[PATCH v2 2/2] mm: huge_memory: refactor defrag_show() to use defrag_flags[]

[Breno Leitao <leitao@debian.org>]

Replace the hardcoded if/else chain of test_bit() calls and string
literals in defrag_show() with a loop over defrag_flags[] and
defrag_mode_strings[] arrays introduced in the previous commit.

This makes defrag_show() consistent with defrag_store() and eliminates
the duplicated mode name strings.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 mm/huge_memory.c | 38 ++++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 76f2d32428c7f..6993c6d8709dc 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -455,24 +455,30 @@ static const enum transparent_hugepage_flag defrag_flags[] = {
 static ssize_t defrag_show(struct kobject *kobj,
 			   struct kobj_attribute *attr, char *buf)
 {
-	const char *output;
+	int active = DEFRAG_NEVER;
+	int len = 0;
+	int i;
 
-	if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
-		     &transparent_hugepage_flags))
-		output = "[always] defer defer+madvise madvise never";
-	else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
-			  &transparent_hugepage_flags))
-		output = "always [defer] defer+madvise madvise never";
-	else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
-			  &transparent_hugepage_flags))
-		output = "always defer [defer+madvise] madvise never";
-	else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
-			  &transparent_hugepage_flags))
-		output = "always defer defer+madvise [madvise] never";
-	else
-		output = "always defer defer+madvise madvise [never]";
+	for (i = 0; i < ARRAY_SIZE(defrag_flags); i++) {
+		if (test_bit(defrag_flags[i], &transparent_hugepage_flags)) {
+			active = i;
+			break;
+		}
+	}
 
-	return sysfs_emit(buf, "%s\n", output);
+	for (i = 0; i < ARRAY_SIZE(defrag_mode_strings); i++) {
+		if (i == active)
+			len += sysfs_emit_at(buf, len, "[%s] ",
+					     defrag_mode_strings[i]);
+		else
+			len += sysfs_emit_at(buf, len, "%s ",
+					     defrag_mode_strings[i]);
+	}
+
+	/* Replace trailing space with newline */
+	buf[len - 1] = '\n';
+
+	return len;
 }
 
 static ssize_t defrag_store(struct kobject *kobj,

-- 
2.52.0