linux-kernel - [PATCH 2/2] f2fs: fix missing small discard in fstrim

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Message-Id: <20250102101310.580277-2-guochunhai@vivo.com>
Date: Thu,  2 Jan 2025 03:13:09 -0700
From: Chunhai Guo <guochunhai@...o.com>
To: chao@...nel.org,
	jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Chunhai Guo <guochunhai@...o.com>
Subject: [PATCH 2/2] f2fs: fix missing small discard in fstrim

If userspace issues an fstrim with a range that does not include all
segments with small discards, these segments will be reused without being
discarded. This patch fixes this issue.
This patch is somewhat similar to commit 650d3c4e56e1 ("f2fs: fix a missing
discard prefree segments").

Fixes: d7bc2484b8d4 ("f2fs: fix small discards not to issue redundantly")
Signed-off-by: Chunhai Guo <guochunhai@...o.com>
---
 fs/f2fs/segment.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8fe9f794b581..af9a62591c49 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4552,6 +4552,8 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	struct list_head *head = &SM_I(sbi)->sit_entry_set;
 	bool to_journal = !is_sbi_flag_set(sbi, SBI_IS_RESIZEFS);
 	struct seg_entry *se;
+	bool force = (cpc->reason & CP_DISCARD);
+	__u64 trim_start = cpc->trim_start;
 
 	down_write(&sit_i->sentry_lock);
 
@@ -4609,7 +4611,9 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 #endif
 
 			/* add discard candidates */
-			if (!(cpc->reason & CP_DISCARD)) {
+			if (!force || (force &&
+					(segno < trim_start ||
+					 segno > cpc->trim_end))) {
 				cpc->trim_start = segno;
 				add_discard_addrs(sbi, cpc, false, false);
 			}
@@ -4649,8 +4653,8 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	f2fs_bug_on(sbi, !list_empty(head));
 	f2fs_bug_on(sbi, sit_i->dirty_sentries);
 out:
-	if (cpc->reason & CP_DISCARD) {
-		__u64 trim_start = cpc->trim_start;
+	if (force) {
+		cpc->trim_start = trim_start;
 
 		for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
 			add_discard_addrs(sbi, cpc, true, false);
-- 
2.34.1