Re: [PATCH v3 2/6] badblocks: add helper routines for badblock ranges handling

[Coly Li]

On 9/27/21 3:25 PM, Geliang Tang wrote:
> On 9/14/21 00:36, Coly Li wrote:
> > This patch adds several helper routines to improve badblock ranges
> > handling. These helper routines will be used later in the improved
> > version of badblocks_set()/badblocks_clear()/badblocks_check().
> >
> > - Helpers prev_by_hint() and prev_badblocks() are used to find the bad
> >    range from bad table which the searching range starts at or after.
> >
> > - The following helpers are to decide the relative layout between the
> >    manipulating range and existing bad block range from bad table.
> >    - can_merge_behind()
> >      Return 'true' if the manipulating range can backward merge with the
> >      bad block range.
> >    - can_merge_front()
> >      Return 'true' if the manipulating range can forward merge with the
> >      bad block range.
> >    - can_combine_front()
> >      Return 'true' if two adjacent bad block ranges before the
> >      manipulating range can be merged.
> >    - overlap_front()
> >      Return 'true' if the manipulating range exactly overlaps with the
> >      bad block range in front of its range.
> >    - overlap_behind()
> >      Return 'true' if the manipulating range exactly overlaps with the
> >      bad block range behind its range.
> >    - can_front_overwrite()
> >      Return 'true' if the manipulating range can forward overwrite the
> >      bad block range in front of its range.
> >
> > - The following helpers are to add the manipulating range into the bad
> >    block table. Different routine is called with the specific relative
> >    layout between the maniplating range and other bad block range in the
> >    bad block table.
> >    - behind_merge()
> >      Merge the maniplating range with the bad block range behind its
> >      range, and return the number of merged length in unit of sector.
> >    - front_merge()
> >      Merge the maniplating range with the bad block range in front of
> >      its range, and return the number of merged length in unit of 
> > sector.
> >    - front_combine()
> >      Combine the two adjacent bad block ranges before the manipulating
> >      range into a larger one.
> >    - front_overwrite()
> >      Overwrite partial of whole bad block range which is in front of the
> >      manipulating range. The overwrite may split existing bad block 
> > range
> >      and generate more bad block ranges into the bad block table.
> >    - insert_at()
> >      Insert the manipulating range at a specific location in the bad
> >      block table.
> >
> > All the above helpers are used in later patches to improve the bad block
> > ranges handling for badblocks_set()/badblocks_clear()/badblocks_check().
> >
> > Signed-off-by: Coly Li <colyli@xxxxxxx>
> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> > Cc: Hannes Reinecke <hare@xxxxxxx>
> > Cc: Jens Axboe <axboe@xxxxxxxxx>
> > Cc: NeilBrown <neilb@xxxxxxx>
> > Cc: Richard Fan <richard.fan@xxxxxxxx>
> > Cc: Vishal L Verma <vishal.l.verma@xxxxxxxxx>
> > ---
> >   block/badblocks.c | 374 ++++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 374 insertions(+)
> >
> > diff --git a/block/badblocks.c b/block/badblocks.c
> > index d39056630d9c..efe316181e05 100644
> > --- a/block/badblocks.c
> > +++ b/block/badblocks.c
> > @@ -16,6 +16,380 @@
> >   #include <linux/types.h>
> >   #include <linux/slab.h>
> >   +/*
> > + * Find the range starts at-or-before 's' from bad table. The search
> > + * starts from index 'hint' and stops at index 'hint_end' from the bad
> > + * table.
> > + */
> > +static int prev_by_hint(struct badblocks *bb, sector_t s, int hint)
> > +{
> > +    u64 *p = bb->page;
> > +    int ret = -1;
> > +    int hint_end = hint + 2;
>
> How about declaring these variables following the "reverse Xmas tree" 
> order.

It makes sense. I will do this in whole set for next version.

Thanks for your review.

Coly Li