Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block layer fixes from Jens Axboe:
 "A small collection of fixes for the current series. It contains:

   - A fix for a use-after-free of a request in blk-mq.  From Ming Lei

   - A fix for a blk-mq bug that could attempt to dereference a NULL rq
     if allocation failed

   - Two xen-blkfront small fixes

   - Cleanup of submit_bio_wait() type uses in the kernel, unifying
     that.  From Kent

   - A fix for 32-bit blkg_rwstat reading.  I apologize for this one
     looking mangled in the shortlog, it's entirely my fault for missing
     an empty line between the description and body of the text"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: fix use-after-free of request
  blk-mq: fix dereference of rq->mq_ctx if allocation fails
  block: xen-blkfront: Fix possible NULL ptr dereference
  xen-blkfront: Silence pfn maybe-uninitialized warning
  block: submit_bio_wait() conversions
  Update of blkg_stat and blkg_rwstat may happen in bh context

3 files changed, 15 insertions, 28 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 1610b22edf0..86154eab952 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -435,9 +435,9 @@ static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 	uint64_t v;
 
 	do {
-		start = u64_stats_fetch_begin(&stat->syncp);
+		start = u64_stats_fetch_begin_bh(&stat->syncp);
 		v = stat->cnt;
-	} while (u64_stats_fetch_retry(&stat->syncp, start));
+	} while (u64_stats_fetch_retry_bh(&stat->syncp, start));
 
 	return v;
 }
@@ -508,9 +508,9 @@ static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 	struct blkg_rwstat tmp;
 
 	do {
-		start = u64_stats_fetch_begin(&rwstat->syncp);
+		start = u64_stats_fetch_begin_bh(&rwstat->syncp);
 		tmp = *rwstat;
-	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
+	} while (u64_stats_fetch_retry_bh(&rwstat->syncp, start));
 
 	return tmp;
 }
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 331e627301e..fb6f3c0ffa4 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -502,15 +502,6 @@ void blk_abort_flushes(struct request_queue *q)
 	}
 }
 
-static void bio_end_flush(struct bio *bio, int err)
-{
-	if (err)
-		clear_bit(BIO_UPTODATE, &bio->bi_flags);
-	if (bio->bi_private)
-		complete(bio->bi_private);
-	bio_put(bio);
-}
-
 /**
  * blkdev_issue_flush - queue a flush
  * @bdev:	blockdev to issue flush for
@@ -526,7 +517,6 @@ static void bio_end_flush(struct bio *bio, int err)
 int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 		sector_t *error_sector)
 {
-	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q;
 	struct bio *bio;
 	int ret = 0;
@@ -548,13 +538,9 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 		return -ENXIO;
 
 	bio = bio_alloc(gfp_mask, 0);
-	bio->bi_end_io = bio_end_flush;
 	bio->bi_bdev = bdev;
-	bio->bi_private = &wait;
 
-	bio_get(bio);
-	submit_bio(WRITE_FLUSH, bio);
-	wait_for_completion_io(&wait);
+	ret = submit_bio_wait(WRITE_FLUSH, bio);
 
 	/*
 	 * The driver must store the error location in ->bi_sector, if
@@ -564,9 +550,6 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 	if (error_sector)
 		*error_sector = bio->bi_sector;
 
-	if (!bio_flagged(bio, BIO_UPTODATE))
-		ret = -EIO;
-
 	bio_put(bio);
 	return ret;
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index cdc629cf075..c79126e1103 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -202,10 +202,12 @@ static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
 		if (rq) {
 			blk_mq_rq_ctx_init(q, ctx, rq, rw);
 			break;
-		} else if (!(gfp & __GFP_WAIT))
-			break;
+		}
 
 		blk_mq_put_ctx(ctx);
+		if (!(gfp & __GFP_WAIT))
+			break;
+
 		__blk_mq_run_hw_queue(hctx);
 		blk_mq_wait_for_tags(hctx->tags);
 	} while (1);
@@ -222,7 +224,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 		return NULL;
 
 	rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
-	blk_mq_put_ctx(rq->mq_ctx);
+	if (rq)
+		blk_mq_put_ctx(rq->mq_ctx);
 	return rq;
 }
 
@@ -235,7 +238,8 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
 		return NULL;
 
 	rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
-	blk_mq_put_ctx(rq->mq_ctx);
+	if (rq)
+		blk_mq_put_ctx(rq->mq_ctx);
 	return rq;
 }
 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
@@ -308,12 +312,12 @@ void blk_mq_complete_request(struct request *rq, int error)
 
 	blk_account_io_completion(rq, bytes);
 
+	blk_account_io_done(rq);
+
 	if (rq->end_io)
 		rq->end_io(rq, error);
 	else
 		blk_mq_free_request(rq);
-
-	blk_account_io_done(rq);
 }
 
 void __blk_mq_end_io(struct request *rq, int error)