btrfs: headers cleanup to remove unnecessary local includes

[BUG]
When I tried to remove btrfs_bio::fs_info and use btrfs_bio::inode to
grab the fs_info, the header "btrfs_inode.h" is needed to access the
full btrfs_inode structure.

Then btrfs will fail to compile.

[CAUSE]
There is a recursive including chain:

  "bio.h" -> "btrfs_inode.h" -> "extent_map.h" -> "compression.h" ->
  "bio.h"

That recursive including is causing problems for btrfs.

[ENHANCEMENT]
To reduce the risk of recursive including:

- Remove unnecessary local includes from btrfs headers
  Either the included header is pulled in by other headers, or is
  completely unnecessary.

- Remove btrfs local includes if the header only requires a pointer
  In that case let the implementing C file to pull the required header.

  This is especially important for headers like "btrfs_inode.h" which
  pulls in a lot of other btrfs headers, thus it's a mine field of
  recursive including.

- Remove unnecessary temporary structure definition
  Either if we have included the header defining the structure, or
  completely unused.

Now including "btrfs_inode.h" inside "bio.h" is completely fine,
although "btrfs_inode.h" still includes "extent_map.h", but that header
only includes "fs.h", no more chain back to "bio.h".

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/accessors.h

@@ -12,6 +12,7 @@
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <uapi/linux/btrfs_tree.h>
+#include "fs.h"
 #include "extent_io.h"
 
 struct extent_buffer;

fs/btrfs/btrfs_inode.h

@@ -18,20 +18,20 @@
 #include <linux/lockdep.h>
 #include <uapi/linux/btrfs_tree.h>
 #include <trace/events/btrfs.h>
+#include "ctree.h"
 #include "block-rsv.h"
 #include "extent_map.h"
-#include "extent_io.h"
 #include "extent-io-tree.h"
-#include "ordered-data.h"
-#include "delayed-inode.h"
 
-struct extent_state;
 struct posix_acl;
 struct iov_iter;
 struct writeback_control;
 struct btrfs_root;
 struct btrfs_fs_info;
 struct btrfs_trans_handle;
+struct btrfs_bio;
+struct btrfs_file_extent;
+struct btrfs_delayed_node;
 
 /*
  * Since we search a directory based on f_pos (struct dir_context::pos) we have

fs/btrfs/compression.h

@@ -14,14 +14,11 @@
 #include <linux/pagemap.h>
 #include "bio.h"
 #include "fs.h"
-#include "messages.h"
 
 struct address_space;
-struct page;
 struct inode;
 struct btrfs_inode;
 struct btrfs_ordered_extent;
-struct btrfs_bio;
 
 /*
  * We want to make sure that amount of RAM required to uncompress an extent is

fs/btrfs/ctree.h

@@ -17,9 +17,7 @@
 #include <linux/refcount.h>
 #include <uapi/linux/btrfs_tree.h>
 #include "locking.h"
-#include "fs.h"
 #include "accessors.h"
-#include "extent-io-tree.h"
 
 struct extent_buffer;
 struct btrfs_block_rsv;

fs/btrfs/defrag.c

@@ -15,6 +15,7 @@
 #include "defrag.h"
 #include "file-item.h"
 #include "super.h"
+#include "compression.h"
 
 static struct kmem_cache *btrfs_inode_defrag_cachep;
 

fs/btrfs/dir-item.c

@@ -9,6 +9,7 @@
 #include "transaction.h"
 #include "accessors.h"
 #include "dir-item.h"
+#include "delayed-inode.h"
 
 /*
  * insert a name into a directory, doing overflow properly if there is a hash

fs/btrfs/direct-io.c

@@ -10,6 +10,8 @@
 #include "fs.h"
 #include "transaction.h"
 #include "volumes.h"
+#include "bio.h"
+#include "ordered-data.h"
 
 struct btrfs_dio_data {
 	ssize_t submitted;

fs/btrfs/disk-io.c

@@ -50,6 +50,7 @@
 #include "relocation.h"
 #include "scrub.h"
 #include "super.h"
+#include "delayed-inode.h"
 
 #define BTRFS_SUPER_FLAG_SUPP	(BTRFS_HEADER_FLAG_WRITTEN |\
 				 BTRFS_HEADER_FLAG_RELOC |\

fs/btrfs/disk-io.h

@@ -9,7 +9,8 @@
 #include <linux/sizes.h>
 #include <linux/compiler_types.h>
 #include "ctree.h"
-#include "fs.h"
+#include "bio.h"
+#include "ordered-data.h"
 
 struct block_device;
 struct super_block;

fs/btrfs/extent-tree.c

@@ -40,6 +40,7 @@
 #include "orphan.h"
 #include "tree-checker.h"
 #include "raid-stripe-tree.h"
+#include "delayed-inode.h"
 
 #undef SCRAMBLE_DELAYED_REFS