One of the consumers of a page aligned buffer would be posix's readv fop on O_DIRECT fds. Today the way it works is by getting a page-aligned buffer through calloc, pread()ing into this buffer and then copying its contents into a newly created iobuf's ptr. This results in an extra memcpy() which can be avoided if we could implement an api that would return an iobuf whose ptr is page-aligned. That way the iobuf->ptr can be directly passed to sys_pread() as a parameter by posix translator. Change-Id: I385139bc6ee309fc501034b3af8f7814fab8cd65 BUG: 1343838 Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com> Reviewed-on: http://review.gluster.org/14672 CentOS-regression: Gluster Build System <jenkins@build.gluster.org> Smoke: Gluster Build System <jenkins@build.gluster.org> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org> Reviewed-by: Zhou Zhengping <johnzzpcrystal@gmail.com> Reviewed-by: Jeff Darcy <jdarcy@redhat.com>