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f4edce1afd
We recently shifted this code around, so we're no longer holding the
lock on this path.
Fixes: 755b5bc681
("fsnotify: Remove indirection from mark list addition")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
773 lines
23 KiB
C
773 lines
23 KiB
C
/*
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*
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* fsnotify inode mark locking/lifetime/and refcnting
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*
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* REFCNT:
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* The group->recnt and mark->refcnt tell how many "things" in the kernel
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* currently are referencing the objects. Both kind of objects typically will
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* live inside the kernel with a refcnt of 2, one for its creation and one for
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* the reference a group and a mark hold to each other.
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* If you are holding the appropriate locks, you can take a reference and the
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* object itself is guaranteed to survive until the reference is dropped.
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*
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* LOCKING:
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* There are 3 locks involved with fsnotify inode marks and they MUST be taken
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* in order as follows:
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*
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* group->mark_mutex
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* mark->lock
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* mark->connector->lock
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*
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* group->mark_mutex protects the marks_list anchored inside a given group and
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* each mark is hooked via the g_list. It also protects the groups private
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* data (i.e group limits).
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* mark->lock protects the marks attributes like its masks and flags.
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* Furthermore it protects the access to a reference of the group that the mark
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* is assigned to as well as the access to a reference of the inode/vfsmount
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* that is being watched by the mark.
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*
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* mark->connector->lock protects the list of marks anchored inside an
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* inode / vfsmount and each mark is hooked via the i_list.
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*
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* A list of notification marks relating to inode / mnt is contained in
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* fsnotify_mark_connector. That structure is alive as long as there are any
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* marks in the list and is also protected by fsnotify_mark_srcu. A mark gets
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* detached from fsnotify_mark_connector when last reference to the mark is
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* dropped. Thus having mark reference is enough to protect mark->connector
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* pointer and to make sure fsnotify_mark_connector cannot disappear. Also
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* because we remove mark from g_list before dropping mark reference associated
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* with that, any mark found through g_list is guaranteed to have
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* mark->connector set until we drop group->mark_mutex.
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*
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* LIFETIME:
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* Inode marks survive between when they are added to an inode and when their
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* refcnt==0. Marks are also protected by fsnotify_mark_srcu.
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*
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* The inode mark can be cleared for a number of different reasons including:
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* - The inode is unlinked for the last time. (fsnotify_inode_remove)
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* - The inode is being evicted from cache. (fsnotify_inode_delete)
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* - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes)
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* - Something explicitly requests that it be removed. (fsnotify_destroy_mark)
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* - The fsnotify_group associated with the mark is going away and all such marks
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* need to be cleaned up. (fsnotify_clear_marks_by_group)
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*
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* This has the very interesting property of being able to run concurrently with
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* any (or all) other directions.
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kthread.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/srcu.h>
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#include <linux/atomic.h>
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#include <linux/fsnotify_backend.h>
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#include "fsnotify.h"
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#define FSNOTIFY_REAPER_DELAY (1) /* 1 jiffy */
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struct srcu_struct fsnotify_mark_srcu;
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struct kmem_cache *fsnotify_mark_connector_cachep;
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static DEFINE_SPINLOCK(destroy_lock);
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static LIST_HEAD(destroy_list);
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static struct fsnotify_mark_connector *connector_destroy_list;
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static void fsnotify_mark_destroy_workfn(struct work_struct *work);
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static DECLARE_DELAYED_WORK(reaper_work, fsnotify_mark_destroy_workfn);
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static void fsnotify_connector_destroy_workfn(struct work_struct *work);
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static DECLARE_WORK(connector_reaper_work, fsnotify_connector_destroy_workfn);
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void fsnotify_get_mark(struct fsnotify_mark *mark)
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{
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WARN_ON_ONCE(!atomic_read(&mark->refcnt));
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atomic_inc(&mark->refcnt);
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}
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/*
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* Get mark reference when we found the mark via lockless traversal of object
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* list. Mark can be already removed from the list by now and on its way to be
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* destroyed once SRCU period ends.
