Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending

Pull SCSI target updates from Nicholas Bellinger:
 "Here are the target updates for v3.18-rc2 code.  These where
  originally destined for -rc1, but due to the combination of travel
  last week for KVM Forum and my mistake of taking the three week merge
  window literally, the pull request slipped..  Apologies for that.

  Things where reasonably quiet this round.  The highlights include:

   - New userspace backend driver (target_core_user.ko) by Shaohua Li
     and Andy Grover
   - A number of cleanups in target, iscsi-taret and qla_target code
     from Joern Engel
   - Fix an OOPs related to queue full handling with CHECK_CONDITION
     status from Quinn Tran
   - Fix to disable TX completion interrupt coalescing in iser-target,
     that was causing problems on some hardware
   - Fix for PR APTPL metadata handling with demo-mode ACLs

  I'm most excited about the new backend driver that uses UIO + shared
  memory ring to dispatch I/O and control commands into user-space.
  This was probably the most requested feature by users over the last
  couple of years, and opens up a new area of development + porting of
  existing user-space storage applications to LIO.  Thanks to Shaohua +
  Andy for making this happen.

  Also another honorable mention, a new Xen PV SCSI driver was merged
  via the xen/tip.git tree recently, which puts us now at 10 target
  drivers in upstream! Thanks to David Vrabel + Juergen Gross for their
  work to get this code merged"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (40 commits)
  target/file: fix inclusive vfs_fsync_range() end
  iser-target: Disable TX completion interrupt coalescing
  target: Add force_pr_aptpl device attribute
  target: Fix APTPL metadata handling for dynamic MappedLUNs
  qla_target: don't delete changed nacls
  target/user: Recalculate pad size inside is_ring_space_avail()
  tcm_loop: Fixup tag handling
  iser-target: Fix smatch warning
  target/user: Fix up smatch warnings in tcmu_netlink_event
  target: Add a user-passthrough backstore
  target: Add documentation on the target userspace pass-through driver
  uio: Export definition of struct uio_device
  target: Remove unneeded check in sbc_parse_cdb
  target: Fix queue full status NULL pointer for SCF_TRANSPORT_TASK_SENSE
  qla_target: rearrange struct qla_tgt_prm
  qla_target: improve qlt_unmap_sg()
  qla_target: make some global functions static
  qla_target: remove unused parameter
  target: simplify core_tmr_abort_task
  target: encapsulate smp_mb__after_atomic()
  ...

