| Message ID | 20241119004928.3245873-7-neilb@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | nfsd: allocate/free session-based DRC slots on demand | expand |
On Tue, Nov 19, 2024 at 11:41:33AM +1100, NeilBrown wrote: > Add a shrinker which frees unused slots and may ask the clients to use > fewer slots on each session. > > Each session now tracks se_client_maxreqs which is the most recent > max-requests-in-use reported by the client, and se_target_maxreqs which > is a target number of requests which is reduced by the shrinker. > > The shrinker iterates over all sessions on all client in all > net-namespaces and reduces the target by 1 for each. The shrinker may > get called multiple times to reduce by more than 1 each. > > If se_target_maxreqs is above se_client_maxreqs, those slots can be > freed immediately. If not the client will be ask to reduce its usage > and as the usage goes down slots will be freed. > > Once the usage has dropped to match the target, the target can be > increased if the client uses all available slots and if a GFP_NOWAIT > allocation succeeds. > > Signed-off-by: NeilBrown <neilb@suse.de> > --- > fs/nfsd/nfs4state.c | 72 ++++++++++++++++++++++++++++++++++++++++++--- > fs/nfsd/state.h | 1 + > 2 files changed, 69 insertions(+), 4 deletions(-) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 0625b0aec6b8..ac49c3bd0dcb 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -1909,6 +1909,16 @@ gen_sessionid(struct nfsd4_session *ses) > */ > #define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44) > > +static struct shrinker *nfsd_slot_shrinker; > +static DEFINE_SPINLOCK(nfsd_session_list_lock); > +static LIST_HEAD(nfsd_session_list); > +/* The sum of "target_slots-1" on every session. The shrinker can push this > + * down, though it can take a little while for the memory to actually > + * be freed. The "-1" is because we can never free slot 0 while the > + * session is active. > + */ > +static atomic_t nfsd_total_target_slots = ATOMIC_INIT(0); > + > static void > free_session_slots(struct nfsd4_session *ses, int from) > { > @@ -1931,11 +1941,14 @@ free_session_slots(struct nfsd4_session *ses, int from) > kfree(slot); > } > ses->se_fchannel.maxreqs = from; > - if (ses->se_target_maxslots > from) > - ses->se_target_maxslots = from; > + if (ses->se_target_maxslots > from) { > + int new_target = from ?: 1; > + atomic_sub(ses->se_target_maxslots - new_target, &nfsd_total_target_slots); > + ses->se_target_maxslots = new_target; > + } > } > > -static int __maybe_unused > +static int > reduce_session_slots(struct nfsd4_session *ses, int dec) > { > struct nfsd_net *nn = net_generic(ses->se_client->net, > @@ -1948,6 +1961,7 @@ reduce_session_slots(struct nfsd4_session *ses, int dec) > return ret; > ret = min(dec, ses->se_target_maxslots-1); > ses->se_target_maxslots -= ret; > + atomic_sub(ret, &nfsd_total_target_slots); > ses->se_slot_gen += 1; > if (ses->se_slot_gen == 0) { > int i; > @@ -2006,6 +2020,7 @@ static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs, > fattrs->maxreqs = i; > memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs)); > new->se_target_maxslots = i; > + atomic_add(i - 1, &nfsd_total_target_slots); > new->se_cb_slot_avail = ~0U; > new->se_cb_highest_slot = min(battrs->maxreqs - 1, > NFSD_BC_SLOT_TABLE_SIZE - 1); > @@ -2130,6 +2145,36 @@ static void free_session(struct nfsd4_session *ses) > __free_session(ses); > } > > +static unsigned long > +nfsd_slot_count(struct shrinker *s, struct shrink_control *sc) > +{ > + unsigned long cnt = atomic_read(&nfsd_total_target_slots); > + > + return