From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:33250) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBLjw-0007cH-94 for qemu-devel@nongnu.org; Wed, 05 Oct 2011 03:18:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RBLju-0006Hm-FE for qemu-devel@nongnu.org; Wed, 05 Oct 2011 03:18:04 -0400 Received: from mail-ww0-f53.google.com ([74.125.82.53]:42322) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBLju-0006EG-49 for qemu-devel@nongnu.org; Wed, 05 Oct 2011 03:18:02 -0400 Received: by mail-ww0-f53.google.com with SMTP id 14so1759680wwg.10 for ; Wed, 05 Oct 2011 00:18:01 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 5 Oct 2011 09:17:44 +0200 Message-Id: <1317799065-29668-15-git-send-email-pbonzini@redhat.com> In-Reply-To: <1317799065-29668-1-git-send-email-pbonzini@redhat.com> References: <1317799065-29668-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH v3 14/15] nbd: split requests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org qemu-nbd has a limit of slightly less than 1M per request. Work around this in the nbd block driver. Signed-off-by: Paolo Bonzini --- block/nbd.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 46 insertions(+), 6 deletions(-) diff --git a/block/nbd.c b/block/nbd.c index 90c4f2f..a52b6f2 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -277,8 +277,9 @@ static int nbd_open(BlockDriverState *bs, const char* filename, int flags) return result; } -static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) +static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov, + int offset) { BDRVNBDState *s = bs->opaque; struct nbd_request request; @@ -292,15 +293,16 @@ static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num, if (nbd_co_send_request(s, &request, NULL, 0) == -1) { reply.error = errno; } else { - nbd_co_receive_reply(s, &request, &reply, qiov->iov, 0); + nbd_co_receive_reply(s, &request, &reply, qiov->iov, offset); } nbd_coroutine_end(s, &request); return -reply.error; } -static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) +static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov, + int offset) { BDRVNBDState *s = bs->opaque; struct nbd_request request; @@ -315,7 +317,7 @@ static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num, request.len = nb_sectors * 512; nbd_coroutine_start(s, &request); - if (nbd_co_send_request(s, &request, qiov->iov, 0) == -1) { + if (nbd_co_send_request(s, &request, qiov->iov, offset) == -1) { reply.error = errno; } else { nbd_co_receive_reply(s, &request, &reply, NULL, 0); @@ -324,6 +326,44 @@ static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num, return -reply.error; } +/* qemu-nbd has a limit of slightly less than 1M per request. Try to + * remain aligned to 4K. */ +#define NBD_MAX_SECTORS 2040 + +static int nbd_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); +} + +static int nbd_co_writev(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_writev_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_writev_1(bs, sector_num, nb_sectors, qiov, offset); +} + static int nbd_co_flush(BlockDriverState *bs) { BDRVNBDState *s = bs->opaque; -- 1.7.6