| Message ID | 20210729180442.177399-1-jlayton@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] ceph: dump info about cap flushes when we're waiting too long for them | expand |
Jeff Layton <jlayton@kernel.org> writes: > We've had some cases of hung umounts in teuthology testing. It looks > like client is waiting for cap flushes to complete, but they aren't. > > Add a field to the inode to track the highest cap flush tid seen for > that inode. Also, add a backpointer to the inode to the ceph_cap_flush > struct. > > Change wait_caps_flush to wait 60s, and then dump info about the > condition of the list. > > Also, print pr_info messages if we end up dropping a FLUSH_ACK for an > inode onto the floor. > > Reported-by: Patrick Donnelly <pdonnell@redhat.com> > URL: https://tracker.ceph.com/issues/51279 > Signed-off-by: Jeff Layton <jlayton@kernel.org> > --- > fs/ceph/caps.c | 17 +++++++++++++++-- > fs/ceph/inode.c | 1 + > fs/ceph/mds_client.c | 31 +++++++++++++++++++++++++++++-- > fs/ceph/super.h | 2 ++ > 4 files changed, 47 insertions(+), 4 deletions(-) > > v3: more debugging has shown the client waiting on FLUSH_ACK messages > that seem to never have come. Add some new printks if we end up > dropping a FLUSH_ACK onto the floor. Since you're adding debug printks, would it be worth to also add one in mds_dispatch(), when __verify_registered_session(mdsc, s) < 0? It's a wild guess, but the FLUSH_ACK could be dropped in that case too. Not that I could spot any issue there, but since this seems to be happening during umount... Cheers, -- Luis > > diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c > index 7ae83d06d48c..cb551c9e5867 100644 > --- a/fs/ceph/caps.c > +++ b/fs/ceph/caps.c > @@ -1829,6 +1829,7 @@ static u64 __mark_caps_flushing(struct inode *inode, > swap(cf, ci->i_prealloc_cap_flush); > cf->caps = flushing; > cf->wake = wake; > + cf->ci = ci; > > spin_lock(&mdsc->cap_dirty_lock); > list_del_init(&ci->i_dirty_item); > @@ -3588,6 +3589,10 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid, > bool wake_ci = false; > bool wake_mdsc = false; > > + /* track latest cap flush ack seen for this inode */ > + if (flush_tid > ci->i_last_cap_flush_ack) > + ci->i_last_cap_flush_ack = flush_tid; > + > list_for_each_entry_safe(cf, tmp_cf, &ci->i_cap_flush_list, i_list) { > /* Is this the one that was flushed? */ > if (cf->tid == flush_tid) > @@ -4116,7 +4121,11 @@ void ceph_handle_caps(struct ceph_mds_session *session, > (unsigned)seq); > > if (!inode) { > - dout(" i don't have ino %llx\n", vino.ino); > + if (op == CEPH_CAP_OP_FLUSH_ACK) > + pr_info("%s: can't find ino %llx:%llx for flush_ack!\n", > + __func__, vino.snap, vino.ino); > + else > + dout(" i don't have ino %llx\n", vino.ino); > > if (op == CEPH_CAP_OP_IMPORT) { > cap = ceph_get_cap(mdsc, NULL); > @@ -4169,10 +4178,14 @@ void ceph_handle_caps(struct ceph_mds_session *session, > spin_lock(&ci->i_ceph_lock); > cap = __get_cap_for_mds(ceph_inode(inode), session->s_mds); > if (!cap) { > - dout(" no cap on %p ino %llx.%llx from mds%d\n", > + dout(" no cap on %p ino %llx:%llx from mds%d\n", > inode, ceph_ino(inode), ceph_snap(inode), > session->s_mds); > spin_unlock(&ci->i_ceph_lock); > + if (op == CEPH_CAP_OP_FLUSH_ACK) > + pr_info("%s: no cap on %p ino %llx:%llx from mds%d for flush_ack!