[PATCH] ext4: disable synchronous transaction batching if max_batch_time==0
From: Eric Sandeen <hidden>
Date: 2014-06-10 00:10:46
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), journalling layer for block devices (jbd2), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Jan Kara, Linus Torvalds
The mount manpage says of the max_batch_time option, This optimization can be turned off entirely by setting max_batch_time to 0. But the code doesn't do that. So fix the code to do that. Signed-off-by: Eric Sandeen <redacted> --- Lightly tested: it mounts, accepts the mount option == 0, shows "0" in /proc/mounts, and does basic IO & unmounts without crashing. ;)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6f9e6fa..ab5a791 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c@@ -1524,8 +1524,6 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token, arg = JBD2_DEFAULT_MAX_COMMIT_AGE; sbi->s_commit_interval = HZ * arg; } else if (token == Opt_max_batch_time) { - if (arg == 0) - arg = EXT4_DEF_MAX_BATCH_TIME; sbi->s_max_batch_time = arg; } else if (token == Opt_min_batch_time) { sbi->s_min_batch_time = arg;
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 38cfcf5..6f0f590 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c@@ -1588,9 +1588,12 @@ int jbd2_journal_stop(handle_t *handle) * to perform a synchronous write. We do this to detect the * case where a single process is doing a stream of sync * writes. No point in waiting for joiners in that case. + * + * Setting max_batch_time to 0 disables this completely. */ pid = current->pid; - if (handle->h_sync && journal->j_last_sync_writer != pid) { + if (handle->h_sync && journal->j_last_sync_writer != pid && + journal->j_max_batch_time) { u64 commit_time, trans_time; journal->j_last_sync_writer = pid;