[GFS2] The lock modules for GFS2

This patch contains the pluggable locking modules
for GFS2.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 359 insertions, 0 deletions

diff --git a/fs/gfs2/locking/dlm/thread.c b/fs/gfs2/locking/dlm/thread.c
new file mode 100644
index 000000000000..22bbe6d3a5ae
--- /dev/null
+++ b/fs/gfs2/locking/dlm/thread.c
@@ -0,0 +1,359 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**
+**  This copyrighted material is made available to anyone wishing to use,
+**  modify, copy, or redistribute it subject to the terms and conditions
+**  of the GNU General Public License v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+#include "lock_dlm.h"
+
+/* A lock placed on this queue is re-submitted to DLM as soon as the lock_dlm
+   thread gets to it. */
+
+static void queue_submit(struct gdlm_lock *lp)
+{
+	struct gdlm_ls *ls = lp->ls;
+
+	spin_lock(&ls->async_lock);
+	list_add_tail(&lp->delay_list, &ls->submit);
+	spin_unlock(&ls->async_lock);
+	wake_up(&ls->thread_wait);
+}
+
+static void process_submit(struct gdlm_lock *lp)
+{
+	gdlm_do_lock(lp, NULL);
+}
+
+static void process_blocking(struct gdlm_lock *lp, int bast_mode)
+{
+	struct gdlm_ls *ls = lp->ls;
+	unsigned int cb;
+
+	switch (gdlm_make_lmstate(bast_mode)) {
+	case LM_ST_EXCLUSIVE:
+		cb = LM_CB_NEED_E;
+		break;
+	case LM_ST_DEFERRED:
+		cb = LM_CB_NEED_D;
+		break;
+	case LM_ST_SHARED:
+		cb = LM_CB_NEED_S;
+		break;
+	default:
+		GDLM_ASSERT(0, printk("unknown bast mode %u\n",lp->bast_mode););
+	}
+
+	ls->fscb(ls->fsdata, cb, &lp->lockname);
+}
+
+static void process_complete(struct gdlm_lock *lp)
+{
+	struct gdlm_ls *ls = lp->ls;
+	struct lm_async_cb acb;
+	int16_t prev_mode = lp->cur;
+
+	memset(&acb, 0, sizeof(acb));
+
+	if (lp->lksb.sb_status == -DLM_ECANCEL) {
+		log_all("complete dlm cancel %x,%"PRIx64" flags %lx",
+			lp->lockname.ln_type, lp->lockname.ln_number,
+			lp->flags);
+
+		lp->req = lp->cur;
+		acb.lc_ret |= LM_OUT_CANCELED;
+		if (lp->cur == DLM_LOCK_IV)
+			lp->lksb.sb_lkid = 0;
+		goto out;
+	}
+
+	if (test_and_clear_bit(LFL_DLM_UNLOCK, &lp->flags)) {
+		if (lp->lksb.sb_status != -DLM_EUNLOCK) {
+			log_all("unlock sb_status %d %x,%"PRIx64" flags %lx",
+				lp->lksb.sb_status, lp->lockname.ln_type,
+				lp->lockname.ln_number, lp->flags);
+			return;
+		}
+
+		lp->cur = DLM_LOCK_IV;
+		lp->req = DLM_LOCK_IV;
+		lp->lksb.sb_lkid = 0;
+
+		if (test_and_clear_bit(LFL_UNLOCK_DELETE, &lp->flags)) {
+			gdlm_delete_lp(lp);
+			return;
+		}
+		goto out;
+	}
+
+	if (lp->lksb.sb_flags & DLM_SBF_VALNOTVALID)
+		memset(lp->lksb.sb_lvbptr, 0, GDLM_LVB_SIZE);
+
+	if (lp->lksb.sb_flags & DLM_SBF_ALTMODE) {
+		if (lp->req == DLM_LOCK_PR)
+			lp->req = DLM_LOCK_CW;
+		else if (lp->req == DLM_LOCK_CW)
+			lp->req = DLM_LOCK_PR;
+	}
+
+	/*
+	 * A canceled lock request.  The lock was just taken off the delayed
+	 * list and was never even submitted to dlm.
