On 06/29/2017 04:25 PM, Christoph Hellwig wrote:
> This is based on the old idea and code from Milosz Tanski. With the
> aio nowait code it becomes mostly trivial now.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/aio.c | 6 ------
> fs/btrfs/file.c | 2 +-
> fs/ext4/file.c | 6 +++---
> fs/xfs/xfs_file.c | 11 +++++++++--
> include/linux/fs.h | 6 +++---
> 5 files changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index dcad3a66748c..d93daa076726 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1593,12 +1593,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
> goto out_put_req;
> }
>
> - if ((req->common.ki_flags & IOCB_NOWAIT) &&
> - !(req->common.ki_flags & IOCB_DIRECT)) {
> - ret = -EOPNOTSUPP;
> - goto out_put_req;
> - }
> -
> ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
> if (unlikely(ret)) {
> pr_debug("EFAULT: aio_key\n");
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index 59e2dccdf75b..f82dad241b39 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -3088,7 +3088,7 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
>
> static int btrfs_file_open(struct inode *inode, struct file *filp)
> {
> - filp->f_mode |= FMODE_AIO_NOWAIT;
> + filp->f_mode |= FMODE_NOWAIT;
> return generic_file_open(inode, filp);
> }
>
We should modify the NOWAIT check in btrfs_file_write_iter() to return
-EAGAIN for buffered writes.
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 58e2eeaa0bc4..5330ea99681a 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -223,6 +223,8 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (IS_DAX(inode))
> return ext4_dax_write_iter(iocb, from);
> #endif
> + if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
> + return -EAGAIN;
>
> if (!inode_trylock(inode)) {
> if (iocb->ki_flags & IOCB_NOWAIT)
> @@ -455,9 +457,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
> return ret;
> }
>
> - /* Set the flags to support nowait AIO */
> - filp->f_mode |= FMODE_AIO_NOWAIT;
> -
> + filp->f_mode |= FMODE_NOWAIT;
> return dquot_file_open(inode, filp);
> }
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 17f27a2fb5e2..1068f0b01090 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -259,7 +259,11 @@ xfs_file_buffered_aio_read(
>
> trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
>
> - xfs_ilock(ip, XFS_IOLOCK_SHARED);
> + if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EAGAIN;
> + xfs_ilock(ip, XFS_IOLOCK_SHARED);
> + }
> ret = generic_file_read_iter(iocb, to);
> xfs_iunlock(ip, XFS_IOLOCK_SHARED);
>
> @@ -636,6 +640,9 @@ xfs_file_buffered_aio_write(
> int enospc = 0;
> int iolock;
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EAGAIN;
> +
> write_retry:
> iolock = XFS_IOLOCK_EXCL;
> xfs_ilock(ip, iolock);
> @@ -911,7 +918,7 @@ xfs_file_open(
> return -EFBIG;
> if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
> return -EIO;
> - file->f_mode |= FMODE_AIO_NOWAIT;
> + file->f_mode |= FMODE_NOWAIT;
> return 0;
> }
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 65adbddb3163..a78834bedb61 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -144,8 +144,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
> /* File was opened by fanotify and shouldn't generate fanotify events */
> #define FMODE_NONOTIFY ((__force fmode_t)0x4000000)
>
> -/* File is capable of returning -EAGAIN if AIO will block */
> -#define FMODE_AIO_NOWAIT ((__force fmode_t)0x8000000)
> +/* File is capable of returning -EAGAIN if I/O will block */
> +#define FMODE_NOWAIT ((__force fmode_t)0x8000000)
>
> /*
> * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
> @@ -3092,7 +3092,7 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, int flags)
> return -EOPNOTSUPP;
>
> if (flags & RWF_NOWAIT) {
> - if (!(ki->ki_filp->f_mode & FMODE_AIO_NOWAIT))
> + if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
> return -EOPNOTSUPP;
> ki->ki_flags |= IOCB_NOWAIT;
> }
>
--
Goldwyn
