From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757993Ab1ANRAZ (ORCPT ); Fri, 14 Jan 2011 12:00:25 -0500 Received: from emroute3.ornl.gov ([160.91.4.110]:58892 "EHLO emroute3.ornl.gov" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757553Ab1ANRAN (ORCPT ); Fri, 14 Jan 2011 12:00:13 -0500 X-Greylist: delayed 833 seconds by postgrey-1.27 at vger.kernel.org; Fri, 14 Jan 2011 12:00:12 EST Date: Fri, 14 Jan 2011 11:46:24 -0500 From: David Dillow Subject: [PATCH v2 alt 2] fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio In-reply-to: To: Jeff Moyer Cc: "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" Message-id: <1295023584.24487.16.camel@lap75545.ornl.gov> Organization: Oak Ridge National Laboratory MIME-version: 1.0 X-Mailer: Evolution 2.32.1 (2.32.1-1.fc14) Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit References: <1294977946.21790.20.camel@obelisk.thedillows.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When using devices that support max_segments > BIO_MAX_PAGES (256), direct IO tries to allocate a bio with more pages than allowed, which leads to an oops in dio_bio_alloc(). Clamp the request to the supported maximum, and change dio_bio_alloc() to reflect that bio_alloc() will always return a bio when called with __GFP_WAIT and a valid number of vectors. Signed-off-by: David Dillow -- Second alternate, my preferred that reflects that bio_alloc() cannot fail when properly called. I can take or leave the comment. diff --git a/fs/direct-io.c b/fs/direct-io.c index 85882f6..96a01d8 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -325,13 +325,17 @@ void dio_end_io(struct bio *bio, int error) } EXPORT_SYMBOL_GPL(dio_end_io); -static int +static void dio_bio_alloc(struct dio *dio, struct block_device *bdev, sector_t first_sector, int nr_vecs) { struct bio *bio; + /* bio_alloc() is guaranteed to return a bio when called with + * __GFP_WAIT and we request a valid number of vectors. + */ bio = bio_alloc(GFP_KERNEL, nr_vecs); + BUG_ON(!bio); bio->bi_bdev = bdev; bio->bi_sector = first_sector; @@ -342,7 +346,6 @@ dio_bio_alloc(struct dio *dio, struct block_device *bdev, dio->bio = bio; dio->logical_offset_in_bio = dio->cur_page_fs_offset; - return 0; } /* @@ -583,8 +586,9 @@ static int dio_new_bio(struct dio *dio, sector_t start_sector) goto out; sector = start_sector << (dio->blkbits - 9); nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); + nr_pages = min(nr_pages, BIO_MAX_PAGES); BUG_ON(nr_pages <= 0); - ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); + dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); dio->boundary = 0; out: return ret;