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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-12-10 18:55:05 +0300
committerMatthew Wilcox (Oracle) <willy@infradead.org>2021-09-27 16:27:30 +0300
commit2f52578f9c64d7d9a96ab81c243cc20804fabf2b (patch)
tree9c1bf5583fb98d2e0027f972bd0a254114278db0
parent352b47a6984470954e1e262126b1da5312c40b09 (diff)
downloadlinux-2f52578f9c64d7d9a96ab81c243cc20804fabf2b.tar.xz
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>
-rw-r--r--Documentation/core-api/mm-api.rst2
-rw-r--r--include/linux/mm.h14
-rw-r--r--include/linux/pagemap.h35
-rw-r--r--include/linux/swap.h6
-rw-r--r--mm/Makefile2
-rw-r--r--mm/folio-compat.c13
-rw-r--r--mm/swapfile.c8
-rw-r--r--mm/util.c30
8 files changed, 77 insertions, 33 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
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 63685d953ce0..bc5c38e1f780 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1755,19 +1755,6 @@ 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);
/*
@@ -1782,7 +1769,6 @@ 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 3354117a1dae..0ca96a40fabe 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 ba52f3a3478e..85607c6c0cba 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 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 \
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 22d10f713848..e3dcaeecc50f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3534,13 +3534,13 @@ 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 bacabe446906..6c1fe9bee30a 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -705,30 +705,36 @@ 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)