From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hui Su <sh_def@163.com>,
hughd@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, pankaj.gupta.linux@gmail.com,
lkp@intel.com
Subject: Re: [PATCH v2] mm/shmem.c: make shmem_mapping() inline
Date: Sat, 14 Nov 2020 19:11:58 +0000 [thread overview]
Message-ID: <20201114191158.GN17076@casper.infradead.org> (raw)
In-Reply-To: <20201114105039.4d44e3036e22e10c9a70912c@linux-foundation.org>
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.
next prev parent reply other threads:[~2020-11-14 19:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-14 5:51 [PATCH v2] mm/shmem.c: make shmem_mapping() inline Hui Su
2020-11-14 18:50 ` Andrew Morton
2020-11-14 19:11 ` Matthew Wilcox [this message]
2020-11-15 16:19 ` Hui Su
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