linux-kernel - [PATCH AUTOSEL 5.4 064/330] f2fs: stop GC when the victim becomes fully valid

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Date:   Thu, 17 Sep 2020 21:56:44 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>, Ramon Pantin <pantin@...gle.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: [PATCH AUTOSEL 5.4 064/330] f2fs: stop GC when the victim becomes fully valid

From: Jaegeuk Kim <jaegeuk@...nel.org>

[ Upstream commit 803e74be04b32f7785742dcabfc62116718fbb06 ]

We must stop GC, once the segment becomes fully valid. Otherwise, it can
produce another dirty segments by moving valid blocks in the segment partially.

Ramon hit no free segment panic sometimes and saw this case happens when
validating reliable file pinning feature.

Signed-off-by: Ramon Pantin <pantin@...gle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/f2fs/gc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index e611d768efde3..a78aa5480454f 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1012,8 +1012,14 @@ next_step:
 		block_t start_bidx;
 		nid_t nid = le32_to_cpu(entry->nid);
 
-		/* stop BG_GC if there is not enough free sections. */
-		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
+		/*
+		 * stop BG_GC if there is not enough free sections.
+		 * Or, stop GC if the segment becomes fully valid caused by
+		 * race condition along with SSR block allocation.
+		 */
+		if ((gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) ||
+				get_valid_blocks(sbi, segno, false) ==
+							sbi->blocks_per_seg)
 			return submitted;
 
 		if (check_valid_map(sbi, segno, off) == 0)
-- 
2.25.1