linux-ext4 - [PATCH 5/5] ext4: disable large folios if dioread

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Message-ID: <20250530062858.458039-6-yi.zhang@huaweicloud.com>
Date: Fri, 30 May 2025 14:28:58 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ojaswin@...ux.ibm.com,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	libaokun1@...wei.com,
	yukuai3@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH 5/5] ext4: disable large folios if dioread_nolock is not enabled

From: Zhang Yi <yi.zhang@...wei.com>

The write-back process cannot restart a journal transaction when
submitting a sufficiently large and discontinuous folio if
dioread_nolock is disabled. To address this, disable large folios when
building an inode if dioread_nolock is disabled, and also ensure that
dioread_nolock cannot be disabled on an active inode that has large
folio enabled.

Fixes: 7ac67301e82f ("ext4: enable large folio for regular file")
Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/ext4_jbd2.h | 7 +++++++
 fs/ext4/inode.c     | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index c0ee756cb34c..59292da272ef 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -422,6 +422,13 @@ static inline int ext4_free_data_revoke_credits(struct inode *inode, int blocks)
  */
 static inline int ext4_should_dioread_nolock(struct inode *inode)
 {
+	/*
+	 * Cannot disable dioread_nolock on an active inode that has
+	 * large folio enabled.
+	 */
+	if (mapping_large_folio_support(inode->i_mapping))
+		return 1;
+
 	if (!test_opt(inode->i_sb, DIOREAD_NOLOCK))
 		return 0;
 	if (!S_ISREG(inode->i_mode))
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e7de2fafc941..421c7bbc3ca9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5164,6 +5164,8 @@ bool ext4_should_enable_large_folio(struct inode *inode)
 		return false;
 	if (ext4_has_feature_encrypt(sb))
 		return false;
+	if (!ext4_should_dioread_nolock(inode))
+		return false;
 
 	return true;
 }
-- 
2.46.1