From 3042b1b45c4106feff063932d4fd481c5009dbe1 Mon Sep 17 00:00:00 2001 From: Alexander Lochmann Date: Thu, 11 Feb 2021 18:14:10 +0100 Subject: [PATCH] Updated locking documentation for transaction_t Some members of transaction_t are allowed to be read without any lock being held if accessed from the correct context. We used LockDoc's findings to determine those members. Each member of them is marked with a short comment: "no lock needed for jbd2 thread". Signed-off-by: Alexander Lochmann Signed-off-by: Horst Schirmeier Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20210211171410.17984-1-alexander.lochmann@tu-dortmund.de Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 74710bb..b9aa850 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -594,18 +594,22 @@ struct transaction_s */ unsigned long t_log_start; - /* Number of buffers on the t_buffers list [j_list_lock] */ + /* + * Number of buffers on the t_buffers list [j_list_lock, no locks + * needed for jbd2 thread] + */ int t_nr_buffers; /* * Doubly-linked circular list of all buffers reserved but not yet - * modified by this transaction [j_list_lock] + * modified by this transaction [j_list_lock, no locks needed fo + * jbd2 thread] */ struct journal_head *t_reserved_list; /* * Doubly-linked circular list of all metadata buffers owned by this - * transaction [j_list_lock] + * transaction [j_list_lock, no locks needed for jbd2 thread] */ struct journal_head *t_buffers; @@ -629,9 +633,11 @@ struct transaction_s struct journal_head *t_checkpoint_io_list; /* - * Doubly-linked circular list of metadata buffers being shadowed by log - * IO. The IO buffers on the iobuf list and the shadow buffers on this - * list match each other one for one at all times. [j_list_lock] + * Doubly-linked circular list of metadata buffers being + * shadowed by log IO. The IO buffers on the iobuf list and + * the shadow buffers on this list match each other one for + * one at all times. [j_list_lock, no locks needed for jbd2 + * thread] */ struct journal_head *t_shadow_list; -- 2.7.4