From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Spray Subject: Re: [PATCH v8 4/7] libceph: add an epoch_barrier field to struct ceph_osd_client Date: Tue, 18 Apr 2017 13:38:58 +0100 Message-ID: References: <20170417164258.31527-1-jlayton@redhat.com> <20170417164258.31527-5-jlayton@redhat.com> <1492517978.10210.3.camel@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Return-path: Received: from mail-wm0-f45.google.com ([74.125.82.45]:33975 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753123AbdDRMjV (ORCPT ); Tue, 18 Apr 2017 08:39:21 -0400 Received: by mail-wm0-f45.google.com with SMTP id r190so9848326wme.1 for ; Tue, 18 Apr 2017 05:39:20 -0700 (PDT) In-Reply-To: <1492517978.10210.3.camel@redhat.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Jeff Layton Cc: Ilya Dryomov , =?UTF-8?B?5Lil5q2j?= , Sage Weil , Ceph Development On Tue, Apr 18, 2017 at 1:19 PM, Jeff Layton wrote: > On Mon, 2017-04-17 at 12:42 -0400, Jeff Layton wrote: >> Cephfs can get cap update requests that contain a new epoch barrier in >> them. When that happens we want to pause all OSD traffic until the right >> map epoch arrives. >> >> Add an epoch_barrier field to ceph_osd_client that is protected by the >> osdc->lock rwsem. When the barrier is set, and the current OSD map >> epoch is below that, pause the request target when submitting the >> request or when revisiting it. Add a way for upper layers (cephfs) >> to update the epoch_barrier as well. >> >> If we get a new map, compare the new epoch against the barrier before >> kicking requests and request another map if the map epoch is still lower >> than the one we want. >> >> If we get a map with a full pool, or at quota condition, then set the >> barrier to the current epoch value. >> >> Reviewed-by: "Yan, Zheng” >> Signed-off-by: Jeff Layton >> Reviewed-by: Ilya Dryomov >> --- >> include/linux/ceph/osd_client.h | 2 ++ >> net/ceph/debugfs.c | 3 +- >> net/ceph/osd_client.c | 76 ++++++++++++++++++++++++++++++++++++----- >> 3 files changed, 72 insertions(+), 9 deletions(-) >> >> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h >> index 8cf644197b1a..85650b415e73 100644 >> --- a/include/linux/ceph/osd_client.h >> +++ b/include/linux/ceph/osd_client.h >> @@ -267,6 +267,7 @@ struct ceph_osd_client { >> struct rb_root osds; /* osds */ >> struct list_head osd_lru; /* idle osds */ >> spinlock_t osd_lru_lock; >> + u32 epoch_barrier; >> struct ceph_osd homeless_osd; >> atomic64_t last_tid; /* tid of last request */ >> u64 last_linger_id; >> @@ -305,6 +306,7 @@ extern void ceph_osdc_handle_reply(struct ceph_osd_client *osdc, >> struct ceph_msg *msg); >> extern void ceph_osdc_handle_map(struct ceph_osd_client *osdc, >> struct ceph_msg *msg); >> +void ceph_osdc_update_epoch_barrier(struct ceph_osd_client *osdc, u32 eb); >> >> extern void osd_req_op_init(struct ceph_osd_request *osd_req, >> unsigned int which, u16 opcode, u32 flags); >> diff --git a/net/ceph/debugfs.c b/net/ceph/debugfs.c >> index d7e63a4f5578..71ba13927b3d 100644 >> --- a/net/ceph/debugfs.c >> +++ b/net/ceph/debugfs.c >> @@ -62,7 +62,8 @@ static int osdmap_show(struct seq_file *s, void *p) >> return 0; >> >> down_read(&osdc->lock); >> - seq_printf(s, "epoch %d flags 0x%x\n", map->epoch, map->flags); >> + seq_printf(s, "epoch %u barrier %u flags 0x%x\n", map->epoch, >> + osdc->epoch_barrier, map->flags); >> >> for (n = rb_first(&map->pg_pools); n; n = rb_next(n)) { >> struct ceph_pg_pool_info *pi = >> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c >> index 55b7585ccefd..beeac4f39aa5 100644 >> --- a/net/ceph/osd_client.c >> +++ b/net/ceph/osd_client.c >> @@ -1298,8 +1298,9 @@ static bool target_should_be_paused(struct ceph_osd_client *osdc, >> __pool_full(pi); >> >> WARN_ON(pi->id != t->base_oloc.pool); >> - return (t->flags & CEPH_OSD_FLAG_READ && pauserd) || >> - (t->flags & CEPH_OSD_FLAG_WRITE && pausewr); >> + return ((t->flags & CEPH_OSD_FLAG_READ) && pauserd) || >> + ((t->flags & CEPH_OSD_FLAG_WRITE) && pausewr) || >> + (osdc->osdmap->epoch < osdc->epoch_barrier); >> } >> >> enum calc_target_result { >> @@ -1654,8 +1655,13 @@ static void __submit_request(struct ceph_osd_request *req, bool wrlocked) >> goto promote; >> } >> >> - if ((req->r_flags & CEPH_OSD_FLAG_WRITE) && >> - ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR)) { >> + if (osdc->osdmap->epoch < osdc->epoch_barrier) { >> + dout("req %p epoch %u