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    SubjectRe: [PATCH] disk quotas fail when /etc/mtab is symlinked to /proc/mounts
    Mark Bellon wrote:

    > Andrew Morton wrote:
    >
    >> Mark Bellon <mbellon@mvista.com> wrote:
    >>
    >>
    >>> If /etc/mtab is a regular file all of the mount options (of a file
    >>> system) are written to /etc/mtab by the mount command. The quota
    >>> tools look there for the quota strings for their operation. If,
    >>> however, /etc/mtab is a symlink to /proc/mounts (a "good thing" in
    >>> some environments) the tools don't write anything - they assume the
    >>> kernel will take care of things.
    >>>
    >>> While the quota options are sent down to the kernel via the mount
    >>> system call and the file system codes handle them properly
    >>> unfortunately there is no code to echo the quota strings into
    >>> /proc/mounts and the quota tools fail in the symlink case.
    >>>
    >>
    >>
    >> hm. Perhaps others with operational experience in that area can
    >> comment.
    >>
    >>
    > OK.
    >
    >>
    >>
    >>> The attached patchs modify the EXT[2|3] and [X|J]FS codes to add the
    >>> necessary hooks. The show_options function of each file system in
    >>> these patches currently deal with only those things that seemed
    >>> related to quotas; especially in the EXT3 case more can be done
    >>> (later?).
    >>>
    >>
    >>
    >> It seems sad to do it in each filesystem. Is there no way in which
    >> we can
    >> do this for all filesystems, in a single place in the VFS?
    >>
    >>
    > Each file system must be able to echo it's own FS specific options,
    > hence the show_options hook (XFS is a good example). EXT3 has it's own
    > form of journalled quota file options, hence the need for the specific
    > hook.
    >
    > The "older style" (e.g. "usrquota", "grpquota", "quota") could be done
    > generically but a FS might want any number of quota options. The few
    > lines of code in each file system didn't seem so bad especially if the
    > show_function start echoing more.

    Followup comment/through...

    If we want /proc/mounts to really replace /etc/mtab in the general case,
    always using it as a symlink, the file system codes will all need the
    show_options hook - they will need to echo all of their private options
    duplicating, as closely as possible, what would have been written to the
    /etc/mtab regular file.

    mark

    mark

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