Re: [f2fs-dev] [PATCH v2] f2fs: add bug_on when f2fs_gc even fails to get one victim

[Yunlong Song <yunlong.song@huawei.com>]

I think there may be bugs somewhere, since no victim is selected but it 
really needs gc.
What is the size of the data image?

On 2017/10/16 11:25, Chao Yu wrote:
> On 2017/10/14 20:34, Yunlong Song wrote:
>> Do you mean check out-of-space test? I have tried that but no bugon.
> Yes, test recent f2fs codes with kernel 4.13.0-rc1+ in VM, FYI:
>
> kernel BUG at gc.c:1034!
> invalid opcode: 0000 [#1] SMP
> Hardware name: Xen HVM domU, BIOS 4.1.2_115-900.260_ 11/06/2015
> RIP: 0010:f2fs_gc+0x6e5/0x6f0 [f2fs]
> RSP: 0018:ffffc90004af7b40 EFLAGS: 00010202
> RAX: ffff8801b0a15940 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff8801b0a15940 RSI: ffff8801978d5f00 RDI: ffff880128148048
> RBP: ffffc90004af7c38 R08: ffff8801978d5f00 R09: 0000000000000003
> R10: 0000000000000003 R11: ffff8800060703a0 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000001 R15: ffff8801b4279800
> FS:  00007f23493cb740(0000) GS:ffff880216f00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffd05402ff8 CR3: 00000001bffb3000 CR4: 00000000001406e0
> Call Trace:
>   f2fs_balance_fs+0x123/0x140 [f2fs]
>   f2fs_create+0x130/0x240 [f2fs]
>   path_openat+0xee7/0x1360
>   do_filp_open+0x7e/0xd0
>   do_sys_open+0x115/0x1f0
>   SyS_open+0x1e/0x20
>   do_syscall_64+0x6e/0x160
>   entry_SYSCALL64_slow_path+0x25/0x25
>
> Thanks,
>
>> On 2017/10/14 8:17, Chao Yu wrote:
>>> On 2017/10/13 21:31, Yunlong Song wrote:
>>>> This can help us to debug on some corner case.
>>> I can hit this bugon with generic/015 of fstest easily, could have a look at
>>> this?
>>>
>>> Thanks,
>>>
>>>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>>    fs/f2fs/gc.c | 6 +++++-
>>>>    1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>> index 197ebf4..2b03202 100644
>>>> --- a/fs/f2fs/gc.c
>>>> +++ b/fs/f2fs/gc.c
>>>> @@ -986,6 +986,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>>>>    		.ilist = LIST_HEAD_INIT(gc_list.ilist),
>>>>    		.iroot = RADIX_TREE_INIT(GFP_NOFS),
>>>>    	};
>>>> +	bool need_fggc = false;
>>>>    
>>>>    	trace_f2fs_gc_begin(sbi->sb, sync, background,
>>>>    				get_pages(sbi, F2FS_DIRTY_NODES),
>>>> @@ -1018,8 +1019,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>>>>    			if (ret)
>>>>    				goto stop;
>>>>    		}
>>>> -		if (has_not_enough_free_secs(sbi, 0, 0))
>>>> +		if (has_not_enough_free_secs(sbi, 0, 0)) {
>>>>    			gc_type = FG_GC;
>>>> +			need_fggc = true;
>>>> +		}
>>>>    	}
>>>>    
>>>>    	/* f2fs_balance_fs doesn't need to do BG_GC in critical path. */
>>>> @@ -1028,6 +1031,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>>>>    		goto stop;
>>>>    	}
>>>>    	if (!__get_victim(sbi, &segno, gc_type)) {
>>>> +		f2fs_bug_on(sbi, !total_freed && need_fggc);
>>>>    		ret = -ENODATA;
>>>>    		goto stop;
>>>>    	}
>>>>
>>> .
>>>
>
> .
>

-- 
Thanks,
Yunlong Song