Re: bug with multiple mounts of filesystems in 2.6

[Trond Myklebust]

På må , 26/07/2004 klokka 12:29, skreiv John S J Anderson:
>   Hi --
> 
>   We're working on migrating to the 2.6 kernel series, and one big
>   problem has popped up: we have a number of NFS mounts that are
>   mounted read-only in one location and read-write in a distinct
>   location (on the same machine). With 2.4 series kernels, this worked
>   without issue, but with 2.6, it doesn't: it's not possible to mount
>   the same filesystem twice with different options for each mount; the
>   two mount points have to share the same mount options.

That behaviour is no longer supported as it meant that you would have
different superblocks (and hence different out-of-sync caches) between
the 2 mountpoint. It is in any case not a behaviour that is supported on
any other Linux filesystems.

If you want readonly to be an exception, then you will have to move the
MS_RDONLY flag from being a superblock option to being a vfsmount
option, then propagate that vfsmount information down to all the tests
of IS_RDONLY(inode). Not a trivial task, and not one that looms high on
my list of priorities...

Cheers,
  Trond
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