f2fs: convert to use MIN_DISCARD_GRANULARITY macro

Commit 1cd2e6d5 ("f2fs: define MIN_DISCARD_GRANULARITY macro")
introduce it, let's convert to use MIN_DISCARD_GRANULARITY macro.
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -1604,9 +1604,9 @@ static unsigned int __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
 		return __wait_discard_cmd_range(sbi, dpolicy, 0, UINT_MAX);
 
 	/* wait all */
-	__init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, 1);
+	__init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, MIN_DISCARD_GRANULARITY);
 	discard_blks = __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
-	__init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, 1);
+	__init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, MIN_DISCARD_GRANULARITY);
 	discard_blks += __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
 
 	return discard_blks;
@@ -1689,7 +1689,8 @@ static int issue_discard_thread(void *data)
 
 		if (sbi->gc_mode == GC_URGENT_HIGH ||
 			!f2fs_available_free_memory(sbi, DISCARD_CACHE))
-			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
+			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE,
+						MIN_DISCARD_GRANULARITY);
 		else
 			__init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
 						dcc->discard_granularity);