[Cluster-devel] [GFS2 PATCH 3/4] gfs2: add a helper function to get_log_header that can be used elsewhere

[Andreas Gruenbacher]

On Tue, 16 Oct 2018 at 06:23, Abhi Das <adas at redhat.com> wrote:
> Move and re-order the error checks and hash/crc computations into another
> function __get_log_header() so it can be used in scenarios where buffer_heads
> are not being used for the log header.
>
> Signed-off-by: Abhi Das <adas at redhat.com>

Reviewed-by: Andreas Gruenbacher <agruenba at redhat.com>

Thanks,
Andreas

> ---
>  fs/gfs2/recovery.c | 53 ++++++++++++++++++++++++++++++++---------------------
>  fs/gfs2/recovery.h |  2 ++
>  2 files changed, 34 insertions(+), 21 deletions(-)
>
> diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c
> index b0717a0..2dac430 100644
> --- a/fs/gfs2/recovery.c
> +++ b/fs/gfs2/recovery.c
> @@ -120,6 +120,35 @@ void gfs2_revoke_clean(struct gfs2_jdesc *jd)
>         }
>  }
>
> +int __get_log_header(struct gfs2_sbd *sdp, const struct gfs2_log_header *lh,
> +                    unsigned int blkno, struct gfs2_log_header_host *head)
> +{
> +       u32 hash, crc;
> +
> +       if (lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
> +           lh->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH) ||
> +           (blkno && be32_to_cpu(lh->lh_blkno) != blkno))
> +               return 1;
> +
> +       hash = crc32(~0, lh, LH_V1_SIZE - 4);
> +       hash = ~crc32_le_shift(hash, 4); /* assume lh_hash is zero */
> +
> +       if (be32_to_cpu(lh->lh_hash) != hash)
> +               return 1;
> +
> +       crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
> +                    sdp->sd_sb.sb_bsize - LH_V1_SIZE - 4);
> +
> +       if ((lh->lh_crc != 0 && be32_to_cpu(lh->lh_crc) != crc))
> +               return 1;
> +
> +       head->lh_sequence = be64_to_cpu(lh->lh_sequence);
> +       head->lh_flags = be32_to_cpu(lh->lh_flags);
> +       head->lh_tail = be32_to_cpu(lh->lh_tail);
> +       head->lh_blkno = be32_to_cpu(lh->lh_blkno);
> +
> +       return 0;
> +}
>  /**
>   * get_log_header - read the log header for a given segment
>   * @jd: the journal
> @@ -137,36 +166,18 @@ void gfs2_revoke_clean(struct gfs2_jdesc *jd)
>  static int get_log_header(struct gfs2_jdesc *jd, unsigned int blk,
>                           struct gfs2_log_header_host *head)
>  {
> -       struct gfs2_log_header *lh;
> +       struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
>         struct buffer_head *bh;
> -       u32 hash, crc;
>         int error;
>
>         error = gfs2_replay_read_block(jd, blk, &bh);
>         if (error)
>                 return error;
> -       lh = (void *)bh->b_data;
> -
> -       hash = crc32(~0, lh, LH_V1_SIZE - 4);
> -       hash = ~crc32_le_shift(hash, 4);  /* assume lh_hash is zero */
> -
> -       crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
> -                    bh->b_size - LH_V1_SIZE - 4);
> -
> -       error = lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
> -               lh->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH) ||
> -               be32_to_cpu(lh->lh_blkno) != blk ||
> -               be32_to_cpu(lh->lh_hash) != hash ||
> -               (lh->lh_crc != 0 && be32_to_cpu(lh->lh_crc) != crc);
>
> +       error = __get_log_header(sdp, (const struct gfs2_log_header *)bh->b_data,
> +                                blk, head);
>         brelse(bh);
>
> -       if (!error) {
> -               head->lh_sequence = be64_to_cpu(lh->lh_sequence);
> -               head->lh_flags = be32_to_cpu(lh->lh_flags);
> -               head->lh_tail = be32_to_cpu(lh->lh_tail);
> -               head->lh_blkno = be32_to_cpu(lh->lh_blkno);
> -       }
>         return error;
>  }
>
> diff --git a/fs/gfs2/recovery.h b/fs/gfs2/recovery.h
> index 11fdfab..943a67c 100644
> --- a/fs/gfs2/recovery.h
> +++ b/fs/gfs2/recovery.h
> @@ -31,6 +31,8 @@ extern int gfs2_find_jhead(struct gfs2_jdesc *jd,
>                     struct gfs2_log_header_host *head);
>  extern int gfs2_recover_journal(struct gfs2_jdesc *gfs2_jd, bool wait);
>  extern void gfs2_recover_func(struct work_struct *work);
> +extern int __get_log_header(struct gfs2_sbd *sdp, const struct gfs2_log_header *lh,
> +                           unsigned int blkno, struct gfs2_log_header_host *head);
>
>  #endif /* __RECOVERY_DOT_H__ */
>
> --
> 2.4.11
>