2 files changed, 13 insertions, 1 deletions

diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
index 429f4b263cf1..ca917973c2c0 100644
--- a/fs/jbd/transaction.c
+++ b/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);
diff --git a/include/linux/jbd.h b/include/linux/jbd.h
index 558cb4c26ec9..751bb3849467 100644
--- a/include/linux/jbd.h
+++ b/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