Re: [RFC 5/5] block: implement io_uring discard cmd

[Jens Axboe <axboe@kernel.dk>]

On 8/14/24 4:45 AM, Pavel Begunkov wrote:
> diff --git a/block/ioctl.c b/block/ioctl.c
> index c7a3e6c6f5fa..f7f9c4c6d6b5 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -11,6 +11,8 @@
>  #include <linux/blktrace_api.h>
>  #include <linux/pr.h>
>  #include <linux/uaccess.h>
> +#include <linux/pagemap.h>
> +#include <linux/io_uring/cmd.h>
>  #include "blk.h"
>  
>  static int blkpg_do_ioctl(struct block_device *bdev,
> @@ -744,4 +746,96 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>  
>  	return ret;
>  }
> +
> +struct blk_cmd {
> +	blk_status_t status;
> +	bool nowait;
> +};
> +
> +static void blk_cmd_complete(struct io_uring_cmd *cmd, unsigned int issue_flags)
> +{
> +	struct blk_cmd *bc = io_uring_cmd_to_pdu(cmd, struct blk_cmd);
> +	int res = blk_status_to_errno(bc->status);
> +
> +	if (res == -EAGAIN && bc->nowait)
> +		io_uring_cmd_issue_blocking(cmd);
> +	else
> +		io_uring_cmd_done(cmd, res, 0, issue_flags);
> +}
> +
> +static void bio_cmd_end(struct bio *bio)
> +{
> +	struct io_uring_cmd *cmd = bio->bi_private;
> +	struct blk_cmd *bc = io_uring_cmd_to_pdu(cmd, struct blk_cmd);
> +
> +	if (unlikely(bio->bi_status) && !bc->status)
> +		bc->status = bio->bi_status;
> +
> +	io_uring_cmd_do_in_task_lazy(cmd, blk_cmd_complete);
> +	bio_put(bio);
> +}
> +
> +static int blkdev_cmd_discard(struct io_uring_cmd *cmd,
> +			      struct block_device *bdev,
> +			      uint64_t start, uint64_t len, bool nowait)
> +{
> +	sector_t sector = start >> SECTOR_SHIFT;
> +	sector_t nr_sects = len >> SECTOR_SHIFT;
> +	struct bio *prev = NULL, *bio;
> +	int err;
> +
> +	err = blk_validate_discard(bdev, file_to_blk_mode(cmd->file),
> +				   start, len);
> +	if (err)
> +		return err;
> +	err = filemap_invalidate_pages(bdev->bd_mapping, start,
> +					start + len - 1, nowait);
> +	if (err)
> +		return err;
> +
> +	while ((bio = blk_alloc_discard_bio(bdev, &sector, &nr_sects,
> +					    GFP_KERNEL))) {
> +		if (nowait) {
> +			if (unlikely(nr_sects)) {
> +				bio_put(bio);
> +				return -EAGAIN;
> +			}
> +			bio->bi_opf |= REQ_NOWAIT;
> +		}
> +		prev = bio_chain_and_submit(prev, bio);
> +	}
> +	if (!prev)
> +		return -EFAULT;
> +
> +	prev->bi_private = cmd;
> +	prev->bi_end_io = bio_cmd_end;
> +	submit_bio(prev);
> +	return -EIOCBQUEUED;
> +}
> +
> +int blkdev_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
> +{
> +	struct block_device *bdev = I_BDEV(cmd->file->f_mapping->host);
> +	struct blk_cmd *bc = io_uring_cmd_to_pdu(cmd, struct blk_cmd);
> +	const struct io_uring_sqe *sqe = cmd->sqe;
> +	u32 cmd_op = cmd->cmd_op;
> +	uint64_t start, len;
> +
> +	if (unlikely(sqe->ioprio || sqe->__pad1 || sqe->len ||
> +		     sqe->rw_flags || sqe->file_index))
> +		return -EINVAL;
> +
> +	bc->status = BLK_STS_OK;
> +	bc->nowait = issue_flags & IO_URING_F_NONBLOCK;
> +
> +	start = READ_ONCE(sqe->addr);
> +	len = READ_ONCE(sqe->addr3);
> +
> +	switch (cmd_op) {
> +	case BLOCK_URING_CMD_DISCARD:
> +		return blkdev_cmd_discard(cmd, bdev, start, len, bc->nowait);
> +	}
> +	return -EINVAL;
> +}

This is inside the CONFIG_COMPAT section, which doesn't seem right.

-- 
Jens Axboe