[PATCH 1/3] ocfs2: add ocfs2_try_rw_lock and ocfs2_try_inode_lock

[Gang He <ghe@suse.com>]

Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
will be used in non-block IO scenarios.

Signed-off-by: Gang He <ghe@suse.com>
---
 fs/ocfs2/dlmglue.c | 22 ++++++++++++++++++++++
 fs/ocfs2/dlmglue.h |  4 ++++
 2 files changed, 26 insertions(+)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 4689940..5cfbd04 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -1742,6 +1742,28 @@ int ocfs2_rw_lock(struct inode *inode, int write)
 	return status;
 }
 
+int ocfs2_try_rw_lock(struct inode *inode, int write)
+{
+	int status, level;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu try to take %s RW lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	lockres = &OCFS2_I(inode)->ip_rw_lockres;
+
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level,
+				    DLM_LKF_NOQUEUE, 0);
+	return status;
+}
+
 void ocfs2_rw_unlock(struct inode *inode, int write)
 {
 	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index a7fc18b..05910fc 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
 int ocfs2_create_new_inode_locks(struct inode *inode);
 int ocfs2_drop_inode_locks(struct inode *inode);
 int ocfs2_rw_lock(struct inode *inode, int write);
+int ocfs2_try_rw_lock(struct inode *inode, int write);
 void ocfs2_rw_unlock(struct inode *inode, int write);
 int ocfs2_open_lock(struct inode *inode);
 int ocfs2_try_open_lock(struct inode *inode, int write);
@@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
 /* 99% of the time we don't want to supply any additional flags --
  * those are for very specific cases only. */
 #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
+#define ocfs2_try_inode_lock(i, b, e)\
+		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
+		OI_LS_NORMAL)
 void ocfs2_inode_unlock(struct inode *inode,
 		       int ex);
 int ocfs2_super_lock(struct ocfs2_super *osb,
-- 
1.8.5.6