Date: Mon, 25 Aug 1997 02:28:50 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, current@FreeBSD.ORG Subject: Re: another mount arg incompatibility Message-ID: <199708241628.CAA16264@godzilla.zeta.org.au>
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I wrote: >After `mount -t msdos /dev/fd0 /mnt' (which works and gives a mode of >root.wheel for the mount point), `mount -t msdos -o '' /dev/fd0 /mnt' >changes the mode to 4022327920.8338. I should have written: After `mount -t msdos /dev/fd0 /mnt' (which works and gives ownership of root.wheel for the mount point), `mount -u -o '' /dev/fd0 /mnt' changes the ownership to 4022327920.8338. `mount -u -t msdos ...' fails early because mount_msdos doesn't support the MNT_UPDATE flag although msdosfs sort of supports it. Support for MNT_FORCE is similarly broken. Support for MNT_SYNCHRONOUS is slightly more broken - it is a general vfs flag (it mainly affects vn_write(), so it belongs in MNT_STD more that some of the other options in MNT_STD (it doesn't apply to inherently readonly file systems, but neither does MNT_NOATIME, and support for quotas is not standard...). Perhaps the support shouldn't be limited in individual mount utilities. However, many kernel mount routines just ignore unsupported flags. `mount -u -o '' /dev/fd0 /mnt' is immune to the above problem because mount(8) calls mount(2) directly. mount(2) somehow gets as far as msdosfs_mount(). msdosfs_mount() then uses invalid mount args. Another bug: after `mount -t msdos /dev/fd0 /mnt' #works `mount -t ext2fs /dev/wd0s1 /mnt' #works? it seems to be impossible to unmount either file system. Bruce
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