btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr()

At btrfs_del_ptr(), instead of doing a BUG_ON() in case we fail to record
tree mod log operations, do a transaction abort and return the error to
the callers. There's really no need for the BUG_ON() as we can release all
resources in the context of all callers, and we have to abort because other
future tree searches that use the tree mod log (btrfs_search_old_slot())
may get inconsistent results if other operations modify the tree after
that failure and before the tree mod log based search.

This implies btrfs_del_ptr() return an int instead of void, and making all
callers check for returned errors.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index e075e69..190dd90 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1139,7 +1139,12 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                if (btrfs_header_nritems(right) == 0) {
                        btrfs_clear_buffer_dirty(trans, right);
                        btrfs_tree_unlock(right);
-                       btrfs_del_ptr(root, path, level + 1, pslot + 1);
+                       ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
+                       if (ret < 0) {
+                               free_extent_buffer_stale(right);
+                               right = NULL;
+                               goto out;
+                       }
                        root_sub_used(root, right->len);
                        btrfs_free_tree_block(trans, btrfs_root_id(root), right,
                                              0, 1);
@@ -1192,7 +1197,12 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
        if (btrfs_header_nritems(mid) == 0) {
                btrfs_clear_buffer_dirty(trans, mid);
                btrfs_tree_unlock(mid);
-               btrfs_del_ptr(root, path, level + 1, pslot);
+               ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
+               if (ret < 0) {
+                       free_extent_buffer_stale(mid);
+                       mid = NULL;
+                       goto out;
+               }
                root_sub_used(root, mid->len);
                btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
                free_extent_buffer_stale(mid);
@@ -4440,8 +4450,8 @@ int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
  *
  * This is exported for use inside btrfs-progs, don't un-export it.
  */
-void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
-                  int slot)
+int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+                 struct btrfs_path *path, int level, int slot)
 {
        struct extent_buffer *parent = path->nodes[level];
        u32 nritems;
@@ -4452,7 +4462,10 @@ void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
                if (level) {
                        ret = btrfs_tree_mod_log_insert_move(parent, slot,
                                        slot + 1, nritems - slot - 1);
-                       BUG_ON(ret < 0);
+                       if (ret < 0) {
+                               btrfs_abort_transaction(trans, ret);
+                               return ret;
+                       }
                }
                memmove_extent_buffer(parent,
                              btrfs_node_key_ptr_offset(parent, slot),
@@ -4462,7 +4475,10 @@ void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
        } else if (level) {
                ret = btrfs_tree_mod_log_insert_key(parent, slot,
                                                    BTRFS_MOD_LOG_KEY_REMOVE);
-               BUG_ON(ret < 0);
+               if (ret < 0) {
+                       btrfs_abort_transaction(trans, ret);
+                       return ret;
+               }
        }
 
        nritems--;
@@ -4478,6 +4494,7 @@ void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
                fixup_low_keys(path, &disk_key, level + 1);
        }
        btrfs_mark_buffer_dirty(parent);
+       return 0;
 }
 
 /*
@@ -4490,13 +4507,17 @@ void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
  * The path must have already been setup for deleting the leaf, including
  * all the proper balancing.  path->nodes[1] must be locked.
  */
-static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
-                                   struct btrfs_root *root,
-                                   struct btrfs_path *path,
-                                   struct extent_buffer *leaf)
+static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
+                                  struct btrfs_root *root,
+                                  struct btrfs_path *path,
+                                  struct extent_buffer *leaf)
 {
+       int ret;
+
        WARN_ON(btrfs_header_generation(leaf) != trans->transid);
-       btrfs_del_ptr(root, path, 1, path->slots[1]);
+       ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
+       if (ret < 0)
+               return ret;
 
        /*
         * btrfs_free_extent is expensive, we want to make sure we
@@ -4509,6 +4530,7 @@ static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
        atomic_inc(&leaf->refs);
        btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
        free_extent_buffer_stale(leaf);
+       return 0;
 }
 /*
  * delete the item at the leaf level in path.  If that empties
@@ -4558,7 +4580,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                        btrfs_set_header_level(leaf, 0);
                } else {
                        btrfs_clear_buffer_dirty(trans, leaf);
-                       btrfs_del_leaf(trans, root, path, leaf);
+                       ret = btrfs_del_leaf(trans, root, path, leaf);
+                       if (ret < 0)
+                               return ret;
                }
        } else {
                int used = leaf_space_used(leaf, 0, nritems);
@@ -4619,7 +4643,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
                        if (btrfs_header_nritems(leaf) == 0) {
                                path->slots[1] = slot;
-                               btrfs_del_leaf(trans, root, path, leaf);
+                               ret = btrfs_del_leaf(trans, root, path, leaf);
+                               if (ret < 0)
+                                       return ret;
                                free_extent_buffer(leaf);
                                ret = 0;
                        } else {

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5af6148..f2d2b31 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -541,8 +541,8 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
                      struct extent_buffer **cow_ret, u64 new_root_objectid);
 int btrfs_block_can_be_shared(struct btrfs_root *root,
                              struct extent_buffer *buf);
-void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
-                  int slot);
+int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+                 struct btrfs_path *path, int level, int slot);
 void btrfs_extend_item(struct btrfs_path *path, u32 data_size);
 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end);
 int btrfs_split_item(struct btrfs_trans_handle *trans,