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iohelper: introduce new struct to carry copy operation parameters

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this is in preparation for a minor refactoring of the copy
function itself out of runIO().

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Claudio Fontana 2022-05-06 15:10:45 +02:00 committed by Daniel P. Berrangé
parent 0495f841ee
commit 8188716522
1 changed files with 53 additions and 42 deletions
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95
src/util/iohelper.c
View File

@ -45,6 +45,16 @@
# define O_DIRECT 0
#endif
struct runIOParams {
bool isBlockDev;
bool isDirect;
bool isWrite;
int fdin;
const char *fdinname;
int fdout;
const char *fdoutname;
};
static int
runIO(const char *path, int fd, int oflags)
{
@ -53,13 +63,9 @@ runIO(const char *path, int fd, int oflags)
size_t buflen = 1024*1024;
intptr_t alignMask = 64*1024 - 1;
int ret = -1;
int fdin, fdout;
const char *fdinname, *fdoutname;
unsigned long long total = 0;
bool direct = O_DIRECT && ((oflags & O_DIRECT) != 0);
off_t end = 0;
off_t total = 0;
struct stat sb;
bool isBlockDev = false;
struct runIOParams p;
#if WITH_POSIX_MEMALIGN
if (posix_memalign(&base, alignMask + 1, buflen))
@ -77,34 +83,23 @@ runIO(const char *path, int fd, int oflags)
fd, path);
goto cleanup;
}
isBlockDev = S_ISBLK(sb.st_mode);
p.isBlockDev = S_ISBLK(sb.st_mode);
p.isDirect = O_DIRECT && (oflags & O_DIRECT);
switch (oflags & O_ACCMODE) {
case O_RDONLY:
fdin = fd;
fdinname = path;
fdout = STDOUT_FILENO;
fdoutname = "stdout";
/* To make the implementation simpler, we give up on any
* attempt to use O_DIRECT in a non-trivial manner. */
if (!isBlockDev && direct && ((end = lseek(fd, 0, SEEK_CUR)) != 0)) {
virReportSystemError(end < 0 ? errno : EINVAL, "%s",
_("O_DIRECT read needs entire seekable file"));
goto cleanup;
}
p.isWrite = false;
p.fdin = fd;
p.fdinname = path;
p.fdout = STDOUT_FILENO;
p.fdoutname = "stdout";
break;
case O_WRONLY:
fdin = STDIN_FILENO;
fdinname = "stdin";
fdout = fd;
fdoutname = path;
/* To make the implementation simpler, we give up on any
* attempt to use O_DIRECT in a non-trivial manner. */
if (!isBlockDev && direct && (end = lseek(fd, 0, SEEK_END)) != 0) {
virReportSystemError(end < 0 ? errno : EINVAL, "%s",
_("O_DIRECT write needs empty seekable file"));
goto cleanup;
}
p.isWrite = true;
p.fdin = STDIN_FILENO;
p.fdinname = "stdin";
p.fdout = fd;
p.fdoutname = path;
break;
case O_RDWR:
@ -114,6 +109,22 @@ runIO(const char *path, int fd, int oflags)
(oflags & O_ACCMODE));
goto cleanup;
}
/* To make the implementation simpler, we give up on any
* attempt to use O_DIRECT in a non-trivial manner. */
if (!p.isBlockDev && p.isDirect) {
off_t off;
if (p.isWrite) {
if ((off = lseek(fd, 0, SEEK_END)) != 0) {
virReportSystemError(off < 0 ? errno : EINVAL, "%s",
_("O_DIRECT write needs empty seekable file"));
goto cleanup;
}
} else if ((off = lseek(fd, 0, SEEK_CUR)) != 0) {
virReportSystemError(off < 0 ? errno : EINVAL, "%s",
_("O_DIRECT read needs entire seekable file"));
goto cleanup;
}
}
while (1) {
ssize_t got;
@ -124,16 +135,16 @@ runIO(const char *path, int fd, int oflags)
* writes will be aligned.
* In other cases using saferead reduces number of syscalls.
*/
if (fdin == fd && direct) {
if ((got = read(fdin, buf, buflen)) < 0 &&
if (!p.isWrite && p.isDirect) {
if ((got = read(p.fdin, buf, buflen)) < 0 &&
errno == EINTR)
continue;
} else {
got = saferead(fdin, buf, buflen);
got = saferead(p.fdin, buf, buflen);
}
if (got < 0) {
virReportSystemError(errno, _("Unable to read %s"), fdinname);
virReportSystemError(errno, _("Unable to read %s"), p.fdinname);
goto cleanup;
}
if (got == 0)
@ -142,35 +153,35 @@ runIO(const char *path, int fd, int oflags)
total += got;
/* handle last write size align in direct case */
if (got < buflen && direct && fdout == fd) {
if (got < buflen && p.isDirect && p.isWrite) {
ssize_t aligned_got = (got + alignMask) & ~alignMask;
memset(buf + got, 0, aligned_got - got);
if (safewrite(fdout, buf, aligned_got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), fdoutname);
if (safewrite(p.fdout, buf, aligned_got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), p.fdoutname);
goto cleanup;
}
if (!isBlockDev && ftruncate(fd, total) < 0) {
virReportSystemError(errno, _("Unable to truncate %s"), fdoutname);
if (!p.isBlockDev && ftruncate(p.fdout, total) < 0) {
virReportSystemError(errno, _("Unable to truncate %s"), p.fdoutname);
goto cleanup;
}
break;
}
if (safewrite(fdout, buf, got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), fdoutname);
if (safewrite(p.fdout, buf, got) < 0) {
virReportSystemError(errno, _("Unable to write %s"), p.fdoutname);
goto cleanup;
}
}
/* Ensure all data is written */
if (virFileDataSync(fdout) < 0) {
if (virFileDataSync(p.fdout) < 0) {
if (errno != EINVAL && errno != EROFS) {
/* fdatasync() may fail on some special FDs, e.g. pipes */
virReportSystemError(errno, _("unable to fsync %s"), fdoutname);
virReportSystemError(errno, _("unable to fsync %s"), p.fdoutname);
goto cleanup;
}
}