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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /fs/btrfs/async-thread.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/btrfs/async-thread.c')
-rw-r--r--fs/btrfs/async-thread.c341
1 files changed, 341 insertions, 0 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
new file mode 100644
index 000000000..aac240430
--- /dev/null
+++ b/fs/btrfs/async-thread.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle. All rights reserved.
+ * Copyright (C) 2014 Fujitsu. All rights reserved.
+ */
+
+#include <linux/kthread.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/freezer.h>
+#include "async-thread.h"
+#include "ctree.h"
+
+enum {
+ WORK_DONE_BIT,
+ WORK_ORDER_DONE_BIT,
+};
+
+#define NO_THRESHOLD (-1)
+#define DFT_THRESHOLD (32)
+
+struct btrfs_workqueue {
+ struct workqueue_struct *normal_wq;
+
+ /* File system this workqueue services */
+ struct btrfs_fs_info *fs_info;
+
+ /* List head pointing to ordered work list */
+ struct list_head ordered_list;
+
+ /* Spinlock for ordered_list */
+ spinlock_t list_lock;
+
+ /* Thresholding related variants */
+ atomic_t pending;
+
+ /* Up limit of concurrency workers */
+ int limit_active;
+
+ /* Current number of concurrency workers */
+ int current_active;
+
+ /* Threshold to change current_active */
+ int thresh;
+ unsigned int count;
+ spinlock_t thres_lock;
+};
+
+struct btrfs_fs_info * __pure btrfs_workqueue_owner(const struct btrfs_workqueue *wq)
+{
+ return wq->fs_info;
+}
+
+struct btrfs_fs_info * __pure btrfs_work_owner(const struct btrfs_work *work)
+{
+ return work->wq->fs_info;
+}
+
+bool btrfs_workqueue_normal_congested(const struct btrfs_workqueue *wq)
+{
+ /*
+ * We could compare wq->pending with num_online_cpus()
+ * to support "thresh == NO_THRESHOLD" case, but it requires
+ * moving up atomic_inc/dec in thresh_queue/exec_hook. Let's
+ * postpone it until someone needs the support of that case.
+ */
+ if (wq->thresh == NO_THRESHOLD)
+ return false;
+
+ return atomic_read(&wq->pending) > wq->thresh * 2;
+}
+
+struct btrfs_workqueue *btrfs_alloc_workqueue(struct btrfs_fs_info *fs_info,
+ const char *name, unsigned int flags,
+ int limit_active, int thresh)
+{
+ struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_KERNEL);
+
+ if (!ret)
+ return NULL;
+
+ ret->fs_info = fs_info;
+ ret->limit_active = limit_active;
+ atomic_set(&ret->pending, 0);
+ if (thresh == 0)
+ thresh = DFT_THRESHOLD;
+ /* For low threshold, disabling threshold is a better choice */
+ if (thresh < DFT_THRESHOLD) {
+ ret->current_active = limit_active;
+ ret->thresh = NO_THRESHOLD;
+ } else {
+ /*
+ * For threshold-able wq, let its concurrency grow on demand.
+ * Use minimal max_active at alloc time to reduce resource
+ * usage.
+ */
+ ret->current_active = 1;
+ ret->thresh = thresh;
+ }
+
+ ret->normal_wq = alloc_workqueue("btrfs-%s", flags, ret->current_active,
+ name);
+ if (!ret->normal_wq) {
+ kfree(ret);
+ return NULL;
+ }
+
+ INIT_LIST_HEAD(&ret->ordered_list);
+ spin_lock_init(&ret->list_lock);
+ spin_lock_init(&ret->thres_lock);
+ trace_btrfs_workqueue_alloc(ret, name);
+ return ret;
+}
+
+/*
+ * Hook for threshold which will be called in btrfs_queue_work.
+ * This hook WILL be called in IRQ handler context,
+ * so workqueue_set_max_active MUST NOT be called in this hook
+ */
+static inline void thresh_queue_hook(struct btrfs_workqueue *wq)
+{
+ if (wq->thresh == NO_THRESHOLD)
+ return;
+ atomic_inc(&wq->pending);
+}
+
+/*
+ * Hook for threshold which will be called before executing the work,
+ * This hook is called in kthread content.
+ * So workqueue_set_max_active is called here.
+ */
+static inline void thresh_exec_hook(struct btrfs_workqueue *wq)
+{
+ int new_current_active;
+ long pending;
+ int need_change = 0;
+
+ if (wq->thresh == NO_THRESHOLD)
+ return;
+
+ atomic_dec(&wq->pending);
+ spin_lock(&wq->thres_lock);
+ /*
+ * Use wq->count to limit the calling frequency of
+ * workqueue_set_max_active.
+ */
+ wq->count++;
+ wq->count %= (wq->thresh / 4);
+ if (!wq->count)
+ goto out;
+ new_current_active = wq->current_active;
+
+ /*
+ * pending may be changed later, but it's OK since we really
+ * don't need it so accurate to calculate new_max_active.
