| Message ID | 20230327030508.310588-1-xiubli@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] ceph: drop the messages from MDS when unmounting | expand |
Hi! I finally got to have a look at this patch because I found that the version you sent along with fscrypt v17 is a bit different from what's in the testing branch :-) xiubli@redhat.com writes: > From: Xiubo Li <xiubli@redhat.com> > > When unmounting and all the dirty buffer will be flushed and after > the last osd request is finished the last reference of the i_count > will be released. Then it will flush the dirty cap/snap to MDSs, > and the unmounting won't wait the possible acks, which will ihode > the inodes when updating the metadata locally but makes no sense > any more, of this. This will make the evict_inodes() to skip these > inodes. > > If encrypt is enabled the kernel generate a warning when removing > the encrypt keys when the skipped inodes still hold the keyring: > > WARNING: CPU: 4 PID: 168846 at fs/crypto/keyring.c:242 fscrypt_destroy_keyring+0x7e/0xd0 > CPU: 4 PID: 168846 Comm: umount Tainted: G S 6.1.0-rc5-ceph-g72ead199864c #1 > Hardware name: Supermicro SYS-5018R-WR/X10SRW-F, BIOS 2.0 12/17/2015 > RIP: 0010:fscrypt_destroy_keyring+0x7e/0xd0 > RSP: 0018:ffffc9000b277e28 EFLAGS: 00010202 > RAX: 0000000000000002 RBX: ffff88810d52ac00 RCX: ffff88810b56aa00 > RDX: 0000000080000000 RSI: ffffffff822f3a09 RDI: ffff888108f59000 > RBP: ffff8881d394fb88 R08: 0000000000000028 R09: 0000000000000000 > R10: 0000000000000001 R11: 11ff4fe6834fcd91 R12: ffff8881d394fc40 > R13: ffff888108f59000 R14: ffff8881d394f800 R15: 0000000000000000 > FS: 00007fd83f6f1080(0000) GS:ffff88885fd00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f918d417000 CR3: 000000017f89a005 CR4: 00000000003706e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > generic_shutdown_super+0x47/0x120 > kill_anon_super+0x14/0x30 > ceph_kill_sb+0x36/0x90 [ceph] > deactivate_locked_super+0x29/0x60 > cleanup_mnt+0xb8/0x140 > task_work_run+0x67/0xb0 > exit_to_user_mode_prepare+0x23d/0x240 > syscall_exit_to_user_mode+0x25/0x60 > do_syscall_64+0x40/0x80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7fd83dc39e9b > > Later the kernel will crash when iput() the inodes and dereferencing > the "sb->s_master_keys", which has been released by the > generic_shutdown_super(). > > URL: https://tracker.ceph.com/issues/58126 > URL: https://tracker.ceph.com/issues/59162 > Signed-off-by: Xiubo Li <xiubli@redhat.com> > --- > > Only updated the 2/2 patch since series V3: > > Changed in V4: > - Always resend the session close requests to MDS when receives > new messages just before dropping them. > - Even receives a corrupted message we should increase the s_seq > and resend the session close requests. > > > fs/ceph/caps.c | 6 ++++- > fs/ceph/mds_client.c | 14 ++++++++--- > fs/ceph/mds_client.h | 11 ++++++++- > fs/ceph/quota.c | 9 ++++--- > fs/ceph/snap.c | 10 ++++---- > fs/ceph/super.c | 57 ++++++++++++++++++++++++++++++++++++++++++++ > fs/ceph/super.h | 3 +++ > 7 files changed, 96 insertions(+), 14 deletions(-) > > diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c > index 6379c0070492..e1bb6d9c16f8 100644 > --- a/fs/ceph/caps.c > +++ b/fs/ceph/caps.c > @@ -4222,6 +4222,9 @@ void ceph_handle_caps(struct ceph_mds_session *session, > > dout("handle_caps from mds%d\n", session->s_mds); > > + if (!ceph_inc_stopping_blocker(mdsc, session)) > + return; > + > /* decode */ > end = msg->front.iov_base + msg->front.iov_len; > if (msg->front.iov_len < sizeof(*h)) > @@ -4323,7 +4326,6 @@ void ceph_handle_caps(struct ceph_mds_session *session, > vino.snap, inode); > > mutex_lock(&session->s_mutex); > - inc_session_sequence(session); > dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq, > (unsigned)seq); > > @@ -4435,6 +4437,8 @@ void ceph_handle_caps(struct ceph_mds_session *session, > done_unlocked: > iput(inode); > out: > + ceph_dec_stopping_blocker(mdsc); > + > ceph_put_string(extra_info.pool_ns); > > /* Defer closing the sessions after s_mutex lock being released */ > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c > index 