[DLM] The core of the DLM for GFS2/CLVM

This is the core of the distributed lock manager which is required
to use GFS2 as a cluster filesystem. It is also used by CLVM and
can be used as a standalone lock manager independantly of either
of these two projects.

It implements VAX-style locking modes.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steve Whitehouse <swhiteho@redhat.com>

1 files changed, 312 insertions, 0 deletions

diff --git a/include/linux/dlm.h b/include/linux/dlm.h
new file mode 100644
index 000000000000..dd324ba44d80
--- /dev/null
+++ b/include/linux/dlm.h
@@ -0,0 +1,312 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**
+**  This copyrighted material is made available to anyone wishing to use,
+**  modify, copy, or redistribute it subject to the terms and conditions
+**  of the GNU General Public License v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+#ifndef __DLM_DOT_H__
+#define __DLM_DOT_H__
+
+/*
+ * Interface to Distributed Lock Manager (DLM)
+ * routines and structures to use DLM lockspaces
+ */
+
+/*
+ * Lock Modes
+ */
+
+#define DLM_LOCK_IV		-1	/* invalid */
+#define DLM_LOCK_NL		0	/* null */
+#define DLM_LOCK_CR		1	/* concurrent read */
+#define DLM_LOCK_CW		2	/* concurrent write */
+#define DLM_LOCK_PR		3	/* protected read */
+#define DLM_LOCK_PW		4	/* protected write */
+#define DLM_LOCK_EX		5	/* exclusive */
+
+/*
+ * Maximum size in bytes of a dlm_lock name
+ */
+
+#define DLM_RESNAME_MAXLEN	64
+
+/*
+ * Flags to dlm_lock
+ *
+ * DLM_LKF_NOQUEUE
+ *
+ * Do not queue the lock request on the wait queue if it cannot be granted
+ * immediately.  If the lock cannot be granted because of this flag, DLM will
+ * either return -EAGAIN from the dlm_lock call or will return 0 from
+ * dlm_lock and -EAGAIN in the lock status block when the AST is executed.
+ *
+ * DLM_LKF_CANCEL
+ *
+ * Used to cancel a pending lock request or conversion.  A converting lock is
+ * returned to its previously granted mode.
+ *
+ * DLM_LKF_CONVERT
+ *
+ * Indicates a lock conversion request.  For conversions the name and namelen
+ * are ignored and the lock ID in the LKSB is used to identify the lock.
+ *
+ * DLM_LKF_VALBLK
+ *
+ * Requests DLM to return the current contents of the lock value block in the
+ * lock status block.  When this flag is set in a lock conversion from PW or EX
+ * modes, DLM assigns the value specified in the lock status block to the lock
+ * value block of the lock resource.  The LVB is a DLM_LVB_LEN size array
+ * containing application-specific information.
+ *
+ * DLM_LKF_QUECVT
+ *
+ * Force a conversion request to be queued, even if it is compatible with
+ * the granted modes of other locks on the same resource.
+ *
+ * DLM_LKF_IVVALBLK
+ *
+ * Invalidate the lock value block.
+ *
+ * DLM_LKF_CONVDEADLK
+ *
+ * Allows the dlm to resolve conversion deadlocks internally by demoting the
+ * granted mode of a converting lock to NL.  The DLM_SBF_DEMOTED flag is
+ * returned for a conversion that's been effected by this.
+ *
+ * DLM_LKF_PERSISTENT
+ *
+ * Only relevant to locks originating in userspace.  A persistent lock will not
+ * be removed if the process holding the lock exits.
+ *
+ * DLM_LKF_NODLKWT
+ * DLM_LKF_NODLCKBLK
+ *
+ * net yet implemented
+ *
+ * DLM_LKF_EXPEDITE
+ *
+ * Used only with new requests for NL mode locks.  Tells the lock manager
+ * to grant the lock, ignoring other locks in convert and wait queues.