cnt ? cnt : SHRINK_EMPTY; > +} > + > +static unsigned long > +nfsd_slot_scan(struct shrinker *s, struct shrink_control *sc) > +{ > + struct nfsd4_session *ses; > + unsigned long scanned = 0; > + unsigned long freed = 0; > + > + spin_lock(&nfsd_session_list_lock); > + list_for_each_entry(ses, &nfsd_session_list, se_all_sessions) { > + freed += reduce_session_slots(ses, 1); > + scanned += 1; > + if (scanned >= sc->nr_to_scan) { > + /* Move starting point for next scan */ > + list_move(&nfsd_session_list, &ses->se_all_sessions); > + break; > + } > + } > + spin_unlock(&nfsd_session_list_lock); > + sc->nr_scanned = scanned; > + return freed; > +} > + > static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses) > { > int idx; > @@ -2154,6 +2199,10 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru > list_add(&new->se_perclnt, &clp->cl_sessions); > spin_unlock(&clp->cl_lock); > > + spin_lock(&nfsd_session_list_lock); > + list_add_tail(&new->se_all_sessions, &nfsd_session_list); > + spin_unlock(&nfsd_session_list_lock); > + > { > struct sockaddr *sa = svc_addr(rqstp); > /* > @@ -2223,6 +2272,9 @@ unhash_session(struct nfsd4_session *ses) > spin_lock(&ses->se_client->cl_lock); > list_del(&ses->se_perclnt); > spin_unlock(&ses->se_client->cl_lock); > + spin_lock(&nfsd_session_list_lock); > + list_del(&ses->se_all_sessions); > + spin_unlock(&nfsd_session_list_lock); > } > > /* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */ > @@ -4335,6 +4387,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, > slot->sl_seqid = seq->seqid; > slot->sl_flags &= ~NFSD4_SLOT_REUSED; > slot->sl_flags |= NFSD4_SLOT_INUSE; > + slot->sl_generation = session->se_slot_gen; > if (seq->cachethis) > slot->sl_flags |= NFSD4_SLOT_CACHETHIS; > else > @@ -4371,6 +4424,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, > if (slot && !xa_is_err(xa_store(&session->se_slots, s, slot, > GFP_ATOMIC))) { > session->se_fchannel.maxreqs += 1; > + atomic_add(session->se_fchannel.maxreqs - session->se_target_maxslots, > + &nfsd_total_target_slots); > session->se_target_maxslots = session->se_fchannel.maxreqs; > } else { > kfree(slot); > @@ -8779,7 +8834,6 @@ nfs4_state_start_net(struct net *net) > } > > /* initialization to perform when the nfsd service is started: */ > - > int > nfs4_state_start(void) > { > @@ -8789,6 +8843,15 @@ nfs4_state_start(void) > if (ret) > return ret; > > + nfsd_slot_shrinker = shrinker_alloc(0, "nfsd-DRC-slot"); > + if (!nfsd_slot_shrinker) { > + rhltable_destroy(&nfs4_file_rhltable); > + return -ENOMEM; > + } > + nfsd_slot_shrinker->count_objects = nfsd_slot_count; > + nfsd_slot_shrinker->scan_objects = nfsd_slot_scan; > + shrinker_register(nfsd_slot_shrinker); > + > set_max_delegations(); > return 0; > } > @@ -8830,6 +8893,7 @@ void > nfs4_state_shutdown(void) > { > rhltable_destroy(&nfs4_file_rhltable); > + shrinker_free(nfsd_slot_shrinker); > } > > static void > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > index ea6659d52be2..0e320ba097f2 100644 > --- a/fs/nfsd/state.h > +++ b/fs/nfsd/state.h > @@ -345,6 +345,7 @@ struct nfsd4_session { > bool se_dead; > struct list_head se_hash; /* hash by sessionid */ > struct list_head se_perclnt; > + struct list_head se_all_sessions;/* global list of sessions */ I think my only minor issue here is whether we truly want an "all_sessions" list. Since we don't expect the shrinker to run very often, isn't there another mechanism that can already iterate all clients and their sessions? > struct nfs4_client *se_client; > struct nfs4_sessionid se_sessionid; > struct nfsd4_channel_attrs se_fchannel; > -- > 2.47.0 >
