Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1137 insertions, 0 deletions

diff --git a/src/include/ceph_fs.h b/src/include/ceph_fs.h
new file mode 100644
index 000000000..28440c820
--- /dev/null
+++ b/src/include/ceph_fs.h
@@ -0,0 +1,1137 @@
+/*
+ * ceph_fs.h - Ceph constants and data types to share between kernel and
+ * user space.
+ *
+ * Most types in this file are defined as little-endian, and are
+ * primarily intended to describe data structures that pass over the
+ * wire or that are stored on disk.
+ *
+ * LGPL-2.1 or LGPL-3.0
+ */
+
+#ifndef CEPH_FS_H
+#define CEPH_FS_H
+
+#include "msgr.h"
+#include "rados.h"
+#include "include/encoding.h"
+#include "include/denc.h"
+
+/*
+ * The data structures defined here are shared between Linux kernel and
+ * user space.  Also, those data structures are maintained always in
+ * little-endian byte order, even on big-endian systems.  This is handled
+ * differently in kernel vs. user space.  For use as kernel headers, the
+ * little-endian fields need to use the __le16/__le32/__le64 types.  These
+ * are markers that indicate endian conversion routines must be used
+ * whenever such fields are accessed, which can be verified by checker
+ * tools like "sparse".  For use as user-space headers, the little-endian
+ * fields instead use types ceph_le16/ceph_le32/ceph_le64, which are C++
+ * classes that implement automatic endian conversion on every access.
+ * To still allow for header sharing, this file uses the __le types, but
+ * redefines those to the ceph_ types when compiled in user space.
+ */
+#ifndef __KERNEL__
+#include "byteorder.h"
+#define __le16 ceph_le16
+#define __le32 ceph_le32
+#define __le64 ceph_le64
+#endif
+
+/*
+ * subprotocol versions.  when specific messages types or high-level
+ * protocols change, bump the affected components.  we keep rev
+ * internal cluster protocols separately from the public,
+ * client-facing protocol.
+ */
+#define CEPH_OSDC_PROTOCOL   24 /* server/client */
+#define CEPH_MDSC_PROTOCOL   32 /* server/client */
+#define CEPH_MONC_PROTOCOL   15 /* server/client */
+
+
+#define CEPH_INO_ROOT             1
+/*
+ * hidden .ceph dir, which is no longer created but
+ * recognised in existing filesystems so that we
+ * don't try to fragment it.
+ */
+#define CEPH_INO_CEPH             2
+#define CEPH_INO_GLOBAL_SNAPREALM 3
+#define CEPH_INO_LOST_AND_FOUND   4 /* reserved ino for use in recovery */
+
+/* arbitrary limit on max # of monitors (cluster of 3 is typical) */
+#define CEPH_MAX_MON   31
+
+/*
+ * ceph_file_layout - describe data layout for a file/inode
+ */
+struct ceph_file_layout {
+	/* file -> object mapping */
+	__le32 fl_stripe_unit;     /* stripe unit, in bytes.  must be multiple
+				      of page size. */
+	__le32 fl_stripe_count;    /* over this many objects */
+	__le32 fl_object_size;     /* until objects are this big, then move to
+				      new objects */
+	__le32 fl_cas_hash;        /* UNUSED.  0 = none; 1 = sha256 */
+
+	/* pg -> disk layout */
+	__le32 fl_object_stripe_unit;  /* UNUSED.  for per-object parity, if any */
+
+	/* object -> pg layout */
+	__le32 fl_unused;       /* unused; used to be preferred primary for pg (-1 for none) */
+	__le32 fl_pg_pool;      /* namespace, crush rule, rep level */
+} __attribute__ ((packed));
+
+#define CEPH_MIN_STRIPE_UNIT 65536
+
+struct ceph_dir_layout {
+	__u8   dl_dir_hash;   /* see ceph_hash.h for ids */
+	__u8   dl_unused1;
+	__u16  dl_unused2;
+	__u32  dl_unused3;
+} __attribute__ ((packed));
+
+/* crypto algorithms */
+#define CEPH_CRYPTO_NONE 0x0
+#define CEPH_CRYPTO_AES  0x1
+
+#define CEPH_AES_IV "cephsageyudagreg"
+
+/* security/authentication protocols */
+#define CEPH_AUTH_UNKNOWN	0x0
+#define CEPH_AUTH_NONE	 	0x1
+#define CEPH_AUTH_CEPHX	 	0x2
+
+/* msgr2 protocol modes */
+#define CEPH_CON_MODE_UNKNOWN 0x0
+#define CEPH_CON_MODE_CRC     0x1
+#define CEPH_CON_MODE_SECURE  0x2
+
+extern const char *ceph_con_mode_name(int con_mode);
+
+/*  For options with "_", like: GSS_GSS
+    which means: Mode/Protocol to validate "authentication_authorization",
+    where:
+      - Authentication: Verifying the identity of an entity.
+      - Authorization:  Verifying that an authenticated entity has
+                        the right to access a particular resource.
