On Tue, Aug 19, 2025 at 10:25:00AM +0200, Christoph Hellwig wrote:
> Currently the kernel will happily route io_uring requests with metadata
> to file operations that don't support it. Add a FMODE_ flag to guard
> that.
>
> Fixes: 4de2ce04c862 ("fs: introduce IOCB_HAS_METADATA for metadata")
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
It kind of feels like that f_iocb_flags should be changed so that
subsystems like block can just raise some internal flags directly
instead of grabbing a f_mode flag everytime they need to make some
IOCB_* flag conditional on the file. That would mean changing the
unconditional assigment to file->f_iocb_flags to a |= to not mask flags
raised by the kernel itself.
Then you can just push the burden of stuff like IOCB_HAS_* vs
IOCB_SUPPORTS/CAN_* to f_iocb_flags instead of the FMODE_* space.
> block/fops.c | 3 +++
> include/linux/fs.h | 3 ++-
> io_uring/rw.c | 3 +++
> 3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/block/fops.c b/block/fops.c
> index 82451ac8ff25..08e7c21bd9f1 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -7,6 +7,7 @@
> #include <linux/init.h>
> #include <linux/mm.h>
> #include <linux/blkdev.h>
> +#include <linux/blk-integrity.h>
> #include <linux/buffer_head.h>
> #include <linux/mpage.h>
> #include <linux/uio.h>
> @@ -687,6 +688,8 @@ static int blkdev_open(struct inode *inode, struct file *filp)
>
> if (bdev_can_atomic_write(bdev))
> filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
> + if (blk_get_integrity(bdev->bd_disk))
> + filp->f_mode |= FMODE_HAS_METADATA;
>
> ret = bdev_open(bdev, mode, filp->private_data, NULL, filp);
> if (ret)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index d7ab4f96d705..601d036a6c78 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -149,7 +149,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
> /* Expect random access pattern */
> #define FMODE_RANDOM ((__force fmode_t)(1 << 12))
>
> -/* FMODE_* bit 13 */
> +/* Supports IOCB_HAS_METADATA */
> +#define FMODE_HAS_METADATA ((__force fmode_t)(1 << 13))
>
> /* File is opened with O_PATH; almost nothing can be done with it */
> #define FMODE_PATH ((__force fmode_t)(1 << 14))
> diff --git a/io_uring/rw.c b/io_uring/rw.c
> index 52a5b950b2e5..af5a54b5db12 100644
> --- a/io_uring/rw.c
> +++ b/io_uring/rw.c
> @@ -886,6 +886,9 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type)
> if (req->flags & REQ_F_HAS_METADATA) {
> struct io_async_rw *io = req->async_data;
>
> + if (!(file->f_mode & FMODE_HAS_METADATA))
> + return -EINVAL;
> +
> /*
> * We have a union of meta fields with wpq used for buffered-io
> * in io_async_rw, so fail it here.
> --
> 2.47.2
>
