[PULL 30/30] block: Drop unused .bdrv_has_zero_init_truncate

[Kevin Wolf <kwolf@redhat.com>]

From: Eric Blake <eblake@redhat.com>

Now that there are no clients of bdrv_has_zero_init_truncate, none of
the drivers need to worry about providing it.

What's more, this eliminates a source of some confusion: a literal
reading of the documentation as written in ceaca56f and implemented in
commit 1dcaf527 claims that a driver which returns 0 for
bdrv_has_zero_init_truncate() must not return 1 for
bdrv_has_zero_init(); this condition was violated for parallels, qcow,
and sometimes for vdi, although in practice it did not matter since
those drivers also lacked .bdrv_co_truncate.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200428202905.770727-10-eblake@redhat.com>
Acked-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block.h     |  1 -
 include/block/block_int.h |  7 -------
 block.c                   | 21 ---------------------
 block/file-posix.c        |  1 -
 block/file-win32.c        |  1 -
 block/nfs.c               |  1 -
 block/qcow2.c             |  1 -
 block/qed.c               |  1 -
 block/raw-format.c        |  6 ------
 block/rbd.c               |  1 -
 block/sheepdog.c          |  3 ---
 block/ssh.c               |  1 -
 12 files changed, 45 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index 8b62429aa4..4de8d8f8a6 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -430,7 +430,6 @@ int bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
 int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
 int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
-int bdrv_has_zero_init_truncate(BlockDriverState *bs);
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 92335f33c7..df6d0273d6 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -449,16 +449,9 @@ struct BlockDriver {
     /*
      * Returns 1 if newly created images are guaranteed to contain only
      * zeros, 0 otherwise.
-     * Must return 0 if .bdrv_has_zero_init_truncate() returns 0.
      */
     int (*bdrv_has_zero_init)(BlockDriverState *bs);
 
-    /*
-     * Returns 1 if new areas added by growing the image with
-     * PREALLOC_MODE_OFF contain only zeros, 0 otherwise.
-     */
-    int (*bdrv_has_zero_init_truncate)(BlockDriverState *bs);
-
     /* Remove fd handlers, timers, and other event loop callbacks so the event
      * loop is no longer in use.  Called with no in-flight requests and in
      * depth-first traversal order with parents before child nodes.
diff --git a/block.c b/block.c
index cf5c19b1db..0653ccb913 100644
--- a/block.c
+++ b/block.c
@@ -5284,27 +5284,6 @@ int bdrv_has_zero_init(BlockDriverState *bs)
     return 0;
 }
 
-int bdrv_has_zero_init_truncate(BlockDriverState *bs)
-{
-    if (!bs->drv) {
-        return 0;
-    }
-
-    if (bs->backing) {
-        /* Depends on the backing image length, but better safe than sorry */
-        return 0;
-    }
-    if (bs->drv->bdrv_has_zero_init_truncate) {
-        return bs->drv->bdrv_has_zero_init_truncate(bs);
-    }
-    if (bs->file && bs->drv->is_filter) {
-        return bdrv_has_zero_init_truncate(bs->file->bs);
-    }
-
-    /* safe default */
-    return 0;
-}
-
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs)
 {
     BlockDriverInfo bdi;
diff --git a/block/file-posix.c b/block/file-posix.c
index 05e094be29..3ab8f5a0fa 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -3100,7 +3100,6 @@ BlockDriver bdrv_file = {
     .bdrv_co_create = raw_co_create,
     .bdrv_co_create_opts = raw_co_create_opts,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status = raw_co_block_status,
     .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
     .bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,
diff --git a/block/file-win32.c b/block/file-win32.c
index fa569685d8..221aaf713e 100644
--- a/block/file-win32.c
+++ b/block/file-win32.c
@@ -641,7 +641,6 @@ BlockDriver bdrv_file = {
     .bdrv_close         = raw_close,
     .bdrv_co_create_opts = raw_co_create_opts,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
 
     .bdrv_aio_preadv    = raw_aio_preadv,
     .bdrv_aio_pwritev   = raw_aio_pwritev,
diff --git a/block/nfs.c b/block/nfs.c
index 76daa7c9f6..b1718d125a 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -872,7 +872,6 @@ static BlockDriver bdrv_nfs = {
     .create_opts                    = &nfs_create_opts,
 
     .bdrv_has_zero_init             = nfs_has_zero_init,
-    .bdrv_has_zero_init_truncate    = nfs_has_zero_init,
     .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
     .bdrv_co_truncate               = nfs_file_co_truncate,
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 11903fb547..1ad95ff048 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5621,7 +5621,6 @@ BlockDriver bdrv_qcow2 = {
     .bdrv_co_create_opts  = qcow2_co_create_opts,
     .bdrv_co_create       = qcow2_co_create,
     .bdrv_has_zero_init   = qcow2_has_zero_init,
-    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status = qcow2_co_block_status,
 
