ext4: factor out __ext4_mb_scan_group()

Extract __ext4_mb_scan_group() to make the code clearer and to
prepare for the later conversion of 'choose group' to 'scan groups'.
No functional changes.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-13-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

2 files changed, 29 insertions, 18 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index fada0d1b3fdb..650eb6366eb0 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2568,6 +2568,30 @@ void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
 	}
 }
 
+static void __ext4_mb_scan_group(struct ext4_allocation_context *ac)
+{
+	bool is_stripe_aligned;
+	struct ext4_sb_info *sbi;
+	enum criteria cr = ac->ac_criteria;
+
+	ac->ac_groups_scanned++;
+	if (cr == CR_POWER2_ALIGNED)
+		return ext4_mb_simple_scan_group(ac, ac->ac_e4b);
+
+	sbi = EXT4_SB(ac->ac_sb);
+	is_stripe_aligned = false;
+	if ((sbi->s_stripe >= sbi->s_cluster_ratio) &&
+	    !(ac->ac_g_ex.fe_len % EXT4_NUM_B2C(sbi, sbi->s_stripe)))
+		is_stripe_aligned = true;
+
+	if ((cr == CR_GOAL_LEN_FAST || cr == CR_BEST_AVAIL_LEN) &&
+	    is_stripe_aligned)
+		ext4_mb_scan_aligned(ac, ac->ac_e4b);
+
+	if (ac->ac_status == AC_STATUS_CONTINUE)
+		ext4_mb_complex_scan_group(ac, ac->ac_e4b);
+}
+
 /*
  * This is also called BEFORE we load the buddy bitmap.
  * Returns either 1 or 0 indicating that the group is either suitable
@@ -2855,6 +2879,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
 	 */
 	if (ac->ac_2order)
 		cr = CR_POWER2_ALIGNED;
+
+	ac->ac_e4b = &e4b;
 repeat:
 	for (; cr < EXT4_MB_NUM_CRS && ac->ac_status == AC_STATUS_CONTINUE; cr++) {
 		ac->ac_criteria = cr;
@@ -2932,24 +2958,7 @@ repeat:
 				continue;
 			}
 
-			ac->ac_groups_scanned++;
-			if (cr == CR_POWER2_ALIGNED)
-				ext4_mb_simple_scan_group(ac, &e4b);
-			else {
-				bool is_stripe_aligned =
-					(sbi->s_stripe >=
-					 sbi->s_cluster_ratio) &&
-					!(ac->ac_g_ex.fe_len %
-					  EXT4_NUM_B2C(sbi, sbi->s_stripe));
-
-				if ((cr == CR_GOAL_LEN_FAST ||
-				     cr == CR_BEST_AVAIL_LEN) &&
-				    is_stripe_aligned)
-					ext4_mb_scan_aligned(ac, &e4b);
-
-				if (ac->ac_status == AC_STATUS_CONTINUE)
-					ext4_mb_complex_scan_group(ac, &e4b);
-			}
+			__ext4_mb_scan_group(ac);
 
 			ext4_unlock_group(sb, group);
 			ext4_mb_unload_buddy(&e4b);
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index f8280de3e882..7a60b0103e64 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -204,6 +204,8 @@ struct ext4_allocation_context {
 	__u8 ac_2order;		/* if request is to allocate 2^N blocks and
 				 * N > 0, the field stores N, otherwise 0 */
 	__u8 ac_op;		/* operation, for history only */
+
+	struct ext4_buddy *ac_e4b;
 	struct folio *ac_bitmap_folio;
 	struct folio *ac_buddy_folio;
 	struct ext4_prealloc_space *ac_pa;