From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45706) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1atkht-0004QB-6M for qemu-devel@nongnu.org; Fri, 22 Apr 2016 19:41:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1atkhs-0005i5-4S for qemu-devel@nongnu.org; Fri, 22 Apr 2016 19:41:53 -0400 From: Eric Blake Date: Fri, 22 Apr 2016 17:40:49 -0600 Message-Id: <1461368452-10389-42-git-send-email-eblake@redhat.com> In-Reply-To: <1461368452-10389-1-git-send-email-eblake@redhat.com> References: <1461368452-10389-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v3 41/44] nbd: Implement NBD_CMD_WRITE_ZEROES on server List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, alex@alex.org.uk, Paolo Bonzini , Kevin Wolf , Max Reitz Upstream NBD protocol recently added the ability to efficiently write zeroes without having to send the zeroes over the wire, along with a flag to control whether the client wants a hole. Signed-off-by: Eric Blake --- v3: abandon NBD_CMD_CLOSE extension, rebase to use blk_pwrite_zeroes --- include/block/nbd.h | 7 +++++-- nbd/server.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 45 insertions(+), 4 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index 05c0e48..1072d9e 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -70,6 +70,7 @@ typedef struct nbd_reply nbd_reply; #define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */ #define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - rotational media */ #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ +#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */ /* New-style handshake (global) flags, sent from server to client, and control what will happen during handshake phase. */ @@ -102,7 +103,8 @@ typedef struct nbd_reply nbd_reply; #define NBD_INFO_DESCRIPTION 2 /* Request flags, sent from client to server during transmission phase */ -#define NBD_CMD_FLAG_FUA (1 << 0) +#define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */ +#define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */ /* Supported request types */ enum { @@ -110,7 +112,8 @@ enum { NBD_CMD_WRITE = 1, NBD_CMD_DISC = 2, NBD_CMD_FLUSH = 3, - NBD_CMD_TRIM = 4 + NBD_CMD_TRIM = 4, + NBD_CMD_WRITE_ZEROES = 5, }; #define NBD_DEFAULT_PORT 10809 diff --git a/nbd/server.c b/nbd/server.c index 1edb5f3..563afb2 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -689,7 +689,8 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data) char buf[8 + 8 + 8 + 128]; int rc; const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM | - NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA); + NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA | + NBD_FLAG_SEND_WRITE_ZEROES); bool oldStyle; size_t len; @@ -1199,11 +1200,17 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, rc = -EINVAL; goto out; } - if (request->flags & ~NBD_CMD_FLAG_FUA) { + if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) { LOG("unsupported flags (got 0x%x)", request->flags); rc = -EINVAL; goto out; } + if (request->type != NBD_CMD_WRITE_ZEROES && + (request->flags & NBD_CMD_FLAG_NO_HOLE)) { + LOG("unexpected flags (got 0x%x)", request->flags); + rc = -EINVAL; + goto out; + } rc = 0; @@ -1308,6 +1315,37 @@ static void nbd_trip(void *opaque) } break; + case NBD_CMD_WRITE_ZEROES: + TRACE("Request type is WRITE_ZEROES"); + + if (exp->nbdflags & NBD_FLAG_READ_ONLY) { + TRACE("Server is read-only, return error"); + reply.error = EROFS; + goto error_reply; + } + + TRACE("Writing to device"); + + flags = 0; + if (request.flags & NBD_CMD_FLAG_FUA) { + flags |= BDRV_REQ_FUA; + } + if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) { + flags |= BDRV_REQ_MAY_UNMAP; + } + ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset, + request.len, flags); + if (ret < 0) { + LOG("writing to file failed"); + reply.error = -ret; + goto error_reply; + } + + if (nbd_co_send_reply(req, &reply, 0) < 0) { + goto out; + } + break; + case NBD_CMD_DISC: /* unreachable, thanks to special case in nbd_co_receive_request() */ abort(); -- 2.5.5