Re: [PATCH 13/19] Add fuse_session_set_debug() to enable debug output without foreground

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Mar 23, 2026 at 06:45:08PM +0100, Bernd Schubert wrote:
> From: Bernd Schubert <bschubert@ddn.com>
> 
> One might want to print debug out in background mode, which the command
> line parameter does not easily allow. Or one might want to enable and
> disable at run time.
> 
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>

Woot!  Have been wanting this for fuse4fs for a while :)
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  include/fuse_lowlevel.h | 12 ++++++++++++
>  lib/fuse_lowlevel.c     |  5 +++++
>  lib/fuse_versionscript  |  1 +
>  3 files changed, 18 insertions(+)
> 
> diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
> index d8626f85bdaf497534cd2835a589e30f1f4e2466..d85929e291a77de8caad7d6b3d9ac5b092ce0e62 100644
> --- a/include/fuse_lowlevel.h
> +++ b/include/fuse_lowlevel.h
> @@ -2441,6 +2441,18 @@ int fuse_session_receive_buf(struct fuse_session *se, struct fuse_buf *buf);
>   */
>  void fuse_session_want_sync_init(struct fuse_session *se);
>  
> +/**
> + * Enable debug output
> + *
> + * This allows to enable debug output without a command line parameter and
> + * without the enforcement of the command line parameter to run in foreground.
> + * The daemon needs to handle either fuse_log output via stderr, or
> + * redirection to its own logs or via syslog.
> + *
> + * @param se the session
> + */
> +void fuse_session_set_debug(struct fuse_session *se);
> +
>  /**
>   * Check if the request is submitted through fuse-io-uring
>   */
> diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
> index b10def03f3666757d312f87f177a560483691d6f..a7293a3898c37c3877eadf965d310ae2aa5cc2d1 100644
> --- a/lib/fuse_lowlevel.c
> +++ b/lib/fuse_lowlevel.c
> @@ -5007,3 +5007,8 @@ void fuse_session_want_sync_init(struct fuse_session *se)
>  		return;
>  	se->want_sync_init = true;
>  }
> +
> +void fuse_session_set_debug(struct fuse_session *se)
> +{
> +	se->debug = 1;
> +}
> diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
> index f1765d39e13bc9b1f53e625b9a091c5fa53f5afd..64bf75ac2cb252d066ac301be8fc024b59f903ac 100644
> --- a/lib/fuse_versionscript
> +++ b/lib/fuse_versionscript
> @@ -230,6 +230,7 @@ FUSE_3.19 {
>  		fuse_daemonize_start;
>  		fuse_daemonize_signal;
>  		fuse_daemonize_active;
> +		fuse_session_set_debug;
>  } FUSE_3.18;
>  
>  # Local Variables:
> 
> -- 
> 2.43.0
> 
>