+*/ 
+#define CEPH_AUTH_GSS     0x4
+#define CEPH_AUTH_GSS_GSS CEPH_AUTH_GSS
+
+#define CEPH_AUTH_UID_DEFAULT ((__u64) -1)
+
+
+/*********************************************
+ * message layer
+ */
+
+/*
+ * message types
+ */
+
+/* misc */
+#define CEPH_MSG_SHUTDOWN               1
+#define CEPH_MSG_PING                   2
+
+/* client <-> monitor */
+#define CEPH_MSG_MON_MAP                4
+#define CEPH_MSG_MON_GET_MAP            5
+#define CEPH_MSG_MON_GET_OSDMAP         6
+#define CEPH_MSG_MON_METADATA           7
+#define CEPH_MSG_STATFS                 13
+#define CEPH_MSG_STATFS_REPLY           14
+#define CEPH_MSG_MON_SUBSCRIBE          15
+#define CEPH_MSG_MON_SUBSCRIBE_ACK      16
+#define CEPH_MSG_AUTH			17
+#define CEPH_MSG_AUTH_REPLY		18
+#define CEPH_MSG_MON_GET_VERSION        19
+#define CEPH_MSG_MON_GET_VERSION_REPLY  20
+
+/* client <-> mds */
+#define CEPH_MSG_MDS_MAP                21
+
+#define CEPH_MSG_CLIENT_SESSION         22
+#define CEPH_MSG_CLIENT_RECONNECT       23
+
+#define CEPH_MSG_CLIENT_REQUEST         24
+#define CEPH_MSG_CLIENT_REQUEST_FORWARD 25
+#define CEPH_MSG_CLIENT_REPLY           26
+#define CEPH_MSG_CLIENT_RECLAIM		27
+#define CEPH_MSG_CLIENT_RECLAIM_REPLY   28
+#define CEPH_MSG_CLIENT_METRICS         29
+#define CEPH_MSG_CLIENT_CAPS            0x310
+#define CEPH_MSG_CLIENT_LEASE           0x311
+#define CEPH_MSG_CLIENT_SNAP            0x312
+#define CEPH_MSG_CLIENT_CAPRELEASE      0x313
+#define CEPH_MSG_CLIENT_QUOTA           0x314
+
+/* pool ops */
+#define CEPH_MSG_POOLOP_REPLY           48
+#define CEPH_MSG_POOLOP                 49
+
+
+/* osd */
+#define CEPH_MSG_OSD_MAP                41
+#define CEPH_MSG_OSD_OP                 42
+#define CEPH_MSG_OSD_OPREPLY            43
+#define CEPH_MSG_WATCH_NOTIFY           44
+#define CEPH_MSG_OSD_BACKOFF            61
+
+/* FSMap subscribers (see all MDS clusters at once) */
+#define CEPH_MSG_FS_MAP                 45
+/* FSMapUser subscribers (get MDS clusters name->ID mapping) */
+#define CEPH_MSG_FS_MAP_USER		103
+
+/* watch-notify operations */
+enum {
+	CEPH_WATCH_EVENT_NOTIFY		  = 1, /* notifying watcher */
+	CEPH_WATCH_EVENT_NOTIFY_COMPLETE  = 2, /* notifier notified when done */
+	CEPH_WATCH_EVENT_DISCONNECT       = 3, /* we were disconnected */
+};
+
+const char *ceph_watch_event_name(int o);
+
+/* pool operations */
+enum {
+  POOL_OP_CREATE			= 0x01,
+  POOL_OP_DELETE			= 0x02,
+  POOL_OP_AUID_CHANGE			= 0x03,
+  POOL_OP_CREATE_SNAP			= 0x11,
+  POOL_OP_DELETE_SNAP			= 0x12,
+  POOL_OP_CREATE_UNMANAGED_SNAP		= 0x21,
+  POOL_OP_DELETE_UNMANAGED_SNAP		= 0x22,
+};
+
+struct ceph_mon_request_header {
+	__le64 have_version;
+	__le16 session_mon;
+	__le64 session_mon_tid;
+} __attribute__ ((packed));
+
+struct ceph_mon_statfs {
+	struct ceph_mon_request_header monhdr;
+	struct ceph_fsid fsid;
+} __attribute__ ((packed));
+
+struct ceph_statfs {
+	__le64 kb, kb_used, kb_avail;
+	__le64 num_objects;
+} __attribute__ ((packed));
+
+struct ceph_mon_statfs_reply {
+	struct ceph_fsid fsid;
+	__le64 version;
+	struct ceph_statfs st;
+} __attribute__ ((packed));
+
+const char *ceph_pool_op_name(int op);
+
+struct ceph_mon_poolop {
+	struct ceph_mon_request_header monhdr;
+	struct ceph_fsid fsid;
+	__le32 pool;
+	__le32 op;
+	__le64 __old_auid;  // obsolete
+	__le64 snapid;
+	__le32 name_len;
+} __attribute__ ((packed));
+
+struct ceph_mon_poolop_reply {
+	struct ceph_mon_request_header monhdr;
+	struct ceph_fsid fsid;
+	__le32 reply_code;
+	__le32 epoch;
+	char has_data;
+	char data[0];
+} __attribute__ ((packed));
+
+struct ceph_mon_unmanaged_snap {
+	__le64 snapid;
+} __attribute__ ((packed));
+
+struct ceph_osd_getmap {
+	struct ceph_mon_request_header monhdr;
+	struct ceph_fsid fsid;
+	__le32 start;
+} __attribute__ ((packed));
+
+struct ceph_mds_getmap {
+	struct ceph_mon_request_header monhdr;
+	struct ceph_fsid fsid;
+} __attribute__ ((packed));
+
+struct ceph_client_mount {
+	struct ceph_mon_request_header monhdr;
+} __attribute__ ((packed));
+
+#define CEPH_SUBSCRIBE_ONETIME    1  /* i want only 1 update after have */
+
+struct ceph_mon_subscribe_item {
+	__le64 start;
+	__u8 flags;
+} __attribute__ ((packed));
+
+struct ceph_mon_subscribe_ack {
+	__le32 duration;         /* seconds */
+	struct ceph_fsid fsid;
+} __attribute__ ((packed));
+
+/*
+ * mdsmap flags
+ */
+#define CEPH_MDSMAP_NOT_JOINABLE                 (1<<0)  /* standbys cannot join */
+#define CEPH_MDSMAP_DOWN                         (CEPH_MDSMAP_NOT_JOINABLE) /* backwards compat */
+#define CEPH_MDSMAP_ALLOW_SNAPS                  (1<<1)  /* cluster allowed to create snapshots */
+/* deprecated #define CEPH_MDSMAP_ALLOW_MULTIMDS (1<<2) cluster allowed to have >1 active MDS */
+/* deprecated #define CEPH_MDSMAP_ALLOW_DIRFRAGS (1<<3) cluster allowed to fragment directories */
+#define CEPH_MDSMAP_ALLOW_MULTIMDS_SNAPS	     (1<<4)  /* cluster alllowed to enable MULTIMDS
+                                                            and SNAPS at the same time */
+#define CEPH_MDSMAP_ALLOW_STANDBY_REPLAY         (1<<5)  /* cluster alllowed to enable MULTIMDS */
+#define CEPH_MDSMAP_REFUSE_CLIENT_SESSION        (1<<6)  /* cluster allowed to refuse client session
+                                                            request */
+#define CEPH_MDSMAP_DEFAULTS (CEPH_MDSMAP_ALLOW_SNAPS | \
+			      CEPH_MDSMAP_ALLOW_MULTIMDS_SNAPS)
+
+/*
+ * mds states
+ *   > 0 -> in
+ *  <= 0 -> out
+ */
+#define CEPH_MDS_STATE_DNE          0  /* down, does not exist. */
+#define CEPH_MDS_STATE_STOPPED     -1  /* down, once existed, but no subtrees.
