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iohelper: skip lseek() and ftruncate() on block devices

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Signed-off-by: Simon Rowe <simon.rowe@nutanix.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Simon Rowe 2021-08-23 15:40:47 +00:00 committed by Michal Privoznik
parent 7e7747cc2d
commit 5646b7c5e1
1 changed files with 15 additions and 3 deletions
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18
src/util/iohelper.c
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@ -28,6 +28,8 @@
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "virthread.h"
#include "virfile.h"
@ -56,6 +58,8 @@ runIO(const char *path, int fd, int oflags)
unsigned long long total = 0;
bool direct = O_DIRECT && ((oflags & O_DIRECT) != 0);
off_t end = 0;
struct stat sb;
bool isBlockDev = false;
#if WITH_POSIX_MEMALIGN
if (posix_memalign(&base, alignMask + 1, buflen))
@ -67,6 +71,14 @@ runIO(const char *path, int fd, int oflags)
buf = (char *) (((intptr_t) base + alignMask) & ~alignMask);
#endif
if (fstat(fd, &sb) < 0) {
virReportSystemError(errno,
_("Unable to access file descriptor %d path %s"),
fd, path);
goto cleanup;
}
isBlockDev = S_ISBLK(sb.st_mode);
switch (oflags & O_ACCMODE) {
case O_RDONLY:
fdin = fd;
@ -75,7 +87,7 @@ runIO(const char *path, int fd, int oflags)
fdoutname = "stdout";
/* To make the implementation simpler, we give up on any
* attempt to use O_DIRECT in a non-trivial manner. */
if (direct && ((end = lseek(fd, 0, SEEK_CUR)) != 0)) {
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;
@ -88,7 +100,7 @@ runIO(const char *path, int fd, int oflags)
fdoutname = path;
/* To make the implementation simpler, we give up on any
* attempt to use O_DIRECT in a non-trivial manner. */
if (direct && (end = lseek(fd, 0, SEEK_END)) != 0) {
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;
@ -140,7 +152,7 @@ runIO(const char *path, int fd, int oflags)
goto cleanup;
}
if (ftruncate(fd, total) < 0) {
if (!isBlockDev && ftruncate(fd, total) < 0) {
virReportSystemError(errno, _("Unable to truncate %s"), fdoutname);
goto cleanup;
}