fs: reset read-only fsflags together with xflags

fs: reset read-only fsflags together with xflags

While setting file attributes, the read-only flags are reset
for ->xflags, but not for ->flags if flag is shared between both. This
is fine for now as all read-only xflags don't overlap with flags.
However, for any read-only shared flag this will create inconsistency
between xflags and flags. The non-shared flag will be reset in
vfs_fileattr_set() to the current value, but shared one is past further
to ->fileattr_set.

Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://patch.msgid.link/20260121193645.3611716-1-aalbersh@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>