From: Jeff Mahoney <je...@suse.com>

Overloading extent_map->bdev to struct map_lookup * might have started out
as a means to an end, but it's a pattern that's used all over the place
now. Let's get rid of the casting and just add a union instead.

Signed-off-by: Jeff Mahoney <je...@suse.com>
---
 fs/btrfs/dev-replace.c |  2 +-
 fs/btrfs/extent_map.c  |  2 +-
 fs/btrfs/extent_map.h  | 10 +++++++++-
 fs/btrfs/scrub.c       |  2 +-
 fs/btrfs/volumes.c     | 24 ++++++++++++------------
 5 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 0573848..2ad3289 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -613,7 +613,7 @@ static void btrfs_dev_replace_update_device_in_mapping_tree(
                em = lookup_extent_mapping(em_tree, start, (u64)-1);
                if (!em)
                        break;
-               map = (struct map_lookup *)em->bdev;
+               map = em->map_lookup;
                for (i = 0; i < map->num_stripes; i++)
                        if (srcdev == map->stripes[i].dev)
                                map->stripes[i].dev = tgtdev;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 6a98bdd..84fb56d 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -76,7 +76,7 @@ void free_extent_map(struct extent_map *em)
                WARN_ON(extent_map_in_tree(em));
                WARN_ON(!list_empty(&em->list));
                if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
-                       kfree(em->bdev);
+                       kfree(em->map_lookup);
                kmem_cache_free(extent_map_cache, em);
        }
 }
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index b2991fd..eb8b8fa 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -32,7 +32,15 @@ struct extent_map {
        u64 block_len;
        u64 generation;
        unsigned long flags;
-       struct block_device *bdev;
+       union {
+               struct block_device *bdev;
+
+               /*
+                * used for chunk mappings
+                * flags & EXTENT_FLAG_FS_MAPPING must be set
+                */
+               struct map_lookup *map_lookup;
+       };
        atomic_t refs;
        unsigned int compress_type;
        struct list_head list;
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index ab58115..19f7241d 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3339,7 +3339,7 @@ static noinline_for_stack int scrub_chunk(struct 
scrub_ctx *sctx,
        if (!em)
                return -EINVAL;
 
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        if (em->start != chunk_offset)
                goto out;
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7fdde31..9f48ae5 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1068,7 +1068,7 @@ again:
                struct map_lookup *map;
                int i;
 
-               map = (struct map_lookup *)em->bdev;
+               map = em->map_lookup;
                for (i = 0; i < map->num_stripes; i++) {
                        if (map->stripes[i].dev != device)
                                continue;
@@ -2622,7 +2622,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans,
                        free_extent_map(em);
                return -EINVAL;
        }
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
 
        for (i = 0; i < map->num_stripes; i++) {
                struct btrfs_device *device = map->stripes[i].dev;
@@ -4465,7 +4465,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle 
*trans,
                goto error;
        }
        set_bit(EXTENT_FLAG_FS_MAPPING, &em->flags);
-       em->bdev = (struct block_device *)map;
+       em->map_lookup = map;
        em->start = start;
        em->len = num_bytes;
        em->block_start = 0;
@@ -4560,7 +4560,7 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle 
*trans,
                return -EINVAL;
        }
 
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        item_size = btrfs_chunk_item_size(map->num_stripes);
        stripe_size = em->orig_block_len;
 
@@ -4702,7 +4702,7 @@ int btrfs_chunk_readonly(struct btrfs_root *root, u64 
chunk_offset)
        if (!em)
                return 1;
 
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        for (i = 0; i < map->num_stripes; i++) {
                if (map->stripes[i].dev->missing) {
                        miss_ndevs++;
@@ -4782,7 +4782,7 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 
logical, u64 len)
                return 1;
        }
 
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
                ret = map->num_stripes;
        else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
@@ -4818,7 +4818,7 @@ unsigned long btrfs_full_stripe_len(struct btrfs_root 
*root,
        BUG_ON(!em);
 
        BUG_ON(em->start > logical || em->start + em->len < logical);
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
                len = map->stripe_len * nr_data_stripes(map);
        free_extent_map(em);
@@ -4839,7 +4839,7 @@ int btrfs_is_parity_mirror(struct btrfs_mapping_tree 
*map_tree,
        BUG_ON(!em);
 
        BUG_ON(em->start > logical || em->start + em->len < logical);
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
                ret = 1;
        free_extent_map(em);
@@ -5000,7 +5000,7 @@ static int __btrfs_map_block(struct btrfs_fs_info 
*fs_info, int rw,
                return -EINVAL;
        }
 
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
        offset = logical - em->start;
 
        stripe_len = map->stripe_len;
@@ -5542,7 +5542,7 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
                free_extent_map(em);
                return -EIO;
        }
-       map = (struct map_lookup *)em->bdev;
+       map = em->map_lookup;
 
        length = em->len;
        rmap_len = map->stripe_len;
@@ -6057,7 +6057,7 @@ static int read_one_chunk(struct btrfs_root *root, struct 
btrfs_key *key,
        }
 
        set_bit(EXTENT_FLAG_FS_MAPPING, &em->flags);
-       em->bdev = (struct block_device *)map;
+       em->map_lookup = map;
        em->start = logical;
        em->len = length;
        em->orig_start = 0;
@@ -6733,7 +6733,7 @@ void btrfs_update_commit_device_bytes_used(struct 
btrfs_root *root,
        /* In order to kick the device replace finish process */
        lock_chunks(root);
        list_for_each_entry(em, &transaction->pending_chunks, list) {
-               map = (struct map_lookup *)em->bdev;
+               map = em->map_lookup;
 
                for (i = 0; i < map->num_stripes; i++) {
                        dev = map->stripes[i].dev;
-- 
1.8.4.5

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