bsd/kern/kern_lockf.c

7  * as defined in and that are subject to the Apple Public Source License
9  * compliance with the License. The rights granted to you under the License
10  * may not be used to create, or enable the creation or redistribution of,
11  * unlawful or unlicensed copies of an Apple operating system, or to
32  * This code is derived from software contributed to Berkeley by
44  *    may be used to endorse or promote products derived from this software
141  * Parameters:	ap			Argument pointer to a vnop_advlock_args
143  *					lock operation to be attempted.
156  * Notes:	We return ENOLCK when we run out of memory to support locks; as
202 		 * It's OK to cast the u_quad_t to and off_t here, since they
204 		 * contents will never overflow into the sign bit.  We need to
205 		 * do this because we will use size to force range checks.
326 			 * currently blocked F_SETLK request to
327 			 * return to userland with an errno.
337  * and mark them as blocked by a different lock ("to").  Used in the case
338  * where a byte range currently occupied by "from" is to be occupied by "to."
341 lf_move_blocked(struct lockf *to, struct lockf *from)
346 		tlock->lf_next = to;
349 	TAILQ_CONCAT(&to->lf_blkhd, &from->lf_blkhd, lf_block);
360  *					to already locked regions, and which
381 		 * and belong to the same owner, then they are adjacent on the list.
397 		/* If the lock starts adjacent to us, we can coalesce it */
413 		/* no matching conditions; go on to next lock */
425  *					to be set; allocated by the caller, it
437  * Notes:	We add the lock to the provisional lock list.  We do not
484 		 * wait channels to see if there are any cycles that
485 		 * involve us. MAXDEPTH is set just to make sure we
504 				 * cycle to see if the lock is blocked behind
565 		 * Add our lock to the blocked list and sleep until we're free.
587 			 * lf_wakelock() always sets wakelock->lf_next to
655 			 * able to acquire it.
694 			 * If downgrading lock, others may be able to
765  *		lock (or an overlap to that lock) and remove it (or shrink
768  * Parameters:	unlock			The lock to clear
796 		 * Wakeup the list of locks to be retried.
855  * Parameters:	lock			Pointer to lock to test for blocks
856  *		fl			Pointer to flock structure to receive
859  *		matchpid		-1, or pid value to match in lookup.
864  *		*fl			Contents modified to reflect the
868  * Notes:	fl->l_pid will be (-1) for file locks and will only be set to
904  *		the lock owner; otherwise, we are permitted to upgrade or
909  *		matchpid		-1, or pid value to match in lookup.
946  * Description:	Walk the list of locks to find an overlapping lock (if any).
951  *		prev			pointer to pointer pointer to contain
952  *					address of pointer to previous lock
953  *					pointer to overlapping lock, if overlap
954  *		overlap			pointer to pointer to contain address
966  *					lock previous to the overlapping lock;
967  *					this is generally used to relink the
969  *		*overlap		The pointer to the overlapping lock
970  *					itself; this is used to return data in
972  *					caller to modify the overlapping lock,
977  *		while lf_setlock will iterate over all overlapping locks to
1007 			 * Locks belonging to one process are adjacent on the
1008 			 * list, so if we've found any locks belonging to us,
1012 			 * numerically adjacent locks from the same owner to
1089  * Parameters:	lock1			Lock to split
1103  *		locks, and there is insufficient memory to allocate the third
1118 	 * Check to see if spliting into only two pieces.
1157  * waiting on the lock may now be able to acquire it.
1192 			 * move them to the wakelock list instead, and then