On Fri, Jul 29, 2016 at 11:09:50AM -0700, Liu Bo wrote: > Function start_transaction() can return ERR_PTR(1) when flush is > BTRFS_RESERVE_FLUSH_LIMIT, so the call graph is > > start_transaction (return ERR_PTR(1)) > -> btrfs_block_rsv_add (return 1) > -> reserve_metadata_bytes (return 1) > -> flush_space (return 1) > -> do_chunk_alloc (return 1) > > With BTRFS_RESERVE_FLUSH_LIMIT, if flush_space is already on the > flush_state of ALLOC_CHUNK and it successfully allocates a new > chunk, then instead of trying to reserve space again, > reserve_metadata_bytes returns 1 immediately. > > Eventually the callers who call start_transaction() usually just > do the IS_ERR() check which ERR_PTR(1) can pass, then it'll get > a panic when dereferencing a pointer which is ERR_PTR(1). > > The following patch fixes the above problem. > "btrfs: flush_space: treat return value of do_chunk_alloc properly" > https://patchwork.kernel.org/patch/7778651/ > > This add comments to clarify do_chunk_alloc()'s return value. > > Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx> Patch queued, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
