From: Alberto Faria <afa...@redhat.com>
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 <afa...@redhat.com>
Message-id: 20221029122031.975273-1-afa...@redhat.com
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block/blkio.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/block/blkio.c b/block/blkio.c
index f55eb774b4..d850506acd 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -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, \
--
2.38.1
