On 6/11/20 11:26 AM, Vladimir Sementsov-Ogievskiy wrote:
The NBD spec was recently updated to clarify that max_block doesn't
relate to NBD_CMD_WRITE_ZEROES with NBD_CMD_FLAG_FAST_ZERO (which
mirrors Qemu flag BDRV_REQ_NO_FALLBACK).
bs->bl.max_write_zero_fast is zero by default which means using
max_pwrite_zeroes. Update nbd driver to allow larger requests with
BDRV_REQ_NO_FALLBACK.
Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
---
block/nbd.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block/nbd.c b/block/nbd.c
index 4ac23c8f62..b0584cf68d 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -1956,6 +1956,7 @@ static void nbd_refresh_limits(BlockDriverState *bs,
Error **errp)
bs->bl.request_alignment = min;
bs->bl.max_pdiscard = QEMU_ALIGN_DOWN(INT_MAX, min);
+ bs->bl.max_pwrite_zeroes_fast = bs->bl.max_pdiscard;
bs->bl.max_pwrite_zeroes = max;
Do we even need max_pwrite_zeroes_fast? Doesn't qemu behave correctly
if we just blindly assign max_pdiscard and max_pwrite_zeroes to the same
value near 2G?
bs->bl.max_transfer = max;
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
