From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 9 Mar 2014 05:46:23 +0000 (-0500)
Subject: jbd2: minimize region locked by j_list_lock in journal_get_create_access()
X-Git-Tag: firefly_0821_release~176^2~4145^2~19
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6e4862a5bb9d12be87e4ea5d9a60836ebed71d28;p=firefly-linux-kernel-4.4.55.git

jbd2: minimize region locked by j_list_lock in journal_get_create_access()

It's not needed until we start trying to modifying fields in the
journal_head which are protected by j_list_lock.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 78900a1252b2..357f3dc5201f 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1073,7 +1073,6 @@ int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
 	 * reused here.
 	 */
 	jbd_lock_bh_state(bh);
-	spin_lock(&journal->j_list_lock);
 	J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
 		jh->b_transaction == NULL ||
 		(jh->b_transaction == journal->j_committing_transaction &&
@@ -1096,12 +1095,14 @@ int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
 		jh->b_modified = 0;
 
 		JBUFFER_TRACE(jh, "file as BJ_Reserved");
+		spin_lock(&journal->j_list_lock);
 		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
 	} else if (jh->b_transaction == journal->j_committing_transaction) {
 		/* first access by this transaction */
 		jh->b_modified = 0;
 
 		JBUFFER_TRACE(jh, "set next transaction");
+		spin_lock(&journal->j_list_lock);
 		jh->b_next_transaction = transaction;
 	}
 	spin_unlock(&journal->j_list_lock);