[PATCH] Btrfs: make sure roots are assigned before freeing their nodes

[Josef Bacik]

If we fail to load the chunk tree we'll call free_root_pointers, except we may
not have assigned the roots for the dev_root/extent_root/csum_root yet, so we
could NULL pointer deref at this point.  Just add checks to make sure these
roots are set to keep us from panicing.  Thanks,

Signed-off-by: Josef Bacik <jba...@fusionio.com>
---
 fs/btrfs/disk-io.c |   39 +++++++++++++++++++++------------------
 1 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1341247..84c4426 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1967,30 +1967,33 @@ static void free_root_pointers(struct btrfs_fs_info 
*info, int chunk_root)
 {
        free_extent_buffer(info->tree_root->node);
        free_extent_buffer(info->tree_root->commit_root);
-       free_extent_buffer(info->dev_root->node);
-       free_extent_buffer(info->dev_root->commit_root);
-       free_extent_buffer(info->extent_root->node);
-       free_extent_buffer(info->extent_root->commit_root);
-       free_extent_buffer(info->csum_root->node);
-       free_extent_buffer(info->csum_root->commit_root);
-       if (info->quota_root) {
-               free_extent_buffer(info->quota_root->node);
-               free_extent_buffer(info->quota_root->commit_root);
-       }
-
        info->tree_root->node = NULL;
        info->tree_root->commit_root = NULL;
-       info->dev_root->node = NULL;
-       info->dev_root->commit_root = NULL;
-       info->extent_root->node = NULL;
-       info->extent_root->commit_root = NULL;
-       info->csum_root->node = NULL;
-       info->csum_root->commit_root = NULL;
+
+       if (info->dev_root) {
+               free_extent_buffer(info->dev_root->node);
+               free_extent_buffer(info->dev_root->commit_root);
+               info->dev_root->node = NULL;
+               info->dev_root->commit_root = NULL;
+       }
+       if (info->extent_root) {
+               free_extent_buffer(info->extent_root->node);
+               free_extent_buffer(info->extent_root->commit_root);
+               info->extent_root->node = NULL;
+               info->extent_root->commit_root = NULL;
+       }
+       if (info->csum_root) {
+               free_extent_buffer(info->csum_root->node);
+               free_extent_buffer(info->csum_root->commit_root);
+               info->csum_root->node = NULL;
+               info->csum_root->commit_root = NULL;
+       }
        if (info->quota_root) {
+               free_extent_buffer(info->quota_root->node);
+               free_extent_buffer(info->quota_root->commit_root);
                info->quota_root->node = NULL;
                info->quota_root->commit_root = NULL;
        }
-
        if (chunk_root) {
                free_extent_buffer(info->chunk_root->node);
                free_extent_buffer(info->chunk_root->commit_root);
-- 
1.7.7.6

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