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iohelper: simplify last direct write alignment

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Make alignment of last direct write more straightforward. Using
additionally two flags 'end' and 'shortRead' looks complicated.
This commit is contained in:
Nikolay Shirokovskiy 2017-09-07 10:44:14 +03:00 committed by Michal Privoznik
parent 3b8a0f6ac2
commit f830e371ef
1 changed files with 17 additions and 16 deletions
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33
src/util/iohelper.c
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@ -55,7 +55,6 @@ runIO(const char *path, int fd, int oflags)
const char *fdinname, *fdoutname;
unsigned long long total = 0;
bool direct = O_DIRECT && ((oflags & O_DIRECT) != 0);
bool shortRead = false; /* true if we hit a short read */
off_t end = 0;
#if HAVE_POSIX_MEMALIGN
@ -115,30 +114,32 @@ runIO(const char *path, int fd, int oflags)
goto cleanup;
}
if (got == 0)
break; /* End of file before end of requested data */
if (got < buflen) {
/* O_DIRECT can handle at most one short read, at end of file */
if (direct && shortRead) {
virReportSystemError(EINVAL, "%s",
_("Too many short reads for O_DIRECT"));
}
shortRead = true;
}
break;
total += got;
if (fdout == fd && direct && shortRead) {
end = total;
/* handle last write size align in direct case */
if (got < buflen && direct && fdout == fd) {
memset(buf + got, 0, buflen - got);
got = (got + alignMask) & ~alignMask;
if (safewrite(fdout, buf, got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), fdoutname);
goto cleanup;
}
if (ftruncate(fd, total) < 0) {
virReportSystemError(errno, _("Unable to truncate %s"), fdoutname);
goto cleanup;
}
break;
}
if (safewrite(fdout, buf, got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), fdoutname);
goto cleanup;
}
if (end && ftruncate(fd, end) < 0) {
virReportSystemError(errno, _("Unable to truncate %s"), fdoutname);
goto cleanup;
}
}
/* Ensure all data is written */