From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
Naohiro Aota <naohiro.aota@wdc.com>,
linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 3/9] block: unhash the whole device inode earlier
Date: Thu, 22 Jul 2021 15:12:27 +0200 [thread overview]
Message-ID: <20210722131227.GA27213@lst.de> (raw)
In-Reply-To: <YPkqHjNQpgvbUgBr@T590>
On Thu, Jul 22, 2021 at 04:19:42PM +0800, Ming Lei wrote:
> > goto bdput;
> > - if ((disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP)
> > + if (disk->flags & GENHD_FL_HIDDEN)
>
> But del_gendisk() can be called just between bdget() and checking GENHD_FL_UP.
>
> And not see difference by moving remove_inode_hash() with disk open_mutex held.
The difference is not about having the open_mutex held, but about doing
it earlier.
The only check that matters is the GENHD_FL_UP check in blkdev_get_by_dev.
The earlier check just reduces the amount of work we're doing for a disk
already being delete. With the early unhash there is no need for that
check as we won't even find the inode for a disk in del_gendisk. We still
need the non-racy check under the lock, but the patch doesn't touch that
one.
Maybe I need to split this into two patches and improve the commit log.
next prev parent reply other threads:[~2021-07-22 13:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 7:53 fixes and cleanups for block_device refcounting v2 Christoph Hellwig
2021-07-22 7:53 ` [PATCH 1/9] block: delay freeing the gendisk Christoph Hellwig
2021-07-22 7:53 ` [PATCH 2/9] block: assert the locking state in delete_partition Christoph Hellwig
2021-07-22 18:38 ` Chaitanya Kulkarni
2021-07-22 7:53 ` [PATCH 3/9] block: unhash the whole device inode earlier Christoph Hellwig
2021-07-22 8:19 ` Ming Lei
2021-07-22 13:12 ` Christoph Hellwig [this message]
2021-07-22 7:53 ` [PATCH 4/9] block: allocate bd_meta_info later in add_partitions Christoph Hellwig
2021-07-22 8:32 ` Ming Lei
2021-07-22 7:53 ` [PATCH 5/9] block: change the refcounting for partitions Christoph Hellwig
2021-07-22 8:41 ` Ming Lei
2021-07-22 13:12 ` Christoph Hellwig
2021-07-22 7:53 ` [PATCH 6/9] btrfs: store a block_device in struct btrfs_ordered_extent Christoph Hellwig
2021-07-22 12:58 ` David Sterba
2021-07-22 13:04 ` Christoph Hellwig
2021-07-22 7:54 ` [PATCH 7/9] loop: don't grab a reference to the block device Christoph Hellwig
2021-07-22 8:57 ` Ming Lei
2021-07-22 18:40 ` Chaitanya Kulkarni
2021-07-22 7:54 ` [PATCH 8/9] block: remove bdgrab Christoph Hellwig
2021-07-22 7:54 ` [PATCH 9/9] block: remove bdput Christoph Hellwig
2021-07-22 18:40 ` Chaitanya Kulkarni
2021-07-28 1:39 ` fixes and cleanups for block_device refcounting v2 Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210722131227.GA27213@lst.de \
--to=hch@lst.de \
--cc=axboe@kernel.dk \
--cc=dsterba@suse.com \
--cc=josef@toxicpanda.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=naohiro.aota@wdc.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).