On Sun, Jul 26, 2020 at 10:10:52AM +0100, Matthew Wilcox (Oracle) wrote: > If the filesystem has block size < page size and we end up calling > iomap_page_create() in iomap_page_mkwrite_actor(), the uptodate bits > would be zero, which causes us to skip writeback of blocks which are > !uptodate in iomap_writepage_map(). This can lead to user data loss. > > Found using generic/127 with the THP patches. I don't think this can be > reproduced on mainline using that test (the THP code causes iomap_pages > to be discarded more frequently), but inspection shows it can happen > with an appropriate series of operations. Looks good, Reviewed-by: Christoph Hellwig <hch@xxxxxx>
