From patchwork Wed Apr 22 10:06:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martijn Coenen X-Patchwork-Id: 11503511 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A004E159A for ; Wed, 22 Apr 2020 10:56:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83C3F2076E for ; Wed, 22 Apr 2020 10:56:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="wCRZog2u" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726554AbgDVK4W (ORCPT ); Wed, 22 Apr 2020 06:56:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728395AbgDVKGp (ORCPT ); Wed, 22 Apr 2020 06:06:45 -0400 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F4090C03C1AA for ; Wed, 22 Apr 2020 03:06:44 -0700 (PDT) Received: by mail-wm1-x343.google.com with SMTP id v8so4530225wma.0 for ; Wed, 22 Apr 2020 03:06:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=F+0K7OIOKk8O51V5gNKinM3m15DeYTfEO7xsT25+AwY=; b=wCRZog2ujjq1VXrOoJzN2gxTVlzcdBgWGd3wj0+N+SFLxJ29cyO0YFt8VNRf5wO0nC ZQH2Gk7Q6cCNuGc9QTjkHwJXO7Hk0nDWCVOV2WP89hucJ9DSV9wdbxEmsJiuhuwKiA/s 7H2WPVbbwStLDHuxz8DSHCTRR15JUYRbay/2Xi9u+M1WKFPgbIHR+H+/Rn5sipM8/n3r u081iY2UAJC+76ZowLZMM8tQ8/Zy+sV6bJo633hYjILCUIZMZsvqbaIGfIQtJIsDY7qc w/kBe8QD68/OjBVnQVvwFyiN+QnrBHR+Z1qmFdKM9OBOk+zo/NKKauVi8+IpLAZLU1yH sz4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=F+0K7OIOKk8O51V5gNKinM3m15DeYTfEO7xsT25+AwY=; b=Q+NYcpEkyBe7fvBVbbMNNd4lesmi8ghVSR3DzNGEjh5E2aimN68orf+ixRx656CxNb gdwUUPyQhgq3w9PVaLef7MwZJ/JJ0p5q7WZWnShQzXF0cZLxMa3HDWpSfFjVIWzprpEv AMjvuBYU2uslpQ+MvRvscZWFuIEeaJgb8UQ169+qz43fs/uLM8m/vQubkz5y1MxxT3Vk Mo+zcMBLpwWsKaLejBSTu7ht7YAoFxG1yN+h35Hy9/Nw1G1cjnLAurrdhrTTbvmtqLB2 K6jwuLfScz+6R6t79vjN5n8bsZaLbzIyqIooPq6wk1DNL+jH/+gLkxL5RHiGomYIIOfm sHZQ== X-Gm-Message-State: AGi0Puae88Tdbf3egm4fOKKCGEbSXURkA3ArBxSE/6qHsO5hpkaCU/a0 HUkrLZ8YjydQ56d1AsBNEmSCmw== X-Google-Smtp-Source: APiQypIVrmoFnc4FjHc9aa3ZqH3XWubRL1wmduJTj/TKB0/OBgK9x8LJKNo/LKalhzxAomx4WTNxew== X-Received: by 2002:a1c:5448:: with SMTP id p8mr9466600wmi.173.1587550003569; Wed, 22 Apr 2020 03:06:43 -0700 (PDT) Received: from maco2.ams.corp.google.com (a83-162-234-235.adsl.xs4all.nl. [83.162.234.235]) by smtp.gmail.com with ESMTPSA id j13sm7812462wrq.24.2020.04.22.03.06.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2020 03:06:42 -0700 (PDT) From: Martijn Coenen To: axboe@kernel.dk, hch@lst.de, ming.lei@redhat.com Cc: narayan@google.com, zezeozue@google.com, kernel-team@android.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, maco@google.com, bvanassche@acm.org, Chaitanya.Kulkarni@wdc.com, jaegeuk@kernel.org, Martijn Coenen Subject: [PATCH v2 1/5] loop: Refactor size calculation Date: Wed, 22 Apr 2020 12:06:32 +0200 Message-Id: <20200422100636.46357-2-maco@android.com> X-Mailer: git-send-email 2.26.2.303.gf8c07b1a785-goog In-Reply-To: <20200422100636.46357-1-maco@android.com> References: <20200422100636.46357-1-maco@android.com> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org figure_loop_size() calculates the loop size based on the passed in parameters, but at the same time it updates the offset and sizelimit parameters in the loop device configuration. That is a somewhat unexpected side effect of a function with this name, and it is only only needed by one of the two callers of this function - loop_set_status(). Move the lo_offset and lo_sizelimit assignment back into loop_set_status(), and factor out a new function (loop_set_size()) to apply a newly calculated size that has been validated to fit in sector_t, and notify user-space. loop_update_size() is now solely used by loop_set_capacity to compute an updated size, and loop_set_status() uses a combination of functions to validate the loop size, and only apply it later. Signed-off-by: Martijn Coenen --- drivers/block/loop.c | 88 ++++++++++++++++++++++++++++---------------- 1 file changed, 56 insertions(+), 32 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index f1754262fc94..4f5c765c73d8 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -228,23 +228,42 @@ static void __loop_update_dio(struct loop_device *lo, bool dio) blk_mq_unfreeze_queue(lo->lo_queue); } +/** + * loop_set_size - sets device size and notifies userspace + * @lo: struct loop_device to set the size for + * @size: new size of the loop device + * + * Callers must validate