---

yaml
---
r: 19805
b: refs/heads/master
c: fe1dcbc
h: refs/heads/master
i:
  19803: e08f858
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: bc5e483da61eb5ab8d24b4a919fb512e5886d02c
+refs/heads/master: fe1dcbc4f311c2e6c23b33c0fa8572461618ab3e

trunk/fs/jbd/transaction.c

@@ -1308,6 +1308,7 @@ int journal_stop(handle_t *handle)
 	transaction_t *transaction = handle->h_transaction;
 	journal_t *journal = transaction->t_journal;
 	int old_handle_count, err;
+	pid_t pid;
 
 	J_ASSERT(transaction->t_updates > 0);
 	J_ASSERT(journal_current_handle() == handle);
@@ -1333,8 +1334,15 @@ int journal_stop(handle_t *handle)
 	 * It doesn't cost much - we're about to run a commit and sleep
 	 * on IO anyway.  Speeds up many-threaded, many-dir operations
 	 * by 30x or more...
+	 *
+	 * But don't do this if this process was the most recent one 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.
 	 */
-	if (handle->h_sync) {
+	pid = current->pid;
+	if (handle->h_sync && journal->j_last_sync_writer != pid) {
+		journal->j_last_sync_writer = pid;
 		do {
 			old_handle_count = transaction->t_handle_count;
 			schedule_timeout_uninterruptible(1);

trunk/include/linux/jbd.h

@@ -23,6 +23,7 @@
 #define jfs_debug jbd_debug
 #else
 
+#include <linux/types.h>
 #include <linux/buffer_head.h>
 #include <linux/journal-head.h>
 #include <linux/stddef.h>
@@ -618,6 +619,7 @@ struct transaction_s
  * @j_wbuf: array of buffer_heads for journal_commit_transaction
  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
  *	number that will fit in j_blocksize
+ * @j_last_sync_writer: most recent pid which did a synchronous write
  * @j_private: An opaque pointer to fs-private information.
  */
 
@@ -807,6 +809,8 @@ struct journal_s
 	struct buffer_head	**j_wbuf;
 	int			j_wbufsize;
 
+	pid_t			j_last_sync_writer;
+
 	/*
 	 * An opaque pointer to fs-private information.  ext3 puts its
 	 * superblock pointer here