\n", > + __func__, inode, ceph_ino(inode), > + ceph_snap(inode), session->s_mds); > goto flush_cap_releases; > } > > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c > index 1bd2cc015913..84e4f112fc45 100644 > --- a/fs/ceph/inode.c > +++ b/fs/ceph/inode.c > @@ -499,6 +499,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb) > INIT_LIST_HEAD(&ci->i_cap_snaps); > ci->i_head_snapc = NULL; > ci->i_snap_caps = 0; > + ci->i_last_cap_flush_ack = 0; > > ci->i_last_rd = ci->i_last_wr = jiffies - 3600 * HZ; > for (i = 0; i < CEPH_FILE_MODE_BITS; i++) > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c > index c3fa0c0e4f6c..fc26527b8059 100644 > --- a/fs/ceph/mds_client.c > +++ b/fs/ceph/mds_client.c > @@ -2064,6 +2064,24 @@ static int check_caps_flush(struct ceph_mds_client *mdsc, > return ret; > } > > +static void dump_cap_flushes(struct ceph_mds_client *mdsc, u64 want_tid) > +{ > + struct ceph_cap_flush *cf; > + > + pr_info("%s: still waiting for cap flushes through %llu\n:\n", > + __func__, want_tid); > + spin_lock(&mdsc->cap_dirty_lock); > + list_for_each_entry(cf, &mdsc->cap_flush_list, g_list) { > + if (cf->tid > want_tid) > + break; > + pr_info("%llx:%llx %s %llu %llu %d\n", > + ceph_vinop(&cf->ci->vfs_inode), > + ceph_cap_string(cf->caps), cf->tid, > + cf->ci->i_last_cap_flush_ack, cf->wake); > + } > + spin_unlock(&mdsc->cap_dirty_lock); > +} > + > /* > * flush all dirty inode data to disk. > * > @@ -2072,10 +2090,19 @@ static int check_caps_flush(struct ceph_mds_client *mdsc, > static void wait_caps_flush(struct ceph_mds_client *mdsc, > u64 want_flush_tid) > { > + long ret; > + > dout("check_caps_flush want %llu\n", want_flush_tid); > > - wait_event(mdsc->cap_flushing_wq, > - check_caps_flush(mdsc, want_flush_tid)); > + do { > + ret = wait_event_timeout(mdsc->cap_flushing_wq, > + check_caps_flush(mdsc, want_flush_tid), 60 * HZ); > + if (ret == 0) > + dump_cap_flushes(mdsc, want_flush_tid); > + else if (ret == 1) > + pr_info("%s: condition evaluated to true after timeout!\n", > + __func__); > + } while (ret == 0); > > dout("check_caps_flush ok, flushed thru %llu\n", want_flush_tid); > } > diff --git a/fs/ceph/super.h b/fs/ceph/super.h > index 07eb542efa1d..d51d42a00f33 100644 > --- a/fs/ceph/super.h > +++ b/fs/ceph/super.h > @@ -189,6 +189,7 @@ struct ceph_cap_flush { > bool wake; /* wake up flush waiters when finish ? */ > struct list_head g_list; // global > struct list_head i_list; // per inode > + struct ceph_inode_info *ci; > }; > > /* > @@ -388,6 +389,7 @@ struct ceph_inode_info { > struct ceph_snap_context *i_head_snapc; /* set if wr_buffer_head > 0 or > dirty|flushing caps */ > unsigned i_snap_caps; /* cap bits for snapped files */ > + u64 i_last_cap_flush_ack; /* latest cap flush_ack tid for this inode */ > > unsigned long i_last_rd; > unsigned long i_last_wr; > -- > > 2.31.1 >
