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Date: Wed, 10 Dec 2014 12:21:52 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
David Vrabel <david.vrabel@...rix.com>,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
Andrew Jones <drjones@...hat.com>
Subject: Re: [PATCH v2] xen/blkfront: remove redundant flush_op
On Tue, Dec 09, 2014 at 03:56:46PM -0500, Boris Ostrovsky wrote:
> 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 <vkuznets@...hat.com>
>
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Thank you.
I am testing this and the xen/blkfront: improve protection against issuing unsupported REQ_FUA
right now for 3.19
>
>
> >---
> >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,
>
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