Christoph Hellwig <hch@xxxxxxxxxxxxx> writes: > On Thu, Apr 25, 2024 at 06:58:50PM +0530, Ritesh Harjani (IBM) wrote: >> iomap_readpage_iter() handles "uptodate blocks" and "not uptodate blocks" >> within a folio separately. This makes iomap_read_folio() to call into >> ->iomap_begin() to request for extent mapping even though it might already >> have an extent which is not fully processed. >> >> This happens when we either have a large folio or with bs < ps. In these >> cases we can have sub blocks which can be uptodate (say for e.g. due to >> previous writes). With iomap_read_folio_iter(), this is handled more >> efficiently by not calling ->iomap_begin() call until all the sub blocks >> with the current folio are processed. > > Maybe throw in a sentence here that this copies what > iomap_readahead_iter already does? Does this sound any better? iomap_read_folio_iter() handles multiple sub blocks within a given folio but it's implementation logic is similar to how iomap_readahead_iter() handles multiple folios within a single mapped extent. Both of them iterate over a given range of folio/mapped extent and call iomap_readpage_iter() for reading. > > Otherwise this looks good to me modulo the offset comment from willy. Yes, I will address willy's comment too. Thanks for the review! -ritesh
