vduse-blk: Add name option

Currently we use 'id' option as the name of VDUSE device.
It's a bit confusing since we use one value for two different
purposes: the ID to identfy the export within QEMU (must be
distinct from any other exports in the same QEMU process, but
can overlap with names used by other processes), and the VDUSE
name to uniquely identify it on the host (must be distinct from
other VDUSE devices on the same host, but can overlap with other
export types like NBD in the same process). To make it clear,
this patch adds a separate 'name' option to specify the VDUSE
name for the vduse-blk export instead.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220614051532.92-7-xieyongji@bytedance.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

4 files changed, 13 insertions, 11 deletions

diff --git a/block/export/vduse-blk.c b/block/export/vduse-blk.c
index 066e088b00..f101c24c3f 100644
--- a/block/export/vduse-blk.c
+++ b/block/export/vduse-blk.c
@@ -300,7 +300,7 @@ static int vduse_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
         features |= 1ULL << VIRTIO_BLK_F_RO;
     }
 
-    vblk_exp->dev = vduse_dev_create(exp->id, VIRTIO_ID_BLOCK, 0,
+    vblk_exp->dev = vduse_dev_create(vblk_opts->name, VIRTIO_ID_BLOCK, 0,
                                      features, num_queues,
                                      sizeof(struct virtio_blk_config),
                                      (char *)&config, &vduse_blk_ops,
@@ -312,7 +312,7 @@ static int vduse_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
     }
 
     vblk_exp->recon_file = g_strdup_printf("%s/vduse-blk-%s",
-                                           g_get_tmp_dir(), exp->id);
+                                           g_get_tmp_dir(), vblk_opts->name);
     if (vduse_set_reconnect_log_file(vblk_exp->dev, vblk_exp->recon_file)) {
         error_setg(errp, "failed to set reconnect log file");
         ret = -EINVAL;
diff --git a/docs/tools/qemu-storage-daemon.rst b/docs/tools/qemu-storage-daemon.rst
index 034f2809a6..ea00149a63 100644
--- a/docs/tools/qemu-storage-daemon.rst
+++ b/docs/tools/qemu-storage-daemon.rst
@@ -77,7 +77,7 @@ Standard options:
   --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=unix,addr.path=<socket-path>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
   --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=fd,addr.str=<fd>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
   --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>[,growable=on|off][,writable=on|off][,allow-other=on|off|auto]
-  --export [type=]vduse-blk,id=<id>,node-name=<node-name>[,writable=on|off][,num-queues=<num-queues>][,queue-size=<queue-size>][,logical-block-size=<block-size>][,serial=<serial-number>]
+  --export [type=]vduse-blk,id=<id>,node-name=<node-name>,name=<vduse-name>[,writable=on|off][,num-queues=<num-queues>][,queue-size=<queue-size>][,logical-block-size=<block-size>][,serial=<serial-number>]
 
   is a block export definition. ``node-name`` is the block node that should be
   exported. ``writable`` determines whether or not the export allows write
@@ -111,7 +111,8 @@ Standard options:
   ``allow-other`` to auto (the default) will try enabling this option, and on
   error fall back to disabling it.
 
-  The ``vduse-blk`` export type uses the ``id`` as the VDUSE device name.
+  The ``vduse-blk`` export type takes a ``name`` (must be unique across the host)
+  to create the VDUSE device.
   ``num-queues`` sets the number of virtqueues (the default is 1).
   ``queue-size`` sets the virtqueue descriptor table size (the default is 256).
 
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 618a6367c9..4627bbc4e6 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -183,6 +183,7 @@
 #
 # A vduse-blk block export.
 #
+# @name: the name of VDUSE device (must be unique across the host).
 # @num-queues: the number of virtqueues. Defaults to 1.
 # @queue-size: the size of virtqueue. Defaults to 256.
 # @logical-block-size: Logical block size in bytes. Range [512, PAGE_SIZE]
@@ -192,7 +193,8 @@
 # Since: 7.1
 ##
 { 'struct': 'BlockExportOptionsVduseBlk',
-  'data': { '*num-queues': 'uint16',
+  'data': { 'name': 'str',
+            '*num-queues': 'uint16',
             '*queue-size': 'uint16',
             '*logical-block-size': 'size',
             '*serial': 'str' } }
@@ -320,8 +322,7 @@
 # Describes a block export, i.e. how single node should be exported on an
 # external interface.
 #
-# @id: A unique identifier for the block export (across the host for vduse-blk
-#      export type or across all export types for other types)
+# @id: A unique identifier for the block export (across all export types)
 #
 # @node-name: The node name of the block node to be exported (since: 5.2)
 #
diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c
index 4e18d3fc85..b8e910f220 100644
--- a/storage-daemon/qemu-storage-daemon.c
+++ b/storage-daemon/qemu-storage-daemon.c
@@ -123,12 +123,12 @@ static void help(void)
 #endif /* CONFIG_VHOST_USER_BLK_SERVER */
 #ifdef CONFIG_VDUSE_BLK_EXPORT
 "  --export [type=]vduse-blk,id=<id>,node-name=<node-name>\n"
-"           [,writable=on|off][,num-queues=<num-queues>]\n"
-"           [,queue-size=<queue-size>]\n"
+"           ,name=<vduse-name>[,writable=on|off]\n"
+"           [,num-queues=<num-queues>][,queue-size=<queue-size>]\n"
 "           [,logical-block-size=<logical-block-size>]\n"
 "           [,serial=<serial-number>]\n"
-"                         export the specified block node as a vduse-blk\n"
-"                         device using the id as the VDUSE device name\n"
+"                         export the specified block node as a\n"
+"                         vduse-blk device\n"
 "\n"
 #endif /* CONFIG_VDUSE_BLK_EXPORT */
 "  --monitor [chardev=]name[,mode=control][,pretty[=on|off]]\n"