mainline inclusion from mainline-v6.10 commit 9086b2d9e9f3da0b0f939aa1d7ff74e9bf5b54c8 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IB81UH Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------------- Alyssa Ross <hi@alyssa.is> requested that virtiofs notifies userspace when filesytems become available. This can be used to detect when a filesystem with a given tag is hotplugged, for example. uevents allow userspace to detect changes without resorting to polling. The tag is included as a uevent property so it's easy for userspace to identify the filesystem in question even when the sysfs directory goes away during removal. Here are example uevents: # udevadm monitor -k -p KERNEL[111.113221] add /fs/virtiofs/2 (virtiofs) ACTION=add DEVPATH=/fs/virtiofs/2 SUBSYSTEM=virtiofs TAG=test KERNEL[165.527167] remove /fs/virtiofs/2 (virtiofs) ACTION=remove DEVPATH=/fs/virtiofs/2 SUBSYSTEM=virtiofs TAG=test Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Shuai Wu <wushuai51@huawei.com> --- fs/fuse/virtio_fs.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index 99b6113bb..62a446037 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -306,6 +306,8 @@ static int virtio_fs_add_instance(struct virtio_device *vdev, mutex_unlock(&virtio_fs_mutex); + kobject_uevent(&fs->kobj, KOBJ_ADD); + return 0; } @@ -1565,9 +1567,22 @@ static struct file_system_type virtio_fs_type = { .kill_sb = virtio_kill_sb, }; +static int virtio_fs_uevent(const struct kobject *kobj, struct kobj_uevent_env *env) +{ + const struct virtio_fs *fs = container_of(kobj, struct virtio_fs, kobj); + + add_uevent_var(env, "TAG=%s", fs->tag); + return 0; +} + +static const struct kset_uevent_ops virtio_fs_uevent_ops = { + .uevent = virtio_fs_uevent, +}; + static int __init virtio_fs_sysfs_init(void) { - virtio_fs_kset = kset_create_and_add("virtiofs", NULL, fs_kobj); + virtio_fs_kset = kset_create_and_add("virtiofs", &virtio_fs_uevent_ops, + fs_kobj); if (!virtio_fs_kset) return -ENOMEM; return 0; -- 2.33.0