On Mon, 11 Aug 2025 03:41:39 -0700, Christoph Hellwig wrote:
> Where "the whole thing" is the current iteration in the write loop.
> Can you spell this out a bit better?
Hahaha, I was also confused about "the whole thing". I guess it refers to a
partial write in a folio. It appears in the comments of __iomap_write_end().
static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
size_t copied, struct folio *folio)
{
flush_dcache_folio(folio);
/*
* The blocks that were entirely written will now be uptodate, so we
* don't have to worry about a read_folio reading them and overwriting a
* partial write. However, if we've encountered a short write and only
* partially written into a block, it will not be marked uptodate, so a
* read_folio might come in and destroy our partial write.
*
* Do the simplest thing and just treat any short write to a
* non-uptodate page as a zero-length write, and force the caller to
* redo the whole thing.
^^^^^^^^^^^^^^^ <------------------ look look look, it's here :)
*/
if (unlikely(copied < len && !folio_test_uptodate(folio)))
return false;
iomap_set_range_uptodate(folio, offset_in_folio(folio, pos), len);
iomap_set_range_dirty(folio, offset_in_folio(folio, pos), copied);
filemap_dirty_folio(inode->i_mapping, folio);
return true;
}
>
> Also please include the rationale why you are changing the logic
> here in the commit log.
Hahaha, what I want to express is that we no longer need to define partial write
based on folio granularity, it is more appropriate to use block granularity.
Please forgive my poor English. :-<
thanks,
Jinliang Zheng :)
