| Message ID | 20210715033704.692967-17-willy@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Memory folios | expand |
On Thu, Jul 15, 2021 at 04:35:02AM +0100, Matthew Wilcox (Oracle) 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() > 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> > --- > Documentation/core-api/mm-api.rst | 2 ++ > include/linux/mm.h | 14 ------------- > include/linux/pagemap.h | 35 +++++++++++++++++++++++++++++-- > include/linux/swap.h | 6 ++++++ > mm/Makefile | 2 +- > mm/folio-compat.c | 13 ++++++++++++ > mm/swapfile.c | 8 +++---- > mm/util.c | 30 +++++++++++++++----------- > 8 files changed, 77 insertions(+), 33 deletions(-) > create mode 100644 mm/folio-compat.c > > diff --git a/Documentation/core-api/mm-api.rst b/Documentation/core-api/mm-api.rst > index 5c459ee2acce..dcce6605947a 100644 > --- a/Documentation/core-api/mm-api.rst > +++ b/Documentation/core-api/mm-api.rst > @@ -100,3 +100,5 @@ 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 > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 788fbc4cde0c..9d28f5b2e983 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1753,19 +1753,6 @@ void page_address_init(void); > > extern void *page_rmapping(struct page *page); > extern struct anon_vma *page_anon_vma(struct page *page); > -extern struct address_space *page_mapping(struct page *page); > - > -extern struct address_space *__page_file_mapping(struct page *); > - > -static inline > -struct address_space *page_file_mapping(struct page *page) > -{ > - if (unlikely(PageSwapCache(page))) > - return __page_file_mapping(page); > - > - return page->mapping; > -} > - > extern pgoff_t __page_file_index(struct page *page); > > /* > @@ -1780,7 +1767,6 @@ static inline pgoff_t page_index(struct page *page) > } > > bool page_mapped(struct page *page); > -struct address_space *page_mapping(struct page *page); > > /* > * Return true only if the page has been allocated with > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index aa71fa82d6be..a0925a89ba11 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -162,14 +162,45 @@ static inline void filemap_nr_thps_dec(struct address_space *mapping) > > void release_pages(struct page **pages, int nr); > > +struct address_space *page_mapping(struct page *); > +struct address_space *folio_mapping(struct folio *); > +struct address_space *swapcache_mapping(struct folio *); > + > +/** > + * folio_file_mapping - Find the mapping this folio belongs to. > + * @folio: The folio. > + * > + * For folios which are in the page cache, return the mapping that this > + * page belongs to. Folios in the swap cache return the mapping of the > + * swap file or swap device where the data is stored. This is different > + * from the mapping returned by folio_mapping(). The only reason to > + * use it is if, like NFS, you return 0 from ->activate_swapfile. > + * > + * Do not call this for folios which aren't in the page cache or swap cache. Missing return value description. > + */ > +static inline struct address_space *folio_file_mapping(struct folio *folio) > +{ > + if (unlikely(folio_test_swapcache(folio))) > + return swapcache_mapping(folio); > + > + return folio->mapping; > +} > + > +static inline struct address_space *page_file_mapping(struct page *page) > +{ > + return folio_file_mapping(page_folio(page)); > +} > + [ snip ] > diff --git a/mm/util.c b/mm/util.c > index 9043d03750a7..1cde6218d6d1 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -686,30 +686,36 @@ struct anon_vma *page_anon_vma(struct page *page) > return __page_rmapping(page); > } > > -struct address_space *page_mapping(struct page *page) > +/** > + * folio_mapping - Find the mapping where this folio is stored. > + * @folio: The folio. > + * > + * For folios which are in the page cache, return the mapping that this > + * page belongs to. Folios in the swap cache return the swap mapping > + * this page is stored in (which is different from the mapping for the > + * swap file or swap device where the data is stored). > + * > + * You can call this for folios which aren't in the swap cache or page > + * cache and it will return NULL. > + */ Missing return value description. > +struct address_space *folio_mapping(struct folio *folio) > { > struct address_space *mapping; > > - page = compound_head(page); > - > /* This happens if someone calls flush_dcache_page on slab page */ > - if (unlikely(PageSlab(page))) > + if (unlikely(folio_test_slab(folio))) > return NULL; > > - if (unlikely(PageSwapCache(page))) { > - swp_entry_t entry; > - > - entry.val = page_private(page); > - return swap_address_space(entry); > - } > + if (unlikely(folio_test_swapcache(folio))) > + return swap_address_space(folio_swap_entry(folio)); > > - mapping = page->mapping; > + mapping = folio->mapping; > if ((unsigned long)mapping & PAGE_MAPPING_ANON) > return NULL; > > return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS); > } > -EXPORT_SYMBOL(page_mapping); > +EXPORT_SYMBOL(folio_mapping); > > /* Slow path of page_mapcount() for compound pages */ > int __page_mapcount(struct page *page) > -- > 2.30.2 > >
