diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index fa5e3bdc295..3867244fb14 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -68,6 +68,7 @@ struct ocfs2_mask_waiter {
 
 static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres);
 static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres);
+static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres);
 
 /*
  * Return value from ->downconvert_worker functions.
@@ -252,6 +253,11 @@ static struct ocfs2_lock_res_ops ocfs2_inode_open_lops = {
 	.flags		= 0,
 };
 
+static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
+	.get_osb	= ocfs2_get_file_osb,
+	.flags		= 0,
+};
+
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
 	return lockres->l_type == OCFS2_LOCK_TYPE_META ||
@@ -310,6 +316,17 @@ static int ocfs2_inode_lock_update(struct inode *inode,
 				  struct buffer_head **bh);
 static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
 static inline int ocfs2_highest_compat_lock_level(int level);
+static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+				      int new_level);
+static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
+				  struct ocfs2_lock_res *lockres,
+				  int new_level,
+				  int lvb);
+static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
+				        struct ocfs2_lock_res *lockres);
+static int ocfs2_cancel_convert(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres);
+
 
 static void ocfs2_build_lock_name(enum ocfs2_lock_type type,
 				  u64 blkno,
@@ -419,6 +436,13 @@ static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres)
 	return OCFS2_SB(inode->i_sb);
 }
 
+static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_file_private *fp = lockres->l_priv;
+
+	return OCFS2_SB(fp->fp_file->f_mapping->host->i_sb);
+}
+
 static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres)
 {
 	__be64 inode_blkno_be;
@@ -499,6 +523,21 @@ static void ocfs2_rename_lock_res_init(struct ocfs2_lock_res *res,
 				   &ocfs2_rename_lops, osb);
 }
 
+void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
+			      struct ocfs2_file_private *fp)
+{
+	struct inode *inode = fp->fp_file->f_mapping->host;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+
+	ocfs2_lock_res_init_once(lockres);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_FLOCK, oi->ip_blkno,
+			      inode->i_generation, lockres->l_name);
+	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
+				   OCFS2_LOCK_TYPE_FLOCK, &ocfs2_flock_lops,
+				   fp);
+	lockres->l_flags |= OCFS2_LOCK_NOCACHE;
+}
+
 void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
 {
 	mlog_entry_void();
@@ -715,6 +754,13 @@ static void ocfs2_blocking_ast(void *opaque, int level)
 	     lockres->l_name, level, lockres->l_level,
 	     ocfs2_lock_type_string(lockres->l_type));
 
+	/*
+	 * We can skip the bast for locks which don't enable caching -
+	 * they'll be dropped at the earliest possible time anyway.
+	 */
+	if (lockres->l_flags & OCFS2_LOCK_NOCACHE)
+		return;
+
 	spin_lock_irqsave(&lockres->l_lock, flags);
 	needs_downconvert = ocfs2_generic_handle_bast(lockres, level);
 	if (needs_downconvert)
@@ -926,6 +972,21 @@ static int lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
 
 }
 
+static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
+					     struct ocfs2_lock_res *lockres)
+{
+	int ret;
+
+	ret = wait_for_completion_interruptible(&mw->mw_complete);
+	if (ret)
+		lockres_remove_mask_waiter(lockres, mw);
+	else
+		ret = mw->mw_status;
+	/* Re-arm the completion in case we want to wait on it again */
+	INIT_COMPLETION(mw->mw_complete);
+	return ret;
+}
+
 static int ocfs2_cluster_lock(struct ocfs2_super *osb,
 			      struct ocfs2_lock_res *lockres,
 			      int level,
@@ -1296,6 +1357,212 @@ out:
 	mlog_exit_void();
 }
 