+					  empty log. */
+#define CEPH_MDS_STATE_BOOT        -4  /* up, boot announcement. */
+#define CEPH_MDS_STATE_STANDBY     -5  /* up, idle.  waiting for assignment. */
+#define CEPH_MDS_STATE_CREATING    -6  /* up, creating MDS instance. */
+#define CEPH_MDS_STATE_STARTING    -7  /* up, starting previously stopped mds */
+#define CEPH_MDS_STATE_STANDBY_REPLAY -8 /* up, tailing active node's journal */
+#define CEPH_MDS_STATE_REPLAYONCE   -9 /* Legacy, unused */
+#define CEPH_MDS_STATE_NULL         -10
+
+#define CEPH_MDS_STATE_REPLAY       8  /* up, replaying journal. */
+#define CEPH_MDS_STATE_RESOLVE      9  /* up, disambiguating distributed
+					  operations (import, rename, etc.) */
+#define CEPH_MDS_STATE_RECONNECT    10 /* up, reconnect to clients */
+#define CEPH_MDS_STATE_REJOIN       11 /* up, rejoining distributed cache */
+#define CEPH_MDS_STATE_CLIENTREPLAY 12 /* up, replaying client operations */
+#define CEPH_MDS_STATE_ACTIVE       13 /* up, active */
+#define CEPH_MDS_STATE_STOPPING     14 /* up, but exporting metadata */
+#define CEPH_MDS_STATE_DAMAGED      15 /* rank not replayable, need repair */
+
+extern const char *ceph_mds_state_name(int s);
+
+
+/*
+ * metadata lock types.
+ *  - these are bitmasks.. we can compose them
+ *  - they also define the lock ordering by the MDS
+ *  - a few of these are internal to the mds
+ */
+#define CEPH_LOCK_DN          (1 << 0)
+#define CEPH_LOCK_DVERSION    (1 << 1)
+#define CEPH_LOCK_ISNAP       (1 << 4)  /* snapshot lock. MDS internal */
+#define CEPH_LOCK_IPOLICY     (1 << 5)  /* policy lock on dirs. MDS internal */
+#define CEPH_LOCK_IFILE       (1 << 6)
+#define CEPH_LOCK_INEST       (1 << 7)  /* mds internal */
+#define CEPH_LOCK_IDFT        (1 << 8)  /* dir frag tree */
+#define CEPH_LOCK_IAUTH       (1 << 9)
+#define CEPH_LOCK_ILINK       (1 << 10)
+#define CEPH_LOCK_IXATTR      (1 << 11)
+#define CEPH_LOCK_IFLOCK      (1 << 12)  /* advisory file locks */
+#define CEPH_LOCK_IVERSION    (1 << 13)  /* mds internal */
+
+#define CEPH_LOCK_IFIRST      CEPH_LOCK_ISNAP
+
+
+/* client_session ops */
+enum {
+	CEPH_SESSION_REQUEST_OPEN,
+	CEPH_SESSION_OPEN,
+	CEPH_SESSION_REQUEST_CLOSE,
+	CEPH_SESSION_CLOSE,
+	CEPH_SESSION_REQUEST_RENEWCAPS,
+	CEPH_SESSION_RENEWCAPS,
+	CEPH_SESSION_STALE,
+	CEPH_SESSION_RECALL_STATE,
+	CEPH_SESSION_FLUSHMSG,
+	CEPH_SESSION_FLUSHMSG_ACK,
+	CEPH_SESSION_FORCE_RO,
+    // A response to REQUEST_OPEN indicating that the client should
+    // permanently desist from contacting the MDS
+	CEPH_SESSION_REJECT,
+        CEPH_SESSION_REQUEST_FLUSH_MDLOG
+};
+
+// flags for state reclaim
+#define CEPH_RECLAIM_RESET	1
+
+extern const char *ceph_session_op_name(int op);
+
+struct ceph_mds_session_head {
+	__le32 op;
+	__le64 seq;
+	struct ceph_timespec stamp;
+	__le32 max_caps, max_leases;
+} __attribute__ ((packed));
+
+/* client_request */
+/*
+ * metadata ops.
+ *  & 0x001000 -> write op
+ *  & 0x010000 -> follow symlink (e.g. stat(), not lstat()).
+ &  & 0x100000 -> use weird ino/path trace
+ */
+#define CEPH_MDS_OP_WRITE        0x001000
+enum {
+	CEPH_MDS_OP_LOOKUP     = 0x00100,
+	CEPH_MDS_OP_GETATTR    = 0x00101,
+	CEPH_MDS_OP_LOOKUPHASH = 0x00102,
+	CEPH_MDS_OP_LOOKUPPARENT = 0x00103,
+	CEPH_MDS_OP_LOOKUPINO  = 0x00104,
+	CEPH_MDS_OP_LOOKUPNAME = 0x00105,
+	CEPH_MDS_OP_GETVXATTR  = 0x00106,
+	CEPH_MDS_OP_DUMMY = 0x00107,
+
+	CEPH_MDS_OP_SETXATTR   = 0x01105,
+	CEPH_MDS_OP_RMXATTR    = 0x01106,
+	CEPH_MDS_OP_SETLAYOUT  = 0x01107,
+	CEPH_MDS_OP_SETATTR    = 0x01108,
+	CEPH_MDS_OP_SETFILELOCK= 0x01109,
+	CEPH_MDS_OP_GETFILELOCK= 0x00110,
+	CEPH_MDS_OP_SETDIRLAYOUT=0x0110a,
+
+	CEPH_MDS_OP_MKNOD      = 0x01201,
+	CEPH_MDS_OP_LINK       = 0x01202,
+	CEPH_MDS_OP_UNLINK     = 0x01203,
+	CEPH_MDS_OP_RENAME     = 0x01204,
+	CEPH_MDS_OP_MKDIR      = 0x01220,
+	CEPH_MDS_OP_RMDIR      = 0x01221,
+	CEPH_MDS_OP_SYMLINK    = 0x01222,
+
+	CEPH_MDS_OP_CREATE     = 0x01301,
+	CEPH_MDS_OP_OPEN       = 0x00302,
+	CEPH_MDS_OP_READDIR    = 0x00305,
+
+	CEPH_MDS_OP_LOOKUPSNAP = 0x00400,
+	CEPH_MDS_OP_MKSNAP     = 0x01400,
+	CEPH_MDS_OP_RMSNAP     = 0x01401,
+	CEPH_MDS_OP_LSSNAP     = 0x00402,
+	CEPH_MDS_OP_RENAMESNAP = 0x01403,
+	CEPH_MDS_OP_READDIR_SNAPDIFF   = 0x01404,
+
+	// internal op
+	CEPH_MDS_OP_FRAGMENTDIR= 0x01500,
+	CEPH_MDS_OP_EXPORTDIR  = 0x01501,
+	CEPH_MDS_OP_FLUSH      = 0x01502,
+	CEPH_MDS_OP_ENQUEUE_SCRUB  = 0x01503,
+	CEPH_MDS_OP_REPAIR_FRAGSTATS = 0x01504,
+	CEPH_MDS_OP_REPAIR_INODESTATS = 0x01505,
+	CEPH_MDS_OP_RDLOCK_FRAGSSTATS = 0x01507
+};
+
+#define IS_CEPH_MDS_OP_NEWINODE(op) (op == CEPH_MDS_OP_CREATE     || \
