// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (c) 2022-2024 Oracle. All Rights Reserved. * Author: Darrick J. Wong <[email protected]> */ #ifndef XFS_HOOKS_H_ #define XFS_HOOKS_H_ #ifdef CONFIG_XFS_LIVE_HOOKS struct xfs_hooks { … }; /* * If jump labels are enabled in Kconfig, the static key uses nop sleds and * code patching to eliminate the overhead of taking the rwsem in * blocking_notifier_call_chain when there are no hooks configured. If not, * the static key per-call overhead is an atomic read. Most arches that can * handle XFS also support jump labels. * * Note: Patching the kernel code requires taking the cpu hotplug lock. Other * parts of the kernel allocate memory with that lock held, which means that * XFS callers cannot hold any locks that might be used by memory reclaim or * writeback when calling the static_branch_{inc,dec} functions. */ #define DEFINE_STATIC_XFS_HOOK_SWITCH(name) … #define xfs_hooks_switch_on(name) … #define xfs_hooks_switch_off(name) … #define xfs_hooks_switched_on(name) … struct xfs_hook { … }; xfs_hook_fn_t; void xfs_hooks_init(struct xfs_hooks *chain); int xfs_hooks_add(struct xfs_hooks *chain, struct xfs_hook *hook); void xfs_hooks_del(struct xfs_hooks *chain, struct xfs_hook *hook); int xfs_hooks_call(struct xfs_hooks *chain, unsigned long action, void *priv); static inline void xfs_hook_setup(struct xfs_hook *hook, notifier_fn_t fn) { … } #else struct xfs_hooks { /* empty */ }; #define DEFINE_STATIC_XFS_HOOK_SWITCH … #define xfs_hooks_switch_on … #define xfs_hooks_switch_off … #define xfs_hooks_switched_on … #define xfs_hooks_init … #define xfs_hooks_call … #endif #endif /* XFS_HOOKS_H_ */
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