If CONFIG_EXT2_FS_POSIX_ACL is not configured, ext2_clear_inode() will be empty
function. However, there still will be call and immediate return which can be
avoided.
Signed-off-by: Alexey Dobriyan <[email protected]>
---
fs/ext2/super.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -184,9 +184,9 @@ static void destroy_inodecache(void)
kmem_cache_destroy(ext2_inode_cachep);
}
+#ifdef CONFIG_EXT2_FS_POSIX_ACL
static void ext2_clear_inode(struct inode *inode)
{
-#ifdef CONFIG_EXT2_FS_POSIX_ACL
struct ext2_inode_info *ei = EXT2_I(inode);
if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
@@ -197,8 +197,10 @@ static void ext2_clear_inode(struct inode *inode)
posix_acl_release(ei->i_default_acl);
ei->i_default_acl = EXT2_ACL_NOT_CACHED;
}
-#endif
}
+#else
+#define ext2_clear_inode NULL
+#endif
static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
On Mon, 9 July 2007 08:11:22 +0400, Alexey Dobriyan wrote:
>
> If CONFIG_EXT2_FS_POSIX_ACL is not configured, ext2_clear_inode() will be empty
> function. However, there still will be call and immediate return which can be
> avoided.
> [...]
> +#ifdef CONFIG_EXT2_FS_POSIX_ACL
> static void ext2_clear_inode(struct inode *inode)
> {
> -#ifdef CONFIG_EXT2_FS_POSIX_ACL
> struct ext2_inode_info *ei = EXT2_I(inode);
>
> if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
> @@ -197,8 +197,10 @@ static void ext2_clear_inode(struct inode *inode)
> posix_acl_release(ei->i_default_acl);
> ei->i_default_acl = EXT2_ACL_NOT_CACHED;
> }
> -#endif
> }
> +#else
> +#define ext2_clear_inode NULL
> +#endif
Are you sure your patch makes a difference? Does the resulting binary
change at all?
Jörn
--
Fancy algorithms are slow when n is small, and n is usually small.
Fancy algorithms have big constants. Until you know that n is
frequently going to be big, don't get fancy.
-- Rob Pike
On Mon, Jul 09, 2007 at 10:34:32AM +0200, J?rn Engel wrote:
> On Mon, 9 July 2007 08:11:22 +0400, Alexey Dobriyan wrote:
> >
> > If CONFIG_EXT2_FS_POSIX_ACL is not configured, ext2_clear_inode() will be empty
> > function. However, there still will be call and immediate return which can be
> > avoided.
> > [...]
> > +#ifdef CONFIG_EXT2_FS_POSIX_ACL
> > static void ext2_clear_inode(struct inode *inode)
> > {
> > -#ifdef CONFIG_EXT2_FS_POSIX_ACL
> > struct ext2_inode_info *ei = EXT2_I(inode);
> >
> > if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
> > @@ -197,8 +197,10 @@ static void ext2_clear_inode(struct inode *inode)
> > posix_acl_release(ei->i_default_acl);
> > ei->i_default_acl = EXT2_ACL_NOT_CACHED;
> > }
> > -#endif
> > }
> > +#else
> > +#define ext2_clear_inode NULL
> > +#endif
>
> Are you sure your patch makes a difference? Does the resulting binary
> change at all?
Yes. Note that ext2_clear_inode() is referenced from ext2_sops, so even
empty, it leaves traces in resulting kernel.
On Mon, 9 July 2007 22:01:48 +0400, Alexey Dobriyan wrote:
>
> Yes. Note that ext2_clear_inode() is referenced from ext2_sops, so even
> empty, it leaves traces in resulting kernel.
Is that your opinion or have you actually measured a difference?
I strongly suspect that compilers are smart enough to optimize away a
call to an empty static function.
Jörn
--
Fancy algorithms are slow when n is small, and n is usually small.
Fancy algorithms have big constants. Until you know that n is
frequently going to be big, don't get fancy.
-- Rob Pike
On Mon, 2007-07-09 at 22:00 +0200, J?rn Engel wrote:
> On Mon, 9 July 2007 22:01:48 +0400, Alexey Dobriyan wrote:
> >
> > Yes. Note that ext2_clear_inode() is referenced from ext2_sops, so even
> > empty, it leaves traces in resulting kernel.
>
> Is that your opinion or have you actually measured a difference?
> I strongly suspect that compilers are smart enough to optimize away a
> call to an empty static function.
It's not a direct call to a static function. It is called as a
super_ops method. I don't think the overhead is very significant, but
it doesn't look like it could do any harm.
--
David Kleikamp
IBM Linux Technology Center
On Mon, 9 July 2007 17:02:20 -0500, Dave Kleikamp wrote:
>
> It's not a direct call to a static function. It is called as a
> super_ops method. I don't think the overhead is very significant, but
> it doesn't look like it could do any harm.
Ah, I missed that fact. Yep, looks fine to me.
Jörn
--
Joern's library part 7:
http://www.usenix.org/publications/library/proceedings/neworl/full_papers/mckusick.a
On Mon, 9 Jul 2007 22:00:03 +0200
J?rn Engel <[email protected]> wrote:
> On Mon, 9 July 2007 22:01:48 +0400, Alexey Dobriyan wrote:
> >
> > Yes. Note that ext2_clear_inode() is referenced from ext2_sops, so even
> > empty, it leaves traces in resulting kernel.
>
> Is that your opinion or have you actually measured a difference?
> I strongly suspect that compilers are smart enough to optimize away a
> call to an empty static function.
>
It saves a big 16 bytes of text here.