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![Shakeel Butt](/assets/img/avatar_default.png)
Currently the fs sysctl inotify/max_user_instances is used to limit the number of inotify instances on the system. For systems running multiple workloads, the per-user namespace sysctl max_inotify_instances can be used to further partition inotify instances. However there is no easy way to set a sensible system level max limit on inotify instances and further partition it between the workloads. It is much easier to charge the underlying resource (i.e. memory) behind the inotify instances to the memcg of the workload and let their memory limits limit the number of inotify instances they can create. With inotify instances charged to memcg, the admin can simply set max_user_instances to INT_MAX and let the memcg limits of the jobs limit their inotify instances. Link: https://lore.kernel.org/r/20201220044608.1258123-1-shakeelb@google.com Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Jan Kara <jack@suse.cz>
164 lines
4.4 KiB
C
164 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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*/
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/srcu.h>
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#include <linux/rculist.h>
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#include <linux/wait.h>
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#include <linux/memcontrol.h>
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#include <linux/fsnotify_backend.h>
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#include "fsnotify.h"
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#include <linux/atomic.h>
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/*
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* Final freeing of a group
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*/
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static void fsnotify_final_destroy_group(struct fsnotify_group *group)
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{
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if (group->ops->free_group_priv)
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group->ops->free_group_priv(group);
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mem_cgroup_put(group->memcg);
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mutex_destroy(&group->mark_mutex);
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kfree(group);
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}
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/*
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* Stop queueing new events for this group. Once this function returns
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* fsnotify_add_event() will not add any new events to the group's queue.
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*/
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void fsnotify_group_stop_queueing(struct fsnotify_group *group)
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{
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spin_lock(&group->notification_lock);
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group->shutdown = true;
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spin_unlock(&group->notification_lock);
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}
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/*
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* Trying to get rid of a group. Remove all marks, flush all events and release
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* the group reference.
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* Note that another thread calling fsnotify_clear_marks_by_group() may still
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* hold a ref to the group.
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*/
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void fsnotify_destroy_group(struct fsnotify_group *group)
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{
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/*
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* Stop queueing new events. The code below is careful enough to not
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* require this but fanotify needs to stop queuing events even before
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* fsnotify_destroy_group() is called and this makes the other callers
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* of fsnotify_destroy_group() to see the same behavior.
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*/
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fsnotify_group_stop_queueing(group);
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/* Clear all marks for this group and queue them for destruction */
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fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_ALL_TYPES_MASK);
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/*
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* Some marks can still be pinned when waiting for response from
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* userspace. Wait for those now. fsnotify_prepare_user_wait() will
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* not succeed now so this wait is race-free.
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*/
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wait_event(group->notification_waitq, !atomic_read(&group->user_waits));
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/*
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* Wait until all marks get really destroyed. We could actually destroy
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* them ourselves instead of waiting for worker to do it, however that
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* would be racy as worker can already be processing some marks before
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* we even entered fsnotify_destroy_group().
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*/
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fsnotify_wait_marks_destroyed();
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/*
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* Since we have waited for fsnotify_mark_srcu in
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* fsnotify_mark_destroy_list() there can be no outstanding event
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* notification against this group. So clearing the notification queue
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* of all events is reliable now.
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*/
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fsnotify_flush_notify(group);
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/*
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* Destroy overflow event (we cannot use fsnotify_destroy_event() as
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* that deliberately ignores overflow events.
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*/
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if (group->overflow_event)
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group->ops->free_event(group->overflow_event);
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fsnotify_put_group(group);
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}
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/*
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* Get reference to a group.
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*/
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void fsnotify_get_group(struct fsnotify_group *group)
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{
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refcount_inc(&group->refcnt);
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}
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/*
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* Drop a reference to a group. Free it if it's through.
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*/
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void fsnotify_put_group(struct fsnotify_group *group)
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{
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if (refcount_dec_and_test(&group->refcnt))
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fsnotify_final_destroy_group(group);
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}
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EXPORT_SYMBOL_GPL(fsnotify_put_group);
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static struct fsnotify_group *__fsnotify_alloc_group(
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const struct fsnotify_ops *ops, gfp_t gfp)
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{
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struct fsnotify_group *group;
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group = kzalloc(sizeof(struct fsnotify_group), gfp);
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if (!group)
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return ERR_PTR(-ENOMEM);
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/* set to 0 when there a no external references to this group */
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refcount_set(&group->refcnt, 1);
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atomic_set(&group->num_marks, 0);
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atomic_set(&group->user_waits, 0);
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spin_lock_init(&group->notification_lock);
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INIT_LIST_HEAD(&group->notification_list);
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init_waitqueue_head(&group->notification_waitq);
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group->max_events = UINT_MAX;
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mutex_init(&group->mark_mutex);
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INIT_LIST_HEAD(&group->marks_list);
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group->ops = ops;
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return group;
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}
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/*
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* Create a new fsnotify_group and hold a reference for the group returned.
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*/
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struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
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{
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return __fsnotify_alloc_group(ops, GFP_KERNEL);
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}
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EXPORT_SYMBOL_GPL(fsnotify_alloc_group);
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/*
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* Create a new fsnotify_group and hold a reference for the group returned.
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*/
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struct fsnotify_group *fsnotify_alloc_user_group(const struct fsnotify_ops *ops)
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{
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return __fsnotify_alloc_group(ops, GFP_KERNEL_ACCOUNT);
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}
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EXPORT_SYMBOL_GPL(fsnotify_alloc_user_group);
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int fsnotify_fasync(int fd, struct file *file, int on)
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{
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struct fsnotify_group *group = file->private_data;
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return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
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}
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