[PATCH v4 1/3] libfs: Add generic function for setting dentry_ops

[Gabriel Krisman Bertazi]

Daniel Rosenberg <drosen at google.com> writes:

> This adds a function to set dentry operations at lookup time that will
> work for both encrypted filenames and casefolded filenames.
>
> A filesystem that supports both features simultaneously can use this
> function during lookup preparations to set up its dentry operations once
> fscrypt no longer does that itself.
>
> Currently the casefolding dentry operation are always set if the
> filesystem defines an encoding because the features is toggleable on
> empty directories. Unlike in the encryption case, the dentry operations
> used come from the parent. Since we don't know what set of functions
> we'll eventually need, and cannot change them later, we enable the
> casefolding operations if the filesystem supports them at all.
>
> By splitting out the various cases, we support as few dentry operations
> as we can get away with, maximizing compatibility with overlayfs, which
> will not function if a filesystem supports certain dentry_operations.
>
> Signed-off-by: Daniel Rosenberg <drosen at google.com>
> Reviewed-by: Eric Biggers <ebiggers at google.com>

Reviewed-by: Gabriel Krisman Bertazi <krisman at collabora.com>

-- 
Gabriel Krisman Bertazi