Re: [Devel] [PATCH rh7] cbt: blk_cbt_update_size() must return if cbt->block_max not changed

[Dmitry Monakhov]

Maxim Patlasov  writes:

> It's useless to recreate cbt every time as we called for the same
> block-device size. Actually, it's worthy only if cbt->block_max
> increases.
>
> Since commit b8e560a299 (fix cbt->block_max calculation), we calculate
> cbt->block_max precisely:
>
>>   cbt->block_max  = (size + blocksize - 1) >> cbt->block_bits;
>
> Hence, the following check:
>
>   if ((new_sz + bsz) >> cbt->block_bits <= cbt->block_max)
>   goto err_mtx;
>
> must be corrected accordingly.
>
ACK
> Signed-off-by: Maxim Patlasov 
> ---
>  block/blk-cbt.c |2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/blk-cbt.c b/block/blk-cbt.c
> index 3a2b197..4f2ce26 100644
> --- a/block/blk-cbt.c
> +++ b/block/blk-cbt.c
> @@ -440,7 +440,7 @@ void blk_cbt_update_size(struct block_device *bdev)
>   return;
>   }
>   bsz = 1 << cbt->block_bits;
> - if ((new_sz + bsz) >> cbt->block_bits <= cbt->block_max)
> + if ((new_sz + bsz - 1) >> cbt->block_bits <= cbt->block_max)
>   goto err_mtx;
>  
>   new = do_cbt_alloc(q, cbt->uuid, new_sz, bsz);


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[Devel] [PATCH rh7] cbt: blk_cbt_update_size() must return if cbt->block_max not changed

[Maxim Patlasov]

It's useless to recreate cbt every time as we called for the same
block-device size. Actually, it's worthy only if cbt->block_max
increases.

Since commit b8e560a299 (fix cbt->block_max calculation), we calculate
cbt->block_max precisely:

>   cbt->block_max  = (size + blocksize - 1) >> cbt->block_bits;

Hence, the following check:

if ((new_sz + bsz) >> cbt->block_bits <= cbt->block_max)
goto err_mtx;

must be corrected accordingly.

Signed-off-by: Maxim Patlasov 
---
 block/blk-cbt.c |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-cbt.c b/block/blk-cbt.c
index 3a2b197..4f2ce26 100644
--- a/block/blk-cbt.c
+++ b/block/blk-cbt.c
@@ -440,7 +440,7 @@ void blk_cbt_update_size(struct block_device *bdev)
return;
}
bsz = 1 << cbt->block_bits;
-   if ((new_sz + bsz) >> cbt->block_bits <= cbt->block_max)
+   if ((new_sz + bsz - 1) >> cbt->block_bits <= cbt->block_max)
goto err_mtx;
 
new = do_cbt_alloc(q, cbt->uuid, new_sz, bsz);

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