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164 lines
4.4 KiB
164 lines
4.4 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <[email protected]> |
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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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