+static int ocfs2_flock_handle_signal(struct ocfs2_lock_res *lockres,
+				     int level)
+{
+	int ret;
+	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
+	unsigned long flags;
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+retry_cancel:
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
+		ret = ocfs2_prepare_cancel_convert(osb, lockres);
+		if (ret) {
+			spin_unlock_irqrestore(&lockres->l_lock, flags);
+			ret = ocfs2_cancel_convert(osb, lockres);
+			if (ret < 0) {
+				mlog_errno(ret);
+				goto out;
+			}
+			goto retry_cancel;
+		}
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		ocfs2_wait_for_mask(&mw);
+		goto retry_cancel;
+	}
+
+	ret = -ERESTARTSYS;
+	/*
+	 * We may still have gotten the lock, in which case there's no
+	 * point to restarting the syscall.
+	 */
+	if (lockres->l_level == level)
+		ret = 0;
+
+	mlog(0, "Cancel returning %d. flags: 0x%lx, level: %d, act: %d\n", ret,
+	     lockres->l_flags, lockres->l_level, lockres->l_action);
+
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+out:
+	return ret;
+}
+
+/*
+ * ocfs2_file_lock() and ocfs2_file_unlock() map to a single pair of
+ * flock() calls. The locking approach this requires is sufficiently
+ * different from all other cluster lock types that we implement a
+ * seperate path to the "low-level" dlm calls. In particular:
+ *
+ * - No optimization of lock levels is done - we take at exactly
+ *   what's been requested.
+ *
+ * - No lock caching is employed. We immediately downconvert to
+ *   no-lock at unlock time. This also means flock locks never go on
+ *   the blocking list).
+ *
+ * - Since userspace can trivially deadlock itself with flock, we make
+ *   sure to allow cancellation of a misbehaving applications flock()
+ *   request.
+ *
+ * - Access to any flock lockres doesn't require concurrency, so we
+ *   can simplify the code by requiring the caller to guarantee
+ *   serialization of dlmglue flock calls.
+ */
+int ocfs2_file_lock(struct file *file, int ex, int trylock)
+{
+	int ret, level = ex ? LKM_EXMODE : LKM_PRMODE;
+	unsigned int lkm_flags = trylock ? LKM_NOQUEUE : 0;
+	unsigned long flags;
+	struct ocfs2_file_private *fp = file->private_data;
+	struct ocfs2_lock_res *lockres = &fp->fp_flock;
+	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+	if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||
+	    (lockres->l_level > LKM_NLMODE)) {
+		mlog(ML_ERROR,
+		     "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
+		     "level: %u\n", lockres->l_name, lockres->l_flags,
+		     lockres->l_level);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		/*
+		 * Get the lock at NLMODE to start - that way we
+		 * can cancel the upconvert request if need be.
+		 */
+		ret = ocfs2_lock_create(osb, lockres, LKM_NLMODE, 0);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		ret = ocfs2_wait_for_mask(&mw);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+		spin_lock_irqsave(&lockres->l_lock, flags);
+	}
+
+	lockres->l_action = OCFS2_AST_CONVERT;
+	lkm_flags |= LKM_CONVERT;
+	lockres->l_requested = level;
+	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+
+	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ret = dlmlock(osb->dlm, level, &lockres->l_lksb, lkm_flags,
+		      lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1,
+		      ocfs2_locking_ast, lockres, ocfs2_blocking_ast);
+	if (ret != DLM_NORMAL) {
+		if (trylock && ret == DLM_NOTQUEUED)
+			ret = -EAGAIN;
+		else {
+			ocfs2_log_dlm_error("dlmlock", ret, lockres);
+			ret = -EINVAL;
+		}
+
+		ocfs2_recover_from_dlm_error(lockres, 1);
+		lockres_remove_mask_waiter(lockres, &mw);
+		goto out;
+	}
+
+	ret = ocfs2_wait_for_mask_interruptible(&mw, lockres);
+	if (ret == -ERESTARTSYS) {
+		/*
+		 * Userspace can cause deadlock itself with
+		 * flock(). Current behavior locally is to allow the
+		 * deadlock, but abort the system call if a signal is
+		 * received. We follow this example, otherwise a
+		 * poorly written program could sit in kernel until
+		 * reboot.
+		 *
+		 * Handling this is a bit more complicated for Ocfs2
+		 * though. We can't exit this function with an
+		 * outstanding lock request, so a cancel convert is
+		 * required. We intentionally overwrite 'ret' - if the
+		 * cancel fails and the lock was granted, it's easier
+		 * to just bubble sucess back up to the user.
+		 */
+		ret = ocfs2_flock_handle_signal(lockres, level);
+	}
+
+out:
+
+	mlog(0, "Lock: \"%s\" ex: %d, trylock: %d, returns: %d\n",
+	     lockres->l_name, ex, trylock, ret);
+	return ret;
+}
+
+void ocfs2_file_unlock(struct file *file)
+{
+	int ret;
+	unsigned long flags;
+	struct ocfs2_file_private *fp = file->private_data;
+	struct ocfs2_lock_res *lockres = &fp->fp_flock;
+	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED))
+		return;
+
+	if (lockres->l_level == LKM_NLMODE)
+		return;
+
+	mlog(0, "Unlock: \"%s\" flags: 0x%lx, level: %d, act: %d\n",
+	     lockres->l_name, lockres->l_flags, lockres->l_level,
+	     lockres->l_action);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	/*
+	 * Fake a blocking ast for the downconvert code.
+	 */
+	lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
+	lockres->l_blocking = LKM_EXMODE;
+
+	ocfs2_prepare_downconvert(lockres, LKM_NLMODE);
+	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0);
+	if (ret) {
+		mlog_errno(ret);
+		return;
+	}
+
+	ret = ocfs2_wait_for_mask(&mw);
+	if (ret)
+		mlog_errno(ret);
+}
+
 static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
 					struct ocfs2_lock_res *lockres)
 {
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index 6dcbc944e8c..5f17243ba50 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -66,6 +66,9 @@ void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
 			       struct inode *inode);
 void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
 				u64 parent, struct inode *inode);
+struct ocfs2_file_private;
+void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
+			      struct ocfs2_file_private *fp);
 void ocfs2_lock_res_free(struct ocfs2_lock_res *res);
 int ocfs2_create_new_inode_locks(struct inode *inode);
 int ocfs2_drop_inode_locks(struct inode *inode);
@@ -98,6 +101,8 @@ int ocfs2_rename_lock(struct ocfs2_super *osb);
 void ocfs2_rename_unlock(struct ocfs2_super *osb);
 int ocfs2_dentry_lock(struct dentry *dentry, int ex);
 void ocfs2_dentry_unlock(struct dentry *dentry, int ex);
+int ocfs2_file_lock(struct file *file, int ex, int trylock);
+void ocfs2_file_unlock(struct file *file);
 
