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.
Signed-off-by: Ryusuke Konishi <[email protected]>
Reported-by: [email protected]
Link: https://syzkaller.appspot.com/bug?extid=2af3bc9585be7f23f290
Tested-by: Ryusuke Konishi <[email protected]>
Cc: <[email protected]>
---
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);
}
/**
--
2.34.1