From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm/filemap.c: rewrite pagecache_get_page documentation - These were never called PCG flags; they've been called FGP flags since their introduction in 2014. - The FGP_FOR_MMAP flag was misleadingly documented as if it was an alternative to FGP_CREAT instead of an option to it. - Rename the 'offset' parameter to 'index'. - Capitalisation, formatting, rewording. Link: http://lkml.kernel.org/r/20200318140253.6141-9-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 55 +++++++++++++++++++++++-------------------------- 1 file changed, 26 insertions(+), 29 deletions(-) --- a/mm/filemap.c~mm-rewrite-pagecache_get_page-documentation +++ a/mm/filemap.c @@ -1574,42 +1574,39 @@ repeat: EXPORT_SYMBOL(find_lock_entry); /** - * pagecache_get_page - find and get a page reference - * @mapping: the address_space to search - * @offset: the page index - * @fgp_flags: PCG flags - * @gfp_mask: gfp mask to use for the page cache data page allocation - * - * Looks up the page cache slot at @mapping & @offset. - * - * PCG flags modify how the page is returned. - * - * @fgp_flags can be: - * - * - FGP_ACCESSED: the page will be marked accessed - * - FGP_LOCK: Page is return locked - * - FGP_CREAT: If page is not 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. - * - FGP_FOR_MMAP: Similar to FGP_CREAT, only we want to allow the caller to do - * its own locking dance if the page is already in cache, or unlock the page - * before returning if we had to add the page to pagecache. + * pagecache_get_page - Find and get a reference to a page. + * @mapping: The address_space to search. + * @index: The page index. + * @fgp_flags: %FGP flags modify how the page is returned. + * @gfp_mask: Memory allocation flags to use if %FGP_CREAT is specified. + * + * Looks up the page cache entry at @mapping & @index. + * + * @fgp_flags can be zero or more of these flags: + * + * * %FGP_ACCESSED - The page will be marked accessed. + * * %FGP_LOCK - The page is returned locked. + * * %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. + * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the + * page is already in cache. If the page was allocated, unlock it before + * returning so the caller can do the same dance. * - * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even - * if the GFP flags specified for FGP_CREAT are atomic. + * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even + * if the %GFP flags specified for %FGP_CREAT are atomic. * * If there is a page cache page, it is returned with an increased refcount. * - * Return: the found page or %NULL otherwise. + * Return: The found page or %NULL otherwise. */ -struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, - int fgp_flags, gfp_t gfp_mask) +struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, + int fgp_flags, gfp_t gfp_mask) { struct page *page; repeat: - page = find_get_entry(mapping, offset); + page = find_get_entry(mapping, index); if (xa_is_value(page)) page = NULL; if (!page) @@ -1631,7 +1628,7 @@ repeat: put_page(page); goto repeat; } - VM_BUG_ON_PAGE(page->index != offset, page); + VM_BUG_ON_PAGE(page->index != index, page); } if (fgp_flags & FGP_ACCESSED) @@ -1656,7 +1653,7 @@ no_page: if (fgp_flags & FGP_ACCESSED) __SetPageReferenced(page); - err = add_to_page_cache_lru(page, mapping, offset, gfp_mask); + err = add_to_page_cache_lru(page, mapping, index, gfp_mask); if (unlikely(err)) { put_page(page); page = NULL; _
