| Message ID | 1386802966-15531-2-git-send-email-josh.durgin@inktank.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 11 Dec 2013, Josh Durgin wrote: > The PAUSEWR and PAUSERD flags are meant to stop the cluster from > processing writes and reads, respectively. The FULL flag is set when > the cluster determines that it is out of space, and will no longer > process writes. PAUSEWR and PAUSERD are purely client-side settings > already implemented in userspace clients. The osd does nothing special > with these flags. > > When the FULL flag is set, however, the osd responds to all writes > with -ENOSPC. For cephfs, this makes sense, but for rbd the block > layer translates this into EIO. If a cluster goes from full to > non-full quickly, a filesystem on top of rbd will not behave well, > since some writes succeed while others get EIO. > > Fix this by blocking any writes when the FULL flag is set in the osd > client. This is the same strategy used by userspace, so apply it by > default. A follow-on patch makes this configurable. > > __map_request() is called to re-target osd requests in case the > available osds changed. Add a paused field to a ceph_osd_request, and > set it whenever an appropriate osd map flag is set. Avoid queueing > paused requests in __map_request(), but force them to be resent if > they become unpaused. > > Also subscribe to the next osd map from the monitor if any of these > flags are set, so paused requests can be unblocked as soon as > possible. > > Fixes: http://tracker.ceph.com/issues/6079 > > Signed-off-by: Josh Durgin <josh.durgin@inktank.com> > --- > include/linux/ceph/osd_client.h | 1 + > net/ceph/osd_client.c | 29 +++++++++++++++++++++++++++-- > 2 files changed, 28 insertions(+), 2 deletions(-) > > diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h > index 8f47625..4fb6a89 100644 > --- a/include/linux/ceph/osd_client.h > +++ b/include/linux/ceph/osd_client.h > @@ -138,6 +138,7 @@ struct ceph_osd_request { > __le64 *r_request_pool; > void *r_request_pgid; > __le32 *r_request_attempts; > + bool r_paused; > struct ceph_eversion *r_request_reassert_version; > > int r_result; > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c > index a17eaae..1ad9866 100644 > --- a/net/ceph/osd_client.c > +++ b/net/ceph/osd_client.c > @@ -1232,6 +1232,22 @@ void ceph_osdc_set_request_linger(struct ceph_osd_client *osdc, > EXPORT_SYMBOL(ceph_osdc_set_request_linger); > > /* > + * Returns whether a request should be blocked from being sent > + * based on the current osdmap and osd_client settings. > + * > + * Caller should hold map_sem for read. > + */ > +static bool __req_should_be_paused(struct ceph_osd_client *osdc, > + struct ceph_osd_request *req) > +{ > + bool pauserd = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD); > + bool pausewr = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR) || > + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL); > + return (req->r_flags & CEPH_OSD_FLAG_READ && pauserd) || > + (req->r_flags & CEPH_OSD_FLAG_WRITE && pausewr); > +} > + > +/* > * Pick an osd (the first 'up' osd in the pg), allocate the osd struct > * (as needed), and set the request r_osd appropriately. If there is > * no up osd, set r_osd to NULL. Move the request to the appropriate list > @@ -1248,6 +1264,7 @@ static int __map_request(struct ceph_osd_client *osdc, > int acting[CEPH_PG_MAX_SIZE]; > int o = -1, num = 0; > int err; > + bool was_paused; > > dout("map_request %p tid %lld\n", req, req->r_tid); > err = ceph_calc_ceph_pg(&pgid, req->r_oid, osdc->osdmap, > @@ -1264,12 +1281,18 @@ static int __map_request(struct ceph_osd_client *osdc, > num = err; > } > > + was_paused = req->r_paused; > + req->r_paused = __req_should_be_paused(osdc, req); > + if (was_paused && !req->r_paused) > + force_resend = 1; > + > if ((!force_resend && > req->r_osd && req->r_osd->o_osd == o && > req->r_sent >= req->r_osd->o_incarnation && > req->r_num_pg_osds == num && > memcmp(req->r_pg_osds, acting, sizeof(acting[0])*num) == 0) || > - (req->r_osd == NULL && o == -1)) > + (req->r_osd == NULL && o == -1) || > + req->r_paused) It seems like we could be a bit more aggressive (and more closely aligned with what the other causes of changed mappings do) and cancel the request if it is newly paused. Otherwise, we leave req->r_osd set to the last person we sent the request to, which means we might get a reply. I guess that is what we want, actually... > return 0; /* no change */ > > dout("map_request tid %llu pgid %lld.