[PATCH v2] ext4: Enable code path when DX_DEBUG is set

[Vinicius Tinti]

By enabling -Wunreachable-code-aggressive on Clang the following code
paths are unreachable.

This has been present since commit ac27a0ec112a ("[PATCH] ext4: initial
copy of files from ext3") and fs/ext3 had it present at the beginning of
git history. It has not been changed since.

Clang warns:

fs/ext4/namei.c:831:17: warning: code will never be executed
[-Wunreachable-code]
                        unsigned n = count - 1;
                                     ^~~~~
fs/ext4/namei.c:830:7: note: silence by adding parentheses to mark code as
explicitly dead
                if (0) { // linear search cross check
                    ^
                    /* DISABLES CODE */ ( )

Signed-off-by: Vinicius Tinti <viniciusti...@gmail.com>
---
 fs/ext4/namei.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index cf652ba3e74d..46ae6a4e4be5 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -827,20 +827,21 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
                                p = m + 1;
                }
 
-               if (0) { // linear search cross check
-                       unsigned n = count - 1;
-                       at = entries;
-                       while (n--)
+#ifdef DX_DEBUG
+               // linear search cross check
+               unsigned n = count - 1;
+               at = entries;
+               while (n--)
+               {
+                       dxtrace(printk(KERN_CONT ","));
+                       if (dx_get_hash(++at) > hash)
                        {
-                               dxtrace(printk(KERN_CONT ","));
-                               if (dx_get_hash(++at) > hash)
-                               {
-                                       at--;
-                                       break;
-                               }
+                               at--;
+                               break;
                        }
-                       ASSERT(at == p - 1);
                }
+               ASSERT(at == p - 1);
+#endif
 
                at = p - 1;
                dxtrace(printk(KERN_CONT " %x->%u\n",
-- 
2.25.1