On Tue, 2024-11-19 at 11:41 +1100, NeilBrown wrote: > Add a shrinker which frees unused slots and may ask the clients to use > fewer slots on each session. > > Each session now tracks se_client_maxreqs which is the most recent > max-requests-in-use reported by the client, and se_target_maxreqs which > is a target number of requests which is reduced by the shrinker. > > The shrinker iterates over all sessions on all client in all > net-namespaces and reduces the target by 1 for each. The shrinker may > get called multiple times to reduce by more than 1 each. > > If se_target_maxreqs is above se_client_maxreqs, those slots can be > freed immediately. If not the client will be ask to reduce its usage > and as the usage goes down slots will be freed. > > Once the usage has dropped to match the target, the target can be > increased if the client uses all available slots and if a GFP_NOWAIT > allocation succeeds. > > Signed-off-by: NeilBrown <neilb@suse.de> > --- > fs/nfsd/nfs4state.c | 72 ++++++++++++++++++++++++++++++++++++++++++--- > fs/nfsd/state.h | 1 + > 2 files changed, 69 insertions(+), 4 deletions(-) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 0625b0aec6b8..ac49c3bd0dcb 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -1909,6 +1909,16 @@ gen_sessionid(struct nfsd4_session *ses) > */ > #define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44) > > +static struct shrinker *nfsd_slot_shrinker; > +static DEFINE_SPINLOCK(nfsd_session_list_lock); > +static LIST_HEAD(nfsd_session_list); > +/* The sum of "target_slots-1" on every session. The shrinker can push this > + * down, though it can take a little while for the memory to actually > + * be freed. The "-1" is because we can never free slot 0 while the > + * session is active. > + */ > +static atomic_t nfsd_total_target_slots = ATOMIC_INIT(0); > + > static void > free_session_slots(struct nfsd4_session *ses, int from) > { > @@ -1931,11 +1941,14 @@ free_session_slots(struct nfsd4_session *ses, int from) > kfree(slot); > } > ses->se_fchannel.maxreqs = from; > - if (ses->se_target_maxslots > from) > - ses->se_target_maxslots = from; > + if (ses->se_target_maxslots > from) { > + int new_target = from ?: 1; Let's make that "from ? from : 1". The above is a non-standard gcc-ism (AIUI). > + atomic_sub(ses->se_target_maxslots - new_target, &nfsd_total_target_slots); > + ses->se_target_maxslots = new_target; > + } > } > > -static int __maybe_unused > +static int > reduce_session_slots(struct nfsd4_session *ses, int dec) > { > struct nfsd_net *nn = net_generic(ses->se_client->net, > @@ -1948,6 +1961,7 @@ reduce_session_slots(struct nfsd4_session *ses, int dec) > return ret; > ret = min(dec, ses->se_target_maxslots-1); > ses->se_target_maxslots -= ret; > + atomic_sub(ret, &nfsd_total_target_slots); > ses->se_slot_gen += 1; > if (ses->se_slot_gen == 0) { > int i; > @@ -2006,6 +2020,7 @@ static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs, > fattrs->maxreqs = i; > memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs)); > new->se_target_maxslots = i; > + atomic_add(i - 1, &nfsd_total_target_slots); > new->se_cb_slot_avail = ~0U; > new->se_cb_highest_slot = min(battrs->maxreqs - 1, > NFSD_BC_SLOT_TABLE_SIZE - 1); > @@ -2130,6 +2145,36 @@ static void free_session(struct nfsd4_session *ses) > __free_session(ses); > } > > +static unsigned long > +nfsd_slot_count(struct shrinker *s, struct shrink_control *sc) > +{ > + unsigned long cnt = atomic_read(&nfsd_total_target_slots); > + > + return cnt ? cnt : SHRINK_EMPTY; > +} > + > +static unsigned long > +nfsd_slot_scan(struct shrinker *s, struct shrink_control *sc) > +{ > + struct nfsd4_session *ses; > + unsigned long scanned = 0; > + unsigned long freed = 0; > + > + spin_lock(&nfsd_session_list_lock); > + list_for_each_entry(ses, &nfsd_session_list, se_all_sessions) { > + freed += reduce_session_slots(ses, 1); > + scanned += 1; > + if (scanned >= sc->nr_to_scan) { > + /* Move starting point for next scan */ > + list_move(&nfsd_session_list, &ses->se_all_sessions); > + break; > + } > + } > + spin_unlock(&nfsd_session_list_lock); > + sc->nr_scanned = scanned; > + return freed; > +} > + > static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses) > { > int idx; > @@ -2154,6 +2199,10 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru > list_add(&new->se_perclnt, &clp->cl_sessions); > spin_unlock(&clp->cl_lock); > > + spin_lock(&nfsd_session_list_lock); > + list_add_tail(&new->se_all_sessions, &nfsd_session_list); > + spin_unlock(&nfsd_session_list_lock); > + > { > struct sockaddr *sa = svc_addr(rqstp); > /* > @@ -2223,6 +2272,9 @@ unhash_session(struct nfsd4_session *ses) > spin_lock(&ses->se_client->cl_lock); > list_del(&ses->se_perclnt); > spin_unlock(&ses->se_client->cl_lock); > + spin_lock(&nfsd_session_list_lock); > + list_del(&ses->se_all_sessions); > + spin_unlock(&nfsd_session_list_lock); > } > > /* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */ > @@ -4335,6 +4387,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, > slot->sl_seqid = seq->seqid; > slot->sl_flags &= ~NFSD4_SLOT_REUSED; > slot->sl_flags |= NFSD4_SLOT_INUSE; > + slot->sl_generation = session->se_slot_gen; > if (seq->cachethis) > slot->sl_flags |= NFSD4_SLOT_CACHETHIS; > else > @@ -4371,6 +4424,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, > if (slot && !xa_is_err(xa_store(&session->se_slots, s, slot, > GFP_ATOMIC))) { > session->se_fchannel.maxreqs += 1; > + atomic_add(session->se_fchannel.maxreqs - session->se_target_maxslots, > + &nfsd_total_target_slots); > session->se_target_maxslots = session->se_fchannel.maxreqs; > } else { > kfree(slot); > @@ -8779,7 +8834,6 @@ nfs4_state_start_net(struct net *net) > } > > /* initialization to perform when the nfsd service is started: */ > - > int > nfs4_state_start(void) > { > @@ -8789,6 +8843,15 @@ nfs4_state_start(void) > if (ret) > return ret; > > + nfsd_slot_shrinker = shrinker_alloc(0, "nfsd-DRC-slot"); > + if (!nfsd_slot_shrinker) { > + rhltable_destroy(&nfs4_file_rhltable); > + return -ENOMEM; > + } > + nfsd_slot_shrinker->count_objects = nfsd_slot_count; > + nfsd_slot_shrinker->scan_objects = nfsd_slot_scan; > + shrinker_register(nfsd_slot_shrinker); > + > set_max_delegations(); > return 0; > } > @@ -8830,6 +8893,7 @@ void > nfs4_state_shutdown(void) > { > rhltable_destroy(&nfs4_file_rhltable); > + shrinker_free(nfsd_slot_shrinker); > } > > static void > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > index ea6659d52be2..0e320ba097f2 100644 > --- a/fs/nfsd/state.h > +++ b/fs/nfsd/state.h > @@ -345,6 +345,7 @@ struct nfsd4_session { > bool se_dead; > struct list_head se_hash; /* hash by sessionid */ > struct list_head se_perclnt; > + struct list_head se_all_sessions;/* global list of sessions */ > struct nfs4_client *se_client; > struct nfs4_sessionid se_sessionid; > struct nfsd4_channel_attrs se_fchannel;
