From 692e01a27ccde4120f1371227d4011f668d67a76 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 12 Sep 2016 21:00:41 +0200
Subject: [PATCH] block: Parse 'detect-zeroes' in bdrv_open_common()

Amongst others, this means that you can now use the 'detect-zeroes'
option for non-top-level nodes in blockdev-add, like the QAPI schema
promises.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block.c    | 33 +++++++++++++++++++++++++++++++++
 blockdev.c |  9 +--------
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/block.c b/block.c
index 493ecf3137..1f1045738d 100644
--- a/block.c
+++ b/block.c
@@ -42,6 +42,7 @@
 #include "qapi-event.h"
 #include "qemu/cutils.h"
 #include "qemu/id.h"
+#include "qapi/util.h"
 
 #ifdef CONFIG_BSD
 #include <sys/ioctl.h>
@@ -954,6 +955,11 @@ static QemuOptsList bdrv_runtime_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "Node is opened in read-only mode",
         },
+        {
+            .name = "detect-zeroes",
+            .type = QEMU_OPT_STRING,
+            .help = "try to optimize zero writes (off, on, unmap)",
+        },
         { /* end of list */ }
     },
 };
@@ -970,6 +976,7 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
     const char *filename;
     const char *driver_name = NULL;
     const char *node_name = NULL;
+    const char *detect_zeroes;
     QemuOpts *opts;
     BlockDriver *drv;
     Error *local_err = NULL;
@@ -1038,6 +1045,32 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
         }
     }
 
+    detect_zeroes = qemu_opt_get(opts, "detect-zeroes");
+    if (detect_zeroes) {
+        BlockdevDetectZeroesOptions value =
+            qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
+                            detect_zeroes,
+                            BLOCKDEV_DETECT_ZEROES_OPTIONS__MAX,
+                            BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
+                            &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            ret = -EINVAL;
+            goto fail_opts;
+        }
+
+        if (value == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
+            !(bs->open_flags & BDRV_O_UNMAP))
+        {
+            error_setg(errp, "setting detect-zeroes to unmap is not allowed "
+                             "without setting discard operation to unmap");
+            ret = -EINVAL;
+            goto fail_opts;
+        }
+
+        bs->detect_zeroes = value;
+    }
+
     if (filename != NULL) {
         pstrcpy(bs->filename, sizeof(bs->filename), filename);
     } else {
diff --git a/blockdev.c b/blockdev.c
index 7820f42210..511260ce93 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -658,7 +658,6 @@ static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
     BlockDriverState *bs;
     QemuOpts *opts;
     Error *local_error = NULL;
-    BlockdevDetectZeroesOptions detect_zeroes;
     int bdrv_flags = 0;
 
     opts = qemu_opts_create(&qemu_root_bds_opts, NULL, 1, errp);
@@ -673,7 +672,7 @@ static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
     }
 
     extract_common_blockdev_options(opts, &bdrv_flags, NULL, NULL,
-                                    &detect_zeroes, &local_error);
+                                    NULL, &local_error);
     if (local_error) {
         error_propagate(errp, local_error);
         goto fail;
@@ -695,8 +694,6 @@ static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
         goto fail_no_bs_opts;
     }
 
-    bs->detect_zeroes = detect_zeroes;
-
 fail_no_bs_opts:
     qemu_opts_del(opts);
     return bs;
@@ -4136,10 +4133,6 @@ static QemuOptsList qemu_root_bds_opts = {
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",
-        },{
-            .name = "detect-zeroes",
-            .type = QEMU_OPT_STRING,
-            .help = "try to optimize zero writes (off, on, unmap)",
         },
         { /* end of list */ }
     },