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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: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew 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.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-10-13 16:51:41 -07:00 committed by Linus Torvalds
parent 63ec1973dd
commit a8cf7f272b
2 changed files with 32 additions and 9 deletions
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32
include/linux/pagemap.h
View File

@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_NOFS 0x00000010
#define FGP_NOWAIT 0x00000020
#define FGP_FOR_MMAP 0x00000040
#define FGP_HEAD 0x00000080
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask);
@ -310,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
* @mapping: the address_space to search
* @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
* refcount.
*
* Otherwise, %NULL is returned.
*
* find_lock_page() may sleep.
* Context: May sleep.
* Return: A struct page or %NULL if there is no page in the cache for this
* index.
*/
static inline struct page *find_lock_page(struct address_space *mapping,
pgoff_t offset)
pgoff_t index)
{
return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
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, index, FGP_LOCK | FGP_HEAD, 0);
}
/**

9
mm/filemap.c
View File

@ -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_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
* @gfp_mask and added to the page cache and the VM's LRU list.
* 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,
page = NULL;
if (!page)
goto no_page;
page = find_subpage(page, index);
if (fgp_flags & FGP_LOCK) {
if (fgp_flags & FGP_NOWAIT) {
@ -1778,12 +1779,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
}
/* Has the page been truncated? */
if (unlikely(compound_head(page)->mapping != mapping)) {
if (unlikely(page->mapping != mapping)) {
unlock_page(page);
put_page(page);
goto repeat;
}
VM_BUG_ON_PAGE(page->index != index, page);
VM_BUG_ON_PAGE(!thp_contains(page, index), page);
}
if (fgp_flags & FGP_ACCESSED)
@ -1793,6 +1794,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
if (page_is_idle(page))
clear_page_idle(page);
}
if (!(fgp_flags & FGP_HEAD))
page = find_subpage(page, index);
no_page:
if (!page && (fgp_flags & FGP_CREAT)) {