KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 299 insertions, 0 deletions

diff --git a/fs/jffs2/malloc.c b/fs/jffs2/malloc.c
new file mode 100644
index 000000000..411de8b36
--- /dev/null
+++ b/fs/jffs2/malloc.c
@@ -0,0 +1,299 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/jffs2.h>
+#include "nodelist.h"
+
+/* These are initialised to NULL in the kernel startup code.
+   If you're porting to other operating systems, beware */
+static struct kmem_cache *full_dnode_slab;
+static struct kmem_cache *raw_dirent_slab;
+static struct kmem_cache *raw_inode_slab;
+static struct kmem_cache *tmp_dnode_info_slab;
+static struct kmem_cache *raw_node_ref_slab;
+static struct kmem_cache *node_frag_slab;
+static struct kmem_cache *inode_cache_slab;
+#ifdef CONFIG_JFFS2_FS_XATTR
+static struct kmem_cache *xattr_datum_cache;
+static struct kmem_cache *xattr_ref_cache;
+#endif
+
+int __init jffs2_create_slab_caches(void)
+{
+	full_dnode_slab = KMEM_CACHE(jffs2_full_dnode, 0);
+	if (!full_dnode_slab)
+		goto err;
+
+	raw_dirent_slab = KMEM_CACHE(jffs2_raw_dirent, SLAB_HWCACHE_ALIGN);
+	if (!raw_dirent_slab)
+		goto err;
+
+	raw_inode_slab = KMEM_CACHE(jffs2_raw_inode, SLAB_HWCACHE_ALIGN);
+	if (!raw_inode_slab)
+		goto err;
+
+	tmp_dnode_info_slab = KMEM_CACHE(jffs2_tmp_dnode_info, 0);
+	if (!tmp_dnode_info_slab)
+		goto err;
+
+	raw_node_ref_slab = kmem_cache_create("jffs2_refblock",
+					      sizeof(struct jffs2_raw_node_ref) * (REFS_PER_BLOCK + 1),
+					      0, 0, NULL);
+	if (!raw_node_ref_slab)
+		goto err;
+
+	node_frag_slab = KMEM_CACHE(jffs2_node_frag, 0);
+	if (!node_frag_slab)
+		goto err;
+
+	inode_cache_slab = KMEM_CACHE(jffs2_inode_cache, 0);
+	if (!inode_cache_slab)
+		goto err;
+
+#ifdef CONFIG_JFFS2_FS_XATTR
+	xattr_datum_cache = KMEM_CACHE(jffs2_xattr_datum, 0);
+	if (!xattr_datum_cache)
+		goto err;
+
+	xattr_ref_cache = KMEM_CACHE(jffs2_xattr_ref, 0);
+	if (!xattr_ref_cache)
+		goto err;
+#endif
+
+	return 0;
+ err:
+	jffs2_destroy_slab_caches();
+	return -ENOMEM;
+}
+
+void jffs2_destroy_slab_caches(void)
+{
+	kmem_cache_destroy(full_dnode_slab);
+	kmem_cache_destroy(raw_dirent_slab);
+	kmem_cache_destroy(raw_inode_slab);
+	kmem_cache_destroy(tmp_dnode_info_slab);
+	kmem_cache_destroy(raw_node_ref_slab);
+	kmem_cache_destroy(node_frag_slab);
+	kmem_cache_destroy(inode_cache_slab);
+#ifdef CONFIG_JFFS2_FS_XATTR
+	kmem_cache_destroy(xattr_datum_cache);
+	kmem_cache_destroy(xattr_ref_cache);
+#endif
+}
+
+struct jffs2_full_dirent *jffs2_alloc_full_dirent(int namesize)
+{
+	struct jffs2_full_dirent *ret;
+	ret = kmalloc(sizeof(struct jffs2_full_dirent) + namesize, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_full_dirent(struct jffs2_full_dirent *x)
+{
+	dbg_memalloc("%p\n", x);
+	kfree(x);
+}
+
+struct jffs2_full_dnode *jffs2_alloc_full_dnode(void)
+{
+	struct jffs2_full_dnode *ret;
+	ret = kmem_cache_alloc(full_dnode_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_full_dnode(struct jffs2_full_dnode *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(full_dnode_slab, x);
+}
+
+struct jffs2_raw_dirent *jffs2_alloc_raw_dirent(void)
+{
+	struct jffs2_raw_dirent *ret;
+	ret = kmem_cache_alloc(raw_dirent_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_raw_dirent(struct jffs2_raw_dirent *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(raw_dirent_slab, x);
+}
+
+struct jffs2_raw_inode *jffs2_alloc_raw_inode(void)
+{
+	struct jffs2_raw_inode *ret;
