[PATCH 10/26] xen-blkfront: don't disable cache flushes when they fail

[Christoph Hellwig <hch@lst.de>]

blkfront always had a robust negotiation protocol for detecting a write
cache.  Stop simply disabling cache flushes when they fail as that is
a grave error.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/xen-blkfront.c | 29 +++++++++--------------------
 1 file changed, 9 insertions(+), 20 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9b4ec3e4908cce..9794ac2d3299d1 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -982,18 +982,6 @@ static const char *flush_info(struct blkfront_info *info)
 		return "barrier or flush: disabled;";
 }
 
-static void xlvbd_flush(struct blkfront_info *info)
-{
-	blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
-			      info->feature_fua ? true : false);
-	pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
-		info->gd->disk_name, flush_info(info),
-		"persistent grants:", info->feature_persistent ?
-		"enabled;" : "disabled;", "indirect descriptors:",
-		info->max_indirect_segments ? "enabled;" : "disabled;",
-		"bounce buffer:", info->bounce ? "enabled" : "disabled;");
-}
-
 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
 {
 	int major;
@@ -1162,7 +1150,15 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 	info->sector_size = sector_size;
 	info->physical_sector_size = physical_sector_size;
 
-	xlvbd_flush(info);
+	blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
+			      info->feature_fua ? true : false);
+
+	pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
+		info->gd->disk_name, flush_info(info),
+		"persistent grants:", info->feature_persistent ?
+		"enabled;" : "disabled;", "indirect descriptors:",
+		info->max_indirect_segments ? "enabled;" : "disabled;",
+		"bounce buffer:", info->bounce ? "enabled" : "disabled;");
 
 	if (info->vdisk_info & VDISK_READONLY)
 		set_disk_ro(gd, 1);
@@ -1622,13 +1618,6 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 				       info->gd->disk_name, op_name(bret.operation));
 				blkif_req(req)->error = BLK_STS_NOTSUPP;
 			}
-			if (unlikely(blkif_req(req)->error)) {
-				if (blkif_req(req)->error == BLK_STS_NOTSUPP)
-					blkif_req(req)->error = BLK_STS_OK;
-				info->feature_fua = 0;
-				info->feature_flush = 0;
-				xlvbd_flush(info);
-			}
 			fallthrough;
 		case BLKIF_OP_READ:
 		case BLKIF_OP_WRITE:
-- 
2.43.0