[Ocfs2-devel] [PATCH] ocfs2/dlm: dynamically allocate lvb for dlm_lock_resource

[Sunil Mushran <sunil.mushran@oracle.com>]

On 08/21/2010 04:13 PM, Wengang Wang wrote:
> Not all dlm_lock_resource use lvb. It's a waste of memory for those
> dlm_lock_resources since lvb is a "char lvb[64];".
>
> This patch allocates lvb for dlm_lock_resources who use lvb.
>
> Without the patch applied,
> [wwg at cool linux-2.6]$ egrep "o2dlm_lockres" /proc/slabinfo
> o2dlm_lockres         42     42    256   32    2 : tunables    0    0    0 : slabdata      2      2      0
>
> After patch applied,
> [wwg at cool linux-2.6]$ egrep "o2dlm_lockres" /proc/slabinfo
> o2dlm_lockres         42     42    192   21    1 : tunables    0    0    0 : slabdata      2      2      0
>
> #that's on i686.
>    

nice.

> Signed-off-by: Wengang Wang<wen.gang.wang@oracle.com>
> ---
>   fs/ocfs2/dlm/dlmast.c    |    2 ++
>   fs/ocfs2/dlm/dlmcommon.h |    3 ++-
>   fs/ocfs2/dlm/dlmlock.c   |    6 ++++++
>   fs/ocfs2/dlm/dlmmaster.c |   31 ++++++++++++++++++++++++++++---
>   4 files changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmast.c b/fs/ocfs2/dlm/dlmast.c
> index f449991..fe272b1 100644
> --- a/fs/ocfs2/dlm/dlmast.c
> +++ b/fs/ocfs2/dlm/dlmast.c
> @@ -191,6 +191,8 @@ static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
>   			mlog(0, "getting lvb from lockres for %s node\n",
>   				  lock->ml.node == dlm->node_num ? "master" :
>   				  "remote");
> +			mlog_bug_on_msg(!res->lvb, "lockname : %.*s\n",
> +					res->lockname.len, res->lockname.name);
>   			memcpy(lksb->lvb, res->lvb, DLM_LVB_LEN);
>   		}
>    

Move this to the top of the function. We want to catch this bug as
early as possible.

>   		/* Do nothing for lvb put requests - they should be done in
> diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
> index 4b6ae2c..49e6492 100644
> --- a/fs/ocfs2/dlm/dlmcommon.h
> +++ b/fs/ocfs2/dlm/dlmcommon.h
> @@ -329,7 +329,7 @@ struct dlm_lock_resource
>   	wait_queue_head_t wq;
>   	u8  owner;              //node which owns the lock resource, or unknown
>   	u16 state;
> -	char lvb[DLM_LVB_LEN];
> +	char *lvb;
>   	unsigned int inflight_locks;
>   	unsigned long refmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
>   };
> @@ -1033,6 +1033,7 @@ void dlm_clean_master_list(struct dlm_ctxt *dlm,
>   int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock);
>   int __dlm_lockres_has_locks(struct dlm_lock_resource *res);
>   int __dlm_lockres_unused(struct dlm_lock_resource *res);
> +char *dlm_alloc_lvb(char **lvb);
>
>   static inline const char * dlm_lock_mode_name(int mode)
>   {
> diff --git a/fs/ocfs2/dlm/dlmlock.c b/fs/ocfs2/dlm/dlmlock.c
> index 69cf369..5c7ece7 100644
> --- a/fs/ocfs2/dlm/dlmlock.c
> +++ b/fs/ocfs2/dlm/dlmlock.c
> @@ -425,6 +425,12 @@ static void dlm_init_lock(struct dlm_lock *newlock, int type,
>   	kref_init(&newlock->lock_refs);
>   }
>
> +char *dlm_alloc_lvb(char **lvb)
> +{
> +	*lvb = kzalloc(DLM_LVB_LEN, GFP_NOFS);
> +	return *lvb;
> +}
>    

Scrap this function. Do the kzalloc() in dlm_new_lockres() itself.
This way we do allocs for a lockres in one location.

> +
>   struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
>   			       struct dlm_lockstatus *lksb)
>   {
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index ffb4c68..77315a4 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -545,6 +545,7 @@ static void dlm_lockres_release(struct kref *kref)
>
>   	kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
>
> +	kfree(res->lvb);
>   	kmem_cache_free(dlm_lockres_cache, res);
>   }
>
> @@ -553,7 +554,20 @@ void dlm_lockres_put(struct dlm_lock_resource *res)
>   	kref_put(&res->refs, dlm_lockres_release);
>   }
>
> -static void dlm_init_lockres(struct dlm_ctxt *dlm,
> +static int dlm_lockres_uses_lvb(struct dlm_lock_resource *res)
> +{
> +	switch (res->lockname.name[0]) {
> +	case 'M':
> +	case 'Q':
> +	case 'R':
> +	case 'P':
> +		return 1;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static int dlm_init_lockres(struct dlm_ctxt *dlm,
>   			     struct dlm_lock_resource *res,
>   			     const char *name, unsigned int namelen)
>   {
> @@ -603,8 +617,16 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
>   	list_add_tail(&res->tracking,&dlm->tracking_list);
>   	spin_unlock(&dlm->spinlock);
>
> -	memset(res->lvb, 0, DLM_LVB_LEN);
> +	if (dlm_lockres_uses_lvb(res)) {
> +		if (!dlm_alloc_lvb(&res->lvb)) {
> +			mlog(ML_ERROR, "no memory for lvb\n");
> +			return -ENOMEM;
> +		}
> +	} else {
> +		res->lvb = NULL;
> +	}
>   	memset(res->refmap, 0, sizeof(res->refmap));
> +	return 0;
>   }
>
>   struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
> @@ -612,6 +634,7 @@ struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
>   				   unsigned int namelen)
>   {
>   	struct dlm_lock_resource *res = NULL;
> +	int ret;
>
>   	res = kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
>   	if (!res)
> @@ -621,7 +644,9 @@ struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
>   	if (!res->lockname.name)
>   		goto error;
>
> -	dlm_init_lockres(dlm, res, name, namelen);
> +	ret = dlm_init_lockres(dlm, res, name, namelen);
> +	if (ret)
> +		goto error;
>   	return res;
>
>   error:
>