SCSI and ATA both need to send data to the device. In order to do this, the BIO must be allocated with room for a page to be added, and the bio needs to be passed to the discard prep function. We also need to free the page attached to the BIO before we free it. init_request_from_bio() is not currently called from a context which forbids sleeping, and to make sure it stays that was (so we don't have to use GFP_ATOMIC), add a might_sleep() to it. [hch: moved the might_sleep into the discard section, it can trigger easily for normal requests] Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> Index: linux-2.6/block/blk-barrier.c =================================================================== --- linux-2.6.orig/block/blk-barrier.c 2009-08-29 19:19:47.351880578 -0300 +++ linux-2.6/block/blk-barrier.c 2009-08-29 19:19:58.087575976 -0300 @@ -383,7 +383,7 @@ int blkdev_issue_discard(struct block_de return -EOPNOTSUPP; while (nr_sects && !ret) { - struct bio *bio = bio_alloc(gfp_mask, 0); + struct bio *bio = bio_alloc(gfp_mask, 1); if (!bio) return -ENOMEM; Index: linux-2.6/block/blk-core.c =================================================================== --- linux-2.6.orig/block/blk-core.c 2009-08-29 18:16:52.427841223 -0300 +++ linux-2.6/block/blk-core.c 2009-08-29 19:19:28.639880676 -0300 @@ -1124,10 +1124,11 @@ void init_request_from_bio(struct reques req->cmd_flags |= REQ_FAILFAST_DRIVER; if (unlikely(bio_discard(bio))) { + might_sleep(); req->cmd_flags |= REQ_DISCARD; if (bio_barrier(bio)) req->cmd_flags |= REQ_SOFTBARRIER; - req->q->prepare_discard_fn(req->q, req); + req->q->prepare_discard_fn(req->q, req, bio); } else if (unlikely(bio_barrier(bio))) req->cmd_flags |= REQ_HARDBARRIER; Index: linux-2.6/drivers/mtd/mtd_blkdevs.c =================================================================== --- linux-2.6.orig/drivers/mtd/mtd_blkdevs.c 2009-08-29 18:16:52.639841570 -0300 +++ linux-2.6/drivers/mtd/mtd_blkdevs.c 2009-08-29 18:17:22.799373769 -0300 @@ -33,7 +33,7 @@ struct mtd_blkcore_priv { }; static int blktrans_discard_request(struct request_queue *q, - struct request *req) + struct request *req, struct bio *bio) { req->cmd_type = REQ_TYPE_LINUX_BLOCK; req->cmd[0] = REQ_LB_OP_DISCARD; Index: linux-2.6/include/linux/blkdev.h =================================================================== --- linux-2.6.orig/include/linux/blkdev.h 2009-08-29 18:16:52.899841155 -0300 +++ linux-2.6/include/linux/blkdev.h 2009-08-29 18:17:22.803373020 -0300 @@ -255,7 +255,8 @@ typedef void (request_fn_proc) (struct r typedef int (make_request_fn) (struct request_queue *q, struct bio *bio); typedef int (prep_rq_fn) (struct request_queue *, struct request *); typedef void (unplug_fn) (struct request_queue *); -typedef int (prepare_discard_fn) (struct request_queue *, struct request *); +typedef int (prepare_discard_fn) (struct request_queue *, struct request *, + struct bio *bio); struct bio_vec; struct bvec_merge_data { -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html