[PATCH 1/2] mm: zswap.c: add xarray tree to zswap
From: Chris Li
Date: Wed Jan 17 2024 - 22:06:20 EST
The xarray tree is added alongside the zswap RB tree.
Checks for the xarray get the same result as the RB tree operations.
Rename the zswap RB tree function to a more generic function
name without the RB part.
---
mm/zswap.c | 60 ++++++++++++++++++++++++++++++++++++++++++------------------
1 file changed, 42 insertions(+), 18 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index f8bc9e089268..a40b0076722b 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -235,6 +235,7 @@ struct zswap_entry {
*/
struct zswap_tree {
struct rb_root rbroot;
+ struct xarray xarray;
spinlock_t lock;
};
@@ -462,9 +463,9 @@ static void zswap_lru_putback(struct list_lru *list_lru,
/*********************************
* rbtree functions
**********************************/
-static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
+static struct zswap_entry *zswap_search(struct zswap_tree *tree, pgoff_t offset)
{
- struct rb_node *node = root->rb_node;
+ struct rb_node *node = tree->rbroot.rb_node;
struct zswap_entry *entry;
pgoff_t entry_offset;
@@ -475,8 +476,12 @@ static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
node = node->rb_left;
else if (entry_offset < offset)
node = node->rb_right;
- else
+ else {
+ struct zswap_entry *e = xa_load(&tree->xarray, offset);
+
+ BUG_ON(entry != e);
return entry;
+ }
}
return NULL;
}
@@ -485,13 +490,15 @@ static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
* In the case that a entry with the same offset is found, a pointer to
* the existing entry is stored in dupentry and the function returns -EEXIST
*/
-static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
+static int zswap_insert(struct zswap_tree *tree, struct zswap_entry *entry,
struct zswap_entry **dupentry)
{
+ struct rb_root *root = &tree->rbroot;
struct rb_node **link = &root->rb_node, *parent = NULL;
- struct zswap_entry *myentry;
+ struct zswap_entry *myentry, *old;
pgoff_t myentry_offset, entry_offset = swp_offset(entry->swpentry);
+
while (*link) {
parent = *link;
myentry = rb_entry(parent, struct zswap_entry, rbnode);
@@ -501,19 +508,26 @@ static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
else if (myentry_offset < entry_offset)
link = &(*link)->rb_right;
else {
+ old = xa_load(&tree->xarray, entry_offset);
+ BUG_ON(old != myentry);
*dupentry = myentry;
return -EEXIST;
}
}
rb_link_node(&entry->rbnode, parent, link);
rb_insert_color(&entry->rbnode, root);
+ old = xa_store(&tree->xarray, entry_offset, entry, GFP_KERNEL);
return 0;
}
-static bool zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
+static bool zswap_erase(struct zswap_tree *tree, struct zswap_entry *entry)
{
+ pgoff_t offset = swp_offset(entry->swpentry);
if (!RB_EMPTY_NODE(&entry->rbnode)) {
- rb_erase(&entry->rbnode, root);
+ struct zswap_entry *old;
+ old = xa_erase(&tree->xarray, offset);
+ BUG_ON(old != entry);
+ rb_erase(&entry->rbnode, &tree->rbroot);
RB_CLEAR_NODE(&entry->rbnode);
return true;
}
@@ -575,12 +589,12 @@ static void zswap_entry_put(struct zswap_tree *tree,
}
/* caller must hold the tree lock */
-static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
+static struct zswap_entry *zswap_entry_find_get(struct zswap_tree *tree,
pgoff_t offset)
{
struct zswap_entry *entry;
- entry = zswap_rb_search(root, offset);
+ entry = zswap_search(tree, offset);
if (entry)
zswap_entry_get(entry);
@@ -845,7 +859,7 @@ static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
static void zswap_invalidate_entry(struct zswap_tree *tree,
struct zswap_entry *entry)
{
- if (zswap_rb_erase(&tree->rbroot, entry))
+ if (zswap_erase(tree, entry))
zswap_entry_put(tree, entry);
}
@@ -875,7 +889,7 @@ static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_o
/* Check for invalidate() race */
spin_lock(&tree->lock);
- if (entry != zswap_rb_search(&tree->rbroot, swpoffset))
+ if (entry != zswap_search(tree, swpoffset))
goto unlock;
/* Hold a reference to prevent a free during writeback */
@@ -1407,6 +1421,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
struct zswap_tree *tree)
{
swp_entry_t swpentry = entry->swpentry;
+ pgoff_t offset = swp_offset(swpentry);
+ struct zswap_entry *e;
struct folio *folio;
struct mempolicy *mpol;
bool folio_was_allocated;
@@ -1439,7 +1455,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
* avoid overwriting a new swap folio with old compressed data.
*/
spin_lock(&tree->lock);
- if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) {
+ e = zswap_search(tree, offset);
+ if (e != entry) {
spin_unlock(&tree->lock);
delete_from_swap_cache(folio);
return -ENOMEM;
@@ -1528,7 +1545,7 @@ bool zswap_store(struct folio *folio)
* the tree, and it might be written back overriding the new data.
*/
spin_lock(&tree->lock);
- dupentry = zswap_rb_search(&tree->rbroot, offset);
+ dupentry = zswap_search(tree, offset);
if (dupentry) {
zswap_duplicate_entry++;
zswap_invalidate_entry(tree, dupentry);
@@ -1671,7 +1688,7 @@ bool zswap_store(struct folio *folio)
* found again here it means that something went wrong in the swap
* cache.
*/
- while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) {
+ while (zswap_insert(tree, entry, &dupentry) == -EEXIST) {
WARN_ON(1);
zswap_duplicate_entry++;
zswap_invalidate_entry(tree, dupentry);
@@ -1722,7 +1739,7 @@ bool zswap_load(struct folio *folio)
/* find */
spin_lock(&tree->lock);
- entry = zswap_entry_find_get(&tree->rbroot, offset);
+ entry = zswap_entry_find_get(tree, offset);
if (!entry) {
spin_unlock(&tree->lock);
return false;
@@ -1762,7 +1779,7 @@ void zswap_invalidate(int type, pgoff_t offset)
/* find */
spin_lock(&tree->lock);
- entry = zswap_rb_search(&tree->rbroot, offset);
+ entry = zswap_search(tree, offset);
if (!entry) {
/* entry was written back */
spin_unlock(&tree->lock);
@@ -1783,6 +1800,7 @@ void zswap_swapon(int type)
}
tree->rbroot = RB_ROOT;
+ xa_init(&tree->xarray);
spin_lock_init(&tree->lock);
zswap_trees[type] = tree;
}
@@ -1790,15 +1808,21 @@ void zswap_swapon(int type)
void zswap_swapoff(int type)
{
struct zswap_tree *tree = zswap_trees[type];
- struct zswap_entry *entry, *n;
+ struct zswap_entry *entry, *e, *n;
+ XA_STATE(xas, tree ? &tree->xarray : NULL, 0);
if (!tree)
return;
/* walk the tree and free everything */
spin_lock(&tree->lock);
+
+ xas_for_each(&xas, e, ULONG_MAX)
+ zswap_invalidate_entry(tree, e);
+
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
- zswap_free_entry(entry);
+ BUG_ON(entry);
+
tree->rbroot = RB_ROOT;
spin_unlock(&tree->lock);
kfree(tree);
--
2.43.0.429.g432eaa2c6b-goog