linux-kernel - [PATCH 27/27] ext4: introduce a mount option for iomap buffered I/O path

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Message-ID: <20241022111059.2566137-28-yi.zhang@huaweicloud.com>
Date: Tue, 22 Oct 2024 19:10:58 +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,
	ritesh.list@...il.com,
	hch@...radead.org,
	djwong@...nel.org,
	david@...morbit.com,
	zokeefe@...gle.com,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	chengzhihao1@...wei.com,
	yukuai3@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH 27/27] ext4: introduce a mount option for iomap buffered I/O path

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

Introduce the buffered_iomap and the nobuffered_iomap mount options to
enable the iomap buffered I/O path for regular files. This option is
currently disabled by default until we can support more comprehensive
features along this path.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/ext4.h  | 1 +
 fs/ext4/inode.c | 2 ++
 fs/ext4/super.c | 7 +++++++
 3 files changed, 10 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0096191b454c..c2a44530e026 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1257,6 +1257,7 @@ struct ext4_inode_info {
 						    * scanning in mballoc
 						    */
 #define EXT4_MOUNT2_ABORT		0x00000100 /* Abort filesystem */
+#define EXT4_MOUNT2_BUFFERED_IOMAP	0x00000200 /* Use iomap for buffered IO */
 
 #define clear_opt(sb, opt)		EXT4_SB(sb)->s_mount_opt &= \
 						~EXT4_MOUNT_##opt
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 97abc88e6658..b6e041a423f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5153,6 +5153,8 @@ bool ext4_should_use_buffered_iomap(struct inode *inode)
 {
 	struct super_block *sb = inode->i_sb;
 
+	if (!test_opt2(sb, BUFFERED_IOMAP))
+		return false;
 	if (ext4_has_feature_inline_data(sb))
 		return false;
 	if (ext4_has_feature_verity(sb))
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 89955081c4fe..435a866359d9 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1675,6 +1675,7 @@ enum {
 	Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
 	Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
 	Opt_no_prefetch_block_bitmaps, Opt_mb_optimize_scan,
+	Opt_buffered_iomap, Opt_nobuffered_iomap,
 	Opt_errors, Opt_data, Opt_data_err, Opt_jqfmt, Opt_dax_type,
 #ifdef CONFIG_EXT4_DEBUG
 	Opt_fc_debug_max_replay, Opt_fc_debug_force
@@ -1806,6 +1807,8 @@ static const struct fs_parameter_spec ext4_param_specs[] = {
 	fsparam_flag("no_prefetch_block_bitmaps",
 						Opt_no_prefetch_block_bitmaps),
 	fsparam_s32("mb_optimize_scan",		Opt_mb_optimize_scan),
+	fsparam_flag("buffered_iomap",		Opt_buffered_iomap),
+	fsparam_flag("nobuffered_iomap",	Opt_nobuffered_iomap),
 	fsparam_string("check",			Opt_removed),	/* mount option from ext2/3 */
 	fsparam_flag("nocheck",			Opt_removed),	/* mount option from ext2/3 */
 	fsparam_flag("reservation",		Opt_removed),	/* mount option from ext2/3 */
@@ -1900,6 +1903,10 @@ static const struct mount_opts {
 	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
 	{Opt_no_prefetch_block_bitmaps, EXT4_MOUNT_NO_PREFETCH_BLOCK_BITMAPS,
 	 MOPT_SET},
+	{Opt_buffered_iomap, EXT4_MOUNT2_BUFFERED_IOMAP,
+	 MOPT_SET | MOPT_2 | MOPT_EXT4_ONLY},
+	{Opt_nobuffered_iomap, EXT4_MOUNT2_BUFFERED_IOMAP,
+	 MOPT_CLEAR | MOPT_2 | MOPT_EXT4_ONLY},
 #ifdef CONFIG_EXT4_DEBUG
 	{Opt_fc_debug_force, EXT4_MOUNT2_JOURNAL_FAST_COMMIT,
 	 MOPT_SET | MOPT_2 | MOPT_EXT4_ONLY},
-- 
2.46.1