On Sat, Nov 14, 2020 at 10:50:39AM -0800, Andrew Morton wrote: > But really, shmem_mapping() isn't worth an out-of-line call from any > callsite - it would be best to make it inlined everywhere. > > - make shmem_aops global > - declare shmem_aops in shmem_fs.h > - export shmem_aops to modules for drivers/dma-buf/udmabuf.c > - include linux/fs.h in shmem_fs.h for address_space_operations (we already > include fs.h via swap.h, but we shouldn't depend on that) > - make shmem_mapping() a static inline in shmem_fs.h.
... or use an AS_ bit to make shmem_mapping() global inline without exposing the shmem_aops symbol. We're not short of AS_ bits, and it's probably even cheaper than a pointer comparison. A really good changelog would explain why we need shmem_mapping() everywhere that we currently use it. It's not immediately obvious why so many places need to know.