85d639f75ea1..21ca41e5f68b 100644 > --- a/fs/ceph/mds_client.c > +++ b/fs/ceph/mds_client.c > @@ -4877,6 +4877,9 @@ static void handle_lease(struct ceph_mds_client *mdsc, > > dout("handle_lease from mds%d\n", mds); > > + if (!ceph_inc_stopping_blocker(mdsc, session)) > + return; > + > /* decode */ > if (msg->front.iov_len < sizeof(*h) + sizeof(u32)) > goto bad; > @@ -4895,8 +4898,6 @@ static void handle_lease(struct ceph_mds_client *mdsc, > dname.len, dname.name); > > mutex_lock(&session->s_mutex); > - inc_session_sequence(session); > - > if (!inode) { > dout("handle_lease no inode %llx\n", vino.ino); > goto release; > @@ -4958,9 +4959,13 @@ static void handle_lease(struct ceph_mds_client *mdsc, > out: > mutex_unlock(&session->s_mutex); > iput(inode); > + > + ceph_dec_stopping_blocker(mdsc); > return; > > bad: > + ceph_dec_stopping_blocker(mdsc); > + > pr_err("corrupt lease message\n"); > ceph_msg_dump(msg); > } > @@ -5156,6 +5161,9 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc) > } > > init_completion(&mdsc->safe_umount_waiters); > + spin_lock_init(&mdsc->stopping_lock); > + atomic_set(&mdsc->stopping_blockers, 0); > + init_completion(&mdsc->stopping_waiter); > init_waitqueue_head(&mdsc->session_close_wq); > INIT_LIST_HEAD(&mdsc->waiting_for_map); > mdsc->quotarealms_inodes = RB_ROOT; > @@ -5270,7 +5278,7 @@ void send_flush_mdlog(struct ceph_mds_session *s) > void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc) > { > dout("pre_umount\n"); > - mdsc->stopping = 1; > + mdsc->stopping = CEPH_MDSC_STOPPING_BEGAIN; > > ceph_mdsc_iterate_sessions(mdsc, send_flush_mdlog, true); > ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false); > diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h > index 81a1f9a4ac3b..5bf32701c84c 100644 > --- a/fs/ceph/mds_client.h > +++ b/fs/ceph/mds_client.h > @@ -398,6 +398,11 @@ struct cap_wait { > int want; > }; > > +enum { > + CEPH_MDSC_STOPPING_BEGAIN = 1, Typo: I think you want to define this as "CEPH_MDSC_STOPPING_BEGIN" instead, right? > + CEPH_MDSC_STOPPING_FLUSHED = 2, > +}; > + > /* > * mds client state > */ > @@ -414,7 +419,11 @@ struct ceph_mds_client { > struct ceph_mds_session **sessions; /* NULL for mds if no session */ > atomic_t num_sessions; > int max_sessions; /* len of sessions array */ > - int stopping; /* true if shutting down */ > + > + spinlock_t stopping_lock; /* protect snap_empty */ > + int stopping; /* the stage of shutting down */ > + atomic_t stopping_blockers; > + struct completion stopping_waiter; > > atomic64_t quotarealms_count; /* # realms with quota */ > /* > diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c > index 64592adfe48f..37b062783717 100644 > --- a/fs/ceph/quota.c > +++ b/fs/ceph/quota.c > @@ -47,6 +47,9 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, > struct inode *inode; > struct ceph_inode_info *ci; > > + if (!ceph_inc_stopping_blocker(mdsc, session)) > + return; > + > if (msg->front.iov_len < sizeof(*h)) { > pr_err("%s corrupt message mds%d len %d\n", __func__, > session->s_mds, (int)msg->front.iov_len); > @@ -54,11 +57,6 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, > return; > } > > - /* increment msg sequence number */ > - mutex_lock(&session->s_mutex); > - inc_session_sequence(session); > - mutex_unlock(&session->s_mutex); > - > /* lookup inode */ > vino.ino = le64_to_cpu(h->ino); > vino.snap = CEPH_NOSNAP; > @@ -78,6 +76,7 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, > spin_unlock(&ci->i_ceph_lock); > > iput(inode); > + ceph_dec_stopping_blocker(mdsc); There are two 'return' statements in this function where function ceph_dec_stopping_blocker() isn't being called. > } > > static struct ceph_quotarealm_inode * > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c > index aa8e0657fc03..23b31600ee3c 100644 > --- a/fs/ceph/snap.c > +++ b/fs/ceph/snap.c > @@ -1011,6 +1011,9 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, > int locked_rwsem = 0; > bool close_sessions = false; > > + if (!ceph_inc_stopping_blocker(mdsc, session)) > + return; > + > /* decode */ > if (msg->front.iov_len < sizeof(*h)) > goto bad; > @@ -1026,10 +1029,6 