f2fs: fix to correct return value of f2fs_trim_fs

We should account trimmed block number from __wait_all_discard_cmd
in __issue_discard_cmd_range, otherwise trimmed blocks returned
by f2fs_trim_fs will be wrong, this patch fixes it.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -1320,21 +1320,22 @@ static unsigned int __wait_discard_cmd_range(struct f2fs_sb_info *sbi,
 	return trimmed;
 }
 
-static void __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
+static unsigned int __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
 						struct discard_policy *dpolicy)
 {
 	struct discard_policy dp;
+	unsigned int discard_blks;
 
-	if (dpolicy) {
-		__wait_discard_cmd_range(sbi, dpolicy, 0, UINT_MAX);
-		return;
-	}
+	if (dpolicy)
+		return __wait_discard_cmd_range(sbi, dpolicy, 0, UINT_MAX);
 
 	/* wait all */
 	__init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, 1);
-	__wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
+	discard_blks = __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
 	__init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, 1);
-	__wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
+	discard_blks += __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
+
+	return discard_blks;
 }
 
 /* This should be covered by global mutex, &sit_i->sentry_lock */
@@ -2368,7 +2369,7 @@ bool f2fs_exist_trim_candidates(struct f2fs_sb_info *sbi,
 	return has_candidate;
 }
 
-static void __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
+static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
 					struct discard_policy *dpolicy,
 					unsigned int start, unsigned int end)
 {
@@ -2378,6 +2379,7 @@ static void __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
 	struct discard_cmd *dc;
 	struct blk_plug plug;
 	int issued;
+	unsigned int trimmed = 0;
 
 next:
 	issued = 0;
@@ -2415,7 +2417,7 @@ static void __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
 
 			blk_finish_plug(&plug);
 			mutex_unlock(&dcc->cmd_lock);
-			__wait_all_discard_cmd(sbi, NULL);
+			trimmed += __wait_all_discard_cmd(sbi, NULL);
 			congestion_wait(BLK_RW_ASYNC, HZ/50);
 			goto next;
 		}
@@ -2429,6 +2431,8 @@ static void __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
 
 	blk_finish_plug(&plug);
 	mutex_unlock(&dcc->cmd_lock);
+
+	return trimmed;
 }
 
 int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
@@ -2486,9 +2490,10 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
 	end_block = START_BLOCK(sbi, end_segno + 1);
 
 	__init_discard_policy(sbi, &dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
-	__issue_discard_cmd_range(sbi, &dpolicy, start_block, end_block);
+	trimmed = __issue_discard_cmd_range(sbi, &dpolicy,
+					start_block, end_block);
 
-	trimmed = __wait_discard_cmd_range(sbi, &dpolicy,
+	trimmed += __wait_discard_cmd_range(sbi, &dpolicy,
 					start_block, end_block);
 	range->len = F2FS_BLK_TO_BYTES(trimmed);
 out: