On Thu, Sep 23, 2021 at 02:14:12PM +0800, Coly Li wrote:
> On 9/23/21 2:08 PM, Greg Kroah-Hartman wrote:
> > On Thu, Sep 23, 2021 at 01:59:28PM +0800, Coly Li wrote:
> > > Hi all the kernel gurus, and folks in mailing lists,
> > >
> > > This is a question about exporting 4KB+ text information via sysfs
> > > interface. I need advice on how to handle the problem.
>
> Hi Greg,
>
> This is the code in mainline kernel for quite long time.
{sigh}
What tools rely on this? If none, just don't add new stuff to the file
and work to create a new api instead.
> > Please do not do that. Seriously, that is not what sysfs is for, and is
> > an abuse of it.
> >
> > sysfs is for "one value per file" and should never even get close to a
> > 4kb limit. If it does, you are doing something really really wrong and
> > should just remove that sysfs file from the system and redesign your
> > api.
>
> I understand this. And what I addressed is the problem I need to fix.
>
> The code is there for almost 10 years, I just find it during my work on bad
> blocks API fixing.
>
>
> > > Recently I work on the bad blocks API (block/badblocks.c) improvement, there
> > > is a sysfs file to export the bad block ranges for me raid. E.g for a md
> > > raid1 device, file
> > > /sys/block/md0/md/rd0/bad_blocks
> > > may contain the following text content,
> > > 64 32
> > > 128 8
> > Ick, again, that's not ok at all. sysfs files should never have to be
> > parsed like this.
>
> I cannot agree more with you. What I am asking for was ---- how to fix it ?
Best solution, come up with a new api.
Worst solution, you are stuck with the existing file and I can show you
the "way out" of dealing with files larger than 4kb in sysfs that a
number of other apis are being forced to do as they grow over time.
But ideally, just drop ths api and make a new one please.
thanks,
greg k-h
