linux-kernel - [PATCH] f2fs: Fix indefinite loop in f2fs

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Message-Id: <1564377626-12898-1-git-send-email-stummala@codeaurora.org>
Date:   Mon, 29 Jul 2019 10:50:26 +0530
From:   Sahitya Tummala <stummala@...eaurora.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <yuchao0@...wei.com>,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     Sahitya Tummala <stummala@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] f2fs: Fix indefinite loop in f2fs_gc()

Policy - foreground GC, LFS mode and greedy GC mode.

Under this policy, f2fs_gc() loops forever to GC as it doesn't have
enough free segements to proceed and thus it keeps calling gc_more
for the same victim segment.  This can happen if the selected victim
segment could not be GC'd due to failed blkaddr validity check i.e.
is_alive() returns false for the blocks set in current validity map.

Fix this by not resetting the sbi->cur_victim_sec to NULL_SEGNO, when
the segment selected could not be GC'd. This helps to select another
segment for GC and thus helps to proceed forward with GC.

Signed-off-by: Sahitya Tummala <stummala@...eaurora.org>
---
 fs/f2fs/gc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 8974672..7bbcc4a 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1303,7 +1303,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
 		round++;
 	}

-	if (gc_type == FG_GC)
+	if (gc_type == FG_GC && seg_freed)
 		sbi->cur_victim_sec = NULL_SEGNO;

 	if (sync)
-- 
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Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.