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From: Chengguang Xu <cgxu519@gmx.com>
To: linux-unionfs@vger.kernel.org
Cc: miklos@szeredi.hu, amir73il@gmail.com, Chengguang Xu <cgxu519@gmx.com>
Subject: [PATCH 3/3] ovl: introduce a dedicated cache pool for ovl_entry
Date: Tue, 17 Apr 2018 10:42:45 +0800	[thread overview]
Message-ID: <1523932965-25792-3-git-send-email-cgxu519@gmx.com> (raw)
In-Reply-To: <1523932965-25792-1-git-send-email-cgxu519@gmx.com>

Introduce a dedicated cache pool for ovl_entry to optimize
memory allocation adn deallocation.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
---
 fs/overlayfs/export.c    | 11 +++++++----
 fs/overlayfs/namei.c     |  7 +++++--
 fs/overlayfs/overlayfs.h |  4 ++++
 fs/overlayfs/ovl_entry.h |  9 +++++----
 fs/overlayfs/super.c     | 38 +++++++++++++++++++++++++++++---------
 fs/overlayfs/util.c      | 28 ++++++++++++++++++++++++----
 6 files changed, 74 insertions(+), 23 deletions(-)

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index f2ba5fb..b1047ae 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -321,8 +321,8 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
 			goto nomem;
 
 		if (lower) {
-			oe->lowerstack->dentry = dget(lower);
-			oe->lowerstack->layer = lowerpath->layer;
+			oe->lowerstack.dentry = dget(lower);
+			oe->lowerstack.layer = lowerpath->layer;
 		}
 		dentry->d_fsdata = oe;
 		if (upper_alias)
@@ -346,9 +346,12 @@ static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
 	if (!idx)
 		return ovl_dentry_upper(dentry);
 
+	if (oe->numlower == 1 && oe->lowerstack.layer->idx == idx)
+		return oe->lowerstack.dentry;
+
 	for (i = 0; i < oe->numlower; i++) {
-		if (oe->lowerstack[i].layer->idx == idx)
-			return oe->lowerstack[i].dentry;
+		if (oe->lowerstacks[i].layer->idx == idx)
+			return oe->lowerstacks[i].dentry;
 	}
 
 	return NULL;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index eb3ec6c..51fd914 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -994,7 +994,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	if (!oe)
 		goto out_put;
 
-	memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
+	if (oe->numlower == 1)
+		memcpy(&oe->lowerstack, stack, sizeof(struct ovl_path));
+	else
+		memcpy(oe->lowerstacks, stack, sizeof(struct ovl_path) * ctr);
 	dentry->d_fsdata = oe;
 
 	if (upperopaque)
@@ -1028,7 +1031,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 
 out_free_oe:
 	dentry->d_fsdata = NULL;
-	kfree(oe);
+	ovl_free_entry(oe);
 out_put:
 	dput(index);
 	for (i = 0; i < ctr; i++)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 8039602..a104e02 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -207,6 +207,7 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
 bool ovl_index_all(struct super_block *sb);
 bool ovl_verify_lower(struct super_block *sb);
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
+void ovl_free_entry(struct ovl_entry *oe);
 bool ovl_dentry_remote(struct dentry *dentry);
 bool ovl_dentry_weird(struct dentry *dentry);
 enum ovl_path_type ovl_path_type(struct dentry *dentry);
@@ -378,3 +379,6 @@ int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 
 /* export.c */
 extern const struct export_operations ovl_export_operations;
+
+/* super.c */
+extern struct kmem_cache *ovl_entry_cachep;
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 41655a7..3ed8ab4 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -71,13 +71,14 @@ struct ovl_fs {
 /* private information held for every overlayfs dentry */
 struct ovl_entry {
 	union {
-		struct {
-			unsigned long flags;
-		};
+		unsigned long flags;
 		struct rcu_head rcu;
 	};
 	unsigned numlower;
-	struct ovl_path lowerstack[];
+	union {
+		struct ovl_path lowerstack;
+		struct ovl_path *lowerstacks;
+	};
 };
 
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 38c1dd1..6327497 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -60,8 +60,11 @@ static void ovl_entry_stack_free(struct ovl_entry *oe)
 {
 	unsigned int i;
 
