Tools: hv: Reopen the devices if read() or write() returns errors

[linux-2.6-microblaze.git] / tools / hv / hv_vss_daemon.c

diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index 92902a8..dd11187 100644 (file)
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -28,6 +28,8 @@
 #include <stdbool.h>
 #include <dirent.h>
 
+static bool fs_frozen;
+
 /* Don't use syslog() in the function since that can cause write to disk */
 static int vss_do_freeze(char *dir, unsigned int cmd)
 {
@@ -155,18 +157,27 @@ static int vss_operate(int operation)
                        continue;
                }
                error |= vss_do_freeze(ent->mnt_dir, cmd);
-               if (error && operation == VSS_OP_FREEZE)
-                       goto err;
+               if (operation == VSS_OP_FREEZE) {
+                       if (error)
+                               goto err;
+                       fs_frozen = true;
+               }
        }
 
        endmntent(mounts);
 
        if (root_seen) {
                error |= vss_do_freeze("/", cmd);
-               if (error && operation == VSS_OP_FREEZE)
-                       goto err;
+               if (operation == VSS_OP_FREEZE) {
+                       if (error)
+                               goto err;
+                       fs_frozen = true;
+               }
        }
 
+       if (operation == VSS_OP_THAW && !error)
+               fs_frozen = false;
+
        goto out;
 err:
        save_errno = errno;
@@ -175,6 +186,7 @@ err:
                endmntent(mounts);
        }
        vss_operate(VSS_OP_THAW);
+       fs_frozen = false;
        /* Call syslog after we thaw all filesystems */
        if (ent)
                syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
@@ -196,13 +208,13 @@ void print_usage(char *argv[])
 
 int main(int argc, char *argv[])
 {
-       int vss_fd, len;
+       int vss_fd = -1, len;
        int error;
        struct pollfd pfd;
        int     op;
        struct hv_vss_msg vss_msg[1];
        int daemonize = 1, long_index = 0, opt;
-       int in_handshake = 1;
+       int in_handshake;
        __u32 kernel_modver;
 
        static struct option long_options[] = {
@@ -232,6 +244,18 @@ int main(int argc, char *argv[])
        openlog("Hyper-V VSS", 0, LOG_USER);
        syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
 
+reopen_vss_fd:
+       if (vss_fd != -1)
+               close(vss_fd);
+       if (fs_frozen) {
+               if (vss_operate(VSS_OP_THAW) || fs_frozen) {
+                       syslog(LOG_ERR, "failed to thaw file system: err=%d",
+                              errno);
+                       exit(EXIT_FAILURE);
+               }
+       }
+
+       in_handshake = 1;
        vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
        if (vss_fd < 0) {
                syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
@@ -284,8 +308,7 @@ int main(int argc, char *argv[])
                if (len != sizeof(struct hv_vss_msg)) {
                        syslog(LOG_ERR, "read failed; error:%d %s",
                               errno, strerror(errno));
-                       close(vss_fd);
-                       return EXIT_FAILURE;
+                       goto reopen_vss_fd;
                }
 
                op = vss_msg->vss_hdr.operation;
@@ -312,14 +335,18 @@ int main(int argc, char *argv[])
                default:
                        syslog(LOG_ERR, "Illegal op:%d\n", op);
                }
+
+               /*
+                * The write() may return an error due to the faked VSS_OP_THAW
+                * message upon hibernation. Ignore the error by resetting the
+                * dev file, i.e. closing and re-opening it.
+                */
                vss_msg->error = error;
                len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
                if (len != sizeof(struct hv_vss_msg)) {
                        syslog(LOG_ERR, "write failed; error: %d %s", errno,
                               strerror(errno));
-
-                       if (op == VSS_OP_FREEZE)
-                               vss_operate(VSS_OP_THAW);
+                       goto reopen_vss_fd;
                }
        }