f2fs: assign the write hint per stream by default

This reverts commit 930e260 ("f2fs: remove obsolete whint_mode"), as we
decide to pass write hints to the disk.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/filesystems/f2fs.rst

@@ -774,6 +774,35 @@ In order to identify whether the data in the victim segment are valid or not,
 F2FS manages a bitmap. Each bit represents the validity of a block, and the
 bitmap is composed of a bit stream covering whole blocks in main area.
 
+Write-hint Policy
+-----------------
+
+F2FS sets the whint all the time with the below policy.
+
+===================== ======================== ===================
+User                  F2FS                     Block
+===================== ======================== ===================
+N/A                   META                     WRITE_LIFE_NONE|REQ_META
+N/A                   HOT_NODE                 WRITE_LIFE_NONE
+N/A                   WARM_NODE                WRITE_LIFE_MEDIUM
+N/A                   COLD_NODE                WRITE_LIFE_LONG
+ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
+extension list        "                        "
+
+-- buffered io
+N/A                   COLD_DATA                WRITE_LIFE_EXTREME
+N/A                   HOT_DATA                 WRITE_LIFE_SHORT
+N/A                   WARM_DATA                WRITE_LIFE_NOT_SET
+
+-- direct io
+WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
+WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
+WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
+WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
+WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
+WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
+===================== ======================== ===================
+
 Fallocate(2) Policy
 -------------------
 

fs/f2fs/data.c

@@ -465,6 +465,8 @@ static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
 	} else {
 		bio->bi_end_io = f2fs_write_end_io;
 		bio->bi_private = sbi;
+		bio->bi_write_hint = f2fs_io_type_to_rw_hint(sbi,
+						fio->type, fio->temp);
 	}
 	iostat_alloc_and_bind_ctx(sbi, bio, NULL);
 

fs/f2fs/f2fs.h

@@ -3745,6 +3745,8 @@ void f2fs_destroy_segment_manager(struct f2fs_sb_info *sbi);
 int __init f2fs_create_segment_manager_caches(void);
 void f2fs_destroy_segment_manager_caches(void);
 int f2fs_rw_hint_to_seg_type(enum rw_hint hint);
+enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
+			enum page_type type, enum temp_type temp);
 unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi,
 			unsigned int segno);
 unsigned int f2fs_usable_blks_in_seg(struct f2fs_sb_info *sbi,

fs/f2fs/segment.c

@@ -3364,6 +3364,65 @@ int f2fs_rw_hint_to_seg_type(enum rw_hint hint)
 	}
 }
 
+/*
+ * This returns write hints for each segment type. This hints will be
+ * passed down to block layer as below by default.
+ *
+ * User                  F2FS                     Block
+ * ----                  ----                     -----
+ *                       META                     WRITE_LIFE_NONE|REQ_META
+ *                       HOT_NODE                 WRITE_LIFE_NONE
+ *                       WARM_NODE                WRITE_LIFE_MEDIUM
+ *                       COLD_NODE                WRITE_LIFE_LONG
+ * ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
+ * extension list        "                        "
+ *
+ * -- buffered io
+ *                       COLD_DATA                WRITE_LIFE_EXTREME
+ *                       HOT_DATA                 WRITE_LIFE_SHORT
+ *                       WARM_DATA                WRITE_LIFE_NOT_SET
+ *
+ * -- direct io
+ * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
+ * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
+ * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
+ * WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
+ * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
+ * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
+ */
+enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
+				enum page_type type, enum temp_type temp)
+{
+	switch (type) {
+	case DATA:
+		switch (temp) {
+		case WARM:
+			return WRITE_LIFE_NOT_SET;
+		case HOT:
+			return WRITE_LIFE_SHORT;
+		case COLD:
+			return WRITE_LIFE_EXTREME;
+		default:
+			return WRITE_LIFE_NONE;
+		}
+	case NODE:
+		switch (temp) {
+		case WARM:
+			return WRITE_LIFE_MEDIUM;
+		case HOT:
+			return WRITE_LIFE_NONE;
+		case COLD:
+			return WRITE_LIFE_LONG;
+		default:
+			return WRITE_LIFE_NONE;
+		}
+	case META:
+		return WRITE_LIFE_NONE;
+	default:
+		return WRITE_LIFE_NONE;
+	}
+}
+
 static int __get_segment_type_2(struct f2fs_io_info *fio)
 {
 	if (fio->type == DATA)