fuse: fsync() did not return IO errors

Due to implementation of fuse writeback filemap_write_and_wait_range() does
not catch errors. We have to do this directly after fuse_sync_writes()

Signed-off-by: Alexey Kuznetsov <kuznet@virtuozzo.com>
Signed-off-by: Maxim Patlasov <mpatlasov@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 4d99ff8f12 ("fuse: Turn writeback cache on")
Cc: <stable@vger.kernel.org> # v3.15+

fs/fuse/file.c

@@ -462,6 +462,21 @@ int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 		goto out;
 
 	fuse_sync_writes(inode);
+
+	/*
+	 * Due to implementation of fuse writeback
+	 * filemap_write_and_wait_range() does not catch errors.
+	 * We have to do this directly after fuse_sync_writes()
+	 */
+	if (test_bit(AS_ENOSPC, &file->f_mapping->flags) &&
+	    test_and_clear_bit(AS_ENOSPC, &file->f_mapping->flags))
+		err = -ENOSPC;
+	if (test_bit(AS_EIO, &file->f_mapping->flags) &&
+	    test_and_clear_bit(AS_EIO, &file->f_mapping->flags))
+		err = -EIO;
+	if (err)
+		goto out;
+
 	err = sync_inode_metadata(inode, 1);
 	if (err)
 		goto out;