From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752710AbbDEHZf (ORCPT ); Sun, 5 Apr 2015 03:25:35 -0400 Received: from mail-pa0-f44.google.com ([209.85.220.44]:36111 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114AbbDEHZc (ORCPT ); Sun, 5 Apr 2015 03:25:32 -0400 From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org, Christoph Hellwig , Tejun Heo Cc: Andrew Morton , Alexander Viro , Jarod Wilson , David Herrmann , Markus Pargmann , nbd-general@lists.sourceforge.net, Stefan Haberland , Sebastian Ott , Fabian Frederick , linux-s390@vger.kernel.org, Ming Lei Subject: [PATCH 3/6] block: loop: fix another reread part failure Date: Sun, 5 Apr 2015 15:24:45 +0800 Message-Id: <1428218688-4092-4-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1428218688-4092-1-git-send-email-ming.lei@canonical.com> References: <1428218688-4092-1-git-send-email-ming.lei@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org loop_clr_fd() can be run piggyback with lo_release(), and under this situation, reread partition may always fail because of bd_mutex which has been held in release path. This patch detects the situation by the reference count, and call blkdev_reread_part_nolock() to avoid acquiring the lock again. In the meantime, this patch switches to new kernel APIs of blkdev_reread_part() and blkdev_reread_part_nolock(). Signed-off-by: Ming Lei --- drivers/block/loop.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 81a6bc1..80c9d87 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -528,6 +528,26 @@ static int loop_flush(struct loop_device *lo) return loop_switch(lo, NULL); } +static void loop_reread_partitions(struct loop_device *lo, + struct block_device *bdev) +{ + int rc; + bool in_release; + + mutex_lock(&lo->lo_open_mutex); + in_release = lo->lo_refcnt == 0; + mutex_unlock(&lo->lo_open_mutex); + + /* bd_mutex has been held already in release path */ + if (in_release) + rc = blkdev_reread_part_nolock(bdev); + else + rc = blkdev_reread_part(bdev); + if (rc) + pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", + __func__, lo->lo_number, lo->lo_file_name, rc); +} + /* * loop_change_fd switched the backing store of a loopback device to * a new file. This is useful for operating system installers to free up @@ -576,7 +596,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, fput(old_file); if (lo->lo_flags & LO_FLAGS_PARTSCAN) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); return 0; out_putf: @@ -807,7 +827,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, if (part_shift) lo->lo_flags |= LO_FLAGS_PARTSCAN; if (lo->lo_flags & LO_FLAGS_PARTSCAN) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); /* Grab the block_device to prevent its destruction after we * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). @@ -933,7 +953,7 @@ static int loop_clr_fd(struct loop_device *lo) mutex_unlock(&lo->lo_open_mutex); if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); lo->lo_flags = 0; if (!part_shift) lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; @@ -1008,7 +1028,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { lo->lo_flags |= LO_FLAGS_PARTSCAN; lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; - ioctl_by_bdev(lo->lo_device, BLKRRPART, 0); + loop_reread_partitions(lo, lo->lo_device); } lo->lo_encrypt_key_size = info->lo_encrypt_key_size; -- 1.7.9.5