[PATCH 08/13] btrfs: factor out block mapping for RAID5/6

Johannes Thumshirn
2023-12-12T12:39:01Z

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of RAID5 and RAID6, factor out a helper
calculating this information.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/btrfs/volumes.c | 91 +++++++++++++++++++++++++++++-------------------------
1 file changed, 49 insertions(+), 42 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bc0988d8bd56..fd213bb7d619 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6437,6 +6437,54 @@ static void map_blocks_for_raid10(struct btrfs_fs_info *fs_info,
io_geom->mirror_num = io_geom->stripe_index - old_stripe_index + 1;
}

+static void map_blocks_for_raid56(struct btrfs_chunk_map *map,
+ enum btrfs_map_op op,
+ struct btrfs_io_geometry *io_geom,
+ u64 logical, u64 *length)
+{
+ int data_stripes = nr_data_stripes(map);
+
+ if (op != BTRFS_MAP_READ || io_geom->mirror_num > 1) {
+ /*
+ * Needs full stripe mapping.
+ *
+ * Push stripe_nr back to the start of the full stripe
+ * For those cases needing a full stripe, @stripe_nr
+ * is the full stripe number.
+ *
+ * Originally we go raid56_full_stripe_start / full_stripe_len,
+ * but that can be expensive. Here we just divide
+ * @stripe_nr with @data_stripes.
+ */
+ io_geom->stripe_nr /= data_stripes;
+
+ /* RAID[56] write or recovery. Return all stripes */
+ io_geom->num_stripes = map->num_stripes;
+ io_geom->max_errors = btrfs_chunk_max_errors(map);
+
+ /* Return the length to the full stripe end */
+ *length = min(logical + *length,
+ io_geom->raid56_full_stripe_start + map->start +
+ btrfs_stripe_nr_to_offset(data_stripes)) -
+ logical;
+ io_geom->stripe_index = 0;
+ io_geom->stripe_offset = 0;
+ return;
+ }
+
+ ASSERT(io_geom->mirror_num <= 1);
+ /* Just grab the data stripe directly. */
+ io_geom->stripe_index = io_geom->stripe_nr % data_stripes;
+ io_geom->stripe_nr /= data_stripes;
+
+ /* We distribute the parity blocks across stripes */
+ io_geom->stripe_index =
+ (io_geom->stripe_nr + io_geom->stripe_index) % map->num_stripes;
+
+ if (op == BTRFS_MAP_READ && io_geom->mirror_num < 1)
+ io_geom->mirror_num = 1;
+}
+
/*
* Map one logical range to one or more physical ranges.
*
@@ -6529,48 +6577,7 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
map_blocks_for_raid10(fs_info, map, op, &io_geom,
dev_replace_is_ongoing);
} else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
- int data_stripes = nr_data_stripes(map);
-
- if (op != BTRFS_MAP_READ || io_geom.mirror_num > 1) {
- /*
- * Needs full stripe mapping.
- *
- * Push stripe_nr back to the start of the full stripe
- * For those cases needing a full stripe, @stripe_nr
- * is the full stripe number.
- *
- * Originally we go raid56_full_stripe_start / full_stripe_len,
- * but that can be expensive. Here we just divide
- * @stripe_nr with @data_stripes.
- */
- io_geom.stripe_nr /= data_stripes;
-
- /* RAID[56] write or recovery. Return all stripes */
- io_geom.num_stripes = map->num_stripes;
- io_geom.max_errors = btrfs_chunk_max_errors(map);
-
- /* Return the length to the full stripe end */
- *length = min(logical + *length,
- io_geom.raid56_full_stripe_start +
- map->start +
- btrfs_stripe_nr_to_offset(
- data_stripes)) -
- logical;
- io_geom.stripe_index = 0;
- io_geom.stripe_offset = 0;
- } else {
- ASSERT(io_geom.mirror_num <= 1);
- /* Just grab the data stripe directly. */
- io_geom.stripe_index = io_geom.stripe_nr % data_stripes;
- io_geom.stripe_nr /= data_stripes;
-
- /* We distribute the parity blocks across stripes */
- io_geom.stripe_index =
- (io_geom.stripe_nr + io_geom.stripe_index) %
- map->num_stripes;
- if (op == BTRFS_MAP_READ && io_geom.mirror_num < 1)
- io_geom.mirror_num = 1;
- }
+ map_blocks_for_raid56(map, op, &io_geom, logical, length);
} else {
/*
* After this, stripe_nr is the number of stripes on this

--
2.43.0