linux-kernel - [PATCH 5.4 112/475] f2fs: fix to avoid potential deadlock

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Date:   Thu, 14 Apr 2022 15:08:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chao Yu <yuchao0@...wei.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 112/475] f2fs: fix to avoid potential deadlock

From: Chao Yu <chao@...nel.org>

[ Upstream commit df77fbd8c5b222c680444801ffd20e8bbc90a56e ]

Using f2fs_trylock_op() in f2fs_write_compressed_pages() to avoid potential
deadlock like we did in f2fs_write_single_data_page().

Signed-off-by: Chao Yu <yuchao0@...wei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/f2fs/data.c | 6 +++++-
 fs/f2fs/node.c | 6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 1679f9c0b63b..773028921c48 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2467,8 +2467,12 @@ static int __f2fs_write_data_pages(struct address_space *mapping,
 	/* to avoid spliting IOs due to mixed WB_SYNC_ALL and WB_SYNC_NONE */
 	if (wbc->sync_mode == WB_SYNC_ALL)
 		atomic_inc(&sbi->wb_sync_req[DATA]);
-	else if (atomic_read(&sbi->wb_sync_req[DATA]))
+	else if (atomic_read(&sbi->wb_sync_req[DATA])) {
+		/* to avoid potential deadlock */
+		if (current->plug)
+			blk_finish_plug(current->plug);
 		goto skip_write;
+	}
 
 	if (__should_serialize_io(inode, wbc)) {
 		mutex_lock(&sbi->writepages);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 0cd1d51dde06..3dc7cc3d6ac6 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1995,8 +1995,12 @@ static int f2fs_write_node_pages(struct address_space *mapping,
 
 	if (wbc->sync_mode == WB_SYNC_ALL)
 		atomic_inc(&sbi->wb_sync_req[NODE]);
-	else if (atomic_read(&sbi->wb_sync_req[NODE]))
+	else if (atomic_read(&sbi->wb_sync_req[NODE])) {
+		/* to avoid potential deadlock */
+		if (current->plug)
+			blk_finish_plug(current->plug);
 		goto skip_write;
+	}
 
 	trace_f2fs_writepages(mapping->host, wbc, NODE);
 
-- 
2.34.1