fs: provide rcu-walk aware permission i_ops

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 9 insertions, 1 deletions

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index c936b4912383..fbb324e2bd43 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -325,7 +325,8 @@ struct inode_operations {
         void * (*follow_link) (struct dentry *, struct nameidata *);
         void (*put_link) (struct dentry *, struct nameidata *, void *);
         void (*truncate) (struct inode *);
-        int (*permission) (struct inode *, int, struct nameidata *);
+        int (*permission) (struct inode *, int, unsigned int);
+        int (*check_acl)(struct inode *, int, unsigned int);
         int (*setattr) (struct dentry *, struct iattr *);
         int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
         int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
@@ -414,6 +415,13 @@ otherwise noted.
   permission: called by the VFS to check for access rights on a POSIX-like
         filesystem.
 
+        May be called in rcu-walk mode (flags & IPERM_RCU). If in rcu-walk
+        mode, the filesystem must check the permission without blocking or
+        storing to the inode.
+
+        If a situation is encountered that rcu-walk cannot handle, return
+        -ECHILD and it will be called again in ref-walk mode.
+
   setattr: called by the VFS to set attributes for a file. This method
         is called by chmod(2) and related system calls.