From: Philipp Reisner Date: Thu, 5 May 2011 14:13:10 +0000 (+0200) Subject: drbd: Removing drbd_cfg_rwsem X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=c141ebda031a0550d75634f7c94f7c85c2d5c9f5;p=deliverable%2Flinux.git drbd: Removing drbd_cfg_rwsem * Updates to all configuration items is done under genl_lock(). Including removal of mdevs or tconns. * All read non sleeping read sides are protected by rcu * All sleeping read sides keep reference counts to keep the objects alive Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index 8bc604e72d18..56b190c65546 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -169,11 +169,8 @@ drbd_insert_fault(struct drbd_conf *mdev, unsigned int type) { #define DRBD_MD_MAGIC (DRBD_MAGIC+4) extern struct ratelimit_state drbd_ratelimit_state; -extern struct idr minors; -extern struct list_head drbd_tconns; -extern struct rw_semaphore drbd_cfg_rwsem; -/* drbd_cfg_rwsem protects: drbd_tconns list, minors idr, tconn->volumes idr - note: non sleeping iterations over the idrs are protoected by RCU */ +extern struct idr minors; /* RCU, updates: genl_lock() */ +extern struct list_head drbd_tconns; /* RCU, updates: genl_lock() */ /* on the wire */ enum drbd_packet { @@ -1477,7 +1474,7 @@ extern struct page *drbd_alloc_pages(struct drbd_conf *, unsigned int, bool); extern void drbd_set_recv_tcq(struct drbd_conf *mdev, int tcq_enabled); extern void _drbd_clear_done_ee(struct drbd_conf *mdev, struct list_head *to_be_freed); extern void conn_flush_workqueue(struct drbd_tconn *tconn); -extern int drbd_connected(int vnr, void *p, void *data); +extern int drbd_connected(struct drbd_conf *mdev); static inline void drbd_flush_workqueue(struct drbd_conf *mdev) { conn_flush_workqueue(mdev->tconn); diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 771b53ece970..22c2b4c881da 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -120,7 +120,6 @@ module_param_string(usermode_helper, usermode_helper, sizeof(usermode_helper), 0 */ struct idr minors; struct list_head drbd_tconns; /* list of struct drbd_tconn */ -DECLARE_RWSEM(drbd_cfg_rwsem); struct kmem_cache *drbd_request_cache; struct kmem_cache *drbd_ee_cache; /* peer requests */ @@ -2331,21 +2330,20 @@ static void drbd_cleanup(void) drbd_genl_unregister(); - down_write(&drbd_cfg_rwsem); idr_for_each_entry(&minors, mdev, i) { idr_remove(&minors, mdev_to_minor(mdev)); idr_remove(&mdev->tconn->volumes, mdev->vnr); del_gendisk(mdev->vdisk); - synchronize_rcu(); + /* synchronize_rcu(); No other threads running at this point */ kref_put(&mdev->kref, &drbd_minor_destroy); } + /* not _rcu since, no other updater anymore. Genl already unregistered */ list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) { - list_del_rcu(&tconn->all_tconn); - synchronize_rcu(); + list_del(&tconn->all_tconn); /* not _rcu no proc, not other threads */ + /* synchronize_rcu(); */ kref_put(&tconn->kref, &conn_destroy); } - up_write(&drbd_cfg_rwsem); drbd_destroy_mempools(); unregister_blkdev(DRBD_MAJOR, "drbd"); @@ -2408,7 +2406,7 @@ struct drbd_tconn *conn_get_by_name(const char *name) if (!name || !name[0]) return NULL; - down_read(&drbd_cfg_rwsem); + rcu_read_lock(); list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) { if (!strcmp(tconn->name, name)) { kref_get(&tconn->kref); @@ -2417,7 +2415,7 @@ struct drbd_tconn *conn_get_by_name(const char *name) } tconn = NULL; found: - up_read(&drbd_cfg_rwsem); + rcu_read_unlock(); return tconn; } @@ -2502,10 +2500,8 @@ struct drbd_tconn *conn_create(const char *name) drbd_set_res_opts_defaults(&tconn->res_opts); - down_write(&drbd_cfg_rwsem); kref_init(&tconn->kref); list_add_tail_rcu(&tconn->all_tconn, &drbd_tconns); - up_write(&drbd_cfg_rwsem); return tconn; @@ -2637,7 +2633,7 @@ enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, /* inherit the connection state */ mdev->state.conn = tconn->cstate; if (mdev->state.conn == C_WF_REPORT_PARAMS) - drbd_connected(vnr, mdev, tconn); + drbd_connected(mdev); return NO_ERROR; @@ -2913,12 +2909,10 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev) } spin_unlock_irq(&mdev->tconn->req_lock); - mutex_lock(&mdev->tconn->conf_update); /* This blocks wants to be get removed... */ bdev->disk_conf->al_extents = be32_to_cpu(buffer->al_nr_extents); if (bdev->disk_conf->al_extents < DRBD_AL_EXTENTS_MIN) bdev->disk_conf->al_extents = DRBD_AL_EXTENTS_DEF; - mutex_unlock(&mdev->tconn->conf_update); err: mutex_unlock(&mdev->md_io_mutex); diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index a0cf0005baf9..72ce3b0d0e03 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -335,10 +335,15 @@ static void conn_md_sync(struct drbd_tconn *tconn) struct drbd_conf *mdev; int vnr; - down_read(&drbd_cfg_rwsem); - idr_for_each_entry(&tconn->volumes, mdev, vnr) + rcu_read_lock(); + idr_for_each_entry(&tconn->volumes, mdev, vnr) { + kref_get(&mdev->kref); + rcu_read_unlock(); drbd_md_sync(mdev); - up_read(&drbd_cfg_rwsem); + kref_put(&mdev->kref, &drbd_minor_destroy); + rcu_read_lock(); + } + rcu_read_unlock(); } int conn_khelper(struct drbd_tconn *tconn, char *cmd) @@ -1193,12 +1198,12 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info) rcu_assign_pointer(mdev->rs_plan_s, new_plan); } + mutex_unlock(&mdev->tconn->conf_update); drbd_md_sync(mdev); if (mdev->state.conn >= C_CONNECTED) drbd_send_sync_param(mdev); - mutex_unlock(&mdev->tconn->conf_update); synchronize_rcu(); kfree(old_disk_conf); kfree(old_plan); @@ -2013,7 +2018,7 @@ int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info) new_my_addr = (struct sockaddr *)&new_conf->my_addr; new_peer_addr = (struct sockaddr *)&new_conf->peer_addr; - /* No need to take drbd_cfg_rwsem here. All reconfiguration is + /* No need for _rcu here. All reconfiguration is * strictly serialized on genl_lock(). We are protected against * concurrent reconfiguration/addition/deletion */ list_for_each_entry(oconn, &drbd_tconns, all_tconn) { @@ -2672,7 +2677,7 @@ int get_one_status(struct sk_buff *skb, struct netlink_callback *cb) */ /* synchronize with conn_create()/conn_destroy() */ - down_read(&drbd_cfg_rwsem); + rcu_read_lock(); /* revalidate iterator position */ list_for_each_entry_rcu(tmp, &drbd_tconns, all_tconn) { if (pos == NULL) { @@ -2738,7 +2743,7 @@ next_tconn: } out: - up_read(&drbd_cfg_rwsem); + rcu_read_unlock(); /* where to start the next iteration */ cb->args[0] = (long)pos; cb->args[1] = (pos == tconn) ? volume + 1 : 0; @@ -3018,9 +3023,7 @@ int drbd_adm_add_minor(struct sk_buff *skb, struct genl_info *info) goto out; } - down_write(&drbd_cfg_rwsem); retcode = conn_new_minor(adm_ctx.tconn, dh->minor, adm_ctx.volume); - up_write(&drbd_cfg_rwsem); out: drbd_adm_finish(info, retcode); return 0; @@ -3053,9 +3056,7 @@ int drbd_adm_delete_minor(struct sk_buff *skb, struct genl_info *info) if (retcode != NO_ERROR) goto out; - down_write(&drbd_cfg_rwsem); retcode = adm_delete_minor(adm_ctx.mdev); - up_write(&drbd_cfg_rwsem); out: drbd_adm_finish(info, retcode); return 0; @@ -3078,52 +3079,43 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info) goto out; } - down_read(&drbd_cfg_rwsem); /* demote */ idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) { retcode = drbd_set_role(mdev, R_SECONDARY, 0); if (retcode < SS_SUCCESS) { drbd_msg_put_info("failed to demote"); - goto out_unlock; + goto out; } } - up_read(&drbd_cfg_rwsem); - /* disconnect; may stop the receiver; - * must not hold the drbd_cfg_rwsem */ retcode = conn_try_disconnect(adm_ctx.tconn, 0); if (retcode < SS_SUCCESS) { drbd_msg_put_info("failed to disconnect"); goto out; } - down_read(&drbd_cfg_rwsem); /* detach */ idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) { retcode = adm_detach(mdev); if (retcode < SS_SUCCESS) { drbd_msg_put_info("failed to detach"); - goto out_unlock; + goto out; } } - up_read(&drbd_cfg_rwsem); /* If we reach this, all volumes (of this tconn) are Secondary, * Disconnected, Diskless, aka Unconfigured. Make sure all threads have - * actually stopped, state handling only does drbd_thread_stop_nowait(). - * This needs to be done without holding drbd_cfg_rwsem. */ + * actually stopped, state handling only does drbd_thread_stop_nowait(). */ drbd_thread_stop(&adm_ctx.tconn->worker); /* Now, nothing can fail anymore */ /* delete volumes */ - down_write(&drbd_cfg_rwsem); idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) { retcode = adm_delete_minor(mdev); if (retcode != NO_ERROR) { /* "can not happen" */ drbd_msg_put_info("failed to delete volume"); - up_write(&drbd_cfg_rwsem); goto out; } } @@ -3140,10 +3132,7 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info) retcode = ERR_CONN_IN_USE; drbd_msg_put_info("failed to delete connection"); } - up_write(&drbd_cfg_rwsem); goto out; -out_unlock: - up_read(&drbd_cfg_rwsem); out: drbd_adm_finish(info, retcode); return 0; @@ -3159,7 +3148,6 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info) if (retcode != NO_ERROR) goto out; - down_write(&drbd_cfg_rwsem); if (conn_lowest_minor(adm_ctx.tconn) < 0) { list_del_rcu(&adm_ctx.tconn->all_tconn); synchronize_rcu(); @@ -3169,7 +3157,6 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info) } else { retcode = ERR_CONN_IN_USE; } - up_write(&drbd_cfg_rwsem); if (retcode == NO_ERROR) drbd_thread_stop(&adm_ctx.tconn->worker); diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c index 792a71ec2e69..6b226cca1e83 100644 --- a/drivers/block/drbd/drbd_proc.c +++ b/drivers/block/drbd/drbd_proc.c @@ -229,7 +229,7 @@ static int drbd_seq_show(struct seq_file *seq, void *v) oos .. known out-of-sync kB */ - down_read(&drbd_cfg_rwsem); + rcu_read_lock(); idr_for_each_entry(&minors, mdev, i) { if (prev_i != i - 1) seq_printf(seq, "\n"); @@ -242,10 +242,8 @@ static int drbd_seq_show(struct seq_file *seq, void *v) mdev->state.role == R_SECONDARY) { seq_printf(seq, "%2d: cs:Unconfigured\n", i); } else { - rcu_read_lock(); nc = rcu_dereference(mdev->tconn->net_conf); wp = nc ? nc->wire_protocol - DRBD_PROT_A + 'A' : ' '; - rcu_read_unlock(); seq_printf(seq, "%2d: cs:%s ro:%s/%s ds:%s/%s %c %c%c%c%c%c%c\n" " ns:%u nr:%u dw:%u dr:%u al:%u bm:%u " @@ -299,7 +297,7 @@ static int drbd_seq_show(struct seq_file *seq, void *v) } } } - up_read(&drbd_cfg_rwsem); + rcu_read_unlock(); return 0; } diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index 7156e53b0000..aa42967398e3 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -63,7 +63,7 @@ enum finish_epoch { static int drbd_do_features(struct drbd_tconn *tconn); static int drbd_do_auth(struct drbd_tconn *tconn); -static int drbd_disconnected(int vnr, void *p, void *data); +static int drbd_disconnected(struct drbd_conf *mdev); static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *, struct drbd_epoch *, enum epoch_event); static int e_end_block(struct drbd_work *, int); @@ -811,9 +811,8 @@ static int drbd_socket_okay(struct socket **sock) } /* Gets called if a connection is established, or if a new minor gets created in a connection */ -int drbd_connected(int vnr, void *p, void *data) +int drbd_connected(struct drbd_conf *mdev) { - struct drbd_conf *mdev = (struct drbd_conf *)p; int err; atomic_set(&mdev->packet_seq, 0); @@ -847,8 +846,9 @@ int drbd_connected(int vnr, void *p, void *data) static int