-	for (i = 0; i < oe->numlower; i++)
-		dput(oe->lowerstack[i].dentry);
+	if (oe->numlower == 1)
+		dput(oe->lowerstack.dentry);
+	else
+		for (i = 0; i < oe->numlower; i++)
+			dput(oe->lowerstacks[i].dentry);
 }
 
 static void ovl_dentry_release(struct dentry *dentry)
@@ -191,6 +194,7 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
 };
 
 static struct kmem_cache *ovl_inode_cachep;
+struct kmem_cache *ovl_entry_cachep;
 
 static struct inode *ovl_alloc_inode(struct super_block *sb)
 {
@@ -1332,9 +1336,14 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
 	if (!oe)
 		goto out_err;
 
-	for (i = 0; i < numlower; i++) {
-		oe->lowerstack[i].dentry = dget(stack[i].dentry);
-		oe->lowerstack[i].layer = &ofs->lower_layers[i];
+	if (numlower == 1) {
+		oe->lowerstack.dentry = stack[0].dentry;
+		oe->lowerstack.layer = &ofs->lower_layers[0];
+	} else {
+		for (i = 0; i < numlower; i++) {
+			oe->lowerstacks[i].dentry = dget(stack[i].dentry);
+			oe->lowerstacks[i].layer = &ofs->lower_layers[i];
+		}
 	}
 
 	if (remote)
@@ -1515,20 +1524,31 @@ static void ovl_inode_init_once(void *foo)
 
 static int __init ovl_init(void)
 {
-	int err;
+	int err = -ENOMEM;
 
 	ovl_inode_cachep = kmem_cache_create("ovl_inode",
 					     sizeof(struct ovl_inode), 0,
 					     (SLAB_RECLAIM_ACCOUNT|
 					      SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 					     ovl_inode_init_once);
-	if (ovl_inode_cachep == NULL)
-		return -ENOMEM;
+	if (!ovl_inode_cachep)
+		return err;
+
+	ovl_entry_cachep = KMEM_CACHE(ovl_entry,
+				SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
+	if (!ovl_entry_cachep)
+		goto bad_entry_cachep;
 
 	err = register_filesystem(&ovl_fs_type);
 	if (err)
-		kmem_cache_destroy(ovl_inode_cachep);
+		goto err_out;
 
+	return 0;
+
+err_out:
+	kmem_cache_destroy(ovl_entry_cachep);
+bad_entry_cachep:
+	kmem_cache_destroy(ovl_inode_cachep);
 	return err;
 }
 
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index a3459e6..7d4ff3e 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -95,13 +95,30 @@ bool ovl_verify_lower(struct super_block *sb)
 	return ofs->config.nfs_export && ofs->config.index;
 }
 
+void ovl_free_entry(struct ovl_entry *oe)
+{
+	if (oe->numlower > 1)
+		kfree(oe->lowerstacks);
+
+	kmem_cache_free(ovl_entry_cachep, oe);
+}
+
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
-	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
-	struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+	size_t size = sizeof(struct ovl_path) * numlower;
+	struct ovl_entry *oe;
 
-	if (oe)
+	oe = kmem_cache_zalloc(ovl_entry_cachep, GFP_KERNEL);
+	if (oe) {
 		oe->numlower = numlower;
+		if (numlower > 1) {
+			oe->lowerstacks = kzalloc(size, GFP_KERNEL);
+			if (!oe->lowerstacks) {
+				kmem_cache_free(ovl_entry_cachep, oe);
+				oe = NULL;
+			}
+		}
+	}
 
 	return oe;
 }
@@ -186,7 +203,10 @@ struct ovl_path *__ovl_path_lower(struct ovl_entry *oe, int layer)
 	if (layer > oe->numlower)
 		return NULL;
 
-	return &oe->lowerstack[layer - 1];
+	if (layer == 1 && oe->numlower == 1)
+		return &oe->lowerstack;
+	else
+		return &oe->lowerstacks[layer - 1];
 }
 
 struct vfsmount *ovl_mnt_lower(struct dentry *dentry)
-- 
1.8.3.1

  parent reply	other threads:[~2018-04-17  2:42 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  2:42 [PATCH 1/3] ovl: refactor lowerstack related functions Chengguang Xu
2018-04-17  2:42 ` [PATCH 2/3] ovl: using lowestack handling functions to replace bare array operation Chengguang Xu
2018-04-17 11:16   ` Amir Goldstein
2018-04-18  3:42     ` cgxu519
2018-04-17  2:42 ` Chengguang Xu [this message]
2018-04-17 10:41   ` [PATCH 3/3] ovl: introduce a dedicated cache pool for ovl_entry Amir Goldstein
2018-04-18  0:59     ` cgxu519
2018-04-17 11:04 ` [PATCH 1/3] ovl: refactor lowerstack related functions Amir Goldstein

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