+				     op == CEPH_MDS_OP_MKNOD      || \
+				     op == CEPH_MDS_OP_MKDIR      || \
+				     op == CEPH_MDS_OP_SYMLINK)
+
+extern const char *ceph_mds_op_name(int op);
+
+// setattr mask is an int
+#ifndef CEPH_SETATTR_MODE
+#define CEPH_SETATTR_MODE		(1 << 0)
+#define CEPH_SETATTR_UID		(1 << 1)
+#define CEPH_SETATTR_GID		(1 << 2)
+#define CEPH_SETATTR_MTIME		(1 << 3)
+#define CEPH_SETATTR_ATIME		(1 << 4)
+#define CEPH_SETATTR_SIZE		(1 << 5)
+#define CEPH_SETATTR_CTIME		(1 << 6)
+#define CEPH_SETATTR_MTIME_NOW		(1 << 7)
+#define CEPH_SETATTR_ATIME_NOW		(1 << 8)
+#define CEPH_SETATTR_BTIME		(1 << 9)
+#define CEPH_SETATTR_KILL_SGUID		(1 << 10)
+#define CEPH_SETATTR_FSCRYPT_AUTH	(1 << 11)
+#define CEPH_SETATTR_FSCRYPT_FILE	(1 << 12)
+#define CEPH_SETATTR_KILL_SUID		(1 << 13)
+#define CEPH_SETATTR_KILL_SGID		(1 << 14)
+#endif
+
+/*
+ * open request flags
+ */
+#define CEPH_O_RDONLY          00000000
+#define CEPH_O_WRONLY          00000001
+#define CEPH_O_RDWR            00000002
+#define CEPH_O_CREAT           00000100
+#define CEPH_O_EXCL            00000200
+#define CEPH_O_TRUNC           00001000
+#define CEPH_O_LAZY            00020000
+#define CEPH_O_DIRECTORY       00200000
+#define CEPH_O_NOFOLLOW        00400000
+
+int ceph_flags_sys2wire(int flags);
+
+/*
+ * Ceph setxattr request flags.
+ */
+#define CEPH_XATTR_CREATE  (1 << 0)
+#define CEPH_XATTR_REPLACE (1 << 1)
+#define CEPH_XATTR_REMOVE  (1 << 31)
+
+/*
+ * readdir/readdir_snapdiff request flags;
+ */
+#define CEPH_READDIR_REPLY_BITFLAGS	(1<<0)
+
+/*
+ * readdir/readdir_snapdiff reply flags.
+ */
+#define CEPH_READDIR_FRAG_END		(1<<0)
+#define CEPH_READDIR_FRAG_COMPLETE	(1<<8)
+#define CEPH_READDIR_HASH_ORDER		(1<<9)
+#define CEPH_READDIR_OFFSET_HASH       (1<<10)
+
+/* Note that this is embedded wthin ceph_mds_request_head_legacy. */
+union ceph_mds_request_args_legacy {
+	struct {
+		__le32 mask;                 /* CEPH_CAP_* */
+	} __attribute__ ((packed)) getattr;
+	struct {
+		__le32 mode;
+		__le32 uid;
+		__le32 gid;
+		struct ceph_timespec mtime;
+		struct ceph_timespec atime;
+		__le64 size, old_size;       /* old_size needed by truncate */
+		__le32 mask;                 /* CEPH_SETATTR_* */
+	} __attribute__ ((packed)) setattr;
+	struct {
+		__le32 frag;                 /* which dir fragment */
+		__le32 max_entries;          /* how many dentries to grab */
+		__le32 max_bytes;
+		__le16 flags;
+               __le32 offset_hash;
+	} __attribute__ ((packed)) readdir;
+	struct {
+		__le32 mode;
+		__le32 rdev;
+	} __attribute__ ((packed)) mknod;
+	struct {
+		__le32 mode;
+	} __attribute__ ((packed)) mkdir;
+	struct {
+		__le32 flags;
+		__le32 mode;
+		__le32 stripe_unit;          /* layout for newly created file */
+		__le32 stripe_count;         /* ... */
+		__le32 object_size;
+		__le32 pool;                 /* if >= 0 and CREATEPOOLID feature */
+		__le32 mask;                 /* CEPH_CAP_* */
+		__le64 old_size;             /* if O_TRUNC */
+	} __attribute__ ((packed)) open;
+	struct {
+		__le32 flags;
+		__le32 osdmap_epoch; 	    /* use for set file/dir layout */
+	} __attribute__ ((packed)) setxattr;
+	struct {
+		struct ceph_file_layout layout;
+	} __attribute__ ((packed)) setlayout;
+	struct {
+		__u8 rule; /* currently fcntl or flock */
+		__u8 type; /* shared, exclusive, remove*/
+		__le64 owner; /* who requests/holds the lock */
+		__le64 pid; /* process id requesting the lock */
+		__le64 start; /* initial location to lock */
+		__le64 length; /* num bytes to lock from start */
+		__u8 wait; /* will caller wait for lock to become available? */
+	} __attribute__ ((packed)) filelock_change;
+} __attribute__ ((packed));
+
+#define CEPH_MDS_FLAG_REPLAY        1  /* this is a replayed op */
+#define CEPH_MDS_FLAG_WANT_DENTRY   2  /* want dentry in reply */
+#define CEPH_MDS_FLAG_ASYNC         4  /* request is async */
+
+struct ceph_mds_request_head_legacy {
+	__le64 oldest_client_tid;
+	__le32 mdsmap_epoch;           /* on client */
+	__le32 flags;                  /* CEPH_MDS_FLAG_* */
+	__u8 num_retry, num_fwd;       /* count retry, fwd attempts */
+	__le16 num_releases;           /* # include cap/lease release records */
+	__le32 op;                     /* mds op code */
+	__le32 caller_uid, caller_gid;
+	__le64 ino;                    /* use this ino for openc, mkdir, mknod,
+					  etc. (if replaying) */
+	union ceph_mds_request_args_legacy args;
+} __attribute__ ((packed));
+
+/*
+ * Note that this is embedded wthin ceph_mds_request_head. Also, compatibility
+ * with the ceph_mds_request_args_legacy must be maintained!
