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author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-12-10 10:55:05 -0500 |
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committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2021-09-27 09:27:30 -0400 |
commit | 2f52578f9c64d7d9a96ab81c243cc20804fabf2b (patch) | |
tree | 9c1bf5583fb98d2e0027f972bd0a254114278db0 /mm/Makefile | |
parent | 352b47a6984470954e1e262126b1da5312c40b09 (diff) | |
download | lwn-2f52578f9c64d7d9a96ab81c243cc20804fabf2b.tar.gz lwn-2f52578f9c64d7d9a96ab81c243cc20804fabf2b.zip |
mm/util: Add folio_mapping() and folio_file_mapping()
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()
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 $0x1,%al
48 0f 44 fe cmove %rsi,%rdi
for a reduction of a single byte. Once the NFS client is converted to
use folios, this entire sequence will disappear.
Also add folio_mapping() documentation.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'mm/Makefile')
-rw-r--r-- | mm/Makefile | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/Makefile b/mm/Makefile index fc60a40ce954..d6c0042e3aa0 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -46,7 +46,7 @@ mmu-$(CONFIG_MMU) += process_vm_access.o endif obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ - maccess.o page-writeback.o \ + maccess.o page-writeback.o folio-compat.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ util.o mmzone.o vmstat.o backing-dev.o \ mm_init.o percpu.o slab_common.o \ |