From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:39985) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SVO1B-0003jt-Vb for qemu-devel@nongnu.org; Fri, 18 May 2012 10:19:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SVO13-0005wN-BY for qemu-devel@nongnu.org; Fri, 18 May 2012 10:18:57 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:52105) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SVO13-0005wH-2r for qemu-devel@nongnu.org; Fri, 18 May 2012 10:18:49 -0400 Received: by pbbro12 with SMTP id ro12so4994600pbb.4 for ; Fri, 18 May 2012 07:18:47 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 18 May 2012 16:18:26 +0200 Message-Id: <1337350712-29183-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1337350712-29183-1-git-send-email-pbonzini@redhat.com> References: <1337350712-29183-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [RFC PATCH 1/7] block: flush in writethrough mode after writes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@linux.vnet.ibm.com, anthony@codemonkey.ws We want to make the formats handle their own flushes autonomously, while keeping for guests the ability to use a writethrough cache. Since formats will write metadata via bs->file, bdrv_co_do_writev is the only place where we need to add a flush. Signed-off-by: Paolo Bonzini --- block.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index af2ab4f..7add33c 100644 --- a/block.c +++ b/block.c @@ -1747,8 +1747,8 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, return ret; } - /* No flush needed for cache modes that use O_DSYNC */ - if ((bs->open_flags & BDRV_O_CACHE_WB) != 0) { + /* No flush needed for cache modes that already do it */ + if (bs->enable_write_cache) { bdrv_flush(bs); } @@ -1797,6 +1797,9 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs, ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num, cluster_nb_sectors); } else { + /* This does not change the data on the disk, it is not necessary + * to flush even in cache=writethrough mode. + */ ret = drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, &bounce_qiov); } @@ -1966,6 +1969,10 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov); } + if (ret == 0 && !bs->enable_write_cache) { + ret = bdrv_co_flush(bs); + } + if (bs->dirty_bitmap) { set_dirty_bitmap(bs, sector_num, nb_sectors, 1); } -- 1.7.10.1