On 15/07/2016 20:32, Eric Blake wrote: > Now that the block layer will honor max_transfer, we can simplify > our code to rely on that guarantee. > > The readv code can call directly into nbd-client, just as the > writev code has done since commit 52a4650. > > Interestingly enough, while qemu-io 'w 0 40m' splits into a 32M > and 8M transaction, 'w -z 0 40m' splits into two 16M and an 8M, > because the block layer caps the bounce buffer for writing zeroes > at 16M. When we later introduce support for NBD_CMD_WRITE_ZEROES, > we can get a full 32M zero write (or larger, if the client and > server negotiate that write zeroes can use a larger size than > ordinary writes). > > Signed-off-by: Eric Blake <ebl...@redhat.com> > Reviewed-by: Fam Zheng <f...@redhat.com> > Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> > --- > block/nbd-client.c | 51 ++++++++------------------------------------------- > block/nbd.c | 12 +++--------- > 2 files changed, 11 insertions(+), 52 deletions(-) > > diff --git a/block/nbd-client.c b/block/nbd-client.c > index 4cc408d..f1fb58b 100644 > --- a/block/nbd-client.c > +++ b/block/nbd-client.c > @@ -217,15 +217,15 @@ static void nbd_coroutine_end(NbdClientSession *s, > } > } > > -static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num, > - int nb_sectors, QEMUIOVector *qiov, > - int offset) > +int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors, QEMUIOVector *qiov) > { > NbdClientSession *client = nbd_get_client_session(bs); > struct nbd_request request = { .type = NBD_CMD_READ }; > struct nbd_reply reply; > ssize_t ret; > > + assert(nb_sectors <= NBD_MAX_SECTORS); > request.from = sector_num * 512; > request.len = nb_sectors * 512; > > @@ -234,16 +234,15 @@ static int nbd_co_readv_1(BlockDriverState *bs, int64_t > sector_num, > if (ret < 0) { > reply.error = -ret; > } else { > - nbd_co_receive_reply(client, &request, &reply, qiov, offset); > + nbd_co_receive_reply(client, &request, &reply, qiov, 0); > } > nbd_coroutine_end(client, &request); > return -reply.error; > > } > > -static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, > - int nb_sectors, QEMUIOVector *qiov, > - int offset, int flags) > +int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors, QEMUIOVector *qiov, int flags) > { > NbdClientSession *client = nbd_get_client_session(bs); > struct nbd_request request = { .type = NBD_CMD_WRITE }; > @@ -255,11 +254,12 @@ static int nbd_co_writev_1(BlockDriverState *bs, > int64_t sector_num, > request.type |= NBD_CMD_FLAG_FUA; > } > > + assert(nb_sectors <= NBD_MAX_SECTORS); > request.from = sector_num * 512; > request.len = nb_sectors * 512; > > nbd_coroutine_start(client, &request); > - ret = nbd_co_send_request(bs, &request, qiov, offset); > + ret = nbd_co_send_request(bs, &request, qiov, 0); > if (ret < 0) { > reply.error = -ret; > } else { > @@ -269,41 +269,6 @@ static int nbd_co_writev_1(BlockDriverState *bs, int64_t > sector_num, > return -reply.error; > } > > -int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, > - int nb_sectors, QEMUIOVector *qiov) > -{ > - int offset = 0; > - int ret; > - while (nb_sectors > NBD_MAX_SECTORS) { > - ret = nbd_co_readv_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset); > - if (ret < 0) { > - return ret; > - } > - offset += NBD_MAX_SECTORS * 512; > - sector_num += NBD_MAX_SECTORS; > - nb_sectors -= NBD_MAX_SECTORS; > - } > - return nbd_co_readv_1(bs, sector_num, nb_sectors, qiov, offset); > -} > - > -int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, > - int nb_sectors, QEMUIOVector *qiov, int flags) > -{ > - int offset = 0; > - int ret; > - while (nb_sectors > NBD_MAX_SECTORS) { > - ret = nbd_co_writev_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset, > - flags); > - if (ret < 0) { > - return ret; > - } > - offset += NBD_MAX_SECTORS * 512; > - sector_num += NBD_MAX_SECTORS; > - nb_sectors -= NBD_MAX_SECTORS; > - } > - return nbd_co_writev_1(bs, sector_num, nb_sectors, qiov, offset, flags); > -} > - > int nbd_client_co_flush(BlockDriverState *bs) > { > NbdClientSession *client = nbd_get_client_session(bs); > diff --git a/block/nbd.c b/block/nbd.c > index 08e5b67..8a13078 100644 > --- a/block/nbd.c > +++ b/block/nbd.c > @@ -349,12 +349,6 @@ static int nbd_open(BlockDriverState *bs, QDict > *options, int flags, > return ret; > } > > -static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num, > - int nb_sectors, QEMUIOVector *qiov) > -{ > - return nbd_client_co_readv(bs, sector_num, nb_sectors, qiov); > -} > - > static int nbd_co_flush(BlockDriverState *bs) > { > return nbd_client_co_flush(bs); > @@ -450,7 +444,7 @@ static BlockDriver bdrv_nbd = { > .instance_size = sizeof(BDRVNBDState), > .bdrv_parse_filename = nbd_parse_filename, > .bdrv_file_open = nbd_open, > - .bdrv_co_readv = nbd_co_readv, > + .bdrv_co_readv = nbd_client_co_readv, > .bdrv_co_writev_flags = nbd_client_co_writev, > .bdrv_close = nbd_close, > .bdrv_co_flush_to_os = nbd_co_flush, > @@ -468,7 +462,7 @@ static BlockDriver bdrv_nbd_tcp = { > .instance_size = sizeof(BDRVNBDState), > .bdrv_parse_filename = nbd_parse_filename, > .bdrv_file_open = nbd_open, > - .bdrv_co_readv = nbd_co_readv, > + .bdrv_co_readv = nbd_client_co_readv, > .bdrv_co_writev_flags = nbd_client_co_writev, > .bdrv_close = nbd_close, > .bdrv_co_flush_to_os = nbd_co_flush, > @@ -486,7 +480,7 @@ static BlockDriver bdrv_nbd_unix = { > .instance_size = sizeof(BDRVNBDState), > .bdrv_parse_filename = nbd_parse_filename, > .bdrv_file_open = nbd_open, > - .bdrv_co_readv = nbd_co_readv, > + .bdrv_co_readv = nbd_client_co_readv, > .bdrv_co_writev_flags = nbd_client_co_writev, > .bdrv_close = nbd_close, > .bdrv_co_flush_to_os = nbd_co_flush, >
Acked-by: Paolo Bonzini <pbonz...@redhat.com>