On Fri, Feb 21, 2025 at 04:11:06PM +0800, Zheng Qixing wrote:
> From: Zheng Qixing <[email protected]>
> 
> The bad blocks check would miss bad blocks when retrying under contention,
> as checking parameters are not reset. These stale values from the previous
> attempt could lead to incorrect scanning in the subsequent retry.
> 
> Move seqlock to outer function and reinitialize checking state for each
> retry. This ensures a clean state for each check attempt, preventing any
> missed bad blocks.
> 
> Fixes: 3ea3354cb9f0 ("badblocks: improve badblocks_check() for multiple 
> ranges handling")
> Signed-off-by: Zheng Qixing <[email protected]>

Looks good to me.

Acked-by: Coly Li <[email protected]>

Thanks.

> ---
>  block/badblocks.c | 50 +++++++++++++++++++++++------------------------
>  1 file changed, 24 insertions(+), 26 deletions(-)
> 
> diff --git a/block/badblocks.c b/block/badblocks.c
> index 381f9db423d6..79d91be468c4 100644
> --- a/block/badblocks.c
> +++ b/block/badblocks.c
> @@ -1191,31 +1191,12 @@ static int _badblocks_clear(struct badblocks *bb, 
> sector_t s, int sectors)
>  static int _badblocks_check(struct badblocks *bb, sector_t s, int sectors,
>                           sector_t *first_bad, int *bad_sectors)
>  {
> -     int unacked_badblocks, acked_badblocks;
>       int prev = -1, hint = -1, set = 0;
>       struct badblocks_context bad;
> -     unsigned int seq;
> +     int unacked_badblocks = 0;
> +     int acked_badblocks = 0;
> +     u64 *p = bb->page;
>       int len, rv;
> -     u64 *p;
> -
> -     WARN_ON(bb->shift < 0 || sectors == 0);
> -
> -     if (bb->shift > 0) {
> -             sector_t target;
> -
> -             /* round the start down, and the end up */
> -             target = s + sectors;
> -             rounddown(s, 1 << bb->shift);
> -             roundup(target, 1 << bb->shift);
> -             sectors = target - s;
> -     }
> -
> -retry:
> -     seq = read_seqbegin(&bb->lock);
> -
> -     p = bb->page;
> -     unacked_badblocks = 0;
> -     acked_badblocks = 0;
>  
>  re_check:
>       bad.start = s;
> @@ -1281,9 +1262,6 @@ static int _badblocks_check(struct badblocks *bb, 
> sector_t s, int sectors,
>       else
>               rv = 0;
>  
> -     if (read_seqretry(&bb->lock, seq))
> -             goto retry;
> -
>       return rv;
>  }
>  
> @@ -1324,7 +1302,27 @@ static int _badblocks_check(struct badblocks *bb, 
> sector_t s, int sectors,
>  int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
>                       sector_t *first_bad, int *bad_sectors)
>  {
> -     return _badblocks_check(bb, s, sectors, first_bad, bad_sectors);
> +     unsigned int seq;
> +     int rv;
> +
> +     WARN_ON(bb->shift < 0 || sectors == 0);
> +
> +     if (bb->shift > 0) {
> +             /* round the start down, and the end up */
> +             sector_t target = s + sectors;
> +
> +             rounddown(s, 1 << bb->shift);
> +             roundup(target, 1 << bb->shift);
> +             sectors = target - s;
> +     }
> +
> +retry:
> +     seq = read_seqbegin(&bb->lock);
> +     rv = _badblocks_check(bb, s, sectors, first_bad, bad_sectors);
> +     if (read_seqretry(&bb->lock, seq))
> +             goto retry;
> +
> +     return rv;
>  }
>  EXPORT_SYMBOL_GPL(badblocks_check);
>  
> -- 
> 2.39.2
> 

-- 
Coly Li

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