1 files changed, 82 insertions, 13 deletions

diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index 6a213b8..5e63f70 100644
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -36,6 +36,7 @@
 #include <linux/hyperv.h>
 #include <linux/netlink.h>
 #include <syslog.h>
+#include <getopt.h>
 
 static struct sockaddr_nl addr;
 
@@ -44,35 +45,51 @@ static struct sockaddr_nl addr;
 #endif
 
 
-static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op)
+/* Don't use syslog() in the function since that can cause write to disk */
+static int vss_do_freeze(char *dir, unsigned int cmd)
 {
 	int ret, fd = open(dir, O_RDONLY);
 
 	if (fd < 0)
 		return 1;
+
 	ret = ioctl(fd, cmd, 0);
-	syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno));
+
+	/*
+	 * If a partition is mounted more than once, only the first
+	 * FREEZE/THAW can succeed and the later ones will get
+	 * EBUSY/EINVAL respectively: there could be 2 cases:
+	 * 1) a user may mount the same partition to differnt directories
+	 *  by mistake or on purpose;
+	 * 2) The subvolume of btrfs appears to have the same partition
+	 * mounted more than once.
+	 */
+	if (ret) {
+		if ((cmd == FIFREEZE && errno == EBUSY) ||
+		    (cmd == FITHAW && errno == EINVAL)) {
+			close(fd);
+			return 0;
+		}
+	}
+
 	close(fd);
 	return !!ret;
 }
 
 static int vss_operate(int operation)
 {
-	char *fs_op;
 	char match[] = "/dev/";
 	FILE *mounts;
 	struct mntent *ent;
 	unsigned int cmd;
-	int error = 0, root_seen = 0;
+	int error = 0, root_seen = 0, save_errno = 0;
 
 	switch (operation) {
 	case VSS_OP_FREEZE:
 		cmd = FIFREEZE;
-		fs_op = "freeze";
 		break;
 	case VSS_OP_THAW:
 		cmd = FITHAW;
-		fs_op = "thaw";
 		break;
 	default:
 		return -1;
@@ -85,7 +102,7 @@ static int vss_operate(int operation)
 	while ((ent = getmntent(mounts))) {
 		if (strncmp(ent->mnt_fsname, match, strlen(match)))
 			continue;
-		if (strcmp(ent->mnt_type, "iso9660") == 0)
+		if (hasmntopt(ent, MNTOPT_RO) != NULL)
 			continue;
 		if (strcmp(ent->mnt_type, "vfat") == 0)
 			continue;
@@ -93,14 +110,30 @@ static int vss_operate(int operation)
 			root_seen = 1;
 			continue;
 		}
-		error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op);
+		error |= vss_do_freeze(ent->mnt_dir, cmd);
+		if (error && operation == VSS_OP_FREEZE)
+			goto err;
 	}
-	endmntent(mounts);
 
 	if (root_seen) {
-		error |= vss_do_freeze("/", cmd, fs_op);
+		error |= vss_do_freeze("/", cmd);
+		if (error && operation == VSS_OP_FREEZE)
+			goto err;
 	}
 
+	goto out;
+err:
+	save_errno = errno;
+	vss_operate(VSS_OP_THAW);
+	/* Call syslog after we thaw all filesystems */
+	if (ent)
+		syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
+		       ent->mnt_dir, save_errno, strerror(save_errno));
+	else
+		syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
+		       strerror(save_errno));
+out:
+	endmntent(mounts);
 	return error;
 }
 
@@ -131,7 +164,15 @@ static int netlink_send(int fd, struct cn_msg *msg)
 	return sendmsg(fd, &message, 0);
 }
 
-int main(void)
+void print_usage(char *argv[])
+{
+	fprintf(stderr, "Usage: %s [options]\n"
+		"Options are:\n"
+		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
+		"  -h, --help             print this help\n", argv[0]);
+}
+
+int main(int argc, char *argv[])
 {
 	int fd, len, nl_group;
 	int error;
@@ -143,8 +184,28 @@ int main(void)
 	struct hv_vss_msg *vss_msg;
 	char *vss_recv_buffer;
 	size_t vss_recv_buffer_len;
+	int daemonize = 1, long_index = 0, opt;
+
+	static struct option long_options[] = {
+		{"help",	no_argument,	   0,  'h' },
+		{"no-daemon",	no_argument,	   0,  'n' },
+		{0,		0,		   0,  0   }
+	};
+
+	while ((opt = getopt_long(argc, argv, "hn", long_options,
+				  &long_index)) != -1) {
+		switch (opt) {
+		case 'n':
+			daemonize = 0;
+			break;
+		case 'h':
+		default:
+			print_usage(argv);
+			exit(EXIT_FAILURE);
+		}
+	}
 
-	if (daemon(1, 0))
+	if (daemonize && daemon(1, 0))
 		return 1;
 
 	openlog("Hyper-V VSS", 0, LOG_USER);
@@ -249,8 +310,16 @@ int main(void)
 		case VSS_OP_FREEZE:
 		case VSS_OP_THAW:
 			error = vss_operate(op);
-			if (error)
+			syslog(LOG_INFO, "VSS: op=%s: %s\n",
+				op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
+				error ? "failed" : "succeeded");
+
+			if (error) {
 				error = HV_E_FAIL;
+				syslog(LOG_ERR, "op=%d failed!", op);
+				syslog(LOG_ERR, "report it with these files:");
+				syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
+			}
 			break;
 		default:
 			syslog(LOG_ERR, "Illegal op:%d\n", op);