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

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;
 }

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;
 }

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)

drivers/block/xen-blkfront.c

@@ -489,7 +489,7 @@ static int blkif_queue_request(struct request *req)
 
 			if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 			    (i % SEGS_PER_INDIRECT_FRAME == 0)) {
-				unsigned long pfn;
+				unsigned long uninitialized_var(pfn);
 
 				if (segments)
 					kunmap_atomic(segments);
@@ -2011,6 +2011,10 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
 	bdev = bdget_disk(disk, 0);
 
+	if (!bdev) {
+		WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
+		goto out_mutex;
+	}
 	if (bdev->bd_openers)
 		goto out;
 
@@ -2041,6 +2045,7 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
 out:
 	bdput(bdev);
+out_mutex:
 	mutex_unlock(&blkfront_mutex);
 }
 

drivers/md/md.c

@@ -776,16 +776,10 @@ void md_super_wait(struct mddev *mddev)
 	finish_wait(&mddev->sb_wait, &wq);
 }
 
-static void bi_complete(struct bio *bio, int error)
-{
-	complete((struct completion*)bio->bi_private);
-}
-
 int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 		 struct page *page, int rw, bool metadata_op)
 {
 	struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, rdev->mddev);
-	struct completion event;
 	int ret;
 
 	rw |= REQ_SYNC;
@@ -801,11 +795,7 @@ int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 	else
 		bio->bi_sector = sector + rdev->data_offset;
 	bio_add_page(bio, page, size, 0);
-	init_completion(&event);
-	bio->bi_private = &event;
-	bio->bi_end_io = bi_complete;
-	submit_bio(rw, bio);
-	wait_for_completion(&event);
+	submit_bio_wait(rw, bio);
 
 	ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
 	bio_put(bio);

fs/btrfs/check-integrity.c

@@ -333,7 +333,6 @@ static void btrfsic_release_block_ctx(struct btrfsic_block_data_ctx *block_ctx);
 static int btrfsic_read_block(struct btrfsic_state *state,
 			      struct btrfsic_block_data_ctx *block_ctx);
 static void btrfsic_dump_database(struct btrfsic_state *state);
-static void btrfsic_complete_bio_end_io(struct bio *bio, int err);
 static int btrfsic_test_for_metadata(struct btrfsic_state *state,
 				     char **datav, unsigned int num_pages);
 static void btrfsic_process_written_block(struct btrfsic_dev_state *dev_state,
@@ -1687,7 +1686,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
 	for (i = 0; i < num_pages;) {
 		struct bio *bio;
 		unsigned int j;
-		DECLARE_COMPLETION_ONSTACK(complete);
 
 		bio = btrfs_io_bio_alloc(GFP_NOFS, num_pages - i);
 		if (!bio) {
@@ -1698,8 +1696,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
 		}
 		bio->bi_bdev = block_ctx->dev->bdev;
 		bio->bi_sector = dev_bytenr >> 9;
-		bio->bi_end_io = btrfsic_complete_bio_end_io;
-		bio->bi_private = &complete;
 
 		for (j = i; j < num_pages; j++) {
 			ret = bio_add_page(bio, block_ctx->pagev[j],
@@ -1712,12 +1708,7 @@ static int btrfsic_read_block(struct btrfsic_state *state,
 			       "btrfsic: error, failed to add a single page!\n");
 			return -1;
 		}
-		submit_bio(READ, bio);
-
-		/* this will also unplug the queue */
-		wait_for_completion(&complete);
-
-		if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+		if (submit_bio_wait(READ, bio)) {
 			printk(KERN_INFO
 			       "btrfsic: read error at logical %llu dev %s!\n",
 			       block_ctx->start, block_ctx->dev->name);
@@ -1740,11 +1731,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
 	return block_ctx->len;
 }
 
-static void btrfsic_complete_bio_end_io(struct bio *bio, int err)
-{
-	complete((struct completion *)bio->bi_private);
-}
-
 static void btrfsic_dump_database(struct btrfsic_state *state)
 {
 	struct list_head *elem_all;
@@ -3008,14 +2994,12 @@ int btrfsic_submit_bh(int rw, struct buffer_head *bh)
 	return submit_bh(rw, bh);
 }
 
-void btrfsic_submit_bio(int rw, struct bio *bio)
+static void __btrfsic_submit_bio(int rw, struct bio *bio)
 {
 	struct btrfsic_dev_state *dev_state;
 
-	if (!btrfsic_is_initialized) {
-		submit_bio(rw, bio);
+	if (!btrfsic_is_initialized)
 		return;
-	}
 
 	mutex_lock(&btrfsic_mutex);
 	/* since btrfsic_submit_bio() is also called before
@@ -3106,10 +3090,20 @@ void btrfsic_submit_bio(int rw, struct bio *bio)
 	}
 leave:
 	mutex_unlock(&btrfsic_mutex);
+}
 
+void btrfsic_submit_bio(int rw, struct bio *bio)
+{
+	__btrfsic_submit_bio(rw, bio);
 	submit_bio(rw, bio);
 }
 
+int btrfsic_submit_bio_wait(int rw, struct bio *bio)
+{
+	__btrfsic_submit_bio(rw, bio);
+	return submit_bio_wait(rw, bio);
+}
+
 int btrfsic_mount(struct btrfs_root *root,
 		  struct btrfs_fs_devices *fs_devices,
 		  int including_extent_data, u32 print_mask)

fs/btrfs/check-integrity.h

@@ -22,9 +22,11 @@
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 int btrfsic_submit_bh(int rw, struct buffer_head *bh);
 void btrfsic_submit_bio(int rw, struct bio *bio);
+int btrfsic_submit_bio_wait(int rw, struct bio *bio);
 #else
 #define btrfsic_submit_bh submit_bh
 #define btrfsic_submit_bio submit_bio
+#define btrfsic_submit_bio_wait submit_bio_wait
 #endif
 
 int btrfsic_mount(struct btrfs_root *root,

fs/btrfs/extent_io.c

@@ -1952,11 +1952,6 @@ static int free_io_failure(struct inode *inode, struct io_failure_record *rec,
 	return err;
 }
 
-static void repair_io_failure_callback(struct bio *bio, int err)
-{
-	complete(bio->bi_private);
-}
-
 /*
  * this bypasses the standard btrfs submit functions deliberately, as
  * the standard behavior is to write all copies in a raid setup. here we only
@@ -1973,7 +1968,6 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
 {
 	struct bio *bio;
 	struct btrfs_device *dev;
-	DECLARE_COMPLETION_ONSTACK(compl);
 	u64 map_length = 0;
 	u64 sector;
 	struct btrfs_bio *bbio = NULL;
@@ -1990,8 +1984,6 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
 	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
 	if (!bio)
 		return -EIO;
-	bio->bi_private = &compl;
-	bio->bi_end_io = repair_io_failure_callback;
 	bio->bi_size = 0;
 	map_length = length;
 
@@ -2012,10 +2004,8 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
 	}
 	bio->bi_bdev = dev->bdev;
 	bio_add_page(bio, page, length, start - page_offset(page));
-	btrfsic_submit_bio(WRITE_SYNC, bio);
-	wait_for_completion(&compl);
 
-	if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+	if (btrfsic_submit_bio_wait(WRITE_SYNC, bio)) {
 		/* try to remap that extent elsewhere? */
 		bio_put(bio);
 		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);