1 files changed, 23 insertions, 1 deletions

diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
index 77d0df42fe02..ddf55dafba2d 100644
--- a/fs/ocfs2/dlm/dlmfs.c
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -43,6 +43,7 @@
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/backing-dev.h>
+#include <linux/poll.h>
 
 #include <asm/uaccess.h>
 
@@ -98,8 +99,12 @@ static const struct dlm_protocol_version user_locking_protocol = {
  * The ABI features are local to this machine's dlmfs mount.  This is
  * distinct from the locking protocol, which is concerned with inter-node
  * interaction.
+ *
+ * Capabilities:
+ * - bast       : POLLIN against the file descriptor of a held lock
+ *                signifies a bast fired on the lock.
  */
-#define DLMFS_CAPABILITIES ""
+#define DLMFS_CAPABILITIES "bast"
 extern int param_set_dlmfs_capabilities(const char *val,
                                         struct kernel_param *kp)
 {
@@ -215,6 +220,22 @@ static int dlmfs_file_release(struct inode *inode,
         return 0;
 }
 
+static unsigned int dlmfs_file_poll(struct file *file, poll_table *wait)
+{
+        int event = 0;
+        struct inode *inode = file->f_path.dentry->d_inode;
+        struct dlmfs_inode_private *ip = DLMFS_I(inode);
+
+        poll_wait(file, &ip->ip_lockres.l_event, wait);
+
+        spin_lock(&ip->ip_lockres.l_lock);
+        if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
+                event = POLLIN | POLLRDNORM;
+        spin_unlock(&ip->ip_lockres.l_lock);
+
+        return event;
+}
+
 static ssize_t dlmfs_file_read(struct file *filp,
                                char __user *buf,
                                size_t count,
@@ -585,6 +606,7 @@ static int dlmfs_fill_super(struct super_block * sb,
 static const struct file_operations dlmfs_file_operations = {
         .open           = dlmfs_file_open,
         .release        = dlmfs_file_release,
+        .poll           = dlmfs_file_poll,
         .read           = dlmfs_file_read,
         .write          = dlmfs_file_write,
 };