2020-02-13 15:51:53

by Madhuparna Bhowmik

Subject: [PATCH] fs: ext4: mballoc.c: Use built-in RCU list checking

From: Madhuparna Bhowmik <[email protected]>

list_for_each_entry_rcu() has built-in RCU and lock checking.

Pass cond argument to list_for_each_entry_rcu() to silence
false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled
by default.

Signed-off-by: Madhuparna Bhowmik <[email protected]>
---
fs/ext4/mballoc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index a3e2767bdf2f..70418e13e9e8 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4280,7 +4280,7 @@ ext4_mb_discard_lg_preallocations(struct super_block *sb,

spin_lock(&lg->lg_prealloc_lock);
list_for_each_entry_rcu(pa, &lg->lg_prealloc_list[order],
- pa_inode_list) {
+ pa_inode_list, lockdep_is_held(&lg->lg_prealloc_lock)) {
spin_lock(&pa->pa_lock);
if (atomic_read(&pa->pa_count)) {
/*
@@ -4363,7 +4363,7 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac)
/* Add the prealloc space to lg */
spin_lock(&lg->lg_prealloc_lock);
list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
- pa_inode_list) {
+ pa_inode_list, lockdep_is_held(&lg->lg_prealloc_lock)) {
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted) {
spin_unlock(&tmp_pa->pa_lock);
--
2.17.1

2020-03-05 22:24:00

by Theodore Ts'o

Subject: Re: [PATCH] fs: ext4: mballoc.c: Use built-in RCU list checking

On Thu, Feb 13, 2020 at 08:55:58PM +0530, [email protected] wrote:
> From: Madhuparna Bhowmik <[email protected]>
>
> list_for_each_entry_rcu() has built-in RCU and lock checking.
>
> Pass cond argument to list_for_each_entry_rcu() to silence
> false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled
> by default.
>
> Signed-off-by: Madhuparna Bhowmik <[email protected]>

Applied, thanks.

- Ted