that the size passed into this function fits into + * a sector_t. + */ +static void loop_set_size(struct loop_device *lo, loff_t size) +{ + struct block_device *bdev = lo->lo_device; + + set_capacity(lo->lo_disk, size); + bd_set_size(bdev, size << SECTOR_SHIFT); + /* let user-space know about the new size */ + kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); +} + +/** + * loop_update_size - updates device size from the backing file + * @lo: struct loop_device to update the size for + * + * Recomputes the device size from the backing file, and updates the device + * with the new size. + */ static int -figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) +loop_update_size(struct loop_device *lo) { - loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); + loff_t size = get_loop_size(lo, lo->lo_backing_file); sector_t x = (sector_t)size; - struct block_device *bdev = lo->lo_device; if (unlikely((loff_t)x != size)) return -EFBIG; - if (lo->lo_offset != offset) - lo->lo_offset = offset; - if (lo->lo_sizelimit != sizelimit) - lo->lo_sizelimit = sizelimit; - set_capacity(lo->lo_disk, x); - bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9); - /* let user-space know about the new size */ - kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); + + loop_set_size(lo, size); + return 0; } @@ -1040,11 +1059,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, loop_update_rotational(lo); loop_update_dio(lo); - set_capacity(lo->lo_disk, size); - bd_set_size(bdev, size << 9); loop_sysfs_init(lo); - /* let user-space know about the new size */ - kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); + loop_set_size(lo, size); set_blocksize(bdev, S_ISBLK(inode->i_mode) ? block_size(inode->i_bdev) : PAGE_SIZE); @@ -1267,6 +1283,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) kuid_t uid = current_uid(); struct block_device *bdev; bool partscan = false; + bool size_changed = false; + loff_t validated_size; err = mutex_lock_killable(&loop_ctl_mutex); if (err) @@ -1288,6 +1306,14 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (lo->lo_offset != info->lo_offset || lo->lo_sizelimit != info->lo_sizelimit) { + size_t size = get_size(info->lo_offset, info->lo_sizelimit, + lo->lo_backing_file); + if ((loff_t)(sector_t)size != size) { + err = -EFBIG; + goto out_unlock; + } + size_changed = true; + validated_size = size; sync_blockdev(lo->lo_device); kill_bdev(lo->lo_device); } @@ -1295,6 +1321,15 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) /* I/O need to be drained during transfer transition */ blk_mq_freeze_queue(lo->lo_queue); + if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) { + /* If any pages were dirtied after kill_bdev(), try again */ + err = -EAGAIN; + pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", + __func__, lo->lo_number, lo->lo_file_name, + lo->lo_device->bd_inode->i_mapping->nrpages); + goto out_unfreeze; + } + err = loop_release_xfer(lo); if (err) goto out_unfreeze; @@ -1318,22 +1353,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (err) goto out_unfreeze; - if (lo->lo_offset != info->lo_offset || - lo->lo_sizelimit != info->lo_sizelimit) { - /* kill_bdev should have truncated all the pages */ - if (lo->lo_device->bd_inode->i_mapping->nrpages) { - err = -EAGAIN; - pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", - __func__, lo->lo_number, lo->lo_file_name, - lo->lo_device->bd_inode->i_mapping->nrpages); - goto out_unfreeze; - } - if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) { - err = -EFBIG; - goto out_unfreeze; - } - } - + lo->lo_offset = info->lo_offset; + lo->lo_sizelimit = info->lo_sizelimit; memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); lo->lo_file_name[LO_NAME_SIZE-1] = 0; @@ -1357,6 +1378,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) lo->lo_key_owner = uid; } + if (size_changed) + loop_set_size(lo, validated_size); + loop_config_discard(lo); /* update dio if lo_offset or transfer is changed */ @@ -1534,7 +1558,7 @@ static int loop_set_capacity(struct loop_device *lo) if (unlikely(lo->lo_state != Lo_bound)) return -ENXIO; - return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit); + return loop_update_size(lo); } static int loop_set_dio(struct loop_device *lo, unsigned long arg)