dlmlock.c

linux 内核源代码

		dlm_lockres_put(res);
	}
}

static void dlm_init_lock(struct dlm_lock *newlock, int type,
			  u8 node, u64 cookie)
{
	INIT_LIST_HEAD(&newlock->list);
	INIT_LIST_HEAD(&newlock->ast_list);
	INIT_LIST_HEAD(&newlock->bast_list);
	spin_lock_init(&newlock->spinlock);
	newlock->ml.type = type;
	newlock->ml.convert_type = LKM_IVMODE;
	newlock->ml.highest_blocked = LKM_IVMODE;
	newlock->ml.node = node;
	newlock->ml.pad1 = 0;
	newlock->ml.list = 0;
	newlock->ml.flags = 0;
	newlock->ast = NULL;
	newlock->bast = NULL;
	newlock->astdata = NULL;
	newlock->ml.cookie = cpu_to_be64(cookie);
	newlock->ast_pending = 0;
	newlock->bast_pending = 0;
	newlock->convert_pending = 0;
	newlock->lock_pending = 0;
	newlock->unlock_pending = 0;
	newlock->cancel_pending = 0;
	newlock->lksb_kernel_allocated = 0;

	kref_init(&newlock->lock_refs);
}

struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
			       struct dlm_lockstatus *lksb)
{
	struct dlm_lock *lock;
	int kernel_allocated = 0;

	lock = kzalloc(sizeof(*lock), GFP_NOFS);
	if (!lock)
		return NULL;

	if (!lksb) {
		/* zero memory only if kernel-allocated */
		lksb = kzalloc(sizeof(*lksb), GFP_NOFS);
		if (!lksb) {
			kfree(lock);
			return NULL;
		}
		kernel_allocated = 1;
	}

	dlm_init_lock(lock, type, node, cookie);
	if (kernel_allocated)
		lock->lksb_kernel_allocated = 1;
	lock->lksb = lksb;
	lksb->lockid = lock;
	return lock;
}

/* handler for lock creation net message
 * locking:
 *   caller needs:  none
 *   taken:         takes and drops res->spinlock
 *   held on exit:  none
 * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
 */
int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data,
			    void **ret_data)
{
	struct dlm_ctxt *dlm = data;
	struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
	struct dlm_lock_resource *res = NULL;
	struct dlm_lock *newlock = NULL;
	struct dlm_lockstatus *lksb = NULL;
	enum dlm_status status = DLM_NORMAL;
	char *name;
	unsigned int namelen;

	BUG_ON(!dlm);

	mlog_entry_void();

	if (!dlm_grab(dlm))
		return DLM_REJECTED;

	name = create->name;
	namelen = create->namelen;
	status = DLM_REJECTED;
	if (!dlm_domain_fully_joined(dlm)) {
		mlog(ML_ERROR, "Domain %s not fully joined, but node %u is "
		     "sending a create_lock message for lock %.*s!\n",
		     dlm->name, create->node_idx, namelen, name);
		dlm_error(status);
		goto leave;
	}

	status = DLM_IVBUFLEN;
	if (namelen > DLM_LOCKID_NAME_MAX) {
		dlm_error(status);
		goto leave;
	}

	status = DLM_SYSERR;
	newlock = dlm_new_lock(create->requested_type,
			       create->node_idx,
			       be64_to_cpu(create->cookie), NULL);
	if (!newlock) {
		dlm_error(status);
		goto leave;
	}

	lksb = newlock->lksb;

	if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
		lksb->flags |= DLM_LKSB_GET_LVB;
		mlog(0, "set DLM_LKSB_GET_LVB flag\n");
	}

	status = DLM_IVLOCKID;
	res = dlm_lookup_lockres(dlm, name, namelen);
	if (!res) {
		dlm_error(status);
		goto leave;
	}

	spin_lock(&res->spinlock);
	status = __dlm_lockres_state_to_status(res);
	spin_unlock(&res->spinlock);

	if (status != DLM_NORMAL) {
		mlog(0, "lockres recovering/migrating/in-progress\n");
		goto leave;
	}

	dlm_lock_attach_lockres(newlock, res);

	status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
leave:
	if (status != DLM_NORMAL)
		if (newlock)
			dlm_lock_put(newlock);

	if (res)
		dlm_lockres_put(res);

	dlm_put(dlm);

	return status;
}


/* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
{
	u64 tmpnode = node_num;

	/* shift single byte of node num into top 8 bits */
	tmpnode <<= 56;

	spin_lock(&dlm_cookie_lock);
	*cookie = (dlm_next_cookie | tmpnode);
	if (++dlm_next_cookie & 0xff00000000000000ull) {
		mlog(0, "This node's cookie will now wrap!\n");
		dlm_next_cookie = 1;
	}
	spin_unlock(&dlm_cookie_lock);
}

enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
			struct dlm_lockstatus *lksb, int flags,
			const char *name, int namelen, dlm_astlockfunc_t *ast,
			void *data, dlm_bastlockfunc_t *bast)
{
	enum dlm_status status;
	struct dlm_lock_resource *res = NULL;
	struct dlm_lock *lock = NULL;
	int convert = 0, recovery = 0;

