Merge pull request #4 from gwu-ddn/redfs-6.8

fuse: fix race between concurrent setattrs from multiple nodes

Author: bsbernd

fs/fuse/dir.c

@@ -1889,6 +1889,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 	int err;
 	bool trust_local_cmtime = is_wb;
 	bool fault_blocked = false;
+	u64 attr_version;
 
 	if (!fc->default_permissions)
 		attr->ia_valid |= ATTR_FORCE;
@@ -1973,6 +1974,8 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		if (fc->handle_killpriv_v2 && !capable(CAP_FSETID))
 			inarg.valid |= FATTR_KILL_SUIDGID;
 	}
+
+	attr_version = fuse_get_attr_version(fm->fc);
 	fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
 	err = fuse_simple_request(fm, &args);
 	if (err) {
@@ -1998,6 +2001,14 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		/* FIXME: clear I_DIRTY_SYNC? */
 	}
 
+	if (fi->attr_version > attr_version) {
+		/*
+		 * Apply attributes, for example for fsnotify_change(), but set
+		 * attribute timeout to zero.
+		 */
+		outarg.attr_valid = outarg.attr_valid_nsec = 0;
+	}
+
 	fuse_change_attributes_common(inode, &outarg.attr, NULL,
 				      ATTR_TIMEOUT(&outarg),
 				      fuse_get_cache_mask(inode), 0);