block/export: Add BlockExport infrastructure and block-export-add

We want to have a common set of commands for all types of block exports.
Currently, this is only NBD, but we're going to add more types.

This patch adds the basic BlockExport and BlockExportDriver structs and
a QMP command block-export-add that creates a new export based on the
given BlockExportOptions.

qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-5-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/export/export.c b/block/export/export.c
new file mode 100644 (file)
index 0000000..fd65541
--- /dev/null
+++ b/block/export/export.c
@@ -0,0 +1,48 @@
+/*
+ * Common block export infrastructure
+ *
+ * Copyright (c) 2012, 2020 Red Hat, Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include "block/export.h"
+#include "block/nbd.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-block-export.h"
+
+static const BlockExportDriver *blk_exp_drivers[] = {
+    &blk_exp_nbd,
+};
+
+static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
+{
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
+        if (blk_exp_drivers[i]->type == type) {
+            return blk_exp_drivers[i];
+        }
+    }
+    return NULL;
+}
+
+void qmp_block_export_add(BlockExportOptions *export, Error **errp)
+{
+    const BlockExportDriver *drv;
+
+    drv = blk_exp_find_driver(export->type);
+    if (!drv) {
+        error_setg(errp, "No driver found for the requested export type");
+        return;
+    }
+
+    drv->create(export, errp);
+}

diff --git a/block/export/meson.build b/block/export/meson.build
new file mode 100644 (file)
index 0000000..558ef35
--- /dev/null
+++ b/block/export/meson.build
@@ -0,0 +1 @@
+block_ss.add(files('export.c'))

diff --git a/block/meson.build b/block/meson.build
index a3e56b7cd11d202cb1d8a14bfac8019cc0ee40ca..0b38dc36f766edeaf6bb87a4b6bca30ad3cc0028 100644 (file)
--- a/block/meson.build
+++ b/block/meson.build
@@ -110,6 +110,8 @@ block_ss.add(module_block_h)
 block_ss.add(files('stream.c'))
 
 softmmu_ss.add(files('qapi-sysemu.c'))
+
+subdir('export')
 subdir('monitor')
 
 modules += {'block': block_modules}

diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 98ee1b61701cece7bb0c475705c96e8b063bd695..47b04f166ae3b83ad334812f0bae52fa63a4ed36 100644 (file)
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -148,17 +148,20 @@ void qmp_nbd_server_start(SocketAddressLegacy *addr,
     qapi_free_SocketAddress(addr_flat);
 }
 
-void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
+BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
 {
+    BlockExportOptionsNbd *arg = &exp_args->u.nbd;
     BlockDriverState *bs = NULL;
     BlockBackend *on_eject_blk;
-    NBDExport *exp;
+    NBDExport *exp = NULL;
     int64_t len;
     AioContext *aio_context;
 
+    assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
+
     if (!nbd_server) {
         error_setg(errp, "NBD server not running");
-        return;
+        return NULL;
     }
 
     if (!arg->has_name) {
@@ -167,24 +170,24 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
 
     if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
         error_setg(errp, "export name '%s' too long", arg->name);
-        return;
+        return NULL;
     }
 
     if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
         error_setg(errp, "description '%s' too long", arg->description);
-        return;
+        return NULL;
     }
 
     if (nbd_export_find(arg->name)) {
         error_setg(errp, "NBD server already has export named '%s'", arg->name);
-        return;
+        return NULL;
     }
 
     on_eject_blk = blk_by_name(arg->device);
 
     bs = bdrv_lookup_bs(arg->device, arg->device, errp);
     if (!bs) {
-        return;
+        return NULL;
     }
 
     aio_context = bdrv_get_aio_context(bs);
@@ -217,6 +220,17 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
 
  out:
     aio_context_release(aio_context);
+    /* TODO Remove the cast: nbd_export_new() will return a BlockExport. */
+    return (BlockExport*) exp;
+}
+
+void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
+{
+    BlockExportOptions export = {
+        .type = BLOCK_EXPORT_TYPE_NBD,
+        .u.nbd = *arg,
+    };
+    qmp_block_export_add(&export, errp);
 }
 
