ext4: move extra inode read to a new function

Currently, in ext4_iget we do a simple check to see whether
there does exist some information starting from the end
of i_extra_size. With inline data added, this procedure
is more complicated. So move it to a new function named
ext4_iget_extra_inode.
Signed-off-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -3700,6 +3700,16 @@ static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
 	}
 }
 
+static inline void ext4_iget_extra_inode(struct inode *inode,
+					 struct ext4_inode *raw_inode,
+					 struct ext4_inode_info *ei)
+{
+	__le32 *magic = (void *)raw_inode +
+			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
+	if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
+		ext4_set_inode_state(inode, EXT4_STATE_XATTR);
+}
+
 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 {
 	struct ext4_iloc iloc;
@@ -3842,11 +3852,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 			ei->i_extra_isize = sizeof(struct ext4_inode) -
 					    EXT4_GOOD_OLD_INODE_SIZE;
 		} else {
-			__le32 *magic = (void *)raw_inode +
-					EXT4_GOOD_OLD_INODE_SIZE +
-					ei->i_extra_isize;
-			if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
-				ext4_set_inode_state(inode, EXT4_STATE_XATTR);
+			ext4_iget_extra_inode(inode, raw_inode, ei);
 		}
 	}