Re: [PATCH RFC 07/10] xfs: Add xfs_file_dio_write_atomic()

John Garry
2025-02-10T16:59:53Z

On 04/02/2025 12:01, John Garry wrote:
> +static noinline ssize_t
> +xfs_file_dio_write_atomic(
> + struct xfs_inode *ip,
> + struct kiocb *iocb,
> + struct iov_iter *from)
> +{
> + unsigned int iolock = XFS_IOLOCK_SHARED;
> + bool use_cow = false;
> + unsigned int dio_flags;
> + ssize_t ret;
> +
> +retry:
> + ret = xfs_ilock_iocb_for_write(iocb, &iolock);
> + if (ret)
> + return ret;
> +
> + ret = xfs_file_write_checks(iocb, from, &iolock);
> + if (ret)
> + goto out_unlock;
> +
> + if (use_cow) {
> + ret = xfs_reflink_unshare(ip, iocb->ki_pos,
> + iov_iter_count(from));
> + if (ret)
> + goto out_unlock;
> + }
> +
> + trace_xfs_file_direct_write(iocb, from);
> + if (use_cow)
> + dio_flags = IOMAP_DIO_ATOMIC_COW;

note to self:

We should also set IOMAP_DIO_FORCE_WAIT and call inode_dio_wait() here,
similar to xfs_file_dio_write_unaligned()

> + else
> + dio_flags = 0;
> +
> + ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
> + &xfs_dio_write_ops, dio_flags, NULL, 0);
> +
> + if (ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT) && !use_cow) {
> + xfs_iunlock(ip, iolock);
> + iolock = XFS_IOLOCK_EXCL;
> + use_cow = true;
> + goto retry;
> + }
> +
> +out_unlock:
> + if (iolock)
> + xfs_iunlock(ip, iolock);
> + return ret;
> +}
> +