Re: [PATCH 6/7] Add support for recovery for a raid5 btrfs profiles.

[Daniel Kiper]

On Tue, Apr 24, 2018 at 09:13:15PM +0200, Goffredo Baroncelli wrote:
> Signed-off-by: Goffredo Baroncelli <address@hidden>
> ---
>  grub-core/fs/btrfs.c | 206 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 199 insertions(+), 7 deletions(-)
>
> diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
> index 697322125..5c76a68f3 100644
> --- a/grub-core/fs/btrfs.c
> +++ b/grub-core/fs/btrfs.c
> @@ -29,6 +29,7 @@
>  #include <minilzo.h>
>  #include <grub/i18n.h>
>  #include <grub/btrfs.h>
> +#include <grub/crypto.h>
>
>  GRUB_MOD_LICENSE ("GPLv3+");
>
> @@ -661,9 +662,180 @@ btrfs_read_from_chunk (struct grub_btrfs_data *data,
>      err = grub_disk_read (dev->disk, paddr >> GRUB_DISK_SECTOR_BITS,
>                         paddr & (GRUB_DISK_SECTOR_SIZE - 1),
>                         csize, buf);
> +    grub_dprintf ("btrfs", "reading paddr 0x%" PRIxGRUB_UINT64_T "\n", 
> paddr);
>      return err;
>  }
>
> +struct raid56_buffer {
> +  void *buf;
> +  int  ok;

What ok is?

> +};
> +
> +static void
> +rebuild_raid5 (struct raid56_buffer *buffers, grub_uint64_t nstripes,
> +               grub_uint64_t csize)
> +{
> +  grub_uint64_t target, i;

grub_uint64_t target = 0, i;

> +  target = 0;

...then you can drop this.

> +  while (buffers[target].ok && target < nstripes)
> +    ++target;
> +
> +  if (target == nstripes)
> +    {
> +      grub_dprintf ("btrfs", "called rebuild_raid5(), but all disks are 
> OK\n");
> +      return;
> +    }
> +
> +  grub_dprintf ("btrfs", "rebuilding raid5 stripe #%" PRIuGRUB_UINT64_T "\n",
> +             target);
> +  for (i = 0; i < nstripes ; i++)
> +    if (i != target)
> +      grub_crypto_xor (buffers[target].buf, buffers[target].buf, 
> buffers[i].buf,
> +                       csize);
> +}
> +
> +static void
> +rebuild_raid6 (struct raid56_buffer *buffers, grub_uint64_t nstripes,
> +               grub_uint64_t csize, grub_uint64_t parities_pos, void *dest,
> +               grub_uint64_t stripen)
> +
> +{
> +  (void)buffers;
> +  (void)nstripes;
> +  (void)csize;
> +  (void)parities_pos;
> +  (void)dest;
> +  (void)stripen;
> +  grub_dprintf ("btrfs", "called rebuild_raid6(), NOT IMPLEMENTED\n");

Could you add this function in next patch and print the relevant message
below directly instead from rebuild_raid6()?

> +}
> +
> +static grub_err_t
> +raid56_read_retry (struct grub_btrfs_data *data,
> +                struct grub_btrfs_chunk_item *chunk,
> +                grub_uint64_t stripe_offset, grub_uint64_t stripen,
> +                grub_uint64_t csize, void *buf, grub_uint64_t parities_pos)
> +{
> +
> +  struct raid56_buffer *buffers = NULL;
> +  grub_uint64_t nstripes = grub_le_to_cpu16 (chunk->nstripes);
> +  grub_uint64_t chunk_type = grub_le_to_cpu64 (chunk->type);
> +  grub_err_t ret = GRUB_ERR_NONE;
> +  grub_uint64_t i, failed_devices;
> +
> +  buffers = grub_zalloc (sizeof(struct raid56_buffer)* nstripes);

... sizeof (*buffers) * nstripes ...

> +  if (!buffers)
> +    {
> +      ret = GRUB_ERR_OUT_OF_MEMORY;
> +      goto cleanup;
> +    }
> +
> +  for (i = 0 ; i < nstripes ; i++)

for (i = 0; i < nstripes; i++)

> +    {
> +      buffers[i].buf = grub_zalloc(csize);

... grub_zalloc (csize);

> +      if (!buffers[i].buf)
> +     {
> +       ret = GRUB_ERR_OUT_OF_MEMORY;
> +       goto cleanup;
> +     }
> +    }
> +
> +  for (i = 0 ; i < nstripes ; i++)

Ditto.

> +    {
> +      struct grub_btrfs_chunk_stripe *stripe;
> +      grub_disk_addr_t paddr;
> +      grub_device_t dev;
> +      grub_err_t err2;
> +
> +      stripe = (struct grub_btrfs_chunk_stripe *) (chunk + 1);
> +      stripe += i;
> +
> +      paddr = grub_le_to_cpu64 (stripe->offset) + stripe_offset;
> +      grub_dprintf ("btrfs", "reading paddr %" PRIxGRUB_UINT64_T
> +                    " from stripe ID %" PRIxGRUB_UINT64_T "\n", paddr,
> +                    stripe->device_id);
> +
> +      /* FIXME: rescan the devices */
> +      dev = find_device (data, stripe->device_id);
> +      if (!dev)
> +     {
> +       buffers[i].ok = 0;
> +       grub_dprintf ("btrfs", "stripe %" PRIuGRUB_UINT64_T " FAILED (dev ID 
> %"
> +                     PRIxGRUB_UINT64_T ")\n", i, stripe->device_id);
> +       continue;
> +        }

Something is wrong with aligment.

