fs/lock: add helper locks_owner_has_blockers to check for blockers

Add helper locks_owner_has_blockers to check if there is any blockers
for a given lockowner.

Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>

diff --git a/fs/locks.c b/fs/locks.c
index 8c6df10cd9ed2e6300c03015a6e717b0c6dd999c..c369841ef7d190c7a5e499601d515a7f2974a5c7 100644 (file)
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
 }
 EXPORT_SYMBOL_GPL(locks_release_private);
 
+/**
+ * locks_owner_has_blockers - Check for blocking lock requests
+ * @flctx: file lock context
+ * @owner: lock owner
+ *
+ * Return values:
+ *   %true: @owner has at least one blocker
+ *   %false: @owner has no blockers
+ */
+bool locks_owner_has_blockers(struct file_lock_context *flctx,
+               fl_owner_t owner)
+{
+       struct file_lock *fl;
+
+       spin_lock(&flctx->flc_lock);
+       list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
+               if (fl->fl_owner != owner)
+                       continue;
+               if (!list_empty(&fl->fl_blocked_requests)) {
+                       spin_unlock(&flctx->flc_lock);
+                       return true;
+               }
+       }
+       spin_unlock(&flctx->flc_lock);
+       return false;
+}
+EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
+
 /* Free a lock which is not in use. */
 void locks_free_lock(struct file_lock *fl)
 {

diff --git a/include/linux/fs.h b/include/linux/fs.h
index bbde95387a23af8daf91f0926069a2090c35bd0f..b8ed7f974fb43fc5cc3c41e95991d65fdf55f315 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1174,6 +1174,8 @@ extern void lease_unregister_notifier(struct notifier_block *);
 struct files_struct;
 extern void show_fd_locks(struct seq_file *f,
                         struct file *filp, struct files_struct *files);
+extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
+                       fl_owner_t owner);
 #else /* !CONFIG_FILE_LOCKING */
 static inline int fcntl_getlk(struct file *file, unsigned int cmd,
                              struct flock __user *user)
@@ -1309,6 +1311,11 @@ static inline int lease_modify(struct file_lock *fl, int arg,
 struct files_struct;
 static inline void show_fd_locks(struct seq_file *f,
                        struct file *filp, struct files_struct *files) {}
+static inline bool locks_owner_has_blockers(struct file_lock_context *flctx,
+                       fl_owner_t owner)
+{
+       return false;
+}
 #endif /* !CONFIG_FILE_LOCKING */
 
 static inline struct inode *file_inode(const struct file *f)