On 2018年03月02日 19:00, Filipe Manana wrote: > On Fri, Mar 2, 2018 at 10:54 AM, Qu Wenruo <quwenruo.bt...@gmx.com> wrote: >> >> >> On 2018年03月02日 18:46, Filipe Manana wrote: >>> On Fri, Mar 2, 2018 at 5:22 AM, Qu Wenruo <w...@suse.com> wrote: >>>> Normally when specifying max_inline, we should normally limit it by >>>> uncompressed extent size, as it's the only thing user can control. >>> >>> Why does it matter that users can control it? Will they write less (or >>> more) data to files because stuff won't get inlined? >>> Why do they care about stuff getting inlined or not? That's an >>> implementation detail of btrfs to speed up access to file data and >>> save some space. >> >> Then why we still have max_inline mount option? > > My comment was about deciding based on which size to make the decision > (compressed vs uncompressed).
The same thing, we have given user options to trigger the behavior, then
we should give them *predictable* option to modify the behavior.
Not something confusing like current max_inline.
Either we give user max_inline and max_inline_compressed, or both follow
max_inline.
Thanks,
Qu
>
>> Just do everything we *think* is best is good enough in that case.
>>
>> If we provide that mount option to allow *user* to specify the behavior,
>> then allow then to do the same control.
>>
>> Thanks,
>> Qu
>>
>>>
>>>> (Control the algorithm and compressed data is almost impossible)
>>>>
>>>> Since btrfs is providing *TRANSPARENT* compression, max_inline should
>>>> behave the same for both plain and compress data.
>>>
>>> Taking away the benefits of compression for. So now some cases that
>>> ended up getting the benefits of inlining won't get them anymore.
>>>
>>> I don't agree with this change.
>>
>>
>>>
>>>>
>>>> So this patch will use @inline_len instead of @data_len in
>>>> cow_file_range_inline() so user will know their max_inline mount option
>>>> works exactly the same for both plain and compressed data extent.
>>>>
>>>> Signed-off-by: Qu Wenruo <w...@suse.com>
>>>> ---
>>>> fs/btrfs/inode.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
>>>> index e1a7f3cb5be9..48472509239b 100644
>>>> --- a/fs/btrfs/inode.c
>>>> +++ b/fs/btrfs/inode.c
>>>> @@ -303,7 +303,7 @@ static noinline int cow_file_range_inline(struct
>>>> btrfs_root *root,
>>>> (!compressed_size &&
>>>> (actual_end & (fs_info->sectorsize - 1)) == 0) ||
>>>> end + 1 < isize ||
>>>> - data_len > fs_info->max_inline) {
>>>> + inline_len > fs_info->max_inline) {
>>>> return 1;
>>>> }
>>>>
>>>> --
>>>> 2.16.2
>>>>
>>>> --
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>>>
>>>
>>>
>>
>
>
>
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