[Cluster-devel] [PATCH RESEND dlm/next 0/2] dlm: resend list iterator patches

[Cluster-devel] [PATCH RESEND dlm/next 0/2] dlm: resend list iterator patches

[Alexander Aring]

Hi,

this is a resend of Jakob Koschels list iterator patches rebased on
current pending dlm patches. We had a lot of change in the plock
handling of dlm.

*little change that lkb is named "big_lkb" to remain the "big lock"
information in variable name of function recover_lvb(). Otherwise it
should be the same.

Thanks.

- Alex

Jakob Koschel (2):
  dlm: remove usage of list iterator for list_add() after the loop body
  dlm: replace usage of found with dedicated list iterator variable

 fs/dlm/lock.c    | 65 ++++++++++++++++++++++++------------------------
 fs/dlm/plock.c   | 24 +++++++++---------
 fs/dlm/recover.c | 39 ++++++++++++++---------------
 3 files changed, 64 insertions(+), 64 deletions(-)

-- 
2.31.1

[Cluster-devel] [PATCH RESEND dlm/next 1/2] dlm: remove usage of list iterator for list_add() after the loop body

[Alexander Aring]

From: Jakob Koschel <jakobkoschel@gmail.com>

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Before, the code implicitly used the head when no element was found
when using &pos->list. Since the new variable is only set if an
element was found, the list_add() is performed within the loop
and only done after the loop if it is done on the list head directly.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w at mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lock.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index f5330e58d1fc..20eca2261711 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1321,13 +1321,17 @@ static inline void unhold_lkb(struct dlm_lkb *lkb)
 static void lkb_add_ordered(struct list_head *new, struct list_head *head,
 			    int mode)
 {
-	struct dlm_lkb *lkb = NULL;
+	struct dlm_lkb *lkb = NULL, *iter;
 
-	list_for_each_entry(lkb, head, lkb_statequeue)
-		if (lkb->lkb_rqmode < mode)
+	list_for_each_entry(iter, head, lkb_statequeue)
+		if (iter->lkb_rqmode < mode) {
+			lkb = iter;
+			list_add_tail(new, &iter->lkb_statequeue);
 			break;
+		}
 
-	__list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue);
+	if (!lkb)
+		list_add_tail(new, head);
 }
 
 /* add/remove lkb to rsb's grant/convert/wait queue */
-- 
2.31.1

[Cluster-devel] [PATCH RESEND dlm/next 2/2] dlm: replace usage of found with dedicated list iterator variable

[Alexander Aring]

From: Jakob Koschel <jakobkoschel@gmail.com>

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].

This removes the need to use a found variable and simply checking if
the variable was set, can determine if the break/goto was hit.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w at mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lock.c    | 53 +++++++++++++++++++++++-------------------------
 fs/dlm/plock.c   | 24 +++++++++++-----------
 fs/dlm/recover.c | 39 +++++++++++++++++------------------
 3 files changed, 56 insertions(+), 60 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 20eca2261711..1899bb266e2e 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1885,7 +1885,7 @@ static void del_timeout(struct dlm_lkb *lkb)
 void dlm_scan_timeout(struct dlm_ls *ls)
 {
 	struct dlm_rsb *r;
-	struct dlm_lkb *lkb;
+	struct dlm_lkb *lkb = NULL, *iter;
 	int do_cancel, do_warn;
 	s64 wait_us;
 
@@ -1896,27 +1896,28 @@ void dlm_scan_timeout(struct dlm_ls *ls)
 		do_cancel = 0;
 		do_warn = 0;
 		mutex_lock(&ls->ls_timeout_mutex);
-		list_for_each_entry(lkb, &ls->ls_timeout, lkb_time_list) {
+		list_for_each_entry(iter, &ls->ls_timeout, lkb_time_list) {
 
 			wait_us = ktime_to_us(ktime_sub(ktime_get(),
-					      		lkb->lkb_timestamp));
+							iter->lkb_timestamp));
 
-			if ((lkb->lkb_exflags & DLM_LKF_TIMEOUT) &&
-			    wait_us >= (lkb->lkb_timeout_cs * 10000))
+			if ((iter->lkb_exflags & DLM_LKF_TIMEOUT) &&
+			    wait_us >= (iter->lkb_timeout_cs * 10000))
 				do_cancel = 1;
 
