[NFS] [PATCH] knfsd : export : Fix bug of svc_export_parse()

[Wei Yongjun]

  I  have test some of the export entry's type: file, dir, symlink, 
block device, char device, socket , fifo,  and dir which is a mount 
entry used your patch, this patch can resolve all of this problem.
  Thanks

Neil Brown wrote:
> On Tuesday March 27, yjwei at cn.fujitsu.com wrote:
>   
>> Nobody replied yet, but I think this is really a BUG of exportfs.
>> exportfs command does not check so strictly, so maybe some unreasonable
>> fh.key can be add to /proc/net/rpc/nfsd.fh/channel, but used this key to
>> find fh.handle, this always be fail and still retry.
>>
>> It's this correct?
>>     
>
> Sorry for not replying earlier.
>
> Yes, you have identified a real problem, but I'm not sure I agree with
> the first.
>
> If someone (mountd) tried to tell the kernel to export "/dev/null", it
> fails with an error (-ENODIR), and I think this is correct.
>
> Mountd should respond properly to this error, which it doesn't at the
> moment.
> When the request comes via the MOUNT protocol from an NFSv2 or NFSv3
> client, mountd will fail the mount as it should.
> However when the request comes from the kernel due to an NFSv4
> request, the error is just ignored.  In that case we really should be
> telling the kernel that the filehandle is not valid by writing out an
> appropriate message.
>
>
> Maybe something like this in nfs-utils.
> What do you think?
>
> Signed-off-by: Neil Brown <neilb at suse.de>
>
> ### Diffstat output
>  ./utils/mountd/cache.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff .prev/utils/mountd/cache.c ./utils/mountd/cache.c
> --- .prev/utils/mountd/cache.c	2007-03-27 12:11:52.000000000 +1000
> +++ ./utils/mountd/cache.c	2007-03-27 12:13:40.000000000 +1000
> @@ -469,7 +469,8 @@ void nfsd_fh(FILE *f)
>  	}
>  
>  	if (found)
> -		cache_export_ent(dom, found, found_path);
> +		if (cache_export_ent(dom, found, found_path) < 0)
> +			found = 0;
>  
>  	qword_print(f, dom);
>  	qword_printint(f, fsidtype);
> @@ -619,8 +620,10 @@ void nfsd_export(FILE *f)
>  	}
>  
>  	if (found) {
> -		dump_to_cache(f, dom, path, &found->m_export);
> -		mountlist_add(dom, path);
> +		if (dump_to_cache(f, dom, path, &found->m_export) < 0)
> +			dump_to_cache(f, dom, path, NULL);
> +		else
> +			mountlist_add(dom, path);
>  	} else {
>  		dump_to_cache(f, dom, path, NULL);
>  	}
>