Re: [PATCH v2] btrfs: replace kcalloc() calls to kzalloc_objs()

["Miquel Sabaté Solà" <mssola@mssola.com>]

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David Sterba @ 2026-02-27 01:27 +01:

> On Tue, Feb 24, 2026 at 10:45:44PM +0100, Miquel Sabaté Solà wrote:
>> Commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj() and family")
>> introduced, among many others, the kzalloc_objs() helper, which has some
>> benefits over kcalloc(). Namely, internal introspection of the allocated
>> type now becomes possible, allowing for future alignment-aware choices
>> to be made by the allocator and future hardening work that can be type
>> sensitive. Dropping 'sizeof' comes also as a nice side-effect.
>>
>> Moreover, this also allows us to be in line with the recent tree-wide
>> migration to the kmalloc_obj() and family of helpers. See
>> commit 69050f8d6d07 ("treewide: Replace kmalloc with kmalloc_obj for
>> non-scalar types").
>>
>> Reviewed-by: Kees Cook <kees@kernel.org>
>> Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
>
> Added to for-next, thanks.
>
>> -	buf = kcalloc(map->num_stripes, sizeof(u64), GFP_NOFS);
>> +	buf = kzalloc_objs(*buf, map->num_stripes, GFP_NOFS);
>
>> -	pointers = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS);
>> -	unmap_array = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS);
>> +	pointers = kzalloc_objs(*pointers, rbio->real_stripes, GFP_NOFS);
>> +	unmap_array = kzalloc_objs(*unmap_array, rbio->real_stripes, GFP_NOFS);
>
>> -	pointers = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS);
>> -	unmap_array = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS);
>> +	pointers = kzalloc_objs(*pointers, rbio->real_stripes, GFP_NOFS);
>> +	unmap_array = kzalloc_objs(*unmap_array, rbio->real_stripes, GFP_NOFS);
>
> I've changed it to the type in the above cases so it's a direct
> conversion that only removes the sizeof(). For the rest there are no
> strong preferences so we'll keep it as is, and my preference for new code
> is to use the types.

Got it, thanks!

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