f2fs: enhance on-disk inode structure scalability

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: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 060b1c5b0836..0c79ddd40b70 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -186,6 +186,8 @@ struct f2fs_extent {
 #define F2FS_NAME_LEN		255
 #define F2FS_INLINE_XATTR_ADDRS	50	/* 200 bytes for inline xattrs */
 #define DEF_ADDRS_PER_INODE	923	/* Address Pointers in an Inode */
+#define CUR_ADDRS_PER_INODE(inode)	(DEF_ADDRS_PER_INODE - \
+					get_extra_isize(inode))
 #define DEF_NIDS_PER_INODE	5	/* Node IDs in an Inode */
 #define ADDRS_PER_INODE(inode)	addrs_per_inode(inode)
 #define ADDRS_PER_BLOCK		1018	/* Address Pointers in a Direct Block */
@@ -205,6 +207,7 @@ struct f2fs_extent {
 #define F2FS_INLINE_DENTRY	0x04	/* file inline dentry flag */
 #define F2FS_DATA_EXIST		0x08	/* file inline data exist flag */
 #define F2FS_INLINE_DOTS	0x10	/* file having implicit dot dentries */
+#define F2FS_EXTRA_ATTR		0x20	/* file having extra attribute */
 
 struct f2fs_inode {
 	__le16 i_mode;			/* file mode */
@@ -232,8 +235,14 @@ struct f2fs_inode {
 
 	struct f2fs_extent i_ext;	/* caching a largest extent */
 
-	__le32 i_addr[DEF_ADDRS_PER_INODE];	/* Pointers to data blocks */
-
+	union {
+		struct {
+			__le16 i_extra_isize;	/* extra inode attribute size */
+			__le16 i_padding;	/* padding */
+			__le32 i_extra_end[0];	/* for attribute size calculation */
+		};
+		__le32 i_addr[DEF_ADDRS_PER_INODE];	/* Pointers to data blocks */
+	};
 	__le32 i_nid[DEF_NIDS_PER_INODE];	/* direct(2), indirect(2),
 						double_indirect(1) node id */
 } __packed;