Re: [PATCH] btrfs: fix disk-io.c/btrfs_read_dev_super with BTRFS_SUPER_MIRROR_MAX to control the loops

cwillu
2012-09-10T07:24:49Z

On Mon, Sep 10, 2012 at 12:38 AM, Wang Sheng-Hui <shhuiw@gmail.com> wrote:
> To check the duplicated super blocks, use BTRFS_SUPER_MIRROR_MAX
> as the loops limit.
>
> Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
> ---
> fs/btrfs/disk-io.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 22e98e0..a431144 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2723,7 +2723,7 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
> * So, we need to add a special mount option to scan for
> * later supers, using BTRFS_SUPER_MIRROR_MAX instead
> */
> - for (i = 0; i < 1; i++) {
> + for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
> bytenr = btrfs_sb_offset(i);
> if (bytenr + 4096 >= i_size_read(bdev->bd_inode))
> break;
> --
> 1.7.1
>
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Please fix the comment as well; if we check all the supers, then
mounting as btrfs _will_ succeed after a different (non-btrfs)
filesystem is created on the partition/device, pretty much
guaranteeing it will be corrupted.