f2fs: add f2fs_gc exception handle in f2fs_ioc_gc_range

When f2fs_ioc_gc_range performs multiple segments gc ops, the return
value of f2fs_ioc_gc_range is determined by the last segment gc ops.
If its ops failed, the f2fs_ioc_gc_range will be considered to be failed
despite some of previous segments gc ops succeeded. Therefore, so we
fix: Redefine the return value of getting victim ops and add exception
handle for f2fs_gc. In particular, 1).if target has no valid block, it
will go on. 2).if target sectoion has valid block(s), but it is current
section, we will reminder the caller.
Signed-off-by: Qilong Zhang <zhangqilong3@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -2525,6 +2525,11 @@ static int f2fs_ioc_gc_range(struct file *filp, unsigned long arg)
 	}
 
 	ret = f2fs_gc(sbi, range.sync, true, GET_SEGNO(sbi, range.start));
+	if (ret) {
+		if (ret == -EBUSY)
+			ret = -EAGAIN;
+		goto out;
+	}
 	range.start += BLKS_PER_SEC(sbi);
 	if (range.start <= end)
 		goto do_more;

fs/f2fs/gc.c

@@ -330,6 +330,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
 	unsigned int secno, last_victim;
 	unsigned int last_segment;
 	unsigned int nsearched = 0;
+	int ret = 0;
 
 	mutex_lock(&dirty_i->seglist_lock);
 	last_segment = MAIN_SECS(sbi) * sbi->segs_per_sec;
@@ -341,12 +342,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
 	p.min_cost = get_max_cost(sbi, &p);
 
 	if (*result != NULL_SEGNO) {
-		if (get_valid_blocks(sbi, *result, false) &&
-			!sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result)))
+		if (!get_valid_blocks(sbi, *result, false)) {
+			ret = -ENODATA;
+			goto out;
+		}
+
+		if (sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result)))
+			ret = -EBUSY;
+		else
 			p.min_segno = *result;
 		goto out;
 	}
 
+	ret = -ENODATA;
 	if (p.max_search == 0)
 		goto out;
 
@@ -447,6 +455,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
 			else
 				set_bit(secno, dirty_i->victim_secmap);
 		}
+		ret = 0;
 
 	}
 out:
@@ -456,7 +465,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
 				prefree_segments(sbi), free_segments(sbi));
 	mutex_unlock(&dirty_i->seglist_lock);
 
-	return (p.min_segno == NULL_SEGNO) ? 0 : 1;
+	return ret;
 }
 
 static const struct victim_selection default_v_ops = {
@@ -1340,10 +1349,9 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
 		ret = -EINVAL;
 		goto stop;
 	}
-	if (!__get_victim(sbi, &segno, gc_type)) {
-		ret = -ENODATA;
+	ret = __get_victim(sbi, &segno, gc_type);
+	if (ret)
 		goto stop;
-	}
 
 	seg_freed = do_garbage_collect(sbi, segno, &gc_list, gc_type);
 	if (gc_type == FG_GC && seg_freed == sbi->segs_per_sec)

fs/f2fs/segment.c

@@ -2631,7 +2631,7 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
 	bool reversed = false;
 
 	/* f2fs_need_SSR() already forces to do this */
-	if (v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
+	if (!v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
 		curseg->next_segno = segno;
 		return 1;
 	}
@@ -2658,7 +2658,7 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
 	for (; cnt-- > 0; reversed ? i-- : i++) {
 		if (i == type)
 			continue;
-		if (v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
+		if (!v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
 			curseg->next_segno = segno;
 			return 1;
 		}