On Fri, Dec 08, 2017 at 05:16:26PM -0500, J. Bruce Fields wrote: > Last year Christoph noticed a bug that could result in a file being > unnecessarily sillyrenamed after O_DIRECT writes get ENOSPC: > > http://lkml.kernel.org/r/20160616150146.GA14015@xxxxxxxxxxxxx > > It's reproduceable on upstream, over v3 or v4. > > I looked into it some more, and it seems to reproduce whenever a write > system call results in multiple WRITE calls, only some of which receive > ENOSPC. I think that's resulting in a leak of the wb_kref on some > nfs_pages (possibly the ones corresponding to the ENOSPC failures?). > Those nfs_pages in turn hold references on nfs_{lock,open}_contexts. So > a "rm" on the client (even after the file is closed) results in a > sillyrename. > > I'll keep looking at this, but the relevant code is pretty opaque to me > so far. Any ideas welcomed. Actually it looks like a leak of dreq->io_count? That prevents commits from being sent (which I'm also seeing in network traces--the succesfull WRITEs are unstable but never get committed), which means nfs_direct_commit_complete() is never called, and the reference taken on wb_kref in the request_commit case of nfs_direct_write_completion is never put. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