     .bdrv_co_preadv_part    = qcow2_co_preadv_part,
diff --git a/block/qed.c b/block/qed.c
index fb609cfba1..5da9726518 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1675,7 +1675,6 @@ static BlockDriver bdrv_qed = {
     .bdrv_co_create           = bdrv_qed_co_create,
     .bdrv_co_create_opts      = bdrv_qed_co_create_opts,
     .bdrv_has_zero_init       = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status     = bdrv_qed_co_block_status,
     .bdrv_co_readv            = bdrv_qed_co_readv,
     .bdrv_co_writev           = bdrv_qed_co_writev,
diff --git a/block/raw-format.c b/block/raw-format.c
index 351f2d91c6..9108e43696 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -414,11 +414,6 @@ static int raw_has_zero_init(BlockDriverState *bs)
     return bdrv_has_zero_init(bs->file->bs);
 }
 
-static int raw_has_zero_init_truncate(BlockDriverState *bs)
-{
-    return bdrv_has_zero_init_truncate(bs->file->bs);
-}
-
 static int coroutine_fn raw_co_create_opts(BlockDriver *drv,
                                            const char *filename,
                                            QemuOpts *opts,
@@ -582,7 +577,6 @@ BlockDriver bdrv_raw = {
     .bdrv_co_ioctl        = &raw_co_ioctl,
     .create_opts          = &raw_create_opts,
     .bdrv_has_zero_init   = &raw_has_zero_init,
-    .bdrv_has_zero_init_truncate = &raw_has_zero_init_truncate,
     .strong_runtime_opts  = raw_strong_runtime_opts,
     .mutable_opts         = mutable_opts,
 };
diff --git a/block/rbd.c b/block/rbd.c
index 331c45adb2..617553b022 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -1313,7 +1313,6 @@ static BlockDriver bdrv_rbd = {
     .bdrv_co_create         = qemu_rbd_co_create,
     .bdrv_co_create_opts    = qemu_rbd_co_create_opts,
     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_get_info          = qemu_rbd_getinfo,
     .create_opts            = &qemu_rbd_create_opts,
     .bdrv_getlength         = qemu_rbd_getlength,
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 739e6dee30..27a30d17f4 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -3226,7 +3226,6 @@ static BlockDriver bdrv_sheepdog = {
     .bdrv_co_create               = sd_co_create,
     .bdrv_co_create_opts          = sd_co_create_opts,
     .bdrv_has_zero_init           = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate  = bdrv_has_zero_init_1,
     .bdrv_getlength               = sd_getlength,
     .bdrv_get_allocated_file_size = sd_get_allocated_file_size,
     .bdrv_co_truncate             = sd_co_truncate,
@@ -3265,7 +3264,6 @@ static BlockDriver bdrv_sheepdog_tcp = {
     .bdrv_co_create               = sd_co_create,
     .bdrv_co_create_opts          = sd_co_create_opts,
     .bdrv_has_zero_init           = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate  = bdrv_has_zero_init_1,
     .bdrv_getlength               = sd_getlength,
     .bdrv_get_allocated_file_size = sd_get_allocated_file_size,
     .bdrv_co_truncate             = sd_co_truncate,
@@ -3304,7 +3302,6 @@ static BlockDriver bdrv_sheepdog_unix = {
     .bdrv_co_create               = sd_co_create,
     .bdrv_co_create_opts          = sd_co_create_opts,
     .bdrv_has_zero_init           = bdrv_has_zero_init_1,
-    .bdrv_has_zero_init_truncate  = bdrv_has_zero_init_1,
     .bdrv_getlength               = sd_getlength,
     .bdrv_get_allocated_file_size = sd_get_allocated_file_size,
     .bdrv_co_truncate             = sd_co_truncate,
diff --git a/block/ssh.c b/block/ssh.c
index f9e08a4900..098dbe03c1 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -1397,7 +1397,6 @@ static BlockDriver bdrv_ssh = {
     .bdrv_co_create_opts          = ssh_co_create_opts,
     .bdrv_close                   = ssh_close,
     .bdrv_has_zero_init           = ssh_has_zero_init,
-    .bdrv_has_zero_init_truncate  = ssh_has_zero_init,
     .bdrv_co_readv                = ssh_co_readv,
     .bdrv_co_writev               = ssh_co_writev,
     .bdrv_getlength               = ssh_getlength,
-- 
2.25.3