ext4: Convert mballoc cr (criteria) to enum

Convert criteria to be an enum so it easier to maintain and
update the tracefiles to use enum names. This change also makes
it easier to insert new criterias in the future.

There is no functional change in this patch.
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/5d82fd467bdf70ea45bdaef810af3b146013946c.1685449706.git.ojaswin@linux.ibm.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -127,6 +127,23 @@ enum SHIFT_DIRECTION {
 	SHIFT_RIGHT,
 };
 
+/*
+ * Number of criterias defined. For each criteria, mballoc has slightly
+ * different way of finding the required blocks nad usually, higher the
+ * criteria the slower the allocation. We start at lower criterias and keep
+ * falling back to higher ones if we are not able to find any blocks.
+ */
+#define EXT4_MB_NUM_CRS 4
+/*
+ * All possible allocation criterias for mballoc
+ */
+enum criteria {
+	CR0,
+	CR1,
+	CR2,
+	CR3,
+};
+
 /*
  * Flags used in mballoc's allocation_context flags field.
  *
@@ -1544,9 +1561,9 @@ struct ext4_sb_info {
 	atomic_t s_bal_2orders;	/* 2^order hits */
 	atomic_t s_bal_cr0_bad_suggestions;
 	atomic_t s_bal_cr1_bad_suggestions;
-	atomic64_t s_bal_cX_groups_considered[4];
-	atomic64_t s_bal_cX_hits[4];
-	atomic64_t s_bal_cX_failed[4];		/* cX loop didn't find blocks */
+	atomic64_t s_bal_cX_groups_considered[EXT4_MB_NUM_CRS];
+	atomic64_t s_bal_cX_hits[EXT4_MB_NUM_CRS];
+	atomic64_t s_bal_cX_failed[EXT4_MB_NUM_CRS];		/* cX loop didn't find blocks */
 	atomic_t s_mb_buddies_generated;	/* number of buddies generated */
 	atomic64_t s_mb_generation_time;
 	atomic_t s_mb_lost_chunks;

include/trace/events/ext4.h

@@ -120,6 +120,18 @@ TRACE_DEFINE_ENUM(EXT4_FC_REASON_MAX);
 		{ EXT4_FC_REASON_INODE_JOURNAL_DATA,	"INODE_JOURNAL_DATA"}, \
 		{ EXT4_FC_REASON_ENCRYPTED_FILENAME,	"ENCRYPTED_FILENAME"})
 
+TRACE_DEFINE_ENUM(CR0);
+TRACE_DEFINE_ENUM(CR1);
+TRACE_DEFINE_ENUM(CR2);
+TRACE_DEFINE_ENUM(CR3);
+
+#define show_criteria(cr)                       \
+	__print_symbolic(cr,                    \
+			 { CR0, "CR0" },	\
+			 { CR1, "CR1" },        \
+			 { CR2, "CR2" },        \
+			 { CR3, "CR3" })
+
 TRACE_EVENT(ext4_other_inode_update_time,
 	TP_PROTO(struct inode *inode, ino_t orig_ino),
 
@@ -1063,7 +1075,7 @@ TRACE_EVENT(ext4_mballoc_alloc,
 	),
 
 	TP_printk("dev %d,%d inode %lu orig %u/%d/%u@%u goal %u/%d/%u@%u "
-		  "result %u/%d/%u@%u blks %u grps %u cr %u flags %s "
+		  "result %u/%d/%u@%u blks %u grps %u cr %s flags %s "
 		  "tail %u broken %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  (unsigned long) __entry->ino,
@@ -1073,7 +1085,7 @@ TRACE_EVENT(ext4_mballoc_alloc,
 		  __entry->goal_len, __entry->goal_logical,
 		  __entry->result_group, __entry->result_start,
 		  __entry->result_len, __entry->result_logical,
-		  __entry->found, __entry->groups, __entry->cr,
+		  __entry->found, __entry->groups, show_criteria(__entry->cr),
 		  show_mballoc_flags(__entry->flags), __entry->tail,
 		  __entry->buddy ? 1 << __entry->buddy : 0)
 );