freebsd-dev/sys/vm/vm_radix.c
Alan Cox 776cad90ff Addendum to r254141: The call to vm_radix_insert() in vm_page_cache() can
reclaim the last preexisting cached page in the object, resulting in a call
to vdrop().  Detect this scenario so that the vnode's hold count is
correctly maintained.  Otherwise, we panic.

Reported by:	scottl
Tested by:	pho
Discussed with:	attilio, jeff, kib
2013-08-23 17:27:12 +00:00

859 lines
22 KiB
C

/*
* Copyright (c) 2013 EMC Corp.
* Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org>
* Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* Path-compressed radix trie implementation.
* The following code is not generalized into a general purpose library
* because there are way too many parameters embedded that should really
* be decided by the library consumers. At the same time, consumers
* of this code must achieve highest possible performance.
*
* The implementation takes into account the following rationale:
* - Size of the nodes should be as small as possible but still big enough
* to avoid a large maximum depth for the trie. This is a balance
* between the necessity to not wire too much physical memory for the nodes
* and the necessity to avoid too much cache pollution during the trie
* operations.
* - There is not a huge bias toward the number of lookup operations over
* the number of insert and remove operations. This basically implies
* that optimizations supposedly helping one operation but hurting the
* other might be carefully evaluated.
* - On average not many nodes are expected to be fully populated, hence
* level compression may just complicate things.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/vmmeter.h>
#include <vm/uma.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_page.h>
#include <vm/vm_radix.h>
#ifdef DDB
#include <ddb/ddb.h>
#endif
/*
* These widths should allow the pointers to a node's children to fit within
* a single cache line. The extra levels from a narrow width should not be
* a problem thanks to path compression.
*/
#ifdef __LP64__
#define VM_RADIX_WIDTH 4
#else
#define VM_RADIX_WIDTH 3
#endif
#define VM_RADIX_COUNT (1 << VM_RADIX_WIDTH)
#define VM_RADIX_MASK (VM_RADIX_COUNT - 1)
#define VM_RADIX_LIMIT \
(howmany((sizeof(vm_pindex_t) * NBBY), VM_RADIX_WIDTH) - 1)
/* Flag bits stored in node pointers. */
#define VM_RADIX_ISLEAF 0x1
#define VM_RADIX_FLAGS 0x1
#define VM_RADIX_PAD VM_RADIX_FLAGS
/* Returns one unit associated with specified level. */
#define VM_RADIX_UNITLEVEL(lev) \
((vm_pindex_t)1 << ((lev) * VM_RADIX_WIDTH))
struct vm_radix_node {
vm_pindex_t rn_owner; /* Owner of record. */
uint16_t rn_count; /* Valid children. */
uint16_t rn_clev; /* Current level. */
void *rn_child[VM_RADIX_COUNT]; /* Child nodes. */
};
static uma_zone_t vm_radix_node_zone;
/*
* Allocate a radix node.
*/
static __inline struct vm_radix_node *
vm_radix_node_get(vm_pindex_t owner, uint16_t count, uint16_t clevel)
{
struct vm_radix_node *rnode;
rnode = uma_zalloc(vm_radix_node_zone, M_NOWAIT | M_ZERO);
if (rnode == NULL)
return (NULL);
rnode->rn_owner = owner;
rnode->rn_count = count;
rnode->rn_clev = clevel;
return (rnode);
}
/*
* Free radix node.
*/
static __inline void
vm_radix_node_put(struct vm_radix_node *rnode)
{
uma_zfree(vm_radix_node_zone, rnode);
}
/*
* Return the position in the array for a given level.
*/
static __inline int
vm_radix_slot(vm_pindex_t index, uint16_t level)
{
return ((index >> (level * VM_RADIX_WIDTH)) & VM_RADIX_MASK);
}
/* Trims the key after the specified level. */
static __inline vm_pindex_t
vm_radix_trimkey(vm_pindex_t index, uint16_t level)
{
vm_pindex_t ret;
ret = index;
if (level > 0) {
ret >>= level * VM_RADIX_WIDTH;
ret <<= level * VM_RADIX_WIDTH;
}
return (ret);
}
/*
* Get the root node for a radix tree.
