linux-kernel - [PATCH 25/25] ext4: enable block size larger than page size

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Message-Id: <20251025032221.2905818-26-libaokun@huaweicloud.com>
Date: Sat, 25 Oct 2025 11:22:21 +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,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	chengzhihao1@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH 25/25] ext4: enable block size larger than page size

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

Since block device (See commit 3c20917120ce ("block/bdev: enable large
folio support for large logical block sizes")) and page cache (See commit
ab95d23bab220ef8 ("filemap: allocate mapping_min_order folios in the page
cache")) has the ability to have a minimum order when allocating folio,
and ext4 has supported large folio in commit 7ac67301e82f ("ext4: enable
large folio for regular file"), now add support for block_size > PAGE_SIZE
in ext4.

set_blocksize() -> bdev_validate_blocksize() already validates the block
size, so ext4_load_super() does not need to perform additional checks.

Here we only need to enable large folio by default when s_min_folio_order
is greater than 0 and add the FS_LBS bit to fs_flags.

In addition, mark this feature as experimental.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
Reviewed-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/inode.c | 3 +++
 fs/ext4/super.c | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 04f9380d4211..ba6cf05860ae 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5146,6 +5146,9 @@ static bool ext4_should_enable_large_folio(struct inode *inode)
 	if (!ext4_test_mount_flag(sb, EXT4_MF_LARGE_FOLIO))
 		return false;
 
+	if (EXT4_SB(sb)->s_min_folio_order)
+		return true;
+
 	if (!S_ISREG(inode->i_mode))
 		return false;
 	if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index fdc006a973aa..4c0bd79bdf68 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5053,6 +5053,9 @@ static int ext4_check_large_folio(struct super_block *sb)
 		return -EINVAL;
 	}
 
+	if (sb->s_blocksize > PAGE_SIZE)
+		ext4_msg(sb, KERN_NOTICE, "EXPERIMENTAL bs(%lu) > ps(%lu) enabled.",
+			 sb->s_blocksize, PAGE_SIZE);
 	return 0;
 }
 
@@ -7432,7 +7435,8 @@ static struct file_system_type ext4_fs_type = {
 	.init_fs_context	= ext4_init_fs_context,
 	.parameters		= ext4_param_specs,
 	.kill_sb		= ext4_kill_sb,
-	.fs_flags		= FS_REQUIRES_DEV | FS_ALLOW_IDMAP | FS_MGTIME,
+	.fs_flags		= FS_REQUIRES_DEV | FS_ALLOW_IDMAP | FS_MGTIME |
+				  FS_LBS,
 };
 MODULE_ALIAS_FS("ext4");
 
-- 
2.46.1