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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>
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@ -101,3 +101,5 @@ More Memory Management Functions
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:internal:
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.. kernel-doc:: include/linux/page_ref.h
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.. kernel-doc:: include/linux/mmzone.h
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.. kernel-doc:: mm/util.c
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:functions: folio_mapping
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@ -1755,19 +1755,6 @@ void page_address_init(void);
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extern void *page_rmapping(struct page *page);
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extern struct anon_vma *page_anon_vma(struct page *page);
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extern struct address_space *page_mapping(struct page *page);
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extern struct address_space *__page_file_mapping(struct page *);
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static inline
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struct address_space *page_file_mapping(struct page *page)
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{
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if (unlikely(PageSwapCache(page)))
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return __page_file_mapping(page);
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return page->mapping;
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}
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extern pgoff_t __page_file_index(struct page *page);
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/*
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@ -1782,7 +1769,6 @@ static inline pgoff_t page_index(struct page *page)
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}
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bool page_mapped(struct page *page);
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struct address_space *page_mapping(struct page *page);
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/*
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* Return true only if the page has been allocated with
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@ -162,14 +162,45 @@ static inline void filemap_nr_thps_dec(struct address_space *mapping)
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void release_pages(struct page **pages, int nr);
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struct address_space *page_mapping(struct page *);
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struct address_space *folio_mapping(struct folio *);
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struct address_space *swapcache_mapping(struct folio *);
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/**
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* folio_file_mapping - Find the mapping this folio belongs to.
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* @folio: The folio.
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*
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* For folios which are in the page cache, return the mapping that this
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* page belongs to. Folios in the swap cache return the mapping of the
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* swap file or swap device where the data is stored. This is different
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* from the mapping returned by folio_mapping(). The only reason to
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* use it is if, like NFS, you return 0 from ->activate_swapfile.
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*
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* Do not call this for folios which aren't in the page cache or swap cache.
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*/
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static inline struct address_space *folio_file_mapping(struct folio *folio)
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{
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if (unlikely(folio_test_swapcache(folio)))
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return swapcache_mapping(folio);
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return folio->mapping;
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}
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static inline struct address_space *page_file_mapping(struct page *page)
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{
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return folio_file_mapping(page_folio(page));
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}
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/*
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* For file cache pages, return the address_space, otherwise return NULL
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*/
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static inline struct address_space *page_mapping_file(struct page *page)
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{
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if (unlikely(PageSwapCache(page)))
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struct folio *folio = page_folio(page);
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if (unlikely(folio_test_swapcache(folio)))
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return NULL;
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return page_mapping(page);
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return folio_mapping(folio);
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}
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static inline bool page_cache_add_speculative(struct page *page, int count)
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@ -320,6 +320,12 @@ struct vma_swap_readahead {
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#endif
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};
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static inline swp_entry_t folio_swap_entry(struct folio *folio)
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{
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swp_entry_t entry = { .val = page_private(&folio->page) };
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return entry;
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}
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/* linux/mm/workingset.c */
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void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
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void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
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@ -46,7 +46,7 @@ mmu-$(CONFIG_MMU) += process_vm_access.o
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endif
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obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
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maccess.o page-writeback.o \
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maccess.o page-writeback.o folio-compat.o \
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readahead.o swap.o truncate.o vmscan.o shmem.o \
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util.o mmzone.o vmstat.o backing-dev.o \
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mm_init.o percpu.o slab_common.o \
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13
mm/folio-compat.c
Normal file
13
mm/folio-compat.c
Normal file
@ -0,0 +1,13 @@
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/*
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* Compatibility functions which bloat the callers too much to make inline.
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* All of the callers of these functions should be converted to use folios
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* eventually.
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*/
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#include <linux/pagemap.h>
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struct address_space *page_mapping(struct page *page)
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{
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return folio_mapping(page_folio(page));
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}
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EXPORT_SYMBOL(page_mapping);
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@ -3534,13 +3534,13 @@ struct swap_info_struct *page_swap_info(struct page *page)
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}
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/*
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* out-of-line __page_file_ methods to avoid include hell.
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* out-of-line methods to avoid include hell.
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*/
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struct address_space *__page_file_mapping(struct page *page)
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struct address_space *swapcache_mapping(struct folio *folio)
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{
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return page_swap_info(page)->swap_file->f_mapping;
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return page_swap_info(&folio->page)->swap_file->f_mapping;
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}
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EXPORT_SYMBOL_GPL(__page_file_mapping);
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EXPORT_SYMBOL_GPL(swapcache_mapping);
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pgoff_t __page_file_index(struct page *page)
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{
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30
mm/util.c
30
mm/util.c
@ -705,30 +705,36 @@ struct anon_vma *page_anon_vma(struct page *page)
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return __page_rmapping(page);
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}
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struct address_space *page_mapping(struct page *page)
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/**
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* folio_mapping - Find the mapping where this folio is stored.
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* @folio: The folio.
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*
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* For folios which are in the page cache, return the mapping that this
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* page belongs to. Folios in the swap cache return the swap mapping
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* this page is stored in (which is different from the mapping for the
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* swap file or swap device where the data is stored).
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*
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* You can call this for folios which aren't in the swap cache or page
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* cache and it will return NULL.
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*/
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struct address_space *folio_mapping(struct folio *folio)
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{
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struct address_space *mapping;
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page = compound_head(page);
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/* This happens if someone calls flush_dcache_page on slab page */
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if (unlikely(PageSlab(page)))
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if (unlikely(folio_test_slab(folio)))
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return NULL;
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if (unlikely(PageSwapCache(page))) {
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swp_entry_t entry;
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if (unlikely(folio_test_swapcache(folio)))
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return swap_address_space(folio_swap_entry(folio));
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entry.val = page_private(page);
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return swap_address_space(entry);
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}
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mapping = page->mapping;
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mapping = folio->mapping;
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if ((unsigned long)mapping & PAGE_MAPPING_ANON)
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return NULL;
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return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
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}
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EXPORT_SYMBOL(page_mapping);
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EXPORT_SYMBOL(folio_mapping);
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/* Slow path of page_mapcount() for compound pages */
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int __page_mapcount(struct page *page)
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