From: Mikulas Patocka <mpatocka@redhat.com>
To: Hugh Dickins <hughd@google.com>
Cc: Lukas Czerner <lczerner@redhat.com>,
Zdenek Kabelac <zkabelac@redhat.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: unusual behavior of loop dev with backing file in tmpfs
Date: Wed, 12 Jan 2022 07:29:11 -0500 (EST) [thread overview]
Message-ID: <alpine.LRH.2.02.2201120725500.27581@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <5e66a9-4739-80d9-5bb5-cbe2c8fef36@google.com>
On Tue, 11 Jan 2022, Hugh Dickins wrote:
> But what is asynchronously reading /dev/loop0 (instantiating pages
> initially, and reinstantiating them after blkdiscard)? I assume it's
> some block device tracker, trying to read capacity and/or partition
> table; whether from inside or outside the kernel, I expect you'll
> guess much better than I can.
>
> Hugh
That's udev. It reads filesystem signature on every block device, so that
it can create symlinks in /dev/disk/by-uuid.
If you open the block device for write and close it, udev will re-scan it.
Mikulas
next prev parent reply other threads:[~2022-01-12 12:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-26 7:51 unusual behavior of loop dev with backing file in tmpfs Lukas Czerner
2022-01-12 4:28 ` Hugh Dickins
2022-01-12 12:29 ` Mikulas Patocka [this message]
2022-01-12 17:19 ` Darrick J. Wong
2022-01-12 17:46 ` Matthew Wilcox
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