[PATCH] blockdev: add 'media=cdrom' argument to support usb cdrom emulated as cdrom

[luzhipeng]

From: zhipeng Lu <luzhipeng@cestc.cn>

The drive interface supports media=cdrom so that the usb cdrom
can be emulated as cdrom in qemu, but libvirt deprived the drive
interface, so media=cdrom is added to the blockdev interface to
support usb cdrom emulated as cdrom

Signed-off-by: zhipeng Lu <luzhipeng@cestc.cn>
---
 block.c                                     | 11 ++++++++++-
 block/block-backend.c                       | 18 ++++++++++++++++++
 hw/core/qdev-properties-system.c            |  3 +++
 hw/scsi/scsi-bus.c                          |  4 +++-
 include/block/block_int-common.h            |  1 +
 include/sysemu/block-backend-global-state.h |  2 ++
 6 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index a18f052374..d194e3039e 100644
--- a/block.c
+++ b/block.c
@@ -3787,6 +3787,7 @@ static BlockDriverState *bdrv_open_inherit(const char 
*filename,
     Error *local_err = NULL;
     QDict *snapshot_options = NULL;
     int snapshot_flags = 0;
+    int media = 0;
 
     assert(!child_class || !flags);
     assert(!child_class == !parent);
@@ -3906,6 +3907,12 @@ static BlockDriverState *bdrv_open_inherit(const char 
*filename,
         qdict_del(bs->options, "backing");
         qdict_del(options, "backing");
     }
+    if (!g_strcmp0(qdict_get_try_str(options, "media"), "cdrom")) {
+        media = 1;
+        qdict_del(bs->explicit_options, "media");
+        qdict_del(bs->options, "media");
+        qdict_del(options, "media");
+    }
 
     /* Open image file without format layer. This BlockBackend is only used for
      * probing, the block drivers will do their own bdrv_open_child() for the
@@ -4033,7 +4040,9 @@ static BlockDriverState *bdrv_open_inherit(const char 
*filename,
         bdrv_unref(bs);
         bs = snapshot_bs;
     }
-
+    if (bs && media) {
+        bs->media_cd = true;
+    }
     return bs;
 
 fail:
diff --git a/block/block-backend.c b/block/block-backend.c
index d98a96ff37..1760079a67 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -72,6 +72,7 @@ struct BlockBackend {
     uint64_t perm;
     uint64_t shared_perm;
     bool disable_perm;
+    bool media_cd;
 
     bool allow_aio_context_change;
     bool allow_write_beyond_eof;
@@ -2634,3 +2635,20 @@ int blk_make_empty(BlockBackend *blk, Error **errp)
 
     return bdrv_make_empty(blk->root, errp);
 }
+
+bool blk_is_cdrom(BlockBackend *blk)
+{
+    if (!blk) {
+        return false;
+    }
+    return blk->media_cd;
+
+}
+
+void blk_set_cdrom(BlockBackend *blk)
+{
+    if (!blk) {
+        return ;
+    }
+    blk->media_cd = true;
+}
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index a91f60567a..99df29ccb8 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -149,6 +149,9 @@ static void set_drive_helper(Object *obj, Visitor *v, const 
char *name,
             if (ret < 0) {
                 goto fail;
             }
+            if (bs->media_cd) {
+                blk_set_cdrom(blk);
+            }
         }
     }
     if (!blk) {
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index ceceafb2cd..bc2bbdc823 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -321,7 +321,9 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, 
BlockBackend *blk,
         driver = "scsi-generic";
     } else {
         dinfo = blk_legacy_dinfo(blk);
-        if (dinfo && dinfo->media_cd) {
+        if ((dinfo && dinfo->media_cd)) {
+            driver = "scsi-cd";
+        } else if (blk_is_cdrom(blk)) {
             driver = "scsi-cd";
         } else {
             driver = "scsi-hd";
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 31ae91e56e..04a814ab1b 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -1023,6 +1023,7 @@ struct BlockDriverState {
     bool probed;    /* if true, format was probed rather than specified */
     bool force_share; /* if true, always allow all shared permissions */
     bool implicit;  /* if true, this filter node was automatically inserted */
+    bool media_cd;
 
     BlockDriver *drv; /* NULL means no media */
     void *opaque;
diff --git a/include/sysemu/block-backend-global-state.h 
b/include/sysemu/block-backend-global-state.h
index 6858e39cb6..108dfad283 100644
--- a/include/sysemu/block-backend-global-state.h
+++ b/include/sysemu/block-backend-global-state.h
@@ -71,6 +71,8 @@ void blk_set_on_error(BlockBackend *blk, BlockdevOnError 
on_read_error,
                       BlockdevOnError on_write_error);
 bool blk_supports_write_perm(BlockBackend *blk);
 bool blk_is_sg(BlockBackend *blk);
+bool blk_is_cdrom(BlockBackend *blk);
+void blk_set_cdrom(BlockBackend *blk);
 void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
 int blk_get_flags(BlockBackend *blk);
 bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp);
-- 
2.31.1