Commit b491dbb7 authored by Eric Blake's avatar Eric Blake
Browse files

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: default avatarEric Blake <eblake@redhat.com>
Message-Id: <20190823143726.27062-5-eblake@redhat.com>
Reviewed-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: update iotests 223, 233]
parent f061656c

nbd/server.c

+6 −2
Original line number Diff line number Diff line
@@ -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,

tests/qemu-iotests/223.out

+1 −1
Original line number Diff line number Diff line
@@ -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

tests/qemu-iotests/233.out

+1 −1
Original line number Diff line number Diff line
@@ -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