lkml.org 
[lkml]   [2007]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-05-29 21:13    [from the cache]
©2003-2011 Jasper Spaans