On Tue, Oct 13, 2015 at 9:27 AM, Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote: > On Tue, Oct 13, 2015 at 8:26 AM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote: >> >> On Mon, Oct 12, 2015 at 11:47 PM, Trond Myklebust >> <trond.myklebust@xxxxxxxxxxxxxxx> wrote: >> > On Mon, Oct 12, 2015 at 5:55 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote: >> >> It'll be nice to know when we return delegations synchronously or not. >> > >> > Why? This patch forces us to carry an otherwise completely unnecessary >> > parameter, so at the very minimum we should have a discussion of what >> > the real use cases are. >> >> I used it to diagnose the race of open and delegreturn. If it's kept > > How were you using it? I added two more traces points in the beginning of delegreturn and in nfs4_do_open before sending the rpc. I can see that a given file handle: -- delegreturn prepare tracepoint is happening, -- then the tracepoint of before sending the open is logged, -- then delegreturn prepare is logged again, -- then tracepoint for nfs4_open_file which is after receiving reply to the open from the server -- then delegreturn_exit tracepoint kworker/1:0H-14168 [001] .... 576.571636: nfs4_delegreturn_prepare: error=0 (OK) dev=00:2a fhandle=0x84792ca9 issync=0 hammer-13955 [000] .... 576.942632: nfs4_open_file_begin: flags=32768 (0x8000) fmode=READ|0x801c fileid=00:2a:0 fhandle=0x00000000 name=00:2a:904/000002CB.ham hammer-13955 [001] .... 577.043084: nfs4_open_file: error=0 (OK) flags=32768 (0x8000) fmode=READ|0x801c fileid=00:2a:7708 fhandle=0x84792ca9 name=00:2a:904/000002CB.ham kworker/0:1H-431 [000] .... 577.064013: nfs4_delegreturn_prepare: error=0 (OK) dev=00:2a fhandle=0x84792ca9 issync=0 kworker/0:1H-431 [000] .... 577.101076: nfs4_delegreturn_exit: error=0 (OK) dev=00:2a fhandle=0x84792ca9 kworker/0:1H-431 [000] .... 577.113021: nfs4_read: error=-10025 (BAD_STATEID) fileid=00:2a:7708 fhandle=0x84792ca9 offset=0 count=64 > >> that some delegreturns are synchronous and others are not I think the >> information is useful. > > The only difference between synchronous and asynchronous in this case > is whether or not the process that launched the delegreturn actually > waits for it to complete; a signal could easily prevent it from doing > so without interrupting the delegreturn call itself. > IOW: for complete information when debugging races here, you really > need to examine the return value from the wait call. > >> Speaking of there is a race between state manager thread returning >> used delegations and new open. Previously I thought it was evict >> inode... > > Is this with commit 5e99b532bb95 ("nfs4: reset states to use > open_stateid when returning delegation voluntarily") applied? No I have not. I will try that. Thanks. -- 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