blkdebug: Make required alignment configurable

The new 'align' option of blkdebug can be used in order to emulate
backends with a required 4k alignment on hosts which only really require
512 byte alignment.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/blkdebug.c

@@ -364,6 +364,11 @@ static QemuOptsList runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "[internal use only, will be removed]",
         },
+        {
+            .name = "align",
+            .type = QEMU_OPT_SIZE,
+            .help = "Required alignment in bytes",
+        },
         { /* end of list */ }
     },
 };
@@ -375,6 +380,7 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     QemuOpts *opts;
     Error *local_err = NULL;
     const char *config;
+    uint64_t align;
     int ret;
 
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
@@ -403,6 +409,16 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     }
 
+    /* Set request alignment */
+    align = qemu_opt_get_size(opts, "align", bs->request_alignment);
+    if (align > 0 && align < INT_MAX && !(align & (align - 1))) {
+        bs->request_alignment = align;
+    } else {
+        error_setg(errp, "Invalid alignment");
+        ret = -EINVAL;
+        goto fail;
+    }
+
     ret = 0;
 fail:
     qemu_opts_del(opts);

qapi-schema.json

@@ -4321,6 +4321,8 @@
 #
 # @config:          #optional filename of the configuration file
 #
+# @align:           #optional required alignment for requests in bytes
+#
 # @inject-error:    #optional array of error injection descriptions
 #
 # @set-state:       #optional array of state-change descriptions
@@ -4330,6 +4332,7 @@
 { 'type': 'BlockdevOptionsBlkdebug',
   'data': { 'image': 'BlockdevRef',
             '*config': 'str',
+            '*align': 'int',
             '*inject-error': ['BlkdebugInjectErrorOptions'],
             '*set-state': ['BlkdebugSetStateOptions'] } }