lxclock and lxccontainer: switch from flock to fcntl

flock is not supported on nfs.  fcntl is at least supported on newer
(v3 and above) nfs.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Tested-by: zoolook <nbensa+lxcusers@gmail.com>

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index 2edf74918e5d80397d91c891d1f87f7c5f9fb098..cf5252b08c329a4ade7c696a68191aa5b02cb0e7 100644 (file)
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -23,6 +23,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <sched.h>
 #include "config.h"
 #include "lxc.h"
@@ -39,7 +40,6 @@
 #include <lxc/utils.h>
 #include <lxc/monitor.h>
 #include <sched.h>
-#include <fcntl.h>
 #include <arpa/inet.h>
 #include <ifaddrs.h>
 
@@ -66,6 +66,8 @@ int ongoing_create(struct lxc_container *c)
        int len = strlen(c->config_path) + strlen(c->name) + 10;
        char *path = alloca(len);
        int fd, ret;
+       struct flock lk;
+
        ret = snprintf(path, len, "%s/%s/partial", c->config_path, c->name);
        if (ret < 0 || ret >= len) {
                ERROR("Error writing partial pathname");
@@ -82,8 +84,12 @@ int ongoing_create(struct lxc_container *c)
                process_unlock();
                return 0;
        }
-       if ((ret = flock(fd, LOCK_EX | LOCK_NB)) == -1 &&
-                       errno == EWOULDBLOCK) {
+       lk.l_type = F_WRLCK;
+       lk.l_whence = SEEK_SET;
+       lk.l_start = 0;
+       lk.l_len = 0;
+       lk.l_pid = -1;
+       if (fcntl(fd, F_GETLK, &lk) == 0 && lk.l_pid != -1) {
                // create is still ongoing
                close(fd);
                process_unlock();
@@ -101,6 +107,8 @@ int create_partial(struct lxc_container *c)
        int len = strlen(c->config_path) + strlen(c->name) + 10;
        char *path = alloca(len);
        int fd, ret;
+       struct flock lk;
+
        ret = snprintf(path, len, "%s/%s/partial", c->config_path, c->name);
        if (ret < 0 || ret >= len) {
                ERROR("Error writing partial pathname");
@@ -108,12 +116,16 @@ int create_partial(struct lxc_container *c)
        }
        if (process_lock())
                return -1;
-       if ((fd=open(path, O_CREAT | O_EXCL, 0755)) < 0) {
+       if ((fd=open(path, O_RDWR | O_CREAT | O_EXCL, 0755)) < 0) {
                SYSERROR("Erorr creating partial file");
                process_unlock();
                return -1;
        }
-       if (flock(fd, LOCK_EX) < 0) {
+       lk.l_type = F_WRLCK;
+       lk.l_whence = SEEK_SET;
+       lk.l_start = 0;
+       lk.l_len = 0;
+       if (fcntl(fd, F_SETLKW, &lk) < 0) {
                SYSERROR("Error locking partial file %s", path);
                close(fd);
                process_unlock();

diff --git a/src/lxc/lxclock.c b/src/lxc/lxclock.c
index 4bbe873be8e26ba7a81e516f135893484d562bb7..d004cc55ffa303994e8bea8443497cb80feb6a07 100644 (file)
--- a/src/lxc/lxclock.c
+++ b/src/lxc/lxclock.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include <lxc/utils.h>
 #include <lxc/log.h>
 #include <lxc/lxccontainer.h>
@@ -111,6 +112,7 @@ out:
 int lxclock(struct lxc_lock *l, int timeout)
 {
        int ret = -1, saved_errno = errno;
+       struct flock lk;
 
        switch(l->type) {
        case LXC_LOCK_ANON_SEM:
@@ -152,7 +154,11 @@ int lxclock(struct lxc_lock *l, int timeout)
                                goto out;
                        }
                }
-               ret = flock(l->u.f.fd, LOCK_EX);
+               lk.l_type = F_WRLCK;
+               lk.l_whence = SEEK_SET;
+               lk.l_start = 0;
+               lk.l_len = 0;
+               ret = fcntl(l->u.f.fd, F_SETLKW, &lk);
                process_unlock();
                if (ret == -1)
                        saved_errno = errno;
@@ -167,6 +173,7 @@ out:
 int lxcunlock(struct lxc_lock *l)
 {
        int ret = 0, saved_errno = errno;
+       struct flock lk;
 
        switch(l->type) {
        case LXC_LOCK_ANON_SEM:
@@ -179,7 +186,12 @@ int lxcunlock(struct lxc_lock *l)
        case LXC_LOCK_FLOCK:
                process_lock();
                if (l->u.f.fd != -1) {
-                       if ((ret = flock(l->u.f.fd, LOCK_UN)) < 0)
+                       lk.l_type = F_UNLCK;
+                       lk.l_whence = SEEK_SET;
+                       lk.l_start = 0;
+                       lk.l_len = 0;
+                       ret = fcntl(l->u.f.fd, F_SETLK, &lk);
+                       if (ret < 0)
                                saved_errno = errno;
                        close(l->u.f.fd);
                        l->u.f.fd = -1;