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Date: Tue, 9 Dec 2014 15:25:10 +0100
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
David Vrabel <david.vrabel@...rix.com>,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
Andrew Jones <drjones@...hat.com>
Subject: [PATCH v2] xen/blkfront: remove redundant flush_op
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>
---
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,
--
1.9.3
--
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