Commit ceddc3a5 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds

mm: document is_page_cache_freeable()

Enlighten the reader of this code about what reference count makes a page
cache page freeable.
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent edcf4748
...@@ -286,6 +286,11 @@ static inline int page_mapping_inuse(struct page *page) ...@@ -286,6 +286,11 @@ static inline int page_mapping_inuse(struct page *page)
static inline int is_page_cache_freeable(struct page *page) static inline int is_page_cache_freeable(struct page *page)
{ {
/*
* A freeable page cache page is referenced only by the caller
* that isolated the page, the page cache radix tree and
* optional buffer heads at page->private.
*/
return page_count(page) - page_has_private(page) == 2; return page_count(page) - page_has_private(page) == 2;
} }
......
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