Re: [dm-devel] [stable][PATCH < 2.6.19] Fix data corruption withdm-crypt over RAID5

From: Piet Delaney
Date: Wed Jan 17 2007 - 03:44:44 EST


On Sat, 2006-12-02 at 03:27 +0100, Christophe Saout wrote:

Hi Christophe:

I'm wondering about trying out your patch with dm-crypt on 2.6.12.
The code in drivers/md/dm-crypt.c`crypt_endio() appears to be the same.

Is there a reason that this isn't necessary or would be a bad idea.
Looks like the existing code isn't checking the BIO_UPTODATE flag
before doing the bio_put(). Looks the the second part of not calling
kcryptd_queue_io() and forwarding the processing to the cryptd is
effectively the same. The 1st change will set error if BIO_UPTODATE
isn't set and that will cause the 2nd change to skip calling
kcryptd_queue_io().

I'm not sure about the change in the arg to bio_data_dir()
changing from bio to io->bio. Perhaps they are equivalent;
care to comment on that.

Unless I hear otherwise I'll try it out Tomorrow.

-piet

> Fix corruption issue with dm-crypt on top of software raid5. Cancelled
> readahead bio's that report no error, just have BIO_UPTODATE cleared
> were reported as successful reads to the higher layers (and leaving
> random content in the buffer cache). Already fixed in 2.6.19.
>
> Signed-off-by: Christophe Saout <christophe@xxxxxxxx>
>
>
> --- linux-2.6.18.orig/drivers/md/dm-crypt.c 2006-09-20 05:42:06.000000000 +0200
> +++ linux-2.6.18/drivers/md/dm-crypt.c 2006-12-02 03:03:36.000000000 +0100
> @@ -717,13 +717,15 @@
> if (bio->bi_size)
> return 1;
>
> + if (!bio_flagged(bio, BIO_UPTODATE) && !error)
> + error = -EIO;
> +
> bio_put(bio);
>
> /*
> * successful reads are decrypted by the worker thread
> */
> - if ((bio_data_dir(bio) == READ)
> - && bio_flagged(bio, BIO_UPTODATE)) {
> + if (bio_data_dir(io->bio) == READ && !error) {
> kcryptd_queue_io(io);
> return 0;
> }
>
>
> --
> dm-devel mailing list
> dm-devel@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/dm-devel
--
Piet Delaney Phone: (408) 200-5256
Blue Lane Technologies Fax: (408) 200-5299
10450 Bubb Rd.
Cupertino, Ca. 95014 Email: piet@xxxxxxxxxxxx

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