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nbd: Implement server use of NBD FAST_ZERO 

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 <eblake@redhat.com>
Message-Id: <20190823143726.27062-5-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: update iotests 223, 233]
This commit is contained in:
Eric Blake 2019-08-23 09:37:25 -05:00
parent f061656cc3
commit b491dbb7f8
3 changed files with 8 additions and 4 deletions
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8
nbd/server.c
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@ -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
tests/qemu-iotests/223.out
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@ -49,7 +49,7 @@ exports available: 2
qemu:dirty-bitmap:b
export: 'n2'
size: 4194304
flags: 0x4ed ( flush fua trim zeroes df cache )
flags: 0xced ( flush fua trim zeroes df cache fast-zero )
min block: 1
opt block: 4096
max block: 33554432

2
tests/qemu-iotests/233.out
View File

@ -37,7 +37,7 @@ disk size: unavailable
exports available: 1
export: ''
size: 67108864
flags: 0x4ed ( flush fua trim zeroes df cache )
flags: 0xced ( flush fua trim zeroes df cache fast-zero )
min block: 1
opt block: 4096
max block: 33554432