*/
static __inline struct vm_radix_node *
vm_radix_getroot(struct vm_radix *rtree)
{
return ((struct vm_radix_node *)rtree->rt_root);
}
/*
* Set the root node for a radix tree.
*/
static __inline void
vm_radix_setroot(struct vm_radix *rtree, struct vm_radix_node *rnode)
{
rtree->rt_root = (uintptr_t)rnode;
}
/*
* Returns TRUE if the specified radix node is a leaf and FALSE otherwise.
*/
static __inline boolean_t
vm_radix_isleaf(struct vm_radix_node *rnode)
{
return (((uintptr_t)rnode & VM_RADIX_ISLEAF) != 0);
}
/*
* Returns the associated page extracted from rnode.
*/
static __inline vm_page_t
vm_radix_topage(struct vm_radix_node *rnode)
{
return ((vm_page_t)((uintptr_t)rnode & ~VM_RADIX_FLAGS));
}
/*
* Adds the page as a child of the provided node.
*/
static __inline void
vm_radix_addpage(struct vm_radix_node *rnode, vm_pindex_t index, uint16_t clev,
vm_page_t page)
{
int slot;
slot = vm_radix_slot(index, clev);
rnode->rn_child[slot] = (void *)((uintptr_t)page | VM_RADIX_ISLEAF);
}
/*
* Returns the slot where two keys differ.
* It cannot accept 2 equal keys.
*/
static __inline uint16_t
vm_radix_keydiff(vm_pindex_t index1, vm_pindex_t index2)
{
uint16_t clev;
KASSERT(index1 != index2, ("%s: passing the same key value %jx",
__func__, (uintmax_t)index1));
index1 ^= index2;
for (clev = VM_RADIX_LIMIT;; clev--)
if (vm_radix_slot(index1, clev) != 0)
return (clev);
}
/*
* Returns TRUE if it can be determined that key does not belong to the
* specified rnode. Otherwise, returns FALSE.
*/
static __inline boolean_t
vm_radix_keybarr(struct vm_radix_node *rnode, vm_pindex_t idx)
{
if (rnode->rn_clev < VM_RADIX_LIMIT) {
idx = vm_radix_trimkey(idx, rnode->rn_clev + 1);
return (idx != rnode->rn_owner);
}
return (FALSE);
}
/*
* Internal helper for vm_radix_reclaim_allnodes().
* This function is recursive.
*/
static void
vm_radix_reclaim_allnodes_int(struct vm_radix_node *rnode)
{
int slot;
KASSERT(rnode->rn_count <= VM_RADIX_COUNT,
("vm_radix_reclaim_allnodes_int: bad count in rnode %p", rnode));
for (slot = 0; rnode->rn_count != 0; slot++) {
if (rnode->rn_child[slot] == NULL)
continue;
if (!vm_radix_isleaf(rnode->rn_child[slot]))
vm_radix_reclaim_allnodes_int(rnode->rn_child[slot]);
rnode->rn_child[slot] = NULL;
rnode->rn_count--;
}
vm_radix_node_put(rnode);
}
#ifdef INVARIANTS
/*
* Radix node zone destructor.
*/
static void
vm_radix_node_zone_dtor(void *mem, int size __unused, void *arg __unused)
{
struct vm_radix_node *rnode;
int slot;
rnode = mem;
KASSERT(rnode->rn_count == 0,
("vm_radix_node_put: rnode %p has %d children", rnode,
rnode->rn_count));
for (slot = 0; slot < VM_RADIX_COUNT; slot++)
KASSERT(rnode->rn_child[slot] == NULL,
("vm_radix_node_put: rnode %p has a child", rnode));
}
#endif
#ifndef UMA_MD_SMALL_ALLOC
/*
* Reserve the KVA necessary to satisfy the node allocation.
* This is mandatory in architectures not supporting direct
* mapping as they will need otherwise to carve into the kernel maps for
* every node allocation, resulting into deadlocks for consumers already
* working with kernel maps.
