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From: Max Kellermann <mk@cm4all.com>
To: David Howells <dhowells@redhat.com>
Cc: Max Kellermann <mk@cm4all.com>,
	linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: fscache corruption in Linux 5.17?
Date: Tue, 19 Apr 2022 18:06:19 +0200	[thread overview]
Message-ID: <Yl7d++G25sNXIR+p@rabbit.intern.cm-ag> (raw)
In-Reply-To: <507518.1650383808@warthog.procyon.org.uk>

On 2022/04/19 17:56, David Howells <dhowells@redhat.com> wrote:
> This is weird.  It looks like content got slid down by 31 bytes and 31 zero
> bytes got added at the end.  I'm not sure how fscache would achieve that -
> nfs's implementation should only be dealing with pages.

Did you read this part of my email?:

On 2022/04/12 17:10, Max Kellermann <max@rabbit.intern.cm-ag> wrote:
> The corruption can be explained by WordPress commit
> https://github.com/WordPress/WordPress/commit/07855db0ee8d5cff2 which
> makes the file 31 bytes longer (185055 -> 185086).  The "broken" web
> server sees the new contents until offset 184320 (= 45 * 4096), but
> sees the old contents from there on; followed by 31 null bytes
> (because the kernel reads past the end of the cache?).

My theory was that fscache shows a mix of old and new pages after the
file was modified.  Does this make sense?

Is there anything I can do to give you data from this server's cache?

  reply	other threads:[~2022-04-19 16:06 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-12 15:10 fscache corruption in Linux 5.17? Max Kellermann
2022-04-16 11:38 ` Thorsten Leemhuis
2022-04-16 19:55   ` Max Kellermann
2022-04-19 13:02 ` David Howells
2022-04-19 14:18   ` Max Kellermann
2022-04-19 15:23     ` [Linux-cachefs] " David Wysochanski
2022-04-19 16:17   ` David Howells
2022-04-19 16:41     ` Max Kellermann
2022-04-19 16:47     ` David Howells
2022-04-19 15:56 ` David Howells
2022-04-19 16:06   ` Max Kellermann [this message]
2022-04-19 16:42   ` David Howells
2022-04-19 18:01     ` Max Kellermann
2022-04-19 21:27     ` Max Kellermann
2022-04-20 13:55     ` David Howells
2022-05-04  8:38       ` Max Kellermann
2022-05-31  8:35       ` David Howells
2022-05-31  8:41         ` Max Kellermann
2022-05-31  9:13         ` David Howells
2022-06-20  7:11           ` Thorsten Leemhuis

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