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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,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        Nikolay Borisov <nborisov@suse.com>, Qu Wenruo <wqu@suse.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 5.5 018/150] btrfs: handle logged extent failure properly
Date:   Thu, 27 Feb 2020 14:35:55 +0100
Message-Id: <20200227132235.357370622@linuxfoundation.org>
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From: Josef Bacik <josef@toxicpanda.com>

commit bd727173e4432fe6cb70ba108dc1f3602c5409d7 upstream.

If we're allocating a logged extent we attempt to insert an extent
record for the file extent directly.  We increase
space_info->bytes_reserved, because the extent entry addition will call
btrfs_update_block_group(), which will convert the ->bytes_reserved to
->bytes_used.  However if we fail at any point while inserting the
extent entry we will bail and leave space on ->bytes_reserved, which
will trigger a WARN_ON() on umount.  Fix this by pinning the space if we
fail to insert, which is what happens in every other failure case that
involves adding the extent entry.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/extent-tree.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4430,6 +4430,8 @@ int btrfs_alloc_logged_file_extent(struc
 
 	ret = alloc_reserved_file_extent(trans, 0, root_objectid, 0, owner,
 					 offset, ins, 1);
+	if (ret)
+		btrfs_pin_extent(fs_info, ins->objectid, ins->offset, 1);
 	btrfs_put_block_group(block_group);
 	return ret;
 }