-			if ((lkb->lkb_flags & DLM_IFL_WATCH_TIMEWARN) &&
+			if ((iter->lkb_flags & DLM_IFL_WATCH_TIMEWARN) &&
 			    wait_us >= dlm_config.ci_timewarn_cs * 10000)
 				do_warn = 1;
 
 			if (!do_cancel && !do_warn)
 				continue;
-			hold_lkb(lkb);
+			hold_lkb(iter);
+			lkb = iter;
 			break;
 		}
 		mutex_unlock(&ls->ls_timeout_mutex);
 
-		if (!do_cancel && !do_warn)
+		if (!lkb)
 			break;
 
 		r = lkb->lkb_resource;
@@ -5292,21 +5293,18 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
 
 static struct dlm_lkb *find_resend_waiter(struct dlm_ls *ls)
 {
-	struct dlm_lkb *lkb;
-	int found = 0;
+	struct dlm_lkb *lkb = NULL, *iter;
 
 	mutex_lock(&ls->ls_waiters_mutex);
-	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
-		if (lkb->lkb_flags & DLM_IFL_RESEND) {
-			hold_lkb(lkb);
-			found = 1;
+	list_for_each_entry(iter, &ls->ls_waiters, lkb_wait_reply) {
+		if (iter->lkb_flags & DLM_IFL_RESEND) {
+			hold_lkb(iter);
+			lkb = iter;
 			break;
 		}
 	}
 	mutex_unlock(&ls->ls_waiters_mutex);
 
-	if (!found)
-		lkb = NULL;
 	return lkb;
 }
 
@@ -5964,37 +5962,36 @@ int dlm_user_adopt_orphan(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
 		     int mode, uint32_t flags, void *name, unsigned int namelen,
 		     unsigned long timeout_cs, uint32_t *lkid)
 {
-	struct dlm_lkb *lkb;
+	struct dlm_lkb *lkb = NULL, *iter;
 	struct dlm_user_args *ua;
 	int found_other_mode = 0;
-	int found = 0;
 	int rv = 0;
 
 	mutex_lock(&ls->ls_orphans_mutex);
-	list_for_each_entry(lkb, &ls->ls_orphans, lkb_ownqueue) {
-		if (lkb->lkb_resource->res_length != namelen)
+	list_for_each_entry(iter, &ls->ls_orphans, lkb_ownqueue) {
+		if (iter->lkb_resource->res_length != namelen)
 			continue;
-		if (memcmp(lkb->lkb_resource->res_name, name, namelen))
+		if (memcmp(iter->lkb_resource->res_name, name, namelen))
 			continue;
-		if (lkb->lkb_grmode != mode) {
+		if (iter->lkb_grmode != mode) {
 			found_other_mode = 1;
 			continue;
 		}
 
-		found = 1;
-		list_del_init(&lkb->lkb_ownqueue);
-		lkb->lkb_flags &= ~DLM_IFL_ORPHAN;
-		*lkid = lkb->lkb_id;
+		lkb = iter;
+		list_del_init(&iter->lkb_ownqueue);
+		iter->lkb_flags &= ~DLM_IFL_ORPHAN;
+		*lkid = iter->lkb_id;
 		break;
 	}
 	mutex_unlock(&ls->ls_orphans_mutex);
 
-	if (!found && found_other_mode) {
+	if (!lkb && found_other_mode) {
 		rv = -EAGAIN;
 		goto out;
 	}
 
-	if (!found) {
+	if (!lkb) {
 		rv = -ENOENT;
 		goto out;
 	}
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c
index 16241fe6ac3c..0993eebf2060 100644
--- a/fs/dlm/plock.c
+++ b/fs/dlm/plock.c
@@ -407,9 +407,9 @@ static ssize_t dev_read(struct file *file, char __user *u, size_t count,
 static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
 			 loff_t *ppos)
 {
+	struct plock_op *op = NULL, *iter;
 	struct dlm_plock_info info;
-	struct plock_op *op;
-	int found = 0, do_callback = 0;
+	int do_callback = 0;
 
 	if (count != sizeof(info))
 		return -EINVAL;
@@ -421,23 +421,23 @@ static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
 		return -EINVAL;
 
 	spin_lock(&ops_lock);
-	list_for_each_entry(op, &recv_list, list) {
-		if (op->info.fsid == info.fsid &&
-		    op->info.number == info.number &&
-		    op->info.owner == info.owner) {
-			list_del_init(&op->list);
-			memcpy(&op->info, &info, sizeof(info));
-			if (op->data)
+	list_for_each_entry(iter, &recv_list, list) {
+		if (iter->info.fsid == info.fsid &&
+		    iter->info.number == info.number &&
+		    iter->info.owner == info.owner) {
+			list_del_init(&iter->list);
+			memcpy(&iter->info, &info, sizeof(info));
+			if (iter->data)
 				do_callback = 1;
 			else
-				op->done = 1;
-			found = 1;
+				iter->done = 1;
+			op = iter;
 			break;
 		}
 	}
 	spin_unlock(&ops_lock);
 
