[PATCH 10/20] btrfs: introduce extent allocation policy

[Naohiro Aota <naohiro.aota@xxxxxxx>]

This commit introduces extent allocation policy for btrfs. This policy
controls how btrfs allocate an extents from block groups.

There is no functional change introduced with this commit.

Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
 fs/btrfs/extent-tree.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 227d4d628b90..247d68eb4735 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3438,6 +3438,10 @@ btrfs_release_block_group(struct btrfs_block_group *cache,
 	btrfs_put_block_group(cache);
 }
 
+enum btrfs_extent_allocation_policy {
+	BTRFS_EXTENT_ALLOC_CLUSTERED,
+};
+
 /*
  * Structure used internally for find_free_extent() function.  Wraps needed
  * parameters.
@@ -3489,6 +3493,9 @@ struct find_free_extent_ctl {
 
 	/* Found result */
 	u64 found_offset;
+
+	/* Allocation policy */
+	enum btrfs_extent_allocation_policy policy;
 };
 
 
@@ -3826,6 +3833,7 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info,
 	ffe_ctl.have_caching_bg = false;
 	ffe_ctl.orig_have_caching_bg = false;
 	ffe_ctl.found_offset = 0;
+	ffe_ctl.policy = BTRFS_EXTENT_ALLOC_CLUSTERED;
 
 	ins->type = BTRFS_EXTENT_ITEM_KEY;
 	ins->objectid = 0;
-- 
2.25.0