From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- fs/xfs/xfs_drain.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 fs/xfs/xfs_drain.c (limited to 'fs/xfs/xfs_drain.c') diff --git a/fs/xfs/xfs_drain.c b/fs/xfs/xfs_drain.c new file mode 100644 index 000000000..005a66be4 --- /dev/null +++ b/fs/xfs/xfs_drain.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2022-2023 Oracle. All Rights Reserved. + * Author: Darrick J. Wong + */ +#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_rele. 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_gate); + +void +xfs_drain_wait_disable(void) +{ + static_branch_dec(&xfs_drain_waiter_gate); +} + +void +xfs_drain_wait_enable(void) +{ + static_branch_inc(&xfs_drain_waiter_gate); +} + +void +xfs_defer_drain_init( + struct xfs_defer_drain *dr) +{ + atomic_set(&dr->dr_count, 0); + init_waitqueue_head(&dr->dr_waiters); +} + +void +xfs_defer_drain_free(struct xfs_defer_drain *dr) +{ + ASSERT(atomic_read(&dr->dr_count) == 0); +} + +/* Increase the pending intent count. */ +static inline void xfs_defer_drain_grab(struct xfs_defer_drain *dr) +{ + atomic_inc(&dr->dr_count); +} + +static inline bool has_waiters(struct wait_queue_head *wq_head) +{ + /* + * This memory barrier is paired with the one in set_current_state on + * the waiting side. + */ + smp_mb__after_atomic(); + return waitqueue_active(wq_head); +} + +/* Decrease the pending intent count, and wake any waiters, if appropriate. */ +static inline void xfs_defer_drain_rele(struct xfs_defer_drain *dr) +{ + if (atomic_dec_and_test(&dr->dr_count) && + static_branch_unlikely(&xfs_drain_waiter_gate) && + has_waiters(&dr->dr_waiters)) + wake_up(&dr->dr_waiters); +} + +/* Are there intents pending? */ +static inline bool xfs_defer_drain_busy(struct xfs_defer_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_defer_drain_wait(struct xfs_defer_drain *dr) +{ + return wait_event_killable(dr->dr_waiters, !xfs_defer_drain_busy(dr)); +} + +/* + * Get a passive reference to an AG and declare an intent to update its + * metadata. + */ +struct xfs_perag * +xfs_perag_intent_get( + struct xfs_mount *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + + pag = xfs_perag_get(mp, agno); + if (!pag) + return NULL; + + xfs_perag_intent_hold(pag); + return pag; +} + +/* + * Release our intent to update this AG's metadata, and then release our + * passive ref to the AG. + */ +void +xfs_perag_intent_put( + struct xfs_perag *pag) +{ + xfs_perag_intent_rele(pag); + xfs_perag_put(pag); +} + +/* + * Declare an intent to update AG metadata. Other threads that need exclusive + * access can decide to back off if they see declared intentions. + */ +void +xfs_perag_intent_hold( + struct xfs_perag *pag) +{ + trace_xfs_perag_intent_hold(pag, __return_address); + xfs_defer_drain_grab(&pag->pag_intents_drain); +} + +/* Release our intent to update this AG's metadata. */ +void +xfs_perag_intent_rele( + struct xfs_perag *pag) +{ + trace_xfs_perag_intent_rele(pag, __return_address); + xfs_defer_drain_rele(&pag->pag_intents_drain); +} + +/* + * Wait for the intent update count for this AG to hit zero. + * Callers must not hold any AG header buffers. + */ +int +xfs_perag_intent_drain( + struct xfs_perag *pag) +{ + trace_xfs_perag_wait_intents(pag, __return_address); + return xfs_defer_drain_wait(&pag->pag_intents_drain); +} + +/* Has anyone declared an intent to update this AG? */ +bool +xfs_perag_intent_busy( + struct xfs_perag *pag) +{ + return xfs_defer_drain_busy(&pag->pag_intents_drain); +} -- cgit v1.2.3