linux-kernel - [RFC PATCH 2/2] jbd2: reset fast commit offset only after fs cleanup is done

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Date: Tue, 21 May 2024 16:45:35 +0100
From: "Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
To: Theodore Ts'o <tytso@....edu>,
	Andreas Dilger <adilger@...ger.ca>,
	Jan Kara <jack@...e.com>
Cc: linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
Subject: [RFC PATCH 2/2] jbd2: reset fast commit offset only after fs cleanup is done

When doing a journal commit, the fast journal offset (journal->j_fc_off) is
set to zero too early in the process.  Since ext4 filesystem calls function
jbd2_fc_release_bufs() in its j_fc_cleanup_callback (ext4_fc_cleanup()),
that call will be a no-op exactly because the offset is zero.

Move the fast commit offset further down in the journal commit code, until
it's mostly done, immediately before clearing the on-going commit flags.

Signed-off-by: Luis Henriques (SUSE) <luis.henriques@...ux.dev>
---
 fs/jbd2/commit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 75ea4e9a5cab..88b834c7c9c9 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -435,7 +435,6 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 			commit_transaction->t_tid);
 
 	write_lock(&journal->j_state_lock);
-	journal->j_fc_off = 0;
 	J_ASSERT(commit_transaction->t_state == T_RUNNING);
 	commit_transaction->t_state = T_LOCKED;
 
@@ -1133,6 +1132,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 		  journal->j_commit_sequence, journal->j_tail_sequence);
 
 	write_lock(&journal->j_state_lock);
+	journal->j_fc_off = 0;
 	journal->j_flags &= ~JBD2_FULL_COMMIT_ONGOING;
 	journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
 	spin_lock(&journal->j_list_lock);