linux-kernel - Re: [RFC PATCH 0/3] Rename "cifs" module to "smbfs"

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Date:   Thu, 4 Aug 2022 21:23:46 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Jeff Layton <jlayton@...nel.org>
Cc:     Enzo Matsumiya <ematsumiya@...e.de>, Tom Talpey <tom@...pey.com>,
        linux-cifs@...r.kernel.org, smfrench@...il.com, pc@....nz,
        ronniesahlberg@...il.com, nspmangalore@...il.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        samba-technical@...ts.samba.org, pshilovsky@...ba.org
Subject: Re: [RFC PATCH 0/3] Rename "cifs" module to "smbfs"

On Thu, Aug 04, 2022 at 03:03:23PM -0400, Jeff Layton wrote:
> On Tue, 2022-08-02 at 22:56 -0300, Enzo Matsumiya wrote:
> > On 08/02, Tom Talpey wrote:
> > > The initial goal is to modularize the SMB1 code, so it can be completely
> > > removed from a running system. The extensive refactoring logically leads
> > > to this directory renaming, but renaming is basically a side effect.
> > > 
> 
> This is a great technical goal. Splitting up cifs.ko into smaller
> modules would be great, in addition to being able to turn off smb1
> support.

I don't know the CIFS module that well.  How do you see it being split
up?  It's #4 in the list of filesystems:

$ size /lib/modules/5.18.0-3-amd64/kernel/fs/*/*.ko |sort -n |tail
 369020	  28460	    132	 397612	  6112c	/lib/modules/5.18.0-3-amd64/kernel/fs/ubifs/ubifs.ko
 395793	  50398	    960	 447151	  6d2af	/lib/modules/5.18.0-3-amd64/kernel/fs/ceph/ceph.ko
 477909	  58883	  10512	 547304	  859e8	/lib/modules/5.18.0-3-amd64/kernel/fs/nfsd/nfsd.ko
 609260	  84848	    640	 694748	  a99dc	/lib/modules/5.18.0-3-amd64/kernel/fs/f2fs/f2fs.ko
 622638	 252078	   1008	 875724	  d5ccc	/lib/modules/5.18.0-3-amd64/kernel/fs/nfs/nfsv4.ko
 717343	 111314	   1176	 829833	  ca989	/lib/modules/5.18.0-3-amd64/kernel/fs/ext4/ext4.ko
 884247	 206051	    504	1090802	 10a4f2	/lib/modules/5.18.0-3-amd64/kernel/fs/cifs/cifs.ko
 890155	 159520	    240	1049915	 10053b	/lib/modules/5.18.0-3-amd64/kernel/fs/ocfs2/ocfs2.ko
1193834	 274148	    456	1468438	 166816	/lib/modules/5.18.0-3-amd64/kernel/fs/xfs/xfs.ko
1393088	 126501	  15072	1534661	 176ac5	/lib/modules/5.18.0-3-amd64/kernel/fs/btrfs/btrfs.ko

... but if you look at how NFS is split up:

 311322	  76200	    392	 387914	  5eb4a	/lib/modules/5.18.0-3-amd64/kernel/fs/nfs/nfs.ko
  25157	   1100	     72	  26329	   66d9	/lib/modules/5.18.0-3-amd64/kernel/fs/nfs/nfsv2.ko
  49332	   1544	    120	  50996	   c734	/lib/modules/5.18.0-3-amd64/kernel/fs/nfs/nfsv3.ko
 622638	 252078	   1008	 875724	  d5ccc	/lib/modules/5.18.0-3-amd64/kernel/fs/nfs/nfsv4.ko

you can save a lot of RAM if you don't need NFSv4 (then there's also
nfs_common, 408kB of sunrpc.ko, etc, etc).