> +      err2 = grub_disk_read (dev->disk, paddr >> GRUB_DISK_SECTOR_BITS,
> +                          paddr & (GRUB_DISK_SECTOR_SIZE - 1),
> +                          csize, buffers[i].buf);
> +      if (err2 == GRUB_ERR_NONE)
> +     {
> +       buffers[i].ok = 1;
> +       grub_dprintf ("btrfs", "stripe %" PRIuGRUB_UINT64_T " Ok (dev ID %"
> +                     PRIxGRUB_UINT64_T ")\n", i, stripe->device_id);
> +     }
> +      else
> +     {
> +       buffers[i].ok = 0;
> +       grub_dprintf ("btrfs", "stripe %" PRIuGRUB_UINT64_T
> +                     " FAILED (dev ID %" PRIxGRUB_UINT64_T ")\n", i,
> +                     stripe->device_id);
> +     }
> +    }
> +
> +  failed_devices = 0;
> +  for (i = 0 ; i < nstripes ; i++)

Ditto.

> +    if (!buffers[i].ok)
> +      ++failed_devices;
> +  if (failed_devices > 1 && (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID5))
> +    {
> +      grub_dprintf ("btrfs",
> +                 "not enough disks for raid5: total %" PRIuGRUB_UINT64_T
> +                 ", missing %" PRIuGRUB_UINT64_T "\n",
> +                 nstripes, failed_devices);
> +      ret = GRUB_ERR_READ_ERROR;
> +      goto cleanup;
> +    }
> +  else if (failed_devices > 2 && (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID6))
> +    {
> +      grub_dprintf ("btrfs",
> +                 "not enough disks for raid6: total %" PRIuGRUB_UINT64_T
> +                 ", missing %" PRIuGRUB_UINT64_T "\n",
> +                 nstripes, failed_devices);
> +      ret = GRUB_ERR_READ_ERROR;
> +      goto cleanup;
> +    }

This piece of code should be introduced in next patch.

> +  else
> +    {
> +      grub_dprintf ("btrfs",
> +                    "enough disks for raid5/6 rebuilding: total %"
> +                 PRIuGRUB_UINT64_T ", missing %" PRIuGRUB_UINT64_T "\n",
> +                    nstripes, failed_devices);
> +    }
> +
> +  /* if these are enough, try to rebuild the data */
> +  if (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID5)
> +    {
> +      rebuild_raid5 (buffers, nstripes, csize);
> +      grub_memcpy (buf, buffers[stripen].buf, csize);
> +    }
> +  else
> +    {
> +      rebuild_raid6 (buffers, nstripes, csize, parities_pos, buf, stripen);

Please print not implemented messaged here instead of rebuild_raid6() call.

> +    }
> +
> +cleanup:

Please add one space before the label.

> +  if (buffers)
> +    {
> +      for (i = 0 ; i < nstripes ; i++)

Ditto.

> +     if (buffers[i].buf)
> +       grub_free(buffers[i].buf);
> +      grub_free(buffers);
> +    }
> +
> +  return ret;
> +}
> +
>  static grub_err_t
>  grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
>                        void *buf, grub_size_t size, int recursion_depth)
> @@ -741,6 +913,11 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, 
> grub_disk_addr_t addr,
>       grub_uint16_t nstripes;
>       unsigned redundancy = 1;
>       unsigned i, j;
> +        int is_raid56;

Incorrect aligment.

> +     grub_uint64_t parities_pos = 0;
> +
> +        is_raid56 = !!(grub_le_to_cpu64 (chunk->type) &
> +                 (GRUB_BTRFS_CHUNK_TYPE_RAID5|GRUB_BTRFS_CHUNK_TYPE_RAID6));

Do we need GRUB_BTRFS_CHUNK_TYPE_RAID6 here? Or maybe this
should be introduced by next patch?

>       if (grub_le_to_cpu64 (chunk->size) <= off)
>         {
> @@ -844,9 +1021,10 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, 
> grub_disk_addr_t addr,
>               }
>
>             stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low);
> -
>             high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen);
>             grub_divmod64 (high + stripen, nstripes, &stripen);
> +           grub_divmod64 (high + nstripes - nparities, nstripes,
> +                          &parities_pos);
>
>             stripe_offset = low + chunk_stripe_length * high;
>             csize = chunk_stripe_length - low;
> @@ -881,12 +1059,26 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, 
> grub_disk_addr_t addr,
>           grub_dprintf ("btrfs", "reading laddr 0x%" PRIxGRUB_UINT64_T "\n",
>                         addr);
>
> -         err = GRUB_ERR_NONE + 1;
> -         for (i = 0; i < redundancy && err != GRUB_ERR_NONE; i++)
> -              err = btrfs_read_from_chunk (data, chunk, stripen,
> -                                           stripe_offset,
> -                                           i,     /* redundancy */
> -                                           csize, buf);
> +         if (!is_raid56)
> +           {
> +             err = GRUB_ERR_NONE+1;

What?

Daniel