block: add back plugging in __blkdev_direct_IO

This allows sending larger than 1 MB requests to devices that support
large I/O sizes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7c4507224ed66b876b5bf01fd45a6d6da8106308..206a92aab52efcc52e63d782ae7430ee92f14049 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -328,6 +328,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
        struct file *file = iocb->ki_filp;
        struct inode *inode = bdev_file_inode(file);
        struct block_device *bdev = I_BDEV(inode);
+       struct blk_plug plug;
        struct blkdev_dio *dio;
        struct bio *bio;
        bool is_read = (iov_iter_rw(iter) == READ);
@@ -353,6 +354,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
        dio->multi_bio = false;
        dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
 
+       blk_start_plug(&plug);
        for (;;) {
                bio->bi_bdev = bdev;
                bio->bi_iter.bi_sector = pos >> 9;
@@ -394,6 +396,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
                submit_bio(bio);
                bio = bio_alloc(GFP_KERNEL, nr_pages);
        }
+       blk_finish_plug(&plug);
 
        if (!dio->is_sync)
                return -EIOCBQUEUED;