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, > dout("%s from mds%d op %s split %llx tracelen %d\n", __func__, > mds, ceph_snap_op_name(op), split, trace_len); > > - mutex_lock(&session->s_mutex); > - inc_session_sequence(session); > - mutex_unlock(&session->s_mutex); > - > down_write(&mdsc->snap_rwsem); > locked_rwsem = 1; > > @@ -1134,12 +1133,15 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, > up_write(&mdsc->snap_rwsem); > > flush_snaps(mdsc); > + ceph_dec_stopping_blocker(mdsc); > return; > > bad: > pr_err("%s corrupt snap message from mds%d\n", __func__, mds); > ceph_msg_dump(msg); > out: > + ceph_dec_stopping_blocker(mdsc); > + > if (locked_rwsem) > up_write(&mdsc->snap_rwsem); > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c > index 4b0a070d5c6d..f5ddd4abc0ab 100644 > --- a/fs/ceph/super.c > +++ b/fs/ceph/super.c > @@ -1467,15 +1467,72 @@ static int ceph_init_fs_context(struct fs_context *fc) > return -ENOMEM; > } > > +/* > + * Return true if mdsc successfully increase blocker counter, > + * or false if the mdsc is in stopping and flushed state. > + */ > +bool ceph_inc_stopping_blocker(struct ceph_mds_client *mdsc, > + struct ceph_mds_session *session) > +{ > + mutex_lock(&session->s_mutex); > + inc_session_sequence(session); > + mutex_unlock(&session->s_mutex); > + > + spin_lock(&mdsc->stopping_lock); > + if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) { > + spin_unlock(&mdsc->stopping_lock); > + return false; > + } > + atomic_inc(&mdsc->stopping_blockers); > + spin_unlock(&mdsc->stopping_lock); > + return true; > +} > + > +void ceph_dec_stopping_blocker(struct ceph_mds_client *mdsc) > +{ > + spin_lock(&mdsc->stopping_lock); > + if (!atomic_dec_return(&mdsc->stopping_blockers) && > + mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) > + complete_all(&mdsc->stopping_waiter); > + spin_unlock(&mdsc->stopping_lock); > +} > + > static void ceph_kill_sb(struct super_block *s) > { > struct ceph_fs_client *fsc = ceph_sb_to_client(s); > + bool wait; > > dout("kill_sb %p\n", s); > > ceph_mdsc_pre_umount(fsc->mdsc); > flush_fs_workqueues(fsc); > > + /* > + * Though the kill_anon_super() will finally trigger the > + * sync_filesystem() anyway, we still need to do it here and > + * then bump the stage of shutdown. This will allow us to > + * drop any further message, which will increase the inodes' > + * i_count reference counters but makes no sense any more, > + * from MDSs. > + * > + * Without this when evicting the inodes it may fail in the > + * kill_anon_super(), which will trigger a warning when > + * destroying the fscrypt keyring and then possibly trigger > + * a further crash in ceph module when the iput() tries to > + * evict the inodes later. > + */ > + sync_filesystem(s); > + > + spin_lock(&fsc->mdsc->stopping_lock); > + fsc->mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHED; > + wait = !!atomic_read(&fsc->mdsc->stopping_blockers); > + spin_unlock(&fsc->mdsc->stopping_lock); > + > + while (wait || atomic_read(&fsc->mdsc->stopping_blockers)) { > + wait = false; > + wait_for_completion(&fsc->mdsc->stopping_waiter); > + } This is a odd construct :-) I'd rather see it like this: if (wait) { while (atomic_read(&fsc->mdsc->stopping_blockers)) wait_for_completion(&fsc->mdsc->stopping_waiter); } But... even with my suggestion, can't we deadlock here if we get preempted just before the wait_for_completion() and ceph_dec_stopping_blocker() is executed? Cheers,
On 29/03/2023 22:41, Luís Henriques wrote: > Hi! > > I finally got to have a look at this patch because I found that the > version you sent along with fscrypt v17 is a bit different from what's in > the testing branch :-) Yeah, after v17 I updated this and force pushed to the testing branch to run the test. > xiubli@redhat.com writes: > >> From: Xiubo Li <xiubli@redhat.com> >> >> When unmounting and all the dirty buffer will be flushed and after >> the last osd request is finished the last reference of the i_count >> will be released. Then it will flush the dirty cap/snap to MDSs, >> and the unmounting won't wait the possible acks, which will ihode >> the