[PATCH] bpf: have bpf_real_inode() take a struct file

[Christian Brauner <brauner@kernel.org>]

bpf_real_inode() must be usable from the bprm_check_security, mmap_file
and file_mprotect hooks for systemd's RestrictFilesystemAccess BPF LSM
program. It should take a file instead. The kfunc landed this cycle so
changing the signature is safe.

Fixes: 9af8c8a54f6e ("bpf: add bpf_real_inode() kfunc")
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/bpf_fs_kfuncs.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/bpf_fs_kfuncs.c b/fs/bpf_fs_kfuncs.c
index 768aca2dc0f0..f941c29d26ef 100644
--- a/fs/bpf_fs_kfuncs.c
+++ b/fs/bpf_fs_kfuncs.c
@@ -360,18 +360,18 @@ __bpf_kfunc int bpf_cgroup_read_xattr(struct cgroup *cgroup, const char *name__s
 #endif /* CONFIG_CGROUPS */
 
 /**
- * bpf_real_inode - get the real inode backing a dentry
- * @dentry: dentry to resolve
+ * bpf_real_inode - get the real inode backing a file
+ * @file: file to resolve
  *
- * If the dentry is on a union/overlay filesystem, return the underlying, real
+ * If the file is on a union/overlay filesystem, return the underlying, real
  * inode that hosts the data.  Otherwise return the inode attached to the
- * dentry itself.
+ * file itself.
  *
- * Return: The real inode backing the dentry, or NULL for a negative dentry.
+ * Return: The real inode backing the file, or NULL.
  */
-__bpf_kfunc struct inode *bpf_real_inode(struct dentry *dentry)
+__bpf_kfunc struct inode *bpf_real_inode(struct file *file)
 {
-	return d_real_inode(dentry);
+	return d_real_inode(file_dentry(file));
 }
 
 __bpf_kfunc_end_defs();

---
base-commit: 5b33fc6492a7b7a62359157db0f92f5b6e9af690
change-id: 20260622-work-bpf-real_inode-c3202dbaf0ab