ext4: add fsync batch tuning knobs
Add new mount options, min_batch_time and max_batch_time, which
controls how long the jbd2 layer should wait for additional filesystem
operations to get batched with a synchronous write transaction.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ac8551e..9ba9fd6 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -328,6 +328,7 @@
uid_t s_resuid;
gid_t s_resgid;
unsigned long s_commit_interval;
+ u32 s_min_batch_time, s_max_batch_time;
#ifdef CONFIG_QUOTA
int s_jquota_fmt;
char *s_qf_names[MAXQUOTAS];
@@ -806,6 +807,12 @@
#define EXT4_DEFM_JMODE_WBACK 0x0060
/*
+ * Default journal batch times
+ */
+#define EXT4_DEF_MIN_BATCH_TIME 0
+#define EXT4_DEF_MAX_BATCH_TIME 15000 /* 15ms */
+
+/*
* Structure of a directory entry
*/
#define EXT4_NAME_LEN 255