Re: [PATCH 4/8] vfs: Fold casefolding into vfs

[Gao Xiang <gaoxiang25@huawei.com>]

On Mon, Dec 02, 2019 at 09:10:45PM -0800, Daniel Rosenberg wrote:
> Ext4 and F2fs are both using casefolding, and they, along with any other
> filesystem that adds the feature, will be using identical dentry_ops.
> Additionally, those dentry ops interfere with the dentry_ops required
> for fscrypt once we add support for casefolding and encryption.
> Moving this into the vfs removes code duplication as well as the
> complication with encryption.
> 
> Currently this is pretty close to just moving the existing f2fs/ext4
> code up a level into the vfs, although there is a lot of room for
> improvement now.
> 
> Signed-off-by: Daniel Rosenberg <drosen@google.com>

I'm afraid that such vfs modification is unneeded.

Just a quick glance it seems just can be replaced by introducing some
.d_cmp, .d_hash helpers (or with little modification) and most non-Android
emulated storage files are not casefolded (even in Android).

"those dentry ops interfere with the dentry_ops required for fscrypt",
I don't think it's a real diffculty and it could be done with some
better approach instead.

Thanks,
Gao Xiang