[PATCH] nilfs2: fix missing cleanup on rollforward recovery error

[Ryusuke Konishi <konishi.ryusuke@gmail.com>]

In an error injection test of a routine for mount-time recovery, KASAN
found a use-after-free bug.

It turned out that if data recovery was performed using partial logs
created by dsync writes, but an error occurred before starting the log
writer to create a recovered checkpoint, the inodes whose data had
been recovered were left in the ns_dirty_files list of the nilfs
object and were not freed.

Fix this issue by cleaning up inodes that have read the recovery data
if the recovery routine fails midway before the log writer starts.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Fixes: 0f3e1c7f23f8 ("nilfs2: recovery functions")
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: stable@vger.kernel.org
---
Andrew, please apply this as a bug fix.

This fixes missing cleanup on error that KASAN detected during an
error injection test of recovery on mount.

Thanks,
Ryusuke Konishi

 fs/nilfs2/recovery.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
index b638dc06df2f..61e25a980f73 100644
--- a/fs/nilfs2/recovery.c
+++ b/fs/nilfs2/recovery.c
@@ -715,6 +715,33 @@ static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
 	brelse(bh);
 }
 
+/**
+ * nilfs_abort_roll_forward - cleaning up after a failed rollforward recovery
+ * @nilfs: nilfs object
+ */
+static void nilfs_abort_roll_forward(struct the_nilfs *nilfs)
+{
+	struct nilfs_inode_info *ii, *n;
+	LIST_HEAD(head);
+
+	/* Abandon inodes that have read recovery data */
+	spin_lock(&nilfs->ns_inode_lock);
+	list_splice_init(&nilfs->ns_dirty_files, &head);
+	spin_unlock(&nilfs->ns_inode_lock);
+	if (list_empty(&head))
+		return;
+
+	set_nilfs_purging(nilfs);
+	list_for_each_entry_safe(ii, n, &head, i_dirty) {
+		spin_lock(&nilfs->ns_inode_lock);
+		list_del_init(&ii->i_dirty);
+		spin_unlock(&nilfs->ns_inode_lock);
+
+		iput(&ii->vfs_inode);
+	}
+	clear_nilfs_purging(nilfs);
+}
+
 /**
  * nilfs_salvage_orphan_logs - salvage logs written after the latest checkpoint
  * @nilfs: nilfs object
@@ -773,15 +800,19 @@ int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs,
 		if (unlikely(err)) {
 			nilfs_err(sb, "error %d writing segment for recovery",
 				  err);
-			goto failed;
+			goto put_root;
 		}
 
 		nilfs_finish_roll_forward(nilfs, ri);
 	}
 
- failed:
+put_root:
 	nilfs_put_root(root);
 	return err;
+
+failed:
+	nilfs_abort_roll_forward(nilfs);
+	goto put_root;
 }
 
 /**
-- 
2.34.1