diff --git a/Documentation/core-api/mm-api.rst b/Documentation/core-api/mm-api.rst index 5c459ee2acce..dcce6605947a 100644 --- a/Documentation/core-api/mm-api.rst +++ b/Documentation/core-api/mm-api.rst @@ -100,3 +100,5 @@ 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 diff --git a/include/linux/mm.h b/include/linux/mm.h index 788fbc4cde0c..9d28f5b2e983 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1753,19 +1753,6 @@ void page_address_init(void); extern void *page_rmapping(struct page *page); extern struct anon_vma *page_anon_vma(struct page *page); -extern struct address_space *page_mapping(struct page *page); - -extern struct address_space *__page_file_mapping(struct page *); - -static inline -struct address_space *page_file_mapping(struct page *page) -{ - if (unlikely(PageSwapCache(page))) - return __page_file_mapping(page); - - return page->mapping; -} - extern pgoff_t __page_file_index(struct page *page); /* @@ -1780,7 +1767,6 @@ static inline pgoff_t page_index(struct page *page) } bool page_mapped(struct page *page); -struct address_space *page_mapping(struct page *page); /* * Return true only if the page has been allocated with diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index aa71fa82d6be..a0925a89ba11 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -162,14 +162,45 @@ static inline void filemap_nr_thps_dec(struct address_space *mapping) void release_pages(struct page **pages, int nr); +struct address_space *page_mapping(struct page *); +struct address_space *folio_mapping(struct folio *); +struct address_space *swapcache_mapping(struct folio *); + +/** + * folio_file_mapping - Find the mapping this folio belongs to. + * @folio: The folio. + * + * For folios which are in the page cache, return the mapping that this + * page belongs to. Folios in the swap cache return the mapping of the + * swap file or swap device where the data is stored. This is different + * from the mapping returned by folio_mapping(). The only reason to + * use it is if, like NFS, you return 0 from ->activate_swapfile. + * + * Do not call this for folios which aren't in the page cache or swap cache. + */ +static inline struct address_space *folio_file_mapping(struct folio *folio) +{ + if (unlikely(folio_test_swapcache(folio))) + return swapcache_mapping(folio); + + return folio->mapping; +} + +static inline struct address_space *page_file_mapping(struct page *page) +{ + return folio_file_mapping(page_folio(page)); +} + /* * For file cache pages, return the address_space, otherwise return NULL */ static inline struct address_space *page_mapping_file(struct page *page) { - if (unlikely(PageSwapCache(page))) + struct folio *folio = page_folio(page); + + if (unlikely(folio_test_swapcache(folio))) return NULL; - return page_mapping(page); + return folio_mapping(folio); } static inline bool page_cache_add_speculative(struct page *page, int count) diff --git a/include/linux/swap.h b/include/linux/swap.h index 6f5a43251593..3d3d85354026 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -320,6 +320,12 @@ struct vma_swap_readahead { #endif }; +static inline swp_entry_t folio_swap_entry(struct folio *folio) +{ + swp_entry_t entry = { .val = page_private(&folio->page) }; + return entry; +} + /* linux/mm/workingset.c */ void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages); void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg); diff --git a/mm/Makefile b/mm/Makefile index e3436741d539..d7488bcbbb2b 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 \ diff --git a/mm/folio-compat.c b/mm/folio-compat.c new file mode 100644 index 000000000000..5e107aa30a62 --- /dev/null +++ b/mm/folio-compat.c @@ -0,0 +1,13 @@ +/* + * Compatibility functions which bloat the callers too much to make inline. + * All of the callers of these functions should be converted to use folios + * eventually. + */ + +#include <linux/pagemap.h> + +struct address_space *page_mapping(struct page *page) +{ + return folio_mapping(page_folio(page)); +} +EXPORT_SYMBOL(page_mapping); diff --git a/mm/swapfile.c b/mm/swapfile.c index 1e07d1c776f2..3a6c094310da 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3528,13 +3528,13 @@ struct swap_info_struct *page_swap_info(struct page *page) } /* - * out-of-line __page_file_ methods to avoid include hell. + * out-of-line methods to avoid include hell. */ -struct address_space *__page_file_mapping(struct page *page) +struct address_space *swapcache_mapping(struct folio *folio) { - return page_swap_info(page)->swap_file->f_mapping; + return page_swap_info(&folio->page)->swap_file->f_mapping; } -EXPORT_SYMBOL_GPL(__page_file_mapping); +EXPORT_SYMBOL_GPL(swapcache_mapping); pgoff_t __page_file_index(struct page *page) { diff --git a/mm/util.c b/mm/util.c index 9043d03750a7..1cde6218d6d1 100644 --- a/mm/util.c +++ b/mm/util.c @@ -686,30 +686,36 @@ struct anon_vma *page_anon_vma(struct page *page) return __page_rmapping(page); } -struct address_space *page_mapping(struct page *page) +/** + * folio_mapping - Find the mapping where this folio is stored. + * @folio: The folio. + * + * For folios which are in the page cache, return the mapping that this + * page belongs to. Folios in the swap cache return the swap mapping + * this page is stored in (which is different from the mapping for the + * swap file or swap device where the data is stored). + * + * You can call this for folios which aren't in the swap cache or page + * cache and it will return NULL. + */ +struct address_space *folio_mapping(struct folio *folio) { struct address_space *mapping; - page = compound_head(page); - /* This happens if someone calls flush_dcache_page on slab page */ - if (unlikely(PageSlab(page))) + if (unlikely(folio_test_slab(folio))) return NULL; - if (unlikely(PageSwapCache(page))) { - swp_entry_t entry; - - entry.val = page_private(page); - return swap_address_space(entry); - } + if (unlikely(folio_test_swapcache(folio))) + return swap_address_space(folio_swap_entry(folio)); - mapping = page->mapping; + mapping = folio->mapping; if ((unsigned long)mapping & PAGE_MAPPING_ANON) return NULL; return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS); } -EXPORT_SYMBOL(page_mapping); +EXPORT_SYMBOL(folio_mapping); /* Slow path of page_mapcount() for compound pages */ int __page_mapcount(struct page *page)