vmspawn: initialize block device "serials" from backing file name

If we pass multiple block devices into a VM it's really useful to pass
recognizable serial numbers on them, so that we know which one is which.
qemu allows setting them, hence initialize them automatically from the
filename of the backing file, as a convenience feature.

Inside of a VM this means /dev/disk/by-id/… symlinks will be generated
with useful identifiers.

diff --git a/src/vmspawn/vmspawn.c b/src/vmspawn/vmspawn.c
index 544710d31078aa4eeb4dcd8d28e3b99fd6b248f5..8d3d168afe7c4b3e254c2acb2168cebddb85ca63 100644 (file)
--- a/src/vmspawn/vmspawn.c
+++ b/src/vmspawn/vmspawn.c
@@ -2094,24 +2094,30 @@ static int run_virtual_machine(int kvm_device_fd, int vhost_device_fd) {
         }
 
         if (arg_image) {
-                _cleanup_free_ char *escaped_image = NULL;
-
                 assert(!arg_directory);
 
-                r = strv_extend(&cmdline, "-drive");
-                if (r < 0)
+                if (strv_extend(&cmdline, "-drive") < 0)
                         return log_oom();
 
-                escaped_image = escape_qemu_value(arg_image);
+                _cleanup_free_ char *escaped_image = escape_qemu_value(arg_image);
                 if (!escaped_image)
                         return log_oom();
 
-                r = strv_extendf(&cmdline, "if=none,id=vmspawn,file=%s,format=raw,discard=%s", escaped_image, on_off(arg_discard_disk));
-                if (r < 0)
+                if (strv_extendf(&cmdline, "if=none,id=vmspawn,file=%s,format=raw,discard=%s", escaped_image, on_off(arg_discard_disk)) < 0)
                         return log_oom();
 
-                r = strv_extend_many(&cmdline, "-device", "virtio-blk-pci,drive=vmspawn,bootindex=1");
-                if (r < 0)
+                _cleanup_free_ char *image_fn = NULL;
+                if (path_extract_filename(arg_image, &image_fn) < 0)
+                        return log_error_errno(r, "Failed to extract filename from path '%s': %m", image_fn);
+
+                _cleanup_free_ char *escaped_image_fn = escape_qemu_value(image_fn);
+                if (!escaped_image_fn)
+                        return log_oom();
+
+                if (strv_extend(&cmdline, "-device") < 0)
+                        return log_oom();
+
+                if (strv_extendf(&cmdline, "virtio-blk-pci,drive=vmspawn,bootindex=1,serial=%s", escaped_image_fn) < 0)
                         return log_oom();
 
                 r = grow_image(arg_image, arg_grow_image);
@@ -2186,21 +2192,18 @@ static int run_virtual_machine(int kvm_device_fd, int vhost_device_fd) {
 
         size_t i = 0;
         STRV_FOREACH(drive, arg_extra_drives) {
-                _cleanup_free_ char *escaped_drive = NULL;
-                const char *driver = NULL;
-                struct stat st;
-
-                r = strv_extend(&cmdline, "-blockdev");
-                if (r < 0)
+                if (strv_extend(&cmdline, "-blockdev") < 0)
                         return log_oom();
 
-                escaped_drive = escape_qemu_value(*drive);
+                _cleanup_free_ char *escaped_drive = escape_qemu_value(*drive);
                 if (!escaped_drive)
                         return log_oom();
 
+                struct stat st;
                 if (stat(*drive, &st) < 0)
                         return log_error_errno(errno, "Failed to stat '%s': %m", *drive);
 
+                const char *driver = NULL;
                 if (S_ISREG(st.st_mode))
                         driver = "file";
                 else if (S_ISBLK(st.st_mode))
@@ -2208,16 +2211,22 @@ static int run_virtual_machine(int kvm_device_fd, int vhost_device_fd) {
                 else
                         return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Expected regular file or block device, not '%s'.", *drive);
 
-                r = strv_extendf(&cmdline, "driver=raw,cache.direct=off,cache.no-flush=on,file.driver=%s,file.filename=%s,node-name=vmspawn_extra_%zu", driver, escaped_drive, i);
-                if (r < 0)
+                if (strv_extendf(&cmdline, "driver=raw,cache.direct=off,cache.no-flush=on,file.driver=%s,file.filename=%s,node-name=vmspawn_extra_%zu", driver, escaped_drive, i) < 0)
                         return log_oom();
 
-                r = strv_extend(&cmdline, "-device");
+                _cleanup_free_ char *drive_fn = NULL;
+                r = path_extract_filename(*drive, &drive_fn);
                 if (r < 0)
+                        return log_error_errno(r, "Failed to extract filename from path '%s': %m", *drive);
+
+                _cleanup_free_ char *escaped_drive_fn = escape_qemu_value(drive_fn);
+                if (!escaped_drive_fn)
                         return log_oom();
 
-                r = strv_extendf(&cmdline, "scsi-hd,drive=vmspawn_extra_%zu", i++);
-                if (r < 0)
+                if (strv_extend(&cmdline, "-device") < 0)
+                        return log_oom();
+
+                if (strv_extendf(&cmdline, "scsi-hd,drive=vmspawn_extra_%zu,serial=%s", i++, escaped_drive_fn) < 0)
                         return log_oom();
         }