[Qemu-devel] [PATCH v14 01/20] block: Add, parse and store "force-shared-write" option

[Fam Zheng <famz@redhat.com>]

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c                   | 9 +++++++++
 include/block/block.h     | 2 ++
 include/block/block_int.h | 1 +
 3 files changed, 12 insertions(+)

diff --git a/block.c b/block.c
index 1e668fb..f5c4e97 100644
--- a/block.c
+++ b/block.c
@@ -763,6 +763,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
      * the parent. */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+    qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARED_WRITE);
 
     /* Inherit the read-only option from the parent if it's not set */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
@@ -871,6 +872,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
      * which is only applied on the top level (BlockBackend) */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+    qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARED_WRITE);
 
     /* backing files always opened read-only */
     qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
@@ -1115,6 +1117,11 @@ QemuOptsList bdrv_runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "discard operation (ignore/off, unmap/on)",
         },
+        {
+            .name = BDRV_OPT_FORCE_SHARED_WRITE,
+            .type = QEMU_OPT_BOOL,
+            .help = "always accept other writers (default: off)",
+        },
         { /* end of list */ }
     },
 };
@@ -1154,6 +1161,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
     drv = bdrv_find_format(driver_name);
     assert(drv != NULL);
 
+    bs->force_shared_write = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARED_WRITE, false);
+
     if (file != NULL) {
         filename = blk_bs(file)->filename;
     } else {
diff --git a/include/block/block.h b/include/block/block.h
index 5ddc0cf..d3afb75 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -109,6 +109,8 @@ typedef struct HDGeometry {
 #define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush"
 #define BDRV_OPT_READ_ONLY      "read-only"
 #define BDRV_OPT_DISCARD        "discard"
+#define BDRV_OPT_FORCE_SHARED_WRITE \
+                                "force-shared-write"
 
 
 #define BDRV_SECTOR_BITS   9
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 59400bd..fb81692 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -518,6 +518,7 @@ struct BlockDriverState {
     bool valid_key; /* if true, a valid encryption key has been set */
     bool sg;        /* if true, the device is a /dev/sg* */
     bool probed;    /* if true, format was probed rather than specified */
+    bool force_shared_write; /* if true, always allow shared write perm. */
 
     BlockDriver *drv; /* NULL means no media */
     void *opaque;
-- 
2.9.3