linux-kernel - [RFC PATCH 2/3] mm/filemap: Avoid modifying iocb->ki_flags for AIO in filemap_get

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Message-ID: <20250723101825.607184-3-chizhiling@163.com>
Date: Wed, 23 Jul 2025 18:18:24 +0800
From: Chi Zhiling <chizhiling@....com>
To: akpm@...ux-foundation.org,
	willy@...radead.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Chi Zhiling <chizhiling@...inos.cn>
Subject: [RFC PATCH 2/3] mm/filemap: Avoid modifying iocb->ki_flags for AIO in filemap_get_pages()

From: Chi Zhiling <chizhiling@...inos.cn>

Setting IOCB_NOWAIT in filemap_get_pages() for AIO is only used to
indicate not to block in the filemap_update_page(), with no other purpose.
Moreover, in filemap_read(), IOCB_NOWAIT will be set again for AIO.

Therefore, adding a parameter to the filemap_update_page function to
explicitly indicate not to block serves the same purpose as indicating
through iocb->ki_flags, thus avoiding modifications to iocb->ki_flags.

This patch does not change the original logic and is preparation for the
next patch.

Signed-off-by: Chi Zhiling <chizhiling@...inos.cn>
---
 mm/filemap.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index af12d1cecc7d..350080f579ef 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2454,11 +2454,15 @@ static bool filemap_range_uptodate(struct address_space *mapping,
 
 static int filemap_update_page(struct kiocb *iocb,
 		struct address_space *mapping, size_t count,
-		struct folio *folio, bool need_uptodate)
+		struct folio *folio, bool need_uptodate,
+		bool no_wait)
 {
 	int error;
+	int flags = iocb->ki_flags;
+	if (no_wait)
+		flags |= IOCB_NOWAIT;
 
-	if (iocb->ki_flags & IOCB_NOWAIT) {
+	if (flags & IOCB_NOWAIT) {
 		if (!filemap_invalidate_trylock_shared(mapping))
 			return -EAGAIN;
 	} else {
@@ -2467,9 +2471,9 @@ static int filemap_update_page(struct kiocb *iocb,
 
 	if (!folio_trylock(folio)) {
 		error = -EAGAIN;
-		if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO))
+		if (flags & (IOCB_NOWAIT | IOCB_NOIO))
 			goto unlock_mapping;
-		if (!(iocb->ki_flags & IOCB_WAITQ)) {
+		if (!(flags & IOCB_WAITQ)) {
 			filemap_invalidate_unlock_shared(mapping);
 			/*
 			 * This is where we usually end up waiting for a
@@ -2493,7 +2497,7 @@ static int filemap_update_page(struct kiocb *iocb,
 		goto unlock;
 
 	error = -EAGAIN;
-	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
+	if (flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
 		goto unlock;
 
 	error = filemap_read_folio(iocb->ki_filp, mapping->a_ops->read_folio,
@@ -2621,11 +2625,13 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count,
 			goto err;
 	}
 	if (!folio_test_uptodate(folio)) {
+		bool no_wait = false;
+
 		if ((iocb->ki_flags & IOCB_WAITQ) &&
 		    folio_batch_count(fbatch) > 1)
-			iocb->ki_flags |= IOCB_NOWAIT;
+			no_wait = true;
 		err = filemap_update_page(iocb, mapping, count, folio,
-					  need_uptodate);
+					  need_uptodate, no_wait);
 		if (err)
 			goto err;
 	}
-- 
2.43.0