btrfs: headers cleanup to remove unnecessary local includes

[ Upstream commit c5667f9c8eb90293dfa4e52c65eb89fe39f5652d ]

[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>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: b39b26e017c7 ("btrfs: zoned: don't zone append to conventional zone")
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
index 99b3ced12805..78721412951c 100644
--- a/fs/btrfs/accessors.h
+++ b/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;