Re: [PATCH 4/4] iotests: add tests for FUSE-over-io_uring

[Stefan Hajnoczi <stefanha@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 4930 bytes --]

On Fri, Aug 29, 2025 at 10:50:25PM -0400, Brian Song wrote:
> To test FUSE-over-io_uring, set the environment variable
> FUSE_OVER_IO_URING=1. This applies only when using the
> 'fuse' protocol.
> 
> $ FUSE_OVER_IO_URING=1 ./check -fuse
> 
> Suggested-by: Kevin Wolf <kwolf@redhat.com>
> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Brian Song <hibriansong@gmail.com>
> ---
>  tests/qemu-iotests/check     |  2 ++
>  tests/qemu-iotests/common.rc | 45 +++++++++++++++++++++++++++---------
>  2 files changed, 36 insertions(+), 11 deletions(-)
> 
> diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
> index 545f9ec7bd..c6fa0f9e3d 100755
> --- a/tests/qemu-iotests/check
> +++ b/tests/qemu-iotests/check
> @@ -94,6 +94,8 @@ def make_argparser() -> argparse.ArgumentParser:
>          mg.add_argument('-' + fmt, dest='imgfmt', action='store_const',
>                          const=fmt, help=f'test {fmt}')
>  
> +    # To test FUSE-over-io_uring, set the environment variable
> +    # FUSE_OVER_IO_URING=1. This applies only when using the 'fuse' protocol
>      protocol_list = ['file', 'rbd', 'nbd', 'ssh', 'nfs', 'fuse']
>      g_prt = p.add_argument_group(
>          '  image protocol options',
> diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
> index e977cb4eb6..f8b79c3810 100644
> --- a/tests/qemu-iotests/common.rc
> +++ b/tests/qemu-iotests/common.rc
> @@ -539,17 +539,38 @@ _make_test_img()
>          touch "$export_mp"
>          rm -f "$SOCK_DIR/fuse-output"
>  
> -        # Usually, users would export formatted nodes.  But we present fuse as a
> -        # protocol-level driver here, so we have to leave the format to the
> -        # client.
> -        # Switch off allow-other, because in general we do not need it for
> -        # iotests.  The default allow-other=auto has the downside of printing a
> -        # fusermount error on its first attempt if allow_other is not
> -        # permissible, which we would need to filter.

This comment applies to both branches of the if statement. I think
keeping it here is slightly better.

> -        QSD_NEED_PID=y $QSD \
> -              --blockdev file,node-name=export-node,filename=$img_name,discard=unmap \
> -              --export fuse,id=fuse-export,node-name=export-node,mountpoint="$export_mp",writable=on,growable=on,allow-other=off \
> -              &
> +        if [ -n "$FUSE_OVER_IO_URING" ]; then
> +            nr_cpu=$(nproc 2>/dev/null || echo 1)
> +            nr_iothreads=$((nr_cpu / 2))
> +            if [ $nr_iothreads -lt 1 ]; then
> +                nr_iothreads=1
> +            fi

Please add a comment explaining that the purpose of this configuration
based on the number of CPUs is to test multiple IOThreads when the host
allows it, since that is a more interesting case then just 1 IOThread.
Many other configurations are possible as well, but not all of them can
be tested because the test matrix would be large.

> +
> +            iothread_args=""
> +            iothread_export_args=""
> +            for ((i=0; i<$nr_iothreads; i++)); do
> +                iothread_args="$iothread_args --object iothread,id=iothread$i"
> +                iothread_export_args="$iothread_export_args,iothread.$i=iothread$i"
> +            done
> +
> +            QSD_NEED_PID=y $QSD \
> +                    $iothread_args \
> +                    --blockdev file,node-name=export-node,filename=$img_name,discard=unmap \
> +                    --export fuse,id=fuse-export,node-name=export-node,mountpoint="$export_mp",writable=on,growable=on,allow-other=off,io-uring=on$iothread_export_args \
> +                &
> +        else
> +            # Usually, users would export formatted nodes.  But we present fuse as a
> +            # protocol-level driver here, so we have to leave the format to the
> +            # client.
> +            # Switch off allow-other, because in general we do not need it for
> +            # iotests.  The default allow-other=auto has the downside of printing a
> +            # fusermount error on its first attempt if allow_other is not
> +            # permissible, which we would need to filter.
> +            QSD_NEED_PID=y $QSD \
> +                --blockdev file,node-name=export-node,filename=$img_name,discard=unmap \
> +                --export fuse,id=fuse-export,node-name=export-node,mountpoint="$export_mp",writable=on,growable=on,allow-other=off \
> +                &
> +        fi
>  
>          pidfile="$QEMU_TEST_DIR/qemu-storage-daemon.pid"
>  
> @@ -592,6 +613,8 @@ _rm_test_img()
>  
>          kill "${FUSE_PIDS[index]}"
>  
> +        sleep 1
> +

What is the purpose of this sleep command?

>          # Wait until the mount is gone
>          timeout=10 # *0.5 s
>          while true; do
> -- 
> 2.45.2
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]