[PATCH v2 4/7] btrfs: change block group reclaim_mark to bool

[Sun YangKai <sunk67188@gmail.com>]

The reclaim_mark field in struct btrfs_block_group was a u64 that was
incremented when marking block groups for reclaim during sweeping, but
the actual counter value was never used - only the zero/non-zero state
mattered for determining if a block group needed reclaim.

Convert it to a bool to properly reflect its usage and reduce memory
footprint by 8 bytes. Update assignments to use true/false instead of
increment and zero.

Now sizeof(struct btrfs_block_group) is 632->624.

Signed-off-by: Sun YangKai <sunk67188@gmail.com>
---
 fs/btrfs/block-group.c | 2 +-
 fs/btrfs/block-group.h | 7 ++++++-
 fs/btrfs/space-info.c  | 2 +-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 94a4068cd42a..f29553fa204a 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -3728,7 +3728,7 @@ int btrfs_update_block_group(struct btrfs_trans_handle *trans,
 		old_val += num_bytes;
 		cache->used = old_val;
 		cache->reserved -= num_bytes;
-		cache->reclaim_mark = 0;
+		cache->reclaim_mark = false;
 		space_info->bytes_reserved -= num_bytes;
 		space_info->bytes_used += num_bytes;
 		space_info->disk_used += num_bytes * factor;
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index 5f933455118c..3b3c61b3af2c 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -251,6 +251,12 @@ struct btrfs_block_group {
 	/* Protected by @free_space_lock. */
 	bool using_free_space_bitmaps_cached;
 
+	/*
+	 * Mark this blockgroup is not used for allocation
+	 * between two reclaim sweeps.
+	 */
+	bool reclaim_mark;
+
 	/*
 	 * Number of extents in this block group used for swap files.
 	 * All accesses protected by the spinlock 'lock'.
@@ -270,7 +276,6 @@ struct btrfs_block_group {
 	struct work_struct zone_finish_work;
 	struct extent_buffer *last_eb;
 	enum btrfs_block_group_size_class size_class;
-	u64 reclaim_mark;
 };
 
 static inline u64 btrfs_block_group_end(const struct btrfs_block_group *block_group)
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 3ccb365549ff..dce21809e640 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -2104,7 +2104,7 @@ static void do_reclaim_sweep(struct btrfs_space_info *space_info, int raid)
 			will_reclaim = true;
 			reclaim = true;
 		}
-		bg->reclaim_mark++;
+		bg->reclaim_mark = true;
 		spin_unlock(&bg->lock);
 		if (reclaim)
 			btrfs_mark_bg_to_reclaim(bg);
-- 
2.51.2