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-rw-r--r--block/nbd-client.c39
1 files changed, 38 insertions, 1 deletions
diff --git a/block/nbd-client.c b/block/nbd-client.c
index 3edb508f66..409c2171bc 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -848,6 +848,25 @@ int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
if (!bytes) {
return 0;
}
+ /*
+ * Work around the fact that the block layer doesn't do
+ * byte-accurate sizing yet - if the read exceeds the server's
+ * advertised size because the block layer rounded size up, then
+ * truncate the request to the server and tail-pad with zero.
+ */
+ if (offset >= client->info.size) {
+ assert(bytes < BDRV_SECTOR_SIZE);
+ qemu_iovec_memset(qiov, 0, 0, bytes);
+ return 0;
+ }
+ if (offset + bytes > client->info.size) {
+ uint64_t slop = offset + bytes - client->info.size;
+
+ assert(slop < BDRV_SECTOR_SIZE);
+ qemu_iovec_memset(qiov, bytes - slop, 0, slop);
+ request.len -= slop;
+ }
+
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
return ret;
@@ -966,7 +985,8 @@ int coroutine_fn nbd_client_co_block_status(BlockDriverState *bs,
.from = offset,
.len = MIN(MIN_NON_ZERO(QEMU_ALIGN_DOWN(INT_MAX,
bs->bl.request_alignment),
- client->info.max_block), bytes),
+ client->info.max_block),
+ MIN(bytes, client->info.size - offset)),
.flags = NBD_CMD_FLAG_REQ_ONE,
};
@@ -977,6 +997,23 @@ int coroutine_fn nbd_client_co_block_status(BlockDriverState *bs,
return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
}
+ /*
+ * Work around the fact that the block layer doesn't do
+ * byte-accurate sizing yet - if the status request exceeds the
+ * server's advertised size because the block layer rounded size
+ * up, we truncated the request to the server (above), or are
+ * called on just the hole.
+ */
+ if (offset >= client->info.size) {
+ *pnum = bytes;
+ assert(bytes < BDRV_SECTOR_SIZE);
+ /* Intentionally don't report offset_valid for the hole */
+ return BDRV_BLOCK_ZERO;
+ }
+
+ if (client->info.min_block) {
+ assert(QEMU_IS_ALIGNED(request.len, client->info.min_block));
+ }
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
return ret;