Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "This contains fixes for a dentry leak, a regression in 4.6 noticed by
  Docker users and missing write access checking in truncate"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: warn instead of error if d_type is not supported
  ovl: get_write_access() in truncate
  ovl: fix dentry leak for default_permissions

2 files changed, 33 insertions, 8 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1dbeab6cf96e..c831c2e5f803 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -59,16 +59,37 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
         if (err)
                 goto out;
 
+        if (attr->ia_valid & ATTR_SIZE) {
+                struct inode *realinode = d_inode(ovl_dentry_real(dentry));
+
+                err = -ETXTBSY;
+                if (atomic_read(&realinode->i_writecount) < 0)
+                        goto out_drop_write;
+        }
+
         err = ovl_copy_up(dentry);
         if (!err) {
+                struct inode *winode = NULL;
+
                 upperdentry = ovl_dentry_upper(dentry);
 
+                if (attr->ia_valid & ATTR_SIZE) {
+                        winode = d_inode(upperdentry);
+                        err = get_write_access(winode);
+                        if (err)
+                                goto out_drop_write;
+                }
+
                 inode_lock(upperdentry->d_inode);
                 err = notify_change(upperdentry, attr, NULL);
                 if (!err)
                         ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
                 inode_unlock(upperdentry->d_inode);
+
+                if (winode)
+                        put_write_access(winode);
         }
+out_drop_write:
         ovl_drop_write(dentry);
 out:
         return err;
@@ -121,16 +142,18 @@ int ovl_permission(struct inode *inode, int mask)
 
                 err = vfs_getattr(&realpath, &stat);
                 if (err)
-                        return err;
+                        goto out_dput;
 
+                err = -ESTALE;
                 if ((stat.mode ^ inode->i_mode) & S_IFMT)
-                        return -ESTALE;
+                        goto out_dput;
 
                 inode->i_mode = stat.mode;
                 inode->i_uid = stat.uid;
                 inode->i_gid = stat.gid;
 
-                return generic_permission(inode, mask);
+                err = generic_permission(inode, mask);
+                goto out_dput;
         }
 
         /* Careful in RCU walk mode */
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index ce02f46029da..9a7693d5f8ff 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1082,11 +1082,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                         if (err < 0)
                                 goto out_put_workdir;
 
-                        if (!err) {
-                                pr_err("overlayfs: upper fs needs to support d_type.\n");
-                                err = -EINVAL;
-                                goto out_put_workdir;
-                        }
+                        /*
+                         * We allowed this configuration and don't want to
+                         * break users over kernel upgrade. So warn instead
+                         * of erroring out.
+                         */
+                        if (!err)
+                                pr_warn("overlayfs: upper fs needs to support d_type.\n");
                 }
         }