*/
static void
vm_radix_reserve_kva(void *arg __unused)
{
/*
* Calculate the number of reserved nodes, discounting the pages that
* are needed to store them.
*/
if (!uma_zone_reserve_kva(vm_radix_node_zone,
((vm_paddr_t)cnt.v_page_count * PAGE_SIZE) / (PAGE_SIZE +
sizeof(struct vm_radix_node))))
panic("%s: unable to reserve KVA", __func__);
}
SYSINIT(vm_radix_reserve_kva, SI_SUB_KMEM, SI_ORDER_SECOND,
vm_radix_reserve_kva, NULL);
#endif
/*
* Initialize the UMA slab zone.
* Until vm_radix_prealloc() is called, the zone will be served by the
* UMA boot-time pre-allocated pool of pages.
*/
void
vm_radix_init(void)
{
vm_radix_node_zone = uma_zcreate("RADIX NODE",
sizeof(struct vm_radix_node), NULL,
#ifdef INVARIANTS
vm_radix_node_zone_dtor,
#else
NULL,
#endif
NULL, NULL, VM_RADIX_PAD, UMA_ZONE_VM);
}
/*
* Inserts the key-value pair into the trie.
* Panics if the key already exists.
*/
int
vm_radix_insert(struct vm_radix *rtree, vm_page_t page)
{
vm_pindex_t index, newind;
void **parentp;
struct vm_radix_node *rnode, *tmp;
vm_page_t m;
int slot;
uint16_t clev;
index = page->pindex;
restart:
/*
* The owner of record for root is not really important because it
* will never be used.
*/
rnode = vm_radix_getroot(rtree);
if (rnode == NULL) {
rtree->rt_root = (uintptr_t)page | VM_RADIX_ISLEAF;
return (0);
}
parentp = (void **)&rtree->rt_root;
for (;;) {
if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex == index)
panic("%s: key %jx is already present",
__func__, (uintmax_t)index);
clev = vm_radix_keydiff(m->pindex, index);
/*
* During node allocation the trie that is being
* walked can be modified because of recursing radix
* trie operations.
* If this is the case, the recursing functions signal
* such situation and the insert operation must
* start from scratch again.
* The freed radix node will then be in the UMA
* caches very likely to avoid the same situation
* to happen.
*/
rtree->rt_flags |= RT_INSERT_INPROG;
tmp = vm_radix_node_get(vm_radix_trimkey(index,
clev + 1), 2, clev);
rtree->rt_flags &= ~RT_INSERT_INPROG;
if (tmp == NULL) {
rtree->rt_flags &= ~RT_TRIE_MODIFIED;
return (ENOMEM);
}
if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) {
rtree->rt_flags &= ~RT_TRIE_MODIFIED;
tmp->rn_count = 0;
vm_radix_node_put(tmp);
goto restart;
}
*parentp = tmp;
vm_radix_addpage(tmp, index, clev, page);
vm_radix_addpage(tmp, m->pindex, clev, m);
return (0);
} else if (vm_radix_keybarr(rnode, index))
break;
slot = vm_radix_slot(index, rnode->rn_clev);
if (rnode->rn_child[slot] == NULL) {
rnode->rn_count++;
vm_radix_addpage(rnode, index, rnode->rn_clev, page);
return (0);
}
parentp = &rnode->rn_child[slot];
rnode = rnode->rn_child[slot];
}
/*
* A new node is needed because the right insertion level is reached.
* Setup the new intermediate node and add the 2 children: the
* new object and the older edge.
*/
newind = rnode->rn_owner;
clev = vm_radix_keydiff(newind, index);
/* See the comments above. */
rtree->rt_flags |= RT_INSERT_INPROG;
tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev);
rtree->rt_flags &= ~RT_INSERT_INPROG;
if (tmp == NULL) {
rtree->rt_flags &= ~RT_TRIE_MODIFIED;
return (ENOMEM);
}
if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) {
rtree->rt_flags &= ~RT_TRIE_MODIFIED;
tmp->rn_count = 0;
vm_radix_node_put(tmp);
goto restart;
}
*parentp = tmp;
vm_radix_addpage(tmp, index, clev, page);
slot = vm_radix_slot(newind, clev);
tmp->rn_child[slot] = rnode;
return (0);
}
/*
* Returns TRUE if the specified radix tree contains a single leaf and FALSE
* otherwise.
