On Sun, Apr 20, 2014 at 03:53:05PM +0200, Kay Sievers wrote: > On Sun, Apr 20, 2014 at 5:36 AM, Zbigniew Jędrzejewski-Szmek > <zbys...@in.waw.pl> wrote: > > > Hi Kay, > > it seems that handles are not crucial, and the simplified version below > > works too. Is there something I'm missing? > > The name_to_handle API works properly with bind mounts, it's the more > reliable API. > > It also was intentional to support any filesystem with the prefix > devtmpfs*, like "devtmpfs2" or whatever it might be named in the > future. > > What actual problem are we trying to solve here with not requiring a > common kernel config option? We want/need it in other places too, and > the current fallback logic to figure out the mount point is really not > that great with bind mounts. We just need the fallback for filesystems > which do not support the API, but most common and tmpfs/devtmpfs do. > > I don't necessarily see the point in supporting the idea of the > kernel's uber-configurability and the massive pain it causes for tools > to make things work. Yeah, I'm just trying to reduce the confusion that people experience on kernels without CONFIG_FHANDLE.
What about this: --------8<------------------------------------------------------------- Subject: [PATCH] udev: assume /dev is devtmpfs if name_to_handle_at is not implemented We have a bunch of reports from people who have a custom kernel and are confused why udev is not running. This raises the possibility of a false positive when running on a kernel without CONFIG_FHANDLE but in a container. Nevertheless, this caes should be easier to diagnose than the opposite of running on bare metal with the same kernel. https://bugzilla.redhat.com/show_bug.cgi?id=1072966 Also, if we find a mountpoint with a matching id, and it doesn't have devtmpfs mounted, return false. --- src/libudev/libudev-monitor.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c index 3f7436b..dd5f862 100644 --- a/src/libudev/libudev-monitor.c +++ b/src/libudev/libudev-monitor.c @@ -117,9 +117,16 @@ static bool udev_has_devtmpfs(struct udev *udev) { h = alloca(MAX_HANDLE_SZ); h->handle_bytes = MAX_HANDLE_SZ; r = name_to_handle_at(AT_FDCWD, "/dev", h, &mount_id, 0); - if (r < 0) - return false; + if (r < 0) { + if (errno == ENOSYS || errno == ENOTSUP) { + /* This kernel or file system does not support + * name_to_handle_at(). */ + log_warning("name_to_handle_at syscall failed, assuming /dev is volatile."); + return true; + } + return false; + } f = fopen("/proc/self/mountinfo", "re"); if (!f) @@ -139,8 +146,7 @@ static bool udev_has_devtmpfs(struct udev *udev) { continue; /* accept any name that starts with the currently expected type */ - if (startswith(e + 3, "devtmpfs")) - return true; + return startswith(e + 3, "devtmpfs"); } return false; -- 1.8.5.2 --------8<------------------------------------------------------------- ? Zbyszek _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
