linux-kernel - [PATCH v2 06/24] ext4: introduce s_min_folio

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Message-Id: <20251107144249.435029-7-libaokun@huaweicloud.com>
Date: Fri,  7 Nov 2025 22:42:31 +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 06/24] ext4: introduce s_min_folio_order for future BS > PS support

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

This commit introduces the s_min_folio_order field to the ext4_sb_info
structure. This field will store the minimum folio order required by the
current filesystem, laying groundwork for future support of block sizes
greater than PAGE_SIZE.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
Reviewed-by: Zhang Yi <yi.zhang@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/ext4.h  |  3 +++
 fs/ext4/inode.c |  3 ++-
 fs/ext4/super.c | 10 +++++-----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3d18e6bf43cf..6fe8cc3bf9a5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1688,6 +1688,9 @@ struct ext4_sb_info {
 	/* record the last minlen when FITRIM is called. */
 	unsigned long s_last_trim_minblks;
 
+	/* minimum folio order of a page cache allocation */
+	unsigned int s_min_folio_order;
+
 	/* Precomputed FS UUID checksum for seeding other checksums */
 	__u32 s_csum_seed;
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 6fec3aa2268a..9faa0cf77075 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5181,7 +5181,8 @@ void ext4_set_inode_mapping_order(struct inode *inode)
 	if (!ext4_should_enable_large_folio(inode))
 		return;
 
-	mapping_set_folio_order_range(inode->i_mapping, 0,
+	mapping_set_folio_order_range(inode->i_mapping,
+				      EXT4_SB(inode->i_sb)->s_min_folio_order,
 				      EXT4_MAX_PAGECACHE_ORDER(inode));
 }
 
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a9fa824487f9..a6314a3de51d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5107,11 +5107,8 @@ static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
 	 * If the default block size is not the same as the real block size,
 	 * we need to reload it.
 	 */
-	if (sb->s_blocksize == blocksize) {
-		*lsb = logical_sb_block;
-		sbi->s_sbh = bh;
-		return 0;
-	}
+	if (sb->s_blocksize == blocksize)
+		goto success;
 
 	/*
 	 * bh must be released before kill_bdev(), otherwise
@@ -5142,6 +5139,9 @@ static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
 		ext4_msg(sb, KERN_ERR, "Magic mismatch, very weird!");
 		goto out;
 	}
+
+success:
+	sbi->s_min_folio_order = get_order(blocksize);
 	*lsb = logical_sb_block;
 	sbi->s_sbh = bh;
 	return 0;
-- 
2.46.1