On Wed, 20 Nov 2024, Chuck Lever wrote: > On Tue, Nov 19, 2024 at 11:41:33AM +1100, NeilBrown wrote: > > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > > index ea6659d52be2..0e320ba097f2 100644 > > --- a/fs/nfsd/state.h > > +++ b/fs/nfsd/state.h > > @@ -345,6 +345,7 @@ struct nfsd4_session { > > bool se_dead; > > struct list_head se_hash; /* hash by sessionid */ > > struct list_head se_perclnt; > > + struct list_head se_all_sessions;/* global list of sessions */ > > I think my only minor issue here is whether we truly want an > "all_sessions" list. Since we don't expect the shrinker to run very > often, isn't there another mechanism that can already iterate all > clients and their sessions? "all_sessions" certainly isn't my favourite part of the set. But I do think we need it. We can iterate all sessions by iterating all net-namespaces, then all clients, then all sessions. But that isn't what we need. The shrinker mechanism seems to assume an LRU. It makes "scan" requests one "batch" at a time, and may request several batches in sequence without telling you in advance how many batches to expect. So you need some concept of the "next" thing to free. Often this is the end of the LRU. But we don't have an LRU because the slots aren't a cache. An important detail is that when nfsd_slot_scan() has scanned all that it was asked, it moves the head to the current point in the list. So the next time it is called it will start with the correct next session. This will only become important where there are more than 64 (default batch size) sessions. NeilBrown > > > > struct nfs4_client *se_client; > > struct nfs4_sessionid se_sessionid; > > struct nfsd4_channel_attrs se_fchannel; > > -- > > 2.47.0 > > > > -- > Chuck Lever >
On Wed, 20 Nov 2024, Jeff Layton wrote: > On Tue, 2024-11-19 at 11:41 +1100, NeilBrown wrote: > > Add a shrinker which frees unused slots and may ask the clients to use > > fewer slots on each session. > > > > Each session now tracks se_client_maxreqs which is the most recent > > max-requests-in-use reported by the client, and se_target_maxreqs which > > is a target number of requests which is reduced by the shrinker. > > > > The shrinker iterates over all sessions on all client in all > > net-namespaces and reduces the target by 1 for each. The shrinker may > > get called multiple times to reduce by more than 1 each. > > > > If se_target_maxreqs is above se_client_maxreqs, those slots can be > > freed immediately. If not the client will be ask to reduce its usage > > and as the usage goes down slots will be freed. > > > > Once the usage has dropped to match the target, the target can be > > increased if the client uses all available slots and if a GFP_NOWAIT > > allocation succeeds. > > > > Signed-off-by: NeilBrown <neilb@suse.de> > > --- > > fs/nfsd/nfs4state.c | 72 ++++++++++++++++++++++++++++++++++++++++++--- > > fs/nfsd/state.h | 1 + > > 2 files changed, 69 insertions(+), 4 deletions(-) > > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > index 0625b0aec6b8..ac49c3bd0dcb 100644 > > --- a/fs/nfsd/nfs4state.c > > +++ b/fs/nfsd/nfs4state.c > > @@ -1909,6 +1909,16 @@ gen_sessionid(struct nfsd4_session *ses) > > */ > > #define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44) > > > > +static struct shrinker *nfsd_slot_shrinker; > > +static DEFINE_SPINLOCK(nfsd_session_list_lock); > > +static LIST_HEAD(nfsd_session_list); > > +/* The sum of "target_slots-1" on every session. The shrinker can push this > > + * down, though it can take a little while for the memory to actually > > + * be freed. The "-1" is because we can never free slot 0 while the > > + * session is active. > > + */ > > +static atomic_t nfsd_total_target_slots = ATOMIC_INIT(0); > > + > > static void > > free_session_slots(struct nfsd4_session *ses, int