On Fri, Aug 09, 2024 at 06:35:27PM +0100, Mark Harmstone wrote:
> Adds an io_uring interface for asynchronous encoded reads, using the
> same interface as for the ioctl. To use this you would use an SQE opcode
> of IORING_OP_URING_CMD, the cmd_op would be BTRFS_IOC_ENCODED_READ, and
> addr would point to the userspace address of the
> btrfs_ioctl_encoded_io_args struct. As with the ioctl, you need to have
> CAP_SYS_ADMIN for this to work.
What is the point if this doesn't actually do anything but returning
-EIOCBQUEUED?
Note that that the internals of the btrfs encoded read is built
around kiocbs anyway, so you might as well turn things upside down,
implement a real async io_uring cmd and just wait for it to complete
to implement the existing synchronous ioctl.
>
> Signed-off-by: Mark Harmstone <maharmstone@xxxxxx>
> ---
> fs/btrfs/file.c | 1 +
> fs/btrfs/ioctl.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/ioctl.h | 1 +
> 3 files changed, 50 insertions(+)
>
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index f9d76072398d..974f9e85b46e 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -3850,6 +3850,7 @@ const struct file_operations btrfs_file_operations = {
> .compat_ioctl = btrfs_compat_ioctl,
> #endif
> .remap_file_range = btrfs_remap_file_range,
> + .uring_cmd = btrfs_uring_cmd,
> };
>
> int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0493272a7668..8f5cc7d1429c 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -29,6 +29,7 @@
> #include <linux/fileattr.h>
> #include <linux/fsverity.h>
> #include <linux/sched/xacct.h>
> +#include <linux/io_uring/cmd.h>
> #include "ctree.h"
> #include "disk-io.h"
> #include "export.h"
> @@ -4648,6 +4649,53 @@ static int btrfs_ioctl_encoded_write(struct file *file, void __user *argp, bool
> return ret;
> }
>
> +static void btrfs_uring_encoded_read_cb(struct io_uring_cmd *cmd,
> + unsigned int issue_flags)
> +{
> + int ret;
> +
> + ret = btrfs_ioctl_encoded_read(cmd->file, (void __user *)cmd->sqe->addr,
> + false);
> +
> + io_uring_cmd_done(cmd, ret, 0, issue_flags);
> +}
> +
> +static void btrfs_uring_encoded_read_compat_cb(struct io_uring_cmd *cmd,
> + unsigned int issue_flags)
> +{
> + int ret;
> +
> + ret = btrfs_ioctl_encoded_read(cmd->file, (void __user *)cmd->sqe->addr,
> + true);
> +
> + io_uring_cmd_done(cmd, ret, 0, issue_flags);
> +}
> +
> +static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd,
> + unsigned int issue_flags)
> +{
> + if (issue_flags & IO_URING_F_COMPAT)
> + io_uring_cmd_complete_in_task(cmd, btrfs_uring_encoded_read_compat_cb);
> + else
> + io_uring_cmd_complete_in_task(cmd, btrfs_uring_encoded_read_cb);
> +
> + return -EIOCBQUEUED;
> +}
> +
> +int btrfs_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
> +{
> + switch (cmd->cmd_op) {
> + case BTRFS_IOC_ENCODED_READ:
> +#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
> + case BTRFS_IOC_ENCODED_READ_32:
> +#endif
> + return btrfs_uring_encoded_read(cmd, issue_flags);
> + }
> +
> + io_uring_cmd_done(cmd, -EINVAL, 0, issue_flags);
> + return -EIOCBQUEUED;
> +}
> +
> long btrfs_ioctl(struct file *file, unsigned int
> cmd, unsigned long arg)
> {
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index 2c5dc25ec670..33578f4b5f46 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -22,5 +22,6 @@ void btrfs_sync_inode_flags_to_i_flags(struct inode *inode);
> int __pure btrfs_is_empty_uuid(u8 *uuid);
> void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
> struct btrfs_ioctl_balance_args *bargs);
> +int btrfs_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);
>
> #endif
> --
> 2.44.2
>
>
---end quoted text---
