From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36309) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f6zkE-00007f-RT for qemu-devel@nongnu.org; Fri, 13 Apr 2018 10:32:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f6zk9-0001g7-RN for qemu-devel@nongnu.org; Fri, 13 Apr 2018 10:32:06 -0400 From: Vladimir Sementsov-Ogievskiy Date: Fri, 13 Apr 2018 17:31:56 +0300 Message-Id: <20180413143156.11409-1-vsementsov@virtuozzo.com> Subject: [Qemu-devel] [PATCH] nbd/server: introduce NBD_CMD_CACHE List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: mreitz@redhat.com, kwolf@redhat.com, den@openvz.org, vsementsov@virtuozzo.com, pbonzini@redhat.com, eblake@redhat.com Handle nbd CACHE command. Just do read, without sending read data back. Cache mechanism should be done by exported node driver chain. Signed-off-by: Vladimir Sementsov-Ogievskiy --- include/block/nbd.h | 3 ++- nbd/server.c | 10 ++++++---- 2 files changed, 8 insertions(+), 5 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index fcdcd54502..b4793d0a29 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -135,6 +135,7 @@ typedef struct NBDExtent { #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */ #define NBD_FLAG_SEND_DF (1 << 7) /* Send DF (Do not Fragment) */ +#define NBD_FLAG_SEND_CACHE (1 << 8) /* Send CACHE (prefetch) */ /* New-style handshake (global) flags, sent from server to client, and control what will happen during handshake phase. */ @@ -195,7 +196,7 @@ enum { NBD_CMD_DISC = 2, NBD_CMD_FLUSH = 3, NBD_CMD_TRIM = 4, - /* 5 reserved for failed experiment NBD_CMD_CACHE */ + NBD_CMD_CACHE = 5, NBD_CMD_WRITE_ZEROES = 6, NBD_CMD_BLOCK_STATUS = 7, }; diff --git a/nbd/server.c b/nbd/server.c index 9e1f227178..30d7d3f444 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1134,7 +1134,7 @@ static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp) int ret; const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA | - NBD_FLAG_SEND_WRITE_ZEROES); + NBD_FLAG_SEND_WRITE_ZEROES | NBD_FLAG_SEND_CACHE); bool oldStyle; /* Old style negotiation header, no room for options @@ -1826,7 +1826,9 @@ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request, return -EIO; } - if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) { + if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE || + request->type == NBD_CMD_CACHE) + { if (request->len > NBD_MAX_BUFFER_SIZE) { error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)", request->len, NBD_MAX_BUFFER_SIZE); @@ -1911,7 +1913,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, int ret; NBDExport *exp = client->exp; - assert(request->type == NBD_CMD_READ); + assert(request->type == NBD_CMD_READ || request->type == NBD_CMD_CACHE); /* XXX: NBD Protocol only documents use of FUA with WRITE */ if (request->flags & NBD_CMD_FLAG_FUA) { @@ -1930,7 +1932,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, ret = blk_pread(exp->blk, request->from + exp->dev_offset, data, request->len); - if (ret < 0) { + if (ret < 0 || request->type == NBD_CMD_CACHE) { return nbd_send_generic_reply(client, request->handle, ret, "reading from file failed", errp); } -- 2.11.1