On Tue, Apr 18, 2017 at 2:19 PM, Jeff Layton <jlayton@xxxxxxxxxx> 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” <zyan@xxxxxxxxxx>
>> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>> Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx>
>> ---
>> 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.
I'd wrap
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);
}
from ceph_osdc_update_epoch_barrier() into update_epoch_barrier() and
call it from here.
Thanks,
Ilya
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