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block: Do not truncate file node when formatting

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There is no reason why the format drivers need to truncate the protocol
node when formatting it.  When using the old .bdrv_co_create_ops()
interface, the file will be created with no size option anyway, which
generally gives it a size of 0.  (Exceptions are block devices, which
cannot be truncated anyway.)

When using blockdev-create, the user must have given the file node some
size anyway, so there is no reason why we should override that.

qed is an exception, it needs the file to start completely empty (as
explained by c743849bee).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-4-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-09-18 11:51:39 +02:00
parent bb8160eb78
commit 26536c7fc2
3 changed files with 0 additions and 16 deletions
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5
block/parallels.c
View File

@ -563,11 +563,6 @@ static int coroutine_fn parallels_co_create(BlockdevCreateOptions* opts,
blk_set_allow_write_beyond_eof(blk, true);
/* Create image format */
ret = blk_truncate(blk, 0, PREALLOC_MODE_OFF, errp);
if (ret < 0) {
goto out;
}
bat_entries = DIV_ROUND_UP(total_size, cl_size);
bat_sectors = DIV_ROUND_UP(bat_entry_off(bat_entries), cl_size);
bat_sectors = (bat_sectors * cl_size) >> BDRV_SECTOR_BITS;

5
block/qcow.c
View File

@ -858,11 +858,6 @@ static int coroutine_fn qcow_co_create(BlockdevCreateOptions *opts,
blk_set_allow_write_beyond_eof(qcow_blk, true);
/* Create image format */
ret = blk_truncate(qcow_blk, 0, PREALLOC_MODE_OFF, errp);
if (ret < 0) {
goto exit;
}
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);

6
block/qcow2.c
View File

@ -3391,12 +3391,6 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
}
blk_set_allow_write_beyond_eof(blk, true);
/* Clear the protocol layer and preallocate it if necessary */
ret = blk_truncate(blk, 0, PREALLOC_MODE_OFF, errp);
if (ret < 0) {
goto out;
}
/* Write the header */
QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
header = g_malloc0(cluster_size);