vmspawn: add --discard-disk= to control handling of disk discard requests

Fixes issue #32024, using --discard-disk=yes will enable handling of disk
discarding requests, saving space for long running VMs as desired.

diff --git a/man/systemd-vmspawn.xml b/man/systemd-vmspawn.xml
index 90ddc9b6740ba3afde539932cd1eb0bd5cf660cd..da3ac84a4027eb1a07615afd7b0866a3deeb9756 100644 (file)
--- a/man/systemd-vmspawn.xml
+++ b/man/systemd-vmspawn.xml
@@ -243,6 +243,16 @@
           <xi:include href="version-info.xml" xpointer="v256"/></listitem>
         </varlistentry>
 
+        <varlistentry>
+          <term><option>--discard-disk=<replaceable>BOOL</replaceable></option></term>
+
+          <listitem><para>Controls whether qemu processes discard requests from the VM.
+          This prevents long running VMs from using more disk space than required.
+          This is enabled by default.</para>
+
+          <xi:include href="version-info.xml" xpointer="v256"/></listitem>
+        </varlistentry>
+
         <varlistentry>
           <term><option>--secure-boot=</option><replaceable>BOOL</replaceable></term>
 

diff --git a/src/vmspawn/vmspawn.c b/src/vmspawn/vmspawn.c
index dbd15e5f29d175951a49deeac30ebb07cc4fed35..cb74b5c97ed5d217fb726456dfb35165c7a7fb52 100644 (file)
--- a/src/vmspawn/vmspawn.c
+++ b/src/vmspawn/vmspawn.c
@@ -97,6 +97,7 @@ static char **arg_extra_drives = NULL;
 static char *arg_background = NULL;
 static bool arg_pass_ssh_key = true;
 static char *arg_ssh_key_type = NULL;
+static bool arg_discard_disk = true;
 
 STATIC_DESTRUCTOR_REGISTER(arg_directory, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_image, freep);
@@ -146,6 +147,7 @@ static int help(void) {
                "     --network-user-mode   Use user mode networking\n"
                "     --secure-boot=BOOL    Enable searching for firmware supporting SecureBoot\n"
                "     --firmware=PATH|list  Select firmware definition file (or list available)\n"
+               "     --discard-disk=BOOL   Control processing of discard requests\n"
                "\n%3$sSystem Identity:%4$s\n"
                "  -M --machine=NAME        Set the machine name for the VM\n"
                "     --uuid=UUID           Set a specific machine UUID for the VM\n"
@@ -213,6 +215,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_SET_CREDENTIAL,
                 ARG_LOAD_CREDENTIAL,
                 ARG_FIRMWARE,
+                ARG_DISCARD_DISK,
                 ARG_CONSOLE,
                 ARG_BACKGROUND,
         };
@@ -254,6 +257,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "set-credential",    required_argument, NULL, ARG_SET_CREDENTIAL    },
                 { "load-credential",   required_argument, NULL, ARG_LOAD_CREDENTIAL   },
                 { "firmware",          required_argument, NULL, ARG_FIRMWARE          },
+                { "discard-disk",      required_argument, NULL, ARG_DISCARD_DISK      },
                 { "background",        required_argument, NULL, ARG_BACKGROUND        },
                 {}
         };
@@ -507,6 +511,12 @@ static int parse_argv(int argc, char *argv[]) {
 
                         break;
 
+                case ARG_DISCARD_DISK:
+                        r = parse_boolean_argument("--discard-disk=", optarg, &arg_discard_disk);
+                        if (r < 0)
+                                return r;
+                        break;
+
                 case ARG_BACKGROUND:
                         r = free_and_strdup_warn(&arg_background, optarg);
                         if (r < 0)
@@ -1533,7 +1543,7 @@ static int run_virtual_machine(int kvm_device_fd, int vhost_device_fd) {
                 if (!escaped_image)
                         log_oom();
 
-                r = strv_extendf(&cmdline, "if=none,id=mkosi,file=%s,format=raw", escaped_image);
+                r = strv_extendf(&cmdline, "if=none,id=mkosi,file=%s,format=raw,discard=%s", escaped_image, on_off(arg_discard_disk));
                 if (r < 0)
                         return log_oom();