Patch "ceph: fix recursion between ceph_set_acl() and __ceph_setattr()" has been added to the 4.9-stable tree

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

ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

to the 4.9-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:
ceph-fix-recursion-between-ceph_set_acl-and-__ceph_setattr.patch
and it can be found in the queue-4.9 subdirectory.

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

From: "Yan, Zheng" <[email protected]>
Date: Wed, 19 Apr 2017 10:01:48 +0800
Subject: ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

From: Yan, Zheng <[email protected]>

commit 8179a101eb5f4ef0ac9a915fcea9a9d3109efa90 upstream.

ceph_set_acl() calls __ceph_setattr() if the setacl operation needs to modify inode's i_mode. __ceph_setattr() updates inode's i_mode, then calls posix_acl_chmod().

The problem is that __ceph_setattr() calls posix_acl_chmod() before sending the setattr request. The get_acl() call in posix_acl_chmod() can trigger a getxattr request. The reply of the getxattr request can restore inode's i_mode to its old value. The set_acl() call in posix_acl_chmod() sees old value of inode's i_mode, so it calls __ceph_setattr() again.

---
 fs/ceph/inode.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

@@ -2080,11 +2080,6 @@ int __ceph_setattr(struct inode *inode,
 	if (inode_dirty_flags)
 		__mark_inode_dirty(inode, inode_dirty_flags);
 
-	if (ia_valid & ATTR_MODE) {
-		err = posix_acl_chmod(inode, attr->ia_mode);
-		if (err)
-			goto out_put;
-	}
 
 	if (mask) {
 		req->r_inode = inode;

@@ -2098,13 +2093,11 @@ int __ceph_setattr(struct inode *inode,
 	     ceph_cap_string(dirtied), mask);
 
 	ceph_mdsc_put_request(req);
-	if (mask & CEPH_SETATTR_SIZE)
-		__ceph_do_pending_vmtruncate(inode);
-	ceph_free_cap_flush(prealloc_cf);
-	return err;
-out_put:
-	ceph_mdsc_put_request(req);
 	ceph_free_cap_flush(prealloc_cf);
+
+	if (err >= 0 && (mask & CEPH_SETATTR_SIZE))
+		__ceph_do_pending_vmtruncate(inode);
+
 	return err;
 }
 

@@ -2123,7 +2116,12 @@ int ceph_setattr(struct dentry *dentry,
 	if (err != 0)
 		return err;
 
-	return __ceph_setattr(inode, attr);
+	err = __ceph_setattr(inode, attr);
+
+	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
+		err = posix_acl_chmod(inode, attr->ia_mode);
+
+	return err;
 }
 
 /*

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

queue-4.9/ceph-fix-recursion-between-ceph_set_acl-and-__ceph_setattr.patch