From 28a65b49eb53e172d23567005465019658bfdb4d Mon Sep 17 00:00:00 2001
From: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Date: Thu, 27 Apr 2023 10:15:26 +0900
Subject: [PATCH] nilfs2: do not write dirty data after degenerating to read-only
Git-commit: 28a65b49eb53e172d23567005465019658bfdb4d
Patch-mainline: v6.4-rc1
References: git-fixes
According to syzbot's report, mark_buffer_dirty() called from
nilfs_segctor_do_construct() outputs a warning with some patterns after
nilfs2 detects metadata corruption and degrades to read-only mode.
After such read-only degeneration, page cache data may be cleared through
nilfs_clear_dirty_page() which may also clear the uptodate flag for their
buffer heads. However, even after the degeneration, log writes are still
performed by unmount processing etc., which causes mark_buffer_dirty() to
be called for buffer heads without the "uptodate" flag and causes the
warning.
Since any writes should not be done to a read-only file system in the
first place, this fixes the warning in mark_buffer_dirty() by letting
nilfs_segctor_do_construct() abort early if in read-only mode.
This also changes the retry check of nilfs_segctor_write_out() to avoid
unnecessary log write retries if it detects -EROFS that
nilfs_segctor_do_construct() returned.
Link: https://lkml.kernel.org/r/20230427011526.13457-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+2af3bc9585be7f23f290@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=2af3bc9585be7f23f290
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
fs/nilfs2/segment.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 228659612c0d..ac949fd7603f 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2041,6 +2041,9 @@ static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
int err;
+ if (sb_rdonly(sci->sc_super))
+ return -EROFS;
+
nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
sci->sc_cno = nilfs->ns_cno;
@@ -2724,7 +2727,7 @@ static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
flush_work(&sci->sc_iput_work);
- } while (ret && retrycount-- > 0);
+ } while (ret && ret != -EROFS && retrycount-- > 0);
}
/**
--
2.35.3