from) > > { > > @@ -1931,11 +1941,14 @@ free_session_slots(struct nfsd4_session *ses, int from) > > kfree(slot); > > } > > ses->se_fchannel.maxreqs = from; > > - if (ses->se_target_maxslots > from) > > - ses->se_target_maxslots = from; > > + if (ses->se_target_maxslots > from) { > > + int new_target = from ?: 1; > > Let's make that "from ? from : 1". The above is a non-standard gcc-ism > (AIUI). Let's not. There are currently 1926 lines in .c and .h files in the Linux kernel which contain "?:" and another 848 which contain "? :". I think it is an established part of the kernel style. This is admittedly dominated by bcachefs, but there is a long tail with tools, net, crypto, drivers all contributing. Outside of bcachefs, fs/ contributes only 102 in 29 different filesystems. Thanks, NeilBrown
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 0625b0aec6b8..ac49c3bd0dcb 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1909,6 +1909,16 @@ gen_sessionid(struct nfsd4_session *ses) */ #define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44) +static struct shrinker *nfsd_slot_shrinker; +static DEFINE_SPINLOCK(nfsd_session_list_lock); +static LIST_HEAD(nfsd_session_list); +/* The sum of "target_slots-1" on every session. The shrinker can push this + * down, though it can take a little while for the memory to actually + * be freed. The "-1" is because we can never free slot 0 while the + * session is active. + */ +static atomic_t nfsd_total_target_slots = ATOMIC_INIT(0); + static void free_session_slots(struct nfsd4_session *ses, int from) { @@ -1931,11 +1941,14 @@ free_session_slots(struct nfsd4_session *ses, int from) kfree(slot); } ses->se_fchannel.maxreqs = from; - if (ses->se_target_maxslots > from) - ses->se_target_maxslots = from; + if (ses->se_target_maxslots > from) { + int new_target = from ?: 1; + atomic_sub(ses->se_target_maxslots - new_target, &nfsd_total_target_slots); + ses->se_target_maxslots = new_target; + } } -static int __maybe_unused +static int reduce_session_slots(struct nfsd4_session *ses, int dec) { struct nfsd_net *nn = net_generic(ses->se_client->net, @@ -1948,6 +1961,7 @@ reduce_session_slots(struct nfsd4_session *ses, int dec) return ret; ret = min(dec, ses->se_target_maxslots-1); ses->se_target_maxslots -= ret; + atomic_sub(ret, &nfsd_total_target_slots); ses->se_slot_gen += 1; if (ses->se_slot_gen == 0) { int i; @@ -2006,6 +2020,7 @@ static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs, fattrs->maxreqs = i; memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs)); new->se_target_maxslots = i; + atomic_add(i - 1, &nfsd_total_target_slots); new->se_cb_slot_avail = ~0U; new->se_cb_highest_slot = min(battrs->maxreqs - 1, NFSD_BC_SLOT_TABLE_SIZE - 1); @@ -2130,6 +2145,36 @@ static void free_session(struct nfsd4_session *ses) __free_session(ses); } +static unsigned long +nfsd_slot_count(struct shrinker *s, struct shrink_control *sc) +{ + unsigned long cnt = atomic_read(&nfsd_total_target_slots); + + return cnt ? cnt : SHRINK_EMPTY; +} + +static unsigned long +nfsd_slot_scan(struct shrinker *s, struct shrink_control *sc) +{ + struct nfsd4_session *ses; + unsigned long scanned = 0; + unsigned long freed = 0; + + spin_lock(&nfsd_session_list_lock); + list_for_each_entry(ses, &nfsd_session_list, se_all_sessions) { + freed += reduce_session_slots(ses, 1); + scanned += 1; + if (scanned >= sc->nr_to_scan) { + /* Move starting point for next scan */ + list_move(&nfsd_session_list, &ses->se_all_sessions); + break; + } + } + spin_unlock(&nfsd_session_list_lock); + sc->nr_scanned = scanned; + return