linux-kernel - [PATCH] f2fs: do not use granularity control for segment or section unit discard

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Message-ID: <20250220154904.2698964-1-daeho43@gmail.com>
Date: Thu, 20 Feb 2025 07:49:04 -0800
From: Daeho Jeong <daeho43@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	kernel-team@...roid.com
Cc: Daeho Jeong <daehojeong@...gle.com>,
	Yohan Joung <yohan.joung@...com>
Subject: [PATCH] f2fs: do not use granularity control for segment or section unit discard

From: Daeho Jeong <daehojeong@...gle.com>

When we support segment or section unit discard, we should only focus on
how actively we submit discard commands for only one type of size, such
as segment or section. In this case, we don't have to manage smaller
sized discards.

Reported-by: Yohan Joung <yohan.joung@...com>
Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
---
 fs/f2fs/segment.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index c282e8a0a2ec..4316ff7aa0d1 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1661,12 +1661,20 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
 				f2fs_time_over(sbi, UMOUNT_DISCARD_TIMEOUT))
 			break;
 
-		if (i + 1 < dpolicy->granularity)
-			break;
+		/*
+		 * Do not granularity control for segment or section
+		 * unit discard, since we have only one type of discard length.
+		 */
+		if (f2fs_block_unit_discard(sbi)) {
+			if (i + 1 < dpolicy->granularity)
+				break;
 
-		if (i + 1 < dcc->max_ordered_discard && dpolicy->ordered) {
-			__issue_discard_cmd_orderly(sbi, dpolicy, &issued);
-			return issued;
+			if (i + 1 < dcc->max_ordered_discard &&
+					dpolicy->ordered) {
+				__issue_discard_cmd_orderly(sbi, dpolicy,
+						&issued);
+				return issued;
+			}
 		}
 
 		pend_list = &dcc->pend_list[i];
@@ -1701,6 +1709,13 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
 
 		if (issued >= dpolicy->max_requests || io_interrupted)
 			break;
+
+		/*
+		 * We only use the largest discard unit for segment or
+		 * section unit discard.
+		 */
+		if (!f2fs_block_unit_discard(sbi))
+			break;
 	}
 
 	if (dpolicy->type == DPOLICY_UMOUNT && issued) {
@@ -2320,10 +2335,6 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
 	dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
 	dcc->max_ordered_discard = DEFAULT_MAX_ORDERED_DISCARD_GRANULARITY;
 	dcc->discard_io_aware = DPOLICY_IO_AWARE_ENABLE;
-	if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SEGMENT)
-		dcc->discard_granularity = BLKS_PER_SEG(sbi);
-	else if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SECTION)
-		dcc->discard_granularity = BLKS_PER_SEC(sbi);
 
 	INIT_LIST_HEAD(&dcc->entry_list);
 	for (i = 0; i < MAX_PLIST_NUM; i++)
-- 
2.48.1.601.g30ceb7b040-goog