From f834b08ab5b70b9a39bb0b6c351a65ad46b5879f Mon Sep 17 00:00:00 2001 From: John Snow Date: Wed, 18 Jul 2018 22:55:06 +0200 Subject: [PATCH 81/89] nbd/server: introduce NBD_CMD_CACHE RH-Author: John Snow Message-id: <20180718225511.14878-31-jsnow@redhat.com> Patchwork-id: 81419 O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 30/35] nbd/server: introduce NBD_CMD_CACHE Bugzilla: 1207657 RH-Acked-by: Eric Blake RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Fam Zheng From: Vladimir Sementsov-Ogievskiy 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 Message-Id: <20180413143156.11409-1-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake [eblake: fix two missing case labels in switch statements] Signed-off-by: Eric Blake (cherry picked from commit bc37b06a5cde24fb24c2a2cc44dd86756034ba9d) Signed-off-by: John Snow Signed-off-by: Miroslav Rezanina --- include/block/nbd.h | 3 ++- nbd/common.c | 2 ++ nbd/server.c | 11 +++++++---- 3 files changed, 11 insertions(+), 5 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index 8bb9606..daaeae6 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/common.c b/nbd/common.c index 8c95c1d..41f5ed8 100644 --- a/nbd/common.c +++ b/nbd/common.c @@ -148,6 +148,8 @@ const char *nbd_cmd_lookup(uint16_t cmd) return "flush"; case NBD_CMD_TRIM: return "trim"; + case NBD_CMD_CACHE: + return "cache"; case NBD_CMD_WRITE_ZEROES: return "write zeroes"; case NBD_CMD_BLOCK_STATUS: diff --git a/nbd/server.c b/nbd/server.c index 2c2d62c..2746046 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1252,7 +1252,7 @@ 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 @@ -2034,7 +2034,9 @@ 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); @@ -2119,7 +2121,7 @@ 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) { @@ -2138,7 +2140,7 @@ 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); } @@ -2171,6 +2173,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, switch (request->type) { case NBD_CMD_READ: + case NBD_CMD_CACHE: return nbd_do_cmd_read(client, request, data, errp); case NBD_CMD_WRITE: -- 1.8.3.1