From 96f9b0f2fa01c96e90abd4e981208a341a5da66e Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <nborisov@suse.com>
Date: Fri, 3 Apr 2020 16:40:35 +0300
Subject: [PATCH] btrfs: simplify checks when adding excluded ranges
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>
Signed-off-by: David Sterba <dsterba@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 956ae6283d332..e29e9629b246b 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1741,25 +1741,12 @@ 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;
--
2.30.2