Re: [PATCH] shm fs v2 against 2.3.41

[GOTO Masanori <gotom@debian.or.jp>]

Calling shmget( key, size, shmflg ) with size = 0,
I got an error EINVAL. The below patch fix it,
please apply into 2.3.41+shmfs14 patch.

---------------------
--- linux-2.3.41_shmfs14/ipc/shm.c      Tue Feb  1 18:49:02 2000
+++ linux-2.3.41_shmfs14_fixed/ipc/shm.c        Tue Feb  1 18:57:52 2000
@@ -660,7 +660,7 @@
                return -EINVAL;
        }
 
-       if (size < SHMMIN)
+       if ((size != 0) && (size < SHMMIN))
                return -EINVAL;
 
        down(&shm_ids.sem);
---------------------

And now I have a question:
I guess almost all users have no shmpath (default: /var/shm),
and they maybe make a dir and have to mount it.
IMHO, it is better to change that sysv shared memory works
samely, whenever shmfs is not mounted. Is it feasible, 
or only my mistaken ?


From: Christoph Rohland <hans-christoph.rohland@sap.com>
Subject: [PATCH] shm fs v2 against 2.3.41
> Hi Folks,
> 
> Here is my newest version of shm over a filesystem:
> 
> Changes to the previous versio:
> 
> - It does not try to autodetect the path any more. Per default it
>   expects to be mounted at /var/shm. If you mount it somewhere else,
>   put the new path into /proc/sys/kernel/shmpath
> - No more /proc/sys/kernel/{shmall,shmmni}. Use mount options
>   nr_blocks and nr_pages. You can change these parameters with remount.
> - You can set the initial mode of the directory with mount option 'mode'.
> - It frees all objects on umount.
> 
> I tested the shm fs heavily on 2.3.40+some patches to make smp and
> page_cache stable. It survived one day swap test.

Regards,
-- GOTO Masanori
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