[Qemu-devel] [PATCH] block: Fix bdrv_has_zero_init

[Kevin Wolf]

Assuming that any image on a block device is not properly zero-initialized is
actually wrong: Only raw images have this problem. Any other image format
shouldn't care about it, they initialize everything properly themselves.

Signed-off-by: Kevin Wolf <address@hidden>
---
 block.c           |    6 ++----
 block/raw-posix.c |   13 +++++++++----
 block/raw-win32.c |    6 ++++++
 block/raw.c       |    6 ++++++
 block_int.h       |    7 +++++--
 5 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/block.c b/block.c
index be75832..98da39a 100644
--- a/block.c
+++ b/block.c
@@ -1477,10 +1477,8 @@ int bdrv_has_zero_init(BlockDriverState *bs)
 {
     assert(bs->drv);
 
-    if (bs->drv->no_zero_init) {
-        return 0;
-    } else if (bs->file) {
-        return bdrv_has_zero_init(bs->file);
+    if (bs->drv->bdrv_has_zero_init) {
+        return bs->drv->bdrv_has_zero_init(bs);
     }
 
     return 1;
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 8f84a37..240d84d 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -993,6 +993,11 @@ static int hdev_create(const char *filename, 
QEMUOptionParameter *options)
     return ret;
 }
 
+static int hdev_has_zero_init(BlockDriverState *bs)
+{
+    return 0;
+}
+
 static BlockDriver bdrv_host_device = {
     .format_name        = "host_device",
     .protocol_name        = "host_device",
@@ -1002,7 +1007,7 @@ static BlockDriver bdrv_host_device = {
     .bdrv_close         = raw_close,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .no_zero_init       = 1,
+    .bdrv_has_zero_init = hdev_has_zero_init,
     .bdrv_flush         = raw_flush,
 
     .bdrv_aio_readv    = raw_aio_readv,
@@ -1117,7 +1122,7 @@ static BlockDriver bdrv_host_floppy = {
     .bdrv_close         = raw_close,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .no_zero_init       = 1,
+    .bdrv_has_zero_init = hdev_has_zero_init,
     .bdrv_flush         = raw_flush,
 
     .bdrv_aio_readv     = raw_aio_readv,
@@ -1222,7 +1227,7 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_close         = raw_close,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .no_zero_init       = 1,
+    .bdrv_has_zero_init = hdev_has_zero_init,
     .bdrv_flush         = raw_flush,
 
     .bdrv_aio_readv     = raw_aio_readv,
@@ -1345,7 +1350,7 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_close         = raw_close,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .no_zero_init       = 1,
+    .bdrv_has_zero_init = hdev_has_zero_init,
     .bdrv_flush         = raw_flush,
 
     .bdrv_aio_readv     = raw_aio_readv,
diff --git a/block/raw-win32.c b/block/raw-win32.c
index 745bbde..503ed39 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -394,6 +394,11 @@ static int raw_set_locked(BlockDriverState *bs, int locked)
 }
 #endif
 
+static int hdev_has_zero_init(BlockDriverState *bs)
+{
+    return 0;
+}
+
 static BlockDriver bdrv_host_device = {
     .format_name       = "host_device",
     .protocol_name     = "host_device",
@@ -402,6 +407,7 @@ static BlockDriver bdrv_host_device = {
     .bdrv_file_open    = hdev_open,
     .bdrv_close                = raw_close,
     .bdrv_flush                = raw_flush,
+    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_read         = raw_read,
     .bdrv_write                = raw_write,
diff --git a/block/raw.c b/block/raw.c
index 1414e77..61e6748 100644
--- a/block/raw.c
+++ b/block/raw.c
@@ -237,6 +237,11 @@ static QEMUOptionParameter raw_create_options[] = {
     { NULL }
 };
 
+static int raw_has_zero_init(BlockDriverState *bs)
+{
+    return bdrv_has_zero_init(bs->file);
+}
+
 static BlockDriver bdrv_raw = {
     .format_name        = "raw",
 
@@ -264,6 +269,7 @@ static BlockDriver bdrv_raw = {
 
     .bdrv_create        = raw_create,
     .create_options     = raw_create_options,
+    .bdrv_has_zero_init = raw_has_zero_init,
 };
 
 static void bdrv_raw_init(void)
diff --git a/block_int.h b/block_int.h
index f075a8c..7d5e751 100644
--- a/block_int.h
+++ b/block_int.h
@@ -127,8 +127,11 @@ struct BlockDriver {
 
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);
 
-    /* Set if newly created images are not guaranteed to contain only zeros */
-    int no_zero_init;
+    /*
+     * Returns 1 if newly created images are guaranteed to contain only
+     * zeros, 0 otherwise.
+     */
+    int (*bdrv_has_zero_init)(BlockDriverState *bs);
 
     QLIST_ENTRY(BlockDriver) list;
 };
-- 
1.7.1.1