On Tue, Nov 21, 2023 at 11:28:56PM -0800, Christoph Hellwig wrote:
> > + if (partno && bdev_flagged(disk->part0, BD_FLAG_HAS_SUBMIT_BIO))
> > + bdev_set_flag(bdev, BD_FLAG_HAS_SUBMIT_BIO);
> > else
> > + bdev_clear_flag(bdev, BD_FLAG_HAS_SUBMIT_BIO);
>
> While the block layer has a bit of history of using wrappers for
> testing, setting and clearing flags, I have to say I always find them
> rather confusing when reading the code.
>
> > +#define BD_FLAG_READ_ONLY 0 /* read-only-policy */
>
> I know this is copied from the existing field, but can you expand
> it a bit?
>
> > +#define BD_FLAG_WRITE_HOLDER 1
> > +#define BD_FLAG_HAS_SUBMIT_BIO 2
> > +#define BD_FLAG_MAKE_IT_FAIL 3
>
> And also write comments for these.
>
> > +
> > struct block_device {
> > sector_t bd_start_sect;
> > sector_t bd_nr_sectors;
> > @@ -44,10 +49,8 @@ struct block_device {
> > struct request_queue * bd_queue;
> > struct disk_stats __percpu *bd_stats;
> > unsigned long bd_stamp;
> > - bool bd_read_only; /* read-only policy */
> > + unsigned short bd_flags;
>
> I suspect you really need an unsigned long and atomic bit ops here.
> Even a lock would probably not work on alpha as it could affect
> the other fields in the same 32-bit alignment.
All the existed 'bool' flags are not atomic RW, so I think it isn't
necessary to define 'bd_flags' as 'unsigned long' for replacing them.
Thanks,
Ming
