<div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Fri, Aug 3, 2018 at 10:28 PM Nir Soffer <<a href="mailto:nirsof@gmail.com">nirsof@gmail.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This is the third version to support efficient zero for block devices on older kernels (e.g. RHEL 7.5), and file systems that do not support yet FALLOC_FS_ZERO_RANGE (e.g. NFS 4.2). Changes since v2: - Revert file_can_trim change, since it is too late to change the value after negotiation. Changing the capability dinamically may be useful internally, but it should be done via other means. - Do not depend on FALLOC_FL_* when including <linux/fs.h>. - Add common/includes/isaligned.h for is_aligned helper, implemented in a more efficient way with bitwise math. - If getting sector size fail, fall back to safe guess instead of hard failure. - More efficient alignment check using bitwise math. - For BLKZEROOUT, treat ENOTTY as EOPNOTSUPP. Theoretically possible with a mix of new headers and old or strangely configured kernel. - Use default multi line comment style. - Fix few typos in comments and commit message Issues to explore later: - Eric suggested to use the new FALLOC_FL_NO_HIDE_STALE. Requires benchmarking with a system supporting this flag. - Eric suggested to use tri-state for can_* flags. I don't see a need at this point. - Eric suggested to add can_zero. I'm not sure about the semantics of this, and it has the same issue of can_trim, reporting dynamic value. v2 was here: <a href="https://www.redhat.com/archives/libguestfs/2018-August/msg00025.html" rel="noreferrer" target="_blank">https://www.redhat.com/archives/libguestfs/2018-August/msg00025.html</a> Changes since v1: - Split to smaller patches - Skip linux only includes on other systems - Skip code using BLKZEROOUT if the macro is not defined - Try BLKZEROOUT only if the offset and count are aligned to device sector size. - initialize h->can_* properly. Before they were uninitialized if FALLOC_FL_* macros were not defined. - Use new h->can_punch_hole in file_can_trim, so now we report the actual capability once we detected it. - Use h->can_punch_hole in file_trim, so we try only once if the operation is not supported. v1 was here: <a href="https://www.redhat.com/archives/libguestfs/2018-July/msg00084.html" rel="noreferrer" target="_blank">https://www.redhat.com/archives/libguestfs/2018-July/msg00084.html</a> Nir Soffer (4): file: Avoid unsupported fallocate() calls file: Support zero without ZERO_RANGE common: Add isaligned helper module file: Zero for block devices on old kernels common/include/isaligned.h | 50 ++++++++++ plugins/file/Makefile.am | 3 +- plugins/file/file.c | 182 +++++++++++++++++++++++++++++-------- 3 files changed, 196 insertions(+), 39 deletions(-) create mode 100644 common/include/isaligned.h -- 2.17.1 </blockquote><div> </div><div>Ping? </div></div></div>