On Tue, Jun 03, 2025 at 12:54:05PM -0600, Jens Axboe wrote: > On 6/3/25 12:47 PM, Caleb Sander Mateos wrote: > > blk_rq_integrity_map_user() creates the ubuf iter with ITER_DEST for > > write-direction operations and ITER_SOURCE for read-direction ones. > > This is backwards; writes use the user buffer as a source for metadata > > and reads use it as a destination. Switch to the rq_data_dir() helper, > > which maps writes to ITER_SOURCE (WRITE) and reads to ITER_DEST(READ). > > Was going to ask "how did this ever work without splats", but looks like > a fairly recent change AND it's for integrity which isn't widely used. > But it does show a gap in testing for sure. The change is good and correct, but it doesn't look like normal tests would find a problem here. The iter direction in this path only adds the FOLL_WRITE flag, which appears to just check for writable access. Unless you're specifically testing something using read-only PTE's, a test wouldn't have triggered an early error. ?