+ */
+union ceph_mds_request_args {
+	struct {
+		__le32 mask;                 /* CEPH_CAP_* */
+	} __attribute__ ((packed)) getattr;
+	struct {
+		__le32 mode;
+		__le32 uid;
+		__le32 gid;
+		struct ceph_timespec mtime;
+		struct ceph_timespec atime;
+		__le64 size, old_size;       /* old_size needed by truncate */
+		__le32 mask;                 /* CEPH_SETATTR_* */
+		struct ceph_timespec btime;
+	} __attribute__ ((packed)) setattr;
+	struct {
+		__le32 frag;                 /* which dir fragment */
+		__le32 max_entries;          /* how many dentries to grab */
+		__le32 max_bytes;
+		__le16 flags;
+               __le32 offset_hash;
+	} __attribute__ ((packed)) readdir;
+	struct {
+		__le32 mode;
+		__le32 rdev;
+	} __attribute__ ((packed)) mknod;
+	struct {
+		__le32 mode;
+	} __attribute__ ((packed)) mkdir;
+	struct {
+		__le32 flags;
+		__le32 mode;
+		__le32 stripe_unit;          /* layout for newly created file */
+		__le32 stripe_count;         /* ... */
+		__le32 object_size;
+		__le32 pool;                 /* if >= 0 and CREATEPOOLID feature */
+		__le32 mask;                 /* CEPH_CAP_* */
+		__le64 old_size;             /* if O_TRUNC */
+	} __attribute__ ((packed)) open;
+	struct {
+		__le32 flags;
+		__le32 osdmap_epoch; 	    /* use for set file/dir layout */
+	} __attribute__ ((packed)) setxattr;
+	struct {
+		struct ceph_file_layout layout;
+	} __attribute__ ((packed)) setlayout;
+	struct {
+		__u8 rule; /* currently fcntl or flock */
+		__u8 type; /* shared, exclusive, remove*/
+		__le64 owner; /* who requests/holds the lock */
+		__le64 pid; /* process id requesting the lock */
+		__le64 start; /* initial location to lock */
+		__le64 length; /* num bytes to lock from start */
+		__u8 wait; /* will caller wait for lock to become available? */
+	} __attribute__ ((packed)) filelock_change;
+	struct {
+		__le32 mask;                 /* CEPH_CAP_* */
+		__le64 snapid;
+		__le64 parent;
+		__le32 hash;
+	} __attribute__ ((packed)) lookupino;
+	struct {
+		__le32 frag;                 /* which dir fragment */
+		__le32 max_entries;          /* how many dentries to grab */
+		__le32 max_bytes;
+		__le16 flags;
+                __le32 offset_hash;
+		__le64 snap_other;
+	} __attribute__ ((packed)) snapdiff;
+} __attribute__ ((packed));
+
+#define CEPH_MDS_REQUEST_HEAD_VERSION	3
+
+/*
+ * Note that any change to this structure must ensure that it is compatible
+ * with ceph_mds_request_head_legacy.
+ */
+struct ceph_mds_request_head {
+	__le16 version;
+	__le64 oldest_client_tid;
+	__le32 mdsmap_epoch;           /* on client */
+	__le32 flags;                  /* CEPH_MDS_FLAG_* */
+	__u8 num_retry, num_fwd;       /* legacy count retry and fwd attempts */
+	__le16 num_releases;           /* # include cap/lease release records */
+	__le32 op;                     /* mds op code */
+	__le32 caller_uid, caller_gid;
+	__le64 ino;                    /* use this ino for openc, mkdir, mknod,
+					  etc. (if replaying) */
+	union ceph_mds_request_args args;
+
+	__le32 ext_num_retry;          /* new count retry attempts */
+	__le32 ext_num_fwd;            /* new count fwd attempts */
+
+	__le32 struct_len;             /* to store size of struct ceph_mds_request_head */
+	__le32 owner_uid, owner_gid;   /* used for OPs which create inodes */
+} __attribute__ ((packed));
+
+void inline encode(const struct ceph_mds_request_head& h, ceph::buffer::list& bl) {
+  using ceph::encode;
+  encode(h.version, bl);
+  encode(h.oldest_client_tid, bl);
+  encode(h.mdsmap_epoch, bl);
+  encode(h.flags, bl);
+
+  // For old MDS daemons
+  __u8 num_retry = __u32(h.ext_num_retry);
+  __u8 num_fwd = __u32(h.ext_num_fwd);
+  encode(num_retry, bl);
+  encode(num_fwd, bl);
+
+  encode(h.num_releases, bl);
+  encode(h.op, bl);
+  encode(h.caller_uid, bl);
+  encode(h.caller_gid, bl);
+  encode(h.ino, bl);
+  bl.append((char*)&h.args, sizeof(h.args));
+
+  if (h.version >= 2) {
+    encode(h.ext_num_retry, bl);
+    encode(h.ext_num_fwd, bl);
+  }
+
+  if (h.version >= 3) {
+    __u32 struct_len = sizeof(struct ceph_mds_request_head);
+    encode(struct_len, bl);
+    encode(h.owner_uid, bl);
+    encode(h.owner_gid, bl);
+
+    /*
+     * Please, add new fields handling here.
+     * You don't need to check h.version as we do it
+     * in decode(), because decode can properly skip
+     * all unsupported fields if h.version >= 3.
