[libvirt] [PATCH 3/4] iohelper: reduce zero-out in align case
We only need to zero-out bytes that will be written.
May be we even don't need to zero-out at all because
of immediate truncate.
---
src/util/iohelper.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/src/util/iohelper.c b/src/util/iohelper.c
index 1896fd3..fe15a92 100644
--- a/src/util/iohelper.c
+++ b/src/util/iohelper.c
@@ -120,10 +120,11 @@ runIO(const char *path, int fd, int oflags)
/* handle last write size align in direct case */
if (got < buflen && direct && fdout == fd) {
- memset(buf + got, 0, buflen - got);
- got = (got + alignMask) & ~alignMask;
+ ssize_t aligned_got = (got + alignMask) & ~alignMask;
- if (safewrite(fdout, buf, got) < 0) {
+ memset(buf + got, 0, aligned_got - got);
+
+ if (safewrite(fdout, buf, aligned_got) < 0) {
virReportSystemError(errno, _("Unable to write %s"),
fdoutname);
goto cleanup;
}
--
1.8.3.1