*/
boolean_t
vm_radix_is_singleton(struct vm_radix *rtree)
{
struct vm_radix_node *rnode;
rnode = vm_radix_getroot(rtree);
if (rnode == NULL)
return (FALSE);
return (vm_radix_isleaf(rnode));
}
/*
* Returns the value stored at the index. If the index is not present,
* NULL is returned.
*/
vm_page_t
vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
{
struct vm_radix_node *rnode;
vm_page_t m;
int slot;
rnode = vm_radix_getroot(rtree);
while (rnode != NULL) {
if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex == index)
return (m);
else
break;
} else if (vm_radix_keybarr(rnode, index))
break;
slot = vm_radix_slot(index, rnode->rn_clev);
rnode = rnode->rn_child[slot];
}
return (NULL);
}
/*
* Look up the nearest entry at a position bigger than or equal to index.
*/
vm_page_t
vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
{
struct vm_radix_node *stack[VM_RADIX_LIMIT];
vm_pindex_t inc;
vm_page_t m;
struct vm_radix_node *child, *rnode;
#ifdef INVARIANTS
int loops = 0;
#endif
int slot, tos;
rnode = vm_radix_getroot(rtree);
if (rnode == NULL)
return (NULL);
else if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex >= index)
return (m);
else
return (NULL);
}
tos = 0;
for (;;) {
/*
* If the keys differ before the current bisection node,
* then the search key might rollback to the earliest
* available bisection node or to the smallest key
* in the current node (if the owner is bigger than the
* search key).
*/
if (vm_radix_keybarr(rnode, index)) {
if (index > rnode->rn_owner) {
ascend:
KASSERT(++loops < 1000,
("vm_radix_lookup_ge: too many loops"));
/*
* Pop nodes from the stack until either the
* stack is empty or a node that could have a
* matching descendant is found.
*/
do {
if (tos == 0)
return (NULL);
rnode = stack[--tos];
} while (vm_radix_slot(index,
rnode->rn_clev) == (VM_RADIX_COUNT - 1));
/*
* The following computation cannot overflow
* because index's slot at the current level
* is less than VM_RADIX_COUNT - 1.
*/
index = vm_radix_trimkey(index,
rnode->rn_clev);
index += VM_RADIX_UNITLEVEL(rnode->rn_clev);
} else
index = rnode->rn_owner;
KASSERT(!vm_radix_keybarr(rnode, index),
("vm_radix_lookup_ge: keybarr failed"));
}
slot = vm_radix_slot(index, rnode->rn_clev);
child = rnode->rn_child[slot];
if (vm_radix_isleaf(child)) {
m = vm_radix_topage(child);
if (m->pindex >= index)
return (m);
} else if (child != NULL)
goto descend;
/*
* Look for an available edge or page within the current
* bisection node.
*/
if (slot < (VM_RADIX_COUNT - 1)) {
inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
index = vm_radix_trimkey(index, rnode->rn_clev);
do {
index += inc;
slot++;
child = rnode->rn_child[slot];
if (vm_radix_isleaf(child)) {
m = vm_radix_topage(child);
if (m->pindex >= index)
return (m);
} else if (child != NULL)
goto descend;
} while (slot < (VM_RADIX_COUNT - 1));
}
KASSERT(child == NULL || vm_radix_isleaf(child),
("vm_radix_lookup_ge: child is radix node"));
/*
* If a page or edge bigger than the search slot is not found
* in the current node, ascend to the next higher-level node.
*/
goto ascend;
descend:
KASSERT(rnode->rn_clev > 0,
("vm_radix_lookup_ge: pushing leaf's parent"));
KASSERT(tos < VM_RADIX_LIMIT,
("vm_radix_lookup_ge: stack overflow"));
stack[tos++] = rnode;
rnode = child;
}
}
/*
* Look up the nearest entry at a position less than or equal to index.
*/
vm_page_t
vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
{
struct vm_radix_node *stack[VM_RADIX_LIMIT];
vm_pindex_t inc;
vm_page_t m;
struct vm_radix_node *child, *rnode;
#ifdef INVARIANTS
int loops = 0;
#endif
int slot, tos;
rnode = vm_radix_getroot(rtree);
if (rnode == NULL)
return (NULL);
else if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex <= index)
return (m);
else
return (NULL);
}
tos = 0;
for (;;) {
/*
* If the keys differ before the current bisection node,
* then the search key might rollback to the earliest
* available bisection node or to the largest key
* in the current node (if the owner is smaller than the
* search key).
*/
if (vm_radix_keybarr(rnode, index)) {
if (index > rnode->rn_owner) {
index = rnode->rn_owner + VM_RADIX_COUNT *
VM_RADIX_UNITLEVEL(rnode->rn_clev);
} else {
ascend:
KASSERT(++loops < 1000,
("vm_radix_lookup_le: too many loops"));
/*
* Pop nodes from the stack until either the
* stack is empty or a node that could have a
* matching descendant is found.
*/
do {
if (tos == 0)
return (NULL);
rnode = stack[--tos];
} while (vm_radix_slot(index,
rnode->rn_clev) == 0);
/*
* The following computation cannot overflow
* because index's slot at the current level
* is greater than 0.
*/
index = vm_radix_trimkey(index,
rnode->rn_clev);
}
index--;
KASSERT(!vm_radix_keybarr(rnode, index),
("vm_radix_lookup_le: keybarr failed"));
}
slot = vm_radix_slot(index, rnode->rn_clev);
child = rnode->rn_child[slot];
if (vm_radix_isleaf(child)) {
m = vm_radix_topage(child);
if (m->pindex <= index)
return (m);
} else if (child != NULL)
goto descend;
/*
* Look for an available edge or page within the current
* bisection node.
*/
if (slot > 0) {
inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
index |= inc - 1;
do {
index -= inc;
slot--;
child = rnode->rn_child[slot];
if (vm_radix_isleaf(child)) {
m = vm_radix_topage(child);
if (m->pindex <= index)
return (m);
} else if (child != NULL)
goto descend;
} while (slot > 0);
}
KASSERT(child == NULL || vm_radix_isleaf(child),
("vm_radix_lookup_le: child is radix node"));
/*
* If a page or edge smaller than the search slot is not found
* in the current node, ascend to the next higher-level node.
*/
goto ascend;
descend:
KASSERT(rnode->rn_clev > 0,
("vm_radix_lookup_le: pushing leaf's parent"));
KASSERT(tos < VM_RADIX_LIMIT,
("vm_radix_lookup_le: stack overflow"));
stack[tos++] = rnode;
rnode = child;
}
}
/*
* Remove the specified index from the tree.
* Panics if the key is not present.
*/
void
vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index)
{
struct vm_radix_node *rnode, *parent;
vm_page_t m;
int i, slot;
/*
* Detect if a page is going to be removed from a trie which is
* already undergoing another trie operation.
* Right now this is only possible for vm_radix_remove() recursing
* into vm_radix_insert().
* If this is the case, the caller must be notified about this
* situation. It will also takecare to update the RT_TRIE_MODIFIED
* accordingly.
* The RT_TRIE_MODIFIED bit is set here because the remove operation
* will always succeed.