+     */
+  }
+}
+
+void inline decode(struct ceph_mds_request_head& h, ceph::buffer::list::const_iterator& bl) {
+  using ceph::decode;
+  unsigned struct_end = bl.get_off();
+
+  decode(h.version, bl);
+  decode(h.oldest_client_tid, bl);
+  decode(h.mdsmap_epoch, bl);
+  decode(h.flags, bl);
+  decode(h.num_retry, bl);
+  decode(h.num_fwd, bl);
+  decode(h.num_releases, bl);
+  decode(h.op, bl);
+  decode(h.caller_uid, bl);
+  decode(h.caller_gid, bl);
+  decode(h.ino, bl);
+  bl.copy(sizeof(h.args), (char*)&(h.args));
+
+  if (h.version >= 2) {
+    decode(h.ext_num_retry, bl);
+    decode(h.ext_num_fwd, bl);
+  } else {
+    h.ext_num_retry = h.num_retry;
+    h.ext_num_fwd = h.num_fwd;
+  }
+
+  if (h.version >= 3) {
+    decode(h.struct_len, bl);
+    struct_end += h.struct_len;
+
+    decode(h.owner_uid, bl);
+    decode(h.owner_gid, bl);
+  } else {
+    /*
+     * client is old: let's take caller_{u,g}id as owner_{u,g}id
+     * this is how it worked before adding of owner_{u,g}id fields.
+     */
+    h.owner_uid = h.caller_uid;
+    h.owner_gid = h.caller_gid;
+  }
+
+  /* add new fields handling here */
+
+  /*
+   * From version 3 we have struct_len field.
+   * It allows us to properly handle a case
+   * when client send struct ceph_mds_request_head
+   * bigger in size than MDS supports. In this
+   * case we just want to skip all remaining bytes
+   * at the end.
+   *
+   * See also DECODE_FINISH macro. Unfortunately,
+   * we can't start using it right now as it will be
+   * an incompatible protocol change.
+   */
+  if (h.version >= 3) {
+    if (bl.get_off() > struct_end)
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__));
+    if (bl.get_off() < struct_end)
+      bl += struct_end - bl.get_off();
+  }
+}
+
+/* cap/lease release record */
+struct ceph_mds_request_release {
+	__le64 ino, cap_id;            /* ino and unique cap id */
+	__le32 caps, wanted;           /* new issued, wanted */
+	__le32 seq, issue_seq, mseq;
+	__le32 dname_seq;              /* if releasing a dentry lease, a */
+	__le32 dname_len;              /* string follows. */
+} __attribute__ ((packed));
+
+static inline void
+copy_from_legacy_head(struct ceph_mds_request_head *head,
+			struct ceph_mds_request_head_legacy *legacy)
+{
+	struct ceph_mds_request_head_legacy *embedded_legacy =
+		(struct ceph_mds_request_head_legacy *)&head->oldest_client_tid;
+	*embedded_legacy = *legacy;
+}
+
+static inline void
+copy_to_legacy_head(struct ceph_mds_request_head_legacy *legacy,
+			struct ceph_mds_request_head *head)
+{
+	struct ceph_mds_request_head_legacy *embedded_legacy =
+		(struct ceph_mds_request_head_legacy *)&head->oldest_client_tid;
+	*legacy = *embedded_legacy;
+}
+
+/* client reply */
+struct ceph_mds_reply_head {
+	__le32 op;
+	__le32 result;
+	__le32 mdsmap_epoch;
+	__u8 safe;                     /* true if committed to disk */
+	__u8 is_dentry, is_target;     /* true if dentry, target inode records
+					  are included with reply */
+} __attribute__ ((packed));
+
+/* one for each node split */
+struct ceph_frag_tree_split {
+	__le32 frag;                   /* this frag splits... */
+	__le32 by;                     /* ...by this many bits */
+} __attribute__ ((packed));
+
+struct ceph_frag_tree_head {
+	__le32 nsplits;                /* num ceph_frag_tree_split records */
+	struct ceph_frag_tree_split splits[];
+} __attribute__ ((packed));
+
+/* capability issue, for bundling with mds reply */
+struct ceph_mds_reply_cap {
+	__le32 caps, wanted;           /* caps issued, wanted */
+	__le64 cap_id;
+	__le32 seq, mseq;
+	__le64 realm;                  /* snap realm */
+	__u8 flags;                    /* CEPH_CAP_FLAG_* */
+} __attribute__ ((packed));
+
+#define CEPH_CAP_FLAG_AUTH	(1 << 0)	/* cap is issued by auth mds */
+#define CEPH_CAP_FLAG_RELEASE	(1 << 1)        /* ask client to release the cap */
+
+/* reply_lease follows dname, and reply_inode */
+struct ceph_mds_reply_lease {
+	__le16 mask;            /* lease type(s) */
+	__le32 duration_ms;     /* lease duration */
+	__le32 seq;
+} __attribute__ ((packed));
+
+#define CEPH_LEASE_VALID	(1 | 2) /* old and new bit values */
+#define CEPH_LEASE_PRIMARY_LINK	4	/* primary linkage */
+
+struct ceph_mds_reply_dirfrag {
+	__le32 frag;            /* fragment */
+	__le32 auth;            /* auth mds, if this is a delegation point */
+	__le32 ndist;           /* number of mds' this is replicated on */
+	__le32 dist[];
+} __attribute__ ((packed));
+
+#define CEPH_LOCK_FCNTL		1
+#define CEPH_LOCK_FLOCK		2
+#define CEPH_LOCK_FCNTL_INTR	3
+#define CEPH_LOCK_FLOCK_INTR	4
+
+#define CEPH_LOCK_SHARED   1
+#define CEPH_LOCK_EXCL     2
+#define CEPH_LOCK_UNLOCK   4
+
+struct ceph_filelock {
+	__le64 start;/* file offset to start lock at */
+	__le64 length; /* num bytes to lock; 0 for all following start */
+	__le64 client; /* which client holds the lock */
+	__le64 owner; /* who requests/holds the lock */
+	__le64 pid; /* process id holding the lock on the client */
+	__u8 type; /* shared lock, exclusive lock, or unlock */
+} __attribute__ ((packed));
+
+
+/* file access modes */
+#define CEPH_FILE_MODE_PIN        0
+#define CEPH_FILE_MODE_RD         1
+#define CEPH_FILE_MODE_WR         2
+#define CEPH_FILE_MODE_RDWR       3  /* RD | WR */
+#define CEPH_FILE_MODE_LAZY       4  /* lazy io */
+#define CEPH_FILE_MODE_NUM        8  /* bc these are bit fields.. mostly */
+
+int ceph_flags_to_mode(int flags);
+
+/* inline data state */
+#define CEPH_INLINE_NONE	((__u64)-1)
