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Subject[PATCH 16/25] staging: erofs: add erofs_allocpage
Date
This patch introduces an temporary _on-stack_ page
pool to reuse the freed page directly as much as
it can for better performance and release all pages
at a time, it also slightly reduces the possibility of
the potential memory allocation failure.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/Makefile | 2 +-
drivers/staging/erofs/internal.h | 7 +++++++
drivers/staging/erofs/utils.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 39 insertions(+), 1 deletion(-)
create mode 100644 drivers/staging/erofs/utils.c

diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
index 8558c76..490fa6c 100644
--- a/drivers/staging/erofs/Makefile
+++ b/drivers/staging/erofs/Makefile
@@ -7,7 +7,7 @@ ccflags-y += -Wall -DEROFS_VERSION=\"$(EROFS_VERSION)\"
obj-$(CONFIG_EROFS_FS) += erofs.o
# staging requirement: to be self-contained in its own directory
ccflags-y += -I$(src)/include
-erofs-objs := super.o inode.o data.o namei.o dir.o
+erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index bea5ec4..210ab6c 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -369,5 +369,12 @@ static inline void erofs_vunmap(const void *mem, unsigned int count)
#endif
}

+/* utils.c */
+extern struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);
+
+#ifndef lru_to_page
+#define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
+#endif
+
#endif

diff --git a/drivers/staging/erofs/utils.c b/drivers/staging/erofs/utils.c
new file mode 100644
index 0000000..3dec4f8
--- /dev/null
+++ b/drivers/staging/erofs/utils.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/utils.c
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include "internal.h"
+
+struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
+{
+ struct page *page;
+
+ if (!list_empty(pool)) {
+ page = lru_to_page(pool);
+ list_del(&page->lru);
+ } else {
+ page = alloc_pages(gfp | __GFP_NOFAIL, 0);
+
+ BUG_ON(page == NULL);
+ BUG_ON(page->mapping != NULL);
+ }
+ return page;
+}
+
--
1.9.1
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