diff options
| -rw-r--r-- | drivers/block/xen-blkfront.c | 49 |
1 files changed, 36 insertions, 13 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 20759817ad57..b536a9cef917 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -97,6 +97,7 @@ struct blkfront_info struct blk_shadow shadow[BLK_RING_SIZE]; unsigned long shadow_free; unsigned int feature_flush; + unsigned int flush_op; int is_ready; }; @@ -250,8 +251,7 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode, /* * Generate a Xen blkfront IO request from a blk layer request. Reads - * and writes are handled as expected. Since we lack a loose flush - * request, we map flushes into a full ordered barrier. + * and writes are handled as expected. * * @req: a request struct */ @@ -293,14 +293,13 @@ static int blkif_queue_request(struct request *req) if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { /* - * Ideally we could just do an unordered - * flush-to-disk, but all we have is a full write - * barrier at the moment. However, a barrier write is + * Ideally we can do an unordered flush-to-disk. In case the + * backend onlysupports barriers, use that. A barrier request * a superset of FUA, so we can implement it the same * way. (It's also a FLUSH+FUA, since it is * guaranteed ordered WRT previous writes.) */ - ring_req->operation = BLKIF_OP_WRITE_BARRIER; + ring_req->operation = info->flush_op; } ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg); @@ -433,8 +432,11 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) static void xlvbd_flush(struct blkfront_info *info) { blk_queue_flush(info->rq, info->feature_flush); - printk(KERN_INFO "blkfront: %s: barriers %s\n", + printk(KERN_INFO "blkfront: %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"); } @@ -720,15 +722,20 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; switch (bret->operation) { + case BLKIF_OP_FLUSH_DISKCACHE: case BLKIF_OP_WRITE_BARRIER: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { - printk(KERN_WARNING "blkfront: %s: write barrier op failed\n", + printk(KERN_WARNING "blkfront: %s: write %s op failed\n", + info->flush_op == BLKIF_OP_WRITE_BARRIER ? + "barrier" : "flush disk cache", info->gd->disk_name); error = -EOPNOTSUPP; } if (unlikely(bret->status == BLKIF_RSP_ERROR && info->shadow[id].req.nr_segments == 0)) { - printk(KERN_WARNING "blkfront: %s: empty write barrier op failed\n", + printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n", + info->flush_op == BLKIF_OP_WRITE_BARRIER ? + "barrier" : "flush disk cache", info->gd->disk_name); error = -EOPNOTSUPP; } @@ -736,6 +743,7 @@ 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 */ @@ -1100,7 +1108,7 @@ static void blkfront_connect(struct blkfront_info *info) unsigned long sector_size; unsigned int binfo; int err; - int barrier; + int barrier, flush; switch (info->connected) { case BLKIF_STATE_CONNECTED: @@ -1140,6 +1148,9 @@ static void blkfront_connect(struct blkfront_info *info) return; } + info->feature_flush = 0; + info->flush_op = 0; + err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-barrier", "%d", &barrier, NULL); @@ -1151,11 +1162,23 @@ static void blkfront_connect(struct blkfront_info *info) * * If there are barriers, then we use flush. */ - info->feature_flush = 0; - - 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. + */ + err = xenbus_gather(XBT_NIL, info->xbdev->otherend, + "feature-flush-cache", "%d", &flush, + NULL); + if (!err && flush) { + info->feature_flush = REQ_FLUSH; + info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; + } + err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size); if (err) { xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", |