block: change default of .has_zero_init to 0

.has_zero_init defaults to 1 for all formats and protocols.

this is a dangerous default since this means that all
new added drivers need to manually overwrite it to 0 if
they do not ensure that a device is zero initialized
after bdrv_create().

if a driver needs to explicitly set this value to
1 its easier to verify the correctness in the review process.

during review of the existing drivers it turned out
that ssh and gluster had a wrong default of 1.
both protocols support host_devices as backend
which are not by default zero initialized. this
wrong assumption will lead to possible corruption
if qemu-img convert is used to write to such a backend.

vpc and vmdk also defaulted to 1 altough they support
fixed respectively flat extends. this has to be addresses
in separate patches. both formats as well as the mentioned
ssh and gluster are turned to the default of 0 with this
patch for safety.

a similar problem with the wrong default existed for
iscsi most likely because the driver developer did
oversee the default value of 1.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block.c b/block.c
index 0898f6b4b6d32cd01dd9505f86fad20b7bb94667..6c493ad457d690f37d070068b86529cea07f36cb 100644 (file)
--- a/block.c
+++ b/block.c
@@ -2911,6 +2911,11 @@ void bdrv_flush_all(void)
     }
 }
 
+int bdrv_has_zero_init_1(BlockDriverState *bs)
+{
+    return 1;
+}
+
 int bdrv_has_zero_init(BlockDriverState *bs)
 {
     assert(bs->drv);
@@ -2919,7 +2924,8 @@ int bdrv_has_zero_init(BlockDriverState *bs)
         return bs->drv->bdrv_has_zero_init(bs);
     }
 
-    return 1;
+    /* safe default */
+    return 0;
 }
 
 typedef struct BdrvCoIsAllocatedData {

diff --git a/block/cow.c b/block/cow.c
index 9f94599661c5cc8280e1558277cf5315d7f4e66c..1cc2e89c7cd01a62223cdbca5c4d5e47e12c71d6 100644 (file)
--- a/block/cow.c
+++ b/block/cow.c
@@ -340,6 +340,7 @@ static BlockDriver bdrv_cow = {
     .bdrv_open      = cow_open,
     .bdrv_close     = cow_close,
     .bdrv_create    = cow_create,
+    .bdrv_has_zero_init     = bdrv_has_zero_init_1,
 
     .bdrv_read              = cow_co_read,
     .bdrv_write             = cow_co_write,

diff --git a/block/qcow.c b/block/qcow.c
index e2a64c79b13b2e1eff0f76d21418920790301df8..5239bd68f1cdde80f521702a0ba95bc371ac56ad 100644 (file)
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -892,6 +892,7 @@ static BlockDriver bdrv_qcow = {
     .bdrv_close                = qcow_close,
     .bdrv_reopen_prepare = qcow_reopen_prepare,
     .bdrv_create       = qcow_create,
+    .bdrv_has_zero_init     = bdrv_has_zero_init_1,
 
     .bdrv_co_readv          = qcow_co_readv,
     .bdrv_co_writev         = qcow_co_writev,

diff --git a/block/qcow2.c b/block/qcow2.c
index 9383990193f66f3cef384e80f0707a1b0e892408..0eceefe2cd9e5d4ee56518847cffeaab4377efea 100644 (file)
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1785,6 +1785,7 @@ static BlockDriver bdrv_qcow2 = {
     .bdrv_close         = qcow2_close,
     .bdrv_reopen_prepare  = qcow2_reopen_prepare,
     .bdrv_create        = qcow2_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
     .bdrv_co_is_allocated = qcow2_co_is_allocated,
     .bdrv_set_key       = qcow2_set_key,
     .bdrv_make_empty    = qcow2_make_empty,

diff --git a/block/qed.c b/block/qed.c
index 4651403fef40f7a968ab5e1248d9c637e20fb492..f767b0528ce0f20069fbfa7059273517a37b8751 100644 (file)
--- a/block/qed.c
+++ b/block/qed.c
@@ -1574,6 +1574,7 @@ static BlockDriver bdrv_qed = {
     .bdrv_close               = bdrv_qed_close,
     .bdrv_reopen_prepare      = bdrv_qed_reopen_prepare,
     .bdrv_create              = bdrv_qed_create,
+    .bdrv_has_zero_init       = bdrv_has_zero_init_1,
     .bdrv_co_is_allocated     = bdrv_qed_co_is_allocated,
     .bdrv_make_empty          = bdrv_qed_make_empty,
     .bdrv_aio_readv           = bdrv_qed_aio_readv,

