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dlm_nsjoin(3)
NAME
  dlm_nsjoin - Connects the process to the specified resource namespace
  (provided in Production Server configurations only)

LIBRARY
  Distributed Lock Manager Library (libdlm.a)

SYNOPSIS
  #include <sys/dlm.h>

  dlm_status_t dlm_nsjoin (
	  dlm_nsid_t nsid,
	  dlm_nsp_t *nsp,
	  dlm_flags_t flags );

PARAMETERS
  nsid	    Identifies the resource namespace. Specify either a zero (0) for
	    a systemwide namespace, a user ID (UID), or a group ID (GID).
	    The process must hold this ID for access to the namespace to be
	    granted.

  nsp	    Receives a handle that identifies the namespace.  An application
	    supplies this handle on subsequent calls to the dlm_lock,
	    dlm_locktp, dlm_quelock, and dlm_quelocktp functions when
	    creating a root lock in the namespace.

  flags	    Specifies flags that modify the operation. The flags parameter is
	    a bit mask that is the logical OR of each bit set, where each bit
	    corresponds to an option.

	    The dlm_flags_t structure defines a symbolic name for each flag
	    bit. The following list describes each flag:

	    DLM_GROUP Indicates that nsid specifies an effective group ID
		      (EGID) qualified namespace.  The process must be a
		      member of this group.

	    DLM_USER  Indicates that  nsid specifies an effective user ID
		      (EUID) qualified namespace.  The process must hold this
		      user ID.	A user ID of zero (0) indicates a systemwide
		      namespace.  In that case, the process must have root
		      privilege.

DESCRIPTION
  The dlm_nsjoin function connects the process to the specified namespace for
  locking.


  A namespace can be viewed as a container for resource names. Multiple
  namespaces exist to provide separation of unrelated applications for
  reasons of security and modularity.  The namespaces are qualified by either
  EUID or EGID.


  The application must request access to a namespace before attempting to
  acquire a lock on a resource in that namespace.  The distributed lock
  manager (DLM) verifies that the application is permitted to access the
  indicated  namespace by verifying that the process holds the appropriate
  group ID, user ID, or root privilege as needed for that namespace.  The
  lock manager returns a handle to the namespace.  The application presents
  this handle on subsequent calls to acquire root locks. Sublocks can be
  added to a root lock without further access checks.

  The DLM_NSPROCMAX symbol specifies the maximum number of namespaces of
  which a process can be a member.  A process can join, leave, and then
  rejoin the same namespace.  After a process has joined a namespace,
  subsequent calls to the dlm_nsjoin function for the same namespace will
  fail until the process successfully completes a dlm_nsleave request for
  that namespace.

  It is the cluster administrator's responsibility to keep namespaces (for
  instance group and user IDs) consistent across the cluster.

RETURN VALUES
  Upon completion, the dlm_nsjoin function returns one of the following
  values:

  DLM_SUCCESS
	    Connection was made to the namespace and a handle was returned.

  DLM_ATTACHED
	    This process has already joined the namespace.

  DLM_BADPARAM
	    The nsp parameter was not specified or an illegal flag was
	    specified.

  DLM_EFAULT
	    An error occurred in the copy operation to or from the DLM
	    database.

  DLM_ENOSYS
	    The lock subsystem is not loaded.

  DLM_NOACCESS
	    This process is not permitted access to the namespace.

  DLM_TOMANYNS
	    This process is not able to join any more namespaces because it
	    has already attached to the maximum number of namespaces, as
	    specified by the DLM_NSPROCMAX symbol.

FILES
  /usr/include/sys/dlm.h
	    DLM library header file.

  /usr/examples/cluster/api_ex_master.c|api_ex_client.c
	    Source file for an example showing lock conversion and value
	    block usage.



RELATED INFORMATION
  Functions: dlm_cancel(3), dlm_cvt(3), dlm_detach(3), dlm_get_lkinfo(3),
  dlm_get_rsbinfo(3), dlm_glc_attach(3), dlm_glc_create(3),
  dlm_glc_detach(3), dlm_glc_destroy(3), dlm_lock(3), dlm_notify(3),
  dlm_nsleave(3), dlm_perrno(3), dlm_quecvt(3), dlm_quelock(3),
  dlm_rd_attach(3), dlm_rd_collect(3), dlm_rd_detach(3), dlm_rd_validate(3),
  dlm_set_signal(3), dlm_unlock(3)

  File: dlm(4)

  TruCluster Production Server Software Application Programming Interfaces

Index for Section 3

Alphabetical listing for D

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