block/export: Add 'id' option to block-export-add

We'll need an id to identify block exports in monitor commands. This
adds one.

Note that this is different from the 'name' option in the NBD server,
which is the externally visible export name. While block export ids need
to be unique in the whole process, export names must be unique only for
the same server. Different export types or (potentially in the future)
multiple NBD servers can have the same export name externally, but still
need different block export ids internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-19-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/block/export/export.c b/block/export/export.c
index e94a68c..7a4a784 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -19,6 +19,7 @@
 #include "block/nbd.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-block-export.h"
+#include "qemu/id.h"
 
 static const BlockExportDriver *blk_exp_drivers[] = {
     &blk_exp_nbd,
@@ -28,6 +29,19 @@ static const BlockExportDriver *blk_exp_drivers[] = {
 static QLIST_HEAD(, BlockExport) block_exports =
     QLIST_HEAD_INITIALIZER(block_exports);
 
+static BlockExport *blk_exp_find(const char *id)
+{
+    BlockExport *exp;
+
+    QLIST_FOREACH(exp, &block_exports, next) {
+        if (strcmp(id, exp->id) == 0) {
+            return exp;
+        }
+    }
+
+    return NULL;
+}
+
 static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
 {
     int i;
@@ -46,6 +60,15 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     BlockExport *exp;
     int ret;
 
+    if (!id_wellformed(export->id)) {
+        error_setg(errp, "Invalid block export id");
+        return NULL;
+    }
+    if (blk_exp_find(export->id)) {
+        error_setg(errp, "Block export id '%s' is already in use", export->id);
+        return NULL;
+    }
+
     drv = blk_exp_find_driver(export->type);
     if (!drv) {
         error_setg(errp, "No driver found for the requested export type");
@@ -57,10 +80,12 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     *exp = (BlockExport) {
         .drv        = drv,
         .refcount   = 1,
+        .id         = g_strdup(export->id),
     };
 
     ret = drv->create(exp, export, errp);
     if (ret < 0) {
+        g_free(exp->id);
         g_free(exp);
         return NULL;
     }
@@ -87,6 +112,7 @@ static void blk_exp_delete_bh(void *opaque)
     assert(exp->refcount == 0);
     QLIST_REMOVE(exp, next);
     exp->drv->delete(exp);
+    g_free(exp->id);
     g_free(exp);
 
     aio_context_release(aio_context);