On Sat, Jan 24, 2026 at 10:06:32AM +0000, Gleb Popov wrote:
> The branch main has been updated by arrowd:
>
> URL:
> https://cgit.FreeBSD.org/src/commit/?id=10037d0978f8b16dc6746b0b942788e5edc6e84f
>
> commit 10037d0978f8b16dc6746b0b942788e5edc6e84f
> Author: Gleb Popov <[email protected]>
> AuthorDate: 2025-10-14 16:15:50 +0000
> Commit: Gleb Popov <[email protected]>
> CommitDate: 2026-01-24 10:06:16 +0000
>
> fusefs: Implement support for the auto_unmount option kernel-side
>
> libfuse clients may pass the "-o auto_unmount" flag to ensure that the
> mountpoint
> will get unmounted even if the server terminate abnormally. Without this
> flag
> sending KILL to a FUSE daemon leaves its mountpoint mounted.
>
> Approved by: asomers
> Differential Revision: https://reviews.freebsd.org/D53086
> ---
> sbin/mount_fusefs/mount_fusefs.8 | 5 ++++-
> sbin/mount_fusefs/mount_fusefs.c | 2 ++
> sys/fs/fuse/fuse_device.c | 6 +++++-
> sys/fs/fuse/fuse_ipc.h | 3 ++-
> sys/fs/fuse/fuse_vfsops.c | 1 +
> 5 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/sbin/mount_fusefs/mount_fusefs.8
> b/sbin/mount_fusefs/mount_fusefs.8
> index 44f7e029dec6..a463f6463a29 100644
> --- a/sbin/mount_fusefs/mount_fusefs.8
> +++ b/sbin/mount_fusefs/mount_fusefs.8
> @@ -32,7 +32,7 @@
> .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> .\" SUCH DAMAGE.
> .\"
> -.Dd October 9, 2021
> +.Dd January 24, 2026
> .Dt MOUNT_FUSEFS 8
> .Os
> .Sh NAME
> @@ -171,6 +171,9 @@ to the file system name as reported by
> .Xr statfs 2 .
> This option can be used to identify the file system implemented by
> .Ar fuse_daemon .
> +.It Cm auto_unmount
> +Instructs the kernel to unmount the mount point when the FUSE device gets
> closed.
> +This ensures a proper cleanup if the FUSE daemon exits abnormally.
> .El
> .El
> .Pp
> diff --git a/sbin/mount_fusefs/mount_fusefs.c
> b/sbin/mount_fusefs/mount_fusefs.c
> index 2d65494421ef..a4e33ad6878e 100644
> --- a/sbin/mount_fusefs/mount_fusefs.c
> +++ b/sbin/mount_fusefs/mount_fusefs.c
> @@ -84,6 +84,8 @@ static struct mntopt mopts[] = {
> { "automounted", 0, ALTF_AUTOMOUNTED, 1 },
> #define ALTF_INTR 0x200
> { "intr", 0, ALTF_INTR, 1 },
> + #define ALTF_AUTOUNMOUNT 0x400
> + { "auto_unmount", 0, ALTF_AUTOUNMOUNT, 1 },
> /* Linux specific options, we silently ignore them */
> { "fd=", 0, 0x00, 1 },
> { "rootmode=", 0, 0x00, 1 },
> diff --git a/sys/fs/fuse/fuse_device.c b/sys/fs/fuse/fuse_device.c
> index 41387de3ce71..2c1e19953dfd 100644
> --- a/sys/fs/fuse/fuse_device.c
> +++ b/sys/fs/fuse/fuse_device.c
> @@ -65,7 +65,6 @@
> #include <sys/module.h>
> #include <sys/systm.h>
> #include <sys/errno.h>
> -#include <sys/param.h>
> #include <sys/kernel.h>
> #include <sys/conf.h>
> #include <sys/uio.h>
> @@ -177,6 +176,11 @@ fdata_dtor(void *arg)
> fuse_lck_mtx_unlock(fdata->ms_mtx);
> FUSE_UNLOCK();
>
> + if (fdata->mp && fdata->dataflags & FSESS_AUTO_UNMOUNT) {
if (fdata->mp != NULL && (fdata->dataflags & FSESS_AUTO_UNMOUNT) != 0) {
> + vfs_ref(fdata->mp);
Don't you need to take the reference when the fdata is created and mp member
is initialized, and not here?
What guarantees that the mp is still ours?
In fact, I think that you should use vfs_busy() and not vfs_ref(),
since what prevents mp from being unmounted under us?
> + dounmount(fdata->mp, MNT_FORCE, curthread);
> + }
> +
> fdata_trydestroy(fdata);
> }
>
> diff --git a/sys/fs/fuse/fuse_ipc.h b/sys/fs/fuse/fuse_ipc.h
> index d9d79f38c269..98af84951561 100644
> --- a/sys/fs/fuse/fuse_ipc.h
> +++ b/sys/fs/fuse/fuse_ipc.h
> @@ -242,8 +242,9 @@ struct fuse_data {
> #define FSESS_WARN_INODE_MISMATCH 0x4000000 /* ino != nodeid */
> #define FSESS_MNTOPTS_MASK ( \
> FSESS_DAEMON_CAN_SPY | FSESS_PUSH_SYMLINKS_IN | \
> - FSESS_DEFAULT_PERMISSIONS | FSESS_INTR)
> + FSESS_DEFAULT_PERMISSIONS | FSESS_INTR | FSESS_AUTO_UNMOUNT)
> #define FSESS_SETXATTR_EXT 0x8000000 /* extended
> fuse_setxattr_in */
> +#define FSESS_AUTO_UNMOUNT 0x10000000 /* perform unmount when server
> dies */
>
> extern int fuse_data_cache_mode;
>
> diff --git a/sys/fs/fuse/fuse_vfsops.c b/sys/fs/fuse/fuse_vfsops.c
> index 0ff79913128a..a5118aa7675f 100644
> --- a/sys/fs/fuse/fuse_vfsops.c
> +++ b/sys/fs/fuse/fuse_vfsops.c
> @@ -337,6 +337,7 @@ fuse_vfsop_mount(struct mount *mp)
> FUSE_FLAGOPT(push_symlinks_in, FSESS_PUSH_SYMLINKS_IN);
> FUSE_FLAGOPT(default_permissions, FSESS_DEFAULT_PERMISSIONS);
> FUSE_FLAGOPT(intr, FSESS_INTR);
> + FUSE_FLAGOPT(auto_unmount, FSESS_AUTO_UNMOUNT);
>
> (void)vfs_scanopt(opts, "max_read=", "%u", &max_read);
> (void)vfs_scanopt(opts, "linux_errnos", "%d", &linux_errnos);