+ *
+ * DLM_LKF_NOQUEUEBAST
+ *
+ * Send blocking AST's before returning -EAGAIN to the caller.  It is only
+ * used along with the NOQUEUE flag.  Blocking AST's are not sent for failed
+ * NOQUEUE requests otherwise.
+ *
+ * DLM_LKF_HEADQUE
+ *
+ * Add a lock to the head of the convert or wait queue rather than the tail.
+ *
+ * DLM_LKF_NOORDER
+ *
+ * Disregard the standard grant order rules and grant a lock as soon as it
+ * is compatible with other granted locks.
+ *
+ * DLM_LKF_ORPHAN
+ *
+ * not yet implemented
+ *
+ * DLM_LKF_ALTPR
+ *
+ * If the requested mode cannot be granted immediately, try to grant the lock
+ * in PR mode instead.  If this alternate mode is granted instead of the
+ * requested mode, DLM_SBF_ALTMODE is returned in the lksb.
+ *
+ * DLM_LKF_ALTCW
+ *
+ * The same as ALTPR, but the alternate mode is CW.
+ *
+ * DLM_LKF_FORCEUNLOCK
+ *
+ * Unlock the lock even if it is converting or waiting or has sublocks.
+ * Only really for use by the userland device.c code.
+ *
+ */
+
+#define DLM_LKF_NOQUEUE		0x00000001
+#define DLM_LKF_CANCEL		0x00000002
+#define DLM_LKF_CONVERT		0x00000004
+#define DLM_LKF_VALBLK		0x00000008
+#define DLM_LKF_QUECVT		0x00000010
+#define DLM_LKF_IVVALBLK	0x00000020
+#define DLM_LKF_CONVDEADLK	0x00000040
+#define DLM_LKF_PERSISTENT	0x00000080
+#define DLM_LKF_NODLCKWT	0x00000100
+#define DLM_LKF_NODLCKBLK	0x00000200
+#define DLM_LKF_EXPEDITE	0x00000400
+#define DLM_LKF_NOQUEUEBAST	0x00000800
+#define DLM_LKF_HEADQUE		0x00001000
+#define DLM_LKF_NOORDER		0x00002000
+#define DLM_LKF_ORPHAN		0x00004000
+#define DLM_LKF_ALTPR		0x00008000
+#define DLM_LKF_ALTCW		0x00010000
+#define DLM_LKF_FORCEUNLOCK	0x00020000
+
+/*
+ * Some return codes that are not in errno.h
+ */
+
+#define DLM_ECANCEL		0x10001
+#define DLM_EUNLOCK		0x10002
+
+typedef void dlm_lockspace_t;
+
+/*
+ * Lock range structure
+ */
+
+struct dlm_range {
+	uint64_t ra_start;
+	uint64_t ra_end;
+};
+
+/*
+ * Lock status block
+ *
+ * Use this structure to specify the contents of the lock value block.  For a
+ * conversion request, this structure is used to specify the lock ID of the
+ * lock.  DLM writes the status of the lock request and the lock ID assigned
+ * to the request in the lock status block.
+ *
+ * sb_lkid: the returned lock ID.  It is set on new (non-conversion) requests.
+ * It is available when dlm_lock returns.
+ *
+ * sb_lvbptr: saves or returns the contents of the lock's LVB according to rules
+ * shown for the DLM_LKF_VALBLK flag.
+ *
+ * sb_flags: DLM_SBF_DEMOTED is returned if in the process of promoting a lock,
+ * it was first demoted to NL to avoid conversion deadlock.
+ * DLM_SBF_VALNOTVALID is returned if the resource's LVB is marked invalid.
