f2fs: split discard policy

There are many different scenarios such as fstrim, umount, urgent or
background where we will issue discards, actually, they need use
different policy in aspect of io aware, discard granularity, delay
interval and so on. But now they just share one common discard policy,
so there will be race when changing policy in between these scenarios,
the interference of changing discard policy will be very serious.

This patch changes to split discard policy for different scenarios.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -208,10 +208,6 @@ struct discard_entry {
 #define plist_idx(blk_num)	((blk_num) >= MAX_PLIST_NUM ?		\
 					(MAX_PLIST_NUM - 1) : (blk_num - 1))
 
-#define P_ACTIVE	0x01
-#define P_TRIM		0x02
-#define plist_issue(tag)	(((tag) & P_ACTIVE) || ((tag) & P_TRIM))
-
 enum {
 	D_PREP,
 	D_SUBMIT,
@@ -243,13 +239,23 @@ struct discard_cmd {
 	int error;			/* bio error */
 };
 
+enum {
+	DPOLICY_BG,
+	DPOLICY_FORCE,
+	DPOLICY_FSTRIM,
+	DPOLICY_UMOUNT,
+	MAX_DPOLICY,
+};
+
 struct discard_policy {
+	int type;			/* type of discard */
 	unsigned int min_interval;	/* used for candidates exist */
 	unsigned int max_interval;	/* used for candidates not exist */
 	unsigned int max_requests;	/* # of discards issued per round */
 	unsigned int io_aware_gran;	/* minimum granularity discard not be aware of I/O */
 	bool io_aware;			/* issue discard in idle time */
 	bool sync;			/* submit discard with REQ_SYNC flag */
+	unsigned int granularity;	/* discard granularity */
 };
 
 struct discard_cmd_control {
@@ -270,7 +276,6 @@ struct discard_cmd_control {
 	atomic_t issing_discard;		/* # of issing discard */
 	atomic_t discard_cmd_cnt;		/* # of cached cmd count */
 	struct rb_root root;			/* root of discard rb-tree */
-	struct discard_policy dpolicy;		/* current discard policy */
 };
 
 /* for the list of fsync inodes, used only during recovery */
@@ -2544,6 +2549,8 @@ int f2fs_flush_device_cache(struct f2fs_sb_info *sbi);
 void destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free);
 void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr);
 bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr);
+void init_discard_policy(struct discard_policy *dpolicy, int discard_type,
+						unsigned int granularity);
 void refresh_sit_entry(struct f2fs_sb_info *sbi, block_t old, block_t new);
 void stop_discard_thread(struct f2fs_sb_info *sbi);
 void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi);

fs/f2fs/segment.h

@@ -796,8 +796,9 @@ static inline void wake_up_discard_thread(struct f2fs_sb_info *sbi, bool force)
 		goto wake_up;
 
 	mutex_lock(&dcc->cmd_lock);
-	for (i = MAX_PLIST_NUM - 1;
-			i >= 0 && plist_issue(dcc->pend_list_tag[i]); i--) {
+	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
+		if (i + 1 < dcc->discard_granularity)
+			break;
 		if (!list_empty(&dcc->pend_list[i])) {
 			wakeup = true;
 			break;

fs/f2fs/sysfs.c

@@ -154,23 +154,10 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
 	}
 
 	if (!strcmp(a->attr.name, "discard_granularity")) {
-		struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
-		int i;
-
 		if (t == 0 || t > MAX_PLIST_NUM)
 			return -EINVAL;
 		if (t == *ui)
 			return count;
-
-		mutex_lock(&dcc->cmd_lock);
-		for (i = 0; i < MAX_PLIST_NUM; i++) {
-			if (i >= t - 1)
-				dcc->pend_list_tag[i] |= P_ACTIVE;
-			else
-				dcc->pend_list_tag[i] &= (~P_ACTIVE);
-		}
-		mutex_unlock(&dcc->cmd_lock);
-
 		*ui = t;
 		return count;
 	}