Re: [PATCH v2] ubi: Make recover_peb power cut aware

["Jörg Pfähler" <pfaehler@isse.de>]

Reviewed-by: Jörg Pfähler <pfaehler@isse.de>

Am Dienstag, 21. Juni 2016, 00:31:50 CEST schrieb Richard Weinberger:
> recover_peb() was never power cut aware,
> if a power cut happened right after writing the VID header
> upon next attach UBI would blindly use the new partial written
> PEB and all data from the old PEB is lost.
> 
> In order to make recover_peb() power cut aware, write the new
> VID with a proper crc and copy_flag set such that the UBI attach
> process will detect whether the new PEB is completely written
> or not.
> We cannot directly use ubi_eba_atomic_leb_change() since we'd
> have to unlock the LEB which is facing a write error.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Jörg Pfähler <pfaehler@isse.de>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>  drivers/mtd/ubi/eba.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
> index 5780dd1..ebf5172 100644
> --- a/drivers/mtd/ubi/eba.c
> +++ b/drivers/mtd/ubi/eba.c
> @@ -575,6 +575,7 @@ static int recover_peb(struct ubi_device *ubi, int pnum,
> int vol_id, int lnum, int err, idx = vol_id2idx(ubi, vol_id), new_pnum,
> data_size, tries = 0; struct ubi_volume *vol = ubi->volumes[idx];
>  	struct ubi_vid_hdr *vid_hdr;
> +	uint32_t crc;
> 
>  	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
>  	if (!vid_hdr)
> @@ -599,14 +600,8 @@ retry:
>  		goto out_put;
>  	}
> 
> -	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
> -	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
> -	if (err) {
> -		up_read(&ubi->fm_eba_sem);
> -		goto write_error;
> -	}
> +	ubi_assert(vid_hdr->vol_type == UBI_VID_DYNAMIC);
> 
> -	data_size = offset + len;
>  	mutex_lock(&ubi->buf_mutex);
>  	memset(ubi->peb_buf + offset, 0xFF, len);
> 
> @@ -621,6 +616,19 @@ retry:
> 
>  	memcpy(ubi->peb_buf + offset, buf, len);
> 
> +	data_size = offset + len;
> +	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
> +	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
> +	vid_hdr->copy_flag = 1;
> +	vid_hdr->data_size = cpu_to_be32(data_size);
> +	vid_hdr->data_crc = cpu_to_be32(crc);
> +	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
> +	if (err) {
> +		mutex_unlock(&ubi->buf_mutex);
> +		up_read(&ubi->fm_eba_sem);
> +		goto write_error;
> +	}
> +
>  	err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
>  	if (err) {
>  		mutex_unlock(&ubi->buf_mutex);


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Jörg Pfähler
Lehrstuhl für Softwaretechnik
Institut für Software and Systems Engineering
Universität Augsburg

Universitätsstr. 6a, Raum 3014
tel:      (+49) 821/598-2229
e-mail:   pfaehler@isse.de<mailto:pfaehler@isse.de>
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