f2fs: use kmem_cache pool during inline xattr lookups

It's been observed that kzalloc() on lookup_all_xattrs() are called millions
of times on Android, quickly becoming the top abuser of slub memory allocator.

Use a dedicated kmem cache pool for xattr lookups to mitigate this.
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -1487,6 +1487,9 @@ struct f2fs_sb_info {
 	__u32 s_chksum_seed;
 
 	struct workqueue_struct *post_read_wq;	/* post read workqueue */
+
+	struct kmem_cache *inline_xattr_slab;	/* inline xattr entry */
+	unsigned int inline_xattr_slab_size;	/* default inline xattr slab size */
 };
 
 struct f2fs_private_dio {

fs/f2fs/super.c

@@ -1202,6 +1202,7 @@ static void f2fs_put_super(struct super_block *sb)
 	kvfree(sbi->raw_super);
 
 	destroy_device_list(sbi);
+	f2fs_destroy_xattr_caches(sbi);
 	mempool_destroy(sbi->write_io_dummy);
 #ifdef CONFIG_QUOTA
 	for (i = 0; i < MAXQUOTAS; i++)
@@ -3458,12 +3459,17 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 		}
 	}
 
+	/* init per sbi slab cache */
+	err = f2fs_init_xattr_caches(sbi);
+	if (err)
+		goto free_io_dummy;
+
 	/* get an inode for meta space */
 	sbi->meta_inode = f2fs_iget(sb, F2FS_META_INO(sbi));
 	if (IS_ERR(sbi->meta_inode)) {
 		f2fs_err(sbi, "Failed to read F2FS meta data inode");
 		err = PTR_ERR(sbi->meta_inode);
-		goto free_io_dummy;
+		goto free_xattr_cache;
 	}
 
 	err = f2fs_get_valid_checkpoint(sbi);
@@ -3736,6 +3742,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	make_bad_inode(sbi->meta_inode);
 	iput(sbi->meta_inode);
 	sbi->meta_inode = NULL;
+free_xattr_cache:
+	f2fs_destroy_xattr_caches(sbi);
 free_io_dummy:
 	mempool_destroy(sbi->write_io_dummy);
 free_percpu:

fs/f2fs/xattr.c

@@ -23,6 +23,25 @@
 #include "xattr.h"
 #include "segment.h"
 
+static void *xattr_alloc(struct f2fs_sb_info *sbi, int size, bool *is_inline)
+{
+	if (likely(size == sbi->inline_xattr_slab_size)) {
+		*is_inline = true;
+		return kmem_cache_zalloc(sbi->inline_xattr_slab, GFP_NOFS);
+	}
+	*is_inline = false;
+	return f2fs_kzalloc(sbi, size, GFP_NOFS);
+}
+
+static void xattr_free(struct f2fs_sb_info *sbi, void *xattr_addr,
+							bool is_inline)
+{
+	if (is_inline)
+		kmem_cache_free(sbi->inline_xattr_slab, xattr_addr);
+	else
+		kvfree(xattr_addr);
+}
+
 static int f2fs_xattr_generic_get(const struct xattr_handler *handler,
 		struct dentry *unused, struct inode *inode,
 		const char *name, void *buffer, size_t size)
@@ -301,7 +320,8 @@ static int read_xattr_block(struct inode *inode, void *txattr_addr)
 static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
 				unsigned int index, unsigned int len,
 				const char *name, struct f2fs_xattr_entry **xe,
-				void **base_addr, int *base_size)
+				void **base_addr, int *base_size,
+				bool *is_inline)
 {
 	void *cur_addr, *txattr_addr, *last_txattr_addr;
 	void *last_addr = NULL;
@@ -313,7 +333,7 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
 		return -ENODATA;
 
 	*base_size = XATTR_SIZE(inode) + XATTR_PADDING_SIZE;
-	txattr_addr = f2fs_kzalloc(F2FS_I_SB(inode), *base_size, GFP_NOFS);
+	txattr_addr = xattr_alloc(F2FS_I_SB(inode), *base_size, is_inline);
 	if (!txattr_addr)
 		return -ENOMEM;
 
@@ -362,7 +382,7 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
 	*base_addr = txattr_addr;
 	return 0;
 out:
-	kvfree(txattr_addr);
+	xattr_free(F2FS_I_SB(inode), txattr_addr, *is_inline);
 	return err;
 }
 
@@ -499,6 +519,7 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
 	unsigned int size, len;
 	void *base_addr = NULL;
 	int base_size;
+	bool is_inline;
 
 	if (name == NULL)
 		return -EINVAL;
@@ -509,7 +530,7 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
 
 	down_read(&F2FS_I(inode)->i_xattr_sem);
 	error = lookup_all_xattrs(inode, ipage, index, len, name,
-				&entry, &base_addr, &base_size);
+				&entry, &base_addr, &base_size, &is_inline);
 	up_read(&F2FS_I(inode)->i_xattr_sem);
 	if (error)
 		return error;
@@ -532,7 +553,7 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
 	}
 	error = size;
 out:
-	kvfree(base_addr);
+	xattr_free(F2FS_I_SB(inode), base_addr, is_inline);
 	return error;
 }
 
@@ -764,3 +785,26 @@ int f2fs_setxattr(struct inode *inode, int index, const char *name,
 	f2fs_update_time(sbi, REQ_TIME);
 	return err;
 }
+
+int f2fs_init_xattr_caches(struct f2fs_sb_info *sbi)
+{
+	dev_t dev = sbi->sb->s_bdev->bd_dev;
+	char slab_name[32];
+
+	sprintf(slab_name, "f2fs_xattr_entry-%u:%u", MAJOR(dev), MINOR(dev));
+
+	sbi->inline_xattr_slab_size = F2FS_OPTION(sbi).inline_xattr_size *
+					sizeof(__le32) + XATTR_PADDING_SIZE;
+
+	sbi->inline_xattr_slab = f2fs_kmem_cache_create(slab_name,
+					sbi->inline_xattr_slab_size);
+	if (!sbi->inline_xattr_slab)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void f2fs_destroy_xattr_caches(struct f2fs_sb_info *sbi)
+{
+	kmem_cache_destroy(sbi->inline_xattr_slab);
+}

fs/f2fs/xattr.h

@@ -131,6 +131,8 @@ extern int f2fs_setxattr(struct inode *, int, const char *,
 extern int f2fs_getxattr(struct inode *, int, const char *, void *,
 						size_t, struct page *);
 extern ssize_t f2fs_listxattr(struct dentry *, char *, size_t);
+extern int f2fs_init_xattr_caches(struct f2fs_sb_info *);
+extern void f2fs_destroy_xattr_caches(struct f2fs_sb_info *);
 #else
 
 #define f2fs_xattr_handlers	NULL
@@ -151,6 +153,8 @@ static inline ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
 {
 	return -EOPNOTSUPP;
 }
+static int f2fs_init_xattr_caches(struct f2fs_sb_info *sbi) { return 0; }
+static void f2fs_destroy_xattr_caches(struct f2fs_sb_info *sbi) { }
 #endif
 
 #ifdef CONFIG_F2FS_FS_SECURITY