jbd2: optimize jbd2_journal_force_commit

Current implementation of jbd2_journal_force_commit() is suboptimal because
result in empty and useless commits. But callers just want to force and wait
any unfinished commits. We already have jbd2_journal_force_commit_nested()
which does exactly what we want, except we are guaranteed that we do not hold
journal transaction open.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 70990d682a0cf25a9e24df94e1a3289c097dbdee..0e6c13bdcc149f98aad310e5b0c67a500e428f08 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -529,20 +529,17 @@ int jbd2_log_start_commit(journal_t *journal, tid_t tid)
 }
 
 /*
- * Force and wait upon a commit if the calling process is not within
- * transaction.  This is used for forcing out undo-protected data which contains
- * bitmaps, when the fs is running out of space.
- *
- * We can only force the running transaction if we don't have an active handle;
- * otherwise, we will deadlock.
- *
- * Returns true if a transaction was started.
+ * Force and wait any uncommitted transactions.  We can only force the running
+ * transaction if we don't have an active handle, otherwise, we will deadlock.
+ * Returns: <0 in case of error,
+ *           0 if nothing to commit,
+ *           1 if transaction was successfully committed.
  */
-int jbd2_journal_force_commit_nested(journal_t *journal)
+static int __jbd2_journal_force_commit(journal_t *journal)
 {
        transaction_t *transaction = NULL;
        tid_t tid;
-       int need_to_start = 0;
+       int need_to_start = 0, ret = 0;
 
        read_lock(&journal->j_state_lock);
        if (journal->j_running_transaction && !current->journal_info) {
@@ -553,16 +550,53 @@ int jbd2_journal_force_commit_nested(journal_t *journal)
                transaction = journal->j_committing_transaction;
 
        if (!transaction) {
+               /* Nothing to commit */
                read_unlock(&journal->j_state_lock);
-               return 0;       /* Nothing to retry */
+               return 0;
        }
-
        tid = transaction->t_tid;
        read_unlock(&journal->j_state_lock);
        if (need_to_start)
                jbd2_log_start_commit(journal, tid);
-       jbd2_log_wait_commit(journal, tid);
-       return 1;
+       ret = jbd2_log_wait_commit(journal, tid);
+       if (!ret)
+               ret = 1;
+
+       return ret;
+}
+
+/**
+ * Force and wait upon a commit if the calling process is not within
+ * transaction.  This is used for forcing out undo-protected data which contains
+ * bitmaps, when the fs is running out of space.
+ *
+ * @journal: journal to force
+ * Returns true if progress was made.
+ */
+int jbd2_journal_force_commit_nested(journal_t *journal)
+{
+       int ret;
+
+       ret = __jbd2_journal_force_commit(journal);
+       return ret > 0;
+}
+
+/**
+ * int journal_force_commit() - force any uncommitted transactions
+ * @journal: journal to force
+ *
+ * Caller want unconditional commit. We can only force the running transaction
+ * if we don't have an active handle, otherwise, we will deadlock.
+ */
+int jbd2_journal_force_commit(journal_t *journal)
+{
+       int ret;
+
+       J_ASSERT(!current->journal_info);
+       ret = __jbd2_journal_force_commit(journal);
+       if (ret > 0)
+               ret = 0;
+       return ret;
 }
 
 /*

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index f33342a2a95ef65651b988b91e7d6f0e5db66e02..dd422e6804183a5539f0174ce5ac004c2cb05956 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1661,29 +1661,6 @@ int jbd2_journal_stop(handle_t *handle)
        return err;
 }
 
-/**
- * int jbd2_journal_force_commit() - force any uncommitted transactions
- * @journal: journal to force
- *
- * For synchronous operations: force any uncommitted transactions
- * to disk.  May seem kludgy, but it reuses all the handle batching
- * code in a very simple manner.
- */
-int jbd2_journal_force_commit(journal_t *journal)
-{
-       handle_t *handle;
-       int ret;
-
-       handle = jbd2_journal_start(journal, 1);
-       if (IS_ERR(handle)) {
-               ret = PTR_ERR(handle);
-       } else {
-               handle->h_sync = 1;
-               ret = jbd2_journal_stop(handle);
-       }
-       return ret;
-}
-
 /*
  *
  * List management code snippets: various functions for manipulating the

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index fb91c8debe6a72a067c4172ff1bacb407e8080a3..c3645b9475f1029e2f89dc22aa541681957172fa 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1160,6 +1160,7 @@ extern void          jbd2_journal_ack_err    (journal_t *);
 extern int        jbd2_journal_clear_err  (journal_t *);
 extern int        jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
 extern int        jbd2_journal_force_commit(journal_t *);
+extern int        jbd2_journal_force_commit_nested(journal_t *);
 extern int        jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
 extern int        jbd2_journal_begin_ordered_truncate(journal_t *journal,
                                struct jbd2_inode *inode, loff_t new_size);
@@ -1235,7 +1236,6 @@ extern void       jbd2_clear_buffer_revoked_flags(journal_t *journal);
 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
-int jbd2_journal_force_commit_nested(journal_t *journal);
 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
 int jbd2_complete_transaction(journal_t *journal, tid_t tid);
 int jbd2_log_do_checkpoint(journal_t *journal);