*/
if ((rtree->rt_flags & RT_INSERT_INPROG) != 0)
rtree->rt_flags |= RT_TRIE_MODIFIED;
rnode = vm_radix_getroot(rtree);
if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex != index)
panic("%s: invalid key found", __func__);
vm_radix_setroot(rtree, NULL);
return;
}
parent = NULL;
for (;;) {
if (rnode == NULL)
panic("vm_radix_remove: impossible to locate the key");
slot = vm_radix_slot(index, rnode->rn_clev);
if (vm_radix_isleaf(rnode->rn_child[slot])) {
m = vm_radix_topage(rnode->rn_child[slot]);
if (m->pindex != index)
panic("%s: invalid key found", __func__);
rnode->rn_child[slot] = NULL;
rnode->rn_count--;
if (rnode->rn_count > 1)
break;
for (i = 0; i < VM_RADIX_COUNT; i++)
if (rnode->rn_child[i] != NULL)
break;
KASSERT(i != VM_RADIX_COUNT,
("%s: invalid node configuration", __func__));
if (parent == NULL)
vm_radix_setroot(rtree, rnode->rn_child[i]);
else {
slot = vm_radix_slot(index, parent->rn_clev);
KASSERT(parent->rn_child[slot] == rnode,
("%s: invalid child value", __func__));
parent->rn_child[slot] = rnode->rn_child[i];
}
rnode->rn_count--;
rnode->rn_child[i] = NULL;
vm_radix_node_put(rnode);
break;
}
parent = rnode;
rnode = rnode->rn_child[slot];
}
}
/*
* Remove and free all the nodes from the radix tree.
* This function is recursive but there is a tight control on it as the
* maximum depth of the tree is fixed.
*/
void
vm_radix_reclaim_allnodes(struct vm_radix *rtree)
{
struct vm_radix_node *root;
KASSERT((rtree->rt_flags & RT_INSERT_INPROG) == 0,
("vm_radix_reclaim_allnodes: unexpected trie recursion"));
root = vm_radix_getroot(rtree);
if (root == NULL)
return;
vm_radix_setroot(rtree, NULL);
if (!vm_radix_isleaf(root))
vm_radix_reclaim_allnodes_int(root);
}
/*
* Replace an existing page into the trie with another one.
* Panics if the replacing page is not present or if the new page has an
* invalid key.
*/
vm_page_t
vm_radix_replace(struct vm_radix *rtree, vm_page_t newpage, vm_pindex_t index)
{
struct vm_radix_node *rnode;
vm_page_t m;
int slot;
KASSERT(newpage->pindex == index, ("%s: newpage index invalid",
__func__));
rnode = vm_radix_getroot(rtree);
if (rnode == NULL)
panic("%s: replacing page on an empty trie", __func__);
if (vm_radix_isleaf(rnode)) {
m = vm_radix_topage(rnode);
if (m->pindex != index)
panic("%s: original replacing root key not found",
__func__);
rtree->rt_root = (uintptr_t)newpage | VM_RADIX_ISLEAF;
return (m);
}
for (;;) {
slot = vm_radix_slot(index, rnode->rn_clev);
if (vm_radix_isleaf(rnode->rn_child[slot])) {
m = vm_radix_topage(rnode->rn_child[slot]);
if (m->pindex == index) {
rnode->rn_child[slot] =
(void *)((uintptr_t)newpage |
VM_RADIX_ISLEAF);
return (m);
} else
break;
} else if (rnode->rn_child[slot] == NULL ||
vm_radix_keybarr(rnode->rn_child[slot], index))
break;
rnode = rnode->rn_child[slot];
}
panic("%s: original replacing page not found", __func__);
}
#ifdef DDB
/*
* Show details about the given radix node.
*/
DB_SHOW_COMMAND(radixnode, db_show_radixnode)
{
struct vm_radix_node *rnode;
int i;
if (!have_addr)
return;
rnode = (struct vm_radix_node *)addr;
db_printf("radixnode %p, owner %jx, children count %u, level %u:\n",
(void *)rnode, (uintmax_t)rnode->rn_owner, rnode->rn_count,
rnode->rn_clev);
for (i = 0; i < VM_RADIX_COUNT; i++)
if (rnode->rn_child[i] != NULL)
db_printf("slot: %d, val: %p, page: %p, clev: %d\n",
i, (void *)rnode->rn_child[i],
vm_radix_isleaf(rnode->rn_child[i]) ?
vm_radix_topage(rnode->rn_child[i]) : NULL,
rnode->rn_clev);
}
#endif /* DDB */