linux-ext4 - [Bug 16165] Wrong data returned on read after write if file size was changed with ftruncate before

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Message-Id: <201006181530.o5IFUIZh002098@demeter.kernel.org>
Date:	Fri, 18 Jun 2010 15:30:18 GMT
From:	bugzilla-daemon@...zilla.kernel.org
To:	linux-ext4@...r.kernel.org
Subject: [Bug 16165] Wrong data returned on read after write if file size was
 changed with ftruncate before

https://bugzilla.kernel.org/show_bug.cgi?id=16165





--- Comment #12 from Eric Sandeen <sandeen@...hat.com>  2010-06-18 15:30:13 ---
Can those who can reproduce this test this patch from mingming?

When unaligned DIO writes, skip zero out the block if the buffer is marked
unwritten. That means there is an asynconous direct IO (append or fill the
hole)
still pending.

Signed-off-by: Mingming Cao <cmm@...ibm.com>
---
 fs/direct-io.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-git/fs/direct-io.c
===================================================================
--- linux-git.orig/fs/direct-io.c    2010-05-07 15:42:22.855033403 -0700
+++ linux-git/fs/direct-io.c    2010-05-07 15:44:17.695007770 -0700
@@ -740,7 +740,8 @@
     struct page *page;

     dio->start_zero_done = 1;
-    if (!dio->blkfactor || !buffer_new(&dio->map_bh))
+    if (!dio->blkfactor || !buffer_new(&dio->map_bh)
+        || buffer_unwritten(&dio->map_bh))
         return;

     dio_blocks_per_fs_block = 1 << dio->blkfactor;

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