From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AF16C282CE for ; Wed, 13 Feb 2019 07:13:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38392222C0 for ; Wed, 13 Feb 2019 07:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389072AbfBMHNF (ORCPT ); Wed, 13 Feb 2019 02:13:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:48274 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387769AbfBMHNE (ORCPT ); Wed, 13 Feb 2019 02:13:04 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 42BFCAF60; Wed, 13 Feb 2019 07:13:02 +0000 (UTC) Subject: Re: [PATCH v2] scsi: sd: block: Fix regressions in read-only block device handling To: "Martin K. Petersen" , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Jeremy Cline , Oleksii Kurochko , stable@vger.kernel.org References: <20190213025717.20057-1-martin.petersen@oracle.com> From: Hannes Reinecke Message-ID: Date: Wed, 13 Feb 2019 08:13:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20190213025717.20057-1-martin.petersen@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2/13/19 3:57 AM, Martin K. Petersen wrote: > Some devices come online in write protected state and switch to > read-write once they are ready to process I/O requests. These devices > broke with commit 20bd1d026aac ("scsi: sd: Keep disk read-only when > re-reading partition") because we had no way to distinguish between a > user decision to set a block_device read-only and the actual hardware > device being write-protected. > > Because partitions are dropped and recreated on revalidate we are > unable to persist any user-provided policy in hd_struct. Introduce a > bitmap in struct gendisk to track the user configuration. This bitmap > is updated when BLKROSET is called on a given disk or partition. > > A helper function, get_user_ro(), is provided to determine whether the > ioctl has forced read-only state for a given block device. This helper > is used by set_disk_ro() and add_partition() to ensure that both > existing and newly created partitions will get the correct state. > > - If BLKROSET sets a whole disk device read-only, all partitions will > now end up in a read-only state. > > - If BLKROSET sets a given partition read-only, that partition will > remain read-only post revalidate. > > - Otherwise both the whole disk device and any partitions will > reflect the write protect state of the underlying device. > > Cc: Jeremy Cline > Cc: Oleksii Kurochko > Cc: stable@vger.kernel.org # v4.16+ > Reported-by: Oleksii Kurochko > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201221 > Fixes: 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading partition") > Signed-off-by: Martin K. Petersen > > --- > > v2: > - Track user read-only state in a bitmap > > - Work around the regression that caused us to drop user > preferences on revalidate > --- > block/genhd.c | 22 +++++++++++++++++----- > block/ioctl.c | 4 ++++ > block/partition-generic.c | 2 +- > drivers/scsi/sd.c | 4 +--- > include/linux/genhd.h | 2 ++ > 5 files changed, 25 insertions(+), 9 deletions(-) > > diff --git a/block/genhd.c b/block/genhd.c > index 1dd8fd6613b8..34667eb1d3cc 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -1544,19 +1544,31 @@ void set_device_ro(struct block_device *bdev, int flag) > > EXPORT_SYMBOL(set_device_ro); > > +bool get_user_ro(struct gendisk *disk, unsigned int partno) > +{ > + /* Is the user read-only bit set for the whole disk device? */ > + if (test_bit(0, disk->user_ro_bitmap)) > + return true; > + > + /* Is the user read-only bit set for this particular partition? */ > + if (test_bit(partno, disk->user_ro_bitmap)) > + return true; > + > + return false; > +} > +EXPORT_SYMBOL(get_user_ro); > + > void set_disk_ro(struct gendisk *disk, int flag) > { > struct disk_part_iter piter; > struct hd_struct *part; > > - if (disk->part0.policy != flag) { > + if (disk->part0.policy != flag) > set_disk_ro_uevent(disk, flag); > - disk->part0.policy = flag; > - } > > - disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY); > + disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY_PART0); > while ((part = disk_part_iter_next(&piter))) > - part->policy = flag; > + part->policy = get_user_ro(disk, part->partno) ?: flag; > disk_part_iter_exit(&piter); > } > > diff --git a/block/ioctl.c b/block/ioctl.c > index 4825c78a6baa..41206df89485 100644 > --- a/block/ioctl.c > +++ b/block/ioctl.c > @@ -451,6 +451,10 @@ static int blkdev_roset(struct block_device *bdev, fmode_t mode, > return ret; > if (get_user(n, (int __user *)arg)) > return -EFAULT; > + if (n) > + set_bit(bdev->bd_partno, bdev->bd_disk->user_ro_bitmap); > + else > + clear_bit(bdev->bd_partno, bdev->bd_disk->user_ro_bitmap); > set_device_ro(bdev, n); > return 0; > } > diff --git a/block/partition-generic.c b/block/partition-generic.c > index 8e596a8dff32..c6a3c21c2496 100644 > --- a/block/partition-generic.c > +++ b/block/partition-generic.c > @@ -338,7 +338,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno, > queue_limit_discard_alignment(&disk->queue->limits, start); > p->nr_sects = len; > p->partno = partno; > - p->policy = get_disk_ro(disk); > + p->policy = get_user_ro(disk, partno) ?: get_disk_ro(disk); > > if (info) { > struct partition_meta_info *pinfo = alloc_part_info(disk); > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 67cc439b86e4..5dfe37b08d3b 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -2591,10 +2591,8 @@ sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer) > int res; > struct scsi_device *sdp = sdkp->device; > struct scsi_mode_data data; > - int disk_ro = get_disk_ro(sdkp->disk); > int old_wp = sdkp->write_prot; > > - set_disk_ro(sdkp->disk, 0); > if (sdp->skip_ms_page_3f) { > sd_first_printk(KERN_NOTICE, sdkp, "Assuming Write Enabled\n"); > return; > @@ -2632,7 +2630,7 @@ sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer) > "Test WP failed, assume Write Enabled\n"); > } else { > sdkp->write_prot = ((data.device_specific & 0x80) != 0); > - set_disk_ro(sdkp->disk, sdkp->write_prot || disk_ro); > + set_disk_ro(sdkp->disk, sdkp->write_prot); > if (sdkp->first_scan || old_wp != sdkp->write_prot) { > sd_printk(KERN_NOTICE, sdkp, "Write Protect is %s\n", > sdkp->write_prot ? "on" : "off"); > diff --git a/include/linux/genhd.h b/include/linux/genhd.h > index 06c0fd594097..9645c2604465 100644 > --- a/include/linux/genhd.h > +++ b/include/linux/genhd.h > @@ -194,6 +194,7 @@ struct gendisk { > */ > struct disk_part_tbl __rcu *part_tbl; > struct hd_struct part0; > + DECLARE_BITMAP(user_ro_bitmap, DISK_MAX_PARTS); > > const struct block_device_operations *fops; > struct request_queue *queue; > @@ -433,6 +434,7 @@ extern struct block_device *bdget_disk(struct gendisk *disk, int partno); > > extern void set_device_ro(struct block_device *bdev, int flag); > extern void set_disk_ro(struct gendisk *disk, int flag); > +extern bool get_user_ro(struct gendisk *disk, unsigned int partno); > > static inline int get_disk_ro(struct gendisk *disk) > { > Hmm. Can't say I like it. But as we're dropping partitions on revalidate I guess we'll have to do it that way. Oh well. Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)