diff options
| -rw-r--r-- | fs/block_dev.c | 166 |
1 files changed, 162 insertions, 4 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index a1b9abe..35cc494 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -270,11 +270,161 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, return ret; } +struct blkdev_dio { + union { + struct kiocb *iocb; + struct task_struct *waiter; + }; + size_t size; + atomic_t ref; + bool multi_bio : 1; + bool should_dirty : 1; + bool is_sync : 1; + struct bio bio; +}; + +static struct bio_set *blkdev_dio_pool __read_mostly; + +static void blkdev_bio_end_io(struct bio *bio) +{ + struct blkdev_dio *dio = bio->bi_private; + bool should_dirty = dio->should_dirty; + + if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) { + if (bio->bi_error && !dio->bio.bi_error) + dio->bio.bi_error = bio->bi_error; + } else { + if (!dio->is_sync) { + struct kiocb *iocb = dio->iocb; + ssize_t ret = dio->bio.bi_error; + + if (likely(!ret)) { + ret = dio->size; + iocb->ki_pos += ret; + } + + dio->iocb->ki_complete(iocb, ret, 0); + bio_put(&dio->bio); + } else { + struct task_struct *waiter = dio->waiter; + + WRITE_ONCE(dio->waiter, NULL); + wake_up_process(waiter); + } + } + + if (should_dirty) { + bio_check_pages_dirty(bio); + } else { + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) + put_page(bvec->bv_page); + bio_put(bio); + } +} + static ssize_t -blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) +__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); + unsigned blkbits = blksize_bits(bdev_logical_block_size(bdev)); + struct blkdev_dio *dio; + struct bio *bio; + bool is_read = (iov_iter_rw(iter) == READ); + loff_t pos = iocb->ki_pos; + blk_qc_t qc = BLK_QC_T_NONE; + int ret; + + if ((pos | iov_iter_alignment(iter)) & ((1 << blkbits) - 1)) + return -EINVAL; + + bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, blkdev_dio_pool); + bio_get(bio); /* extra ref for the completion handler */ + + dio = container_of(bio, struct blkdev_dio, bio); + dio->is_sync = is_sync_kiocb(iocb); + if (dio->is_sync) + dio->waiter = current; + else + dio->iocb = iocb; + + dio->size = 0; + dio->multi_bio = false; + dio->should_dirty = is_read && (iter->type == ITER_IOVEC); + + for (;;) { + bio->bi_bdev = bdev; + bio->bi_iter.bi_sector = pos >> blkbits; + bio->bi_private = dio; + bio->bi_end_io = blkdev_bio_end_io; + + ret = bio_iov_iter_get_pages(bio, iter); + if (unlikely(ret)) { + bio->bi_error = ret; + bio_endio(bio); + break; + } + + if (is_read) { + bio->bi_opf = REQ_OP_READ; + if (dio->should_dirty) + bio_set_pages_dirty(bio); + } else { + bio->bi_opf = dio_bio_write_op(iocb); + task_io_account_write(bio->bi_iter.bi_size); + } + + dio->size += bio->bi_iter.bi_size; + pos += bio->bi_iter.bi_size; + + nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); + if (!nr_pages) { + qc = submit_bio(bio); + break; + } + + if (!dio->multi_bio) { + dio->multi_bio = true; + atomic_set(&dio->ref, 2); + } else { + atomic_inc(&dio->ref); + } + + submit_bio(bio); + bio = bio_alloc(GFP_KERNEL, nr_pages); + } + + if (!dio->is_sync) + return -EIOCBQUEUED; + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(dio->waiter)) + break; + + if (!(iocb->ki_flags & IOCB_HIPRI) || + !blk_mq_poll(bdev_get_queue(bdev), qc)) + io_schedule(); + } + __set_current_state(TASK_RUNNING); + + ret = dio->bio.bi_error; + if (likely(!ret)) { + ret = dio->size; + iocb->ki_pos += ret; + } + + bio_put(&dio->bio); + return ret; +} + +static ssize_t +blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) +{ int nr_pages; nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1); @@ -282,10 +432,18 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) return 0; if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES) return __blkdev_direct_IO_simple(iocb, iter, nr_pages); - return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, - blkdev_get_block, NULL, NULL, - DIO_SKIP_DIO_COUNT); + + return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES)); +} + +static __init int blkdev_init(void) +{ + blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio)); + if (!blkdev_dio_pool) + return -ENOMEM; + return 0; } +module_init(blkdev_init); int __sync_blockdev(struct block_device *bdev, int wait) { |
