Re: [PATCH] Btrfs: hold enough space for global_rsv

[Liu Bo <liubo2009@cn.fujitsu.com>]

On 02/27/2012 09:29 PM, Johannes Hirte wrote:
> Am Tue, 17 Jan 2012 17:51:59 +0800
> schrieb Liu Bo <liubo2009@cn.fujitsu.com>:
> 
>> I've kept hitting enospc warnings of global_rsv while running
>> defragment on files:
>> btrfs: block rsv returned -28
>> WARNING: at fs/btrfs/extent-tree.c:5984
>> btrfs_alloc_free_block+0x333/0x340 [btrfs]() ...
>>
>> I used a fio jobs to create a file with lots of fragments:
>> $ filefrag /mnt/btrfs/foobar
>> /mnt/btrfs/foobar: 66964 extents found
>>
>> and then "btrfs fi defrag /mnt/btrfs/foobar && sync" would pop the
>> warnings.
>>
>> I found that the global_rsv size is just not enough for defragment,
>> and didn't find any space leak in using global_rsv, so double it and
>> go ahead.
>>
>> Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
>> ---
>>  fs/btrfs/extent-tree.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index 8603ee4..77ea23c 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -3979,7 +3979,7 @@ static u64 calc_global_metadata_size(struct
>> btrfs_fs_info *fs_info) num_bytes += div64_u64(data_used + meta_used,
>> 50); 
>>  	if (num_bytes * 3 > meta_used)
>> -		num_bytes = div64_u64(meta_used, 3);
>> +		num_bytes = div64_u64(meta_used, 3) * 2;
>>  
>>  	return ALIGN(num_bytes, fs_info->extent_root->leafsize <<
>> 10); }
> 
> This patch breakes my system. With this applied all services fail on
> boot with "no space left" messages.
> 

It's weird since this patch is just aiming to enlarge our metadata reservation count.

so you've tried a revert or a bisect, right?  Can you show me the environment or any log messages?

thanks,
liubo