From: Matthew Wilcox <mawilcox@linuxonhyperv.com>
To: linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Konstantin Khlebnikov <koct9i@gmail.com>,
        Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: linux-fsdevel@vger.kernel.org, Matthew Wilcox <mawilcox@microsoft.com>,
        linux-mm@kvack.org,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH 18/29] btrfs: Fix race in btrfs_free_dummy_fs_info()
Date: Wed, 16 Nov 2016 16:17:21 -0800
Message-Id: <1479341856-30320-57-git-send-email-mawilcox@linuxonhyperv.com>
In-Reply-To: <1479341856-30320-1-git-send-email-mawilcox@linuxonhyperv.com>
References: <1479341856-30320-1-git-send-email-mawilcox@linuxonhyperv.com>
Sender: linux-kernel-owner@vger.kernel.org
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Lines: 25

From: Matthew Wilcox <mawilcox@microsoft.com>

We drop the lock which protects the radix tree, so we must call
radix_tree_iter_next() in order to avoid a modification to the tree
invalidating the iterator state.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 fs/btrfs/tests/btrfs-tests.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index bf62ad9..73076a0 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -162,6 +162,7 @@ void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
 				slot = radix_tree_iter_retry(&iter);
 			continue;
 		}
+		slot = radix_tree_iter_next(&iter);
 		spin_unlock(&fs_info->buffer_lock);
 		free_extent_buffer_stale(eb);
 		spin_lock(&fs_info->buffer_lock);
-- 
2.10.2