+#define CEPH_INLINE_MAX_SIZE	CEPH_MIN_STRIPE_UNIT
+
+/* capability bits */
+#define CEPH_CAP_PIN         1  /* no specific capabilities beyond the pin */
+
+/* generic cap bits */
+/* note: these definitions are duplicated in mds/locks.c */
+#define CEPH_CAP_GSHARED     1  /* client can reads */
+#define CEPH_CAP_GEXCL       2  /* client can read and update */
+#define CEPH_CAP_GCACHE      4  /* (file) client can cache reads */
+#define CEPH_CAP_GRD         8  /* (file) client can read */
+#define CEPH_CAP_GWR        16  /* (file) client can write */
+#define CEPH_CAP_GBUFFER    32  /* (file) client can buffer writes */
+#define CEPH_CAP_GWREXTEND  64  /* (file) client can extend EOF */
+#define CEPH_CAP_GLAZYIO   128  /* (file) client can perform lazy io */
+
+#define CEPH_CAP_SIMPLE_BITS  2
+#define CEPH_CAP_FILE_BITS    8
+
+/* per-lock shift */
+#define CEPH_CAP_SAUTH      2
+#define CEPH_CAP_SLINK      4
+#define CEPH_CAP_SXATTR     6
+#define CEPH_CAP_SFILE      8
+
+/* composed values */
+#define CEPH_CAP_AUTH_SHARED  (CEPH_CAP_GSHARED  << CEPH_CAP_SAUTH)
+#define CEPH_CAP_AUTH_EXCL     (CEPH_CAP_GEXCL     << CEPH_CAP_SAUTH)
+#define CEPH_CAP_LINK_SHARED  (CEPH_CAP_GSHARED  << CEPH_CAP_SLINK)
+#define CEPH_CAP_LINK_EXCL     (CEPH_CAP_GEXCL     << CEPH_CAP_SLINK)
+#define CEPH_CAP_XATTR_SHARED (CEPH_CAP_GSHARED  << CEPH_CAP_SXATTR)
+#define CEPH_CAP_XATTR_EXCL    (CEPH_CAP_GEXCL     << CEPH_CAP_SXATTR)
+#define CEPH_CAP_FILE(x)       ((x) << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_SHARED   (CEPH_CAP_GSHARED   << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_EXCL     (CEPH_CAP_GEXCL     << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_CACHE    (CEPH_CAP_GCACHE    << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_RD       (CEPH_CAP_GRD       << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_WR       (CEPH_CAP_GWR       << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_BUFFER   (CEPH_CAP_GBUFFER   << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_WREXTEND (CEPH_CAP_GWREXTEND << CEPH_CAP_SFILE)
+#define CEPH_CAP_FILE_LAZYIO   (CEPH_CAP_GLAZYIO   << CEPH_CAP_SFILE)
+
+/* cap masks (for getattr) */
+#define CEPH_STAT_CAP_INODE    CEPH_CAP_PIN
+#define CEPH_STAT_CAP_TYPE     CEPH_CAP_PIN  /* mode >> 12 */
+#define CEPH_STAT_CAP_SYMLINK  CEPH_CAP_PIN
+#define CEPH_STAT_CAP_UID      CEPH_CAP_AUTH_SHARED
+#define CEPH_STAT_CAP_GID      CEPH_CAP_AUTH_SHARED
+#define CEPH_STAT_CAP_MODE     CEPH_CAP_AUTH_SHARED
+#define CEPH_STAT_CAP_NLINK    CEPH_CAP_LINK_SHARED
+#define CEPH_STAT_CAP_LAYOUT   CEPH_CAP_FILE_SHARED
+#define CEPH_STAT_CAP_MTIME    CEPH_CAP_FILE_SHARED
+#define CEPH_STAT_CAP_SIZE     CEPH_CAP_FILE_SHARED
+#define CEPH_STAT_CAP_ATIME    CEPH_CAP_FILE_SHARED  /* fixme */
+#define CEPH_STAT_CAP_XATTR    CEPH_CAP_XATTR_SHARED
+#define CEPH_STAT_CAP_INODE_ALL (CEPH_CAP_PIN |			\
+				 CEPH_CAP_AUTH_SHARED |	\
+				 CEPH_CAP_LINK_SHARED |	\
+				 CEPH_CAP_FILE_SHARED |	\
+				 CEPH_CAP_XATTR_SHARED)
+#define CEPH_STAT_CAP_INLINE_DATA (CEPH_CAP_FILE_SHARED | \
+				   CEPH_CAP_FILE_RD)
+#define CEPH_STAT_RSTAT        CEPH_CAP_FILE_WREXTEND
+
+#define CEPH_CAP_ANY_SHARED (CEPH_CAP_AUTH_SHARED |			\
+			      CEPH_CAP_LINK_SHARED |			\
+			      CEPH_CAP_XATTR_SHARED |			\
+			      CEPH_CAP_FILE_SHARED)
+#define CEPH_CAP_ANY_RD   (CEPH_CAP_ANY_SHARED | CEPH_CAP_FILE_RD |	\
+			   CEPH_CAP_FILE_CACHE)
+
+#define CEPH_CAP_ANY_EXCL (CEPH_CAP_AUTH_EXCL |		\
+			   CEPH_CAP_LINK_EXCL |		\
+			   CEPH_CAP_XATTR_EXCL |	\
+			   CEPH_CAP_FILE_EXCL)
+#define CEPH_CAP_ANY_FILE_RD (CEPH_CAP_FILE_RD | CEPH_CAP_FILE_CACHE | \
+                              CEPH_CAP_FILE_SHARED)
+#define CEPH_CAP_ANY_FILE_WR (CEPH_CAP_FILE_WR | CEPH_CAP_FILE_BUFFER |	\
+			      CEPH_CAP_FILE_EXCL)
+#define CEPH_CAP_ANY_WR   (CEPH_CAP_ANY_EXCL | CEPH_CAP_ANY_FILE_WR)
+#define CEPH_CAP_ANY      (CEPH_CAP_ANY_RD | CEPH_CAP_ANY_EXCL | \
+			   CEPH_CAP_ANY_FILE_WR | CEPH_CAP_FILE_LAZYIO | \
+			   CEPH_CAP_PIN)
+
+#define CEPH_CAP_LOCKS (CEPH_LOCK_IFILE | CEPH_LOCK_IAUTH | CEPH_LOCK_ILINK | \
+			CEPH_LOCK_IXATTR)
+
+/* cap masks async dir operations */
+#define CEPH_CAP_DIR_CREATE    CEPH_CAP_FILE_CACHE
+#define CEPH_CAP_DIR_UNLINK    CEPH_CAP_FILE_RD
+#define CEPH_CAP_ANY_DIR_OPS   (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_RD | \
+				CEPH_CAP_FILE_WREXTEND | CEPH_CAP_FILE_LAZYIO)
+
+
+int ceph_caps_for_mode(int mode);
+
+enum {
+	CEPH_CAP_OP_GRANT,         /* mds->client grant */
+	CEPH_CAP_OP_REVOKE,        /* mds->client revoke */
+	CEPH_CAP_OP_TRUNC,         /* mds->client trunc notify */
+	CEPH_CAP_OP_EXPORT,        /* mds has exported the cap */
+	CEPH_CAP_OP_IMPORT,        /* mds has imported the cap */
+	CEPH_CAP_OP_UPDATE,        /* client->mds update */
+	CEPH_CAP_OP_DROP,          /* client->mds drop cap bits */
+	CEPH_CAP_OP_FLUSH,         /* client->mds cap writeback */
+	CEPH_CAP_OP_FLUSH_ACK,     /* mds->client flushed */
+	CEPH_CAP_OP_FLUSHSNAP,     /* client->mds flush snapped metadata */
+	CEPH_CAP_OP_FLUSHSNAP_ACK, /* mds->client flushed snapped metadata */
+	CEPH_CAP_OP_RELEASE,       /* client->mds release (clean) cap */
+	CEPH_CAP_OP_RENEW,         /* client->mds renewal request */
+};
+
+extern const char *ceph_cap_op_name(int op);
+
+/* extra info for cap import/export */
+struct ceph_mds_cap_peer {
+	__le64 cap_id;
+	__le32 seq;
+	__le32 mseq;
+	__le32 mds;
+	__u8   flags;
+} __attribute__ ((packed));
+
+/*
+ * caps message, used for capability callbacks, acks, requests, etc.