conn_connect(struct drbd_tconn *tconn) { struct socket *sock, *msock; + struct drbd_conf *mdev; struct net_conf *nc; - int timeout, try, h, ok; + int vnr, timeout, try, h, ok; if (conn_request_state(tconn, NS(conn, C_WF_CONNECTION), CS_VERBOSE) < SS_SUCCESS) return -2; @@ -1001,9 +1001,16 @@ retry: if (drbd_send_protocol(tconn) == -EOPNOTSUPP) return -1; - down_read(&drbd_cfg_rwsem); - h = !idr_for_each(&tconn->volumes, drbd_connected, tconn); - up_read(&drbd_cfg_rwsem); + rcu_read_lock(); + idr_for_each_entry(&tconn->volumes, mdev, vnr) { + kref_get(&mdev->kref); + rcu_read_unlock(); + drbd_connected(mdev); + kref_put(&mdev->kref, &drbd_minor_destroy); + rcu_read_lock(); + } + rcu_read_unlock(); + return h; out_release_sockets: @@ -4242,8 +4249,9 @@ void conn_flush_workqueue(struct drbd_tconn *tconn) static void conn_disconnect(struct drbd_tconn *tconn) { + struct drbd_conf *mdev; enum drbd_conns oc; - int rv = SS_UNKNOWN_ERROR; + int vnr, rv = SS_UNKNOWN_ERROR; if (tconn->cstate == C_STANDALONE) return; @@ -4252,9 +4260,16 @@ static void conn_disconnect(struct drbd_tconn *tconn) drbd_thread_stop(&tconn->asender); drbd_free_sock(tconn); - down_read(&drbd_cfg_rwsem); - idr_for_each(&tconn->volumes, drbd_disconnected, tconn); - up_read(&drbd_cfg_rwsem); + rcu_read_lock(); + idr_for_each_entry(&tconn->volumes, mdev, vnr) { + kref_get(&mdev->kref); + rcu_read_unlock(); + drbd_disconnected(mdev); + kref_put(&mdev->kref, &drbd_minor_destroy); + rcu_read_lock(); + } + rcu_read_unlock(); + conn_info(tconn, "Connection closed\n"); if (conn_highest_role(tconn) == R_PRIMARY && conn_highest_pdsk(tconn) >= D_UNKNOWN) @@ -4271,9 +4286,8 @@ static void conn_disconnect(struct drbd_tconn *tconn) conn_request_state(tconn, NS(conn, C_STANDALONE), CS_VERBOSE | CS_HARD); } -static int drbd_disconnected(int vnr, void *p, void *data) +static int drbd_disconnected(struct drbd_conf *mdev) { - struct drbd_conf *mdev = (struct drbd_conf *)p; enum drbd_fencing_p fp; unsigned int i; @@ -4974,30 +4988,33 @@ static int got_skip(struct drbd_tconn *tconn, struct packet_info *pi) static int tconn_finish_peer_reqs(struct drbd_tconn *tconn) { struct drbd_conf *mdev; - int i, not_empty = 0; + int vnr, not_empty = 0; do { clear_bit(SIGNAL_ASENDER, &tconn->flags); flush_signals(current); - down_read(&drbd_cfg_rwsem); - idr_for_each_entry(&tconn->volumes, mdev, i) { + + rcu_read_lock(); + idr_for_each_entry(&tconn->volumes, mdev, vnr) { + kref_get(&mdev->kref); + rcu_read_unlock(); if (drbd_finish_peer_reqs(mdev)) { - up_read(&drbd_cfg_rwsem); - return 1; /* error */ + kref_put(&mdev->kref, &drbd_minor_destroy); + return 1; } + kref_put(&mdev->kref, &drbd_minor_destroy); + rcu_read_lock(); } - up_read(&drbd_cfg_rwsem); set_bit(SIGNAL_ASENDER, &tconn->flags); spin_lock_irq(&tconn->req_lock); - rcu_read_lock(); - idr_for_each_entry(&tconn->volumes, mdev, i) { + idr_for_each_entry(&tconn->volumes, mdev, vnr) { not_empty = !list_empty(&mdev->done_ee); if (not_empty) break; } - rcu_read_unlock(); spin_unlock_irq(&tconn->req_lock); + rcu_read_unlock(); } while (not_empty); return 0; diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c index 78c3de49eff6..ec8f4245ef9a 100644 --- a/drivers/block/drbd/drbd_worker.c +++ b/drivers/block/drbd/drbd_worker.c @@ -1774,12 +1774,16 @@ int drbd_worker(struct drbd_thread *thi) */ spin_unlock_irq(&tconn->data.work.q_lock); - down_read(&drbd_cfg_rwsem); + rcu_read_lock(); idr_for_each_entry(&tconn->volumes, mdev, vnr) { D_ASSERT(mdev->state.disk == D_DISKLESS && mdev->state.conn == C_STANDALONE); + kref_get(&mdev->kref); + rcu_read_unlock(); drbd_mdev_cleanup(mdev); + kref_put(&mdev->kref, &drbd_minor_destroy); + rcu_read_lock(); } - up_read(&drbd_cfg_rwsem); + rcu_read_unlock(); return 0; }