Patch "ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ocfs2-revert-using-ocfs2_acl_chmod-to-avoid-inode-cluster-lock-hang.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Junxiao Bi <[email protected]>
Date: Thu, 12 May 2016 15:42:15 -0700
Subject: ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang

From: Junxiao Bi <[email protected]>

commit 5ee0fbd50fdf1c1329de8bee35ea9d7c6a81a2e0 upstream.

Commit 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()") introduced this issue. ocfs2_setattr called by chmod command holds cluster wide inode lock when calling posix_acl_chmod. This latter function in turn calls ocfs2_iop_get_acl and ocfs2_iop_set_acl. These two are also called directly from vfs layer for getfacl/setfacl commands and therefore acquire the cluster wide inode lock. If a remote conversion request comes after the first inode lock in ocfs2_setattr, OCFS2_LOCK_BLOCKED will be set. And this will cause the second call to inode lock from the ocfs2_iop_get_acl() to block indefinetly.

The deleted version of ocfs2_acl_chmod() calls __posix_acl_chmod() which does not call back into the filesystem. Therefore, we restore ocfs2_acl_chmod(), modify it slightly for locking as needed, and use that instead.

---
 fs/ocfs2/acl.c  |   24 ++++++++++++++++++++++++
 fs/ocfs2/acl.h  |    1 +
 fs/ocfs2/file.c |    4 ++--
 3 files changed, 27 insertions(+), 2 deletions(-)

@@ -322,3 +322,27 @@ struct posix_acl *ocfs2_iop_get_acl(stru
 	brelse(di_bh);
 	return acl;
 }
+
+int ocfs2_acl_chmod(struct inode *inode, struct buffer_head *bh)
+{
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct posix_acl *acl;
+	int ret;
+
+	if (S_ISLNK(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	if (!(osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL))
+		return 0;
+
+	acl = ocfs2_get_acl_nolock(inode, ACL_TYPE_ACCESS, bh);
+	if (IS_ERR(acl) || !acl)
+		return PTR_ERR(acl);
+	ret = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
+	if (ret)
+		return ret;
+	ret = ocfs2_set_acl(NULL, inode, NULL, ACL_TYPE_ACCESS,
+			    acl, NULL, NULL);
+	posix_acl_release(acl);
+	return ret;
+}

@@ -35,5 +35,6 @@ int ocfs2_set_acl(handle_t *handle,
 			 struct posix_acl *acl,
 			 struct ocfs2_alloc_context *meta_ac,
 			 struct ocfs2_alloc_context *data_ac);
+extern int ocfs2_acl_chmod(struct inode *, struct buffer_head *);
 
 #endif /* OCFS2_ACL_H */

@@ -1268,20 +1268,20 @@ bail_unlock_rw:
 	if (size_change)
 		ocfs2_rw_unlock(inode, 1);
 bail:
-	brelse(bh);
 
 	/* Release quota pointers in case we acquired them */
 	for (qtype = 0; qtype < OCFS2_MAXQUOTAS; qtype++)
 		dqput(transfer_to[qtype]);
 
 	if (!status && attr->ia_valid & ATTR_MODE) {
-		status = posix_acl_chmod(inode, inode->i_mode);
+		status = ocfs2_acl_chmod(inode, bh);
 		if (status < 0)
 			mlog_errno(status);
 	}
 	if (inode_locked)
 		ocfs2_inode_unlock(inode, 1);
 
+	brelse(bh);
 	return status;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/ocfs2-fix-posix_acl_create-deadlock.patch queue-4.5/ocfs2-revert-using-ocfs2_acl_chmod-to-avoid-inode-cluster-lock-hang.patch