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From: Matthew Wilcox <willy@infradead.org>
To: Richard Weinberger <richard@nod.at>
Cc: linux-mtd <linux-mtd@lists.infradead.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 4/4] ubifs: Convert do_writepage() to take a folio
Date: Tue, 6 Jun 2023 13:32:43 +0100	[thread overview]
Message-ID: <ZH8na21G0W8kmY5r@casper.infradead.org> (raw)
In-Reply-To: <406990820.3686390.1686032035024.JavaMail.zimbra@nod.at>

On Tue, Jun 06, 2023 at 08:13:55AM +0200, Richard Weinberger wrote:
> Matthew,
> 
> ----- Ursprüngliche Mail -----
> > Von: "Matthew Wilcox" <willy@infradead.org>
> > len is folio_size(), which is not 0.
> > 
> >        len = offset_in_folio(folio, i_size);
> 
> offset_in_folio(folio, i_size) can give 0.

Oh!  There is a bug, because it shouldn't get here!

        /* Is the folio fully inside i_size? */
        if (folio_pos(folio) + len < i_size) {

should be:

        /* Is the folio fully inside i_size? */
        if (folio_pos(folio) + len <= i_size) {

right?  Consider a file with i_size 4096.  its single-page folio will
have a pos of 0 and a length of 4096.  so it should be written back by
the first call to do_writepage(), not the case where the folio straddles
i_size.


  reply	other threads:[~2023-06-06 12:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-05 16:50 [PATCH 0/4] ubifs: Convert writeback to use folios Matthew Wilcox (Oracle)
2023-06-05 16:50 ` [PATCH 1/4] ubifs: Convert from writepage to writepages Matthew Wilcox (Oracle)
2023-06-06 14:37   ` Zhihao Cheng
2023-06-07 14:11     ` Zhihao Cheng
2023-06-05 16:50 ` [PATCH 2/4] ubifs: Convert ubifs_writepage to use a folio Matthew Wilcox (Oracle)
2023-06-07 14:48   ` Zhihao Cheng
2023-06-05 16:50 ` [PATCH 3/4] ubifs: Use a folio in do_truncation() Matthew Wilcox (Oracle)
2023-06-05 17:05   ` Matthew Wilcox
2023-06-08 14:31     ` Zhihao Cheng
2023-06-05 16:50 ` [PATCH 4/4] ubifs: Convert do_writepage() to take a folio Matthew Wilcox (Oracle)
2023-06-05 19:28   ` kernel test robot
2023-06-05 21:37   ` Richard Weinberger
2023-06-06  3:22     ` Matthew Wilcox
2023-06-06  6:13       ` Richard Weinberger
2023-06-06 12:32         ` Matthew Wilcox [this message]
2023-06-06 13:41           ` Richard Weinberger
2023-06-05 23:29   ` kernel test robot
2023-06-08 15:09   ` Zhihao Cheng

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