linux-kernel - [PATCH] f2fs: add a way to change the desired readahead folio order

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Message-ID: <20251121014846.1971924-1-jaegeuk@kernel.org>
Date: Fri, 21 Nov 2025 01:48:46 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Cc: Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH] f2fs: add a way to change the desired readahead folio order

This patch adds a sysfs entry to change the folio order for readahead.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 fs/f2fs/data.c  | 1 +
 fs/f2fs/f2fs.h  | 3 +++
 fs/f2fs/super.c | 1 +
 fs/f2fs/sysfs.c | 9 +++++++++
 4 files changed, 14 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c80d7960b652..faf1faa27c41 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2764,6 +2764,7 @@ int f2fs_readahead_pages(struct file *file, loff_t offset, loff_t len)
 	while (nrpages) {
 		unsigned long this_chunk = min(nrpages, ra_pages);
 
+		ractl.ra->desired_order = F2FS_I_SB(inode)->ra_folio_order;
 		ractl.ra->ra_pages = this_chunk;
 
 		page_cache_sync_ra(&ractl, this_chunk << 1);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 934287cc5624..0e61e253d861 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1921,6 +1921,9 @@ struct f2fs_sb_info {
 	/* carve out reserved_blocks from total blocks */
 	bool carve_out;
 
+	/* enable large folio. */
+	unsigned int ra_folio_order;
+
 #ifdef CONFIG_F2FS_FS_COMPRESSION
 	struct kmem_cache *page_array_slab;	/* page array entry */
 	unsigned int page_array_slab_size;	/* default page array slab size */
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d47ec718f3be..dabac6f288f0 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4287,6 +4287,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
 			NAT_ENTRY_PER_BLOCK));
 	sbi->allocate_section_hint = le32_to_cpu(raw_super->section_count);
 	sbi->allocate_section_policy = ALLOCATE_FORWARD_NOHINT;
+	sbi->ra_folio_order = 0;
 	F2FS_ROOT_INO(sbi) = le32_to_cpu(raw_super->root_ino);
 	F2FS_NODE_INO(sbi) = le32_to_cpu(raw_super->node_ino);
 	F2FS_META_INO(sbi) = le32_to_cpu(raw_super->meta_ino);
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index c42f4f979d13..2537a25986a6 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -906,6 +906,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "ra_folio_order")) {
+		if (t < 0 || t > MAX_PAGECACHE_ORDER)
+			return -EINVAL;
+		sbi->ra_folio_order = t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -1180,6 +1187,7 @@ F2FS_SBI_GENERAL_RW_ATTR(migration_window_granularity);
 F2FS_SBI_GENERAL_RW_ATTR(dir_level);
 F2FS_SBI_GENERAL_RW_ATTR(allocate_section_hint);
 F2FS_SBI_GENERAL_RW_ATTR(allocate_section_policy);
+F2FS_SBI_GENERAL_RW_ATTR(ra_folio_order);
 #ifdef CONFIG_F2FS_IOSTAT
 F2FS_SBI_GENERAL_RW_ATTR(iostat_enable);
 F2FS_SBI_GENERAL_RW_ATTR(iostat_period_ms);
@@ -1422,6 +1430,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(reserved_pin_section),
 	ATTR_LIST(allocate_section_hint),
 	ATTR_LIST(allocate_section_policy),
+	ATTR_LIST(ra_folio_order),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs);
-- 
2.52.0.487.g5c8c507ade-goog