linux-kernel - Re: [PATCH 3/4] bitmap: Introduce bitmap

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Date:   Sun, 3 Jul 2022 08:50:19 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Yury Norov <yury.norov@...il.com>
Cc:     agk@...hat.com, snitzer@...nel.org, dm-devel@...hat.com,
        vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, hca@...ux.ibm.com,
        gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
        almaz.alexandrovich@...agon-software.com,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk,
        linux-s390@...r.kernel.org, ntfs3@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 3/4] bitmap: Introduce bitmap_size()

Le 02/07/2022 à 23:09, Yury Norov a écrit :
> On Sat, Jul 02, 2022 at 08:29:36PM +0200, Christophe JAILLET wrote:
>> The new bitmap_size() function returns the size, in bytes, of a bitmap.
>>
>> Remove the already existing bitmap_size() functions and macro in some
>> files.
>> These files already use the bitmap API and will use the new function
>> in bitmap.h automatically.
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>>   drivers/md/dm-clone-metadata.c | 5 -----
>>   include/linux/bitmap.h         | 6 ++++++
>>   lib/math/prime_numbers.c       | 2 --
>>   3 files changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/md/dm-clone-metadata.c b/drivers/md/dm-clone-metadata.c
>> index c43d55672bce..47c1fa7aad8b 100644
>> --- a/drivers/md/dm-clone-metadata.c
>> +++ b/drivers/md/dm-clone-metadata.c
>> @@ -465,11 +465,6 @@ static void __destroy_persistent_data_structures(struct dm_clone_metadata *cmd)
>>   
>>   /*---------------------------------------------------------------------------*/
>>   
>> -static size_t bitmap_size(unsigned long nr_bits)
>> -{
>> -	return BITS_TO_LONGS(nr_bits) * sizeof(long);
>> -}
>> -
>>   static int __dirty_map_init(struct dirty_map *dmap, unsigned long nr_words,
>>   			    unsigned long nr_regions)
>>   {
>> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
>> index f091a1664bf1..f66fb98a4126 100644
>> --- a/include/linux/bitmap.h
>> +++ b/include/linux/bitmap.h
>> @@ -48,6 +48,7 @@ struct device;
>>    *  bitmap_equal(src1, src2, nbits)             Are *src1 and *src2 equal?
>>    *  bitmap_intersects(src1, src2, nbits)        Do *src1 and *src2 overlap?
>>    *  bitmap_subset(src1, src2, nbits)            Is *src1 a subset of *src2?
>> + *  bitmap_size(nbits)                          Size, in bytes, of a bitmap
>>    *  bitmap_empty(src, nbits)                    Are all bits zero in *src?
>>    *  bitmap_full(src, nbits)                     Are all bits set in *src?
>>    *  bitmap_weight(src, nbits)                   Hamming Weight: number set bits
>> @@ -124,6 +125,11 @@ unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node);
>>   unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node);
>>   void bitmap_free(const unsigned long *bitmap);
>>   
>> +static __always_inline size_t bitmap_size(unsigned long nbits)
>> +{
>> +	return BITS_TO_LONGS(nbits) * sizeof(unsigned long);
>> +}
>> +
>>   /* Managed variants of the above. */
>>   unsigned long *devm_bitmap_alloc(struct device *dev,
>>   				 unsigned int nbits, gfp_t flags);
>> diff --git a/lib/math/prime_numbers.c b/lib/math/prime_numbers.c
>> index d42cebf7407f..d3b64b10da1c 100644
>> --- a/lib/math/prime_numbers.c
>> +++ b/lib/math/prime_numbers.c
>> @@ -6,8 +6,6 @@
>>   #include <linux/prime_numbers.h>
>>   #include <linux/slab.h>
>>   
>> -#define bitmap_size(nbits) (BITS_TO_LONGS(nbits) * sizeof(unsigned long))
>> -
> 
> This should be dropped, for sure, and kmalloc() at line 128 should be
> replaced with bitmap_alloc().

This kmalloc() is for a structure and a flexible array.

You mean re-arranging the code to allocate the structure alone at first, 
then the bitmap?

CJ

> 
> For the driver, we need to introduce bitmap_kvmalloc/bitmap_kvfree etc.
> 
>>   struct primes {
>>   	struct rcu_head rcu;
>>   	unsigned long last, sz;
>> -- 
>> 2.34.1
>