smb: client: fix filename matching of deferred files

Fix the following case where the client would end up closing both
deferred files (foo.tmp & foo) after unlink(foo) due to strstr() call
in cifs_close_deferred_file_under_dentry():

  fd1 = openat(AT_FDCWD, "foo", O_WRONLY|O_CREAT|O_TRUNC, 0666);
  fd2 = openat(AT_FDCWD, "foo.tmp", O_WRONLY|O_CREAT|O_TRUNC, 0666);
  close(fd1);
  close(fd2);
  unlink("foo");

Fixes: e3fc065 ("cifs: Deferred close performance improvements")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de>
Cc: Frank Sorenson <sorenson@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pcacjr

fs/smb/client/cifsproto.h

@@ -312,8 +312,8 @@ extern void cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode);
 
 extern void cifs_close_all_deferred_files(struct cifs_tcon *cifs_tcon);
 
-extern void cifs_close_deferred_file_under_dentry(struct cifs_tcon *cifs_tcon,
-				const char *path);
+void cifs_close_deferred_file_under_dentry(struct cifs_tcon *cifs_tcon,
+					   struct dentry *dentry);
 
 extern void cifs_mark_open_handles_for_deleted_file(struct inode *inode,
 				const char *path);

fs/smb/client/inode.c

@@ -1984,7 +1984,7 @@ static int __cifs_unlink(struct inode *dir, struct dentry *dentry, bool sillyren
 	}
 
 	netfs_wait_for_outstanding_io(inode);
-	cifs_close_deferred_file_under_dentry(tcon, full_path);
+	cifs_close_deferred_file_under_dentry(tcon, dentry);
 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
 	if (cap_unix(tcon->ses) && (CIFS_UNIX_POSIX_PATH_OPS_CAP &
 				le64_to_cpu(tcon->fsUnixInfo.Capability))) {
@@ -2538,10 +2538,10 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir,
 		goto cifs_rename_exit;
 	}
 
-	cifs_close_deferred_file_under_dentry(tcon, from_name);
+	cifs_close_deferred_file_under_dentry(tcon, source_dentry);
 	if (d_inode(target_dentry) != NULL) {
 		netfs_wait_for_outstanding_io(d_inode(target_dentry));
-		cifs_close_deferred_file_under_dentry(tcon, to_name);
+		cifs_close_deferred_file_under_dentry(tcon, target_dentry);
 	}
 
 	rc = cifs_do_rename(xid, source_dentry, from_name, target_dentry,

fs/smb/client/misc.c

@@ -832,33 +832,28 @@ cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 		kfree(tmp_list);
 	}
 }
-void
-cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
+
+void cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon,
+					   struct dentry *dentry)
 {
-	struct cifsFileInfo *cfile;
 	struct file_list *tmp_list, *tmp_next_list;
-	void *page;
-	const char *full_path;
+	struct cifsFileInfo *cfile;
 	LIST_HEAD(file_head);
 
-	page = alloc_dentry_path();
 	spin_lock(&tcon->open_file_lock);
 	list_for_each_entry(cfile, &tcon->openFileList, tlist) {
-		full_path = build_path_from_dentry(cfile->dentry, page);
-		if (strstr(full_path, path)) {
-			if (delayed_work_pending(&cfile->deferred)) {
-				if (cancel_delayed_work(&cfile->deferred)) {
-					spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
-					cifs_del_deferred_close(cfile);
-					spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
-
-					tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
-					if (tmp_list == NULL)
-						break;
-					tmp_list->cfile = cfile;
-					list_add_tail(&tmp_list->list, &file_head);
-				}
-			}
+		if ((cfile->dentry == dentry) &&
+		    delayed_work_pending(&cfile->deferred) &&
+		    cancel_delayed_work(&cfile->deferred)) {
+			spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+			cifs_del_deferred_close(cfile);
+			spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+
+			tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+			if (tmp_list == NULL)
+				break;
+			tmp_list->cfile = cfile;
+			list_add_tail(&tmp_list->list, &file_head);
 		}
 	}
 	spin_unlock(&tcon->open_file_lock);
@@ -868,7 +863,6 @@ cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 		list_del(&tmp_list->list);
 		kfree(tmp_list);
 	}
-	free_dentry_path(page);
 }
 
 /*