linux-kernel - [PATCH 4.4 40/49] Revert "ocfs2: should wait dio before inode lock in ocfs2

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Date:   Thu,  7 Dec 2017 14:07:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Alex Chen <alex.chen@...wei.com>,
        Jun Piao <piaojun@...wei.com>,
        Joseph Qi <jiangqi903@...il.com>,
        Changwei Ge <ge.changwei@....com>,
        Mark Fasheh <mfasheh@...sity.com>,
        Joel Becker <jlbec@...lplan.org>,
        Junxiao Bi <junxiao.bi@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 40/49] Revert "ocfs2: should wait dio before inode lock in ocfs2_setattr()"

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

This reverts commit c4baa4a5870cb02f713def1620052bfca7a82bbb which is
commit 28f5a8a7c033cbf3e32277f4cc9c6afd74f05300 upstream.

It shouldn't be applied to the 4.4-stable tree.

Ben and Alex write:

> Now that ocfs2_setattr() calls this outside of the inode locked region,
> what prevents another task adding a new dio request immediately
> afterward?
>

In the kernel 4.6, firstly, we use the inode_lock() in do_truncate() to
prevent another bio to be issued from this node.
Furthermore, we use the ocfs2_rw_lock() and ocfs2_inode_lock() in ocfs2_setattr()
to guarantee no more bio will be issued from the other nodes in this cluster.

> Also, ocfs2_dio_end_io_write() was introduced in 4.6 and it looks like
> the dio completion path didn't previously take the inode lock.  So it
> doesn't look this fix is needed in 3.18 or 4.4.

Yes, ocfs2_dio_end_io_write() was introduced in 4.6 and the problem this patch
fixes is only exist in the kernel 4.6 and above 4.6.

Reported-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Cc: Alex Chen <alex.chen@...wei.com>
Cc: Jun Piao <piaojun@...wei.com>
Cc: Joseph Qi <jiangqi903@...il.com>
Cc: Changwei Ge <ge.changwei@....com>
Cc: Mark Fasheh <mfasheh@...sity.com>
Cc: Joel Becker <jlbec@...lplan.org>
Cc: Junxiao Bi <junxiao.bi@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/ocfs2/file.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1166,13 +1166,6 @@ int ocfs2_setattr(struct dentry *dentry,
 	}
 	size_change = S_ISREG(inode->i_mode) && attr->ia_valid & ATTR_SIZE;
 	if (size_change) {
-		/*
-		 * Here we should wait dio to finish before inode lock
-		 * to avoid a deadlock between ocfs2_setattr() and
-		 * ocfs2_dio_end_io_write()
-		 */
-		inode_dio_wait(inode);
-
 		status = ocfs2_rw_lock(inode, 1);
 		if (status < 0) {
 			mlog_errno(status);
@@ -1193,6 +1186,8 @@ int ocfs2_setattr(struct dentry *dentry,
 		if (status)
 			goto bail_unlock;
 
+		inode_dio_wait(inode);
+
 		if (i_size_read(inode) >= attr->ia_size) {
 			if (ocfs2_should_order_data(inode)) {
 				status = ocfs2_begin_ordered_truncate(inode,