Date:   Fri, 9 Mar 2018 00:31:44 +0000
From:   "Dilger, Andreas" <andreas.dilger@...el.com>
To:     NeilBrown <neilb@...e.com>
CC:     "Drokin, Oleg" <oleg.drokin@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        James Simmons <jsimmons@...radead.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 15/17] staging: lustre: ptlrpc: move thread creation out
 of module initialization

On Mar 1, 2018, at 16:31, NeilBrown <neilb@...e.com> wrote:
> 
> When the ptlrpc module is loaded, it starts the pinger thread and
> calls LNetNIInit which starts various threads.
> 
> We don't need these threads until the module is actually being
> used, such as when a lustre filesystem is mounted.
> 
> So move the thread creation into new ptlrpc_inc_ref() (modeled on
> ptlrpcd_inc_ref()), and call that when needed, such as at mount time.

It looks like this is still done early enough in the mount sequence, so the
earlier "[06/17] get entropy from nid when nid set" action is still done
before the client UUID is generated in ll_init_sbi().

Reviewed-by: Andreas Dilger <andreas.dilger@...el.com>

> Signed-off-by: NeilBrown <neilb@...e.com>
> ---
> drivers/staging/lustre/lustre/include/lustre_net.h |    3 +
> drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c    |   12 ++++
> drivers/staging/lustre/lustre/llite/llite_lib.c    |   18 +++++-
> .../staging/lustre/lustre/ptlrpc/ptlrpc_module.c   |   56 +++++++++++++-------
> 4 files changed, 65 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/include/lustre_net.h b/drivers/staging/lustre/lustre/include/lustre_net.h
> index 108683c54127..d35ae0cda8d2 100644
> --- a/drivers/staging/lustre/lustre/include/lustre_net.h
> +++ b/drivers/staging/lustre/lustre/include/lustre_net.h
> @@ -1804,6 +1804,9 @@ int ptlrpc_register_rqbd(struct ptlrpc_request_buffer_desc *rqbd);
>  */
> void ptlrpc_request_committed(struct ptlrpc_request *req, int force);
> 
> +int ptlrpc_inc_ref(void);
> +void ptlrpc_dec_ref(void);
> +
> void ptlrpc_init_client(int req_portal, int rep_portal, char *name,
> 			struct ptlrpc_client *);
> struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid);
> diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
> index 58913e628124..c772c68e5a49 100644
> --- a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
> +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
> @@ -869,6 +869,10 @@ int ldlm_get_ref(void)
> {
> 	int rc = 0;
> 
> +	rc = ptlrpc_inc_ref();
> +	if (rc)
> +		return rc;
> +
> 	mutex_lock(&ldlm_ref_mutex);
> 	if (++ldlm_refcount == 1) {
> 		rc = ldlm_setup();
> @@ -877,14 +881,18 @@ int ldlm_get_ref(void)
> 	}
> 	mutex_unlock(&ldlm_ref_mutex);
> 
> +	if (rc)
> +		ptlrpc_dec_ref();
> +
> 	return rc;
> }
> 
> void ldlm_put_ref(void)
> {
> +	int rc = 0;
> 	mutex_lock(&ldlm_ref_mutex);
> 	if (ldlm_refcount == 1) {
> -		int rc = ldlm_cleanup();
> +		rc = ldlm_cleanup();
> 
> 		if (rc)
> 			CERROR("ldlm_cleanup failed: %d\n", rc);
> @@ -894,6 +902,8 @@ void ldlm_put_ref(void)
> 		ldlm_refcount--;
> 	}
> 	mutex_unlock(&ldlm_ref_mutex);
> +	if (!rc)
> +		ptlrpc_dec_ref();
> }
> 
> static ssize_t cancel_unused_locks_before_replay_show(struct kobject *kobj,
> diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
> index 844182ad7dd7..706b14bf8981 100644
> --- a/drivers/staging/lustre/lustre/llite/llite_lib.c
> +++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
> @@ -879,9 +879,15 @@ int ll_fill_super(struct super_block *sb)
> 