	/* yes this function is a mess.
	 * TODO: clean this up.  lots of common code in the
	 *       lock and convert paths, especially in the retry blocks */
	if (!lksb) {
		dlm_error(DLM_BADARGS);
		return DLM_BADARGS;
	}

	status = DLM_BADPARAM;
	if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
		dlm_error(status);
		goto error;
	}

	if (flags & ~LKM_VALID_FLAGS) {
		dlm_error(status);
		goto error;
	}

	convert = (flags & LKM_CONVERT);
	recovery = (flags & LKM_RECOVERY);

	if (recovery &&
	    (!dlm_is_recovery_lock(name, namelen) || convert) ) {
		dlm_error(status);
		goto error;
	}
	if (convert && (flags & LKM_LOCAL)) {
		mlog(ML_ERROR, "strange LOCAL convert request!\n");
		goto error;
	}

	if (convert) {
		/* CONVERT request */

		/* if converting, must pass in a valid dlm_lock */
		lock = lksb->lockid;
		if (!lock) {
			mlog(ML_ERROR, "NULL lock pointer in convert "
			     "request\n");
			goto error;
		}

		res = lock->lockres;
		if (!res) {
			mlog(ML_ERROR, "NULL lockres pointer in convert "
			     "request\n");
			goto error;
		}
		dlm_lockres_get(res);

		/* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
	 	 * static after the original lock call.  convert requests will
		 * ensure that everything is the same, or return DLM_BADARGS.
	 	 * this means that DLM_DENIED_NOASTS will never be returned.
	 	 */
		if (lock->lksb != lksb || lock->ast != ast ||
		    lock->bast != bast || lock->astdata != data) {
			status = DLM_BADARGS;
			mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
			     "astdata=%p\n", lksb, ast, bast, data);
			mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
			     "astdata=%p\n", lock->lksb, lock->ast,
			     lock->bast, lock->astdata);
			goto error;
		}
retry_convert:
		dlm_wait_for_recovery(dlm);

		if (res->owner == dlm->node_num)
			status = dlmconvert_master(dlm, res, lock, flags, mode);
		else
			status = dlmconvert_remote(dlm, res, lock, flags, mode);
		if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
		    status == DLM_FORWARD) {
			/* for now, see how this works without sleeping
			 * and just retry right away.  I suspect the reco
			 * or migration will complete fast enough that
			 * no waiting will be necessary */
			mlog(0, "retrying convert with migration/recovery/"
			     "in-progress\n");
			msleep(100);
			goto retry_convert;
		}
	} else {
		u64 tmpcookie;

		/* LOCK request */
		status = DLM_BADARGS;
		if (!name) {
			dlm_error(status);
			goto error;
		}

		status = DLM_IVBUFLEN;
		if (namelen > DLM_LOCKID_NAME_MAX || namelen < 1) {
			dlm_error(status);
			goto error;
		}

		dlm_get_next_cookie(dlm->node_num, &tmpcookie);
		lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
		if (!lock) {
			dlm_error(status);
			goto error;
		}

		if (!recovery)
			dlm_wait_for_recovery(dlm);

		/* find or create the lock resource */
		res = dlm_get_lock_resource(dlm, name, namelen, flags);
		if (!res) {
			status = DLM_IVLOCKID;
			dlm_error(status);
			goto error;
		}

		mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
		mlog(0, "creating lock: lock=%p res=%p\n", lock, res);

		dlm_lock_attach_lockres(lock, res);
		lock->ast = ast;
		lock->bast = bast;
		lock->astdata = data;

retry_lock:
		if (flags & LKM_VALBLK) {
			mlog(0, "LKM_VALBLK passed by caller\n");

			/* LVB requests for non PR, PW or EX locks are
			 * ignored. */
			if (mode < LKM_PRMODE)
				flags &= ~LKM_VALBLK;
			else {
				flags |= LKM_GET_LVB;
				lock->lksb->flags |= DLM_LKSB_GET_LVB;
			}
		}

		if (res->owner == dlm->node_num)
			status = dlmlock_master(dlm, res, lock, flags);
		else
			status = dlmlock_remote(dlm, res, lock, flags);

		if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
		    status == DLM_FORWARD) {
			mlog(0, "retrying lock with migration/"
			     "recovery/in progress\n");
			msleep(100);
			/* no waiting for dlm_reco_thread */
			if (recovery) {
				if (status != DLM_RECOVERING)
					goto retry_lock;

				mlog(0, "%s: got RECOVERING "
				     "for $RECOVERY lock, master "
				     "was %u\n", dlm->name,
				     res->owner);
				/* wait to see the node go down, then
				 * drop down and allow the lockres to
				 * get cleaned up.  need to remaster. */
				dlm_wait_for_node_death(dlm, res->owner,
						DLM_NODE_DEATH_WAIT_MAX);
			} else {
				dlm_wait_for_recovery(dlm);
				goto retry_lock;
			}
		}

		if (status != DLM_NORMAL) {
			lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
			if (status != DLM_NOTQUEUED)
				dlm_error(status);
			goto error;
		}
	}

error:
	if (status != DLM_NORMAL) {
		if (lock && !convert)
			dlm_lock_put(lock);
		// this is kind of unnecessary
		lksb->status = status;
	}

	/* put lockres ref from the convert path
	 * or from dlm_get_lock_resource */
	if (res)
		dlm_lockres_put(res);

	return status;
}
EXPORT_SYMBOL_GPL(dlmlock);