inodes when updating the metadata locally but makes no sense >> any more, of this. This will make the evict_inodes() to skip these >> inodes. >> >> If encrypt is enabled the kernel generate a warning when removing >> the encrypt keys when the skipped inodes still hold the keyring: >> >> WARNING: CPU: 4 PID: 168846 at fs/crypto/keyring.c:242 fscrypt_destroy_keyring+0x7e/0xd0 >> CPU: 4 PID: 168846 Comm: umount Tainted: G S 6.1.0-rc5-ceph-g72ead199864c #1 >> Hardware name: Supermicro SYS-5018R-WR/X10SRW-F, BIOS 2.0 12/17/2015 >> RIP: 0010:fscrypt_destroy_keyring+0x7e/0xd0 >> RSP: 0018:ffffc9000b277e28 EFLAGS: 00010202 >> RAX: 0000000000000002 RBX: ffff88810d52ac00 RCX: ffff88810b56aa00 >> RDX: 0000000080000000 RSI: ffffffff822f3a09 RDI: ffff888108f59000 >> RBP: ffff8881d394fb88 R08: 0000000000000028 R09: 0000000000000000 >> R10: 0000000000000001 R11: 11ff4fe6834fcd91 R12: ffff8881d394fc40 >> R13: ffff888108f59000 R14: ffff8881d394f800 R15: 0000000000000000 >> FS: 00007fd83f6f1080(0000) GS:ffff88885fd00000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 00007f918d417000 CR3: 000000017f89a005 CR4: 00000000003706e0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> Call Trace: >> <TASK> >> generic_shutdown_super+0x47/0x120 >> kill_anon_super+0x14/0x30 >> ceph_kill_sb+0x36/0x90 [ceph] >> deactivate_locked_super+0x29/0x60 >> cleanup_mnt+0xb8/0x140 >> task_work_run+0x67/0xb0 >> exit_to_user_mode_prepare+0x23d/0x240 >> syscall_exit_to_user_mode+0x25/0x60 >> do_syscall_64+0x40/0x80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> RIP: 0033:0x7fd83dc39e9b >> >> Later the kernel will crash when iput() the inodes and dereferencing >> the "sb->s_master_keys", which has been released by the >> generic_shutdown_super(). >> >> URL: https://tracker.ceph.com/issues/58126 >> URL: https://tracker.ceph.com/issues/59162 >> Signed-off-by: Xiubo Li <xiubli@redhat.com> >> --- >> >> Only updated the 2/2 patch since series V3: >> >> Changed in V4: >> - Always resend the session close requests to MDS when receives >> new messages just before dropping them. >> - Even receives a corrupted message we should increase the s_seq >> and resend the session close requests. >> >> >> fs/ceph/caps.c | 6 ++++- >> fs/ceph/mds_client.c | 14 ++++++++--- >> fs/ceph/mds_client.h | 11 ++++++++- >> fs/ceph/quota.c | 9 ++++--- >> fs/ceph/snap.c | 10 ++++---- >> fs/ceph/super.c | 57 ++++++++++++++++++++++++++++++++++++++++++++ >> fs/ceph/super.h | 3 +++ >> 7 files changed, 96 insertions(+), 14 deletions(-) >> >> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c >> index 6379c0070492..e1bb6d9c16f8 100644 >> --- a/fs/ceph/caps.c >> +++ b/fs/ceph/caps.c >> @@ -4222,6 +4222,9 @@ void ceph_handle_caps(struct ceph_mds_session *session, >> >> dout("handle_caps from mds%d\n", session->s_mds); >> >> + if (!ceph_inc_stopping_blocker(mdsc, session)) >> + return; >> + >> /* decode */ >> end = msg->front.iov_base + msg->front.iov_len; >> if (msg->front.iov_len < sizeof(*h)) >> @@ -4323,7 +4326,6 @@ void ceph_handle_caps(struct ceph_mds_session *session, >> vino.snap, inode); >> >> mutex_lock(&session->s_mutex); >> - inc_session_sequence(session); >> dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq, >> (unsigned)seq); >> >> @@ -4435,6 +4437,8 @@ void ceph_handle_caps(struct ceph_mds_session *session, >> done_unlocked: >> iput(inode); >> out: >> + ceph_dec_stopping_blocker(mdsc); >> + >> ceph_put_string(extra_info.pool_ns); >> >> /* Defer closing the sessions after s_mutex lock being released */ >> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c >> index 85d639f75ea1..21ca41e5f68b 100644 >> --- a/fs/ceph/mds_client.c >> +++ b/fs/ceph/mds_client.c >> @@ -4877,6 +4877,9 @@ static void handle_lease(struct ceph_mds_client *mdsc, >> >> dout("handle_lease from mds%d\n", mds); >> >> + if (!ceph_inc_stopping_blocker(mdsc, session)) >> + return; >> + >> /* decode */ >> if (msg->front.iov_len < sizeof(*h) + sizeof(u32)) >> goto bad; >> @@ -4895,8 +4898,6 @@ static void handle_lease(struct ceph_mds_client *mdsc, >> dname.len, dname.name); >> >> mutex_lock(&session->s_mutex); >> - inc_session_sequence(session); >> - >> if (!inode) { >> dout("handle_lease no inode %llx\n", vino.ino); >> goto release; >> @@ -4958,9 +4959,13 @@ static void handle_lease(struct ceph_mds_client *mdsc, >> out: >> mutex_unlock(&session->s_mutex); >> iput(inode); >> + >> + ceph_dec_stopping_blocker(mdsc); >> return; >> >> bad: >> + ceph_dec_stopping_blocker(mdsc); >> + >> pr_err("corrupt lease message\n"); >> ceph_msg_dump(msg); >> } >> @@ -5156,6 +5161,9 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc) >> } >> >> init_completion(&mdsc->safe_umount_waiters); >> + spin_lock_init(&mdsc->stopping_lock); >> + atomic_set(&mdsc->stopping_blockers, 0); >> + init_completion(&mdsc->stopping_waiter); >> init_waitqueue_head(&mdsc->session_close_wq); >> INIT_LIST_HEAD(&mdsc->waiting_for_map); >> mdsc->quotarealms_inodes = RB_ROOT; >> @@ -5270,7 +5278,7 @@ void send_flush_mdlog(struct ceph_mds_session *s) >> void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc) >> { >> dout("pre_umount\n"); >> - mdsc->stopping = 1; >> + mdsc->stopping = CEPH_MDSC_STOPPING_BEGAIN; >> >> ceph_mdsc_iterate_sessions(mdsc, send_flush_mdlog, true); >> ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false); >> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h >> index 81a1f9a4ac3b..5bf32701c84c 100644 >> --- a/fs/ceph/mds_client.h >> +++ b/fs/ceph/mds_client.h >> @@ -398,6 +398,11 @@ struct cap_wait { >> int want; >> }; >> >> +enum { >> + CEPH_MDSC_STOPPING_BEGAIN = 1, > Typo: I think you want to define this as "CEPH_MDSC_STOPPING_BEGIN" > instead, right? Yeah, good catch. >> + CEPH_MDSC_STOPPING_FLUSHED = 2, >> +}; >> + >> /* >> * mds client state >> */ >> @@ -414,7 +419,11 @@ struct ceph_mds_client { >> struct ceph_mds_session **sessions; /* NULL for mds if no session */ >> atomic_t num_sessions; >> int max_sessions; /* len of sessions array */ >> - int stopping; /* true if shutting down */ >> + >> + spinlock_t stopping_lock; /* protect snap_empty */ >> + int stopping; /* the stage of shutting down */ >> + atomic_t stopping_blockers; >> + struct completion stopping_waiter; >> >> atomic64_t quotarealms_count; /* # realms with quota */ >> /* >> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c >> index 64592adfe48f..37b062783717 100644 >> --- a/fs/ceph/quota.c >> +++ b/fs/ceph/quota.c >> @@ -47,6 +47,9 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, >> struct inode *inode; >> struct ceph_inode_info *ci; >> >> + if (!ceph_inc_stopping_blocker(mdsc, session)) >> + return; >> + >> if (msg->front.iov_len < sizeof(*h)) { >> pr_err("%s corrupt message mds%d len %d\n", __func__, >> session->s_mds, (int)msg->front.iov_len); >> @@ -54,11 +57,6 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, >> return; >> } >> >> - /* increment msg sequence number */ >> - mutex_lock(&session->s_mutex); >> - inc_session_sequence(session); >> - mutex_unlock(&session->s_mutex); >> - >> /* lookup inode */ >> vino.ino = le64_to_cpu(h->ino); >> vino.snap = CEPH_NOSNAP; >> @@ -78,6 +76,7 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, >> spin_unlock(&ci->i_ceph_lock); >> >> iput(inode); >> + ceph_dec_stopping_blocker(mdsc); > There are two 'return' statements in this function where function > ceph_dec_stopping_blocker() isn't being called. Good catch. >> } >> >> static struct ceph_quotarealm_inode * >> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c >> index aa8e0657fc03..23b31600ee3c 100644 >> --- a/fs/ceph/snap.c >> +++ b/fs/ceph/snap.c >> @@ -1011,6 +1011,9 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, >> int locked_rwsem = 0; >> bool close_sessions = false; >> >> + if (!ceph_inc_stopping_blocker(mdsc, session)) >> + return; >> + >> /* decode */ >> if (msg->front.iov_len < sizeof(*h)) >> goto bad; >> @@ -1026,10 +1029,6 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, >> dout("%s from mds%d op %s split %llx tracelen %d\n", __func__, >> mds, ceph_snap_op_name(op), split, trace_len); >> >> - mutex_lock(&session->s_mutex); >> - inc_session_sequence(session); >> - mutex_unlock(&session->s_mutex); >> - >> down_write(&mdsc->snap_rwsem); >> locked_rwsem = 1; >> >> @@ -1134,12 +1133,15 