Date: Sat, 28 Jun 2003 17:27:24 -0700 From: Kris Kennaway <kris@obsecurity.org> To: Ian Dowse <iedowse@maths.tcd.ie> Cc: freebsd-arch@freebsd.org Subject: Re: Unmounting by filesystem ID Message-ID: <20030629002724.GA61860@rot13.obsecurity.org> In-Reply-To: <200306282254.aa83607@salmon.maths.tcd.ie> References: <200306282254.aa83607@salmon.maths.tcd.ie>
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--UugvWAfsgieZRqgk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 28, 2003 at 10:54:04PM +0100, Ian Dowse wrote: >=20 > The patch below adds a new mount flag MNT_BYFSID that can be used > to unmount a filesystem by specifying its filesystem ID instead of > a path. The umount utility is changed to use this mechanism by > default. This approach has a number of advantages: >=20 > - It avoids any lookup operations that could potentially block > forever, so filesystems such as NFS can be reliably unmounted > even if the server is not responding but looking up the root node > would require an RPC (maybe to an underlying filesystem). > - The filesystem specification is unambiguous, so umount(8) can > be sure that it is unmounting the correct filesystem (more > work in umount(8) may be required here). > - Detached filesystems can be unmounted. If a filesystem becomes > detached from the filesystem hierarchy because the underlying > filesystem got unmounted, it does not require a reboot to unmount > it. >=20 > Since unmounting by a path name is now only required for compatibility, > in that case unmount() now just does a string comparison to find > the correct filesystem. Also, this patch only affects unmounting; > a similar approach could be applied to MNT_UPDATE mount operations. >=20 > I would like to commit this during the next few days. Any comments > or suggestions? The approach sounds great to me; these are long-standing annoyances in FreeBSD. Kris --UugvWAfsgieZRqgk Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE+/jJsWry0BWjoQKURAtgxAKCOYWvNJVyogbJL8zlVna2NvzMeugCg/ac3 iVsxySX53MlvGDdoTuTu4Uc= =inDX -----END PGP SIGNATURE----- --UugvWAfsgieZRqgk--
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