Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758101Ab3GYSLY (ORCPT ); Thu, 25 Jul 2013 14:11:24 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:19807 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756859Ab3GYRvy (ORCPT ); Thu, 25 Jul 2013 13:51:54 -0400 From: Dave Kleikamp To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, Andrew Morton , "Maxim V. Patlasov" , Zach Brown , Dave Kleikamp Subject: [PATCH V8 07/33] iov_iter: ii_iovec_copy_to_user should pre-fault user pages Date: Thu, 25 Jul 2013 12:50:33 -0500 Message-Id: <1374774659-13121-8-git-send-email-dave.kleikamp@oracle.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1374774659-13121-1-git-send-email-dave.kleikamp@oracle.com> References: <1374774659-13121-1-git-send-email-dave.kleikamp@oracle.com> X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1509 Lines: 55 This duplicates the optimization in file_read_actor as a later patch will replace it with a call to __iov_iter_copy_to_user(). Signed-off-by: Dave Kleikamp --- fs/iov-iter.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/fs/iov-iter.c b/fs/iov-iter.c index 6cb6be0..59f9556 100644 --- a/fs/iov-iter.c +++ b/fs/iov-iter.c @@ -80,17 +80,32 @@ static size_t ii_iovec_copy_to_user(struct page *page, return 0; } - kaddr = kmap(page); if (likely(i->nr_segs == 1)) { int left; char __user *buf = iov->iov_base + i->iov_offset; + /* + * Faults on the destination of a read are common, so do it + * before taking the kmap. + */ + if (!fault_in_pages_writeable(buf, bytes)) { + kaddr = kmap_atomic(page); + left = __copy_to_user_inatomic(buf, kaddr + offset, + bytes); + kunmap_atomic(kaddr); + if (left == 0) + goto success; + } + kaddr = kmap(page); left = copy_to_user(buf, kaddr + offset, bytes); + kunmap(page); +success: copied = bytes - left; } else { + kaddr = kmap(page); copied = __iovec_copy_to_user(kaddr + offset, iov, i->iov_offset, bytes, 0); + kunmap(page); } - kunmap(page); return copied; } -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/