+ *
+ * sb_status: the returned status of the lock request set prior to AST
+ * execution.  Possible return values:
+ *
+ * 0 if lock request was successful
+ * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
+ * -ENOMEM if there is no memory to process request
+ * -EINVAL if there are invalid parameters
+ * -DLM_EUNLOCK if unlock request was successful
+ * -DLM_ECANCEL if a cancel completed successfully
+ */
+
+#define DLM_SBF_DEMOTED		0x01
+#define DLM_SBF_VALNOTVALID	0x02
+#define DLM_SBF_ALTMODE		0x04
+
+struct dlm_lksb {
+	int 	 sb_status;
+	uint32_t sb_lkid;
+	char 	 sb_flags;
+	char *	 sb_lvbptr;
+};
+
+
+#ifdef __KERNEL__
+
+#define DLM_LSFL_NODIR		0x00000001
+
+/*
+ * dlm_new_lockspace
+ *
+ * Starts a lockspace with the given name.  If the named lockspace exists in
+ * the cluster, the calling node joins it.
+ */
+
+int dlm_new_lockspace(char *name, int namelen, dlm_lockspace_t **lockspace,
+		      uint32_t flags, int lvblen);
+
+/*
+ * dlm_release_lockspace
+ *
+ * Stop a lockspace.
+ */
+
+int dlm_release_lockspace(dlm_lockspace_t *lockspace, int force);
+
+/*
+ * dlm_lock
+ *
+ * Make an asyncronous request to acquire or convert a lock on a named
+ * resource.
+ *
+ * lockspace: context for the request
+ * mode: the requested mode of the lock (DLM_LOCK_)
+ * lksb: lock status block for input and async return values
+ * flags: input flags (DLM_LKF_)
+ * name: name of the resource to lock, can be binary
+ * namelen: the length in bytes of the resource name (MAX_RESNAME_LEN)
+ * parent: the lock ID of a parent lock or 0 if none
+ * lockast: function DLM executes when it completes processing the request
+ * astarg: argument passed to lockast and bast functions
+ * bast: function DLM executes when this lock later blocks another request
+ *
+ * Returns:
+ * 0 if request is successfully queued for processing
+ * -EINVAL if any input parameters are invalid
+ * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
+ * -ENOMEM if there is no memory to process request
+ * -ENOTCONN if there is a communication error
+ *
+ * If the call to dlm_lock returns an error then the operation has failed and
+ * the AST routine will not be called.  If dlm_lock returns 0 it is still
+ * possible that the lock operation will fail. The AST routine will be called
+ * when the locking is complete and the status is returned in the lksb.
+ *
+ * If the AST routines or parameter are passed to a conversion operation then
+ * they will overwrite those values that were passed to a previous dlm_lock
+ * call.
+ *
+ * AST routines should not block (at least not for long), but may make
+ * any locking calls they please.
+ */
+
+int dlm_lock(dlm_lockspace_t *lockspace,
+	     int mode,
+	     struct dlm_lksb *lksb,
+	     uint32_t flags,
+	     void *name,
+	     unsigned int namelen,
+	     uint32_t parent_lkid,
+	     void (*lockast) (void *astarg),
+	     void *astarg,
+	     void (*bast) (void *astarg, int mode),
+	     struct dlm_range *range);
+
+/*
+ * dlm_unlock
+ *
+ * Asynchronously release a lock on a resource.  The AST routine is called
+ * when the resource is successfully unlocked.
+ *
+ * lockspace: context for the request
+ * lkid: the lock ID as returned in the lksb
+ * flags: input flags (DLM_LKF_)
+ * lksb: if NULL the lksb parameter passed to last lock request is used
+ * astarg: the arg used with the completion ast for the unlock
+ *
+ * Returns:
+ * 0 if request is successfully queued for processing
+ * -EINVAL if any input parameters are invalid
+ * -ENOTEMPTY if the lock still has sublocks
+ * -EBUSY if the lock is waiting for a remote lock operation
+ * -ENOTCONN if there is a communication error
+ */
+
+int dlm_unlock(dlm_lockspace_t *lockspace,
+	       uint32_t lkid,
+	       uint32_t flags,
+	       struct dlm_lksb *lksb,
+	       void *astarg);
+
+#endif				/* __KERNEL__ */
+
+#endif				/* __DLM_DOT_H__ */
+