[PATCH 6/6] btrfs: Remove dead code exclude_super_stripes

[Nikolay Borisov <nborisov@suse.com>]

Adresses held in 'logical' array are always guaranteed to fall within
the boundaries of the block group. That is, 'start' can never be
smaller than cache->start. This invariant follows from the way the
address are calculated in btrfs_rmap_block:

    stripe_nr = physical - map->stripes[i].physical;
    stripe_nr = div64_u64(stripe_nr, map->stripe_len);
    bytenr = chunk_start + stripe_nr * io_stripe_size;

I.e it's always some IO stripe within the given chunk.

Exploit this invariant to simplify the body of the loop by removing the
unnecessary 'if' since its 'else' part is the one always executed.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/block-group.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 2ab4d9cb598a..3c7c34b6a0a8 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1627,25 +1627,12 @@ static int exclude_super_stripes(struct btrfs_block_group *cache)
 			return ret;
 
 		while (nr--) {
-			u64 start, len;
-
-			if (logical[nr] > cache->start + cache->length)
-				continue;
-
-			if (logical[nr] + stripe_len <= cache->start)
-				continue;
-
-			start = logical[nr];
-			if (start < cache->start) {
-				start = cache->start;
-				len = (logical[nr] + stripe_len) - start;
-			} else {
-				len = min_t(u64, stripe_len,
-					    cache->start + cache->length - start);
-			}
+			u64 len = min_t(u64, stripe_len,
+				cache->start + cache->length - logical[nr]);
 
 			cache->bytes_super += len;
-			ret = btrfs_add_excluded_extent(fs_info, start, len);
+			ret = btrfs_add_excluded_extent(fs_info, logical[nr],
+							len);
 			if (ret) {
 				kfree(logical);
 				return ret;
-- 
2.17.1