Commit a8cf7f27 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds

mm: add find_lock_head

Add a new FGP_HEAD flag which avoids calling find_subpage() and add a
convenience wrapper for it.
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-9-willy@infradead.orgSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 63ec1973
...@@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping, ...@@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_NOFS 0x00000010 #define FGP_NOFS 0x00000010
#define FGP_NOWAIT 0x00000020 #define FGP_NOWAIT 0x00000020
#define FGP_FOR_MMAP 0x00000040 #define FGP_FOR_MMAP 0x00000040
#define FGP_HEAD 0x00000080
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask); int fgp_flags, gfp_t cache_gfp_mask);
...@@ -310,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping, ...@@ -310,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
* @mapping: the address_space to search * @mapping: the address_space to search
* @offset: the page index * @offset: the page index
* *
* Looks up the page cache slot at @mapping & @offset. If there is a * Looks up the page cache entry at @mapping & @offset. If there is a
* page cache page, it is returned locked and with an increased * page cache page, it is returned locked and with an increased
* refcount. * refcount.
* *
* Otherwise, %NULL is returned. * Context: May sleep.
* * Return: A struct page or %NULL if there is no page in the cache for this
* find_lock_page() may sleep. * index.
*/ */
static inline struct page *find_lock_page(struct address_space *mapping, static inline struct page *find_lock_page(struct address_space *mapping,
pgoff_t offset) pgoff_t index)
{
return pagecache_get_page(mapping, index, FGP_LOCK, 0);
}
/**
* find_lock_head - Locate, pin and lock a pagecache page.
* @mapping: The address_space to search.
* @offset: The page index.
*
* Looks up the page cache entry at @mapping & @offset. If there is a
* page cache page, its head page is returned locked and with an increased
* refcount.
*
* Context: May sleep.
* Return: A struct page which is !PageTail, or %NULL if there is no page
* in the cache for this index.
*/
static inline struct page *find_lock_head(struct address_space *mapping,
pgoff_t index)
{ {
return pagecache_get_page(mapping, offset, FGP_LOCK, 0); return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
} }
/** /**
......
...@@ -1737,6 +1737,8 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t index) ...@@ -1737,6 +1737,8 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
* *
* * %FGP_ACCESSED - The page will be marked accessed. * * %FGP_ACCESSED - The page will be marked accessed.
* * %FGP_LOCK - The page is returned locked. * * %FGP_LOCK - The page is returned locked.
* * %FGP_HEAD - If the page is present and a THP, return the head page
* rather than the exact page specified by the index.
* * %FGP_CREAT - If no page is present then a new page is allocated using * * %FGP_CREAT - If no page is present then a new page is allocated using
* @gfp_mask and added to the page cache and the VM's LRU list. * @gfp_mask and added to the page cache and the VM's LRU list.
* The page is returned locked and with an increased refcount. * The page is returned locked and with an increased refcount.
...@@ -1765,7 +1767,6 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, ...@@ -1765,7 +1767,6 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
page = NULL; page = NULL;
if (!page) if (!page)
goto no_page; goto no_page;
page = find_subpage(page, index);
if (fgp_flags & FGP_LOCK) { if (fgp_flags & FGP_LOCK) {
if (fgp_flags & FGP_NOWAIT) { if (fgp_flags & FGP_NOWAIT) {
...@@ -1778,12 +1779,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, ...@@ -1778,12 +1779,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
} }
/* Has the page been truncated? */ /* Has the page been truncated? */
if (unlikely(compound_head(page)->mapping != mapping)) { if (unlikely(page->mapping != mapping)) {
unlock_page(page); unlock_page(page);
put_page(page); put_page(page);
goto repeat; goto repeat;
} }
VM_BUG_ON_PAGE(page->index != index, page); VM_BUG_ON_PAGE(!thp_contains(page, index), page);
} }
if (fgp_flags & FGP_ACCESSED) if (fgp_flags & FGP_ACCESSED)
...@@ -1793,6 +1794,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, ...@@ -1793,6 +1794,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
if (page_is_idle(page)) if (page_is_idle(page))
clear_page_idle(page); clear_page_idle(page);
} }
if (!(fgp_flags & FGP_HEAD))
page = find_subpage(page, index);
no_page: no_page:
if (!page && (fgp_flags & FGP_CREAT)) { if (!page && (fgp_flags & FGP_CREAT)) {
......
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