We used LockDoc to derive locking rules for each member
of struct journal_t. Based on those results, we extended
the existing documentation by more members
of struct inode, and updated the existing documentation.
Signed-off-by: Alexander Lochmann <[email protected]>
Signed-off-by: Horst Schirmeier <[email protected]>
---
include/linux/jbd2.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 0f919d5fe84f..c1ba44ca515a 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -585,7 +585,8 @@ struct transaction_s
} t_state;
/*
- * Where in the log does this transaction's commit start? [no locking]
+ * Where in the log does this transaction's commit start?
+ * [journal_t->j_state_lock]
*/
unsigned long t_log_start;
@@ -647,17 +648,17 @@ struct transaction_s
unsigned long t_max_wait;
/*
- * When transaction started
+ * When transaction started [j_state_lock]
*/
unsigned long t_start;
/*
- * When commit was requested
+ * When commit was requested [j_state_lock]
*/
unsigned long t_requested;
/*
- * Checkpointing stats [j_checkpoint_sem]
+ * Checkpointing stats [j_list_lock]
*/
struct transaction_chp_stats_s t_chp_stats;
@@ -744,6 +745,7 @@ jbd2_time_diff(unsigned long start, unsigned long end)
/**
* struct journal_s - The journal_s type is the concrete type associated with
* journal_t.
+ * (Locking Documentation improved by LockDoc)
*/
struct journal_s
{
@@ -762,6 +764,7 @@ struct journal_s
/**
* @j_sb_buffer: The first part of the superblock buffer.
+ * [j_checkpoint_mutex]
*/
struct buffer_head *j_sb_buffer;
@@ -1015,6 +1018,7 @@ struct journal_s
* @j_commit_interval:
*
* What is the maximum transaction lifetime before we begin a commit?
+ * [super_block->s_umount]
*/
unsigned long j_commit_interval;
@@ -1032,7 +1036,7 @@ struct journal_s
* @j_revoke:
*
* The revoke table - maintains the list of revoked blocks in the
- * current transaction.
+ * current transaction. [j_state_lock]
*/
struct jbd2_revoke_table_s *j_revoke;
--
2.20.1
On Fri 08-03-19 16:06:05, Alexander Lochmann wrote:
> We used LockDoc to derive locking rules for each member
> of struct journal_t. Based on those results, we extended
> the existing documentation by more members
> of struct inode, and updated the existing documentation.
>
> Signed-off-by: Alexander Lochmann <[email protected]>
> Signed-off-by: Horst Schirmeier <[email protected]>
> ---
> include/linux/jbd2.h | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
Thanks for the patch! Some comments below.
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 0f919d5fe84f..c1ba44ca515a 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -585,7 +585,8 @@ struct transaction_s
> } t_state;
>
> /*
> - * Where in the log does this transaction's commit start? [no locking]
> + * Where in the log does this transaction's commit start?
> + * [journal_t->j_state_lock]
> */
> unsigned long t_log_start;
>
> @@ -647,17 +648,17 @@ struct transaction_s
> unsigned long t_max_wait;
>
> /*
> - * When transaction started
> + * When transaction started [j_state_lock]
> */
> unsigned long t_start;
>
> /*
> - * When commit was requested
> + * When commit was requested [j_state_lock]
> */
> unsigned long t_requested;
>
> /*
> - * Checkpointing stats [j_checkpoint_sem]
> + * Checkpointing stats [j_list_lock]
> */
> struct transaction_chp_stats_s t_chp_stats;
>
These look correct to me.
> @@ -762,6 +764,7 @@ struct journal_s
>
> /**
> * @j_sb_buffer: The first part of the superblock buffer.
> + * [j_checkpoint_mutex]
> */
> struct buffer_head *j_sb_buffer;
This isn't true. j_sb_buffer is just initialized in journal_init_common()
and never changed. So there's no lock protecting it.
> @@ -1015,6 +1018,7 @@ struct journal_s
> * @j_commit_interval:
> *
> * What is the maximum transaction lifetime before we begin a commit?
> + * [super_block->s_umount]
> */
> unsigned long j_commit_interval;
Ditto here.
> @@ -1032,7 +1036,7 @@ struct journal_s
> * @j_revoke:
> *
> * The revoke table - maintains the list of revoked blocks in the
> - * current transaction.
> + * current transaction. [j_state_lock]
> */
> struct jbd2_revoke_table_s *j_revoke;
>
This is also not true. The contents of the revoke table itself is protected
by j_revoke_lock. The pointer to current revoke table (i.e. j_revoke
itself) is changed only when the currently running transation is in
T_SWITCH state - a special state where no updates can be happening anymore
and new transaction cannot be running yet either.
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR