66 lines
2.1 KiB
C
66 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (c) 2022-2024 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <djwong@kernel.org>
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*/
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#ifndef XFS_HOOKS_H_
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#define XFS_HOOKS_H_
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#ifdef CONFIG_XFS_LIVE_HOOKS
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struct xfs_hooks {
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struct blocking_notifier_head head;
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};
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/*
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* If jump labels are enabled in Kconfig, the static key uses nop sleds and
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* code patching to eliminate the overhead of taking the rwsem in
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* blocking_notifier_call_chain when there are no hooks configured. If not,
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* the static key per-call overhead is an atomic read. Most arches that can
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* handle XFS also support jump labels.
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*
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* Note: Patching the kernel code requires taking the cpu hotplug lock. Other
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* parts of the kernel allocate memory with that lock held, which means that
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* XFS callers cannot hold any locks that might be used by memory reclaim or
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* writeback when calling the static_branch_{inc,dec} functions.
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*/
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# define DEFINE_STATIC_XFS_HOOK_SWITCH(name) \
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static DEFINE_STATIC_KEY_FALSE(name)
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# define xfs_hooks_switch_on(name) static_branch_inc(name)
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# define xfs_hooks_switch_off(name) static_branch_dec(name)
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# define xfs_hooks_switched_on(name) static_branch_unlikely(name)
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struct xfs_hook {
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/* This must come at the start of the structure. */
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struct notifier_block nb;
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};
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typedef int (*xfs_hook_fn_t)(struct xfs_hook *hook, unsigned long action,
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void *data);
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void xfs_hooks_init(struct xfs_hooks *chain);
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int xfs_hooks_add(struct xfs_hooks *chain, struct xfs_hook *hook);
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void xfs_hooks_del(struct xfs_hooks *chain, struct xfs_hook *hook);
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int xfs_hooks_call(struct xfs_hooks *chain, unsigned long action,
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void *priv);
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static inline void xfs_hook_setup(struct xfs_hook *hook, notifier_fn_t fn)
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{
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hook->nb.notifier_call = fn;
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hook->nb.priority = 0;
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}
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#else
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struct xfs_hooks { /* empty */ };
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# define DEFINE_STATIC_XFS_HOOK_SWITCH(name)
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# define xfs_hooks_switch_on(name) ((void)0)
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# define xfs_hooks_switch_off(name) ((void)0)
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# define xfs_hooks_switched_on(name) (false)
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# define xfs_hooks_init(chain) ((void)0)
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# define xfs_hooks_call(chain, val, priv) (NOTIFY_DONE)
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#endif
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#endif /* XFS_HOOKS_H_ */
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