From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43999) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cgWKG-00034N-6p for qemu-devel@nongnu.org; Wed, 22 Feb 2017 07:47:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cgWKF-0003OH-Ce for qemu-devel@nongnu.org; Wed, 22 Feb 2017 07:47:20 -0500 Date: Wed, 22 Feb 2017 13:47:10 +0100 From: Kevin Wolf Message-ID: <20170222124710.GL4112@noname.str.redhat.com> References: <1487349541-10201-1-git-send-email-pl@kamp.de> <1487349541-10201-3-git-send-email-pl@kamp.de> <20170217213715.GJ19045@localhost.localdomain> <20170217215117.GM19045@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170217215117.GM19045@localhost.localdomain> Subject: Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jeff Cody Cc: Eric Blake , Peter Lieven , qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Am 17.02.2017 um 22:51 hat Jeff Cody geschrieben: > On Fri, Feb 17, 2017 at 03:42:52PM -0600, Eric Blake wrote: > > On 02/17/2017 03:37 PM, Jeff Cody wrote: > > > On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: > > >> if the passed qiov contains exactly one iov we can > > >> pass the buffer directly. > > >> > > >> Signed-off-by: Peter Lieven > > >> --- > > >> block/nfs.c | 23 ++++++++++++++++------- > > >> 1 file changed, 16 insertions(+), 7 deletions(-) > > >> > > >> diff --git a/block/nfs.c b/block/nfs.c > > >> index ab5dcc2..bb4b75f 100644 > > >> --- a/block/nfs.c > > >> +++ b/block/nfs.c > > >> @@ -295,20 +295,27 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, > > >> NFSClient *client = bs->opaque; > > >> NFSRPC task; > > >> char *buf = NULL; > > >> + bool my_buffer = false; > > > > > > g_free() is a nop if buf is NULL, so there is no need for the my_buffer > > > variable & check. > > > > Umm, yes there is: > > > > >> + if (iov->niov != 1) { > > >> + buf = g_try_malloc(bytes); > > >> + if (bytes && buf == NULL) { > > >> + return -ENOMEM; > > >> + } > > >> + qemu_iovec_to_buf(iov, 0, buf, bytes); > > >> + my_buffer = true; > > >> + } else { > > >> + buf = iov->iov[0].iov_base; > > > > If we took the else branch, then we definitely do not want to be calling > > g_free(buf). > > Doh! > > > > > >> } > > >> > > >> - qemu_iovec_to_buf(iov, 0, buf, bytes); > > >> - > > >> if (nfs_pwrite_async(client->context, client->fh, > > >> offset, bytes, buf, > > >> nfs_co_generic_cb, &task) != 0) { > > >> - g_free(buf); > > >> + if (my_buffer) { > > >> + g_free(buf); > > >> + } > > > > It looks correct as-is to me. > > Indeed. > > Reviewed-by: Jeff Cody You gave R-b for both patches, but did not merge it - who is supposed to do that? Kevin