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, >> up_write(&mdsc->snap_rwsem); >> >> flush_snaps(mdsc); >> + ceph_dec_stopping_blocker(mdsc); >> return; >> >> bad: >> pr_err("%s corrupt snap message from mds%d\n", __func__, mds); >> ceph_msg_dump(msg); >> out: >> + ceph_dec_stopping_blocker(mdsc); >> + >> if (locked_rwsem) >> up_write(&mdsc->snap_rwsem); >> >> diff --git a/fs/ceph/super.c b/fs/ceph/super.c >> index 4b0a070d5c6d..f5ddd4abc0ab 100644 >> --- a/fs/ceph/super.c >> +++ b/fs/ceph/super.c >> @@ -1467,15 +1467,72 @@ static int ceph_init_fs_context(struct fs_context *fc) >> return -ENOMEM; >> } >> >> +/* >> + * Return true if mdsc successfully increase blocker counter, >> + * or false if the mdsc is in stopping and flushed state. >> + */ >> +bool ceph_inc_stopping_blocker(struct ceph_mds_client *mdsc, >> + struct ceph_mds_session *session) >> +{ >> + mutex_lock(&session->s_mutex); >> + inc_session_sequence(session); >> + mutex_unlock(&session->s_mutex); >> + >> + spin_lock(&mdsc->stopping_lock); >> + if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) { >> + spin_unlock(&mdsc->stopping_lock); >> + return false; >> + } >> + atomic_inc(&mdsc->stopping_blockers); >> + spin_unlock(&mdsc->stopping_lock); >> + return true; >> +} >> + >> +void ceph_dec_stopping_blocker(struct ceph_mds_client *mdsc) >> +{ >> + spin_lock(&mdsc->stopping_lock); >> + if (!atomic_dec_return(&mdsc->stopping_blockers) && >> + mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) >> + complete_all(&mdsc->stopping_waiter); >> + spin_unlock(&mdsc->stopping_lock); >> +} >> + >> static void ceph_kill_sb(struct super_block *s) >> { >> struct ceph_fs_client *fsc = ceph_sb_to_client(s); >> + bool wait; >> >> dout("kill_sb %p\n", s); >> >> ceph_mdsc_pre_umount(fsc->mdsc); >> flush_fs_workqueues(fsc); >> >> + /* >> + * Though the kill_anon_super() will finally trigger the >> + * sync_filesystem() anyway, we still need to do it here and >> + * then bump the stage of shutdown. This will allow us to >> + * drop any further message, which will increase the inodes' >> + * i_count reference counters but makes no sense any more, >> + * from MDSs. >> + * >> + * Without this when evicting the inodes it may fail in the >> + * kill_anon_super(), which will trigger a warning when >> + * destroying the fscrypt keyring and then possibly trigger >> + * a further crash in ceph module when the iput() tries to >> + * evict the inodes later. >> + */ >> + sync_filesystem(s); >> + >> + spin_lock(&fsc->mdsc->stopping_lock); >> + fsc->mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHED; >> + wait = !!atomic_read(&fsc->mdsc->stopping_blockers); >> + spin_unlock(&fsc->mdsc->stopping_lock); >> + >> + while (wait || atomic_read(&fsc->mdsc->stopping_blockers)) { >> + wait = false; >> + wait_for_completion(&fsc->mdsc->stopping_waiter); >> + } > This is a odd construct :-) I'd rather see it like this: > > if (wait) { > while (atomic_read(&fsc->mdsc->stopping_blockers)) > wait_for_completion(&fsc->mdsc->stopping_waiter); > } This also looks good to me. As I remembered when reading the kernel code I just saw another place in VFS is also doing like this and I just followed it. > But... even with my suggestion, can't we deadlock here if we get preempted > just before the wait_for_completion() and ceph_dec_stopping_blocker() is > executed? Good question. Actually it won't. The 'x->done' member in the completion will be initialized as 0, and the complete_all() will set it to 'UINT_MAX'. And only when 'x->done == 0' will the wait_for_completion() go to sleep and wait. Thanks - Xiubo > > Cheers,
Xiubo Li <xiubli@redhat.com> writes: > On 29/03/2023 22:41, Luís Henriques wrote: <...> > This also looks good to me. As I remembered when reading the kernel code I just > saw another place in VFS is also doing like this and I just followed it. >> But... even with my suggestion, can't we deadlock here if we get preempted >> just before the wait_for_completion() and ceph_dec_stopping_blocker() is >> executed? > > Good question. Actually it won't. Yeah, you're right. Doh! > The 'x->done' member in the completion will be initialized as 0, and the > complete_all() will set it to 'UINT_MAX'. And only when 'x->done == 0' will the > wait_for_completion() go to sleep and wait. Cheers,
