On 03/13/2014 01:19 AM, Wang Shilong wrote: > We hit something like the following function call flows: > > |->run_delalloc_range() > |->btrfs_join_transaction() > |->cow_file_range() > |->btrfs_join_transaction() > |->find_free_extent() > |->btrfs_join_transaction() > > Trace infomation can be seen as: > > [ 7411.127040] ------------[ cut here ]------------ > [ 7411.127060] WARNING: CPU: 0 PID: 11557 at fs/btrfs/transaction.c:383 > start_transaction+0x561/0x580 [btrfs]() > [ 7411.127079] CPU: 0 PID: 11557 Comm: kworker/u8:9 Tainted: G O > 3.13.0+ #4 > [ 7411.127080] Hardware name: LENOVO QiTianM4350/ , BIOS F1KT52AUS 05/24/2013 > [ 7411.127085] Workqueue: writeback bdi_writeback_workfn (flush-btrfs-5) > [ 7411.127092] Call Trace: > [ 7411.127097] [<ffffffff815b87b0>] dump_stack+0x45/0x56 > [ 7411.127101] [<ffffffff81051ffd>] warn_slowpath_common+0x7d/0xa0 > [ 7411.127102] [<ffffffff810520da>] warn_slowpath_null+0x1a/0x20 > [ 7411.127109] [<ffffffffa0444fb1>] start_transaction+0x561/0x580 [btrfs] > [ 7411.127115] [<ffffffffa0445027>] btrfs_join_transaction+0x17/0x20 [btrfs] > [ 7411.127120] [<ffffffffa0431c91>] find_free_extent+0xa21/0xb50 [btrfs] > [ 7411.127126] [<ffffffffa0431f68>] btrfs_reserve_extent+0xa8/0x1a0 [btrfs] > [ 7411.127131] [<ffffffffa04322ce>] btrfs_alloc_free_block+0xee/0x440 [btrfs] > [ 7411.127137] [<ffffffffa043bd6e>] ? btree_set_page_dirty+0xe/0x10 [btrfs] > [ 7411.127142] [<ffffffffa041da51>] __btrfs_cow_block+0x121/0x530 [btrfs] > [ 7411.127146] [<ffffffffa041dfff>] btrfs_cow_block+0x11f/0x1c0 [btrfs] > [ 7411.127151] [<ffffffffa0421b74>] btrfs_search_slot+0x1d4/0x9c0 [btrfs] > [ 7411.127157] [<ffffffffa0438567>] btrfs_lookup_file_extent+0x37/0x40 > [btrfs] > [ 7411.127163] [<ffffffffa0456bfc>] __btrfs_drop_extents+0x16c/0xd90 [btrfs] > [ 7411.127169] [<ffffffffa0444ae3>] ? start_transaction+0x93/0x580 [btrfs] > [ 7411.127171] [<ffffffff811663e2>] ? kmem_cache_alloc+0x132/0x140 > [ 7411.127176] [<ffffffffa041cd9a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs] > [ 7411.127182] [<ffffffffa044aa61>] cow_file_range_inline+0x181/0x2e0 [btrfs] > [ 7411.127187] [<ffffffffa044aead>] cow_file_range+0x2ed/0x440 [btrfs] > [ 7411.127194] [<ffffffffa0464d7f>] ? free_extent_buffer+0x4f/0xb0 [btrfs] > [ 7411.127200] [<ffffffffa044b38f>] run_delalloc_nocow+0x38f/0xa60 [btrfs] > [ 7411.127207] [<ffffffffa0461600>] ? test_range_bit+0x30/0x180 [btrfs] > [ 7411.127212] [<ffffffffa044bd48>] run_delalloc_range+0x2e8/0x350 [btrfs] > [ 7411.127219] [<ffffffffa04618f9>] ? find_lock_delalloc_range+0x1a9/0x1e0 > [btrfs] > [ 7411.127222] [<ffffffff812a1e71>] ? blk_queue_bio+0x2c1/0x330 > [ 7411.127228] [<ffffffffa0462ad4>] __extent_writepage+0x2f4/0x760 [btrfs] > > Here we fix it by avoiding joining transaction again if we have held > a transaction handle when allocating chunk in find_free_extent(). > >
So I just put that warning there to see if we were ever embedding 3 joins at a time, not because it was an actual problem, I'd say just kill the warning. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
