[PATCHv2 dlm/next 01/12] dlm: introduce dlm_find_lockspace_name()

[Alexander Aring <aahringo@redhat.com>]

A DLM lockspace can be either identified by it's unique id or name. Later
patches will introduce a new netlink api that is using a unique
lockspace name to identify a lockspace in the lslist. This is mostly
required for sysfs functionality that is currently solved by a per
lockspace kobject allocation. The new netlink api cannot simple lookup
the lockspace by a container_of() call to do whatever sysfs is
providing so we introduce dlm_find_lockspace_name() to offer such
functionality.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lockspace.c | 18 ++++++++++++++++++
 fs/dlm/lockspace.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index 8afac6e2dff0..00d37125bc44 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -238,6 +238,24 @@ void dlm_lockspace_exit(void)
 	kset_unregister(dlm_kset);
 }
 
+struct dlm_ls *dlm_find_lockspace_name(const char *lsname)
+{
+	struct dlm_ls *ls;
+
+	spin_lock_bh(&lslist_lock);
+
+	list_for_each_entry(ls, &lslist, ls_list) {
+		if (!strncmp(ls->ls_name, lsname, DLM_LOCKSPACE_LEN)) {
+			atomic_inc(&ls->ls_count);
+			goto out;
+		}
+	}
+	ls = NULL;
+ out:
+	spin_unlock_bh(&lslist_lock);
+	return ls;
+}
+
 struct dlm_ls *dlm_find_lockspace_global(uint32_t id)
 {
 	struct dlm_ls *ls;
diff --git a/fs/dlm/lockspace.h b/fs/dlm/lockspace.h
index 47ebd4411926..7898a906aab9 100644
--- a/fs/dlm/lockspace.h
+++ b/fs/dlm/lockspace.h
@@ -22,6 +22,7 @@
 
 int dlm_lockspace_init(void);
 void dlm_lockspace_exit(void);
+struct dlm_ls *dlm_find_lockspace_name(const char *lsname);
 struct dlm_ls *dlm_find_lockspace_global(uint32_t id);
 struct dlm_ls *dlm_find_lockspace_local(void *id);
 struct dlm_ls *dlm_find_lockspace_device(int minor);
-- 
2.43.0