linux-kernel - [PATCH 4.9 44/48] xfs: dont change inode mode if ACL update fails

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Date:   Tue, 24 Oct 2017 15:03:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dave Chinner <dchinner@...hat.com>,
        Brian Foster <bfoster@...hat.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH 4.9 44/48] xfs: dont change inode mode if ACL update fails

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

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

From: Dave Chinner <dchinner@...hat.com>

commit 67f2ffe31d1a683170c2ba0ecc643e42a5fdd397 upstream.

If we get ENOSPC half way through setting the ACL, the inode mode
can still be changed even though the ACL does not exist. Reorder the
operation to only change the mode of the inode if the ACL is set
correctly.

Whilst this does not fix the problem with crash consistency (that requires
attribute addition to be a deferred op) it does prevent ENOSPC and other
non-fatal errors setting an xattr to be handled sanely.

This fixes xfstests generic/449.

Signed-Off-By: Dave Chinner <dchinner@...hat.com>
Reviewed-by: Brian Foster <bfoster@...hat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/xfs/xfs_acl.c |   22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -247,6 +247,8 @@ xfs_set_mode(struct inode *inode, umode_
 int
 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 {
+	umode_t mode;
+	bool set_mode = false;
 	int error = 0;

 	if (!acl)
@@ -257,16 +259,24 @@ xfs_set_acl(struct inode *inode, struct
 		return error;

 	if (type == ACL_TYPE_ACCESS) {
-		umode_t mode;
-
 		error = posix_acl_update_mode(inode, &mode, &acl);
 		if (error)
 			return error;
-		error = xfs_set_mode(inode, mode);
-		if (error)
-			return error;
+		set_mode = true;
 	}

  set_acl:
-	return __xfs_set_acl(inode, acl, type);
+	error =  __xfs_set_acl(inode, acl, type);
+	if (error)
+		return error;
+
+	/*
+	 * We set the mode after successfully updating the ACL xattr because the
+	 * xattr update can fail at ENOSPC and we don't want to change the mode
+	 * if the ACL update hasn't been applied.
+	 */
+	if (set_mode)
+		error = xfs_set_mode(inode, mode);
+
+	return error;
 }