freed; +} + static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses) { int idx; @@ -2154,6 +2199,10 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru list_add(&new->se_perclnt, &clp->cl_sessions); spin_unlock(&clp->cl_lock); + spin_lock(&nfsd_session_list_lock); + list_add_tail(&new->se_all_sessions, &nfsd_session_list); + spin_unlock(&nfsd_session_list_lock); + { struct sockaddr *sa = svc_addr(rqstp); /* @@ -2223,6 +2272,9 @@ unhash_session(struct nfsd4_session *ses) spin_lock(&ses->se_client->cl_lock); list_del(&ses->se_perclnt); spin_unlock(&ses->se_client->cl_lock); + spin_lock(&nfsd_session_list_lock); + list_del(&ses->se_all_sessions); + spin_unlock(&nfsd_session_list_lock); } /* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */ @@ -4335,6 +4387,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, slot->sl_seqid = seq->seqid; slot->sl_flags &= ~NFSD4_SLOT_REUSED; slot->sl_flags |= NFSD4_SLOT_INUSE; + slot->sl_generation = session->se_slot_gen; if (seq->cachethis) slot->sl_flags |= NFSD4_SLOT_CACHETHIS; else @@ -4371,6 +4424,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, if (slot && !xa_is_err(xa_store(&session->se_slots, s, slot, GFP_ATOMIC))) { session->se_fchannel.maxreqs += 1; + atomic_add(session->se_fchannel.maxreqs - session->se_target_maxslots, + &nfsd_total_target_slots); session->se_target_maxslots = session->se_fchannel.maxreqs; } else { kfree(slot); @@ -8779,7 +8834,6 @@ nfs4_state_start_net(struct net *net) } /* initialization to perform when the nfsd service is started: */ - int nfs4_state_start(void) { @@ -8789,6 +8843,15 @@ nfs4_state_start(void) if (ret) return ret; + nfsd_slot_shrinker = shrinker_alloc(0, "nfsd-DRC-slot"); + if (!nfsd_slot_shrinker) { + rhltable_destroy(&nfs4_file_rhltable); + return -ENOMEM; + } + nfsd_slot_shrinker->count_objects = nfsd_slot_count; + nfsd_slot_shrinker->scan_objects = nfsd_slot_scan; + shrinker_register(nfsd_slot_shrinker); + set_max_delegations(); return 0; } @@ -8830,6 +8893,7 @@ void nfs4_state_shutdown(void) { rhltable_destroy(&nfs4_file_rhltable); + shrinker_free(nfsd_slot_shrinker); } static void diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index ea6659d52be2..0e320ba097f2 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -345,6 +345,7 @@ struct nfsd4_session { bool se_dead; struct list_head se_hash; /* hash by sessionid */ struct list_head se_perclnt; + struct list_head se_all_sessions;/* global list of sessions */ struct nfs4_client *se_client; struct nfs4_sessionid se_sessionid; struct nfsd4_channel_attrs se_fchannel;
Add a shrinker which frees unused slots and may ask the clients to use fewer slots on each session. Each session now tracks se_client_maxreqs which is the most recent max-requests-in-use reported by the client, and se_target_maxreqs which is a target number of requests which is reduced by the shrinker. The shrinker iterates over all sessions on all client in all net-namespaces and reduces the target by 1 for each. The shrinker may get called multiple times to reduce by more than 1 each. If se_target_maxreqs is above se_client_maxreqs, those slots can be freed immediately. If not the client will be ask to reduce its usage and as the usage goes down slots will be freed. Once the usage has dropped to match the target, the target can be increased if the client uses all available slots and if a GFP_NOWAIT allocation succeeds. Signed-off-by: NeilBrown <neilb@suse.de> --- fs/nfsd/nfs4state.c | 72 ++++++++++++++++++++++++++++++++++++++++++--- fs/nfsd/state.h | 1 + 2 files changed, 69 insertions(+), 4 deletions(-)