--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mm.h>
+#include "lru_cache.h"
+#include "messages.h"
+
+/*
+ * Initialize a cache object.
+ *
+ * @cache: The cache.
+ * @max_size: Maximum size (number of entries) for the cache.
+ */
+void btrfs_lru_cache_init(struct btrfs_lru_cache *cache, unsigned int max_size)
+{
+ INIT_LIST_HEAD(&cache->lru_list);
+ mt_init(&cache->entries);
+ cache->size = 0;
+ cache->max_size = max_size;
+}
+
+/*
+ * Lookup for an entry in the cache.
+ *
+ * @cache: The cache.
+ * @key: The key of the entry we are looking for.
+ *
+ * Returns the entry associated with the key or NULL if none found.
+ */
+struct btrfs_lru_cache_entry *btrfs_lru_cache_lookup(struct btrfs_lru_cache *cache,
+ u64 key)
+{
+ struct btrfs_lru_cache_entry *entry;
+
+ entry = mtree_load(&cache->entries, key);
+ if (entry)
+ list_move_tail(&entry->lru_list, &cache->lru_list);
+
+ return entry;
+}
+
+/*
+ * Store an entry in the cache.
+ *
+ * @cache: The cache.
+ * @entry: The entry to store.
+ *
+ * Returns 0 on success and < 0 on error.
+ */
+int btrfs_lru_cache_store(struct btrfs_lru_cache *cache,
+ struct btrfs_lru_cache_entry *new_entry,
+ gfp_t gfp)
+{
+ int ret;
+
+ if (cache->size == cache->max_size) {
+ struct btrfs_lru_cache_entry *lru_entry;
+ struct btrfs_lru_cache_entry *mt_entry;
+
+ lru_entry = list_first_entry(&cache->lru_list,
+ struct btrfs_lru_cache_entry,
+ lru_list);
+ mt_entry = mtree_erase(&cache->entries, lru_entry->key);
+ ASSERT(mt_entry == lru_entry);
+ list_del(&mt_entry->lru_list);
+ kfree(mt_entry);
+ cache->size--;
+ }
+
+ ret = mtree_insert(&cache->entries, new_entry->key, new_entry, gfp);
+ if (ret < 0)
+ return ret;
+
+ list_add_tail(&new_entry->lru_list, &cache->lru_list);
+ cache->size++;
+
+ return 0;
+}
+
+/*
+ * Empty a cache.
+ *
+ * @cache: The cache to empty.
+ *
+ * Removes all entries from the cache.
+ */
+void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache)
+{
+ struct btrfs_lru_cache_entry *entry;
+ struct btrfs_lru_cache_entry *tmp;
+
+ list_for_each_entry_safe(entry, tmp, &cache->lru_list, lru_list)
+ kfree(entry);
+
+ INIT_LIST_HEAD(&cache->lru_list);
+ mtree_destroy(&cache->entries);
+ cache->size = 0;
+}
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_LRU_CACHE_H
+#define BTRFS_LRU_CACHE_H
+
+#include <linux/maple_tree.h>
+#include <linux/list.h>
+
+/*
+ * A cache entry. This is meant to be embedded in a structure of a user of
+ * this module. Similar to how struct list_head and struct rb_node are used.
+ *
+ * Note: it should be embedded as the first element in a struct (offset 0), and
+ * this module assumes it was allocated with kmalloc(), so it calls kfree() when
+ * it needs to free an entry.
+ */
+struct btrfs_lru_cache_entry {
+ struct list_head lru_list;
+ u64 key;
+};
+
+struct btrfs_lru_cache {
+ struct list_head lru_list;
+ struct maple_tree entries;
+ /* Number of entries stored in the cache. */
+ unsigned int size;
+ /* Maximum number of entries the cache can have. */
+ unsigned int max_size;
+};
+
+static inline unsigned int btrfs_lru_cache_size(const struct btrfs_lru_cache *cache)
+{
+ return cache->size;
+}
+
+void btrfs_lru_cache_init(struct btrfs_lru_cache *cache, unsigned int max_size);
+struct btrfs_lru_cache_entry *btrfs_lru_cache_lookup(struct btrfs_lru_cache *cache,
+ u64 key);
+int btrfs_lru_cache_store(struct btrfs_lru_cache *cache,
+ struct btrfs_lru_cache_entry *new_entry,
+ gfp_t gfp);
+void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache);
+
+#endif
#include "file-item.h"
#include "ioctl.h"
#include "verity.h"
+#include "lru_cache.h"
/*
* Maximum number of references an extent can have in order for us to attempt to
* x86_64).
