Re: [PATCH v2 07/14] fs: iomap: Sub-extent zeroing

John Garry
2024-03-07T11:51:24Z

On 06/03/2024 21:14, Dave Chinner wrote:
>> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
>> index bcd3f8cf5ea4..733f83f839b6 100644
>> --- a/fs/iomap/direct-io.c
>> +++ b/fs/iomap/direct-io.c
>> @@ -277,7 +277,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>> {
>> const struct iomap *iomap = &iter->iomap;
>> struct inode *inode = iter->inode;
>> - unsigned int fs_block_size = i_blocksize(inode), pad;
>> + unsigned int zeroing_size, pad;
>> loff_t length = iomap_length(iter);
>> loff_t pos = iter->pos;
>> blk_opf_t bio_opf;
>> @@ -288,6 +288,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>> size_t copied = 0;
>> size_t orig_count;
>>
>> + zeroing_size = i_blocksize(inode) << iomap->extent_shift;
> The iomap interfaces use units of bytes for offsets, sizes, ranges,
> etc. Using shifts to define a granularity value seems like a
> throwback to decades old XFS code and just a bit weird nowdays. Can
> we just pass this as a byte count? i.e.:
>
> zeroing_size = i_blocksize(inode);
> if (iomap->extent_size)
> zeroing_size = iomap->extent_size;

Fine

I was also thinking of something like i_extentsize() for vfs, which
would save requiring adding iomap->extent_size, but decided to limit vfs
changes.

Thanks,
John