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nilfs2: do not write dirty data after degenerating to read-only

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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>
This commit is contained in:
Ryusuke Konishi 2023-04-27 10:15:26 +09:00 committed by Andrew Morton
parent d824ec2a15
commit 28a65b49eb
1 changed files with 4 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
fs/nilfs2/segment.c
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@ -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; struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
int err; int err;
if (sb_rdonly(sci->sc_super))
return -EROFS;
nilfs_sc_cstage_set(sci, NILFS_ST_INIT); nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
sci->sc_cno = nilfs->ns_cno; 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); flush_work(&sci->sc_iput_work);
} while (ret && retrycount-- > 0); } while (ret && ret != -EROFS && retrycount-- > 0);
} }
/** /**