[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer i
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev |
Date: |
Wed, 22 Feb 2017 13:47:10 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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 <address@hidden>
> > >> ---
> > >> 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 <address@hidden>
You gave R-b for both patches, but did not merge it - who is supposed to
do that?
Kevin
[Qemu-devel] [PATCH 1/2] block/nfs: convert to preadv / pwritev, Peter Lieven, 2017/02/17
Re: [Qemu-devel] [PATCH 0/2] block/nfs optimizations, Jeff Cody, 2017/02/23