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 90ce9f86af9e63fdf3aeb26892bee1e893361cdf..ba721d3f5bd98a6b62791c2e20dbf2894021ad76 100644 (file)
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1199,6 +1199,7 @@ static BlockDriver bdrv_file = {
     .bdrv_reopen_abort = raw_reopen_abort,
     .bdrv_close = raw_close,
     .bdrv_create = raw_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
     .bdrv_co_is_allocated = raw_co_is_allocated,
 
     .bdrv_aio_readv = raw_aio_readv,
@@ -1527,11 +1528,6 @@ 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",
@@ -1544,7 +1540,6 @@ static BlockDriver bdrv_host_device = {
     .bdrv_reopen_abort   = raw_reopen_abort,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_aio_readv    = raw_aio_readv,
     .bdrv_aio_writev   = raw_aio_writev,
@@ -1669,7 +1664,6 @@ static BlockDriver bdrv_host_floppy = {
     .bdrv_reopen_abort   = raw_reopen_abort,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_aio_readv     = raw_aio_readv,
     .bdrv_aio_writev    = raw_aio_writev,
@@ -1771,7 +1765,6 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_reopen_abort   = raw_reopen_abort,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_aio_readv     = raw_aio_readv,
     .bdrv_aio_writev    = raw_aio_writev,
@@ -1893,7 +1886,6 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_reopen_abort   = raw_reopen_abort,
     .bdrv_create        = hdev_create,
     .create_options     = raw_create_options,
-    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_aio_readv     = raw_aio_readv,
     .bdrv_aio_writev    = raw_aio_writev,

diff --git a/block/raw-win32.c b/block/raw-win32.c
index 7c03b6df52e1bcf820cf4599774b61a6612aefae..9b5b2af4e83dbc590b74703306fc74d41b8755b3 100644 (file)
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -459,6 +459,7 @@ static BlockDriver bdrv_file = {
     .bdrv_file_open    = raw_open,
     .bdrv_close                = raw_close,
     .bdrv_create       = raw_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
 
     .bdrv_aio_readv     = raw_aio_readv,
     .bdrv_aio_writev    = raw_aio_writev,
@@ -570,11 +571,6 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags)
     return 0;
 }
 
-static int hdev_has_zero_init(BlockDriverState *bs)
-{
-    return 0;
-}
-
 static BlockDriver bdrv_host_device = {
     .format_name       = "host_device",
     .protocol_name     = "host_device",
@@ -582,7 +578,6 @@ static BlockDriver bdrv_host_device = {
     .bdrv_probe_device = hdev_probe_device,
     .bdrv_file_open    = hdev_open,
     .bdrv_close                = raw_close,
-    .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_aio_readv     = raw_aio_readv,
     .bdrv_aio_writev    = raw_aio_writev,

diff --git a/block/rbd.c b/block/rbd.c
index 0f2608b2876b66b00da4cacf557f043f8b23f987..cb71751218298cc0dcba4e48cc5f1d10893b597e 100644 (file)
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -996,6 +996,7 @@ static BlockDriver bdrv_rbd = {
     .bdrv_file_open     = qemu_rbd_open,
     .bdrv_close         = qemu_rbd_close,
     .bdrv_create        = qemu_rbd_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
     .bdrv_get_info      = qemu_rbd_getinfo,
     .create_options     = qemu_rbd_create_options,
     .bdrv_getlength     = qemu_rbd_getlength,

diff --git a/block/sheepdog.c b/block/sheepdog.c
index 1b7c3f19b080b5bc9963a954fb7285fda9f86829..b397b5b4d3188f774a08d79b79b860e189770cca 100644 (file)
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -2401,6 +2401,7 @@ static BlockDriver bdrv_sheepdog_unix = {
     .bdrv_file_open = sd_open,
     .bdrv_close     = sd_close,
     .bdrv_create    = sd_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
     .bdrv_getlength = sd_getlength,
     .bdrv_truncate  = sd_truncate,
 

diff --git a/block/vdi.c b/block/vdi.c
index 2662d89af6bd5776b57d44c11dd306af568615df..8a915257e82d162200b23c780e067ed40e18d642 100644 (file)
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -779,6 +779,7 @@ static BlockDriver bdrv_vdi = {
     .bdrv_close = vdi_close,
     .bdrv_reopen_prepare = vdi_reopen_prepare,
     .bdrv_create = vdi_create,
+    .bdrv_has_zero_init = bdrv_has_zero_init_1,
     .bdrv_co_is_allocated = vdi_co_is_allocated,
     .bdrv_make_empty = vdi_make_empty,
 

diff --git a/include/block/block.h b/include/block/block.h
index 2307f67b0ec69afd7f38510635b735f5e978aa14..dd8eca1be16e26c95fac96d1c9adfa1866ec3a56 100644 (file)
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -272,6 +272,7 @@ void bdrv_drain_all(void);
 
 int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
 int bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
+int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
 int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
                       int *pnum);