On Fri, 2021-07-30 at 11:09 +0100, Luis Henriques wrote: > Jeff Layton <jlayton@kernel.org> writes: > > > We've had some cases of hung umounts in teuthology testing. It looks > > like client is waiting for cap flushes to complete, but they aren't. > > > > Add a field to the inode to track the highest cap flush tid seen for > > that inode. Also, add a backpointer to the inode to the ceph_cap_flush > > struct. > > > > Change wait_caps_flush to wait 60s, and then dump info about the > > condition of the list. > > > > Also, print pr_info messages if we end up dropping a FLUSH_ACK for an > > inode onto the floor. > > > > Reported-by: Patrick Donnelly <pdonnell@redhat.com> > > URL: https://tracker.ceph.com/issues/51279 > > Signed-off-by: Jeff Layton <jlayton@kernel.org> > > --- > > fs/ceph/caps.c | 17 +++++++++++++++-- > > fs/ceph/inode.c | 1 + > > fs/ceph/mds_client.c | 31 +++++++++++++++++++++++++++++-- > > fs/ceph/super.h | 2 ++ > > 4 files changed, 47 insertions(+), 4 deletions(-) > > > > v3: more debugging has shown the client waiting on FLUSH_ACK messages > > that seem to never have come. Add some new printks if we end up > > dropping a FLUSH_ACK onto the floor. > > Since you're adding debug printks, would it be worth to also add one in > mds_dispatch(), when __verify_registered_session(mdsc, s) < 0? > > It's a wild guess, but the FLUSH_ACK could be dropped in that case too. > Not that I could spot any issue there, but since this seems to be > happening during umount... > > Cheers, Good point. I had looked at that case and had sort of dismissed it in this situation, but you're probably right. I've added a similar pr_info for that case and pushed it to the repo after a little testing here. I won't bother re-posting it though since the change is trivial. Thanks, -- Jeff Layton <jlayton@kernel.org>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 7ae83d06d48c..cb551c9e5867 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1829,6 +1829,7 @@ static u64 __mark_caps_flushing(struct inode *inode, swap(cf, ci->i_prealloc_cap_flush); cf->caps = flushing; cf->wake = wake; + cf->ci = ci; spin_lock(&mdsc->cap_dirty_lock); list_del_init(&ci->i_dirty_item); @@ -3588,6 +3589,10 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid, bool wake_ci = false; bool wake_mdsc = false; + /* track latest cap flush ack seen for this inode */ + if (flush_tid > ci->i_last_cap_flush_ack) + ci->i_last_cap_flush_ack = flush_tid; + list_for_each_entry_safe(cf, tmp_cf, &ci->i_cap_flush_list, i_list) { /* Is this the one that was flushed? */ if (cf->tid == flush_tid) @@ -4116,7 +4121,11 @@ void ceph_handle_caps(struct ceph_mds_session *session, (unsigned)seq); if (!inode) { - dout(" i don't have ino %llx\n", vino.ino); + if (op == CEPH_CAP_OP_FLUSH_ACK) + pr_info("%s: can't find ino %llx:%llx for flush_ack!\n", + __func__, vino.snap, vino.ino); + else + dout(" i don't have ino %llx\n", vino.ino); if (op == CEPH_CAP_OP_IMPORT) { cap = ceph_get_cap(mdsc, NULL); @@ -4169,10 +4178,14 @@ void ceph_handle_caps(struct ceph_mds_session *session, spin_lock(&ci->i_ceph_lock); cap = __get_cap_for_mds(ceph_inode(inode), session->s_mds); if (!cap) { - dout(" no cap on %p ino %llx.%llx from mds%d\n", + dout(" no cap on %p ino %llx:%llx from mds%d\n", inode, ceph_ino(inode), ceph_snap(inode), session->s_mds); spin_unlock(&ci->i_ceph_lock); + if (op == CEPH_CAP_OP_FLUSH_ACK) + pr_info("%s: no cap on %p ino %llx:%llx from mds%d for flush_ack!