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[Qemu-block] [PATCH 1/2] osdep: Add runtime OFD lock detection
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH 1/2] osdep: Add runtime OFD lock detection |
Date: |
Fri, 21 Jul 2017 18:20:58 +0800 |
Build time check of OFD lock is not sufficient and can cause image open
errors when the runtime environment doesn't support it.
Add a helper function to probe it at runtime, additionally. Also provide
a qemu_has_ofd_lock() for callers to check the status.
Signed-off-by: Fam Zheng <address@hidden>
---
include/qemu/osdep.h | 1 +
util/osdep.c | 72 +++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 64 insertions(+), 9 deletions(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 3b74f6fcb2..6855b94bbf 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -357,6 +357,7 @@ int qemu_dup(int fd);
int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
int qemu_unlock_fd(int fd, int64_t start, int64_t len);
int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
+bool qemu_has_ofd_lock(void);
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
diff --git a/util/osdep.c b/util/osdep.c
index a2863c8e53..b275c6579a 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -38,13 +38,8 @@ extern int madvise(caddr_t, size_t, int);
#include "qemu/error-report.h"
#include "monitor/monitor.h"
-#ifdef F_OFD_SETLK
-#define QEMU_SETLK F_OFD_SETLK
-#define QEMU_GETLK F_OFD_GETLK
-#else
-#define QEMU_SETLK F_SETLK
-#define QEMU_GETLK F_GETLK
-#endif
+static int fcntl_op_setlk = -1;
+static int fcntl_op_getlk = -1;
static bool fips_enabled = false;
@@ -149,6 +144,63 @@ static int qemu_parse_fdset(const char *param)
return qemu_parse_fd(param);
}
+static void qemu_probe_lock_ops(void)
+{
+ if (fcntl_op_setlk == -1) {
+#ifdef F_OFD_SETLK
+ int fd;
+ int ret;
+ const char *tmpdir;
+ char *filename;
+ struct flock fl = {
+ .l_whence = SEEK_SET,
+ .l_start = 0,
+ .l_len = 0,
+ .l_type = F_WRLCK,
+ };
+
+ tmpdir = getenv("TMPDIR");
+ if (!tmpdir) {
+ tmpdir = "/var/tmp";
+ }
+ filename = g_strdup_printf("%s/qemu_lock_probe.XXXXXX", tmpdir);
+ fd = mkstemp(filename);
+ if (fd < 0) {
+ fprintf(stderr, "Failed to create temporary file '%s': %s\n",
+ filename, strerror(errno));
+ fcntl_op_setlk = F_SETLK;
+ fcntl_op_getlk = F_GETLK;
+ goto out;
+ }
+ ret = fcntl(fd, F_OFD_SETLK, &fl);
+ close(fd);
+ unlink(filename);
+ if (!ret) {
+ fcntl_op_setlk = F_OFD_SETLK;
+ fcntl_op_getlk = F_OFD_GETLK;
+ } else {
+ fcntl_op_setlk = F_SETLK;
+ fcntl_op_getlk = F_GETLK;
+ }
+out:
+ g_free(filename);
+#else
+ fcntl_op_setlk = F_SETLK;
+ fcntl_op_getlk = F_GETLK;
+#endif
+ }
+}
+
+bool qemu_has_ofd_lock(void)
+{
+ qemu_probe_lock_ops();
+#ifdef F_OFD_SETLK
+ return fcntl_op_setlk == F_OFD_SETLK;
+#else
+ return false;
+#endif
+}
+
static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
{
int ret;
@@ -158,7 +210,8 @@ static int qemu_lock_fcntl(int fd, int64_t start, int64_t
len, int fl_type)
.l_len = len,
.l_type = fl_type,
};
- ret = fcntl(fd, QEMU_SETLK, &fl);
+ qemu_probe_lock_ops();
+ ret = fcntl(fd, fcntl_op_setlk, &fl);
return ret == -1 ? -errno : 0;
}
@@ -181,7 +234,8 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
bool exclusive)
.l_len = len,
.l_type = exclusive ? F_WRLCK : F_RDLCK,
};
- ret = fcntl(fd, QEMU_GETLK, &fl);
+ qemu_probe_lock_ops();
+ ret = fcntl(fd, fcntl_op_getlk, &fl);
if (ret == -1) {
return -errno;
} else {
--
2.13.3