Merge patch series "fs/buffer: misc optimizations"

Davidlohr Bueso <dave@stgolabs.net> says:

Four small patches - the first could be sent to Linus for v6.15
considering it is a missing nonblocking lookup conversion in the getblk
slowpath I had missed. The other two patches are small optimizations
found while reading the code, and one rocket science cleanup patch.

* patches from https://lore.kernel.org/20250515173925.147823-1-dave@stgolabs.net:
  fs/buffer: optimize discard_buffer()
  fs/buffer: remove superfluous statements
  fs/buffer: avoid redundant lookup in getblk slowpath
  fs/buffer: use sleeping lookup in __getblk_slowpath()

Link: https://lore.kernel.org/20250515173925.147823-1-dave@stgolabs.net
Signed-off-by: Christian Brauner <brauner@kernel.org>