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[Qemu-block] [PULL 9/9] nbd: Implement server use of NBD FAST_ZERO
From: |
Eric Blake |
Subject: |
[Qemu-block] [PULL 9/9] nbd: Implement server use of NBD FAST_ZERO |
Date: |
Thu, 5 Sep 2019 13:21:32 -0500 |
The server side is fairly straightforward: we can always advertise
support for detection of fast zero, and implement it by mapping the
request to the block layer BDRV_REQ_NO_FALLBACK.
Signed-off-by: Eric Blake <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
nbd/server.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index 4992148de1c4..28c3c8be854c 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1513,7 +1513,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t
dev_offset,
exp->nbdflags |= NBD_FLAG_CAN_MULTI_CONN;
}
} else {
- exp->nbdflags |= NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES;
+ exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
+ NBD_FLAG_SEND_FAST_ZERO);
}
assert(size <= INT64_MAX - dev_offset);
exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
@@ -2166,7 +2167,7 @@ static int nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
if (request->type == NBD_CMD_READ && client->structured_reply) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
- valid_flags |= NBD_CMD_FLAG_NO_HOLE;
+ valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
} else if (request->type == NBD_CMD_BLOCK_STATUS) {
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
}
@@ -2305,6 +2306,9 @@ static coroutine_fn int nbd_handle_request(NBDClient
*client,
if (!(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
flags |= BDRV_REQ_MAY_UNMAP;
}
+ if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
+ flags |= BDRV_REQ_NO_FALLBACK;
+ }
ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
request->len, flags);
return nbd_send_generic_reply(client, request->handle, ret,
--
2.21.0
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