> 	CDEBUG(D_VFSTRACE, "VFS Op: sb %p\n", sb);
> 
> +	err = ptlrpc_inc_ref();
> +	if (err)
> +		return err;
> +
> 	cfg = kzalloc(sizeof(*cfg), GFP_NOFS);
> -	if (!cfg)
> -		return -ENOMEM;
> +	if (!cfg) {
> +		err = -ENOMEM;
> +		goto out_put;
> +	}
> 
> 	try_module_get(THIS_MODULE);
> 
> @@ -891,7 +897,8 @@ int ll_fill_super(struct super_block *sb)
> 	if (!sbi) {
> 		module_put(THIS_MODULE);
> 		kfree(cfg);
> -		return -ENOMEM;
> +		err = -ENOMEM;
> +		goto out_put;
> 	}
> 
> 	err = ll_options(lsi->lsi_lmd->lmd_opts, &sbi->ll_flags);
> @@ -958,6 +965,9 @@ int ll_fill_super(struct super_block *sb)
> 		LCONSOLE_WARN("Mounted %s\n", profilenm);
> 
> 	kfree(cfg);
> +out_put:
> +	if (err)
> +		ptlrpc_dec_ref();
> 	return err;
> } /* ll_fill_super */
> 
> @@ -1028,6 +1038,8 @@ void ll_put_super(struct super_block *sb)
> 	cl_env_cache_purge(~0);
> 
> 	module_put(THIS_MODULE);
> +
> +	ptlrpc_dec_ref();
> } /* client_put_super */
> 
> struct inode *ll_inode_from_resource_lock(struct ldlm_lock *lock)
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_module.c b/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_module.c
> index 131fc6d9646e..38923418669f 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_module.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_module.c
> @@ -45,6 +45,42 @@ extern spinlock_t ptlrpc_last_xid_lock;
> extern spinlock_t ptlrpc_rs_debug_lock;
> #endif
> 
> +DEFINE_MUTEX(ptlrpc_startup);
> +static int ptlrpc_active = 0;
> +
> +int ptlrpc_inc_ref(void)
> +{
> +	int rc = 0;
> +
> +	mutex_lock(&ptlrpc_startup);
> +	if (ptlrpc_active++ == 0) {
> +		ptlrpc_put_connection_superhack = ptlrpc_connection_put;
> +
> +		rc = ptlrpc_init_portals();
> +		if (!rc) {
> +			rc= ptlrpc_start_pinger();
> +			if (rc)
> +				ptlrpc_exit_portals();
> +		}
> +		if (rc)
> +			ptlrpc_active--;
> +	}
> +	mutex_unlock(&ptlrpc_startup);
> +	return rc;
> +}
> +EXPORT_SYMBOL(ptlrpc_inc_ref);
> +
> +void ptlrpc_dec_ref(void)
> +{
> +	mutex_lock(&ptlrpc_startup);
> +	if (--ptlrpc_active == 0) {
> +		ptlrpc_stop_pinger();
> +		ptlrpc_exit_portals();
> +	}
> +	mutex_unlock(&ptlrpc_startup);
> +}
> +EXPORT_SYMBOL(ptlrpc_dec_ref);
> +
> static int __init ptlrpc_init(void)
> {
> 	int rc, cleanup_phase = 0;
> @@ -71,24 +107,12 @@ static int __init ptlrpc_init(void)
> 	if (rc)
> 		goto cleanup;
> 
> -	cleanup_phase = 2;
> -	rc = ptlrpc_init_portals();
> -	if (rc)
> -		goto cleanup;
> -
> 	cleanup_phase = 3;
> 
> 	rc = ptlrpc_connection_init();
> 	if (rc)
> 		goto cleanup;
> 
> -	cleanup_phase = 4;
> -	ptlrpc_put_connection_superhack = ptlrpc_connection_put;
> -
> -	rc = ptlrpc_start_pinger();
> -	if (rc)
> -		goto cleanup;
> -
> 	cleanup_phase = 5;
> 	rc = ldlm_init();
> 	if (rc)
> @@ -122,15 +146,9 @@ static int __init ptlrpc_init(void)
> 		ldlm_exit();
> 		/* Fall through */
> 	case 5:
> -		ptlrpc_stop_pinger();
> -		/* Fall through */
> -	case 4:
> 		ptlrpc_connection_fini();
> 		/* Fall through */
> 	case 3:
> -		ptlrpc_exit_portals();
> -		/* Fall through */
> -	case 2:
> 		ptlrpc_request_cache_fini();
> 		/* Fall through */
> 	case 1:
> @@ -150,8 +168,6 @@ static void __exit ptlrpc_exit(void)
> 	ptlrpc_nrs_fini();
> 	sptlrpc_fini();
> 	ldlm_exit();
> -	ptlrpc_stop_pinger();
> -	ptlrpc_exit_portals();
> 	ptlrpc_request_cache_fini();
> 	ptlrpc_hr_fini();
> 	ptlrpc_connection_fini();
> 
> 

Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel Corporation

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