• Chao Yu's avatar
    f2fs: enhance on-disk inode structure scalability · 7a2af766
    Chao Yu authored
    This patch add new flag F2FS_EXTRA_ATTR storing in inode.i_inline
    to indicate that on-disk structure of current inode is extended.
    
    In order to extend, we changed the inode structure a bit:
    
    Original one:
    
    struct f2fs_inode {
    	...
    	struct f2fs_extent i_ext;
    	__le32 i_addr[DEF_ADDRS_PER_INODE];
    	__le32 i_nid[DEF_NIDS_PER_INODE];
    }
    
    Extended one:
    
    struct f2fs_inode {
            ...
            struct f2fs_extent i_ext;
    	union {
    		struct {
    			__le16 i_extra_isize;
    			__le16 i_padding;
    			__le32 i_extra_end[0];
    		};
    		__le32 i_addr[DEF_ADDRS_PER_INODE];
    	};
            __le32 i_nid[DEF_NIDS_PER_INODE];
    }
    
    Once F2FS_EXTRA_ATTR is set, we will steal four bytes in the head of
    i_addr field for storing i_extra_isize and i_padding. with i_extra_isize,
    we can calculate actual size of reserved space in i_addr, available
    attribute fields included in total extra attribute fields for current
    inode can be described as below:
    
      +--------------------+
      | .i_mode            |
      | ...                |
      | .i_ext             |
      +--------------------+
      | .i_extra_isize     |-----+
      | .i_padding         |     |
      | .i_prjid           |     |
      | .i_atime_extra     |     |
      | .i_ctime_extra     |     |
      | .i_mtime_extra     |<----+
      | .i_inode_cs        |<----- store blkaddr/inline from here
      | .i_xattr_cs        |
      | ...                |
      +--------------------+
      |                    |
      |    block address   |
      |                    |
      +--------------------+
      | .i_nid             |
      +--------------------+
      |   node_footer      |
      | (nid, ino, offset) |
      +--------------------+
    
    Hence, with this patch, we would enhance scalability of f2fs inode for
    storing more newly added attribute.
    Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
    Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
    7a2af766
file.c 58.8 KB