From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [PATCH manpages] umount.2: revise MNT_FORCE description. Date: Tue, 08 Aug 2017 15:49:58 +1000 Message-ID: <87mv7asj5l.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1010185718==" Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: systemd-devel-bounces@lists.freedesktop.org Sender: "systemd-devel" To: mtk.manpages@gmail.com Cc: linux-fsdevel@vger.kernel.org, linux-man@vger.kernel.org, systemd-devel@freedesktop.org List-Id: linux-man@vger.kernel.org --===============1010185718== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable 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 =2D-- Explanation derived from examination of source code. Cc to systemd devel in relation to comment I just posted: https://github.com/systemd/systemd/commit/0c08f5cde749bd2818475e487109cd0d4= 13452df 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 =2D-- 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)" =2DForce unmount even if busy. =2DThis can cause data loss. =2D(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 =2D-=20 2.14.0.rc0.dirty --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlmJUQgACgkQOeye3VZi gbn0OBAAkSSZnbLZZ+ZFGjqUKtva2sXR7VIY0Enf/d0KDrzFRFfpMD3NCyv+xQfJ 9KJZxEDBcQfdyQNtGUC99MSpBK1zvhKglZ+KA/fJNBcR07AQeDks8BbFvtp/eMka xb3i1Rp/98IknH6pmZP7wg/zPomGMgWVl2AOFP3n0T/ZTiUo7TkqCJ5TLESp/C5S n3cnXjaun62vxHRyGwn2LMy0dMsO2wziAsvq6/kTai0aCLO04dyu3ylJ+Y8HzkJc hY/tEQV/9Ws1yG6p42JuWHRhz4WsZfHtWrzPT/kLtGAkMj3CTzlOYRc/TILsrhFJ Hsgsd9ZBNX5DXPCiFq+cviGXjtWNGjEKhJWykmVewAtv5MKjgFQ0ApElXUQOmfMG jJeQaFPGHCe2DRInL4xg4hH5gTHNuTrk2Ef4zsxoNvn+tGTMvJSQhY5FEiuEHu4G BiBTcR2mA2uZKFyT07pR0SkBiqCuizzBoTUefjlbN6s13vQyxHQL9nw0YzirpTQR yvHk+UC7+NE74DpLp9FL6W3G4IZ+4E16gRYZiTkbHDl2f8iSFKhZ1GiVVnAXOStA ry2hlqV6qZexG4qq2ekkTXDs0PsNSIQ8LuVxWxhByi1LgMi7UudcokwTc9TQRov1 SC/vi8rMCa1cFp6VT2+PybFH1qmpNZcz7SlBv7/19DVPi3Db0ZM= =C+YH -----END PGP SIGNATURE----- --=-=-=-- --===============1010185718== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18Kc3lzdGVtZC1k ZXZlbCBtYWlsaW5nIGxpc3QKc3lzdGVtZC1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0 cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9zeXN0ZW1kLWRldmVs Cg== --===============1010185718==--