From: Fernando Luis Vázquez Cao Date: Thu, 14 Aug 2008 07:59:13 +0000 (+0200) Subject: virtio_blk: use a wrapper function to access io context information of IO requests X-Git-Tag: v2.6.28-rc1~733^2~115 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=766ca4428d1239a970926856c447310c9c191af2;p=karo-tx-linux.git virtio_blk: use a wrapper function to access io context information of IO requests struct request has an ioprio member but it is never updated because currently bios do not hold io context information. The implication of this is that virtio_blk ends up passing useless information to the backend driver. That said, some IO schedulers such as CFQ do store io context information in struct request, but use private members for that, which means that that information cannot be directly accessed in a IO scheduler-independent way. This patch adds a function to obtain the ioprio of a request. We should avoid accessing ioprio directly and use this function instead, so that its users do not have to care about future changes in block layer structures or what the currently active IO controller is. This patch does not introduce any functional changes but paves the way for future clean-ups and enhancements. Signed-off-by: Fernando Luis Vazquez Cao Acked-by: Rusty Russell Signed-off-by: Jens Axboe --- diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 42251095134f..879506a2c234 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -84,11 +84,11 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk, if (blk_fs_request(vbr->req)) { vbr->out_hdr.type = 0; vbr->out_hdr.sector = vbr->req->sector; - vbr->out_hdr.ioprio = vbr->req->ioprio; + vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); } else if (blk_pc_request(vbr->req)) { vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; vbr->out_hdr.sector = 0; - vbr->out_hdr.ioprio = vbr->req->ioprio; + vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); } else { /* We don't put anything else in the queue. */ BUG(); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index f131776f029e..490ce458b031 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -232,6 +232,11 @@ struct request { struct request *next_rq; }; +static inline unsigned short req_get_ioprio(struct request *req) +{ + return req->ioprio; +} + /* * State information carried for REQ_TYPE_PM_SUSPEND and REQ_TYPE_PM_RESUME * requests. Some step values could eventually be made generic.