+ */
+struct ceph_mds_caps_head {
+	__le32 op;                  /* CEPH_CAP_OP_* */
+	__le64 ino, realm;
+	__le64 cap_id;
+	__le32 seq, issue_seq;
+	__le32 caps, wanted, dirty; /* latest issued/wanted/dirty */
+	__le32 migrate_seq;
+	__le64 snap_follows;
+	__le32 snap_trace_len;
+
+	/* authlock */
+	__le32 uid, gid, mode;
+
+	/* linklock */
+	__le32 nlink;
+
+	/* xattrlock */
+	__le32 xattr_len;
+	__le64 xattr_version;
+} __attribute__ ((packed));
+
+struct ceph_mds_caps_non_export_body {
+    /* all except export */
+    /* filelock */
+    __le64 size, max_size, truncate_size;
+    __le32 truncate_seq;
+    struct ceph_timespec mtime, atime, ctime;
+    struct ceph_file_layout layout;
+    __le32 time_warp_seq;
+} __attribute__ ((packed));
+
+struct ceph_mds_caps_export_body {
+    /* export message */
+    struct ceph_mds_cap_peer peer;
+} __attribute__ ((packed));
+
+/* cap release msg head */
+struct ceph_mds_cap_release {
+	__le32 num;                /* number of cap_items that follow */
+} __attribute__ ((packed));
+
+struct ceph_mds_cap_item {
+	__le64 ino;
+	__le64 cap_id;
+	__le32 migrate_seq, seq;
+} __attribute__ ((packed));
+
+#define CEPH_MDS_LEASE_REVOKE           1  /*    mds  -> client */
+#define CEPH_MDS_LEASE_RELEASE          2  /* client  -> mds    */
+#define CEPH_MDS_LEASE_RENEW            3  /* client <-> mds    */
+#define CEPH_MDS_LEASE_REVOKE_ACK       4  /* client  -> mds    */
+
+extern const char *ceph_lease_op_name(int o);
+
+/* lease msg header */
+struct ceph_mds_lease {
+	__u8 action;            /* CEPH_MDS_LEASE_* */
+	__le16 mask;            /* which lease */
+	__le64 ino;
+	__le64 first, last;     /* snap range */
+	__le32 seq;
+	__le32 duration_ms;     /* duration of renewal */
+} __attribute__ ((packed));
+/* followed by a __le32+string for dname */
+
+/* client reconnect */
+struct ceph_mds_cap_reconnect {
+	__le64 cap_id;
+	__le32 wanted;
+	__le32 issued;
+	__le64 snaprealm;
+	__le64 pathbase;        /* base ino for our path to this ino */
+	__le32 flock_len;       /* size of flock state blob, if any */
+} __attribute__ ((packed));
+/* followed by flock blob */
+
+struct ceph_mds_cap_reconnect_v1 {
+	__le64 cap_id;
+	__le32 wanted;
+	__le32 issued;
+	__le64 size;
+	struct ceph_timespec mtime, atime;
+	__le64 snaprealm;
+	__le64 pathbase;        /* base ino for our path to this ino */
+} __attribute__ ((packed));
+
+struct ceph_mds_snaprealm_reconnect {
+	__le64 ino;     /* snap realm base */
+	__le64 seq;     /* snap seq for this snap realm */
+	__le64 parent;  /* parent realm */
+} __attribute__ ((packed));
+
+/*
+ * snaps
+ */
+enum {
+	CEPH_SNAP_OP_UPDATE,  /* CREATE or DESTROY */
+	CEPH_SNAP_OP_CREATE,
+	CEPH_SNAP_OP_DESTROY,
+	CEPH_SNAP_OP_SPLIT,
+};
+
+extern const char *ceph_snap_op_name(int o);
+
+/* snap msg header */
+struct ceph_mds_snap_head {
+	__le32 op;                /* CEPH_SNAP_OP_* */
+	__le64 split;             /* ino to split off, if any */
+	__le32 num_split_inos;    /* # inos belonging to new child realm */
+	__le32 num_split_realms;  /* # child realms udner new child realm */
+	__le32 trace_len;         /* size of snap trace blob */
+} __attribute__ ((packed));
+/* followed by split ino list, then split realms, then the trace blob */
+
+/*
+ * encode info about a snaprealm, as viewed by a client
+ */
+struct ceph_mds_snap_realm {
+	__le64 ino;           /* ino */
+	__le64 created;       /* snap: when created */
+	__le64 parent;        /* ino: parent realm */
+	__le64 parent_since;  /* snap: same parent since */
+	__le64 seq;           /* snap: version */
+	__le32 num_snaps;
+	__le32 num_prior_parent_snaps;
+} __attribute__ ((packed));
+/* followed by my snap list, then prior parent snap list */
+
+#ifndef __KERNEL__
+#undef __le16
+#undef __le32
+#undef __le64
+#endif
+
+#endif