From: "Jürg Billeter" <j@bitron.ch>
To: Miklos Szeredi <miklos@szeredi.hu>, Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [REGRESSION] fuse: copy_file_range() fails with EIO
Date: Thu, 22 Aug 2024 15:12:17 +0200 [thread overview]
Message-ID: <ea297a16508dbf8ecfa4417cc88eef95b5d697e8.camel@bitron.ch> (raw)
In-Reply-To: <CAJfpegvVc_bZbL1bjcEbEh4+WU=XVS94NMyBPKbcHzAzyxM6_Q@mail.gmail.com>
On Thu, 2024-08-22 at 15:04 +0200, Miklos Szeredi wrote:
> On Sat, 10 Aug 2024 at 17:12, Matthew Wilcox <willy@infradead.org> wrote:
> > That's what I suspected was going wrong -- we're trying to end a read on
> > a folio that is already uptodate. Miklos, what the hell is FUSE doing
> > here?
>
> Ah, this is the fancy page cache replacement done in
> fuse_try_move_page().
>
> I understand how this triggers VM_BUG_ON_FOLIO() in folio_end_read().
>
> What I don't understand is how this results in the -EIO that Jürg
> reported.
I'm not really familiar with this code but it seems `folio_end_read()`
uses xor to update the `PG_uptodate` flag. So if it was already set, it
will incorrectly clear the `PG_uptodate` set, which I guess triggers
the issue.
Jürg
next prev parent reply other threads:[~2024-08-22 13:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-09 15:53 [REGRESSION] fuse: copy_file_range() fails with EIO Jürg Billeter
2024-08-09 16:03 ` Matthew Wilcox
2024-08-09 16:22 ` [PATCH 1/3] fuse: remove call to SetPageError Matthew Wilcox (Oracle)
2024-08-09 16:22 ` [PATCH 2/3] fuse: Use a folio instead of a page Matthew Wilcox (Oracle)
2024-08-09 16:22 ` [PATCH 3/3] fuse: use folio_end_read Matthew Wilcox (Oracle)
2024-08-10 12:24 ` Jürg Billeter
2024-08-20 12:57 ` Jürg Billeter
2024-08-20 13:50 ` Matthew Wilcox
2024-08-22 11:58 ` Miklos Szeredi
2024-08-22 12:25 ` Matthew Wilcox
2024-08-10 5:56 ` [REGRESSION] fuse: copy_file_range() fails with EIO Jürg Billeter
2024-08-10 15:12 ` Matthew Wilcox
2024-08-22 13:04 ` Miklos Szeredi
2024-08-22 13:12 ` Jürg Billeter [this message]
2024-08-22 13:14 ` Miklos Szeredi
2024-08-22 13:32 ` Miklos Szeredi
2024-08-22 14:14 ` Jürg Billeter
2024-08-29 9:27 ` Marcel Ziswiler
2024-08-29 9:30 ` Miklos Szeredi
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