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[PATCH] btrfs: make array types static const, reduces object code size

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  [PATCH] btrfs: make array types static const, reduces object code size Colin King <colin.king@canonical.com> - 2017-09-19 17:10 +0200
    Re: [PATCH] btrfs: make array types static const, reduces object  code size David Sterba <dsterba@suse.cz> - 2017-09-19 17:20 +0200

#1734996 — [PATCH] btrfs: make array types static const, reduces object code size

From: Colin Ian King <colin.king@canonical.com>

Don't populate the read-only array types on the stack, instead make
it static const.  Makes the object code smaller by nearly 60 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  90536	   6552	     64	  97152	  17b80	fs/btrfs/ioctl.o

After:
   text	   data	    bss	    dec	    hex	filename
  90414	   6616	     64	  97094	  17b46	fs/btrfs/ioctl.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 fs/btrfs/ioctl.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a74ed6c12d6a..feab6f61cb97 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4114,10 +4114,12 @@ static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
 	struct btrfs_ioctl_space_info *dest_orig;
 	struct btrfs_ioctl_space_info __user *user_dest;
 	struct btrfs_space_info *info;
-	u64 types[] = {BTRFS_BLOCK_GROUP_DATA,
-		       BTRFS_BLOCK_GROUP_SYSTEM,
-		       BTRFS_BLOCK_GROUP_METADATA,
-		       BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA};
+	static const u64 types[] = {
+		BTRFS_BLOCK_GROUP_DATA,
+		BTRFS_BLOCK_GROUP_SYSTEM,
+		BTRFS_BLOCK_GROUP_METADATA,
+		BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA
+	};
 	int num_types = 4;
 	int alloc_size;
 	int ret = 0;
-- 
2.14.1

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#1734999 — Re: [PATCH] btrfs: make array types static const, reduces object code size

On Tue, Sep 19, 2017 at 04:01:23PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Don't populate the read-only array types on the stack, instead make
> it static const.  Makes the object code smaller by nearly 60 bytes:
> 
> Before:
>    text	   data	    bss	    dec	    hex	filename
>   90536	   6552	     64	  97152	  17b80	fs/btrfs/ioctl.o
> 
> After:
>    text	   data	    bss	    dec	    hex	filename
>   90414	   6616	     64	  97094	  17b46	fs/btrfs/ioctl.o
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

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

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