\n", + __func__, inode, ceph_ino(inode), + ceph_snap(inode), session->s_mds); goto flush_cap_releases; } diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index 1bd2cc015913..84e4f112fc45 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -499,6 +499,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb) INIT_LIST_HEAD(&ci->i_cap_snaps); ci->i_head_snapc = NULL; ci->i_snap_caps = 0; + ci->i_last_cap_flush_ack = 0; ci->i_last_rd = ci->i_last_wr = jiffies - 3600 * HZ; for (i = 0; i < CEPH_FILE_MODE_BITS; i++) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index c3fa0c0e4f6c..fc26527b8059 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2064,6 +2064,24 @@ static int check_caps_flush(struct ceph_mds_client *mdsc, return ret; } +static void dump_cap_flushes(struct ceph_mds_client *mdsc, u64 want_tid) +{ + struct ceph_cap_flush *cf; + + pr_info("%s: still waiting for cap flushes through %llu\n:\n", + __func__, want_tid); + spin_lock(&mdsc->cap_dirty_lock); + list_for_each_entry(cf, &mdsc->cap_flush_list, g_list) { + if (cf->tid > want_tid) + break; + pr_info("%llx:%llx %s %llu %llu %d\n", + ceph_vinop(&cf->ci->vfs_inode), + ceph_cap_string(cf->caps), cf->tid, + cf->ci->i_last_cap_flush_ack, cf->wake); + } + spin_unlock(&mdsc->cap_dirty_lock); +} + /* * flush all dirty inode data to disk. * @@ -2072,10 +2090,19 @@ static int check_caps_flush(struct ceph_mds_client *mdsc, static void wait_caps_flush(struct ceph_mds_client *mdsc, u64 want_flush_tid) { + long ret; + dout("check_caps_flush want %llu\n", want_flush_tid); - wait_event(mdsc->cap_flushing_wq, - check_caps_flush(mdsc, want_flush_tid)); + do { + ret = wait_event_timeout(mdsc->cap_flushing_wq, + check_caps_flush(mdsc, want_flush_tid), 60 * HZ); + if (ret == 0) + dump_cap_flushes(mdsc, want_flush_tid); + else if (ret == 1) + pr_info("%s: condition evaluated to true after timeout!\n", + __func__); + } while (ret == 0); dout("check_caps_flush ok, flushed thru %llu\n", want_flush_tid); } diff --git a/fs/ceph/super.h b/fs/ceph/super.h index 07eb542efa1d..d51d42a00f33 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -189,6 +189,7 @@ struct ceph_cap_flush { bool wake; /* wake up flush waiters when finish ? */ struct list_head g_list; // global struct list_head i_list; // per inode + struct ceph_inode_info *ci; }; /* @@ -388,6 +389,7 @@ struct ceph_inode_info { struct ceph_snap_context *i_head_snapc; /* set if wr_buffer_head > 0 or dirty|flushing caps */ unsigned i_snap_caps; /* cap bits for snapped files */ + u64 i_last_cap_flush_ack; /* latest cap flush_ack tid for this inode */ unsigned long i_last_rd; unsigned long i_last_wr;
We've had some cases of hung umounts in teuthology testing. It looks like client is waiting for cap flushes to complete, but they aren't. Add a field to the inode to track the highest cap flush tid seen for that inode. Also, add a backpointer to the inode to the ceph_cap_flush struct. Change wait_caps_flush to wait 60s, and then dump info about the condition of the list. Also, print pr_info messages if we end up dropping a FLUSH_ACK for an inode onto the floor. Reported-by: Patrick Donnelly <pdonnell@redhat.com> URL: https://tracker.ceph.com/issues/51279 Signed-off-by: Jeff Layton <jlayton@kernel.org> --- fs/ceph/caps.c | 17 +++++++++++++++-- fs/ceph/inode.c | 1 + fs/ceph/mds_client.c | 31 +++++++++++++++++++++++++++++-- fs/ceph/super.h | 2 ++ 4 files changed, 47 insertions(+), 4 deletions(-) v3: more debugging has shown the client waiting on FLUSH_ACK messages that seem to never have come. Add some new printks if we end up dropping a FLUSH_ACK onto the floor.