barrier %u\n", req, osdc->osdmap->epoch, >> + osdc->epoch_barrier); >> + req->r_t.paused = true; >> + maybe_request_map(osdc); >> + } else if ((req->r_flags & CEPH_OSD_FLAG_WRITE) && >> + ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR)) { >> dout("req %p pausewr\n", req); >> req->r_t.paused = true; >> maybe_request_map(osdc); >> @@ -1809,17 +1815,48 @@ static void abort_request(struct ceph_osd_request *req, int err) >> >> /* >> * Drop all pending requests that are stalled waiting on a full condition to >> - * clear, and complete them with ENOSPC as the return code. >> + * clear, and complete them with ENOSPC as the return code. Set the >> + * osdc->epoch_barrier to the latest map epoch that we've seen if any were >> + * cancelled. >> */ >> static void ceph_osdc_abort_on_full(struct ceph_osd_client *osdc) >> { >> struct rb_node *n; >> + bool victims = false; >> >> dout("enter abort_on_full\n"); >> >> if (!ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) && !have_pool_full(osdc)) >> goto out; >> >> + /* Scan list and see if there is anything to abort */ >> + for (n = rb_first(&osdc->osds); n; n = rb_next(n)) { >> + struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node); >> + struct rb_node *m; >> + >> + m = rb_first(&osd->o_requests); >> + while (m) { >> + struct ceph_osd_request *req = rb_entry(m, >> + struct ceph_osd_request, r_node); >> + m = rb_next(m); >> + >> + if (req->r_abort_on_full) { >> + victims = true; >> + break; >> + } >> + } >> + if (victims) >> + break; >> + } >> + >> + if (!victims) >> + goto out; >> + >> + /* >> + * Update the barrier to current epoch since we know we have some >> + * calls to be aborted in the tree. >> + */ >> + osdc->epoch_barrier = osdc->osdmap->epoch; > > Erm...now that I think about it even more... > > Is it possible we can end up with the eb going backward here? Suppose > we get a MDS cap message with a later epoch barrier, and then a map > update that is not quite to the barrier yet. > > I think we probably want to only set it if it's newer than what's > there. So this should probably read something like: > > if (osdc->osdmap->epoch > osdc->epoch_barrier) > osdc->epoch_barrier = osdc->osdmap->epoch; > > If no one objects, I'll go ahead and make this change in the testing > branch without a full re-post to the list. Yes indeed -- the userspace client does the same check inside Objecter::set_epoch_barrier. John >> for (n = rb_first(&osdc->osds); n; n = rb_next(n)) { >> struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node); >> struct rb_node *m; >> @@ -1832,12 +1869,13 @@ static void ceph_osdc_abort_on_full(struct ceph_osd_client *osdc) >> >> if (req->r_abort_on_full && >> (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) || >> - pool_full(osdc, req->r_t.target_oloc.pool))) >> + pool_full(osdc, req->r_t.target_oloc.pool))) { >> abort_request(req, -ENOSPC); >> + } >> } >> } >> out: >> - dout("return abort_on_full\n"); >> + dout("return abort_on_full barrier=%u\n", osdc->epoch_barrier); >> } >> >> static void check_pool_dne(struct ceph_osd_request *req) >> @@ -3293,7 +3331,8 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg) >> pausewr = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR) || >> ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) || >> have_pool_full(osdc); >> - if (was_pauserd || was_pausewr || pauserd || pausewr) >> + if (was_pauserd || was_pausewr || pauserd || pausewr || >> + osdc->osdmap->epoch < osdc->epoch_barrier) >> maybe_request_map(osdc); >> >> kick_requests(osdc, &need_resend, &need_resend_linger); >> @@ -3311,6 +3350,27 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg) >> up_write(&osdc->lock); >> } >> >> +void ceph_osdc_update_epoch_barrier(struct ceph_osd_client *osdc, u32 eb) >> +{ >> + down_read(&osdc->lock); >> + if (unlikely(eb > osdc->epoch_barrier)) { >> + up_read(&osdc->lock); >> + down_write(&osdc->lock); >> + if (likely(eb > osdc->epoch_barrier)) { >> + dout("updating epoch_barrier from %u to %u\n", >> + osdc->epoch_barrier, eb); >> + osdc->epoch_barrier = eb; >> + /* Request map if we're not to the barrier yet */ >> + if (eb > osdc->osdmap->epoch) >> + maybe_request_map(osdc); >> + } >> + up_write(&osdc->lock); >> + } else { >> + up_read(&osdc->lock); >> + } >> +} >> +EXPORT_SYMBOL(ceph_osdc_update_epoch_barrier); >> + >> /* >> * Resubmit requests pending on the given osd. >> */ > > -- > Jeff Layton