>From 00168e5ef68e927fad169d8fc54d10e066b6883b Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 18 Mar 2015 14:29:13 +0100 Subject: [PATCH 5/5] jbd2: Speedup jbd2_journal_dirty_metadata() It is often the case that we mark buffer as having dirty metadata when the buffer is already in that state (frequent for bitmaps, inode table blocks, superblock). Thus it is unnecessary to contend on grabbing journal head reference and bh_state lock. Avoid that by checking whether any modification to the buffer is needed before grabbing any locks or references. Signed-off-by: Jan Kara --- fs/jbd2/transaction.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index a91f639af6c3..7a3ffd0c855f 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1290,8 +1290,6 @@ void jbd2_buffer_abort_trigger(struct journal_head *jh, triggers->t_abort(triggers, jh2bh(jh)); } - - /** * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata * @handle: transaction to add buffer to. @@ -1325,12 +1323,36 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) WARN_ON(!transaction); if (is_handle_aborted(handle)) return -EROFS; - journal = transaction->t_journal; - jh = jbd2_journal_grab_journal_head(bh); - if (!jh) { + if (!buffer_jbd(bh)) { ret = -EUCLEAN; goto out; } + /* + * We don't grab jh reference here since the buffer must be part + * of the running transaction. + */ + jh = bh2jh(bh); + J_ASSERT_JH(jh, jh->b_transaction == transaction || + jh->b_next_transaction == transaction); + if (jh->b_modified == 1) { + /* + * If it's in our transaction it must be in BJ_Metadata list. + * The assertion is unreliable since we may see jh in + * inconsistent state unless we grab bh_state lock. But this + * is crutial to catch bugs so let's do a reliable check until + * the lockless handling is fully proven. + */ + if (jh->b_transaction == transaction && + jh->b_jlist != BJ_Metadata) { + jbd_lock_bh_state(bh); + J_ASSERT_JH(jh, jh->b_transaction != transaction || + jh->b_jlist == BJ_Metadata); + jbd_lock_bh_state(bh); + } + goto out; + } + + journal = transaction->t_journal; jbd_debug(5, "journal_head %p\n", jh); JBUFFER_TRACE(jh, "entry"); @@ -1421,7 +1443,6 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) spin_unlock(&journal->j_list_lock); out_unlock_bh: jbd_unlock_bh_state(bh); - jbd2_journal_put_journal_head(jh); out: JBUFFER_TRACE(jh, "exit"); return ret; -- 2.1.4