*/
struct backref_cache_entry {
- /* List to link to the cache's lru list. */
- struct list_head list;
- /* The key for this entry in the cache. */
- u64 key;
+ struct btrfs_lru_cache_entry entry;
u64 root_ids[SEND_MAX_BACKREF_CACHE_ROOTS];
/* Number of valid elements in the root_ids array. */
int num_roots;
};
+/* See the comment at lru_cache.h about struct btrfs_lru_cache_entry. */
+static_assert(offsetof(struct backref_cache_entry, entry) == 0);
+
struct send_ctx {
struct file *send_filp;
loff_t send_off;
struct rb_root rbtree_new_refs;
struct rb_root rbtree_deleted_refs;
- struct {
- u64 last_reloc_trans;
- struct list_head lru_list;
- struct maple_tree entries;
- /* Number of entries stored in the cache. */
- int size;
- } backref_cache;
+ struct btrfs_lru_cache backref_cache;
+ u64 backref_cache_last_reloc_trans;
};
struct pending_dir_move {
return 0;
}
-static void empty_backref_cache(struct send_ctx *sctx)
-{
- struct backref_cache_entry *entry;
- struct backref_cache_entry *tmp;
-
- list_for_each_entry_safe(entry, tmp, &sctx->backref_cache.lru_list, list)
- kfree(entry);
-
- INIT_LIST_HEAD(&sctx->backref_cache.lru_list);
- mtree_destroy(&sctx->backref_cache.entries);
- sctx->backref_cache.size = 0;
-}
-
static bool lookup_backref_cache(u64 leaf_bytenr, void *ctx,
const u64 **root_ids_ret, int *root_count_ret)
{
struct send_ctx *sctx = bctx->sctx;
struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
const u64 key = leaf_bytenr >> fs_info->sectorsize_bits;
+ struct btrfs_lru_cache_entry *raw_entry;
struct backref_cache_entry *entry;
- if (sctx->backref_cache.size == 0)
+ if (btrfs_lru_cache_size(&sctx->backref_cache) == 0)
return false;
/*
* transaction handle or holding fs_info->commit_root_sem, so no need
* to take any lock here.
*/
- if (fs_info->last_reloc_trans > sctx->backref_cache.last_reloc_trans) {
- empty_backref_cache(sctx);
+ if (fs_info->last_reloc_trans > sctx->backref_cache_last_reloc_trans) {
+ btrfs_lru_cache_clear(&sctx->backref_cache);
return false;
}
- entry = mtree_load(&sctx->backref_cache.entries, key);
- if (!entry)
+ raw_entry = btrfs_lru_cache_lookup(&sctx->backref_cache, key);
+ if (!raw_entry)
return false;
+ entry = container_of(raw_entry, struct backref_cache_entry, entry);
*root_ids_ret = entry->root_ids;
*root_count_ret = entry->num_roots;
- list_move_tail(&entry->list, &sctx->backref_cache.lru_list);
return true;
}
if (!new_entry)
return;
- new_entry->key = leaf_bytenr >> fs_info->sectorsize_bits;
+ new_entry->entry.key = leaf_bytenr >> fs_info->sectorsize_bits;
new_entry->num_roots = 0;
ULIST_ITER_INIT(&uiter);
while ((node = ulist_next(root_ids, &uiter)) != NULL) {
* none of the roots is part of the list of roots from which we are
* allowed to clone. Cache the new entry as it's still useful to avoid
* backref walking to determine which roots have a path to the leaf.
+ *
+ * Also use GFP_NOFS because we're called while holding a transaction
+ * handle or while holding fs_info->commit_root_sem.
*/
-
- if (sctx->backref_cache.size >= SEND_MAX_BACKREF_CACHE_SIZE) {
- struct backref_cache_entry *lru_entry;
- struct backref_cache_entry *mt_entry;
-
- lru_entry = list_first_entry(&sctx->backref_cache.lru_list,
- struct backref_cache_entry, list);
- mt_entry = mtree_erase(&sctx->backref_cache.entries, lru_entry->key);
- ASSERT(mt_entry == lru_entry);
- list_del(&mt_entry->list);
- kfree(mt_entry);
- sctx->backref_cache.size--;
- }
-
- ret = mtree_insert(&sctx->backref_cache.entries, new_entry->key,
- new_entry, GFP_NOFS);
+ ret = btrfs_lru_cache_store(&sctx->backref_cache, &new_entry->entry,
+ GFP_NOFS);
ASSERT(ret == 0 || ret == -ENOMEM);
if (ret) {
/* Caching is optional, no worries. */
return;
}
- list_add_tail(&new_entry->list, &sctx->backref_cache.lru_list);
-
/*
* We are called from iterate_extent_inodes() while either holding a
* transaction handle or holding fs_info->commit_root_sem, so no need
* to take any lock here.
*/
- if (sctx->backref_cache.size == 0)
- sctx->backref_cache.last_reloc_trans = fs_info->last_reloc_trans;
-
- sctx->backref_cache.size++;
+ if (btrfs_lru_cache_size(&sctx->backref_cache) == 1)
+ sctx->backref_cache_last_reloc_trans = fs_info->last_reloc_trans;
}
static int check_extent_item(u64 bytenr, const struct btrfs_extent_item *ei,
INIT_RADIX_TREE(&sctx->name_cache, GFP_KERNEL);
INIT_LIST_HEAD(&sctx->name_cache_list);
- INIT_LIST_HEAD(&sctx->backref_cache.lru_list);
- mt_init(&sctx->backref_cache.entries);
+ btrfs_lru_cache_init(&sctx->backref_cache, SEND_MAX_BACKREF_CACHE_SIZE);
sctx->pending_dir_moves = RB_ROOT;
sctx->waiting_dir_moves = RB_ROOT;
close_current_inode(sctx);
- empty_backref_cache(sctx);
+ btrfs_lru_cache_clear(&sctx->backref_cache);
kfree(sctx);
}
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