VFS accounting: small speed optimization

* Some operations may end up using the accounting macro with an
  effective zero bytes space usage difference

* Avoid calling the whole mess and its associated mount-point spinlock
  in that case.

diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index dadd883..e3c3b1c 100644 (file)
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -622,7 +622,7 @@ struct vfsops {
 #define VFS_EXTATTRCTL(MP, C, FVP, NS, N, CRED)        \
        vfs_extattrctl(MP, C, FVP, NS, N, CRED)
 #define VFS_ACCOUNT(MP, U, G, D) \
-       if (MP->mnt_op->vfs_account != NULL) \
+       if ((MP->mnt_op->vfs_account != NULL) && (D != 0)) \
                MP->mnt_op->vfs_account(MP, U, G, D);
 #define VFS_NCPGEN_SET(MP, NCP) \
        MP->mnt_op->vfs_ncpgen_set(MP, NCP)