From 072f9ac44aac54ee9ac006e8b42841abfde48a8b Mon Sep 17 00:00:00 2001 From: Chrysostomos Nanakos Date: Tue, 2 Sep 2014 15:41:34 +0300 Subject: [PATCH] block/archipelago: Use QEMU atomic builtins Replace __sync builtins with ones provided by QEMU for atomic operations. Special thanks goes to Paolo Bonzini for his refactoring suggestion in order to use the already existing atomic builtins interface. Signed-off-by: Chrysostomos Nanakos Signed-off-by: Stefan Hajnoczi --- block/archipelago.c | 76 ++++++++++++++------------------------------- 1 file changed, 23 insertions(+), 53 deletions(-) diff --git a/block/archipelago.c b/block/archipelago.c index 34f72dc5a5..22a7daaa41 100644 --- a/block/archipelago.c +++ b/block/archipelago.c @@ -57,6 +57,7 @@ #include "qapi/qmp/qint.h" #include "qapi/qmp/qstring.h" #include "qapi/qmp/qjson.h" +#include "qemu/atomic.h" #include #include @@ -214,7 +215,7 @@ static void xseg_request_handler(void *state) xseg_put_request(s->xseg, req, s->srcport); - if ((__sync_add_and_fetch(&segreq->ref, -1)) == 0) { + if (atomic_fetch_dec(&segreq->ref) == 1) { if (!segreq->failed) { reqdata->aio_cb->ret = segreq->count; archipelago_finish_aiocb(reqdata); @@ -233,7 +234,7 @@ static void xseg_request_handler(void *state) segreq->count += req->serviced; xseg_put_request(s->xseg, req, s->srcport); - if ((__sync_add_and_fetch(&segreq->ref, -1)) == 0) { + if (atomic_fetch_dec(&segreq->ref) == 1) { if (!segreq->failed) { reqdata->aio_cb->ret = segreq->count; archipelago_finish_aiocb(reqdata); @@ -824,78 +825,47 @@ static int archipelago_aio_segmented_rw(BDRVArchipelagoState *s, ArchipelagoAIOCB *aio_cb, int op) { - int i, ret, segments_nr, last_segment_size; + int ret, segments_nr; + size_t pos = 0; ArchipelagoSegmentedRequest *segreq; - segreq = g_new(ArchipelagoSegmentedRequest, 1); + segreq = g_new0(ArchipelagoSegmentedRequest, 1); if (op == ARCHIP_OP_FLUSH) { segments_nr = 1; - segreq->ref = segments_nr; - segreq->total = count; - segreq->count = 0; - segreq->failed = 0; - ret = archipelago_submit_request(s, 0, count, offset, aio_cb, - segreq, ARCHIP_OP_FLUSH); - if (ret < 0) { - goto err_exit; - } - return 0; + } else { + segments_nr = (int)(count / MAX_REQUEST_SIZE) + \ + ((count % MAX_REQUEST_SIZE) ? 1 : 0); } - - segments_nr = (int)(count / MAX_REQUEST_SIZE) + \ - ((count % MAX_REQUEST_SIZE) ? 1 : 0); - last_segment_size = (int)(count % MAX_REQUEST_SIZE); - - segreq->ref = segments_nr; segreq->total = count; - segreq->count = 0; - segreq->failed = 0; + atomic_mb_set(&segreq->ref, segments_nr); - for (i = 0; i < segments_nr - 1; i++) { - ret = archipelago_submit_request(s, i * MAX_REQUEST_SIZE, - MAX_REQUEST_SIZE, - offset + i * MAX_REQUEST_SIZE, - aio_cb, segreq, op); + while (segments_nr > 1) { + ret = archipelago_submit_request(s, pos, + MAX_REQUEST_SIZE, + offset + pos, + aio_cb, segreq, op); if (ret < 0) { goto err_exit; } + count -= MAX_REQUEST_SIZE; + pos += MAX_REQUEST_SIZE; + segments_nr--; } - - if ((segments_nr > 1) && last_segment_size) { - ret = archipelago_submit_request(s, i * MAX_REQUEST_SIZE, - last_segment_size, - offset + i * MAX_REQUEST_SIZE, - aio_cb, segreq, op); - } else if ((segments_nr > 1) && !last_segment_size) { - ret = archipelago_submit_request(s, i * MAX_REQUEST_SIZE, - MAX_REQUEST_SIZE, - offset + i * MAX_REQUEST_SIZE, - aio_cb, segreq, op); - } else if (segments_nr == 1) { - ret = archipelago_submit_request(s, 0, count, offset, aio_cb, - segreq, op); - } + ret = archipelago_submit_request(s, pos, count, offset + pos, + aio_cb, segreq, op); if (ret < 0) { goto err_exit; } - return 0; err_exit: - __sync_add_and_fetch(&segreq->failed, 1); - if (segments_nr == 1) { - if (__sync_add_and_fetch(&segreq->ref, -1) == 0) { - g_free(segreq); - } - } else { - if ((__sync_add_and_fetch(&segreq->ref, -segments_nr + i)) == 0) { - g_free(segreq); - } + segreq->failed = 1; + if (atomic_fetch_sub(&segreq->ref, segments_nr) == segments_nr) { + g_free(segreq); } - return ret; }