Add a simple proxy implementation of init_dma_buf_io_ctx() forwarding the call to a new struct block_device_operations operation. Also reject dma-buf backed iterators for buffered IO.
Reviewed-by: Christoph Hellwig <[email protected]> [pavel: reject dma-buf without O_DIRECT] Signed-off-by: Pavel Begunkov <[email protected]> --- block/fops.c | 19 +++++++++++++++++++ include/linux/blkdev.h | 2 ++ 2 files changed, 21 insertions(+) diff --git a/block/fops.c b/block/fops.c index 56bbacf6e317..3c403afb0f64 100644 --- a/block/fops.c +++ b/block/fops.c @@ -767,6 +767,9 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) ret = direct_write_fallback(iocb, from, ret, blkdev_buffered_write(iocb, from)); } else { + if (unlikely(iov_iter_is_dmabuf_map(from))) + return -EOPNOTSUPP; + /* * Take i_rwsem and invalidate_lock to avoid racing with * set_blocksize changing i_blkbits/folio order and punching @@ -821,6 +824,8 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to) if (ret < 0 || !count) goto reexpand; } + if (unlikely(iov_iter_is_dmabuf_map(to))) + return -EOPNOTSUPP; /* * Take i_rwsem and invalidate_lock to avoid racing with set_blocksize @@ -924,6 +929,19 @@ static int blkdev_mmap_prepare(struct vm_area_desc *desc) return generic_file_mmap_prepare(desc); } +static int blkdev_init_dma_buf_io_ctx(struct file *file, + struct dma_buf_io_ctx *ctx) +{ + struct block_device *bdev = file_bdev(file); + struct gendisk *disk = bdev->bd_disk; + + if (!(file->f_flags & O_DIRECT)) + return -EINVAL; + if (!disk->fops->init_dma_buf_io_ctx) + return -EINVAL; + return disk->fops->init_dma_buf_io_ctx(bdev, ctx); +} + const struct file_operations def_blk_fops = { .open = blkdev_open, .release = blkdev_release, @@ -942,6 +960,7 @@ const struct file_operations def_blk_fops = { .fallocate = blkdev_fallocate, .uring_cmd = blkdev_uring_cmd, .fop_flags = FOP_BUFFER_RASYNC | FOP_DONTCACHE, + .init_dma_buf_io_ctx = blkdev_init_dma_buf_io_ctx, }; static __init int blkdev_init(void) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 9213a5716f95..9f4c92e51dc9 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1682,6 +1682,8 @@ struct block_device_operations { /* returns the length of the identifier or a negative errno: */ int (*get_unique_id)(struct gendisk *disk, u8 id[16], enum blk_unique_id id_type); + int (*init_dma_buf_io_ctx)(struct block_device *, + struct dma_buf_io_ctx *); struct module *owner; const struct pr_ops *pr_ops; -- 2.54.0
