fs: add i_user_ns() helper

Since we'll be passing the filesystem's idmapping in even more places in
the following patches and we do already dereference struct inode to get
to the filesystem's idmapping multiple times add a tiny helper.

Link: https://lore.kernel.org/r/[email protected] (v1)
Link: https://lore.kernel.org/r/[email protected] (v2)
Link: https://lore.kernel.org/r/[email protected]
Cc: Seth Forshee <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
CC: [email protected]
Reviewed-by: Amir Goldstein <[email protected]>
Reviewed-by: Seth Forshee <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

0 files changed, 0 insertions, 0 deletions