Re: Random "File size limit exceeded" under 2.4

[Ken Brownfield <brownfld@irridia.com>]

FWIW, I've been using this over-engineered, under-tested command line
utility to run e2fsck on our older distributions:

	http://web.irridia.com/info/linux/unflimit.c

It works like "nice" or "time", but sets the proper RLIM_INFINITY
filesize limit for the inheriting subshell.  For example:

	unflimit e2fsck /dev/sda3

The boot-time fscks work fine, but in multiuser I'm extremely lucky to
get it to work without this.

The kernel patch below would work, I expect, but I think it's not
necessarily the Right Thing To Do.  If Andrew is right, is anyone
looking at why block devices (or fsck?) are honoring the filesize limit?

Thanks,
-- 
Ken.
brownfld@irridia.com

On Wed, Dec 05, 2001 at 10:33:19PM +0000, Miquel van Smoorenburg wrote:
| In article <3C0E813D.F5B1F84E@zip.com.au>,
| Andrew Morton  <akpm@zip.com.au> wrote:
| >Derek Glidden wrote:
| >> 
| >> I've been experiencing random and occasional encounters with "File size
| >> limit exceeded" errors under 2.4 kernels when trying to make
| >> filesystems.
| >
| >I don't know if anyone has come forth to fix this yet.
| >
| >Apparently it's something to do with your shell setting
| >rlimits, and block devices are (bogusly) honouring those
| >settings.
| 
| Perhaps the old app is calling sys_old_getrlimit() from
| linux/kernel/sys.c. It truncates rlimits to 0x7FFFFFFF
| if it's bigger than that. 0x7FFFFFFF used to be the old
| RLIM_INFINITY in 2.2 [actually, ((long)(~0UL>>1))]. In
| 2.4, RLIM_INFINITY is (~0UL).
| 
| So if you call sys_setrlimit() with the old RLIM_INFINITY from 2.2
| OR with the result from sys_old_getrlimit(), then the new limit
| will be 0x7FFFFFFF instead of unlimited.
| 
| Looks like someone forgot to implement sys_old_setrlimit(),
| which would have been the right thing to do.
| 
| Now all we can do is to hack sys_setrlimit and let it translate
| 0x7FFFFFFF to RLIM_INFINITY.
| 
| The following untested and uncompiled patch might do it, or not...
| 
| --- linux-2.4.17-pre2/kernel/sys.c.orig	Tue Sep 18 23:10:43 2001
| +++ linux-2.4.17-pre2/kernel/sys.c	Wed Dec  5 23:30:50 2001
| @@ -1120,6 +1120,16 @@
|  		return -EINVAL;
|  	if(copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
|  		return -EFAULT;
| +#if !defined(__ia64__)
| +	/*
| +	 * 	In 2.2, RLIMIT_INFINITY was defined as ((long)(~0UL>>1)).
| +	 * 	Reckognize it and translate it to the new RLIMIT_INFINITY.
| +	 */
| +	if ((long)new_rlim.rlim_cur == ((long)(~0UL>>1)))
| +		new_rlim.rlim_cur = RLIMIT_INFINITY;
| +	if ((long)new_rlim.rlim_max == ((long)(~0UL>>1)))
| +		new_rlim.rlim_max = RLIMIT_INFINITY;
| +#endif
|  	old_rlim = current->rlim + resource;
|  	if (((new_rlim.rlim_cur > old_rlim->rlim_max) ||
|  	     (new_rlim.rlim_max > old_rlim->rlim_max)) &&
| 
| Mike.
| -- 
| "Only two things are infinite, the universe and human stupidity,
|  and I'm not sure about the former" -- Albert Einstein.
| 
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