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From:   Gao Xiang <gaoxiang25@huawei.com>
To:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Theodore Ts'o <tytso@mit.edu>,
        "Linus Torvalds" <torvalds@linux-foundation.org>
CC:     <linux-fsdevel@vger.kernel.org>, <devel@driverdev.osuosl.org>,
        LKML <linux-kernel@vger.kernel.org>,
        <linux-erofs@lists.ozlabs.org>, Chao Yu <yuchao0@huawei.com>,
        Miao Xie <miaoxie@huawei.com>,
        Li Guifu <bluce.liguifu@huawei.com>,
        Fang Wei <fangwei1@huawei.com>,
        Gao Xiang <gaoxiang25@huawei.com>
Subject: [PATCH v3 19/24] erofs: add erofs_allocpage()
Date:   Mon, 22 Jul 2019 10:50:38 +0800
Message-ID: <20190722025043.166344-20-gaoxiang25@huawei.com>
In-Reply-To: <20190722025043.166344-1-gaoxiang25@huawei.com>
References: <20190722025043.166344-1-gaoxiang25@huawei.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
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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>
---
 fs/erofs/internal.h |  2 ++
 fs/erofs/utils.c    | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index dc5c6c5e4885..506a68efe507 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -495,6 +495,8 @@ int erofs_namei(struct inode *dir, struct qstr *name,
 extern const struct file_operations erofs_dir_fops;
 
 /* utils.c */
+struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp, bool nofail);
+
 #if (EROFS_PCPUBUF_NR_PAGES > 0)
 void *erofs_get_pcpubuf(unsigned int pagenr);
 #define erofs_put_pcpubuf(buf) do { \
diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c
index c430790a02e0..53ee6daa3f70 100644
--- a/fs/erofs/utils.c
+++ b/fs/erofs/utils.c
@@ -9,6 +9,20 @@
 #include "internal.h"
 #include <linux/pagevec.h>
 
+struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp, bool nofail)
+{
+	struct page *page;
+
+	if (!list_empty(pool)) {
+		page = lru_to_page(pool);
+		DBG_BUGON(page_ref_count(page) != 1);
+		list_del(&page->lru);
+	} else {
+		page = alloc_pages(gfp | (nofail ? __GFP_NOFAIL : 0), 0);
+	}
+	return page;
+}
+
 #if (EROFS_PCPUBUF_NR_PAGES > 0)
 static struct {
 	u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES];
-- 
2.17.1