linux-kernel - [PATCH v2] btrfs: Remove redundant initialization of 'to

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Date:   Mon, 17 May 2021 17:46:50 +0800
From:   Yang Li <yang.lee@...ux.alibaba.com>
To:     clm@...com
Cc:     josef@...icpanda.com, dsterba@...e.com, nathan@...nel.org,
        ndesaulniers@...gle.com, linux-btrfs@...r.kernel.org,
        lukas.bulwahn@...il.com, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Yang Li <yang.lee@...ux.alibaba.com>
Subject: [PATCH v2] btrfs: Remove redundant initialization of 'to_add'

Variable 'to_add' is being initialized however this value is never
read as 'to_add' is assigned a new value in if statement. Remove the
redundant assignment. At the same time, move its declaration into the
if statement, because the variable is not used elsewhere.

Clean up clang warning:

fs/btrfs/extent-tree.c:2774:8: warning: Value stored to 'to_add' during
its initialization is never read [clang-analyzer-deadcode.DeadStores]

Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>
---

Change in v2:
--According to Lukas's suggestion, combine the declaration and assignment of 
  variable 'to_add' into one line, just as "u64 to_add = min(len, ...);"
  https://lore.kernel.org/patchwork/patch/1428697/

 fs/btrfs/extent-tree.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f1d15b6..13ac978 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2774,11 +2774,9 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 		spin_unlock(&cache->lock);
 		if (!readonly && return_free_space &&
 		    global_rsv->space_info == space_info) {
-			u64 to_add = len;
-
 			spin_lock(&global_rsv->lock);
 			if (!global_rsv->full) {
-				to_add = min(len, global_rsv->size -
+				u64 to_add = min(len, global_rsv->size -
 					     global_rsv->reserved);
 				global_rsv->reserved += to_add;
 				btrfs_space_info_update_bytes_may_use(fs_info,
-- 
1.8.3.1