From patchwork Sun Jul 31 18:15:13 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 9253431 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EE3E66048F for ; Sun, 31 Jul 2016 18:17:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D841F28483 for ; Sun, 31 Jul 2016 18:17:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CC8E42848C; Sun, 31 Jul 2016 18:17:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id CE6AE28483 for ; Sun, 31 Jul 2016 18:17:38 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 5BC861A1DF1; Sun, 31 Jul 2016 11:17:38 -0700 (PDT) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by ml01.01.org (Postfix) with ESMTP id B10F31A1DF1 for ; Sun, 31 Jul 2016 11:17:37 -0700 (PDT) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 31 Jul 2016 11:17:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos; i="5.28,451,1464678000"; d="scan'208"; a="1027227649" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.14]) by orsmga002.jf.intel.com with ESMTP; 31 Jul 2016 11:17:37 -0700 Subject: [PATCH] block: fix bdi vs gendisk lifetime mismatch From: Dan Williams To: axboe@fb.com Date: Sun, 31 Jul 2016 11:15:13 -0700 Message-ID: <146998891350.29275.1589003488607819550.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-block@vger.kernel.org, stable@vger.kernel.org, linux-nvdimm@lists.01.org Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [] dump_stack+0x63/0x87 [] __warn+0xd1/0xf0 [] warn_slowpath_fmt+0x5f/0x80 [] sysfs_warn_dup+0x64/0x80 [] sysfs_create_dir_ns+0x7e/0x90 [] kobject_add_internal+0xaa/0x320 [] ? vsnprintf+0x34e/0x4d0 [] kobject_add+0x75/0xd0 [] ? mutex_lock+0x12/0x2f [] device_add+0x125/0x610 [] device_create_groups_vargs+0xd8/0x100 [] device_create_vargs+0x1c/0x20 [] bdi_register+0x8c/0x180 [] bdi_register_dev+0x27/0x30 [] add_disk+0x175/0x4a0 Cc: Reported-by: Yi Zhang Tested-by: Yi Zhang Signed-off-by: Dan Williams --- block/genhd.c | 2 +- include/linux/backing-dev-defs.h | 1 + include/linux/backing-dev.h | 1 + mm/backing-dev.c | 18 ++++++++++++++++++ 4 files changed, 21 insertions(+), 1 deletion(-) diff --git a/block/genhd.c b/block/genhd.c index 3c9dede4e04f..f6f7ffcd4eab 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -614,7 +614,7 @@ void device_add_disk(struct device *parent, struct gendisk *disk) /* Register BDI before referencing it from bdev */ bdi = &disk->queue->backing_dev_info; - bdi_register_dev(bdi, disk_devt(disk)); + bdi_register_owner(bdi, disk_to_dev(disk)); blk_register_region(disk_devt(disk), disk->minors, NULL, exact_match, exact_lock, disk); diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 3f103076d0bf..c357f27d5483 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -163,6 +163,7 @@ struct backing_dev_info { wait_queue_head_t wb_waitq; struct device *dev; + struct device *owner; struct timer_list laptop_mode_wb_timer; diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 491a91717788..43b93a947e61 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -24,6 +24,7 @@ __printf(3, 4) int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...); int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner); void bdi_unregister(struct backing_dev_info *bdi); int __must_check bdi_setup_and_register(struct backing_dev_info *, char *); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index efe237742074..7b51cb7905be 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -825,6 +825,19 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) } EXPORT_SYMBOL(bdi_register_dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) +{ + int rc; + + rc = bdi_register(bdi, NULL, "%u:%u", MAJOR(owner->devt), + MINOR(owner->devt)); + if (rc) + return rc; + bdi->owner = owner; + get_device(owner); +} +EXPORT_SYMBOL(bdi_register_owner); + /* * Remove bdi from bdi_list, and ensure that it is no longer visible */ @@ -849,6 +862,11 @@ void bdi_unregister(struct backing_dev_info *bdi) device_unregister(bdi->dev); bdi->dev = NULL; } + + if (bdi->owner) { + put_device(bdi->owner); + bdi->owner = NULL; + } } void bdi_exit(struct backing_dev_info *bdi)