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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>, <stable@vger.kernel.org>
Subject: Re: [PATCH] ext4: Fix crash during online resizing
Date: Mon, 11 Feb 2019 13:43:35 -0500	[thread overview]
Message-ID: <20190211184335.GN23000@mit.edu> (raw)
In-Reply-To: <20190124162606.9686-1-jack@suse.cz>

On Thu, Jan 24, 2019 at 05:26:06PM +0100, Jan Kara wrote:
> When computing maximum size of filesystem possible with given number of
> group descriptor blocks, we forget to include s_first_data_block into
> the number of blocks. Thus for filesystems with non-zero
> s_first_data_block it can happen that computed maximum filesystem size
> is actually lower than current filesystem size which confuses the code
> and eventually leads to a BUG_ON in ext4_alloc_group_tables() hitting on
> flex_gd->count == 0. The problem can be reproduced like:
> 
> truncate -s 100g /tmp/image
> mkfs.ext4 -b 1024 -E resize=262144 /tmp/image 32768
> mount -t ext4 -o loop /tmp/image /mnt
> resize2fs /dev/loop0 262145
> resize2fs /dev/loop0 300000
> 
> Fix the problem by properly including s_first_data_block into the
> computed number of filesystem blocks.
> 
> CC: stable@vger.kernel.org
> Fixes: 1c6bd7173d66 "ext4: convert file system to meta_bg if needed..."
> Signed-off-by: Jan Kara <jack@suse.cz>

Thanks, applied.

					- Ted

      reply	other threads:[~2019-02-11 18:43 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-24 16:26 [PATCH] ext4: Fix crash during online resizing Jan Kara
2019-02-11 18:43 ` Theodore Y. Ts'o [this message]

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