Switching to iterate_shared

[Casey Schaufler]

On 8/16/2022 12:11 PM, Matthew Wilcox wrote:
> On Tue, Aug 16, 2022 at 11:58:36AM -0700, Linus Torvalds wrote:
>> That said, our filldir code is still confusing as hell. And I would
>> really like to see that "shared vs non-shared" iterator thing go away,
>> with everybody using the shared one - and filesystems that can't deal
>> with it using their own lock.
>>
>> But that's a completely independent wart in our complicated filldir saga.
>>
>> But if somebody were to look at that iterate-vs-iterate_shared, that
>> would be lovely. A quick grep shows that we don't have *that* many of
>> the non-shared cases left:
>>
>>       git grep '\.iterate\>.*='
>>
>> seems to imply that converting them to a "use my own load" wouldn't be
>> _too_ bad.
>>
>> And some of them might actually be perfectly ok with the shared
>> semantics (ie inode->i_rwsem held just for reading) and they just were
>> never converted originally.
> What's depressing is that some of these are newly added.  It'd be
> great if we could attach something _like_ __deprecated to things
> that checkpatch could pick up on.
>
> fs/adfs/dir_f.c:        .iterate        = adfs_f_iterate,
> fs/adfs/dir_fplus.c:    .iterate        = adfs_fplus_iterate,
>
> ADFS is read-only, so must be safe?
>
> fs/ceph/dir.c:  .iterate = ceph_readdir,
> fs/ceph/dir.c:  .iterate = ceph_readdir,
>
> At least CEPH has active maintainers, cc'd
>
> fs/coda/dir.c:  .iterate        = coda_readdir,
>
> Would anyone notice if we broke CODA?  Maintainers cc'd anyway.
>
> fs/exfat/dir.c: .iterate        = exfat_iterate,
>
> Exfat is a new addition, but has active maintainers.
>
> fs/jfs/namei.c: .iterate        = jfs_readdir,
>
> Maintainer cc'd
>
> fs/ntfs/dir.c:  .iterate        = ntfs_readdir,         /* Read directory contents. */
>
> Maybe we can get rid of ntfs soon.
>
> fs/ocfs2/file.c:        .iterate        = ocfs2_readdir,
> fs/ocfs2/file.c:        .iterate        = ocfs2_readdir,
>
> maintainers cc'd
>
> fs/orangefs/dir.c:      .iterate = orangefs_dir_iterate,
>
> New; maintainer cc'd
>
> fs/overlayfs/readdir.c: .iterate        = ovl_iterate,
>
> Active maintainer, cc'd
>
> fs/proc/base.c: .iterate        = proc_##LSM##_attr_dir_iterate, \
>
> Hmm.  We need both SMACK and Apparmor to agree to this ... cc's added.

Smack passes all tests and seems perfectly content with the change.
I can't say that the tests stress this interface.

>
> fs/vboxsf/dir.c:        .iterate = vboxsf_dir_iterate,
>
> Also newly added.  Maintainer cc'd.