dentry: Add proper shrinking, LRU

Add proper shrinking, LRU, with some dentry fixes sprinkled around. Shrinkers aren't great atm, but they Work(tm) ish. Signed-off-by: Pedro Falcato <[email protected]>
heatd · Aug 4, 2024 · 6a40762 · 6a40762
1 parent 7cefbb0
commit 6a40762
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Showing 21 changed files with 564 additions and 61 deletions.
diff --git a/kernel/include/onyx/dentry.h b/kernel/include/onyx/dentry.h
@@ -16,6 +16,7 @@
 #include <onyx/inode.h>
 #include <onyx/limits.h>
 #include <onyx/list.h>
+#include <onyx/lru.h>
 #include <onyx/rcupdate.h>
 #include <onyx/rwlock.h>
 
@@ -32,6 +33,9 @@ __BEGIN_CDECLS
 #define DENTRY_FLAG_FAILED     (1 << 3)
 #define DENTRY_FLAG_NEGATIVE   (1 << 4)
 #define DENTRY_FLAG_HASHED     (1 << 5)
+#define DENTRY_FLAG_SHRINK     (1 << 6)
+#define DENTRY_FLAG_LRU        (1 << 7)
+#define DENTRY_FLAG_REFERENCED (1 << 8)
 
 struct dentry_operations
 {
@@ -56,7 +60,11 @@ struct dentry
     struct list_head d_cache_node;
     struct list_head d_children_head;
     const struct dentry_operations *d_ops;
-    struct rcu_head d_rcu;
+    union {
+        struct rcu_head d_rcu;
+        struct list_head d_lru;
+    };
+
     unsigned long d_private;
 #ifdef __cplusplus
     atomic<uint16_t> d_flags;
@@ -106,6 +114,22 @@ __always_inline bool dentry_is_symlink(const struct dentry *d)
     return S_ISLNK(d->d_inode->i_mode);
 }
 
+struct dcache_scan_result
+{
+    unsigned long scanned_bytes;
+    unsigned long scanned_objs;
+};
+
+struct dcache_shrink_result
+{
+    unsigned long to_shrink_bytes;
+    unsigned long to_shrink_objs;
+    struct list_head reclaim_list;
+};
+
+enum lru_walk_ret scan_dcache_lru_one(struct lru_list *lru, struct list_head *object, void *data);
+enum lru_walk_ret shrink_dcache_lru_one(struct lru_list *lru, struct list_head *object, void *data);
+
 __END_CDECLS
 
 #ifdef __cplusplus

diff --git a/kernel/include/onyx/list.h b/kernel/include/onyx/list.h
@@ -204,6 +204,20 @@ static inline void list_splice_tail(struct list_head *src, struct list_head *dst
         list_splice_internal(src, dst->prev, dst);
 }
 
+static inline int list_is_head(const struct list_head *list, const struct list_head *head)
+{
+    return list == head;
+}
+
+#define list_entry(ptr, type, member)         container_of(ptr, type, member)
+#define list_next_entry(pos, member)          list_entry((pos)->member.next, __typeof__(*(pos)), member)
+#define list_prepare_entry(pos, head, member) ((pos) ?: list_entry(head, __typeof__(*pos), member))
+#define list_entry_is_head(pos, head, member) list_is_head(&pos->member, (head))
+
+#define list_for_each_entry_continue(pos, head, member)                              \
+    for (pos = list_next_entry(pos, member); !list_entry_is_head(pos, head, member); \
+         pos = list_next_entry(pos, member))
+
 /*
  * TODO: This code is weird, inconsistent, and needs to be rewritten
  * and re-thought.

diff --git a/kernel/include/onyx/lru.h b/kernel/include/onyx/lru.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2024 Pedro Falcato
+ * This file is part of Onyx, and is released under the terms of the GPLv2 License
+ * check LICENSE at the root directory for more information
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ */
+
+#ifndef _ONYX_LRU_H
+#define _ONYX_LRU_H
+
+#include <onyx/list.h>
+#include <onyx/spinlock.h>
+
+/**
+ * @brief Simple LRU list implementation
+ *
+ */
+struct lru_list
+{
+    struct list_head obj_list;
+    struct spinlock lock;
+};
+
+__BEGIN_CDECLS
+
+static inline void lru_list_init(struct lru_list *lru)
+{
+    INIT_LIST_HEAD(&lru->obj_list);
+    spinlock_init(&lru->lock);
+}
+
+void lru_list_add(struct lru_list *lru, struct list_head *object);
+void lru_list_remove(struct lru_list *lru, struct list_head *object);
+
+enum lru_walk_ret
+{
+    LRU_WALK_ROTATE = 0,
+    LRU_WALK_SKIP,
+    LRU_WALK_STOP,
+    LRU_WALK_REMOVED,
+};
+
+void lru_list_walk(struct lru_list *lru,
+                   enum lru_walk_ret (*walk)(struct lru_list *lru, struct list_head *obj,
+                                             void *data),
+                   void *data);
+
+__END_CDECLS
+
+#endif
diff --git a/kernel/include/onyx/mm/shrinker.h b/kernel/include/onyx/mm/shrinker.h
@@ -10,6 +10,8 @@
 
