On 08/08/2017 07:49 AM, NeilBrown wrote: > > MNT_FORCE does not allow a busy filesystem to be unmounted. Only > MNT_DETACH allows that. > MNT_FORCE only tries to abort pending transactions, in the hope that > might help umount not to block, > > Also, other filesystems than NFS support MNT_FORCE. > > Signed-off-by: NeilBrown <neilb@xxxxxxxx> Thanks, Neil. Applied. Cheers, Michael > --- > > Explanation derived from examination of source code. > Cc to systemd devel in relation to comment I just posted: > > https://github.com/systemd/systemd/commit/0c08f5cde749bd2818475e487109cd0d413452df > > You may want to move the "linux version when support was added" to a > comment, or discard it. > > man2/umount.2 | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/man2/umount.2 b/man2/umount.2 > index 68f76b7c6352..ccd1d07afe88 100644 > --- a/man2/umount.2 > +++ b/man2/umount.2 > @@ -61,9 +61,17 @@ unmounts a target, but allows additional > controlling the behavior of the operation: > .TP > .BR MNT_FORCE " (since Linux 2.1.116)" > -Force unmount even if busy. > -This can cause data loss. > -(Only for NFS mounts.) > +Ask the filesystem to abort pending requests before attempting the > +unmount. This may allow the unmount to complete without waiting > +for an inaccessible server. If, after aborting requests, some > +processes still have active references to the filesystem, the > +unmount will still fail. In Linux 4.12, only the filesystems > +9p (2.6.16), > +ceph (2.6.34), > +cifs (2.6.12), > +fuse (2.6.16), > +lustre (3.11), > +and NFS (2.1.116) respond to MNT_FORCE. > .TP > .BR MNT_DETACH " (since Linux 2.4.11)" > Perform a lazy unmount: make the mount point unavailable for new > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
