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

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

[madhuparnabhowmik10]

From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

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 <madhuparnabhowmik10@gmail.com>
---
 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

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

[Theodore Y. Ts'o]

On Thu, Feb 13, 2020 at 08:55:58PM +0530, madhuparnabhowmik10@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> 
> 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 <madhuparnabhowmik10@gmail.com>

Applied, thanks.

						- Ted