[037/173] mm/filemap: don't call ->readpage if IOCB_WAITQ is set

Commit Message

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

From: "Matthew Wilcox (Oracle)" <[e-mail]>
Subject: mm/filemap: don't call ->readpage if IOCB_WAITQ is set

The readpage operation can block in many (most?) filesystems, so we should
punt to a work queue instead of calling it.  This was the last caller of
lock_page_for_iocb(), so remove it.

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 |   14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

Patch

--- a/mm/filemap.c~mm-filemap-dont-call-readpage-if-iocb_waitq-is-set
+++ a/mm/filemap.c
@@ -2154,16 +2154,6 @@  static void shrink_readahead_size_eio(st
 	ra->ra_pages /= 4;
 }
 
-static int lock_page_for_iocb(struct kiocb *iocb, struct page *page)
-{
-	if (iocb->ki_flags & IOCB_WAITQ)
-		return lock_page_async(page, iocb->ki_waitq);
-	else if (iocb->ki_flags & IOCB_NOWAIT)
-		return trylock_page(page) ? 0 : -EAGAIN;
-	else
-		return lock_page_killable(page);
-}
-
 /*
  * filemap_get_read_batch - Get a batch of pages for read
  *
@@ -2215,7 +2205,7 @@  static struct page *filemap_read_page(st
 	struct file_ra_state *ra = &filp->f_ra;
 	int error;
 
-	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT)) {
+	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) {
 		unlock_page(page);
 		put_page(page);
 		return ERR_PTR(-EAGAIN);
@@ -2236,7 +2226,7 @@  static struct page *filemap_read_page(st
 	}
 
 	if (!PageUptodate(page)) {
-		error = lock_page_for_iocb(iocb, page);
+		error = lock_page_killable(page);
 		if (unlikely(error)) {
 			put_page(page);
 			return ERR_PTR(error);