From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751886AbbCVIQW (ORCPT ); Sun, 22 Mar 2015 04:16:22 -0400 Received: from mail-pa0-f43.google.com ([209.85.220.43]:35643 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751611AbbCVIPJ (ORCPT ); Sun, 22 Mar 2015 04:15:09 -0400 From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Al Viro , Maxim Patlasov , Ming Lei Subject: [PATCH 1/3] block: loop: use kmap(page) instead of page_address(page) Date: Sun, 22 Mar 2015 16:14:52 +0800 Message-Id: <1427012095-4095-2-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1427012095-4095-1-git-send-email-ming.lei@canonical.com> References: <1427012095-4095-1-git-send-email-ming.lei@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The raw page allocated in lo_send() can be a highmem page, so kmap(page) should be used for read/write on the page. Also the patch removes kmap()/kunmap() in lo_send() because it isn't needed at all. Signed-off-by: Ming Lei --- drivers/block/loop.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index d1f168b..965f117 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -275,10 +275,13 @@ static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec, { int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page, bvec->bv_offset, bvec->bv_len, pos >> 9); - if (likely(!ret)) - return __do_lo_send_write(lo->lo_backing_file, - page_address(page), bvec->bv_len, + if (likely(!ret)) { + ret = __do_lo_send_write(lo->lo_backing_file, + kmap(page), bvec->bv_len, pos); + kunmap(page); + return ret; + } printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, " "length %i.\n", (unsigned long long)pos, bvec->bv_len); if (ret > 0) @@ -299,7 +302,6 @@ static int lo_send(struct loop_device *lo, struct request *rq, loff_t pos) page = alloc_page(GFP_NOIO | __GFP_HIGHMEM); if (unlikely(!page)) goto fail; - kmap(page); do_lo_send = do_lo_send_write; } else { do_lo_send = do_lo_send_direct_write; @@ -312,7 +314,6 @@ static int lo_send(struct loop_device *lo, struct request *rq, loff_t pos) pos += bvec.bv_len; } if (page) { - kunmap(page); __free_page(page); } out: -- 1.7.9.5