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mm: Add folio reference count functions

Browse source 
These functions mirror their page reference counterparts.  Also add
the kernel-doc to the mm-api and correct the return type of
page_ref_add_unless() to bool.  No change to generated code.

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>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-03-31 10:39:55 -04:00
parent 9e9edb2094
commit c24016ac3a
2 changed files with 88 additions and 1 deletions
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1
Documentation/core-api/mm-api.rst
View file

@ -98,4 +98,5 @@ More Memory Management Functions
.. kernel-doc:: include/linux/page-flags.h
.. kernel-doc:: include/linux/mm.h
:internal:
.. kernel-doc:: include/linux/page_ref.h
.. kernel-doc:: include/linux/mmzone.h

88
include/linux/page_ref.h
View file

@ -67,9 +67,31 @@ static inline int page_ref_count(const struct page *page)
return atomic_read(&page->_refcount);
}
/**
* folio_ref_count - The reference count on this folio.
* @folio: The folio.
*
* The refcount is usually incremented by calls to folio_get() and
* decremented by calls to folio_put(). Some typical users of the
* folio refcount:
*
* - Each reference from a page table
* - The page cache
* - Filesystem private data
* - The LRU list
* - Pipes
* - Direct IO which references this page in the process address space
*
* Return: The number of references to this folio.
*/
static inline int folio_ref_count(const struct folio *folio)
{
return page_ref_count(&folio->page);
}
static inline int page_count(const struct page *page)
{
return atomic_read(&compound_head(page)->_refcount);
return folio_ref_count(page_folio(page));
}
static inline void set_page_count(struct page *page, int v)
@ -79,6 +101,11 @@ static inline void set_page_count(struct page *page, int v)
__page_ref_set(page, v);
}
static inline void folio_set_count(struct folio *folio, int v)
{
set_page_count(&folio->page, v);
}
/*
* Setup the page count before being freed into the page allocator for
* the first time (boot or memory hotplug)
@ -95,6 +122,11 @@ static inline void page_ref_add(struct page *page, int nr)
__page_ref_mod(page, nr);
}
static inline void folio_ref_add(struct folio *folio, int nr)
{
page_ref_add(&folio->page, nr);
}
static inline void page_ref_sub(struct page *page, int nr)
{
atomic_sub(nr, &page->_refcount);
@ -102,6 +134,11 @@ static inline void page_ref_sub(struct page *page, int nr)
__page_ref_mod(page, -nr);
}
static inline void folio_ref_sub(struct folio *folio, int nr)
{
page_ref_sub(&folio->page, nr);
}
static inline int page_ref_sub_return(struct page *page, int nr)
{
int ret = atomic_sub_return(nr, &page->_refcount);
@ -111,6 +148,11 @@ static inline int page_ref_sub_return(struct page *page, int nr)
return ret;
}
static inline int folio_ref_sub_return(struct folio *folio, int nr)
{
return page_ref_sub_return(&folio->page, nr);
}
static inline void page_ref_inc(struct page *page)
{
atomic_inc(&page->_refcount);
@ -118,6 +160,11 @@ static inline void page_ref_inc(struct page *page)
__page_ref_mod(page, 1);
}
static inline void folio_ref_inc(struct folio *folio)
{
page_ref_inc(&folio->page);
}
static inline void page_ref_dec(struct page *page)
{
atomic_dec(&page->_refcount);
@ -125,6 +172,11 @@ static inline void page_ref_dec(struct page *page)
__page_ref_mod(page, -1);
}
static inline void folio_ref_dec(struct folio *folio)
{
page_ref_dec(&folio->page);
}
static inline int page_ref_sub_and_test(struct page *page, int nr)
{
int ret = atomic_sub_and_test(nr, &page->_refcount);
@ -134,6 +186,11 @@ static inline int page_ref_sub_and_test(struct page *page, int nr)
return ret;
}
static inline int folio_ref_sub_and_test(struct folio *folio, int nr)
{
return page_ref_sub_and_test(&folio->page, nr);
}
static inline int page_ref_inc_return(struct page *page)
{
int ret = atomic_inc_return(&page->_refcount);
@ -143,6 +200,11 @@ static inline int page_ref_inc_return(struct page *page)
return ret;
}
static inline int folio_ref_inc_return(struct folio *folio)
{
return page_ref_inc_return(&folio->page);
}
static inline int page_ref_dec_and_test(struct page *page)
{
int ret = atomic_dec_and_test(&page->_refcount);
@ -152,6 +214,11 @@ static inline int page_ref_dec_and_test(struct page *page)
return ret;
}
static inline int folio_ref_dec_and_test(struct folio *folio)
{
return page_ref_dec_and_test(&folio->page);
}
static inline int page_ref_dec_return(struct page *page)
{
int ret = atomic_dec_return(&page->_refcount);
@ -161,6 +228,11 @@ static inline int page_ref_dec_return(struct page *page)
return ret;
}
static inline int folio_ref_dec_return(struct folio *folio)
{
return page_ref_dec_return(&folio->page);
}
static inline bool page_ref_add_unless(struct page *page, int nr, int u)
{
bool ret = atomic_add_unless(&page->_refcount, nr, u);
@ -170,6 +242,11 @@ static inline bool page_ref_add_unless(struct page *page, int nr, int u)
return ret;
}
static inline bool folio_ref_add_unless(struct folio *folio, int nr, int u)
{
return page_ref_add_unless(&folio->page, nr, u);
}
static inline int page_ref_freeze(struct page *page, int count)
{
int ret = likely(atomic_cmpxchg(&page->_refcount, count, 0) == count);
@ -179,6 +256,11 @@ static inline int page_ref_freeze(struct page *page, int count)
return ret;
}
static inline int folio_ref_freeze(struct folio *folio, int count)
{
return page_ref_freeze(&folio->page, count);
}
static inline void page_ref_unfreeze(struct page *page, int count)
{
VM_BUG_ON_PAGE(page_count(page) != 0, page);
@ -189,4 +271,8 @@ static inline void page_ref_unfreeze(struct page *page, int count)
__page_ref_unfreeze(page, count);
}
static inline void folio_ref_unfreeze(struct folio *folio, int count)
{
page_ref_unfreeze(&folio->page, count);
}
#endif