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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2022 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_ag.h"
#include "xfs_trace.h"
/*
* Use a static key here to reduce the overhead of xfs_drain_drop. If the
* compiler supports jump labels, the static branch will be replaced by a nop
* sled when there are no xfs_drain_wait callers. Online fsck is currently
* the only caller, so this is a reasonable tradeoff.
*
* 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.
*/
static DEFINE_STATIC_KEY_FALSE(xfs_drain_waiter_hook);
void
xfs_drain_wait_disable(void)
{
static_branch_dec(&xfs_drain_waiter_hook);
}
void
xfs_drain_wait_enable(void)
{
static_branch_inc(&xfs_drain_waiter_hook);
}
void
xfs_drain_init(
struct xfs_drain *dr)
{
atomic_set(&dr->dr_count, 0);
init_waitqueue_head(&dr->dr_waiters);
}
void
xfs_drain_free(struct xfs_drain *dr)
{
ASSERT(atomic_read(&dr->dr_count) == 0);
}
/* Increase the pending intent count. */
static inline void xfs_drain_bump(struct xfs_drain *dr)
{
atomic_inc(&dr->dr_count);
}
/* Decrease the pending intent count, and wake any waiters, if appropriate. */
static inline void xfs_drain_drop(struct xfs_drain *dr)
{
if (atomic_dec_and_test(&dr->dr_count) &&
static_branch_unlikely(&xfs_drain_waiter_hook))
wake_up(&dr->dr_waiters);
}
/* Are there work items pending? */
static inline bool xfs_drain_busy(struct xfs_drain *dr)
{
return atomic_read(&dr->dr_count) > 0;
}
/*
* Wait for the pending intent count for a drain to hit zero.
*
* Callers must not hold any locks that would prevent intents from being
* finished.
*/
static inline int xfs_drain_wait(struct xfs_drain *dr)
{
return wait_event_killable(dr->dr_waiters, !xfs_drain_busy(dr));
}
/* Add an item to the pending count. */
void
xfs_perag_bump_intents(
struct xfs_perag *pag)
{
trace_xfs_perag_bump_intents(pag, __return_address);
xfs_drain_bump(&pag->pag_intents);
}
/* Remove an item from the pending count. */
void
xfs_perag_drop_intents(
struct xfs_perag *pag)
{
trace_xfs_perag_drop_intents(pag, __return_address);
xfs_drain_drop(&pag->pag_intents);
}
/*
* Wait for the pending intent count for AG metadata to hit zero.
* Callers must not hold any AG header buffers.
*/
int
xfs_perag_drain_intents(
struct xfs_perag *pag)
{
trace_xfs_perag_wait_intents(pag, __return_address);
return xfs_drain_wait(&pag->pag_intents);
}
/* Might someone else be processing intents for this AG? */
bool
xfs_perag_intents_busy(
struct xfs_perag *pag)
{
return xfs_drain_busy(&pag->pag_intents);
}
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