 void qmp_nbd_server_remove(const char *name,

diff --git a/include/block/export.h b/include/block/export.h
new file mode 100644 (file)
index 0000000..42e3c05
--- /dev/null
+++ b/include/block/export.h
@@ -0,0 +1,33 @@
+/*
+ * Declarations for block exports
+ *
+ * Copyright (c) 2012, 2020 Red Hat, Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef BLOCK_EXPORT_H
+#define BLOCK_EXPORT_H
+
+#include "qapi/qapi-types-block-export.h"
+
+typedef struct BlockExport BlockExport;
+
+typedef struct BlockExportDriver {
+    /* The export type that this driver services */
+    BlockExportType type;
+
+    /* Creates and starts a new block export */
+    BlockExport *(*create)(BlockExportOptions *, Error **);
+} BlockExportDriver;
+
+struct BlockExport {
+    const BlockExportDriver *drv;
+};
+
+#endif

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 262f6da2ceca874b12399077ac994e70efd5941d..7698453fb22ad9aa0fd43f99715d7b78641b4d4f 100644 (file)
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -20,11 +20,13 @@
 #ifndef NBD_H
 #define NBD_H
 
-#include "qapi/qapi-types-block-export.h"
+#include "block/export.h"
 #include "io/channel-socket.h"
 #include "crypto/tlscreds.h"
 #include "qapi/error.h"
 
+extern const BlockExportDriver blk_exp_nbd;
+
 /* Handshake phase structs - this struct is passed on the wire */
 
 struct NBDOption {
@@ -328,6 +330,7 @@ int nbd_errno_to_system_errno(int err);
 typedef struct NBDExport NBDExport;
 typedef struct NBDClient NBDClient;
 
+BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp);
 NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
                           uint64_t size, const char *name, const char *desc,
                           const char *bitmap, bool readonly, bool shared,

diff --git a/meson.build b/meson.build
index 3161c1f037ae044d2f1ecd0eadf327d9d7dd2443..0f0cc21d16f4276f4075edfd38741c66fc3fec8c 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -970,6 +970,7 @@ subdir('dump')
 
 block_ss.add(files(
   'block.c',
+  'blockdev-nbd.c',
   'blockjob.c',
   'job.c',
   'qemu-io-cmds.c',
@@ -982,7 +983,6 @@ subdir('block')
 
 blockdev_ss.add(files(
   'blockdev.c',
-  'blockdev-nbd.c',
   'iothread.c',
   'job-qmp.c',
 ))

diff --git a/nbd/server.c b/nbd/server.c
index bd53f7baea6a97a338aa7fe7243155a7ea7bf9b4..f5af93c25351eb8fb45523f38ef6eafdd942aa06 100644 (file)
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -18,6 +18,8 @@
  */
 
 #include "qemu/osdep.h"
+
+#include "block/export.h"
 #include "qapi/error.h"
 #include "qemu/queue.h"
 #include "trace.h"
@@ -80,6 +82,7 @@ struct NBDRequestData {
 };
 
 struct NBDExport {
+    BlockExport common;
     int refcount;
     void (*close)(NBDExport *exp);
 
@@ -1512,10 +1515,15 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
 {
     AioContext *ctx;
     BlockBackend *blk;
-    NBDExport *exp = g_new0(NBDExport, 1);
+    NBDExport *exp;
     uint64_t perm;
     int ret;
 
+    exp = g_new0(NBDExport, 1);
+    exp->common = (BlockExport) {
+        .drv = &blk_exp_nbd,
+    };
+
     /*
      * NBD exports are used for non-shared storage migration.  Make sure
      * that BDRV_O_INACTIVE is cleared and the image is ready for write
@@ -1731,6 +1739,11 @@ void nbd_export_put(NBDExport *exp)
     }
 }
 
+const BlockExportDriver blk_exp_nbd = {
+    .type               = BLOCK_EXPORT_TYPE_NBD,
+    .create             = nbd_export_create,
+};
+
 void nbd_export_close_all(void)
 {
     NBDExport *exp, *next;

diff --git a/qapi/block-export.json b/qapi/block-export.json
index 6ac3a631233d912439d74484664fcd72e9338b1e..5890a942199857e811c3f6e9cbf0840133be2140 100644 (file)
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -172,3 +172,13 @@
   'data': {
       'nbd': 'BlockExportOptionsNbd'
    } }
+
+##
+# @block-export-add:
+#
+# Creates a new block export.
+#
+# Since: 5.2
+##
+{ 'command': 'block-export-add',
+  'data': 'BlockExportOptions', 'boxed': true }