Return-Path: Received: from mail-ua0-f175.google.com ([209.85.217.175]:54994 "EHLO mail-ua0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752354AbdJIOxP (ORCPT ); Mon, 9 Oct 2017 10:53:15 -0400 Received: by mail-ua0-f175.google.com with SMTP id n38so8143705uai.11 for ; Mon, 09 Oct 2017 07:53:14 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170928183846.GG10182@parsley.fieldses.org> References: <20170928172945.50780-1-kolga@netapp.com> <20170928172945.50780-9-kolga@netapp.com> <20170928183846.GG10182@parsley.fieldses.org> From: Olga Kornievskaia Date: Mon, 9 Oct 2017 10:53:13 -0400 Message-ID: Subject: Re: [PATCH v4 08/10] NFSD handle OFFLOAD_CANCEL op To: "J. Bruce Fields" Cc: Olga Kornievskaia , linux-nfs Content-Type: text/plain; charset="UTF-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Sep 28, 2017 at 2:38 PM, J. Bruce Fields wrote: > On Thu, Sep 28, 2017 at 01:29:43PM -0400, Olga Kornievskaia wrote: >> Upon receiving OFFLOAD_CANCEL search the list of copy stateids, >> if found mark it cancelled. If copy has more interations to >> call vfs_copy_file_range, it'll stop it. Server won't be sending >> CB_OFFLOAD to the client since it received a cancel. >> >> Signed-off-by: Olga Kornievskaia >> --- >> fs/nfsd/nfs4proc.c | 26 ++++++++++++++++++++++++-- >> fs/nfsd/nfs4state.c | 16 ++++++++++++++++ >> fs/nfsd/state.h | 4 ++++ >> 3 files changed, 44 insertions(+), 2 deletions(-) >> >> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c >> index 3cddebb..f4f3d93 100644 >> --- a/fs/nfsd/nfs4proc.c >> +++ b/fs/nfsd/nfs4proc.c >> @@ -1139,6 +1139,7 @@ static int _nfsd_copy_file_range(struct nfsd4_copy *copy) >> size_t bytes_to_copy; >> u64 src_pos = copy->cp_src_pos; >> u64 dst_pos = copy->cp_dst_pos; >> + bool cancelled = false; >> >> do { >> bytes_to_copy = min_t(u64, bytes_total, MAX_RW_COUNT); >> @@ -1150,7 +1151,12 @@ static int _nfsd_copy_file_range(struct nfsd4_copy *copy) >> copy->cp_res.wr_bytes_written += bytes_copied; >> src_pos += bytes_copied; >> dst_pos += bytes_copied; >> - } while (bytes_total > 0 && !copy->cp_synchronous); >> + if (!copy->cp_synchronous) { >> + spin_lock(©->cps->cp_lock); >> + cancelled = copy->cps->cp_cancelled; >> + spin_unlock(©->cps->cp_lock); >> + } >> + } while (bytes_total > 0 && !copy->cp_synchronous && !cancelled); >> return bytes_copied; > > I'd rather we sent a signal, and then we won't need this > logic--vfs_copy_range() will just return EINTR or something. Hi Bruce, Now that I've implemented using the kthread instead of the workqueue, I don't see that it can provide any better guarantee than the work queue. vfs_copy_range() is not interrupted in the middle and returning the EINTR. The function that runs the kthread, it has to at some point call signalled()/kthread_should_stop() function to see if it was signaled and use it to 'stop working instead of continuing on'. If I were to remove the loop and check (if signaled() || kthread_should_stop()) before and after calling the vfs_copy_file_range(), the copy will either not start if the OFFLOAD_CANCEL was received before copy started or the whole copy would happen. Even with the loop, I'd be checking after every call for vfs_copy_file_range() just like it was in the current version with the workqueue. Please advise if you still want the kthread-based implementation or keep the workqueue. > That will help us get rid of the 4MB-at-a-time loop. And will mean we > don't need to wait for the next 4MB copy to finish before stopping the > loop. Normally I wouldn't expect that to take too long, but it might. > And a situation where a cancel is sent is a situation where we're > probably more likely to have some problem slowing down the copy. > > Also: don't we want OFFLOAD_CANCEL to wait until the cancel has actually > taken effect before returning? > > I can't see any language in the spec to that affect, but it would seem > surprising to me if I got back a succesful response to OFFLOAD_CANCEL > and then noticed that the target file was still changing. > > --b. > >> } >> >> @@ -1198,6 +1204,10 @@ static void nfsd4_do_async_copy(struct work_struct *work) >> struct nfsd4_copy *cb_copy; >> >> copy->nfserr = nfsd4_do_copy(copy, 0); >> + >> + if (copy->cps->cp_cancelled) >> + goto out; >> + >> cb_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL); >> if (!cb_copy) >> goto out; >> @@ -1269,7 +1279,19 @@ static void nfsd4_do_async_copy(struct work_struct *work) >> struct nfsd4_compound_state *cstate, >> union nfsd4_op_u *u) >> { >> - return 0; >> + struct nfsd4_offload_status *os = &u->offload_status; >> + struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id); >> + __be32 status; >> + struct nfs4_cp_state *state = NULL; >> + >> + status = find_cp_state(nn, &os->stateid, &state); >> + if (state) { >> + spin_lock(&state->cp_lock); >> + state->cp_cancelled = true; >> + spin_unlock(&state->cp_lock); >> + } >> + >> + return status; >> } >> >> static __be32 >> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c >> index be59baf..97ab3f8 100644 >> --- a/fs/nfsd/nfs4state.c >> +++ b/fs/nfsd/nfs4state.c >> @@ -752,6 +752,22 @@ static void nfs4_free_deleg(struct nfs4_stid *stid) >> atomic_long_dec(&num_delegations); >> } >> >> +__be32 find_cp_state(struct nfsd_net *nn, stateid_t *st, >> + struct nfs4_cp_state **cps) >> +{ >> + struct nfs4_cp_state *state = NULL; >> + >> + if (st->si_opaque.so_clid.cl_id != nn->s2s_cp_cl_id) >> + return nfserr_bad_stateid; >> + spin_lock(&nn->s2s_cp_lock); >> + state = idr_find(&nn->s2s_cp_stateids, st->si_opaque.so_id); >> + spin_unlock(&nn->s2s_cp_lock); >> + if (!state) >> + return nfserr_bad_stateid; >> + *cps = state; >> + return 0; >> +} >> + >> /* >> * When we recall a delegation, we should be careful not to hand it >> * out again straight away. >> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h >> index 8724955..7a070d5 100644 >> --- a/fs/nfsd/state.h >> +++ b/fs/nfsd/state.h >> @@ -111,6 +111,8 @@ struct nfs4_cp_state { >> stateid_t cp_stateid; >> struct list_head cp_list; /* per parent nfs4_stid */ >> struct nfs4_stid *cp_p_stid; /* pointer to parent */ >> + bool cp_cancelled; /* copy cancelled */ >> + spinlock_t cp_lock; >> }; >> >> /* >> @@ -647,6 +649,8 @@ extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name, >> extern bool nfs4_has_reclaimed_state(const char *name, struct nfsd_net *nn); >> extern int nfsd4_create_copy_queue(void); >> extern void nfsd4_destroy_copy_queue(void); >> +extern __be32 find_cp_state(struct nfsd_net *nn, stateid_t *st, >> + struct nfs4_cp_state **cps); >> >> struct nfs4_file *find_file(struct knfsd_fh *fh); >> void put_nfs4_file(struct nfs4_file *fi); >> -- >> 1.8.3.1 >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html