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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-12-10 16:55:05 +0100
committerMatthew Wilcox (Oracle) <willy@infradead.org>2021-09-27 15:27:30 +0200
commit2f52578f9c64d7d9a96ab81c243cc20804fabf2b (patch)
tree9c1bf5583fb98d2e0027f972bd0a254114278db0 /Documentation/core-api
parentmm/filemap: Add folio_pos() and folio_file_pos() (diff)
downloadlinux-2f52578f9c64d7d9a96ab81c243cc20804fabf2b.tar.xz
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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 'Documentation/core-api')
-rw-r--r--Documentation/core-api/mm-api.rst2
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/core-api/mm-api.rst b/Documentation/core-api/mm-api.rst
index 971149f5d241..395835f9289f 100644
--- a/Documentation/core-api/mm-api.rst
+++ b/Documentation/core-api/mm-api.rst
@@ -101,3 +101,5 @@ More Memory Management Functions
:internal:
.. kernel-doc:: include/linux/page_ref.h
.. kernel-doc:: include/linux/mmzone.h
+.. kernel-doc:: mm/util.c
+ :functions: folio_mapping