On 06/04/2017 10:38 PM, NeilBrown wrote:
>
> /usr/bin/umount will always pass a canonical name
> to umount.nfs, so it is safe to disable canonicalization.
>
> When umounting an NFS filesystem, it is generally safest to
> not "stat" the mountpoint at all as that can block
> indefinitely. umount() will not block, but lstat() etc can.
> By disabling canonicalization in libmount, we discourage it
> from ever calling 'stat' family operations, and thus reduce
> the chance of a hang.
>
> Note that to be fully effective, this requires changes to
> util-linux which have not yet been accepted.
> When both that change and this are in effect, automounters
> can use "umount -c $PATH" to safely unmount a filesystem
> without blocking.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Committed...
steved.
> ---
> utils/mount/mount_libmount.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/utils/mount/mount_libmount.c b/utils/mount/mount_libmount.c
> index 1f01f7f7a4e7..2d4065759a6c 100644
> --- a/utils/mount/mount_libmount.c
> +++ b/utils/mount/mount_libmount.c
> @@ -188,6 +188,7 @@ static int umount_main(struct libmnt_context *cxt, int argc, char **argv)
> };
>
> mnt_context_init_helper(cxt, MNT_ACT_UMOUNT, 0);
> + mnt_context_disable_canonicalize(cxt, 1);
>
> while ((c = getopt_long (argc, argv, "fvnrlh", longopts, NULL)) != -1) {
>
>
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