Re: NFS-mounted, read-only /dev unusable in 2.6

[Neil Brown]

On Wednesday August 4, fsteiner-mail@xxxxxxxxxxxxxx wrote:
> Neil Brown wrote:
> 
> >>But I just tried to reproduce this on 2.6.7-rc2 (it's what my
> >>workstation happens to be running) and I can't. I can mount an
> >>nfs-exported /dev from both 2.4 and 2.6 servers read-only and
> >>I can open devices on that read-only mount just fine.
> > 
> > 
> > Yes, it was a bug in the NFS server in 2.6 that was fixed fairly
> > recently.
> 
> Hi Neil,
> 
> it still occurs in 2.6.8rc3 in some way:

.... It looks like it was *so* recent that I haven't actually
submitted the patch yet :-(

I think someone reported it, I sent them a patch, and never got a
confirmation that it worked (or missed it if I did) so the patch
didn't progres..

Try the following.

Thanks,
NeilBrown


### Diffstat output
 ./fs/nfsd/vfs.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff ./fs/nfsd/vfs.c~current~ ./fs/nfsd/vfs.c
--- ./fs/nfsd/vfs.c~current~	2004-07-26 09:54:15.000000000 +1000
+++ ./fs/nfsd/vfs.c	2004-07-23 13:37:38.000000000 +1000
@@ -376,12 +376,13 @@ static struct accessmap	nfs3_anyaccess[]
 	 * to the server to check for access for things like /dev/null
 	 * (which really, the server doesn't care about).  So
 	 * We provide simple access checking for them, looking
-	 * mainly at mode bits
+	 * mainly at mode bits, and we make sure to ignore read-only
+	 * filesystem checks
 	 */
     {	NFS3_ACCESS_READ,	MAY_READ			},
     {	NFS3_ACCESS_EXECUTE,	MAY_EXEC			},
-    {	NFS3_ACCESS_MODIFY,	MAY_WRITE			},
-    {	NFS3_ACCESS_EXTEND,	MAY_WRITE			},
+    {	NFS3_ACCESS_MODIFY,	MAY_WRITE|MAY_LOCAL_ACCESS	},
+    {	NFS3_ACCESS_EXTEND,	MAY_WRITE|MAY_LOCAL_ACCESS	},
 
     {	0,			0				}
 };
-
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