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, 8 insertions, 3 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 3e7efbe55..af66a3f3a 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -445,8 +445,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 	/* Will be used by directory only */
 	fi->i_dir_level = F2FS_SB(sb)->dir_level;
 
-	fi->i_inline_reserved = DEF_INLINE_RESERVED_SIZE;
-
 	return &fi->vfs_inode;
 }
 
@@ -1299,9 +1297,16 @@ static const struct export_operations f2fs_export_ops = {
 
 static loff_t max_file_blocks(void)
 {
-	loff_t result = (DEF_ADDRS_PER_INODE - F2FS_INLINE_XATTR_ADDRS);
+	loff_t result = 0;
 	loff_t leaf_count = ADDRS_PER_BLOCK;
 
+	/*
+	 * note: previously, result is equal to (DEF_ADDRS_PER_INODE -
+	 * F2FS_INLINE_XATTR_ADDRS), but now f2fs try to reserve more
+	 * space in inode.i_addr, it will be more safe to reassign
+	 * result as zero.
+	 */
+
 	/* two direct node blocks */
 	result += (leaf_count * 2);