f2fs: move discard parameters into discard_cmd_control

This patch unifies parameters related to how often discard is issued and
how many requests go out at the same time by placing them in
discard_cmd_control. The move will allow the parameters to be modified
in the future without relying on hard-coded values.
Signed-off-by: Konstantin Vyshetsky <vkon@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -398,6 +398,10 @@ struct discard_cmd_control {
 	struct mutex cmd_lock;
 	unsigned int nr_discards;		/* # of discards in the list */
 	unsigned int max_discards;		/* max. discards to be issued */
+	unsigned int max_discard_request;	/* max. discard request per round */
+	unsigned int min_discard_issue_time;	/* min. interval between discard issue */
+	unsigned int mid_discard_issue_time;	/* mid. interval between discard issue */
+	unsigned int max_discard_issue_time;	/* max. interval between discard issue */
 	unsigned int discard_granularity;	/* discard granularity */
 	unsigned int undiscard_blks;		/* # of undiscard blocks */
 	unsigned int next_pos;			/* next discard position */

fs/f2fs/segment.c

@@ -1156,14 +1156,14 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi,
 	dpolicy->ordered = false;
 	dpolicy->granularity = granularity;
 
-	dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
+	dpolicy->max_requests = dcc->max_discard_request;
 	dpolicy->io_aware_gran = MAX_PLIST_NUM;
 	dpolicy->timeout = false;
 
 	if (discard_type == DPOLICY_BG) {
-		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
-		dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
-		dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
+		dpolicy->min_interval = dcc->min_discard_issue_time;
+		dpolicy->mid_interval = dcc->mid_discard_issue_time;
+		dpolicy->max_interval = dcc->max_discard_issue_time;
 		dpolicy->io_aware = true;
 		dpolicy->sync = false;
 		dpolicy->ordered = true;
@@ -1171,12 +1171,12 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi,
 			dpolicy->granularity = 1;
 			if (atomic_read(&dcc->discard_cmd_cnt))
 				dpolicy->max_interval =
-					DEF_MIN_DISCARD_ISSUE_TIME;
+					dcc->min_discard_issue_time;
 		}
 	} else if (discard_type == DPOLICY_FORCE) {
-		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
-		dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
-		dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
+		dpolicy->min_interval = dcc->min_discard_issue_time;
+		dpolicy->mid_interval = dcc->mid_discard_issue_time;
+		dpolicy->max_interval = dcc->max_discard_issue_time;
 		dpolicy->io_aware = false;
 	} else if (discard_type == DPOLICY_FSTRIM) {
 		dpolicy->io_aware = false;
@@ -1781,7 +1781,7 @@ static int issue_discard_thread(void *data)
 	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
 	wait_queue_head_t *q = &dcc->discard_wait_queue;
 	struct discard_policy dpolicy;
-	unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
+	unsigned int wait_ms = dcc->min_discard_issue_time;
 	int issued;
 
 	set_freezable();
@@ -2180,6 +2180,10 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
 	atomic_set(&dcc->discard_cmd_cnt, 0);
 	dcc->nr_discards = 0;
 	dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
+	dcc->max_discard_request = DEF_MAX_DISCARD_REQUEST;
+	dcc->min_discard_issue_time = DEF_MIN_DISCARD_ISSUE_TIME;
+	dcc->mid_discard_issue_time = DEF_MID_DISCARD_ISSUE_TIME;
+	dcc->max_discard_issue_time = DEF_MAX_DISCARD_ISSUE_TIME;
 	dcc->undiscard_blks = 0;
 	dcc->next_pos = 0;
 	dcc->root = RB_ROOT_CACHED;