2 files changed, 143 insertions, 0 deletions

diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 6cad97485bad..b70237e8bc37 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -374,6 +374,7 @@ header-y += swab.h
 header-y += synclink.h
 header-y += sysctl.h
 header-y += sysinfo.h
+header-y += target_core_user.h
 header-y += taskstats.h
 header-y += tcp.h
 header-y += tcp_metrics.h
diff --git a/include/uapi/linux/target_core_user.h b/include/uapi/linux/target_core_user.h
new file mode 100644
index 000000000000..7dcfbe6771b1
--- /dev/null
+++ b/include/uapi/linux/target_core_user.h
@@ -0,0 +1,142 @@
+#ifndef __TARGET_CORE_USER_H
+#define __TARGET_CORE_USER_H
+
+/* This header will be used by application too */
+
+#include <linux/types.h>
+#include <linux/uio.h>
+
+#ifndef __packed
+#define __packed                        __attribute__((packed))
+#endif
+
+#define TCMU_VERSION "1.0"
+
+/*
+ * Ring Design
+ * -----------
+ *
+ * The mmaped area is divided into three parts:
+ * 1) The mailbox (struct tcmu_mailbox, below)
+ * 2) The command ring
+ * 3) Everything beyond the command ring (data)
+ *
+ * The mailbox tells userspace the offset of the command ring from the
+ * start of the shared memory region, and how big the command ring is.
+ *
+ * The kernel passes SCSI commands to userspace by putting a struct
+ * tcmu_cmd_entry in the ring, updating mailbox->cmd_head, and poking
+ * userspace via uio's interrupt mechanism.
+ *
+ * tcmu_cmd_entry contains a header. If the header type is PAD,
+ * userspace should skip hdr->length bytes (mod cmdr_size) to find the
+ * next cmd_entry.
+ *
+ * Otherwise, the entry will contain offsets into the mmaped area that
+ * contain the cdb and data buffers -- the latter accessible via the
+ * iov array. iov addresses are also offsets into the shared area.
+ *
+ * When userspace is completed handling the command, set
+ * entry->rsp.scsi_status, fill in rsp.sense_buffer if appropriate,
+ * and also set mailbox->cmd_tail equal to the old cmd_tail plus
+ * hdr->length, mod cmdr_size. If cmd_tail doesn't equal cmd_head, it
+ * should process the next packet the same way, and so on.
+ */
+
+#define TCMU_MAILBOX_VERSION 1
+#define ALIGN_SIZE 64 /* Should be enough for most CPUs */
+
+struct tcmu_mailbox {
+        __u16 version;
+        __u16 flags;
+        __u32 cmdr_off;
+        __u32 cmdr_size;
+
+        __u32 cmd_head;
+
+        /* Updated by user. On its own cacheline */
+        __u32 cmd_tail __attribute__((__aligned__(ALIGN_SIZE)));
+
+} __packed;
+
+enum tcmu_opcode {
+        TCMU_OP_PAD = 0,
+        TCMU_OP_CMD,
+};
+
+/*
+ * Only a few opcodes, and length is 8-byte aligned, so use low bits for opcode.
+ */
+struct tcmu_cmd_entry_hdr {
+                __u32 len_op;
+} __packed;
+
+#define TCMU_OP_MASK 0x7
+
+static inline enum tcmu_opcode tcmu_hdr_get_op(struct tcmu_cmd_entry_hdr *hdr)
+{
+        return hdr->len_op & TCMU_OP_MASK;
+}
+
+static inline void tcmu_hdr_set_op(struct tcmu_cmd_entry_hdr *hdr, enum tcmu_opcode op)
+{
+        hdr->len_op &= ~TCMU_OP_MASK;
+        hdr->len_op |= (op & TCMU_OP_MASK);
+}
+
+static inline __u32 tcmu_hdr_get_len(struct tcmu_cmd_entry_hdr *hdr)
+{
+        return hdr->len_op & ~TCMU_OP_MASK;
+}
+
+static inline void tcmu_hdr_set_len(struct tcmu_cmd_entry_hdr *hdr, __u32 len)
+{
+        hdr->len_op &= TCMU_OP_MASK;
+        hdr->len_op |= len;
+}
+
+/* Currently the same as SCSI_SENSE_BUFFERSIZE */
+#define TCMU_SENSE_BUFFERSIZE 96
+
+struct tcmu_cmd_entry {
+        struct tcmu_cmd_entry_hdr hdr;
+
+        uint16_t cmd_id;
+        uint16_t __pad1;
+
+        union {
+                struct {
+                        uint64_t cdb_off;
+                        uint64_t iov_cnt;
+                        struct iovec iov[0];
+                } req;
+                struct {
+                        uint8_t scsi_status;
+                        uint8_t __pad1;
+                        uint16_t __pad2;
+                        uint32_t __pad3;
+                        char sense_buffer[TCMU_SENSE_BUFFERSIZE];
+                } rsp;
+        };
+
+} __packed;
+
+#define TCMU_OP_ALIGN_SIZE sizeof(uint64_t)
+
+enum tcmu_genl_cmd {
+        TCMU_CMD_UNSPEC,
+        TCMU_CMD_ADDED_DEVICE,
+        TCMU_CMD_REMOVED_DEVICE,
+        __TCMU_CMD_MAX,
+};
+#define TCMU_CMD_MAX (__TCMU_CMD_MAX - 1)
+
+enum tcmu_genl_attr {
+        TCMU_ATTR_UNSPEC,
+        TCMU_ATTR_DEVICE,
+        TCMU_ATTR_MINOR,
+        __TCMU_ATTR_MAX,
+};
+#define TCMU_ATTR_MAX (__TCMU_ATTR_MAX - 1)
+
+#endif