%x osd%d (was osd%d)\n", > @@ -1811,7 +1834,9 @@ done: > * we find out when we are no longer full and stop returning > * ENOSPC. > */ > - if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL)) > + if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) || > + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD) || > + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR)) > ceph_monc_request_next_osdmap(&osdc->client->monc); > > mutex_lock(&osdc->request_mutex); > -- > 1.7.10.4 > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h index 8f47625..4fb6a89 100644 --- a/include/linux/ceph/osd_client.h +++ b/include/linux/ceph/osd_client.h @@ -138,6 +138,7 @@ struct ceph_osd_request { __le64 *r_request_pool; void *r_request_pgid; __le32 *r_request_attempts; + bool r_paused; struct ceph_eversion *r_request_reassert_version; int r_result; diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index a17eaae..1ad9866 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -1232,6 +1232,22 @@ void ceph_osdc_set_request_linger(struct ceph_osd_client *osdc, EXPORT_SYMBOL(ceph_osdc_set_request_linger); /* + * Returns whether a request should be blocked from being sent + * based on the current osdmap and osd_client settings. + * + * Caller should hold map_sem for read. + */ +static bool __req_should_be_paused(struct ceph_osd_client *osdc, + struct ceph_osd_request *req) +{ + bool pauserd = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD); + bool pausewr = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR) || + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL); + return (req->r_flags & CEPH_OSD_FLAG_READ && pauserd) || + (req->r_flags & CEPH_OSD_FLAG_WRITE && pausewr); +} + +/* * Pick an osd (the first 'up' osd in the pg), allocate the osd struct * (as needed), and set the request r_osd appropriately. If there is * no up osd, set r_osd to NULL. Move the request to the appropriate list @@ -1248,6 +1264,7 @@ static int __map_request(struct ceph_osd_client *osdc, int acting[CEPH_PG_MAX_SIZE]; int o = -1, num = 0; int err; + bool was_paused; dout("map_request %p tid %lld\n", req, req->r_tid); err = ceph_calc_ceph_pg(&pgid, req->r_oid, osdc->osdmap, @@ -1264,12 +1281,18 @@ static int __map_request(struct ceph_osd_client *osdc, num = err; } + was_paused = req->r_paused; + req->r_paused = __req_should_be_paused(osdc, req); + if (was_paused && !req->r_paused) + force_resend = 1; + if ((!force_resend && req->r_osd && req->r_osd->o_osd == o && req->r_sent >= req->r_osd->o_incarnation && req->r_num_pg_osds == num && memcmp(req->r_pg_osds, acting, sizeof(acting[0])*num) == 0) || - (req->r_osd == NULL && o == -1)) + (req->r_osd == NULL && o == -1) || + req->r_paused) return 0; /* no change */ dout("map_request tid %llu pgid %lld.%x osd%d (was osd%d)\n", @@ -1811,7 +1834,9 @@ done: * we find out when we are no longer full and stop returning * ENOSPC. */ - if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL)) + if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) || + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD) || + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR)) ceph_monc_request_next_osdmap(&osdc->client->monc); mutex_lock(&osdc->request_mutex);
The PAUSEWR and PAUSERD flags are meant to stop the cluster from processing writes and reads, respectively. The FULL flag is set when the cluster determines that it is out of space, and will no longer process writes. PAUSEWR and PAUSERD are purely client-side settings already implemented in userspace clients. The osd does nothing special with these flags. When the FULL flag is set, however, the osd responds to all writes with -ENOSPC. For cephfs, this makes sense, but for rbd the block layer translates this into EIO. If a cluster goes from full to non-full quickly, a filesystem on top of rbd will not behave well, since some writes succeed while others get EIO. Fix this by blocking any writes when the FULL flag is set in the osd client. This is the same strategy used by userspace, so apply it by default. A follow-on patch makes this configurable. __map_request() is called to re-target osd requests in case the available osds changed. Add a paused field to a ceph_osd_request, and set it whenever an appropriate osd map flag is set. Avoid queueing paused requests in __map_request(), but force them to be resent if they become unpaused. Also subscribe to the next osd map from the monitor if any of these flags are set, so paused requests can be unblocked as soon as possible. Fixes: http://tracker.ceph.com/issues/6079 Signed-off-by: Josh Durgin <josh.durgin@inktank.com> --- include/linux/ceph/osd_client.h | 1 + net/ceph/osd_client.c | 29 +++++++++++++++++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-)