From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs-progs: check/lowmem: Reset path in repair mode to avoid incorrect item from being passed to lowmem check.
Date: Wed, 5 Jun 2019 18:08:33 +0200 [thread overview]
Message-ID: <20190605160833.GC9896@twin.jikos.cz> (raw)
In-Reply-To: <20190517140003.32285-1-wqu@suse.com>
On Fri, May 17, 2019 at 10:00:03PM +0800, Qu Wenruo wrote:
> In lowmem mode, we check fs roots and free space cache by iterating
> each root item and inode item, using btrfs_next_item() and a path
> pointing to the root tree.
>
> However in repair mode, check_fs_root() can modify the fs root, thus
> CoWs the tree root, and the old path in check_fs
>
> It could lead to strange behavior, e.g. after repairing a fs tree, the
> path can point to a fs tree.
> Since no ROOT_ITEM exists in fs tree, all remaining trees are skipped in
> repair mode.
>
> This bug exists from the early time of lowmem mode repair, and is only
> exposed by recent free space inode check code. (Fs tree inodes are
> passed to free space inode check, causing false alerts and repair
> failure).
>
> Signed-off-by: Qu Wenruo <wqu@suse.com>
I'll add it to devel, however the lowmem mode of test-check does not
work now, so can't really test it.
next prev parent reply other threads:[~2019-06-05 16:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-17 14:00 [PATCH] btrfs-progs: check/lowmem: Reset path in repair mode to avoid incorrect item from being passed to lowmem check Qu Wenruo
2019-06-05 16:08 ` David Sterba [this message]
2019-06-06 3:52 ` Qu Wenruo
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