[RFC PATCH v2 3/4] dcache.c: more idiomatic "positives are not allowed" sanity checks

Al Viro
2026-04-02T18:05:17Z

Several functions have BUG_ON/WARN_ON sanity checks that want to verify
that dentry is not positive and instead of looking at ->d_inode (as we
do in all other places that check that) they look at ->d_alias.
Just use the normal helpers instead - that way we no longer even look
at ->d_alias for negative dentries

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/dcache.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 4378eb8a00bb..616a445ec720 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -428,7 +428,7 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)

static void dentry_free(struct dentry *dentry)
{
- WARN_ON(!hlist_unhashed(&dentry->d_alias));
+ WARN_ON(d_really_is_positive(dentry));
if (unlikely(dname_external(dentry))) {
struct external_name *p = external_name(dentry);
if (likely(atomic_dec_and_test(&p->count))) {
@@ -2004,7 +2004,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)

void d_instantiate(struct dentry *entry, struct inode * inode)
{
- BUG_ON(!hlist_unhashed(&entry->d_alias));
+ BUG_ON(d_really_is_positive(entry));
if (inode) {
security_d_instantiate(entry, inode);
spin_lock(&inode->i_lock);
@@ -2024,7 +2024,7 @@ EXPORT_SYMBOL(d_instantiate);
*/
void d_instantiate_new(struct dentry *entry, struct inode *inode)
{
- BUG_ON(!hlist_unhashed(&entry->d_alias));
+ BUG_ON(d_really_is_positive(entry));
BUG_ON(!inode);
lockdep_annotate_inode_mutex_key(inode);
security_d_instantiate(entry, inode);
@@ -2795,7 +2795,7 @@ EXPORT_SYMBOL(d_add);

struct dentry *d_make_persistent(struct dentry *dentry, struct inode *inode)
{
- WARN_ON(!hlist_unhashed(&dentry->d_alias));
+ WARN_ON(d_really_is_positive(dentry));
WARN_ON(!inode);
security_d_instantiate(dentry, inode);
spin_lock(&inode->i_lock);
@@ -3185,7 +3185,7 @@ void d_mark_tmpfile(struct file *file, struct inode *inode)
struct dentry *dentry = file->f_path.dentry;

BUG_ON(dname_external(dentry) ||
- !hlist_unhashed(&dentry->d_alias) ||
+ d_really_is_positive(dentry) ||
!d_unlinked(dentry));
spin_lock(&dentry->d_parent->d_lock);
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
--
2.47.3