+	 */
+
+	if (test_and_clear_bit(LFL_CANCEL, &lp->flags)) {
+		log_all("complete internal cancel %x,%"PRIx64"",
+			lp->lockname.ln_type, lp->lockname.ln_number);
+		lp->req = lp->cur;
+		acb.lc_ret |= LM_OUT_CANCELED;
+		goto out;
+	}
+
+	/*
+	 * An error occured.
+	 */
+
+	if (lp->lksb.sb_status) {
+		/* a "normal" error */
+		if ((lp->lksb.sb_status == -EAGAIN) &&
+		    (lp->lkf & DLM_LKF_NOQUEUE)) {
+			lp->req = lp->cur;
+			if (lp->cur == DLM_LOCK_IV)
+				lp->lksb.sb_lkid = 0;
+			goto out;
+		}
+
+		/* this could only happen with cancels I think */
+		log_all("ast sb_status %d %x,%"PRIx64" flags %lx",
+			lp->lksb.sb_status, lp->lockname.ln_type,
+			lp->lockname.ln_number, lp->flags);
+		return;
+	}
+
+	/*
+	 * This is an AST for an EX->EX conversion for sync_lvb from GFS.
+	 */
+
+	if (test_and_clear_bit(LFL_SYNC_LVB, &lp->flags)) {
+		complete(&lp->ast_wait);
+		return;
+	}
+
+	/*
+	 * A lock has been demoted to NL because it initially completed during
+	 * BLOCK_LOCKS.  Now it must be requested in the originally requested
+	 * mode.
+	 */
+
+	if (test_and_clear_bit(LFL_REREQUEST, &lp->flags)) {
+		GDLM_ASSERT(lp->req == DLM_LOCK_NL,);
+		GDLM_ASSERT(lp->prev_req > DLM_LOCK_NL,);
+
+		lp->cur = DLM_LOCK_NL;
+		lp->req = lp->prev_req;
+		lp->prev_req = DLM_LOCK_IV;
+		lp->lkf &= ~DLM_LKF_CONVDEADLK;
+
+		set_bit(LFL_NOCACHE, &lp->flags);
+
+		if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
+		    !test_bit(LFL_NOBLOCK, &lp->flags))
+			gdlm_queue_delayed(lp);
+		else
+			queue_submit(lp);
+		return;
+	}
+
+	/*
+	 * A request is granted during dlm recovery.  It may be granted
+	 * because the locks of a failed node were cleared.  In that case,
+	 * there may be inconsistent data beneath this lock and we must wait
+	 * for recovery to complete to use it.  When gfs recovery is done this
+	 * granted lock will be converted to NL and then reacquired in this
+	 * granted state.
+	 */
+
+	if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
+	    !test_bit(LFL_NOBLOCK, &lp->flags) &&
+	    lp->req != DLM_LOCK_NL) {
+
+		lp->cur = lp->req;
+		lp->prev_req = lp->req;
+		lp->req = DLM_LOCK_NL;
+		lp->lkf |= DLM_LKF_CONVERT;
+		lp->lkf &= ~DLM_LKF_CONVDEADLK;
+
+		log_debug("rereq %x,%"PRIx64" id %x %d,%d",
+			  lp->lockname.ln_type, lp->lockname.ln_number,
+			  lp->lksb.sb_lkid, lp->cur, lp->req);
+
+		set_bit(LFL_REREQUEST, &lp->flags);
+		queue_submit(lp);
+		return;
+	}
+
+	/*
+	 * DLM demoted the lock to NL before it was granted so GFS must be
+	 * told it cannot cache data for this lock.
+	 */
+
+	if (lp->lksb.sb_flags & DLM_SBF_DEMOTED)
+		set_bit(LFL_NOCACHE, &lp->flags);
+
+ out:
+	/*
+	 * This is an internal lock_dlm lock
+	 */
+
+	if (test_bit(LFL_INLOCK, &lp->flags)) {
+		clear_bit(LFL_NOBLOCK, &lp->flags);
+		lp->cur = lp->req;
+		complete(&lp->ast_wait);
+		return;
+	}
+
+	/*
+	 * Normal completion of a lock request.  Tell GFS it now has the lock.
