linux-kernel - [PATCH] vfs: replace WARN(down_read_trylock, ...) abuse with proper asserts

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Date: Sun,  2 Jun 2024 14:37:19 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH] vfs: replace WARN(down_read_trylock, ...) abuse with proper asserts

Note the macro used here works regardless of LOCKDEP.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---
 fs/dcache.c      | 2 +-
 fs/quota/dquot.c | 8 ++------
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 407095188f83..a0a944fd3a1c 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1548,7 +1548,7 @@ void shrink_dcache_for_umount(struct super_block *sb)
 {
 	struct dentry *dentry;
 
-	WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
+	rwsem_assert_held_write(&sb->s_umount);
 
 	dentry = sb->s_root;
 	sb->s_root = NULL;
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 627eb2f72ef3..a2b256dac36e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2246,9 +2246,7 @@ int dquot_disable(struct super_block *sb, int type, unsigned int flags)
 	int cnt;
 	struct quota_info *dqopt = sb_dqopt(sb);
 
-	/* s_umount should be held in exclusive mode */
-	if (WARN_ON_ONCE(down_read_trylock(&sb->s_umount)))
-		up_read(&sb->s_umount);
+	rwsem_assert_held_write(&sb->s_umount);
 
 	/* Cannot turn off usage accounting without turning off limits, or
 	 * suspend quotas and simultaneously turn quotas off. */
@@ -2510,9 +2508,7 @@ int dquot_resume(struct super_block *sb, int type)
 	int ret = 0, cnt;
 	unsigned int flags;
 
-	/* s_umount should be held in exclusive mode */
-	if (WARN_ON_ONCE(down_read_trylock(&sb->s_umount)))
-		up_read(&sb->s_umount);
+	rwsem_assert_held_write(&sb->s_umount);
 
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		if (type != -1 && cnt != type)
-- 
2.39.2