inode->i_op = &hfs_hdr_inode_operations;
		inode->i_fop = &hfs_hdr_operations;
		HFS_I(inode)->default_layout = (version == 2) ?
			&hfs_nat2_hdr_layout : &hfs_nat_hdr_layout;
	} else if (entry->type == HFS_CDR_FIL) {
		init_file_inode(inode, HFS_FK_DATA);
		inode->i_op = &hfs_file_inode_operations;
		inode->i_fop = &hfs_file_operations;
		inode->i_mapping->a_ops = &hfs_aops;
		inode->u.hfs_i.mmu_private = inode->i_size;
	} else { /* Directory */
		struct hfs_dir *hdir = &entry->u.dir;

		inode->i_blocks = 0;
		inode->i_size = hdir->files + hdir->dirs + 4;
		inode->i_mode = S_IRWXUGO | S_IFDIR;
		HFS_I(inode)->dir_size = 1;
		if (type == HFS_NAT_NDIR) {
			inode->i_nlink = hdir->dirs + 3;
			inode->i_op = &hfs_nat_ndir_inode_operations;
			HFS_I(inode)->file_type = HFS_NAT_NORM;
		} else if (type == HFS_NAT_HDIR) {
			inode->i_nlink = 2;
			inode->i_op = &hfs_nat_hdir_inode_operations;
			HFS_I(inode)->file_type = HFS_NAT_HDR;
		}
		inode->i_fop = &hfs_nat_dir_operations;
	}
}