+	ret = kmem_cache_alloc(raw_inode_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_raw_inode(struct jffs2_raw_inode *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(raw_inode_slab, x);
+}
+
+struct jffs2_tmp_dnode_info *jffs2_alloc_tmp_dnode_info(void)
+{
+	struct jffs2_tmp_dnode_info *ret;
+	ret = kmem_cache_alloc(tmp_dnode_info_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n",
+		ret);
+	return ret;
+}
+
+void jffs2_free_tmp_dnode_info(struct jffs2_tmp_dnode_info *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(tmp_dnode_info_slab, x);
+}
+
+static struct jffs2_raw_node_ref *jffs2_alloc_refblock(void)
+{
+	struct jffs2_raw_node_ref *ret;
+
+	ret = kmem_cache_alloc(raw_node_ref_slab, GFP_KERNEL);
+	if (ret) {
+		int i = 0;
+		for (i=0; i < REFS_PER_BLOCK; i++) {
+			ret[i].flash_offset = REF_EMPTY_NODE;
+			ret[i].next_in_ino = NULL;
+		}
+		ret[i].flash_offset = REF_LINK_NODE;
+		ret[i].next_in_ino = NULL;
+	}
+	return ret;
+}
+
+int jffs2_prealloc_raw_node_refs(struct jffs2_sb_info *c,
+				 struct jffs2_eraseblock *jeb, int nr)
+{
+	struct jffs2_raw_node_ref **p, *ref;
+	int i = nr;
+
+	dbg_memalloc("%d\n", nr);
+
+	p = &jeb->last_node;
+	ref = *p;
+
+	dbg_memalloc("Reserving %d refs for block @0x%08x\n", nr, jeb->offset);
+
+	/* If jeb->last_node is really a valid node then skip over it */
+	if (ref && ref->flash_offset != REF_EMPTY_NODE)
+		ref++;
+
+	while (i) {
+		if (!ref) {
+			dbg_memalloc("Allocating new refblock linked from %p\n", p);
+			ref = *p = jffs2_alloc_refblock();
+			if (!ref)
+				return -ENOMEM;
+		}
+		if (ref->flash_offset == REF_LINK_NODE) {
+			p = &ref->next_in_ino;
+			ref = *p;
+			continue;
+		}
+		i--;
+		ref++;
+	}
+	jeb->allocated_refs = nr;
+
+	dbg_memalloc("Reserved %d refs for block @0x%08x, last_node is %p (%08x,%p)\n",
+		  nr, jeb->offset, jeb->last_node, jeb->last_node->flash_offset,
+		  jeb->last_node->next_in_ino);
+
+	return 0;
+}
+
+void jffs2_free_refblock(struct jffs2_raw_node_ref *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(raw_node_ref_slab, x);
+}
+
+struct jffs2_node_frag *jffs2_alloc_node_frag(void)
+{
+	struct jffs2_node_frag *ret;
+	ret = kmem_cache_alloc(node_frag_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_node_frag(struct jffs2_node_frag *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(node_frag_slab, x);
+}
+
+struct jffs2_inode_cache *jffs2_alloc_inode_cache(void)
+{
+	struct jffs2_inode_cache *ret;
+	ret = kmem_cache_alloc(inode_cache_slab, GFP_KERNEL);
+	dbg_memalloc("%p\n", ret);
+	return ret;
+}
+
+void jffs2_free_inode_cache(struct jffs2_inode_cache *x)
+{
+	dbg_memalloc("%p\n", x);
+	kmem_cache_free(inode_cache_slab, x);
+}
+
+#ifdef CONFIG_JFFS2_FS_XATTR
+struct jffs2_xattr_datum *jffs2_alloc_xattr_datum(void)
+{
+	struct jffs2_xattr_datum *xd;
+	xd = kmem_cache_zalloc(xattr_datum_cache, GFP_KERNEL);
+	dbg_memalloc("%p\n", xd);
+	if (!xd)
+		return NULL;
+
+	xd->class = RAWNODE_CLASS_XATTR_DATUM;
+	xd->node = (void *)xd;
+	INIT_LIST_HEAD(&xd->xindex);
+	return xd;
+}
+
+void jffs2_free_xattr_datum(struct jffs2_xattr_datum *xd)
+{
+	dbg_memalloc("%p\n", xd);
+	kmem_cache_free(xattr_datum_cache, xd);
+}
+
+struct jffs2_xattr_ref *jffs2_alloc_xattr_ref(void)
+{
+	struct jffs2_xattr_ref *ref;
+	ref = kmem_cache_zalloc(xattr_ref_cache, GFP_KERNEL);
+	dbg_memalloc("%p\n", ref);
+	if (!ref)
+		return NULL;
+
+	ref->class = RAWNODE_CLASS_XATTR_REF;
+	ref->node = (void *)ref;
+	return ref;
+}
+
+void jffs2_free_xattr_ref(struct jffs2_xattr_ref *ref)
+{
+	dbg_memalloc("%p\n", ref);
+	kmem_cache_free(xattr_ref_cache, ref);
+}
+#endif