Re: [PATCH] btrfs: space-info: fix the wrong trace name for bytes_may_use

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2020/10/14 下午7:44, David Sterba wrote:
> On Mon, Oct 12, 2020 at 02:56:24PM +0800, Qu Wenruo wrote:
>> The trace_name for bytes_may_use should be "may_use", "space_info".
>>
>> Fixes: f3e75e3805e1 ("btrfs: roll tracepoint into btrfs_space_info_update helper")
> 
> This patch reduced all calls to the definition and kept the same output,
> ie. the 'space_info' so it was correct and the Fixes does not seem to be
> right here. You should explain why the 'may_use' is supposed to be
> there.
> 
The next bytes_pinned still uses "pinned" for its name.

And in the DECLARE_SPACE_INFO_UPDATE(), the @trace_name is only passed
to trcae_btrfs_space_reservation(), to indicate the cause of the trace
event.

Under most case, we pass things like "space_info:enospc" for cases we
will going to return -ENOSPC, and for other cases, we pass what we're
reserving for, like in btrfs_delalloc_reserve_metadata().

For the bytes_may_use case, the DECLARE_SPACE_INFO_UPDATE() is
definitely not called for ENOSPC, thus it should what we're reserving for.
Since the declared function has no real context, thus using the
"may_use" looks completely sane to me.

The fixes looks correct, as it looks like a copy-n-paste error from that
commit.

Or did I miss somthing?

Thanks,
Qu


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