linux-kernel - [PATCH v2 21/24] ext4: make data=journal support large block size

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Message-Id: <20251107144249.435029-22-libaokun@huaweicloud.com>
Date: Fri,  7 Nov 2025 22:42:46 +0800
From: libaokun@...weicloud.com
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	kernel@...kajraghav.com,
	mcgrof@...nel.org,
	ebiggers@...nel.org,
	willy@...radead.org,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	chengzhihao1@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH v2 21/24] ext4: make data=journal support large block size

From: Baokun Li <libaokun1@...wei.com>

Currently, ext4_set_inode_mapping_order() does not set max folio order
for files with the data journalling flag. For files that already have
large folios enabled, ext4_inode_journal_mode() ignores the data
journalling flag once max folio order is set.

This is not because data journalling cannot work with large folios, but
because credit estimates will go through the roof if there are too many
blocks per folio.

Since the real constraint is blocks-per-folio, to support data=journal
under LBS, we now set max folio order to be equal to min folio order for
files with the journalling flag. When LBS is disabled, the max folio order
remains unset as before.

Additionally, the max_order check in ext4_inode_journal_mode() is removed,
and mapping order is reset in ext4_change_inode_journal_flag().

Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 fs/ext4/ext4_jbd2.c |  3 +--
 fs/ext4/inode.c     | 14 ++++++++++----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index a0e66bc10093..05e5946ed9b3 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -16,8 +16,7 @@ int ext4_inode_journal_mode(struct inode *inode)
 	    ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE) ||
 	    test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
 	    (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
-	    !test_opt(inode->i_sb, DELALLOC) &&
-	    !mapping_large_folio_support(inode->i_mapping))) {
+	    !test_opt(inode->i_sb, DELALLOC))) {
 		/* We do not support data journalling for encrypted data */
 		if (S_ISREG(inode->i_mode) && IS_ENCRYPTED(inode))
 			return EXT4_INODE_ORDERED_DATA_MODE;  /* ordered */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 22d215f90c64..517701024d18 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5152,9 +5152,6 @@ static bool ext4_should_enable_large_folio(struct inode *inode)
 
 	if (!S_ISREG(inode->i_mode))
 		return false;
-	if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
-	    ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
-		return false;
 	if (ext4_has_feature_verity(sb))
 		return false;
 	if (ext4_has_feature_encrypt(sb))
@@ -5172,12 +5169,20 @@ static bool ext4_should_enable_large_folio(struct inode *inode)
 		umin(MAX_PAGECACHE_ORDER, (11 + (i)->i_blkbits - PAGE_SHIFT))
 void ext4_set_inode_mapping_order(struct inode *inode)
 {
+	u32 max_order;
+
 	if (!ext4_should_enable_large_folio(inode))
 		return;
 
+	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
+	    ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
+		max_order = EXT4_SB(inode->i_sb)->s_min_folio_order;
+	else
+		max_order = EXT4_MAX_PAGECACHE_ORDER(inode);
+
 	mapping_set_folio_order_range(inode->i_mapping,
 				      EXT4_SB(inode->i_sb)->s_min_folio_order,
-				      EXT4_MAX_PAGECACHE_ORDER(inode));
+				      max_order);
 }
 
 struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
@@ -6585,6 +6590,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 		ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
 	}
 	ext4_set_aops(inode);
+	ext4_set_inode_mapping_order(inode);
 
 	jbd2_journal_unlock_updates(journal);
 	ext4_writepages_up_write(inode->i_sb, alloc_ctx);
-- 
2.46.1