Messages in this thread | | | Subject | Re: Too large badblocks sysfs file (was: [PATCH v3 0/7] badblocks improvement for multiple bad block ranges) | From | Coly Li <> | Date | Thu, 23 Sep 2021 15:13:52 +0800 |
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On 9/23/21 2:47 PM, Greg Kroah-Hartman wrote: > 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.
At least I know mdadm uses this sysfs interface for md raid component disks monitoring. It has been in mdadm for around 5 years.
Yes you are right, let it be for existing sysfs interface to avoid breaking things.
>>> 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.
Now I am sure you are very probably not willing to accept the patches, even I know how to do that :-)
> > But ideally, just drop ths api and make a new one please.
OK, then I leave the existing things as what they are, avoid to make them worse.
Thanks for your response.
Coly Li
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