f2fs: issue discard with finally produced len and minlen

This patch determines to issue discard commands by comparing given minlen and
the length of produced final candidates.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index d31fbf6..61d06b7 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -552,10 +552,6 @@
 			break;
 
 		end = __find_rev_next_zero_bit(dmap, max_blocks, start + 1);
-
-		if (force && end - start < cpc->trim_minlen)
-			continue;
-
 		__add_discard_entry(sbi, cpc, se, start, end);
 	}
 }
@@ -586,7 +582,7 @@
 	mutex_unlock(&dirty_i->seglist_lock);
 }
 
-void clear_prefree_segments(struct f2fs_sb_info *sbi)
+void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 {
 	struct list_head *head = &(SM_I(sbi)->discard_list);
 	struct discard_entry *entry, *this;
@@ -619,7 +615,10 @@
 
 	/* send small discards */
 	list_for_each_entry_safe(entry, this, head, list) {
+		if (cpc->reason == CP_DISCARD && entry->len < cpc->trim_minlen)
+			goto skip;
 		f2fs_issue_discard(sbi, entry->blkaddr, entry->len);
+skip:
 		list_del(&entry->list);
 		SM_I(sbi)->nr_discards -= entry->len;
 		kmem_cache_free(discard_entry_slab, entry);
@@ -1061,8 +1060,7 @@
 	unsigned int start_segno, end_segno;
 	struct cp_control cpc;
 
-	if (range->minlen > SEGMENT_SIZE(sbi) || start >= MAX_BLKADDR(sbi) ||
-						range->len < sbi->blocksize)
+	if (start >= MAX_BLKADDR(sbi) || range->len < sbi->blocksize)
 		return -EINVAL;
 
 	cpc.trimmed = 0;
@@ -1074,7 +1072,7 @@
 	end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
 						GET_SEGNO(sbi, end);
 	cpc.reason = CP_DISCARD;
-	cpc.trim_minlen = F2FS_BYTES_TO_BLK(range->minlen);
+	cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));
 
 	/* do checkpoint to issue discard commands safely */
 	for (; start_segno <= end_segno; start_segno = cpc.trim_end + 1) {