Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> wrote: > These are the folio equivalent of page_mapping() and page_file_mapping(). > Add an out-of-line page_mapping() wrapper around folio_mapping() > in order to prevent the page_folio() call from bloating every caller > of page_mapping(). Adjust page_file_mapping() and page_mapping_file() Confusingly named, but not the fault of this patch. > to use folios internally. Rename __page_file_mapping() to > swapcache_mapping() and change it to take a folio. > > This ends up saving 122 bytes of text overall. folio_mapping() is > 45 bytes shorter than page_mapping() was, but the new page_mapping() > wrapper is 30 bytes. The major reduction is a few bytes less in dozens > of nfs functions (which call page_file_mapping()). Most of these appear > to be a slight change in gcc's register allocation decisions, which allow: > > 48 8b 56 08 mov 0x8(%rsi),%rdx > 48 8d 42 ff lea -0x1(%rdx),%rax > 83 e2 01 and $0x1,%edx > 48 0f 44 c6 cmove %rsi,%rax > > to become: > > 48 8b 46 08 mov 0x8(%rsi),%rax > 48 8d 78 ff lea -0x1(%rax),%rdi > a8 01 test $0x1,%al > 48 0f 44 fe cmove %rsi,%rdi > > for a reduction of a single byte. Once the NFS client is converted to > use folios, this entire sequence will disappear. > > Also add folio_mapping() documentation. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Acked-by: Jeff Layton <jlayton@xxxxxxxxxx> > Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx> Reviewed-by: David Howells <dhowells@xxxxxxxxxx>
