On Fri, Jun 22, 2018 at 12:32 PM Hans van Kranenburg
<hans.van.kranenb...@mendix.com> wrote:
>
> On 06/22/2018 06:25 PM, Nikolay Borisov wrote:
> >
> >
> > On 22.06.2018 19:17, Su Yue wrote:
> >>
> >>
> >>
> >>> Sent: Friday, June 22, 2018 at 11:26 PM
> >>> From: "Hans van Kranenburg" <hans.van.kranenb...@mendix.com>
> >>> To: "Nikolay Borisov" <nbori...@suse.com>, "Su Yue"
> >>> <suy.f...@cn.fujitsu.com>, linux-btrfs@vger.kernel.org
> >>> Subject: Re: [PATCH] btrfs: Add more details while checking tree block
> >>>
> >>> On 06/22/2018 01:48 PM, Nikolay Borisov wrote:
> >>>>
> >>>>
> >>>> On 22.06.2018 04:52, Su Yue wrote:
> >>>>> For easier debug, print eb->start if level is invalid.
> >>>>> Also make print clear if bytenr found is not expected.
> >>>>>
> >>>>> Signed-off-by: Su Yue <suy.f...@cn.fujitsu.com>
> >>>>> ---
> >>>>> fs/btrfs/disk-io.c | 8 ++++----
> >>>>> 1 file changed, 4 insertions(+), 4 deletions(-)
> >>>>>
> >>>>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> >>>>> index c3504b4d281b..a90dab84f41b 100644
> >>>>> --- a/fs/btrfs/disk-io.c
> >>>>> +++ b/fs/btrfs/disk-io.c
> >>>>> @@ -615,8 +615,8 @@ static int btree_readpage_end_io_hook(struct
> >>>>> btrfs_io_bio *io_bio,
> >>>>>
> >>>>> found_start = btrfs_header_bytenr(eb);
> >>>>> if (found_start != eb->start) {
> >>>>> - btrfs_err_rl(fs_info, "bad tree block start %llu %llu",
> >>>>> - found_start, eb->start);
> >>>>> + btrfs_err_rl(fs_info, "bad tree block start want %llu have
> >>>>> %llu",
> >>>>
> >>>> nit: I'd rather have the want/have in brackets (want %llu have% llu)
> >>>
> >>> From a user support point of view, this text should really be improved.
> >>> There are a few places where 'want' and 'have' are reported in error
> >>> strings, and it's totally unclear what they mean.
> >>>
> >> Yes. The strings are too concise for users to understand errors.
> >> Developers always prefer to avoid "unnecessary" words in logs.
> >>
> >>> Intuitively I'd say when checking a csum, the "want" would be what's on
> >>> disk now, since you want that to be correct, and the "have" would be
> >>> what you have calculated, but it's actually the other way round, or
> >>> wasn't it? Or was it?
> >> For csum, you are right at all.
> >>
> >> In this situation, IIRC bytenr of "have" is read from disk.
> >> Bytenr of "want" is assigned while constructing eb, from parent ptr
> >> , root item and other things which are also read from disk.
> >>>
> >>> Every time someone pastes such a message when we help on IRC for
> >>> example, there's confusion, and I have to look up the source again,
> >>> because I always forget.
> >>
> >> Me too.
> >>>
> >>> What about (%llu stored on disk, %llu calculated now) or something
> >>> similar?
> >
> > Wha tabout expected got
>
> No, that's just as horrible as want and found.
>
> Did you 'expect' the same checksum to be on disk disk as what you 'get'
> when calculating one? Or did you 'expect' the same thing after
> calculation as what you 'got' when reading from disk?
>
> /o\
>
So it's "read | archived | recorded" versus "calculated | generated |
computed" ?
If we want to be succinct, it's "then" versus "now", but that's not as
descriptive.
~ Noah
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