include/uapi/linux/dlmconstants.h

Source file repositories/reference/linux-study-clean/include/uapi/linux/dlmconstants.h

File Facts

System
Linux kernel
Corpus path
include/uapi/linux/dlmconstants.h
Extension
.h
Size
5091 bytes
Lines
168
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __DLMCONSTANTS_DOT_H__
#define __DLMCONSTANTS_DOT_H__

/*
 * Constants used by DLM interface.
 */

#define DLM_LOCKSPACE_LEN       64
#define DLM_RESNAME_MAXLEN      64


/*
 * 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 */


/*
 * 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_NODLCKWT
 *
 * Do not cancel the lock if it gets into conversion deadlock.
 *
 * 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.

Annotation

Implementation Notes