From d699ae4fc27496d01e8bc5ab2106bd79d1e7be92 Mon Sep 17 00:00:00 2001 From: Alexander Lochmann Date: Thu, 11 Feb 2021 10:51:55 +0100 Subject: ext4: updated locking documentation for journal_t Some members of transaction_t are allowed to be read without any lock being held if consistency doesn't matter. Based on LockDoc's findings, we extended the locking documentation of those members. Each one of them is marked with a short comment: "no lock for quick racy checks". Signed-off-by: Alexander Lochmann Signed-off-by: Horst Schirmeier Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/ad82c7a9-a624-4ed5-5ada-a6410c44c0b3@tu-dortmund.de Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 99d3cd051ac3..74710bb231a6 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -768,7 +768,8 @@ enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY}; struct journal_s { /** - * @j_flags: General journaling state flags [j_state_lock] + * @j_flags: General journaling state flags [j_state_lock, + * no lock for quick racy checks] */ unsigned long j_flags; @@ -808,7 +809,8 @@ struct journal_s /** * @j_barrier_count: * - * Number of processes waiting to create a barrier lock [j_state_lock] + * Number of processes waiting to create a barrier lock [j_state_lock, + * no lock for quick racy checks] */ int j_barrier_count; @@ -821,7 +823,8 @@ struct journal_s * @j_running_transaction: * * Transactions: The current running transaction... - * [j_state_lock] [caller holding open handle] + * [j_state_lock, no lock for quick racy checks] [caller holding + * open handle] */ transaction_t *j_running_transaction; @@ -1033,7 +1036,7 @@ struct journal_s * @j_commit_sequence: * * Sequence number of the most recently committed transaction - * [j_state_lock]. + * [j_state_lock, no lock for quick racy checks] */ tid_t j_commit_sequence; @@ -1041,7 +1044,7 @@ struct journal_s * @j_commit_request: * * Sequence number of the most recent transaction wanting commit - * [j_state_lock] + * [j_state_lock, no lock for quick racy checks] */ tid_t j_commit_request; -- cgit v1.2.3 From 3042b1b45c4106feff063932d4fd481c5009dbe1 Mon Sep 17 00:00:00 2001 From: Alexander Lochmann Date: Thu, 11 Feb 2021 18:14:10 +0100 Subject: 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(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 74710bb231a6..b9aa85081a40 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; -- cgit v1.2.3 From d556435156b7970b8ce61b355df558a5168927cc Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 22 Mar 2021 11:21:38 +0100 Subject: jbd2: avoid -Wempty-body warnings Building with 'make W=1' shows a harmless -Wempty-body warning: fs/jbd2/recovery.c: In function 'fc_do_one_pass': fs/jbd2/recovery.c:267:75: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body] 267 | jbd_debug(3, "Fast commit replay failed, err = %d\n", err); | ^ Change the empty dprintk() macros to no_printk(), which avoids this warning and adds format string checking. Signed-off-by: Arnd Bergmann Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20210322102152.95684-1-arnd@kernel.org Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index b9aa85081a40..db0e1920cb12 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -61,7 +61,7 @@ void __jbd2_debug(int level, const char *file, const char *func, #define jbd_debug(n, fmt, a...) \ __jbd2_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a) #else -#define jbd_debug(n, fmt, a...) /**/ +#define jbd_debug(n, fmt, a...) no_printk(fmt, ##a) #endif extern void *jbd2_alloc(size_t size, gfp_t flags); -- cgit v1.2.3