Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0-or-later
       2             : /*
       3             :  * Copyright (C) 2022-2023 Oracle.  All Rights Reserved.
       4             :  * Author: Darrick J. Wong <djwong@kernel.org>
       5             :  */
       6             : #ifndef XFS_HOOKS_H_
       7             : #define XFS_HOOKS_H_
       8             : 
       9             : #if defined(CONFIG_XFS_LIVE_HOOKS_SRCU)
      10             : struct xfs_hooks {
      11             :         struct srcu_notifier_head       head;
      12             : };
      13             : #elif defined(CONFIG_XFS_LIVE_HOOKS_BLOCKING)
      14             : struct xfs_hooks {
      15             :         struct blocking_notifier_head   head;
      16             : };
      17             : #else
      18             : struct xfs_hooks { /* empty */ };
      19             : #endif
      20             : 
      21             : /*
      22             :  * If hooks and jump labels are enabled, we use jump labels (aka patching of
      23             :  * the code segment) to avoid the minute overhead of calling an empty notifier
      24             :  * chain when we know there are no callers.  If hooks are enabled without jump
      25             :  * labels, hardwire the predicate to true because calling an empty srcu
      26             :  * notifier chain isn't so expensive.
      27             :  */
      28             : #if defined(CONFIG_JUMP_LABEL) && defined(CONFIG_XFS_LIVE_HOOKS)
      29             : # define DEFINE_STATIC_XFS_HOOK_SWITCH(name) \
      30             :         static DEFINE_STATIC_KEY_FALSE(name)
      31             : # define xfs_hooks_switch_on(name)      static_branch_inc(name)
      32             : # define xfs_hooks_switch_off(name)     static_branch_dec(name)
      33             : # define xfs_hooks_switched_on(name)    static_branch_unlikely(name)
      34             : #elif defined(CONFIG_XFS_LIVE_HOOKS)
      35             : # define DEFINE_STATIC_XFS_HOOK_SWITCH(name)
      36             : # define xfs_hooks_switch_on(name)      ((void)0)
      37             : # define xfs_hooks_switch_off(name)     ((void)0)
      38             : # define xfs_hooks_switched_on(name)    (true)
      39             : #else
      40             : # define DEFINE_STATIC_XFS_HOOK_SWITCH(name)
      41             : # define xfs_hooks_switch_on(name)      ((void)0)
      42             : # define xfs_hooks_switch_off(name)     ((void)0)
      43             : # define xfs_hooks_switched_on(name)    (false)
      44             : #endif /* JUMP_LABEL && XFS_LIVE_HOOKS */
      45             : 
      46             : #ifdef CONFIG_XFS_LIVE_HOOKS
      47             : struct xfs_hook {
      48             :         /* This must come at the start of the structure. */
      49             :         struct notifier_block           nb;
      50             : };
      51             : 
      52             : typedef int (*xfs_hook_fn_t)(struct xfs_hook *hook, unsigned long action,
      53             :                 void *data);
      54             : 
      55             : void xfs_hooks_init(struct xfs_hooks *chain);
      56             : int xfs_hooks_add(struct xfs_hooks *chain, struct xfs_hook *hook);
      57             : void xfs_hooks_del(struct xfs_hooks *chain, struct xfs_hook *hook);
      58             : int xfs_hooks_call(struct xfs_hooks *chain, unsigned long action,
      59             :                 void *priv);
      60             : 
      61             : static inline void xfs_hook_setup(struct xfs_hook *hook, notifier_fn_t fn)
      62             : {
      63    26187673 :         hook->nb.notifier_call = fn;
      64    26187673 :         hook->nb.priority = 0;
      65             : }
      66             : 
      67             : #else
      68             : # define xfs_hooks_init(chain)                  ((void)0)
      69             : # define xfs_hooks_call(chain, val, priv)       (NOTIFY_DONE)
      70             : #endif
      71             : 
      72             : #endif /* XFS_HOOKS_H_ */