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Commit 41d7db0a authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

[GFS2] Reduce size of struct gdlm_lock 



This patch removes the completion (which is rather large) from struct
gdlm_lock in favour of using the wait_on_bit() functions. We don't need
to add any extra fields to the structure to do this, so we save 32 bytes
(on x86_64) per structure. This adds up to quite a lot when we may
potentially have millions of these lock structures,

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
Acked-by: default avatarDavid Teigland <teigland@redhat.com>
parent cd81a4ba

fs/gfs2/locking/dlm/lock.c

+8 −3
Original line number Diff line number Diff line
@@ -174,7 +174,6 @@ static int gdlm_create_lp(struct gdlm_ls *ls, struct lm_lockname *name, 
	lp->cur = DLM_LOCK_IV;

	lp->lvb = NULL;

	lp->hold_null = NULL;

	init_completion(&lp->ast_wait);

	INIT_LIST_HEAD(&lp->clist);

	INIT_LIST_HEAD(&lp->blist);

	INIT_LIST_HEAD(&lp->delay_list);
@@ -399,6 +398,12 @@ static void gdlm_del_lvb(struct gdlm_lock *lp) 
	lp->lksb.sb_lvbptr = NULL;

}



static int gdlm_ast_wait(void *word)

{

	schedule();

	return 0;

}



/* This can do a synchronous dlm request (requiring a lock_dlm thread to get

   the completion) because gfs won't call hold_lvb() during a callback (from

   the context of a lock_dlm thread). */
@@ -424,10 +429,10 @@ static int hold_null_lock(struct gdlm_lock *lp) 
	lpn->lkf = DLM_LKF_VALBLK | DLM_LKF_EXPEDITE;

	set_bit(LFL_NOBAST, &lpn->flags);

	set_bit(LFL_INLOCK, &lpn->flags);

	set_bit(LFL_AST_WAIT, &lpn->flags);



	init_completion(&lpn->ast_wait);

	gdlm_do_lock(lpn);

	wait_for_completion(&lpn->ast_wait);

	wait_on_bit(&lpn->flags, LFL_AST_WAIT, gdlm_ast_wait, TASK_UNINTERRUPTIBLE);

	error = lpn->lksb.sb_status;

	if (error) {

		printk(KERN_INFO "lock_dlm: hold_null_lock dlm error %d\n",

fs/gfs2/locking/dlm/lock_dlm.h

+1 −1
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ enum { 
	LFL_NOBAST		= 10,

	LFL_HEADQUE		= 11,

	LFL_UNLOCK_DELETE	= 12,

	LFL_AST_WAIT		= 13,

};



struct gdlm_lock {
@@ -117,7 +118,6 @@ struct gdlm_lock { 
	unsigned long		flags;		/* lock_dlm flags LFL_ */



	int			bast_mode;	/* protected by async_lock */

	struct completion	ast_wait;



	struct list_head	clist;		/* complete */

	struct list_head	blist;		/* blocking */

fs/gfs2/locking/dlm/thread.c

+9 −2
Original line number Diff line number Diff line
@@ -44,6 +44,13 @@ static void process_blocking(struct gdlm_lock *lp, int bast_mode) 
	ls->fscb(ls->sdp, cb, &lp->lockname);

}



static void wake_up_ast(struct gdlm_lock *lp)

{

	clear_bit(LFL_AST_WAIT, &lp->flags);

	smp_mb__after_clear_bit();

	wake_up_bit(&lp->flags, LFL_AST_WAIT);

}



static void process_complete(struct gdlm_lock *lp)

{

	struct gdlm_ls *ls = lp->ls;
@@ -136,7 +143,7 @@ static void process_complete(struct gdlm_lock *lp) 
	 */



	if (test_and_clear_bit(LFL_SYNC_LVB, &lp->flags)) {

		complete(&lp->ast_wait);

		wake_up_ast(lp);

		return;

	}
@@ -214,7 +221,7 @@ out: 
	if (test_bit(LFL_INLOCK, &lp->flags)) {

		clear_bit(LFL_NOBLOCK, &lp->flags);

		lp->cur = lp->req;

		complete(&lp->ast_wait);

		wake_up_ast(lp);

		return;

	}