staging: lustre: ldlm: reclaim granted locks defensively

It was discovered that to many ldlm locks where being
created on the server side to the point of memory
exhaustion. The work of LU-6529 introduced watermarks
to avoid this memory exhaustion. This is the client
side part of this work for the upstream client.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6529
Reviewed-on: http://review.whamcloud.com/14931
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6929
Reviewed-on: http://review.whamcloud.com/15813
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/staging/lustre/lnet/libcfs/hash.c b/drivers/staging/lustre/lnet/libcfs/hash.c
index 23283b6e09ab..997b8a5ed8ff 100644
--- a/drivers/staging/lustre/lnet/libcfs/hash.c
+++ b/drivers/staging/lustre/lnet/libcfs/hash.c
@@ -1552,7 +1552,7 @@ EXPORT_SYMBOL(cfs_hash_size_get);
  */
 static int
 cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
-			void *data)
+			void *data, int start)
 {
 	struct hlist_node *hnode;
 	struct hlist_node *tmp;
@@ -1560,18 +1560,25 @@ cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
 	__u32 version;
 	int count = 0;
 	int stop_on_change;
-	int rc;
+	int end = -1;
+	int rc = 0;
 	int i;
 
 	stop_on_change = cfs_hash_with_rehash_key(hs) ||
 			 !cfs_hash_with_no_itemref(hs) ||
 			 !hs->hs_ops->hs_put_locked;
 	cfs_hash_lock(hs, 0);
+again:
 	LASSERT(!cfs_hash_is_rehashing(hs));
 
 	cfs_hash_for_each_bucket(hs, &bd, i) {
 		struct hlist_head *hhead;
 
+		if (i < start)
+			continue;
+		else if (end > 0 && i >= end)
+			break;
+
 		cfs_hash_bd_lock(hs, &bd, 0);
 		version = cfs_hash_bd_version_get(&bd);
 
@@ -1611,14 +1618,19 @@ cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
 		if (rc) /* callback wants to break iteration */
 			break;
 	}
-	cfs_hash_unlock(hs, 0);
+	if (start > 0 && !rc) {
+		end = start;
+		start = 0;
+		goto again;
+	}
 
+	cfs_hash_unlock(hs, 0);
 	return count;
 }
 
 int
 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
-			 void *data)
+			 void *data, int start)
 {
 	if (cfs_hash_with_no_lock(hs) ||
 	    cfs_hash_with_rehash_key(hs) ||
@@ -1630,7 +1642,7 @@ cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
 		return -EOPNOTSUPP;
 
 	cfs_hash_for_each_enter(hs);
-	cfs_hash_for_each_relax(hs, func, data);
+	cfs_hash_for_each_relax(hs, func, data, start);
 	cfs_hash_for_each_exit(hs);
 
 	return 0;
@@ -1662,7 +1674,7 @@ cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
 		return -EOPNOTSUPP;
 
 	cfs_hash_for_each_enter(hs);
-	while (cfs_hash_for_each_relax(hs, func, data)) {
+	while (cfs_hash_for_each_relax(hs, func, data, 0)) {
 		CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
 		       hs->hs_name, i++);
 	}