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    SubjectRe: [PATCH] FILESYSTEMS: Delete unused "int dummy[5]" from inodes_stat_t.
    On 5/29/07, Randy Dunlap <randy.dunlap@oracle.com> wrote:
    > Robert P. J. Day wrote:
    > > On Tue, 29 May 2007, Randy Dunlap wrote:
    > >
    > >> On Tue, 29 May 2007 14:07:01 -0400 (EDT) Robert P. J. Day wrote:
    > >>
    > >>> On Tue, 29 May 2007, Andrew Morton wrote:
    > >>>
    > >>>> kernel/sysctl.c:
    > >>>>
    > >>>> {
    > >>>> .ctl_name = FS_STATINODE,
    > >>>> .procname = "inode-state",
    > >>>> .data = &inodes_stat,
    > >>>> .maxlen = 7*sizeof(int), <-----
    > >>>> .mode = 0444,
    > >>>> .proc_handler = &proc_dointvec,
    > >>>> },
    > >>>>
    > >>>> akpm:/home/akpm> cat /proc/sys/fs/inode-state
    > >>>> 608039 178454 0 0 0 0 0
    > >>>>
    > >>>> So it _is_ used: to present those five zeroes. I think this is
    > >>>> for back-compatibility with some cretaceous-era kernel.
    > >>> ah, gotcha. well, i'll leave this up to someone else to do
    > >>> anything with if they are so inclined.
    > >> There's little to be done, except possibly put a /* comment */ on
    > >> the struct's dummy line so that we don't go thru this again in N
    > >> years.
    > >
    > > so, just to clarify, what *is* the value of those trailing five
    > > zeroes? andrew suggests it's to be backward-compatible with an old
    > > kernel, which doesn't make much sense to me. it would make more sense
    > > to say that that's backward-compatible with some old userspace app
    > > that always wants to see seven values and just ignores the last five.
    >
    > Agreed, it's for compat with some (unknown) userspace app that reads
    > /proc/sys/fs/inode-state and scans for 7 (or more than 2) numbers there.
    > The mantra is "don't break userspace," so we leave the numbers there...

    Couldn't you remove the dummy member and just have the proc entry
    print out 5 dummy zeros?

    josh
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