btrfs: sysfs: add btrfs_read_policy_to_enum() helper and refactor read policy store

Introduce btrfs_read_policy_to_enum() helper to simplify the conversion
of a string read policy to its corresponding enum value. This reduces
duplication and improves code clarity in btrfs_read_policy_store().

The parameter is copied locally to allow modification, enabling the
separation of the method and its value. This prepares for the addition of
more functionality in subsequent patches.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 22 insertions, 12 deletions

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index ab18b4e59468..78b4af72997b 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1307,6 +1307,18 @@ BTRFS_ATTR(, temp_fsid, btrfs_temp_fsid_show);
 
 static const char * const btrfs_read_policy_name[] = { "pid" };
 
+static int btrfs_read_policy_to_enum(const char *str)
+{
+	char param[32] = { 0 };
+
+	if (!str || strlen(str) == 0)
+		return 0;
+
+	strncpy(param, str, sizeof(param) - 1);
+
+	return sysfs_match_string(btrfs_read_policy_name, param);
+}
+
 static ssize_t btrfs_read_policy_show(struct kobject *kobj,
 				      struct kobj_attribute *a, char *buf)
 {
@@ -1338,21 +1350,19 @@ static ssize_t btrfs_read_policy_store(struct kobject *kobj,
 				       const char *buf, size_t len)
 {
 	struct btrfs_fs_devices *fs_devices = to_fs_devs(kobj);
-	int i;
+	int index;
 
-	for (i = 0; i < BTRFS_NR_READ_POLICY; i++) {
-		if (sysfs_streq(buf, btrfs_read_policy_name[i])) {
-			if (i != READ_ONCE(fs_devices->read_policy)) {
-				WRITE_ONCE(fs_devices->read_policy, i);
-				btrfs_info(fs_devices->fs_info,
-					   "read policy set to '%s'",
-					   btrfs_read_policy_name[i]);
-			}
-			return len;
-		}
+	index = btrfs_read_policy_to_enum(buf);
+	if (index < 0)
+		return -EINVAL;
+
+	if (index != READ_ONCE(fs_devices->read_policy)) {
+		WRITE_ONCE(fs_devices->read_policy, index);
+		btrfs_info(fs_devices->fs_info, "read policy set to '%s'",
+			   btrfs_read_policy_name[index]);
 	}
 
-	return -EINVAL;
+	return len;
 }
 BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store);