linux-kernel - [PATCH 3/3] fuse: writepage: skip already in flight

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Date:	Thu, 19 Sep 2013 18:11:56 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	mpatlasov@...allels.com
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Miklos Szeredi <mszeredi@...e.cz>
Subject: [PATCH 3/3] fuse: writepage: skip already in flight

From: Miklos Szeredi <mszeredi@...e.cz>

If ->writepage() tries to write back a page whose copy is still in flight,
then just skip by calling redirty_page_for_writepage().

This is OK, since now ->writepage() should never be called for data
integrity sync.

Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
---
 fs/fuse/file.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f8ff019..135360e 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1591,6 +1591,18 @@ static int fuse_writepage(struct page *page, struct writeback_control *wbc)
 {
 	int err;
 
+	if (fuse_page_is_writeback(page->mapping->host, page->index)) {
+		/*
+		 * ->writepages() should be called for sync() and friends.  We
+		 * should only get here on direct reclaim and then we are
+		 * allowed to skip a page which is already in flight
+		 */
+		WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
+
+		redirty_page_for_writepage(wbc, page);
+		return 0;
+	}
+
 	err = fuse_writepage_locked(page);
 	unlock_page(page);
 
-- 
1.8.1.4

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