linux-kernel - Re: [PATCH] udf: Fix deadlock when converting file from in-ICB one to normal one

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Message-ID: <CAKYAXd9jYMZMht02n=W4T8+hq8hU8owoZk07TbLb-myk52PNKw@mail.gmail.com>
Date:	Sat, 10 Dec 2011 13:40:53 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	Jan Kara <jack@...e.cz>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-fsdevel@...r.kernel.org,
	Matthias Matiak <netzpython@...l-on.us>
Subject: Re: [PATCH] udf: Fix deadlock when converting file from in-ICB one to
 normal one

2011/12/10 Jan Kara <jack@...e.cz>:
> During BKL removal, conversion of files from in-ICB format to normal format got
> broken. We call ->writepage with i_data_sem held but udf_get_block() also
> acquires i_data_sem thus creating A-A deadlock.
>
> We fix the problem by dropping i_data_sem before calling ->writepage() which is
> safe since i_mutex still protects us against any changes in the file. Also fix
> pagelock - i_data_sem lock inversion in udf_expand_file_adinicb() by dropping
> i_data_sem before calling find_or_create_page().
>
> Reported-by: Matthias Matiak <netzpython@...l-on.us>
> Signed-off-by: Jan Kara <jack@...e.cz>
Reviewed-by: Namjae Jeon <linkinjeon@...il.com>
> ---
>  fs/udf/file.c  |    6 +++---
>  fs/udf/inode.c |   20 +++++++++++++++++---
>  2 files changed, 20 insertions(+), 6 deletions(-)
>
>  I plan to merge this fix through my tree soon.
>
> +/*
> + * Expand file stored in ICB to a normal one-block-file
> + *
> + * This function requires i_data_sem for writing and releases it.
> + * This function requires i_mutex held
> + */
>  int udf_expand_file_adinicb(struct inode *inode)
>  {
>        struct page *page;
> @@ -171,6 +177,11 @@ int udf_expand_file_adinicb(struct inode *inode)
>                mark_inode_dirty(inode);
                  up_write(&iinfo->i_data_sem);
Hi Jan.
I do not know if that helps, Would it need here ?
Thanks.
>                return 0;
>        }
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