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Implement radix_tree_store() in the LinuxKPI for use with the coming

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extensible arrays implementation.

While at it add some more comments explaining the current
radix_tree_insert() function and make sure to clean the root node when
the radix tree reaches the maximum height. This can happen if the
index passed is too big when the tree is empty.

The radix_tree_store() function is basically a copy of the
radix_tree_insert() function with some added functionality.

The radix_tree_store() function is local to FreeBSD and does not yet
exist in Linux.

Reviewed by:		kib
MFC after:		1 week
Sponsored by:		Mellanox Technologies
This commit is contained in:
Hans Petter Selasky 2020-08-07 16:15:44 +00:00
parent 11412d5bc9
commit 6b839ff47b
2 changed files with 134 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
sys/compat/linuxkpi/common/include/linux/radix-tree.h
View File

@ -78,6 +78,7 @@ radix_tree_exception(void *arg)
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
int radix_tree_store(struct radix_tree_root *, unsigned long, void **);
bool radix_tree_iter_find(struct radix_tree_root *, struct radix_tree_iter *, void ***);
void radix_tree_iter_delete(struct radix_tree_root *, struct radix_tree_iter *, void **);

143
sys/compat/linuxkpi/common/src/linux_radix.c
View File

@ -2,7 +2,7 @@
* Copyright (c) 2010 Isilon Systems, Inc.
* Copyright (c) 2010 iX Systems, Inc.
* Copyright (c) 2010 Panasas, Inc.
* Copyright (c) 2013-2018 Mellanox Technologies, Ltd.
* Copyright (c) 2013-2020 Mellanox Technologies, Ltd.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -55,6 +55,17 @@ radix_pos(long id, int height)
return (id >> (RADIX_TREE_MAP_SHIFT * height)) & RADIX_TREE_MAP_MASK;
}
static void
radix_tree_clean_root_node(struct radix_tree_root *root)
{
/* Check if the root node should be freed */
if (root->rnode->count == 0) {
free(root->rnode, M_RADIX);
root->rnode = NULL;
root->height = 0;
}
}
void *
radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{
@ -197,8 +208,10 @@ radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *item)
while (radix_max(root) < index) {
/* check if the radix tree is getting too big */
if (root->height == RADIX_TREE_MAX_HEIGHT)
if (root->height == RADIX_TREE_MAX_HEIGHT) {
radix_tree_clean_root_node(root);
return (-E2BIG);
}
/*
* If the root radix level is not empty, we need to
@ -206,8 +219,16 @@ radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *item)
*/
if (node->count != 0) {
node = malloc(sizeof(*node), M_RADIX, root->gfp_mask | M_ZERO);
if (node == NULL)
if (node == NULL) {
/*
* Freeing the already allocated radix
* levels, if any, will be handled by
* the radix_tree_delete() function.
* This code path can only happen when
* the tree is not empty.
*/
return (-ENOMEM);
}
node->slots[0] = root->rnode;
node->count++;
root->rnode = node;
@ -231,14 +252,9 @@ radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *item)
temp[idx] = malloc(sizeof(*node), M_RADIX,
root->gfp_mask | M_ZERO);
if (temp[idx] == NULL) {
while(idx--)
while (idx--)
free(temp[idx], M_RADIX);
/* Check if we should free the root node as well. */
if (root->rnode->count == 0) {
free(root->rnode, M_RADIX);
root->rnode = NULL;
root->height = 0;
}
radix_tree_clean_root_node(root);
return (-ENOMEM);
}
}
@ -262,3 +278,110 @@ radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *item)
return (0);
}
int
radix_tree_store(struct radix_tree_root *root, unsigned long index, void **ppitem)
{
struct radix_tree_node *node;
struct radix_tree_node *temp[RADIX_TREE_MAX_HEIGHT - 1];
void *pitem;
int height;
int idx;
/*
* Inserting a NULL item means delete it. The old pointer is
* stored at the location pointed to by "ppitem".
*/
if (*ppitem == NULL) {
*ppitem = radix_tree_delete(root, index);
return (0);
}
/* get root node, if any */
node = root->rnode;
/* allocate root node, if any */
if (node == NULL) {
node = malloc(sizeof(*node), M_RADIX, root->gfp_mask | M_ZERO);
if (node == NULL)
return (-ENOMEM);
root->rnode = node;
root->height++;
}
/* expand radix tree as needed */
while (radix_max(root) < index) {
/* check if the radix tree is getting too big */
if (root->height == RADIX_TREE_MAX_HEIGHT) {
radix_tree_clean_root_node(root);
return (-E2BIG);
}
/*
* If the root radix level is not empty, we need to
* allocate a new radix level:
*/
if (node->count != 0) {
node = malloc(sizeof(*node), M_RADIX, root->gfp_mask | M_ZERO);
if (node == NULL) {
/*
* Freeing the already allocated radix
* levels, if any, will be handled by
* the radix_tree_delete() function.
* This code path can only happen when
* the tree is not empty.
*/
return (-ENOMEM);
}
node->slots[0] = root->rnode;
node->count++;
root->rnode = node;
}
root->height++;
}
/* get radix tree height index */
height = root->height - 1;
/* walk down the tree until the first missing node, if any */
for ( ; height != 0; height--) {
idx = radix_pos(index, height);
if (node->slots[idx] == NULL)
break;
node = node->slots[idx];
}
/* allocate the missing radix levels, if any */
for (idx = 0; idx != height; idx++) {
temp[idx] = malloc(sizeof(*node), M_RADIX,
root->gfp_mask | M_ZERO);
if (temp[idx] == NULL) {
while (idx--)
free(temp[idx], M_RADIX);
radix_tree_clean_root_node(root);
return (-ENOMEM);
}
}
/* setup new radix levels, if any */
for ( ; height != 0; height--) {
idx = radix_pos(index, height);
node->slots[idx] = temp[height - 1];
node->count++;
node = node->slots[idx];
}
/*
* Insert and adjust count if the item does not already exist.
*/
idx = radix_pos(index, 0);
/* swap */
pitem = node->slots[idx];
node->slots[idx] = *ppitem;
*ppitem = pitem;
if (pitem == NULL)
node->count++;
return (0);
}