 void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres);
 void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
diff --git a/fs/ocfs2/file.h b/fs/ocfs2/file.h
index 066f14add3a..048ddcaf5c8 100644
--- a/fs/ocfs2/file.h
+++ b/fs/ocfs2/file.h
@@ -32,6 +32,12 @@ extern const struct inode_operations ocfs2_file_iops;
 extern const struct inode_operations ocfs2_special_file_iops;
 struct ocfs2_alloc_context;
 
+struct ocfs2_file_private {
+	struct file		*fp_file;
+	struct mutex		fp_mutex;
+	struct ocfs2_lock_res	fp_flock;
+};
+
 enum ocfs2_alloc_restarted {
 	RESTART_NONE = 0,
 	RESTART_TRANS,
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index d12bd7036da..63c131e1cc7 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -101,6 +101,7 @@ enum ocfs2_unlock_action {
 					       * about to be
 					       * dropped. */
 #define OCFS2_LOCK_QUEUED        (0x00000100) /* queued for downconvert */
+#define OCFS2_LOCK_NOCACHE       (0x00000200) /* don't use a holder count */
 
 struct ocfs2_lock_res_ops;
 
diff --git a/fs/ocfs2/ocfs2_lockid.h b/fs/ocfs2/ocfs2_lockid.h
index 4ca02b1c38a..86f3e3799c2 100644
--- a/fs/ocfs2/ocfs2_lockid.h
+++ b/fs/ocfs2/ocfs2_lockid.h
@@ -45,6 +45,7 @@ enum ocfs2_lock_type {
 	OCFS2_LOCK_TYPE_RW,
 	OCFS2_LOCK_TYPE_DENTRY,
 	OCFS2_LOCK_TYPE_OPEN,
+	OCFS2_LOCK_TYPE_FLOCK,
 	OCFS2_NUM_LOCK_TYPES
 };
 
@@ -73,6 +74,9 @@ static inline char ocfs2_lock_type_char(enum ocfs2_lock_type type)
 		case OCFS2_LOCK_TYPE_OPEN:
 			c = 'O';
 			break;
+		case OCFS2_LOCK_TYPE_FLOCK:
+			c = 'F';
+			break;
 		default:
 			c = '\0';
 	}
@@ -90,6 +94,7 @@ static char *ocfs2_lock_type_strings[] = {
 	[OCFS2_LOCK_TYPE_RW] = "Write/Read",
 	[OCFS2_LOCK_TYPE_DENTRY] = "Dentry",
 	[OCFS2_LOCK_TYPE_OPEN] = "Open",
+	[OCFS2_LOCK_TYPE_FLOCK] = "Flock",
 };
 
 static inline const char *ocfs2_lock_type_string(enum ocfs2_lock_type type)