f2fs: introduce sysfs/data_io_flag to attach REQ_META/FUA

This patch introduces a way to attach REQ_META/FUA explicitly
to all the data writes given temperature.

-> attach REQ_FUA to Hot Data writes

-> attach REQ_FUA to Hot|Warm Data writes

-> attach REQ_FUA to Hot|Warm|Cold Data writes

-> attach REQ_FUA to Hot|Warm|Cold Data writes as well as
          REQ_META to Hot Data writes
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -323,3 +323,12 @@ What:		/sys/fs/f2fs/<disk>/mounted_time_sec
 Date:		February 2020
 Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
 Description:	Show the mounted time in secs of this partition.
+
+What:		/sys/fs/f2fs/<disk>/data_io_flag
+Date:		April 2020
+Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:	Give a way to attach REQ_META|FUA to data 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 |

fs/f2fs/data.c

@@ -513,6 +513,28 @@ 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)
+{
+	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;
+	/*
+	 * data 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)
+		fio->op_flags |= REQ_FUA;
+}
+
 static void __submit_merged_bio(struct f2fs_bio_info *io)
 {
 	struct f2fs_io_info *fio = &io->fio;
@@ -520,6 +542,7 @@ static void __submit_merged_bio(struct f2fs_bio_info *io)
 	if (!io->bio)
 		return;
 
+	__attach_data_io_flag(fio);
 	bio_set_op_attrs(io->bio, fio->op, fio->op_flags);
 
 	if (is_read_io(fio->op))

fs/f2fs/f2fs.h

@@ -1507,6 +1507,9 @@ struct f2fs_sb_info {
 	unsigned long long write_iostat[NR_IO_TYPE];
 	bool iostat_enable;
 
+	/* to attach REQ_META|REQ_FUA flags */
+	unsigned int data_io_flag;
+
 	/* For sysfs suppport */
 	struct kobject s_kobj;
 	struct completion s_kobj_unregister;

fs/f2fs/sysfs.c

@@ -372,7 +372,6 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
-
 	if (!strcmp(a->attr.name, "iostat_enable")) {
 		sbi->iostat_enable = !!t;
 		if (!sbi->iostat_enable)
@@ -543,6 +542,7 @@ F2FS_RW_ATTR(F2FS_SBI, f2fs_super_block, extension_list, extension_list);
 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_GENERAL_RO_ATTR(dirty_segments);
 F2FS_GENERAL_RO_ATTR(free_segments);
 F2FS_GENERAL_RO_ATTR(lifetime_write_kbytes);
@@ -622,6 +622,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(inject_rate),
 	ATTR_LIST(inject_type),
 #endif
+	ATTR_LIST(data_io_flag),
 	ATTR_LIST(dirty_segments),
 	ATTR_LIST(free_segments),
 	ATTR_LIST(unusable),