Differential D7688 Diff 19873 head/sys/vm/swap_pager.c

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head/sys/vm/swap_pager.c

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	* There may be no processes swapped out to the device.			* There may be no processes swapped out to the device.
	*			*
	* This routine may block.			* This routine may block.
	*/			*/
	static void			static void
	swap_pager_swapoff(struct swdevt *sp)			swap_pager_swapoff(struct swdevt *sp)
	{			{
	struct swblock *swap;			struct swblock *swap;
				vm_object_t locked_obj, object;
				vm_pindex_t pindex;
	int i, j, retries;			int i, j, retries;

	sx_assert(&swdev_syscall_lock, SA_XLOCKED);			sx_assert(&swdev_syscall_lock, SA_XLOCKED);

	retries = 0;			retries = 0;
				locked_obj = NULL;
	full_rescan:			full_rescan:
	mtx_lock(&swhash_mtx);			mtx_lock(&swhash_mtx);
	for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */			for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
	restart:			restart:
	for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {			for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
	vm_object_t object = swap->swb_object;			object = swap->swb_object;
	vm_pindex_t pindex = swap->swb_index;			pindex = swap->swb_index;
	for (j = 0; j < SWAP_META_PAGES; ++j) {			for (j = 0; j < SWAP_META_PAGES; ++j) {
	if (swp_pager_isondev(swap->swb_pages[j], sp)) {			if (!swp_pager_isondev(swap->swb_pages[j], sp))
	/* avoid deadlock */			continue;
				if (locked_obj != object) {
				if (locked_obj != NULL)
				VM_OBJECT_WUNLOCK(locked_obj);
				locked_obj = object;
	if (!VM_OBJECT_TRYWLOCK(object)) {			if (!VM_OBJECT_TRYWLOCK(object)) {
	break;
	} else {
	mtx_unlock(&swhash_mtx);			mtx_unlock(&swhash_mtx);
	swp_pager_force_pagein(object,			/* Depends on type-stability. */
	pindex + j);			VM_OBJECT_WLOCK(object);
	VM_OBJECT_WUNLOCK(object);
	mtx_lock(&swhash_mtx);			mtx_lock(&swhash_mtx);
	goto restart;			goto restart;
	}			}
	}			}
				MPASS(locked_obj == object);
				mtx_unlock(&swhash_mtx);
				swp_pager_force_pagein(object, pindex + j);
				mtx_lock(&swhash_mtx);
				goto restart;
	}			}
	}			}
	}			}
	mtx_unlock(&swhash_mtx);			mtx_unlock(&swhash_mtx);
				if (locked_obj != NULL) {
				VM_OBJECT_WUNLOCK(locked_obj);
				locked_obj = NULL;
				}
	if (sp->sw_used) {			if (sp->sw_used) {
	/*			/*
	* Objects may be locked or paging to the device being			* Objects may be locked or paging to the device being
	* removed, so we will miss their pages and need to			* removed, so we will miss their pages and need to
	* make another pass. We have marked this device as			* make another pass. We have marked this device as
	* SW_CLOSING, so the activity should finish soon.			* SW_CLOSING, so the activity should finish soon.
	*/			*/
	retries++;			retries++;
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