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Date: Tue, 17 May 2011 12:28:14 +0200
From: Jan Kara <jack@...e.cz>
To: tytso@....edu
Cc: Edward Goggin <egoggin@...are.com>, linux-ext4@...r.kernel.org,
Jan Kara <jack@...e.cz>
Subject: [PATCH 1/2] jbd2: Provide function to check whether transaction will issue data barrier
Provide a function which returns whether a transaction with given tid
will send a barrier to the filesystem device. The function will be used
by ext4 to detect whether fsync needs to send a separate barrier or not.
Signed-off-by: Jan Kara <jack@...e.cz>
---
fs/jbd2/commit.c | 6 +++++-
fs/jbd2/journal.c | 37 +++++++++++++++++++++++++++++++++++++
include/linux/jbd2.h | 3 ++-
3 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 6e28000..e7812ed 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -800,6 +800,10 @@ wait_for_iobuf:
jbd2_journal_abort(journal, err);
jbd_debug(3, "JBD: commit phase 5\n");
+ write_lock(&journal->j_state_lock);
+ J_ASSERT(commit_transaction->t_state == T_COMMIT);
+ commit_transaction->t_state = T_COMMIT_RECORD;
+ write_unlock(&journal->j_state_lock);
if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
@@ -955,7 +959,7 @@ restart_loop:
jbd_debug(3, "JBD: commit phase 7\n");
- J_ASSERT(commit_transaction->t_state == T_COMMIT);
+ J_ASSERT(commit_transaction->t_state == T_COMMIT_RECORD);
commit_transaction->t_start = jiffies;
stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index e0ec3db..dbafbc5 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -577,6 +577,43 @@ int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
}
/*
+ * Return 1 if a given transaction has not yet sent barrier request
+ * connected with a transaction commit. If 0 is returned, transaction
+ * may or may not have sent the barrier. Used to avoid sending barrier
+ * twice in common cases.
+ */
+int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
+{
+ int ret = 0;
+ transaction_t *commit_trans;
+
+ /*
+ * For external journal sending data barrier is more complex so just
+ * admit we don't know...
+ */
+ if (!(journal->j_flags & JBD2_BARRIER) ||
+ journal->j_fs_dev != journal->j_dev)
+ return 0;
+ read_lock(&journal->j_state_lock);
+ /* Transaction already committed? */
+ if (tid_geq(journal->j_commit_sequence, tid))
+ goto out;
+ /*
+ * Transaction is being committed and we already proceeded to
+ * submitting barrier?
+ */
+ commit_trans = journal->j_committing_transaction;
+ if (commit_trans && commit_trans->t_tid == tid &&
+ commit_trans->t_state >= T_COMMIT_RECORD)
+ goto out;
+ ret = 1;
+out:
+ read_unlock(&journal->j_state_lock);
+ return ret;
+}
+EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
+
+/*
* Wait for a specified commit to complete.
* The caller may not hold the journal lock.
*/
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index a32dcae..fea6d6f 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -529,9 +529,9 @@ struct transaction_s
enum {
T_RUNNING,
T_LOCKED,
- T_RUNDOWN,
T_FLUSH,
T_COMMIT,
+ T_COMMIT_RECORD,
T_FINISHED
} t_state;
@@ -1228,6 +1228,7 @@ 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_log_do_checkpoint(journal_t *journal);
+int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
void __jbd2_log_wait_for_space(journal_t *journal);
extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
--
1.7.1
--
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