+ */
+ pending = atomic_read(&wq->pending);
+ if (pending > wq->thresh)
+ new_current_active++;
+ if (pending < wq->thresh / 2)
+ new_current_active--;
+ new_current_active = clamp_val(new_current_active, 1, wq->limit_active);
+ if (new_current_active != wq->current_active) {
+ need_change = 1;
+ wq->current_active = new_current_active;
+ }
+out:
+ spin_unlock(&wq->thres_lock);
+
+ if (need_change) {
+ workqueue_set_max_active(wq->normal_wq, wq->current_active);
+ }
+}
+
+static void run_ordered_work(struct btrfs_workqueue *wq,
+ struct btrfs_work *self)
+{
+ struct list_head *list = &wq->ordered_list;
+ struct btrfs_work *work;
+ spinlock_t *lock = &wq->list_lock;
+ unsigned long flags;
+ bool free_self = false;
+
+ while (1) {
+ spin_lock_irqsave(lock, flags);
+ if (list_empty(list))
+ break;
+ work = list_entry(list->next, struct btrfs_work,
+ ordered_list);
+ if (!test_bit(WORK_DONE_BIT, &work->flags))
+ break;
+ /*
+ * Orders all subsequent loads after reading WORK_DONE_BIT,
+ * paired with the smp_mb__before_atomic in btrfs_work_helper
+ * this guarantees that the ordered function will see all
+ * updates from ordinary work function.
+ */
+ smp_rmb();
+
+ /*
+ * we are going to call the ordered done function, but
+ * we leave the work item on the list as a barrier so
+ * that later work items that are done don't have their
+ * functions called before this one returns
+ */
+ if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
+ break;
+ trace_btrfs_ordered_sched(work);
+ spin_unlock_irqrestore(lock, flags);
+ work->ordered_func(work);
+
+ /* now take the lock again and drop our item from the list */
+ spin_lock_irqsave(lock, flags);
+ list_del(&work->ordered_list);
+ spin_unlock_irqrestore(lock, flags);
+
+ if (work == self) {
+ /*
+ * This is the work item that the worker is currently
+ * executing.
+ *
+ * The kernel workqueue code guarantees non-reentrancy
+ * of work items. I.e., if a work item with the same
+ * address and work function is queued twice, the second
+ * execution is blocked until the first one finishes. A
+ * work item may be freed and recycled with the same
+ * work function; the workqueue code assumes that the
+ * original work item cannot depend on the recycled work
+ * item in that case (see find_worker_executing_work()).
+ *
+ * Note that different types of Btrfs work can depend on
+ * each other, and one type of work on one Btrfs
+ * filesystem may even depend on the same type of work
+ * on another Btrfs filesystem via, e.g., a loop device.
+ * Therefore, we must not allow the current work item to
+ * be recycled until we are really done, otherwise we
+ * break the above assumption and can deadlock.
+ */
+ free_self = true;
+ } else {
+ /*
+ * We don't want to call the ordered free functions with
+ * the lock held.
+ */
+ work->ordered_free(work);
+ /* NB: work must not be dereferenced past this point. */
+ trace_btrfs_all_work_done(wq->fs_info, work);
+ }
+ }
+ spin_unlock_irqrestore(lock, flags);
+
+ if (free_self) {
+ self->ordered_free(self);
+ /* NB: self must not be dereferenced past this point. */
+ trace_btrfs_all_work_done(wq->fs_info, self);
+ }
+}
+
+static void btrfs_work_helper(struct work_struct *normal_work)
+{
+ struct btrfs_work *work = container_of(normal_work, struct btrfs_work,
+ normal_work);
+ struct btrfs_workqueue *wq = work->wq;
+ int need_order = 0;
+
+ /*
+ * We should not touch things inside work in the following cases:
+ * 1) after work->func() if it has no ordered_free
+ * Since the struct is freed in work->func().
+ * 2) after setting WORK_DONE_BIT
+ * The work may be freed in other threads almost instantly.
+ * So we save the needed things here.
+ */
+ if (work->ordered_func)
+ need_order = 1;
+
+ trace_btrfs_work_sched(work);
+ thresh_exec_hook(wq);
+ work->func(work);
+ if (need_order) {
+ /*
+ * Ensures all memory accesses done in the work function are
+ * ordered before setting the WORK_DONE_BIT. Ensuring the thread
+ * which is going to executed the ordered work sees them.
+ * Pairs with the smp_rmb in run_ordered_work.
+ */
+ smp_mb__before_atomic();
+ set_bit(WORK_DONE_BIT, &work->flags);
+ run_ordered_work(wq, work);
+ } else {
+ /* NB: work must not be dereferenced past this point. */
+ trace_btrfs_all_work_done(wq->fs_info, work);
+ }
+}
+
+void btrfs_init_work(struct btrfs_work *work, btrfs_func_t func,
+ btrfs_func_t ordered_func, btrfs_func_t ordered_free)
+{
+ work->func = func;
+ work->ordered_func = ordered_func;
+ work->ordered_free = ordered_free;
+ INIT_WORK(&work->normal_work, btrfs_work_helper);
+ INIT_LIST_HEAD(&work->ordered_list);
+ work->flags = 0;
+}
+
+void btrfs_queue_work(struct btrfs_workqueue *wq, struct btrfs_work *work)
+{
+ unsigned long flags;
+
+ work->wq = wq;
+ thresh_queue_hook(wq);
+ if (work->ordered_func) {
+ spin_lock_irqsave(&wq->list_lock, flags);
+ list_add_tail(&work->ordered_list, &wq->ordered_list);
+ spin_unlock_irqrestore(&wq->list_lock, flags);
+ }
+ trace_btrfs_work_queued(work);
+ queue_work(wq->normal_wq, &work->normal_work);
+}
+
+void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
+{
+ if (!wq)
+ return;
+ destroy_workqueue(wq->normal_wq);
+ trace_btrfs_workqueue_destroy(wq);
+ kfree(wq);
+}
+
+void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active)
+{
+ if (wq)
+ wq->limit_active = limit_active;
+}
+
+void btrfs_flush_workqueue(struct btrfs_workqueue *wq)
+{
+ flush_workqueue(wq->normal_wq);
+}