btrfs: better packing of btrfs_delayed_extent_op

btrfs_delayed_extent_op can be packed in a better way, it's 40 bytes now
and has 8 unused bytes. Reducing the level type to u8 makes it possible
to squeeze it to the padding byte after key. The bitfields were switched
to bool as there's space to store the full byte without increasing the
whole structure, besides that the generated assembly is smaller.

struct btrfs_delayed_extent_op {
	struct btrfs_disk_key      key;                  /*     0    17 */
	u8                         level;                /*    17     1 */
	bool                       update_key;           /*    18     1 */
	bool                       update_flags;         /*    19     1 */
	bool                       is_data;              /*    20     1 */

	/* XXX 3 bytes hole, try to pack */

	u64                        flags_to_set;         /*    24     8 */

	/* size: 32, cachelines: 1, members: 6 */
	/* sum members: 29, holes: 1, sum holes: 3 */
	/* last cacheline: 32 bytes */
};

The final size is 32 bytes which gives +26 object per slab page.

   text	   data	    bss	    dec	    hex	filename
 938811	  43670	  23144	1005625	  f5839	fs/btrfs/btrfs.ko.before
 938747	  43670	  23144	1005561	  f57f9	fs/btrfs/btrfs.ko.after

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

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index e06dd75ad13f98999682c00128ae852e0a886e14..914ac13bd92f2e34fd973d2e6da02708a7daa5d8 100644 (file)
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -493,12 +493,12 @@ update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
                                memcpy(&existing_ref->extent_op->key,
                                       &ref->extent_op->key,
                                       sizeof(ref->extent_op->key));
-                               existing_ref->extent_op->update_key = 1;
+                               existing_ref->extent_op->update_key = true;
                        }
                        if (ref->extent_op->update_flags) {
                                existing_ref->extent_op->flags_to_set |=
                                        ref->extent_op->flags_to_set;
-                               existing_ref->extent_op->update_flags = 1;
+                               existing_ref->extent_op->update_flags = true;
                        }
                        btrfs_free_delayed_extent_op(ref->extent_op);
                }

diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index 00ed02cbf3e903a708dd55a4c232a911241da2a8..c24b653c7343018a89931ef8344e0f71c2c1bf97 100644 (file)
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -75,11 +75,11 @@ struct btrfs_delayed_ref_node {
 
 struct btrfs_delayed_extent_op {
        struct btrfs_disk_key key;
+       u8 level;
+       bool update_key;
+       bool update_flags;
+       bool is_data;
        u64 flags_to_set;
-       int level;
-       unsigned int update_key:1;
-       unsigned int update_flags:1;
-       unsigned int is_data:1;
 };
 
 /*

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c4661db2b72ae4c412adaaecb7cbc236fbe1e7cf..d796b53850d0a9fa379372373dcd401191550531 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2988,9 +2988,9 @@ int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
                return -ENOMEM;
 
        extent_op->flags_to_set = flags;
-       extent_op->update_flags = 1;
-       extent_op->update_key = 0;
-       extent_op->is_data = is_data ? 1 : 0;
+       extent_op->update_flags = true;
+       extent_op->update_key = false;
+       extent_op->is_data = is_data ? true : false;
        extent_op->level = level;
 
        ret = btrfs_add_delayed_extent_op(root->fs_info, trans, bytenr,
@@ -7980,12 +7980,9 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
                else
                        memset(&extent_op->key, 0, sizeof(extent_op->key));
                extent_op->flags_to_set = flags;
-               if (skinny_metadata)
-                       extent_op->update_key = 0;
-               else
-                       extent_op->update_key = 1;
-               extent_op->update_flags = 1;
-               extent_op->is_data = 0;
+               extent_op->update_key = skinny_metadata ? false : true;
+               extent_op->update_flags = true;
+               extent_op->is_data = false;
                extent_op->level = level;
 
                ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,

diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h
deleted file mode 100644 (file)
index e69de29..0000000