Hi!
I recently posted a message that addresses the usage of BUG_ON for memory
shortages concerning btrfs_alloc_path() (see [1]):
...
path = btrfs_alloc_path();
BUG_ON(!path);
ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
...
It seems that this is not the only place where NULL pointers returned by
allocation functions are not handled properly. For instance in
start_transaction(), errors are not handled at all:
struct btrfs_trans_handle *h =
kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
...
/* Access h without check */
...
return h;
Repairing this would sometimes require to review a bunch of functions that
directly or indirectly refer to it. As pointed out by Andi Kleen two weeks ago
in a reply to message by Diego Calleja (see [2] and [3]), this might not be
trivial, because these errors are sometimes not handled at all in highlevel
functions.
However, is there any interest in patches fixing these problems? If yes: what
would be the best strategy? Should we start fixing this "layer by layer" -- the
low-level functions first and the high-level functions later on? Or should use
come kind of "vertical approach" -- one low-level function and all of its
callers at once?
If these issues currently don't have a very high priority, we could collect
them in a TODO section in the Wiki or something. Any suggestions?
Cheers,
Andi
[1] http://www.spinics.net/lists/linux-btrfs/msg03221.html
[2] http://www.spinics.net/lists/linux-btrfs/msg03197.html
[3] http://www.spinics.net/lists/linux-btrfs/msg03198.html
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