Re: [RFC PATCH] fs/hugetlb: Fix UBSAN warning reported on hugetlb

[Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>]

On 9/8/22 10:23 PM, Matthew Wilcox wrote:
> On Thu, Sep 08, 2022 at 12:56:59PM +0530, Aneesh Kumar K.V wrote:
>> +++ b/fs/dax.c
>> @@ -1304,7 +1304,7 @@ EXPORT_SYMBOL_GPL(dax_zero_range);
>>  int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
>>  		const struct iomap_ops *ops)
>>  {
>> -	unsigned int blocksize = i_blocksize(inode);
>> +	size_t blocksize = i_blocksize(inode);
>>  	unsigned int off = pos & (blocksize - 1);
> 
> If blocksize is larger than 4GB, then off also needs to be size_t.
> 
>> +++ b/fs/iomap/buffered-io.c
>> @@ -955,7 +955,7 @@ int
>>  iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
>>  		const struct iomap_ops *ops)
>>  {
>> -	unsigned int blocksize = i_blocksize(inode);
>> +	size_t blocksize = i_blocksize(inode);
>>  	unsigned int off = pos & (blocksize - 1);
> 
> Ditto.
> 
> (maybe there are others; I didn't check closely)

Thanks. will check those. 

Any feedback on statx? Should we really fix that?

I am still not clear why we chose to set blocksize = pagesize for hugetlbfs.
Was that done to enable application find the hugetlb pagesize via stat()? 

-aneesh