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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jan Kara <jack@suse.cz>, stable@kernel.org,
        Theodore Tso <tytso@mit.edu>,
        syzbot+3b6f9218b1301ddda3e2@syzkaller.appspotmail.com
Subject: [PATCH 5.16 0889/1039] ext4: make sure to reset inode lockdep class when quota enabling fails
Date:   Mon, 24 Jan 2022 19:44:38 +0100
Message-Id: <20220124184155.174086253@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
References: <20220124184125.121143506@linuxfoundation.org>
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From: Jan Kara <jack@suse.cz>

commit 4013d47a5307fdb5c13370b5392498b00fedd274 upstream.

When we succeed in enabling some quota type but fail to enable another
one with quota feature, we correctly disable all enabled quota types.
However we forget to reset i_data_sem lockdep class. When the inode gets
freed and reused, it will inherit this lockdep class (i_data_sem is
initialized only when a slab is created) and thus eventually lockdep
barfs about possible deadlocks.

Reported-and-tested-by: syzbot+3b6f9218b1301ddda3e2@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20211007155336.12493-3-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/ext4/super.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6361,8 +6361,19 @@ int ext4_enable_quotas(struct super_bloc
 					"Failed to enable quota tracking "
 					"(type=%d, err=%d). Please run "
 					"e2fsck to fix.", type, err);
-				for (type--; type >= 0; type--)
+				for (type--; type >= 0; type--) {
+					struct inode *inode;
+
+					inode = sb_dqopt(sb)->files[type];
+					if (inode)
+						inode = igrab(inode);
 					dquot_quota_off(sb, type);
+					if (inode) {
+						lockdep_set_quota_inode(inode,
+							I_DATA_SEM_NORMAL);
+						iput(inode);
+					}
+				}
 
 				return err;
 			}