Revert "filemap: Correct the conditions for marking a folio as accessed"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6YDHU
CVE: NA

--------------------------------

This reverts commit 939325bb.

Because this commit make a mistake to judge if the page is the same.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

mm/filemap.c

@@ -2530,13 +2530,6 @@ static int generic_file_buffered_read_get_pages(struct kiocb *iocb,
 	goto find_page;
 }
 
-static inline bool pos_same_page(loff_t pos1, loff_t pos2, struct page *page)
-{
-	unsigned int shift = page_shift(page);
-
-	return (pos1 >> shift == pos2 >> shift);
-}
-
 /**
  * generic_file_buffered_read - generic file read routine
  * @iocb:	the iocb to read
@@ -2627,10 +2620,11 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		writably_mapped = mapping_writably_mapped(mapping);
 
 		/*
-		 * When a read accesses a page several times, only
+		 * When a sequential read accesses a page several times, only
 		 * mark it as accessed the first time.
 		 */
-		if (pos_same_page(iocb->ki_pos, ra->prev_pos -1, pages[0]))
+		if (iocb->ki_pos >> PAGE_SHIFT !=
+		    ra->prev_pos >> PAGE_SHIFT)
 			mark_page_accessed(pages[0]);
 		for (i = 1; i < pg_nr; i++)
 			mark_page_accessed(pages[i]);