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Wed, 18 Dec 2019 16:51:16 +0000 (UTC) Date: Wed, 18 Dec 2019 17:51:15 +0100 From: Kevin Wolf To: Paolo Bonzini Subject: Re: [PATCH 1/3] block: eliminate BDRV_REQ_NO_SERIALISING Message-ID: <20191218165115.GE4632@linux.fritz.box> References: <1576675026-25046-1-git-send-email-pbonzini@redhat.com> <1576675026-25046-2-git-send-email-pbonzini@redhat.com> <20191218163636.GC4632@linux.fritz.box> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: 0NaomYnLPbGd-BT5r7rQmw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Lieven , qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 18.12.2019 um 17:43 hat Paolo Bonzini geschrieben: > On 18/12/19 17:37, Kevin Wolf wrote: > >> * passthrough flags. */ > >> - assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_REA= D | > >> - BDRV_REQ_PREFETCH))); > >> + assert(!(flags & ~(BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH))); > >> =20 > >> /* Handle Copy on Read and associated serialisation */ > >> if (flags & BDRV_REQ_COPY_ON_READ) { > >> @@ -1458,12 +1457,7 @@ static int coroutine_fn bdrv_aligned_preadv(Bdr= vChild *child, > >> bdrv_mark_request_serialising(req, bdrv_get_cluster_size(bs))= ; > >> } > >> =20 > >> - /* BDRV_REQ_SERIALISING is only for write operation */ > >> - assert(!(flags & BDRV_REQ_SERIALISING)); > > I think we shoud still keep this assertion as long as read requests > > don't mark themselves as serialising when BDRV_REQ_SERIALISING is given= . > > Otherwise, someone might add the flag to a read request and will later > > be surprised that it didn't work. >=20 > I'm removing it because it's anyway tested by the earlier >=20 > assert(!(flags & ~(BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH))); Ah, right. Never mind then. Kevin