[045/173] mm/filemap: don't relock the page after calling readpage

Commit Message

Andrew Morton Feb. 24, 2021, 8:02 p.m. UTC

From: "Matthew Wilcox (Oracle)" <[e-mail]>
Subject: mm/filemap: don't relock the page after calling readpage

We don't need to get the page lock again; we just need to wait for the I/O
to finish, so use wait_on_page_locked_killable() like the other callers of
->readpage.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: Kent Overstreet <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Cc: Miaohe Lin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/filemap.c |   21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

Patch

--- a/mm/filemap.c~mm-filemap-dont-relock-the-page-after-calling-readpage
+++ a/mm/filemap.c
@@ -2214,23 +2214,16 @@  static int filemap_read_page(struct file
 	error = mapping->a_ops->readpage(file, page);
 	if (error)
 		return error;
-	if (PageUptodate(page))
-		return 0;
 
-	error = lock_page_killable(page);
+	error = wait_on_page_locked_killable(page);
 	if (error)
 		return error;
-	if (!PageUptodate(page)) {
-		if (page->mapping == NULL) {
-			/* page truncated */
-			error = AOP_TRUNCATED_PAGE;
-		} else {
-			shrink_readahead_size_eio(&file->f_ra);
-			error = -EIO;
-		}
-	}
-	unlock_page(page);
-	return error;
+	if (PageUptodate(page))
+		return 0;
+	if (!page->mapping)	/* page truncated */
+		return AOP_TRUNCATED_PAGE;
+	shrink_readahead_size_eio(&file->f_ra);
+	return -EIO;
 }
 
 static bool filemap_range_uptodate(struct address_space *mapping,