+	 */
+
+	clear_bit(LFL_NOBLOCK, &lp->flags);
+	lp->cur = lp->req;
+
+	acb.lc_name = lp->lockname;
+	acb.lc_ret |= gdlm_make_lmstate(lp->cur);
+
+	if (!test_and_clear_bit(LFL_NOCACHE, &lp->flags) &&
+	    (lp->cur > DLM_LOCK_NL) && (prev_mode > DLM_LOCK_NL))
+		acb.lc_ret |= LM_OUT_CACHEABLE;
+
+	ls->fscb(ls->fsdata, LM_CB_ASYNC, &acb);
+}
+
+static inline int no_work(struct gdlm_ls *ls, int blocking)
+{
+	int ret;
+
+	spin_lock(&ls->async_lock);
+	ret = list_empty(&ls->complete) && list_empty(&ls->submit);
+	if (ret && blocking)
+		ret = list_empty(&ls->blocking);
+	spin_unlock(&ls->async_lock);
+
+	return ret;
+}
+
+static inline int check_drop(struct gdlm_ls *ls)
+{
+	if (!ls->drop_locks_count)
+		return 0;
+
+	if (time_after(jiffies, ls->drop_time + ls->drop_locks_period * HZ)) {
+		ls->drop_time = jiffies;
+		if (ls->all_locks_count >= ls->drop_locks_count)
+			return 1;
+	}
+	return 0;
+}
+
+static int gdlm_thread(void *data)
+{
+	struct gdlm_ls *ls = (struct gdlm_ls *) data;
+	struct gdlm_lock *lp = NULL;
+	int blist = 0;
+	uint8_t complete, blocking, submit, drop;
+	DECLARE_WAITQUEUE(wait, current);
+
+	/* Only thread1 is allowed to do blocking callbacks since gfs
+	   may wait for a completion callback within a blocking cb. */
+
+	if (current == ls->thread1)
+		blist = 1;
+
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		add_wait_queue(&ls->thread_wait, &wait);
+		if (no_work(ls, blist))
+			schedule();
+		remove_wait_queue(&ls->thread_wait, &wait);
+		set_current_state(TASK_RUNNING);
+
+		complete = blocking = submit = drop = 0;
+
+		spin_lock(&ls->async_lock);
+
+		if (blist && !list_empty(&ls->blocking)) {
+			lp = list_entry(ls->blocking.next, struct gdlm_lock,
+					blist);
+			list_del_init(&lp->blist);
+			blocking = lp->bast_mode;
+			lp->bast_mode = 0;
+		} else if (!list_empty(&ls->complete)) {
+			lp = list_entry(ls->complete.next, struct gdlm_lock,
+					clist);
+			list_del_init(&lp->clist);
+			complete = 1;
+		} else if (!list_empty(&ls->submit)) {
+			lp = list_entry(ls->submit.next, struct gdlm_lock,
+					delay_list);
+			list_del_init(&lp->delay_list);
+			submit = 1;
+		}
+
+		drop = check_drop(ls);
+		spin_unlock(&ls->async_lock);
+
+		if (complete)
+			process_complete(lp);
+
+		else if (blocking)
+			process_blocking(lp, blocking);
+
+		else if (submit)
+			process_submit(lp);
+
+		if (drop)
+			ls->fscb(ls->fsdata, LM_CB_DROPLOCKS, NULL);
+
+		schedule();
+	}
+
+	return 0;
+}
+
+int gdlm_init_threads(struct gdlm_ls *ls)
+{
+	struct task_struct *p;
+	int error;
+
+	p = kthread_run(gdlm_thread, ls, "lock_dlm1");
+	error = IS_ERR(p);
+	if (error) {
+		log_all("can't start lock_dlm1 thread %d", error);
+		return error;
+	}
+	ls->thread1 = p;
+
+	p = kthread_run(gdlm_thread, ls, "lock_dlm2");
+	error = IS_ERR(p);
+	if (error) {
+		log_all("can't start lock_dlm2 thread %d", error);
+		kthread_stop(ls->thread1);
+		return error;
+	}
+	ls->thread2 = p;
+
+	return 0;
+}
+
+void gdlm_release_threads(struct gdlm_ls *ls)
+{
+	kthread_stop(ls->thread1);
+	kthread_stop(ls->thread2);
+}
+