Re: [PATCH v2] mtd: mtd_blkdevs: Initialize rq.limits.discard_granularity

[Zhihao Cheng]

在 2021/6/18 15:52, Miquel Raynal 写道:
> Hi Zhihao,
>
> Zhihao Cheng <chengzhihao1@xxxxxxxxxx> wrote on Tue, 15 Jun 2021
> 17:39:05 +0800:
>
> > Since commit b35fd7422c2f8("block: check queue's limits.discard_granularity
> > in __blkdev_issue_discard()") checks rq.limits.discard_granularity in
> > __blkdev_issue_discard(), we may get following warnings on formatted ftl:
> >
> >    WARNING: CPU: 2 PID: 7313 at block/blk-lib.c:51
> >    __blkdev_issue_discard+0x2a7/0x390
> >
> > Reproducer:
> >    1. ftl_format /dev/mtd0
> >    2. modprobe ftl
> >    3. mkfs.vfat /dev/ftla
> >    4. mount -odiscard /dev/ftla temp
> >    5. dd if=/dev/zero of=temp/tst bs=1M count=10 oflag=direct
> >    6. dd if=/dev/zero of=temp/tst bs=1M count=10 oflag=direct
> >
> > Fix it by initializing rq.limits.discard_granularity if device supports
> > discard operation.
>
> Can you please verify that this is still needed after Christoph's
> additional fix:
> https://patchwork.kernel.org/project/xen-devel/patch/20210602065345.355274-10-hch@xxxxxx/
Hi, Miquel,
I can still reproduce the problem after [1] applied.
I look through this series patches and I didn't find out 
'rq.limits.discard_granularity' has been initialized somewhere. The 
patchset is aming at reconstructing to avoid boilerplate code in drivers?
So 'rq.limits.discard_granularity' still need to be initialized in 
mtdblock driver.

[1] 
https://patchwork.kernel.org/project/xen-devel/patch/20210602065345.355274-10-hch@xxxxxx/

>