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block/blkio: Tolerate device size changes

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Some libblkio drivers may be able to work with regular files (e.g.,
io_uring) or otherwise resizable devices. Conservatively set
BlockDriver::has_variable_length to true to ensure bdrv_nb_sectors()
always gives up-to-date results.

Also implement BlockDriver::bdrv_co_truncate for the case where no
preallocation is needed and the device already has a size compatible
with what was requested.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Message-id: 20221029122031.975273-1-afaria@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Alberto Faria 2022-10-29 13:20:31 +01:00 committed by Stefan Hajnoczi
parent 03d9e4c0db
commit 4c8f4fda05
1 changed files with 27 additions and 0 deletions
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27
block/blkio.c
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@ -848,6 +848,31 @@ static int64_t blkio_getlength(BlockDriverState *bs)
return capacity;
}
static int coroutine_fn blkio_truncate(BlockDriverState *bs, int64_t offset,
bool exact, PreallocMode prealloc,
BdrvRequestFlags flags, Error **errp)
{
int64_t current_length;
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
current_length = blkio_getlength(bs);
if (offset > current_length) {
error_setg(errp, "Cannot grow device");
return -EINVAL;
} else if (exact && offset != current_length) {
error_setg(errp, "Cannot resize device");
return -ENOTSUP;
}
return 0;
}
static int blkio_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
return 0;
@ -963,10 +988,12 @@ static void blkio_refresh_limits(BlockDriverState *bs, Error **errp)
{ \
.format_name = name, \
.protocol_name = name, \
.has_variable_length = true, \
.instance_size = sizeof(BDRVBlkioState), \
.bdrv_file_open = blkio_file_open, \
.bdrv_close = blkio_close, \
.bdrv_getlength = blkio_getlength, \
.bdrv_co_truncate = blkio_truncate, \
.bdrv_get_info = blkio_get_info, \
.bdrv_attach_aio_context = blkio_attach_aio_context, \
.bdrv_detach_aio_context = blkio_detach_aio_context, \