The patch titled
Subject: nilfs2: do not write dirty data after degenerating to read-only
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
nilfs2-do-not-write-dirty-data-after-degenerating-to-read-only.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-do-not-write-dirty-data-after-degenerating-to-read-only.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Subject: nilfs2: do not write dirty data after degenerating to read-only
Date: Thu, 27 Apr 2023 10:15:26 +0900
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@xxxxxxxxx
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Reported-by: syzbot+2af3bc9585be7f23f290@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://syzkaller.appspot.com/bug?extid=2af3bc9585be7f23f290
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/segment.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/fs/nilfs2/segment.c~nilfs2-do-not-write-dirty-data-after-degenerating-to-read-only
+++ a/fs/nilfs2/segment.c
@@ -2041,6 +2041,9 @@ static int nilfs_segctor_do_construct(st
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(stru
flush_work(&sci->sc_iput_work);
- } while (ret && retrycount-- > 0);
+ } while (ret && ret != -EROFS && retrycount-- > 0);
}
/**
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxx are
nilfs2-fix-infinite-loop-in-nilfs_mdt_get_block.patch
nilfs2-do-not-write-dirty-data-after-degenerating-to-read-only.patch
