f2fs: add node_io_flag for bio flags likewise data_io_flag

This patch adds another way to attach bio flags to node writes.

Description:   Give a way to attach REQ_META|FUA to node writes
               given temperature-based bits. Now the bits indicate:
               *      REQ_META     |      REQ_FUA      |
               *    5 |    4 |   3 |    2 |    1 |   0 |
               * Cold | Warm | Hot | Cold | Warm | Hot |
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -333,6 +333,15 @@ Description:	Give a way to attach REQ_META|FUA to data writes
 		*    5 |    4 |   3 |    2 |    1 |   0 |
 		* Cold | Warm | Hot | Cold | Warm | Hot |
 
+What:		/sys/fs/f2fs/<disk>/node_io_flag
+Date:		June 2020
+Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:	Give a way to attach REQ_META|FUA to node writes
+		given temperature-based bits. Now the bits indicate:
+		*      REQ_META     |      REQ_FUA      |
+		*    5 |    4 |   3 |    2 |    1 |   0 |
+		* Cold | Warm | Hot | Cold | Warm | Hot |
+
 What:		/sys/fs/f2fs/<disk>/iostat_period_ms
 Date:		April 2020
 Contact:	"Daeho Jeong" <daehojeong@google.com>

fs/f2fs/data.c

@@ -514,22 +514,28 @@ void f2fs_submit_bio(struct f2fs_sb_info *sbi,
 	__submit_bio(sbi, bio, type);
 }
 
-static void __attach_data_io_flag(struct f2fs_io_info *fio)
+static void __attach_io_flag(struct f2fs_io_info *fio)
 {
 	struct f2fs_sb_info *sbi = fio->sbi;
 	unsigned int temp_mask = (1 << NR_TEMP_TYPE) - 1;
-	unsigned int fua_flag = sbi->data_io_flag & temp_mask;
-	unsigned int meta_flag = (sbi->data_io_flag >> NR_TEMP_TYPE) &
-								temp_mask;
+	unsigned int io_flag, fua_flag, meta_flag;
+
+	if (fio->type == DATA)
+		io_flag = sbi->data_io_flag;
+	else if (fio->type == NODE)
+		io_flag = sbi->node_io_flag;
+	else
+		return;
+
+	fua_flag = io_flag & temp_mask;
+	meta_flag = (io_flag >> NR_TEMP_TYPE) & temp_mask;
+
 	/*
-	 * data io flag bits per temp:
+	 * data/node io flag bits per temp:
 	 *      REQ_META     |      REQ_FUA      |
 	 *    5 |    4 |   3 |    2 |    1 |   0 |
 	 * Cold | Warm | Hot | Cold | Warm | Hot |
 	 */
-	if (fio->type != DATA)
-		return;
-
 	if ((1 << fio->temp) & meta_flag)
 		fio->op_flags |= REQ_META;
 	if ((1 << fio->temp) & fua_flag)
@@ -543,7 +549,7 @@ static void __submit_merged_bio(struct f2fs_bio_info *io)
 	if (!io->bio)
 		return;
 
-	__attach_data_io_flag(fio);
+	__attach_io_flag(fio);
 	bio_set_op_attrs(io->bio, fio->op, fio->op_flags);
 
 	if (is_read_io(fio->op))

fs/f2fs/f2fs.h

@@ -1568,6 +1568,7 @@ struct f2fs_sb_info {
 
 	/* to attach REQ_META|REQ_FUA flags */
 	unsigned int data_io_flag;
+	unsigned int node_io_flag;
 
 	/* For sysfs suppport */
 	struct kobject s_kobj;

fs/f2fs/sysfs.c

@@ -554,6 +554,7 @@ F2FS_RW_ATTR(FAULT_INFO_RATE, f2fs_fault_info, inject_rate, inject_rate);
 F2FS_RW_ATTR(FAULT_INFO_TYPE, f2fs_fault_info, inject_type, inject_type);
 #endif
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, data_io_flag, data_io_flag);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, node_io_flag, node_io_flag);
 F2FS_GENERAL_RO_ATTR(dirty_segments);
 F2FS_GENERAL_RO_ATTR(free_segments);
 F2FS_GENERAL_RO_ATTR(lifetime_write_kbytes);
@@ -635,6 +636,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(inject_type),
 #endif
 	ATTR_LIST(data_io_flag),
+	ATTR_LIST(node_io_flag),
 	ATTR_LIST(dirty_segments),
 	ATTR_LIST(free_segments),
 	ATTR_LIST(unusable),