linux-ext4 - patch ext4: fix data exposure after a crash still work ?

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Date:   Tue, 6 Dec 2016 09:52:01 +0000
From:   "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@...bosch.com>
To:     Jan Kara <jack@...e.cz>
CC:     "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: patch ext4: fix data exposure after a crash still work ?

Hi Kara

Since we move to kernel 3.18 stable branch. i found the patch " ext4: fix data exposure after a crash " not available but I found below commit which mentioned that patch.
I want to check with you whether " ext4: fix data exposure after a crash " still needed currently ?
I guess yes but I want to confirm with you.
Thanks
Huang weller

ext4: fix deadlock during page writeback
[ Upstream commit 646caa9c8e196880b41cd3e3d33a2ebc752bdb85 ]

Commit 06bd3c36a733 (ext4: fix data exposure after a crash) uncovered a
deadlock in ext4_writepages() which was previously much harder to hit.
After this commit xfstest generic/130 reproduces the deadlock on small
filesystems.

The problem happens when ext4_do_update_inode() sets LARGE_FILE feature
and marks current inode handle as synchronous. That subsequently results
in ext4_journal_stop() called from ext4_writepages() to block waiting for
transaction commit while still holding page locks, reference to io_end,
and some prepared bio in mpd structure each of which can possibly block
transaction commit from completing and thus results in deadlock.

Fix the problem by releasing page locks, io_end reference, and
submitting prepared bio before calling ext4_journal_stop().

[ Changed to defer the call to ext4_journal_stop() only if the handle
  is synchronous.  --tytso ]

Best regards

 Weller HUANG

Base SW (CM/ESW12-CN) 
Bosch Automotive Products (Suzhou) Co. Ltd | No. 126, Su Hong Xi Road
Suzhou Industrial Park | Suzhou P.R.China | P.R.CHINA 
Tel. +86(512)6767-4518 | Weller.Huang@...bosch.com

Sitz: Suzhou, Registergericht: State Administration of Industry & Commerce, P.R.China 
Board of Directors: Yudong Chen, Patrick Leinenbach, Liming Chen

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