[Libguestfs] [PATCH v3 RESEND] direct, fish: add blocksize as optional argument for launch command

[Tuan Hoang]

Allow `launch` call to accept an optional argument, called `blocksize`.

Example:

$ guestfish --listen -a raw.img
$ guestfish --remote -- launch blocksize:4096

The actual qemu command is:
[...]
    -device virtio-scsi-ccw,id=scsi
    -drive file=raw.img,cache=writeback,id=hd0,if=none
    -device scsi-hd,drive=hd0,physical_block_size=4096,logical_block_size=4096
[...]

Signed-off-by: Tuan Hoang <tmhoang at linux.ibm.com>
---
 generator/actions_core.ml | 18 ++++++++++++++++--
 lib/guestfs-internal.h    |  3 +++
 lib/launch-direct.c       |  6 ++++++
 lib/launch.c              | 12 +++++++++++-
 4 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/generator/actions_core.ml b/generator/actions_core.ml
index 7b6568b..0026650 100644
--- a/generator/actions_core.ml
+++ b/generator/actions_core.ml
@@ -26,7 +26,7 @@ open Types
 let non_daemon_functions = [
   { defaults with
     name = "launch"; added = (0, 0, 3);
-    style = RErr, [], [];
+    style = RErr, [], [OInt "blocksize"];
     fish_alias = ["run"]; progress = true; config_only = true;
     shortdesc = "launch the backend";
     longdesc = "\
@@ -36,7 +36,21 @@ You should call this after configuring the handle
 Do not call C<guestfs_launch> twice on the same handle.  Although
 it will not give an error (for historical reasons), the precise
 behaviour when you do this is not well defined.  Handles are
-very cheap to create, so create a new one for each launch." };
+very cheap to create, so create a new one for each launch.
+
+The optional arguments are:
+
+=over 4
+
+=item C<blocksize>
+
+If provided, the call will add C<physical_block_size=\"blocksize\"> and
+C<logical_block_size=\"blocksize\"> to qemu's C<-device> directive. The blocksize
+must be a power of 2 between 512 and 32768, or else it will be ignored.
+
+The default is none, and qemu would assume a blocksize of 512.
+
+=back" };
 
   { defaults with
     name = "add_drive_ro"; added = (1, 0, 38);
diff --git a/lib/guestfs-internal.h b/lib/guestfs-internal.h
index 75b8a5c..090ba58 100644
--- a/lib/guestfs-internal.h
+++ b/lib/guestfs-internal.h
@@ -513,6 +513,9 @@ struct guestfs_h {
 
   /* Used by lib/info.c.  -1 = not tested or error; else 0 or 1. */
   int qemu_img_supports_U_option;
+
+  /* Used by guestfish's launch call */
+  int blocksize;
 };
 
 /**
diff --git a/lib/launch-direct.c b/lib/launch-direct.c
index ee2dcb8..54cd8c6 100644
--- a/lib/launch-direct.c
+++ b/lib/launch-direct.c
@@ -315,6 +315,12 @@ add_drive (guestfs_h *g, struct backend_direct_data *data,
     start_list ("-device") {
       append_list ("scsi-hd");
       append_list_format ("drive=hd%zu", i);
+      if (g->blocksize >= 512 && g->blocksize <= 32768
+          && (g->blocksize & (g->blocksize-1)) == 0)
+      {
+        append_list_format ("physical_block_size=%d", g->blocksize);
+        append_list_format ("logical_block_size=%d", g->blocksize);
+      }
       if (drv->disk_label)
         append_list_format ("serial=%s", drv->disk_label);
     } end_list ();
diff --git a/lib/launch.c b/lib/launch.c
index eb7f85c..f56e389 100644
--- a/lib/launch.c
+++ b/lib/launch.c
@@ -54,7 +54,7 @@ static struct backend {
 } *backends = NULL;
 
 int
-guestfs_impl_launch (guestfs_h *g)
+guestfs_impl_launch (guestfs_h *g, const struct guestfs_launch_argv *optargs)
 {
   int r;
 
@@ -85,6 +85,16 @@ guestfs_impl_launch (guestfs_h *g)
   if (guestfs_int_lazy_make_tmpdir (g) == -1)
     return -1;
 
+  /* Add the blocksize. */
+  if (optargs->blocksize >= 512 && optargs->blocksize <= 32768
+      && (optargs->blocksize & (optargs->blocksize-1)) == 0) {
+    g->blocksize = optargs->blocksize;
+    debug (g, "using blocksize of %d", g->blocksize);
+  }
+  else {
+    debug (g, _("blocksize must be a power of 2 between 512 and 32768"));
+  }
+
   /* Some common debugging information. */
   if (g->verbose) {
     CLEANUP_FREE_VERSION struct guestfs_version *v =
-- 
2.21.0