Re: [PATCH 1/2] block: introduce new field flags in block_device

[Yu Kuai]

Hi,

在 2023/11/20 18:45, Hannes Reinecke 写道:
> On 11/20/23 10:38, Yu Kuai wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > There are multiple switches in struct block_device, use seperate bool
> > fields for them is not gracefully. Add a new field flags and replace
> > swithes to a bit, there are no functional changes, and preapre to add
> > a new switch in the next patch.
> >
> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> > ---
> >   block/bdev.c              | 15 ++++++++-------
> >   block/blk-core.c          |  7 ++++---
> >   block/genhd.c             |  8 +++++---
> >   block/ioctl.c             |  2 +-
> >   include/linux/blk_types.h | 12 ++++++------
> >   include/linux/blkdev.h    |  5 +++--
> >   6 files changed, 27 insertions(+), 22 deletions(-)
> >
> > diff --git a/block/bdev.c b/block/bdev.c
> > index fc8d28d77495..cb849bcf61ae 100644
> > --- a/block/bdev.c
> > +++ b/block/bdev.c
> > @@ -408,10 +408,10 @@ struct block_device *bdev_alloc(struct gendisk 
> > *disk, u8 partno)
> >       bdev->bd_partno = partno;
> >       bdev->bd_inode = inode;
> >       bdev->bd_queue = disk->queue;
> > -    if (partno)
> > -        bdev->bd_has_submit_bio = disk->part0->bd_has_submit_bio;
> > +    if (partno && test_bit(BD_FLAG_HAS_SUBMIT_BIO, &disk->part0->flags))
> > +        set_bit(BD_FLAG_HAS_SUBMIT_BIO, &bdev->flags);
> >       else
> > -        bdev->bd_has_submit_bio = false;
> > +        clear_bit(BD_FLAG_HAS_SUBMIT_BIO, &bdev->flags);
> >       bdev->bd_stats = alloc_percpu(struct disk_stats);
> >       if (!bdev->bd_stats) {
> >           iput(inode);
>
> Couldn't you achieve the very same result by using 
> 'READ_ONCE()/WRITE_ONCE()' and keep the structure as-is?

Yes, remove this patch and add a new bool field in the next patch can
work as well, the idea here is replace multiple fields with a single
flag, and just use the flag in next patch. If people thinks add a new
bool field is better, I'll follow that.

Thanks,
Kuai

> Cheers,
>
> Hannes--
> Dr. Hannes Reinecke                   Kernel Storage Architect
> hare@xxxxxxx                              +49 911 74053 688
> SUSE Software Solutions Germany GmbH, Frankenstr. 146, 90461 Nürnberg
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> (HRB 36809, AG Nürnberg)
>
> .