Commit d454a273 authored Apr 07, 2019 by Liu Xiang Committed by Theodore Ts'o Apr 07, 2019

ext4: fix prefetchw of NULL page



In ext4_mpage_readpages(), if the parameter pages is not NULL, another
parameter page is NULL. At the first time prefetchw(&page->flags)
works on NULL. From second time, prefetchw(&page->flags) always works on
the last consumed page. This might do little improvment for handling
current page. So prefetchw() should be called while the page pointer
has just been updated.

Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent 742b06b5

fs/ext4/readpage.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -127,9 +127,10 @@ int ext4_mpage_readpages(struct address_space *mapping,
		int fully_mapped = 1;
		unsigned first_hole = blocks_per_page;

		prefetchw(&page->flags);
		if (pages) {
		page = lru_to_page(pages);

		prefetchw(&page->flags);
		list_del(&page->lru);
		if (add_to_page_cache_lru(page, mapping, page->index,
		readahead_gfp_mask(mapping)))