From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XFo9J-0003d5-0c for qemu-devel@nongnu.org; Fri, 08 Aug 2014 13:40:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XFo9C-0006UT-Ql for qemu-devel@nongnu.org; Fri, 08 Aug 2014 13:40:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46310) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XFo9C-0006UJ-ID for qemu-devel@nongnu.org; Fri, 08 Aug 2014 13:40:10 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s78He9Ra001455 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Fri, 8 Aug 2014 13:40:09 -0400 From: Kevin Wolf Date: Fri, 8 Aug 2014 19:39:02 +0200 Message-Id: <1407519603-6635-2-git-send-email-kwolf@redhat.com> In-Reply-To: <1407519603-6635-1-git-send-email-kwolf@redhat.com> References: <1407519603-6635-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 01/62] nbd: Drop nbd_can_read() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com From: Max Reitz There is no variant of aio_set_fd_handler() like qemu_set_fd_handler2(), so we cannot give a can_read() callback function. Instead, unregister the nbd_read() function whenever we cannot read and re-register it as soon as we can read again. All this is hidden behind the functions nbd_set_handlers() (which registers all handlers for the AIO context and file descriptor belonging to the given client), nbd_unset_handlers() (which unregisters them) and nbd_update_can_read() (which checks whether NBD can read for the given client and acts accordingly). Signed-off-by: Max Reitz Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- nbd.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 53 insertions(+), 19 deletions(-) diff --git a/nbd.c b/nbd.c index e7d1cee..210b6d5 100644 --- a/nbd.c +++ b/nbd.c @@ -18,6 +18,7 @@ #include "block/nbd.h" #include "block/block.h" +#include "block/block_int.h" #include "block/coroutine.h" @@ -107,6 +108,8 @@ struct NBDExport { uint32_t nbdflags; QTAILQ_HEAD(, NBDClient) clients; QTAILQ_ENTRY(NBDExport) next; + + AioContext *ctx; }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); @@ -123,6 +126,8 @@ struct NBDClient { CoMutex send_lock; Coroutine *send_coroutine; + bool can_read; + QTAILQ_ENTRY(NBDClient) next; int nb_requests; bool closing; @@ -130,6 +135,10 @@ struct NBDClient { /* That's all folks */ +static void nbd_set_handlers(NBDClient *client); +static void nbd_unset_handlers(NBDClient *client); +static void nbd_update_can_read(NBDClient *client); + ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read) { size_t offset = 0; @@ -862,7 +871,7 @@ void nbd_client_put(NBDClient *client) */ assert(client->closing); - qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL); + nbd_unset_handlers(client); close(client->sock); client->sock = -1; if (client->exp) { @@ -898,6 +907,7 @@ static NBDRequest *nbd_request_get(NBDClient *client) assert(client->nb_requests <= MAX_NBD_REQUESTS - 1); client->nb_requests++; + nbd_update_can_read(client); req = g_slice_new0(NBDRequest); nbd_client_get(client); @@ -914,9 +924,8 @@ static void nbd_request_put(NBDRequest *req) } g_slice_free(NBDRequest, req); - if (client->nb_requests-- == MAX_NBD_REQUESTS) { - qemu_notify_event(); - } + client->nb_requests--; + nbd_update_can_read(client); nbd_client_put(client); } @@ -932,6 +941,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, exp->nbdflags = nbdflags; exp->size = size == -1 ? bdrv_getlength(bs) : size; exp->close = close; + exp->ctx = bdrv_get_aio_context(bs); bdrv_ref(bs); return exp; } @@ -1023,10 +1033,6 @@ void nbd_export_close_all(void) } } -static int nbd_can_read(void *opaque); -static void nbd_read(void *opaque); -static void nbd_restart_write(void *opaque); - static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply, int len) { @@ -1035,9 +1041,8 @@ static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply, ssize_t rc, ret; qemu_co_mutex_lock(&client->send_lock); - qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, - nbd_restart_write, client); client->send_coroutine = qemu_coroutine_self(); + nbd_set_handlers(client); if (!len) { rc = nbd_send_reply(csock, reply); @@ -1054,7 +1059,7 @@ static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply, } client->send_coroutine = NULL; - qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client); + nbd_set_handlers(client); qemu_co_mutex_unlock(&client->send_lock); return rc; } @@ -1067,6 +1072,8 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque ssize_t rc; client->recv_coroutine = qemu_coroutine_self(); + nbd_update_can_read(client); + rc = nbd_receive_request(csock, request); if (rc < 0) { if (rc != -EAGAIN) { @@ -1108,6 +1115,8 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque out: client->recv_coroutine = NULL; + nbd_update_can_read(client); + return rc; } @@ -1259,13 +1268,6 @@ out: nbd_client_close(client); } -static int nbd_can_read(void *opaque) -{ - NBDClient *client = opaque; - - return client->recv_coroutine || client->nb_requests < MAX_NBD_REQUESTS; -} - static void nbd_read(void *opaque) { NBDClient *client = opaque; @@ -1284,6 +1286,37 @@ static void nbd_restart_write(void *opaque) qemu_coroutine_enter(client->send_coroutine, NULL); } +static void nbd_set_handlers(NBDClient *client) +{ + if (client->exp && client->exp->ctx) { + aio_set_fd_handler(client->exp->ctx, client->sock, + client->can_read ? nbd_read : NULL, + client->send_coroutine ? nbd_restart_write : NULL, + client); + } +} + +static void nbd_unset_handlers(NBDClient *client) +{ + if (client->exp && client->exp->ctx) { + aio_set_fd_handler(client->exp->ctx, client->sock, NULL, NULL, NULL); + } +} + +static void nbd_update_can_read(NBDClient *client) +{ + bool can_read = client->recv_coroutine || + client->nb_requests < MAX_NBD_REQUESTS; + + if (can_read != client->can_read) { + client->can_read = can_read; + nbd_set_handlers(client); + + /* There is no need to invoke aio_notify(), since aio_set_fd_handler() + * in nbd_set_handlers() will have taken care of that */ + } +} + NBDClient *nbd_client_new(NBDExport *exp, int csock, void (*close)(NBDClient *)) { @@ -1292,13 +1325,14 @@ NBDClient *nbd_client_new(NBDExport *exp, int csock, client->refcount = 1; client->exp = exp; client->sock = csock; + client->can_read = true; if (nbd_send_negotiate(client)) { g_free(client); return NULL; } client->close = close; qemu_co_mutex_init(&client->send_lock); - qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client); + nbd_set_handlers(client); if (exp) { QTAILQ_INSERT_TAIL(&exp->clients, client, next); -- 1.8.3.1