Re: [PATCH] kernel-modules: handle nfs host fstype properly

[Harald Hoyer <harald-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

This should be fixed by:
https://github.com/dracutdevs/dracut/blob/master/modules.d/95nfs/module-setup.sh#L28

right?

On 15.06.2016 12:01, Xunlei Pang wrote:
> Hi Harald,
> 
> On 2016/06/15 at 17:40, Xunlei Pang wrote:
>> There are scenarios that support fstype target not mounted
>> beforehand, kdump can utilize this feature to avoid imposing
>> severe overload on the shared nfs server when thousands of
>> diskless clients with nfs kdumping boot and trigger kdump
>> initramfs rebuild synchronously.
>>
>> Because target is not mounted beforehand, some of the kernel
>> modules will fail to be installed in hostonly mode. Dracut
>> actually can support this by instmods all "host_fs_types" with
>> hostonly unset in 90kernel-modules/module-setup.sh installkernel().
>>
>> This works properly for most host fstypes(ext[234]/xfs, etc), but
>> that's not the case for nfs.
>>
>> From nfs manpage, we can clearly see:
>> "The fstype field contains "nfs". Use of the "nfs4" fstype in
>> /etc/fstab is deprecated."
>>
>> It means "nfs" specified can be actually mounted as "nfs[3-4]", so
>> for these cases, the current 90kernel-modules implementation only
>> installs ko modules for "nfs"(nfs.ko, etc), lacking nfsv[3-4].ko,
>> so it cannot work properly. In order to address the issue, we should
>> install all the possbile kernel modules for "nfs" fstype:
>> "nfs sunrpc ipv6 nfsv2 nfsv3 nfsv4 nfs_acl nfs_layout_nfsv41_files".
> 
> The list is directly copied from "95nfs/module_setup.sh installkernel()",
> I am not sure if it is enough for all the nfs cases.
> 
> I also tried to use insmods "=fs/nfs" instead, it installed more kernel
> modules compared with the list, for example installed extra:
> 
>   fs/nfs/blocklayout/blocklayoutdriver.ko
>   fs/nfs/flexfilelayout/nfs_layout_flexfiles.ko
>   fs/nfs/objlayout/objlayoutdriver.ko
> 
> 
> I don't know if these kernel modules are necessary, if so I can change
> to use "=fs/nfs" instead.
> 
> Regards,
> Xunlei
> 
>>
>> Additionally, we need a special remapping for "nfs[3-4]" deprecated
>> cases, for example, we should map "nfs4" to "nfsv4.ko" not "nfs4.ko".
>>
>> Signed-off-by: Xunlei Pang <xlpang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>  modules.d/90kernel-modules/module-setup.sh | 20 +++++++++++++++++++-
>>  1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/modules.d/90kernel-modules/module-setup.sh b/modules.d/90kernel-modules/module-setup.sh
>> index 7904c02..1f57ec7 100755
>> --- a/modules.d/90kernel-modules/module-setup.sh
>> +++ b/modules.d/90kernel-modules/module-setup.sh
>> @@ -44,7 +44,25 @@ installkernel() {
>>                  dracut_instmods -o -P ".*/(kernel/fs/nfs|kernel/fs/nfsd|kernel/fs/lockd)/.*" '=fs'
>>              fi
>>          else
>> -            hostonly='' instmods "${host_fs_types[@]}"
>> +            for i in "${host_fs_types[@]}"; do
>> +                if [[ $i = nfs ]]; then
>> +                    # nfs manpage says:
>> +                    # "The fstype field contains "nfs". Use of the "nfs4" fstype in
>> +                    # /etc/fstab is deprecated."
>> +                    #
>> +                    # It means "nfs" can be actually mounted as "nfs4", so for "nfs"
>> +                    # host fstype we better install all the possible kernel modules,
>> +                    # this is useful for kdump "nfs" dumping not mounted beforehand.
>> +                    #
>> +                    # The list is copied from "95nfs/module_setup.sh installkernel()".
>> +                    i="nfs sunrpc ipv6 nfsv2 nfsv3 nfsv4 nfs_acl nfs_layout_nfsv41_files"
>> +                elif [[ $i = nfs[3-4] ]]; then
>> +                    # Deprecated cases, we provide support, but need a name mapping:
>> +                    # For example, should map "nfs4" to use "nfsv4.ko" not "nfs4.ko".
>> +                    i=${i/nfs/nfsv}
>> +                fi
>> +                hostonly='' instmods $i
>> +            done
>>          fi
>>      fi
>>      :
> 
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