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 6379c0070492..e1bb6d9c16f8 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -4222,6 +4222,9 @@ void ceph_handle_caps(struct ceph_mds_session *session, dout("handle_caps from mds%d\n", session->s_mds); + if (!ceph_inc_stopping_blocker(mdsc, session)) + return; + /* decode */ end = msg->front.iov_base + msg->front.iov_len; if (msg->front.iov_len < sizeof(*h)) @@ -4323,7 +4326,6 @@ void ceph_handle_caps(struct ceph_mds_session *session, vino.snap, inode); mutex_lock(&session->s_mutex); - inc_session_sequence(session); dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq, (unsigned)seq); @@ -4435,6 +4437,8 @@ void ceph_handle_caps(struct ceph_mds_session *session, done_unlocked: iput(inode); out: + ceph_dec_stopping_blocker(mdsc); + ceph_put_string(extra_info.pool_ns); /* Defer closing the sessions after s_mutex lock being released */ diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 85d639f75ea1..21ca41e5f68b 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4877,6 +4877,9 @@ static void handle_lease(struct ceph_mds_client *mdsc, dout("handle_lease from mds%d\n", mds); + if (!ceph_inc_stopping_blocker(mdsc, session)) + return; + /* decode */ if (msg->front.iov_len < sizeof(*h) + sizeof(u32)) goto bad; @@ -4895,8 +4898,6 @@ static void handle_lease(struct ceph_mds_client *mdsc, dname.len, dname.name); mutex_lock(&session->s_mutex); - inc_session_sequence(session); - if (!inode) { dout("handle_lease no inode %llx\n", vino.ino); goto release; @@ -4958,9 +4959,13 @@ static void handle_lease(struct ceph_mds_client *mdsc, out: mutex_unlock(&session->s_mutex); iput(inode); + + ceph_dec_stopping_blocker(mdsc); return; bad: + ceph_dec_stopping_blocker(mdsc); + pr_err("corrupt lease message\n"); ceph_msg_dump(msg); } @@ -5156,6 +5161,9 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc) } init_completion(&mdsc->safe_umount_waiters); + spin_lock_init(&mdsc->stopping_lock); + atomic_set(&mdsc->stopping_blockers, 0); + init_completion(&mdsc->stopping_waiter); init_waitqueue_head(&mdsc->session_close_wq); INIT_LIST_HEAD(&mdsc->waiting_for_map); mdsc->quotarealms_inodes = RB_ROOT; @@ -5270,7 +5278,7 @@ void send_flush_mdlog(struct ceph_mds_session *s) void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc) { dout("pre_umount\n"); - mdsc->stopping = 1; + mdsc->stopping = CEPH_MDSC_STOPPING_BEGAIN; ceph_mdsc_iterate_sessions(mdsc, send_flush_mdlog, true); ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false); diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index 81a1f9a4ac3b..5bf32701c84c 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -398,6 +398,11 @@ struct cap_wait { int want; }; +enum { + CEPH_MDSC_STOPPING_BEGAIN = 1, + CEPH_MDSC_STOPPING_FLUSHED = 2, +}; + /* * mds client state */ @@ -414,7 +419,11 @@ struct ceph_mds_client { struct ceph_mds_session **sessions; /* NULL for mds if no session */ atomic_t num_sessions; int max_sessions; /* len of sessions array */ - int stopping; /* true if shutting down */ + + spinlock_t stopping_lock; /* protect snap_empty */ + int stopping; /* the stage of shutting down */ + atomic_t stopping_blockers; + struct completion stopping_waiter; atomic64_t quotarealms_count; /* # realms with quota */ /* diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c index 64592adfe48f..37b062783717 100644 --- a/fs/ceph/quota.c +++ b/fs/ceph/quota.c @@ -47,6 +47,9 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, struct inode *inode; struct ceph_inode_info *ci; + if (!ceph_inc_stopping_blocker(mdsc, session)) + return; + if (msg->front.iov_len < sizeof(*h)) { pr_err("%s corrupt message mds%d len %d\n", __func__, session->s_mds, (int)msg->front.iov_len); @@ -54,11 +57,6 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, return; } - /* increment msg sequence number */ - mutex_lock(&session->s_mutex); - inc_session_sequence(session); - mutex_unlock(&session->s_mutex); - /* lookup inode */ vino.ino = le64_to_cpu(h->ino); vino.snap = CEPH_NOSNAP; @@ -78,6 +76,7 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, spin_unlock(&ci->i_ceph_lock); iput(inode); + ceph_dec_stopping_blocker(mdsc); } static struct ceph_quotarealm_inode * diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index aa8e0657fc03..23b31600ee3c 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -1011,6 +1011,9 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, int locked_rwsem = 0; bool close_sessions = false; + if (!ceph_inc_stopping_blocker(mdsc, session)) + return; + /* decode */ if (msg->front.iov_len < sizeof(*h)) goto bad; @@ -1026,10 +1029,6 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, dout("%s from mds%d op %s split %llx tracelen %d\n", __func__, mds, ceph_snap_op_name(op), split, trace_len); - mutex_lock(&session->s_mutex); - inc_session_sequence(session); - mutex_unlock(&session->s_mutex); - down_write(&mdsc->snap_rwsem); locked_rwsem = 1; @@ -1134,12 +1133,15 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, up_write(&mdsc->snap_rwsem); flush_snaps(mdsc); + ceph_dec_stopping_blocker(mdsc); return; bad: pr_err("%s corrupt snap message from mds%d\n", __func__, mds); ceph_msg_dump(msg); out: + ceph_dec_stopping_blocker(mdsc); + if (locked_rwsem) up_write(&mdsc->snap_rwsem); diff --git a/fs/ceph/super.c b/fs/ceph/super.c index 4b0a070d5c6d..f5ddd4abc0ab 100644 --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -1467,15 +1467,72 @@ static int ceph_init_fs_context(struct fs_context *fc) return -ENOMEM; } +/* + * Return true if mdsc successfully increase blocker counter, + * or false if the mdsc is in stopping and flushed state. + */ +bool ceph_inc_stopping_blocker(struct ceph_mds_client *mdsc, + struct ceph_mds_session *session) +{ + mutex_lock(&session->s_mutex); + inc_session_sequence(session); + mutex_unlock(&session->s_mutex); + + spin_lock(&mdsc->stopping_lock); + if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) { + spin_unlock(&mdsc->stopping_lock); + return false; + } + atomic_inc(&mdsc->stopping_blockers); + spin_unlock(&mdsc->stopping_lock); + return true; +} + +void ceph_dec_stopping_blocker(struct ceph_mds_client *mdsc) +{ + spin_lock(&mdsc->stopping_lock); + if (!atomic_dec_return(&mdsc->stopping_blockers) && + mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED) + complete_all(&mdsc->stopping_waiter); + spin_unlock(&mdsc->stopping_lock); +} + static void ceph_kill_sb(struct super_block *s) { struct ceph_fs_client *fsc = ceph_sb_to_client(s); + bool wait; dout("kill_sb %p\n", s); ceph_mdsc_pre_umount(fsc->mdsc); flush_fs_workqueues(fsc); + /* + * Though the kill_anon_super() will finally trigger the + * sync_filesystem() anyway, we still need to do it here and + * then bump the stage of shutdown. This will allow us to + * drop any further message, which will increase the inodes' + * i_count reference counters but makes no sense any more, + * from MDSs. + * + * Without this when evicting the inodes it may fail in the + * kill_anon_super(), which will trigger a warning when + * destroying the fscrypt keyring and then possibly trigger + * a further crash in ceph module when the iput() tries to + * evict the inodes later. + */ + sync_filesystem(s); + + spin_lock(&fsc->mdsc->stopping_lock); + fsc->mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHED; + wait = !!atomic_read(&fsc->mdsc->stopping_blockers); + spin_unlock(&fsc->mdsc->stopping_lock); + + while (wait || atomic_read(&fsc->mdsc->stopping_blockers)) { + wait = false; + wait_for_completion(&fsc->mdsc->stopping_waiter); + } + kill_anon_super(s); fsc->client->extra_mon_dispatch = NULL; diff --git a/fs/ceph/super.h b/fs/ceph/super.h index a785e5cb9b40..8a9afa81a76f 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -1398,4 +1398,7 @@ extern bool ceph_quota_update_statfs(struct ceph_fs_client *fsc, struct kstatfs *buf); extern void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc); +bool ceph_inc_stopping_blocker(struct ceph_mds_client *mdsc, + struct ceph_mds_session *session); +void ceph_dec_stopping_blocker(struct ceph_mds_client *mdsc); #endif /* _FS_CEPH_SUPER_H */