FAILED: patch "[PATCH] ceph: fix recursion between ceph_set_acl() and" failed to apply to 4.4-stable tree

From 8179a101eb5f4ef0ac9a915fcea9a9d3109efa90 Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

From beab414f9df0c865e73e651393538cde1fa20a3d Mon Sep 17 00:00:00 2001

Quoted 6 lines · Greg Kroah-Hartman

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Here's a backport I've tested with 4.4.

Cheers,
--
Luís

From beab414f9df0c865e73e651393538cde1fa20a3d Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <[email protected]>
Date: Wed, 19 Apr 2017 10:01:48 +0800
Subject: [PATCH] ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

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.

Cc [email protected] # needs backporting for < 4.9

Link http://tracker.ceph.com/issues/19688

Reported-by Jerry Lee <[email protected]>

Signed-off-by "Yan, Zheng" <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

Tested-by Luis Henriques <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

[luis: __ceph_setattr doesn't exist in 4.4, implement all the changes directly in ceph_setattr. The wrapper function was introduced only in commit a26feccaba29 ("ceph: Get rid of d_find_alias in ceph_set_acl").]

Signed-off-by Luis Henriques <[email protected]>

---
fs/ceph/inode.c | 18 +++++++-----------

1 file changed, 7 insertions(+), 11 deletions(-)

fs/ceph/inode.c +0 -11

index d98536c8abfc..e3d19c3d246d 100644
@@ -1975,11 +1975,6 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	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;

@@ -1993,13 +1988,14 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	     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);

Thank you for the patch. but it does not work because ceph_set_acl() calls ceph_setattr() directly. I think we need to introduce __ceph_setattr() and make ceph_set_acl() call __ceph_setattr()

From a6751ca41e6096638b75bf9d066338571399e8b4 Mon Sep 17 00:00:00 2001

On Tue, May 02, 2017 at 07:19:06PM +0800, Yan, Zheng wrote:
[...]

Quoted 3 lines

Thank you for the patch. but it does not work because ceph_set_acl() calls ceph_setattr() directly. I think we need to introduce __ceph_setattr() and make ceph_set_acl() call __ceph_setattr()

Ah, of course! Maybe something like this:

From a6751ca41e6096638b75bf9d066338571399e8b4 Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <[email protected]>
Date: Wed, 19 Apr 2017 10:01:48 +0800
Subject: [PATCH] ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

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.

Cc [email protected] # needs backporting for < 4.9

Link http://tracker.ceph.com/issues/19688

Reported-by Jerry Lee <[email protected]>

Signed-off-by "Yan, Zheng" <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

Tested-by Luis Henriques <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

[luis: introduce __ceph_setattr() and make ceph_set_acl() call it, as suggested by Yan.]

Signed-off-by Luis Henriques <[email protected]>

---

fs/ceph/acl.c   |  4 ++--
fs/ceph/inode.c | 27 ++++++++++++++++-----------
fs/ceph/super.h |  1 +
3 files changed, 19 insertions(+), 13 deletions(-)

fs/ceph/acl.c +2 -2

index 4d8caeb94a11..bdb9c94335f1 100644
@@ -128,7 +128,7 @@ int ceph_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	if (new_mode != old_mode) {
 		newattrs.ia_mode = new_mode;
 		newattrs.ia_valid = ATTR_MODE;
-		ret = ceph_setattr(dentry, &newattrs);
+		ret = __ceph_setattr(dentry, &newattrs);
 		if (ret)
 			goto out_dput;
 	}

@@ -138,7 +138,7 @@ int ceph_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 		if (new_mode != old_mode) {
 			newattrs.ia_mode = old_mode;
 			newattrs.ia_valid = ATTR_MODE;
-			ceph_setattr(dentry, &newattrs);
+			__ceph_setattr(dentry, &newattrs);
 		}
 		goto out_dput;
 	}

fs/ceph/inode.c +16 -11

index d98536c8abfc..9f0d99094cc1 100644
@@ -1773,7 +1773,7 @@ static const struct inode_operations ceph_symlink_iops = {
 /*
 * setattr
 */
-int ceph_setattr(struct dentry *dentry, struct iattr *attr)
+int __ceph_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct ceph_inode_info *ci = ceph_inode(inode);

@@ -1975,11 +1975,6 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	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;

@@ -1993,13 +1988,23 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	     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);
+
+	if (err >= 0 && (mask & CEPH_SETATTR_SIZE))
+		__ceph_do_pending_vmtruncate(inode);
+
 	return err;
-out_put:
-	ceph_mdsc_put_request(req);
-	ceph_free_cap_flush(prealloc_cf);
+}
+
+int ceph_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	int err;
+
+	err = __ceph_setattr(dentry, attr);
+
+	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
+		err = posix_acl_chmod(d_inode(dentry), attr->ia_mode);
+
 	return err;
 }
 

fs/ceph/super.h +0 -0

index 75b7d125ce66..8c8cb8fe3d32 100644