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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 BD0E0C636CA for ; Fri, 16 Jul 2021 05:49:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A2CB3613E9 for ; Fri, 16 Jul 2021 05:49:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234310AbhGPFws (ORCPT ); Fri, 16 Jul 2021 01:52:48 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:39568 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231961AbhGPFwq (ORCPT ); Fri, 16 Jul 2021 01:52:46 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 199FA22B37; Fri, 16 Jul 2021 05:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1626414591; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=h8PAYPEK4+MS0FrJRkYupjRXBGho7fDC4xEGwlkrTCo=; b=Zyl79cBchiMZFmmY+SmyrA4qyl6PehrsKFOSfz8hYYKCYyR4k+nY+aWXT3UGC2kMkDllrA mqtKZFGwV4TmLd2WI+t95RB6nEgq6h1HmSk0CiF5++hiHyYYi8UP4vh/ZJ6uxEmPJW18v+ ERku03lb/6u/PiZgOHiGwj2Vz7meMdw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1626414591; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=h8PAYPEK4+MS0FrJRkYupjRXBGho7fDC4xEGwlkrTCo=; b=76kMZhfZmqsydbvq64OBPT6Q7a0jTikUzWmU1vufa0uSCC3yCSeIWP9QvUSDCZ63lAyhMw Drl/K9lB/R2X6LAQ== Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id B631E13357; Fri, 16 Jul 2021 05:49:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id MK06Kv4d8WCDNwAAGKfGzw (envelope-from ); Fri, 16 Jul 2021 05:49:50 +0000 Subject: Re: [RFC 2/6] block: add flag for add_disk() completion notation To: Luis Chamberlain , axboe@kernel.dk Cc: bvanassche@acm.org, ming.lei@redhat.com, hch@infradead.org, jack@suse.cz, osandov@fb.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210715202341.2016612-1-mcgrof@kernel.org> <20210715202341.2016612-3-mcgrof@kernel.org> From: Hannes Reinecke Message-ID: Date: Fri, 16 Jul 2021 07:49:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210715202341.2016612-3-mcgrof@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/15/21 10:23 PM, Luis Chamberlain wrote: > Often drivers may have complex setups where it is not > clear if their disk completed their respective *add_disk*() > call. They either have to invent a setting or, they > incorrectly use GENHD_FL_UP. Using GENHD_FL_UP however is > used internally so we know when we can add / remove > partitions safely. We can easily fail along the way > prior to add_disk() completing and still have > GENHD_FL_UP set, so it would not be correct in that case > to call del_gendisk() on the disk. > > Provide a new flag then which allows us to check if > *add_disk*() completed, and conversely just make > del_gendisk() check for this for drivers so that > they can safely call del_gendisk() and we'll figure > it out if it is safe for you to call this. > > Signed-off-by: Luis Chamberlain > --- > block/genhd.c | 8 ++++++++ > include/linux/genhd.h | 11 ++++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/block/genhd.c b/block/genhd.c > index c6c9c196ff27..72703d243b44 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -630,6 +630,8 @@ static int __device_add_disk(struct device *parent, struct gendisk *disk, > if (ret) > goto exit_del_events; > > + disk->flags |= GENHD_FL_DISK_ADDED; > + > return 0; > exit_del_events: > disk_del_events(disk); > @@ -677,6 +679,9 @@ EXPORT_SYMBOL(device_add_disk_no_queue_reg); > * with put_disk(), which should be called after del_gendisk(), if > * __device_add_disk() was used. > * > + * Drivers can safely call this even if they are not sure if the respective > + * __device_add_disk() call succeeded. > + * > * Drivers exist which depend on the release of the gendisk to be synchronous, > * it should not be deferred. > * > @@ -686,6 +691,9 @@ void del_gendisk(struct gendisk *disk) > { > might_sleep(); > > + if (!blk_disk_registered(disk)) > + return; > + > if (WARN_ON_ONCE(!disk->queue)) > return; > > diff --git a/include/linux/genhd.h b/include/linux/genhd.h > index dc07a957c9e1..73024416d2d5 100644 > --- a/include/linux/genhd.h > +++ b/include/linux/genhd.h > @@ -56,6 +56,10 @@ struct partition_meta_info { > * Must not be set for devices which are removed entirely when the > * media is removed. > * > + * ``GENHD_FL_DISK_ADDED`` (0x0002): used to clarify that the > + * respective add_disk*() call completed successfully, so that > + * we know we can safely process del_gendisk() on the disk. > + * > * ``GENHD_FL_CD`` (0x0008): the block device is a CD-ROM-style > * device. > * Affects responses to the ``CDROM_GET_CAPABILITY`` ioctl. > @@ -94,7 +98,7 @@ struct partition_meta_info { > * Used for multipath devices. > */ > #define GENHD_FL_REMOVABLE 0x0001 > -/* 2 is unused (used to be GENHD_FL_DRIVERFS) */ > +#define GENHD_FL_DISK_ADDED 0x0002 > /* 4 is unused (used to be GENHD_FL_MEDIA_CHANGE_NOTIFY) */ > #define GENHD_FL_CD 0x0008 > #define GENHD_FL_UP 0x0010 > @@ -189,6 +193,11 @@ struct gendisk { > #define disk_to_cdi(disk) NULL > #endif > > +static inline bool blk_disk_registered(struct gendisk *disk) > +{ > + return disk && (disk->flags & GENHD_FL_DISK_ADDED); > +} > + > static inline int disk_max_parts(struct gendisk *disk) > { > if (disk->flags & GENHD_FL_EXT_DEVT) > Bah. The flag is named 'DISK_ADDED', and the wrapper 'disk_registered'. Please use the same wording (either 'added' or 'registered') for both to avoid confusion. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer