Re: [PATCH v3 2/9] mm: Add 'supports' field to the address_space_operations to list features
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-09-24 20:11:25
Also in:
ceph-devel, linux-fsdevel, linux-mm, linux-nfs, linux-xfs, lkml
On Fri, Sep 24, 2021 at 06:18:14PM +0100, David Howells wrote:
Rather than depending on .direct_IO to point to something to indicate that direct I/O is supported, add a 'supports' bitmask that we can test, since we only need one bit.
Why would you add mapping->aops->supports instead of using one of the free bits in mapping->flags? enum mapping_flags in pagemap.h. It could also be a per-fs flag, or per-sb flag, but it's fewer dereferences at check time if it's in mapping->flags.