mirror of https://gitee.com/openkylin/linux.git
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>
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@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
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#define FGP_NOFS 0x00000010
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#define FGP_NOWAIT 0x00000020
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#define FGP_FOR_MMAP 0x00000040
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#define FGP_HEAD 0x00000080
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struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
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int fgp_flags, gfp_t cache_gfp_mask);
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@ -310,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
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* @mapping: the address_space to search
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* @offset: the page index
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*
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* Looks up the page cache slot at @mapping & @offset. If there is a
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* Looks up the page cache entry at @mapping & @offset. If there is a
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* page cache page, it is returned locked and with an increased
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* refcount.
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*
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* Otherwise, %NULL is returned.
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*
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* find_lock_page() may sleep.
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* Context: May sleep.
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* Return: A struct page or %NULL if there is no page in the cache for this
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* index.
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*/
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static inline struct page *find_lock_page(struct address_space *mapping,
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pgoff_t offset)
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pgoff_t index)
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{
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return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
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return pagecache_get_page(mapping, index, FGP_LOCK, 0);
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}
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/**
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* find_lock_head - Locate, pin and lock a pagecache page.
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* @mapping: The address_space to search.
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* @offset: The page index.
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*
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* Looks up the page cache entry at @mapping & @offset. If there is a
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* page cache page, its head page is returned locked and with an increased
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* refcount.
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*
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* Context: May sleep.
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* Return: A struct page which is !PageTail, or %NULL if there is no page
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* in the cache for this index.
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*/
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static inline struct page *find_lock_head(struct address_space *mapping,
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pgoff_t index)
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{
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return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
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}
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/**
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@ -1737,6 +1737,8 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
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*
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* * %FGP_ACCESSED - The page will be marked accessed.
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* * %FGP_LOCK - The page is returned locked.
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* * %FGP_HEAD - If the page is present and a THP, return the head page
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* rather than the exact page specified by the index.
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* * %FGP_CREAT - If no page is present then a new page is allocated using
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* @gfp_mask and added to the page cache and the VM's LRU list.
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* The page is returned locked and with an increased refcount.
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@ -1765,7 +1767,6 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
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page = NULL;
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if (!page)
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goto no_page;
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page = find_subpage(page, index);
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if (fgp_flags & FGP_LOCK) {
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if (fgp_flags & FGP_NOWAIT) {
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@ -1778,12 +1779,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
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}
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/* Has the page been truncated? */
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if (unlikely(compound_head(page)->mapping != mapping)) {
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if (unlikely(page->mapping != mapping)) {
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unlock_page(page);
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put_page(page);
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goto repeat;
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}
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VM_BUG_ON_PAGE(page->index != index, page);
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VM_BUG_ON_PAGE(!thp_contains(page, index), page);
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}
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if (fgp_flags & FGP_ACCESSED)
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@ -1793,6 +1794,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
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if (page_is_idle(page))
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clear_page_idle(page);
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}
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if (!(fgp_flags & FGP_HEAD))
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page = find_subpage(page, index);
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no_page:
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if (!page && (fgp_flags & FGP_CREAT)) {
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