 #include <onyx/list.h>
 
+__BEGIN_CDECLS
+
 struct shrink_control
 {
     /**
@@ -41,4 +43,6 @@ struct shrinker
 void shrinker_register(struct shrinker *shr);
 void shrinker_unregister(struct shrinker *shr);
 
+__END_CDECLS
+
 #endif
diff --git a/kernel/include/onyx/rcupdate.h b/kernel/include/onyx/rcupdate.h
@@ -26,6 +26,10 @@ void call_rcu(struct rcu_head *head, void (*callback)(struct rcu_head *head));
 void synchronize_rcu();
 void __kfree_rcu(struct rcu_head *head, unsigned long off);
 
+#ifdef __cplusplus
+#define _Static_assert(x) static_assert(x)
+#endif
+
 #define is_kfree_rcu_off(off) ((off) < 4096)
 #define kfree_rcu(ptr, head)                                                  \
     ({                                                                        \

diff --git a/kernel/include/onyx/seqlock.h b/kernel/include/onyx/seqlock.h
@@ -31,7 +31,21 @@ static inline unsigned int read_seqbegin(seqlock_t *sl)
 
 static inline bool read_seqretry(seqlock_t *sl, unsigned int old)
 {
-    return read_seqcount_retry(&sl->seqcount, old);
+    return !(old & 1) && read_seqcount_retry(&sl->seqcount, old);
+}
+
+static inline void read_seqbegin_or_lock(seqlock_t *sl, unsigned int *seq)
+{
+    if (unlikely(*seq & 1))
+        spin_lock(&sl->lock);
+    else
+        *seq = read_seqbegin(sl);
+}
+
+static inline void done_seqretry(seqlock_t *sl, unsigned int seq)
+{
+    if (unlikely(seq & 1))
+        spin_unlock(&sl->lock);
 }
 
 #endif
diff --git a/kernel/include/onyx/superblock.h b/kernel/include/onyx/superblock.h
@@ -12,6 +12,8 @@
 #include <sys/statfs.h>
 
 #include <onyx/list.h>
+#include <onyx/lru.h>
+#include <onyx/mm/shrinker.h>
 #include <onyx/mutex.h>
 #include <onyx/spinlock.h>
 #include <onyx/types.h>
@@ -37,6 +39,8 @@ struct superblock
     dev_t s_devnr;
     unsigned long s_flags;
     struct mutex s_rename_lock;
+    struct lru_list s_dcache_lru;
+    struct shrinker s_shrinker;
 };
 
 __BEGIN_CDECLS

diff --git a/kernel/kernel/Makefile b/kernel/kernel/Makefile
@@ -5,7 +5,7 @@ kern-y+= arc4random.o binfmt.o compression.o copy.o cppnew.o cpprt.o crc32.o dev
 	smp.o spinlock.o symbol.o tasklet.o time.o timer.o utils.o wait_queue.o \
 	worker.o cred.o list.o softirq.o cputime.o rlimit.o handle.o ctor.o internal_abi.o ssp.o \
 	cmdline.o syscall_thunk.o vdso.o sysinfo.o memstream.o perf.o radix.o rcupdate.o iovec_iter.o \
-	maple_tree.o bug.o
+	maple_tree.o bug.o lru.o
 
 kern-$(CONFIG_UBSAN)+= ubsan.o
 

diff --git a/kernel/kernel/fs/anon_inode.cpp b/kernel/kernel/fs/anon_inode.cpp
@@ -64,6 +64,7 @@ struct file *anon_inode_open(mode_t file_type, struct file_ops *ops, const char
     dentry = dentry_create(name, ino, nullptr);
     if (!dentry)
         goto err;
+    dget(dentry);
 
     f = inode_to_file(ino);
     if (!f)
@@ -73,7 +74,7 @@ struct file *anon_inode_open(mode_t file_type, struct file_ops *ops, const char
     return f;
 err:
     if (dentry)
-        dentry_put(dentry);
+        dput(dentry);
     if (ino)
         inode_unref(ino);
     return nullptr;