Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752588AbaLIUzF (ORCPT ); Tue, 9 Dec 2014 15:55:05 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:30639 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751570AbaLIUzD (ORCPT ); Tue, 9 Dec 2014 15:55:03 -0500 Message-ID: <5487620E.8060807@oracle.com> Date: Tue, 09 Dec 2014 15:56:46 -0500 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Vitaly Kuznetsov CC: Konrad Rzeszutek Wilk , David Vrabel , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Andrew Jones Subject: Re: [PATCH v2] xen/blkfront: remove redundant flush_op References: <54860EA4.7090705@oracle.com> <1418135110-7194-1-git-send-email-vkuznets@redhat.com> In-Reply-To: <1418135110-7194-1-git-send-email-vkuznets@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/09/2014 09:25 AM, Vitaly Kuznetsov wrote: > flush_op is unambiguously defined by feature_flush: > REQ_FUA | REQ_FLUSH -> BLKIF_OP_WRITE_BARRIER > REQ_FLUSH -> BLKIF_OP_FLUSH_DISKCACHE > 0 -> 0 > and thus can be removed. This is just a cleanup. > > The patch was suggested by Boris Ostrovsky. > > Signed-off-by: Vitaly Kuznetsov Reviewed-by: Boris Ostrovsky > --- > Changes from v1: > Future-proof feature_flush against new flags [Boris Ostrovsky]. > > The patch is supposed to be applied after "xen/blkfront: improve protection > against issuing unsupported REQ_FUA". > --- > drivers/block/xen-blkfront.c | 51 +++++++++++++++++++++++++++----------------- > 1 file changed, 31 insertions(+), 20 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 2e6c103..2236c6f 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -126,7 +126,6 @@ struct blkfront_info > unsigned int persistent_gnts_c; > unsigned long shadow_free; > unsigned int feature_flush; > - unsigned int flush_op; > unsigned int feature_discard:1; > unsigned int feature_secdiscard:1; > unsigned int discard_granularity; > @@ -479,7 +478,19 @@ static int blkif_queue_request(struct request *req) > * way. (It's also a FLUSH+FUA, since it is > * guaranteed ordered WRT previous writes.) > */ > - ring_req->operation = info->flush_op; > + switch (info->feature_flush & > + ((REQ_FLUSH|REQ_FUA))) { > + case REQ_FLUSH|REQ_FUA: > + ring_req->operation = > + BLKIF_OP_WRITE_BARRIER; > + break; > + case REQ_FLUSH: > + ring_req->operation = > + BLKIF_OP_FLUSH_DISKCACHE; > + break; > + default: > + ring_req->operation = 0; > + } > } > ring_req->u.rw.nr_segments = nseg; > } > @@ -685,20 +696,26 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, > return 0; > } > > +static const char *flush_info(unsigned int feature_flush) > +{ > + switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) { > + case REQ_FLUSH|REQ_FUA: > + return "barrier: enabled;"; > + case REQ_FLUSH: > + return "flush diskcache: enabled;"; > + default: > + return "barrier or flush: disabled;"; > + } > +} > > static void xlvbd_flush(struct blkfront_info *info) > { > blk_queue_flush(info->rq, info->feature_flush); > - printk(KERN_INFO "blkfront: %s: %s: %s %s %s %s %s\n", > - info->gd->disk_name, > - info->flush_op == BLKIF_OP_WRITE_BARRIER ? > - "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? > - "flush diskcache" : "barrier or flush"), > - info->feature_flush ? "enabled;" : "disabled;", > - "persistent grants:", > - info->feature_persistent ? "enabled;" : "disabled;", > - "indirect descriptors:", > - info->max_indirect_segments ? "enabled;" : "disabled;"); > + pr_info("blkfront: %s: %s %s %s %s %s\n", > + info->gd->disk_name, flush_info(info->feature_flush), > + "persistent grants:", info->feature_persistent ? > + "enabled;" : "disabled;", "indirect descriptors:", > + info->max_indirect_segments ? "enabled;" : "disabled;"); > } > > static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) > @@ -1190,7 +1207,6 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) > if (error == -EOPNOTSUPP) > error = 0; > info->feature_flush = 0; > - info->flush_op = 0; > xlvbd_flush(info); > } > /* fall through */ > @@ -1810,7 +1826,6 @@ static void blkfront_connect(struct blkfront_info *info) > physical_sector_size = sector_size; > > info->feature_flush = 0; > - info->flush_op = 0; > > err = xenbus_gather(XBT_NIL, info->xbdev->otherend, > "feature-barrier", "%d", &barrier, > @@ -1823,10 +1838,8 @@ static void blkfront_connect(struct blkfront_info *info) > * > * If there are barriers, then we use flush. > */ > - if (!err && barrier) { > + if (!err && barrier) > info->feature_flush = REQ_FLUSH | REQ_FUA; > - info->flush_op = BLKIF_OP_WRITE_BARRIER; > - } > /* > * And if there is "feature-flush-cache" use that above > * barriers. > @@ -1835,10 +1848,8 @@ static void blkfront_connect(struct blkfront_info *info) > "feature-flush-cache", "%d", &flush, > NULL); > > - if (!err && flush) { > + if (!err && flush) > info->feature_flush = REQ_FLUSH; > - info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; > - } > > err = xenbus_gather(XBT_NIL, info->xbdev->otherend, > "feature-discard", "%d", &discard, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/