On Mon, Jan 11, 2021 at 05:12:11PM +0100, Christoph Hellwig wrote:
> Ensure we don't block on the iolock, or waiting for I/O in
> xfs_file_aio_write_checks if the caller asked to avoid that.
>
> Fixes: 29a5d29ec181 ("xfs: nowait aio support")
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_file.c | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index aa3fe89628f0f1..1470fc4f2e0255 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -355,7 +355,14 @@ xfs_file_aio_write_checks(
> if (error <= 0)
> return error;
>
> - error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + error = break_layout(inode, false);
> + if (error == -EWOULDBLOCK)
> + error = -EAGAIN;
> + } else {
> + error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
> + }
> +
> if (error)
> return error;
>
> @@ -366,7 +373,11 @@ xfs_file_aio_write_checks(
> if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
> xfs_iunlock(ip, *iolock);
> *iolock = XFS_IOLOCK_EXCL;
> - xfs_ilock(ip, *iolock);
> + error = xfs_ilock_iocb(iocb, *iolock);
> + if (error) {
> + *iolock = 0;
> + return error;
> + }
> goto restart;
> }
> /*
> @@ -388,6 +399,10 @@ xfs_file_aio_write_checks(
> isize = i_size_read(inode);
> if (iocb->ki_pos > isize) {
> spin_unlock(&ip->i_flags_lock);
> +
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EAGAIN;
> +
> if (!drained_dio) {
> if (*iolock == XFS_IOLOCK_SHARED) {
> xfs_iunlock(ip, *iolock);
> @@ -613,7 +628,8 @@ xfs_file_dio_aio_write(
> &xfs_dio_write_ops,
> is_sync_kiocb(iocb) || unaligned_io);
> out:
> - xfs_iunlock(ip, iolock);
> + if (iolock)
> + xfs_iunlock(ip, iolock);
>
> /*
> * No fallback to buffered IO after short writes for XFS, direct I/O
> @@ -652,7 +668,8 @@ xfs_file_dax_write(
> error = xfs_setfilesize(ip, pos, ret);
> }
> out:
> - xfs_iunlock(ip, iolock);
> + if (iolock)
> + xfs_iunlock(ip, iolock);
> if (error)
> return error;
>
> --
> 2.29.2
>
