ext4: use correct criteria name instead stale integer number in comment

Use correct criteria name instead stale integer number in comment
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240424061904.987525-5-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -213,11 +213,14 @@ enum criteria {
 #define EXT4_MB_USE_RESERVED		0x2000
 /* Do strict check for free blocks while retrying block allocation */
 #define EXT4_MB_STRICT_CHECK		0x4000
-/* Large fragment size list lookup succeeded at least once for cr = 0 */
+/* Large fragment size list lookup succeeded at least once for
+ * CR_POWER2_ALIGNED */
 #define EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED		0x8000
-/* Avg fragment size rb tree lookup succeeded at least once for cr = 1 */
+/* Avg fragment size rb tree lookup succeeded at least once for
+ * CR_GOAL_LEN_FAST */
 #define EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED		0x00010000
-/* Avg fragment size rb tree lookup succeeded at least once for cr = 1.5 */
+/* Avg fragment size rb tree lookup succeeded at least once for
+ * CR_BEST_AVAIL_LEN */
 #define EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED		0x00020000
 
 struct ext4_allocation_request {

fs/ext4/mballoc.c

@@ -1135,8 +1135,9 @@ static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac,
 		ext4_mb_choose_next_group_best_avail(ac, new_cr, group);
 	} else {
 		/*
-		 * TODO: For CR=2, we can arrange groups in an rb tree sorted by
-		 * bb_free. But until that happens, we should never come here.
+		 * TODO: For CR_GOAL_LEN_SLOW, we can arrange groups in an
+		 * rb tree sorted by bb_free. But until that happens, we should
+		 * never come here.
 		 */
 		WARN_ON(1);
 	}
@@ -2683,7 +2684,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
 		int ret;
 
 		/*
-		 * cr=CR_POWER2_ALIGNED/CR_GOAL_LEN_FAST is a very optimistic
+		 * CR_POWER2_ALIGNED/CR_GOAL_LEN_FAST is a very optimistic
 		 * search to find large good chunks almost for free. If buddy
 		 * data is not ready, then this optimization makes no sense. But
 		 * we never skip the first block group in a flex_bg, since this
@@ -3448,10 +3449,11 @@ static int ext4_mb_init_backend(struct super_block *sb)
 	}
 	if (sbi->s_mb_prefetch > ext4_get_groups_count(sb))
 		sbi->s_mb_prefetch = ext4_get_groups_count(sb);
-	/* now many real IOs to prefetch within a single allocation at cr=0
-	 * given cr=0 is an CPU-related optimization we shouldn't try to
-	 * load too many groups, at some point we should start to use what
-	 * we've got in memory.
+	/*
+	 * now many real IOs to prefetch within a single allocation at
+	 * CR_POWER2_ALIGNED. Given CR_POWER2_ALIGNED is an CPU-related
+	 * optimization we shouldn't try to load too many groups, at some point
+	 * we should start to use what we've got in memory.
 	 * with an average random access time 5ms, it'd take a second to get
 	 * 200 groups (* N with flex_bg), so let's make this limit 4
 	 */

fs/ext4/mballoc.h

@@ -187,8 +187,8 @@ struct ext4_allocation_context {
 	struct ext4_free_extent ac_f_ex;
 
 	/*
-	 * goal len can change in CR1.5, so save the original len. This is
-	 * used while adjusting the PA window and for accounting.
+	 * goal len can change in CR_BEST_AVAIL_LEN, so save the original len.
+	 * This is used while adjusting the PA window and for accounting.
 	 */
 	ext4_grpblk_t	ac_orig_goal_len;