On Sat, Mar 15, 2025 at 11:03:20AM -0600, Jens Axboe wrote: > On 3/15/25 11:01 AM, Kent Overstreet wrote: > > On Sat, Mar 15, 2025 at 10:47:09AM -0600, Jens Axboe wrote: > >> On 3/11/25 2:15 PM, Kent Overstreet wrote: > >>> REQ_FUA|REQ_READ means "do a read that bypasses the controller cache", > >>> the same as writes. > >>> > >>> This is useful for when the filesystem gets a checksum error, it's > >>> possible that a bit was flipped in the controller cache, and when we > >>> retry we want to retry the entire IO, not just from cache. > >>> > >>> The nvme driver already passes through REQ_FUA for reads, not just > >>> writes, so disabling the warning is sufficient to start using it, and > >>> bcachefs is implementing additional retries for checksum errors so can > >>> immediately use it. > >> > >> This one got effectively nak'ed by various folks here: > >> > >>> Link: https://lore.kernel.org/linux-block/20250311133517.3095878-1-kent.overstreet@xxxxxxxxx/ > >> > >> yet it's part of this series and in linux-next? Hmm? > > > > As I explained in that thread, they were only thinking about the caching > > of writes. > > > > That's not what we're concerned about; when we retry a read due to a > > checksum error we do not want the previous _read_ cached. > > Please follow the usual procedure of getting the patch acked/reviewed on > the block list, and go through the usual trees. Until that happens, this > patch should not be in your tree, not should it be staged in linux-next. It's been posted to linux-block and sent to your inbox. If you're going to take it that's fine, otherwise - since this is necessary for handling bitrotted data correctly and I've got users who've been waiting on this patch series, and it's just deleting a warning, I'm inclined to just send it. I'll make sure he's got the lore links and knows what's going on, but this isn't a great thing to be delaying on citing process.
