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From: Chengguang Xu <cgxu519@mykernel.net>
To: miklos@szeredi.hu, amir73il@gmail.com, jack@suse.cz
Cc: linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Chengguang Xu <cgxu519@mykernel.net>
Subject: [RFC PATCH v2 2/8] ovl: implement ->writepages operation
Date: Sun, 25 Oct 2020 11:41:11 +0800
Message-ID: <20201025034117.4918-3-cgxu519@mykernel.net> (raw)
In-Reply-To: <20201025034117.4918-1-cgxu519@mykernel.net>

Implement overlayfs' ->writepages operation so that
we can sync dirty data/metadata to upper filesystem.

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
---
 fs/overlayfs/inode.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index b584dca845ba..f27fc5be34df 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -11,6 +11,7 @@
 #include <linux/posix_acl.h>
 #include <linux/ratelimit.h>
 #include <linux/fiemap.h>
+#include <linux/writeback.h>
 #include "overlayfs.h"
 
 
@@ -516,7 +517,32 @@ static const struct inode_operations ovl_special_inode_operations = {
 	.update_time	= ovl_update_time,
 };
 
+static int ovl_writepages(struct address_space *mapping,
+			  struct writeback_control *wbc)
+{
+	struct inode *upper_inode = ovl_inode_upper(mapping->host);
+	struct ovl_fs *ofs =  mapping->host->i_sb->s_fs_info;
+	struct writeback_control tmp_wbc = *wbc;
+
+	if (!ovl_should_sync(ofs))
+		return 0;
+
+	/*
+	 * for sync(2) writeback, it has a separate external IO
+	 * completion path by checking PAGECACHE_TAG_WRITEBACK
+	 * in pagecache, we have to set for_sync to 0 in thie case,
+	 * let writeback waits completion after syncing individual
+	 * dirty inode, because we haven't implemented overlayfs'
+	 * own pagecache yet.
+	 */
+	if (wbc->for_sync && (wbc->sync_mode == WB_SYNC_ALL))
+		tmp_wbc.for_sync = 0;
+
+	return sync_inode(upper_inode, &tmp_wbc);
+}
+
 static const struct address_space_operations ovl_aops = {
+	.writepages		= ovl_writepages,
 	/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
 	.direct_IO		= noop_direct_IO,
 };
-- 
2.26.2



  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-25  3:41 [RFC PATCH v2 0/8] implement containerized syncfs for overlayfs Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 1/8] ovl: setup overlayfs' private bdi Chengguang Xu
2020-10-25  3:41 ` Chengguang Xu [this message]
2020-11-02 17:17   ` [RFC PATCH v2 2/8] ovl: implement ->writepages operation Jan Kara
2020-11-04 12:18     ` Chengguang Xu
2020-11-05 13:55       ` Jan Kara
2020-11-06  5:57         ` Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 3/8] ovl: implement overlayfs' ->evict_inode operation Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 4/8] ovl: mark overlayfs' inode dirty on modification Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 5/8] ovl: mark overlayfs' inode dirty on shared writable mmap Chengguang Xu
2020-11-02 17:30   ` Jan Kara
2020-11-04 11:54     ` Chengguang Xu
2020-11-05 14:03       ` Jan Kara
2020-11-05 14:21         ` Amir Goldstein
2020-11-05 15:54           ` Jan Kara
2020-11-06  2:41             ` Chengguang Xu
2020-11-06  8:50               ` Jan Kara
2020-11-06  9:47                 ` Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 6/8] ovl: implement overlayfs' ->write_inode operation Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 7/8] ovl: cache dirty overlayfs' inode Chengguang Xu
2020-10-25  3:41 ` [RFC PATCH v2 8/8] ovl: implement containerized syncfs for overlayfs Chengguang Xu
2020-10-30 15:46 ` [RFC PATCH v2 0/8] " Miklos Szeredi
2020-10-31 12:22   ` Chengguang Xu

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