Re: NFS client broken in Linus' tip

Trond Myklebust
2014-01-30T14:17:03Z

On Jan 30, 2014, at 9:08, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:

> I just booted Linus' tip (plus a few other patches to imx-drm and imx
> code), and stumbled into this interesting scenario:
>
> # touch test
> touch: cannot touch `test': Operation not supported
>
> I also tried mkdir and mknod, all result in the same error. Hard and
> symlinks links are creatable.
>
> However, I can chmod existing files and rename them. Files can also be
> deleted, and the combination of this has left me without a /etc/mtab !
>
> The machine is a iMX6 based ARM, running root-nfs, which was mounted via
> ubuntu's initramfs (so not using the kernel's built-in root-nfs.)
>
> /proc/mounts for the root mount gives:
> 192.168.1.123:/var/boot/ci / nfs rw,relatime,vers=3,rsize=65536,wsize=65536,namlen=255,hard,nolock,proto=tcp,port=2049,timeo=7,retrans=10,sec=sys,local_lock=all,addr=192.168.1.123 0 0
>
> CONFIG_NFS_FS=y
> CONFIG_NFS_V2=y
> CONFIG_NFS_V3=y
> CONFIG_NFS_V3_ACL=y
> CONFIG_NFS_V4=y
> # CONFIG_NFS_SWAP is not set
> # CONFIG_NFS_V4_1 is not set
> CONFIG_ROOT_NFS=y
> # CONFIG_NFS_USE_LEGACY_DNS is not set
> CONFIG_NFS_USE_KERNEL_DNS=y
> # CONFIG_NFSD is not set
> CONFIG_LOCKD=y
> CONFIG_LOCKD_V4=y
> CONFIG_NFS_ACL_SUPPORT=y
> CONFIG_NFS_COMMON=y
> CONFIG_SUNRPC=y
> CONFIG_SUNRPC_GSS=y
>
> tcpdumping, I see:
>
> 13:59:51.713523 IP 192.168.1.252.1341245608 > 192.168.1.123.2049: 132 lookup fh Unknown/010007011040840000000000CC238FC8FBA0475D9D9F8356B4C44166CDC38700 "test"
> 13:59:51.714345 IP 192.168.1.123.2049 > 192.168.1.252.1341245608: reply ok 120 lookup ERROR: No such file or directory
> 13:59:51.751303 IP 192.168.1.252.797 > 192.168.1.123.nfs: . ack 3381 win 2625 <nop,nop,timestamp 474136 3431312924>
>
> which is the only NFS packet(s) I see which mention "test".
>
> and stracing touch:
>
> open("test", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK|O_LARGEFILE, 0666) = -1 EOPNOTSUPP (Operation not supported)
> utimensat(AT_FDCWD, "test", NULL, 0) = -1 ENOENT (No such file or directory)
> write(2, "touch: ", 7touch: ) = 7
> write(2, "cannot touch `test'", 19cannot touch `test') = 19
> write(2, ": Operation not supported", 25: Operation not supported) = 25
> write(2, "\n", 1
> ) = 1
>
> I think it's down to this:
>
> commit 013cdf1088d7235da9477a2375654921d9b9ba9f
> Author: Christoph Hellwig <hch@infradead.org>
> Date: Fri Dec 20 05:16:53 2013 -0800
>
> nfs: use generic posix ACL infrastructure for v3 Posix ACLs
>
> This causes a small behaviour change in that we don't bother to set
> ACLs on file creation if the mode bit can express the access permissions
> fully, and thus behaving identical to local filesystems.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
>
> which adds:
>
> + status = posix_acl_create(dir, &sattr->ia_mode, &default_acl, &acl);
> + if (status)
> + goto out;

Right, this should clearly not cause nfs4_proc_create to fail if it returns EOPNOTSUPP.

> into nfs3_proc_create(), but this ends up calling down into nfs3_get_acl(),
> which does this:
>
> if (!nfs_server_capable(inode, NFS_CAP_ACLS))
> return ERR_PTR(-EOPNOTSUPP);

Just for completeness sake: is the server you were running against supposed to support POSIX acls?

--
Trond Myklebust
Linux NFS client maintainer