On Mon, Jun 03, 2019 at 12:05:04PM +0300, Nikolay Borisov wrote:
> Signed-off-by: Nikolay Borisov <[email protected]>
> ---
> fs/btrfs/volumes.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/volumes.h | 2 +
> 2 files changed, 100 insertions(+)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 776f5c7ca7c5..b130f465ca6d 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -5907,6 +5907,104 @@ static bool need_full_stripe(enum btrfs_map_op op)
> return (op == BTRFS_MAP_WRITE || op == BTRFS_MAP_GET_READ_MIRRORS);
> }
>
> +/*
> + * btrfs_io_geometry - calculates the geomery of a particular (address, len)
> + * tuple. This information is used to calculate how big a
> + * particular bio can get before it straddles a stripe.
> + *
> + * @fs_info - The omnipresent btrfs structure
> + * @logical - Address that we want to figure out the geometry of
> + * @len - The length of IO we are going to perform, starting at
> @logical
> + * @op - Type of operation - Write or Read
> + * @io_geom - Pointer used to return values
> + *
> + * Returns < 0 in case a chunk for the given logical address cannot be found,
> + * usually shouldn't happen unless @logical is corrupted, 0 otherwise.
> + */
> +int btrfs_io_geometry(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
> + u64 logical, u64 len, struct btrfs_io_geometry *io_geom)
> +{
I think the function name lacks the descriptivity what it does, besides
that it also collides with the structure name.
> + struct extent_map *em;
> + struct map_lookup *map;
> + u64 offset;
> + u64 stripe_offset;
> + u64 stripe_nr;
> + u64 stripe_len;
> + u64 raid56_full_stripe_start = (u64)-1;
> + int data_stripes;
> +
> + ASSERT(op != BTRFS_MAP_DISCARD);
> +
> + em = btrfs_get_chunk_map(fs_info, logical, len);
> + if (IS_ERR(em))
> + return PTR_ERR(em);
> +
> + map = em->map_lookup;
> + /* Offset of this logical address in the chunk */
> + offset = logical - em->start;
> + /* Len of a stripe in a chunk */
> + stripe_len = map->stripe_len;
> + /* Stripe wher this block falls in */
> + stripe_nr = div64_u64(offset, stripe_len);
> + /* Offset of stripe in the chunk */
> + stripe_offset = stripe_nr * stripe_len;
> + if (offset < stripe_offset) {
> + btrfs_crit(fs_info,
> + "stripe math has gone wrong, stripe_offset=%llu,
> offset=%llu, start=%llu, logical=%llu, stripe_len=%llu",
un-indent long strings
> + stripe_offset, offset, em->start, logical,
> + stripe_len);
> + free_extent_map(em);
> + return -EINVAL;
> + }
> +
> + /* stripe_offset is the offset of this block in its stripe*/
> + stripe_offset = offset - stripe_offset;
> + data_stripes = nr_data_stripes(map);
> +
> +
double newline
> + if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
> + u64 max_len = stripe_len - stripe_offset;
> +
> + /*
> + * In case of raid56, we need to know the stripe aligned start
> + */
> + if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
> + unsigned long full_stripe_len = stripe_len *
> data_stripes;
> + raid56_full_stripe_start = offset;
> +
> + /*
> + * Allow a write of a full stripe, but make sure we
> + * don't allow straddling of stripes
> + */
> + raid56_full_stripe_start =
> div64_u64(raid56_full_stripe_start,
> + full_stripe_len);
> + raid56_full_stripe_start *= full_stripe_len;
> +
> + /*
> + * For writes to RAID[56], allow a full stripeset across
> + * all disks. For other RAID types and for RAID[56]
> + * reads, just allow a single stripe (on a single disk).
> + */
> + if (op == BTRFS_MAP_WRITE) {
> + max_len = stripe_len * data_stripes -
> + (offset - raid56_full_stripe_start);
indentation
> + }
> + }
> + len = min_t(u64, em->len - offset, max_len);
> + } else {
> + len = em->len - offset;
> + }
> +
> + io_geom->len = len;
> + io_geom->offset = offset;
> + io_geom->stripe_len = stripe_len;
> + io_geom->stripe_nr = stripe_nr;
> + io_geom->stripe_offset = stripe_offset;
> + io_geom->raid56_stripe_offset = raid56_full_stripe_start;
> +
> + return 0;
> +}
> +
> static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
> enum btrfs_map_op op,
> u64 logical, u64 *length,
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 7c1ddf35b7d4..f3bdf768bbab 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -421,6 +421,8 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum
> btrfs_map_op op,
> int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
> u64 logical, u64 *length,
> struct btrfs_bio **bbio_ret);
> +int btrfs_io_geometry(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
> + u64 logical, u64 len, struct btrfs_io_geometry *io_geom);
> int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
> u64 physical, u64 **logical, int *naddrs, int *stripe_len);
> int btrfs_read_sys_array(struct btrfs_fs_info *fs_info);
> --
> 2.17.1