-	if (found) {
+	if (op) {
 		if (do_callback)
 			dlm_plock_callback(op);
 		else
diff --git a/fs/dlm/recover.c b/fs/dlm/recover.c
index dfd504bf1ecf..ccff1791803f 100644
--- a/fs/dlm/recover.c
+++ b/fs/dlm/recover.c
@@ -732,10 +732,9 @@ void dlm_recovered_lock(struct dlm_rsb *r)
 
 static void recover_lvb(struct dlm_rsb *r)
 {
-	struct dlm_lkb *lkb, *high_lkb = NULL;
+	struct dlm_lkb *big_lkb = NULL, *iter, *high_lkb = NULL;
 	uint32_t high_seq = 0;
 	int lock_lvb_exists = 0;
-	int big_lock_exists = 0;
 	int lvblen = r->res_ls->ls_lvblen;
 
 	if (!rsb_flag(r, RSB_NEW_MASTER2) &&
@@ -751,37 +750,37 @@ static void recover_lvb(struct dlm_rsb *r)
 	/* we are the new master, so figure out if VALNOTVALID should
 	   be set, and set the rsb lvb from the best lkb available. */
 
-	list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
-		if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
+	list_for_each_entry(iter, &r->res_grantqueue, lkb_statequeue) {
+		if (!(iter->lkb_exflags & DLM_LKF_VALBLK))
 			continue;
 
 		lock_lvb_exists = 1;
 
-		if (lkb->lkb_grmode > DLM_LOCK_CR) {
-			big_lock_exists = 1;
+		if (iter->lkb_grmode > DLM_LOCK_CR) {
+			big_lkb = iter;
 			goto setflag;
 		}
 
-		if (((int)lkb->lkb_lvbseq - (int)high_seq) >= 0) {
-			high_lkb = lkb;
-			high_seq = lkb->lkb_lvbseq;
+		if (((int)iter->lkb_lvbseq - (int)high_seq) >= 0) {
+			high_lkb = iter;
+			high_seq = iter->lkb_lvbseq;
 		}
 	}
 
-	list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
-		if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
+	list_for_each_entry(iter, &r->res_convertqueue, lkb_statequeue) {
+		if (!(iter->lkb_exflags & DLM_LKF_VALBLK))
 			continue;
 
 		lock_lvb_exists = 1;
 
-		if (lkb->lkb_grmode > DLM_LOCK_CR) {
-			big_lock_exists = 1;
+		if (iter->lkb_grmode > DLM_LOCK_CR) {
+			big_lkb = iter;
 			goto setflag;
 		}
 
-		if (((int)lkb->lkb_lvbseq - (int)high_seq) >= 0) {
-			high_lkb = lkb;
-			high_seq = lkb->lkb_lvbseq;
+		if (((int)iter->lkb_lvbseq - (int)high_seq) >= 0) {
+			high_lkb = iter;
+			high_seq = iter->lkb_lvbseq;
 		}
 	}
 
@@ -790,7 +789,7 @@ static void recover_lvb(struct dlm_rsb *r)
 		goto out;
 
 	/* lvb is invalidated if only NL/CR locks remain */
-	if (!big_lock_exists)
+	if (!big_lkb)
 		rsb_set_flag(r, RSB_VALNOTVALID);
 
 	if (!r->res_lvbptr) {
@@ -799,9 +798,9 @@ static void recover_lvb(struct dlm_rsb *r)
 			goto out;
 	}
 
-	if (big_lock_exists) {
-		r->res_lvbseq = lkb->lkb_lvbseq;
-		memcpy(r->res_lvbptr, lkb->lkb_lvbptr, lvblen);
+	if (big_lkb) {
+		r->res_lvbseq = big_lkb->lkb_lvbseq;
+		memcpy(r->res_lvbptr, big_lkb->lkb_lvbptr, lvblen);
 	} else if (high_lkb) {
 		r->res_lvbseq = high_lkb->lkb_lvbseq;
 		memcpy(r->res_lvbptr, high_lkb->lkb_lvbptr, lvblen);
-- 
2.31.1