Merge branch 'for-4.4/reservations' of git://git.kernel.dk/linux-block

Pull block reservation support from Jens Axboe:
 "This adds support for persistent reservations, both at the core level,
  as well as for sd and NVMe"

[ Background from the docs: "Persistent Reservations allow restricting
  access to block devices to specific initiators in a shared storage
  setup.  All implementations are expected to ensure the reservations
  survive a power loss and cover all connections in a multi path
  environment" ]

* 'for-4.4/reservations' of git://git.kernel.dk/linux-block:
  NVMe: Precedence error in nvme_pr_clear()
  nvme: add missing endianess annotations in nvme_pr_command
  NVMe: Add persistent reservation ops
  sd: implement the Persistent Reservation API
  block: add an API for Persistent Reservations
  block: cleanup blkdev_ioctl

include/uapi/linux/pr.h

@@ -0,0 +1,48 @@
+#ifndef _UAPI_PR_H
+#define _UAPI_PR_H
+
+enum pr_type {
+	PR_WRITE_EXCLUSIVE		= 1,
+	PR_EXCLUSIVE_ACCESS		= 2,
+	PR_WRITE_EXCLUSIVE_REG_ONLY	= 3,
+	PR_EXCLUSIVE_ACCESS_REG_ONLY	= 4,
+	PR_WRITE_EXCLUSIVE_ALL_REGS	= 5,
+	PR_EXCLUSIVE_ACCESS_ALL_REGS	= 6,
+};
+
+struct pr_reservation {
+	__u64	key;
+	__u32	type;
+	__u32	flags;
+};
+
+struct pr_registration {
+	__u64	old_key;
+	__u64	new_key;
+	__u32	flags;
+	__u32	__pad;
+};
+
+struct pr_preempt {
+	__u64	old_key;
+	__u64	new_key;
+	__u32	type;
+	__u32	flags;
+};
+
+struct pr_clear {
+	__u64	key;
+	__u32	flags;
+	__u32	__pad;
+};
+
+#define PR_FL_IGNORE_KEY	(1 << 0)	/* ignore existing key */
+
+#define IOC_PR_REGISTER		_IOW('p', 200, struct pr_registration)
+#define IOC_PR_RESERVE		_IOW('p', 201, struct pr_reservation)
+#define IOC_PR_RELEASE		_IOW('p', 202, struct pr_reservation)
+#define IOC_PR_PREEMPT		_IOW('p', 203, struct pr_preempt)
+#define IOC_PR_PREEMPT_ABORT	_IOW('p', 204, struct pr_preempt)
+#define IOC_PR_CLEAR		_IOW('p', 205, struct pr_clear)
+
+#endif /* _UAPI_PR_H */