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*/
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static bool fsnotify_get_mark_safe(struct fsnotify_mark *mark)
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{
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return atomic_inc_not_zero(&mark->refcnt);
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}
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static void __fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
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{
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u32 new_mask = 0;
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struct fsnotify_mark *mark;
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assert_spin_locked(&conn->lock);
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hlist_for_each_entry(mark, &conn->list, obj_list) {
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if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)
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new_mask |= mark->mask;
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}
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if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
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conn->inode->i_fsnotify_mask = new_mask;
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else if (conn->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT)
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real_mount(conn->mnt)->mnt_fsnotify_mask = new_mask;
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}
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/*
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* Calculate mask of events for a list of marks. The caller must make sure
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* connector and connector->inode cannot disappear under us. Callers achieve
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* this by holding a mark->lock or mark->group->mark_mutex for a mark on this
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* list.
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*/
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void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
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{
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if (!conn)
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return;
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spin_lock(&conn->lock);
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__fsnotify_recalc_mask(conn);
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spin_unlock(&conn->lock);
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if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
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__fsnotify_update_child_dentry_flags(conn->inode);
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}
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/* Free all connectors queued for freeing once SRCU period ends */
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static void fsnotify_connector_destroy_workfn(struct work_struct *work)
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{
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struct fsnotify_mark_connector *conn, *free;
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spin_lock(&destroy_lock);
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conn = connector_destroy_list;
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connector_destroy_list = NULL;
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spin_unlock(&destroy_lock);
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synchronize_srcu(&fsnotify_mark_srcu);
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while (conn) {
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free = conn;
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conn = conn->destroy_next;
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kmem_cache_free(fsnotify_mark_connector_cachep, free);
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}
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}
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static struct inode *fsnotify_detach_connector_from_object(
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struct fsnotify_mark_connector *conn)
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{
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struct inode *inode = NULL;
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if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE) {
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inode = conn->inode;
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rcu_assign_pointer(inode->i_fsnotify_marks, NULL);
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inode->i_fsnotify_mask = 0;
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conn->inode = NULL;
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conn->flags &= ~FSNOTIFY_OBJ_TYPE_INODE;
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} else if (conn->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
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rcu_assign_pointer(real_mount(conn->mnt)->mnt_fsnotify_marks,
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NULL);
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real_mount(conn->mnt)->mnt_fsnotify_mask = 0;
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conn->mnt = NULL;
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conn->flags &= ~FSNOTIFY_OBJ_TYPE_VFSMOUNT;
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}
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return inode;
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}
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static void fsnotify_final_mark_destroy(struct fsnotify_mark *mark)
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{
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struct fsnotify_group *group = mark->group;
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if (WARN_ON_ONCE(!group))
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return;
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group->ops->free_mark(mark);
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fsnotify_put_group(group);
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}
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void fsnotify_put_mark(struct fsnotify_mark *mark)
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{
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struct fsnotify_mark_connector *conn;
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struct inode *inode = NULL;
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bool free_conn = false;
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/* Catch marks that were actually never attached to object */
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if (!mark->connector) {
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if (atomic_dec_and_test(&mark->refcnt))
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fsnotify_final_mark_destroy(mark);
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return;
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}
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/*
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* We have to be careful so that traversals of obj_list under lock can
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* safely grab mark reference.
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*/
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if (!atomic_dec_and_lock(&mark->refcnt, &mark->connector->lock))
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return;
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conn = mark->connector;
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hlist_del_init_rcu(&mark->obj_list);
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if (hlist_empty(&conn->list)) {
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inode = fsnotify_detach_connector_from_object(conn);
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free_conn = true;
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} else {
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__fsnotify_recalc_mask(conn);
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}
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mark->connector = NULL;
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spin_unlock(&conn->lock);
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iput(inode);
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if (free_conn) {
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spin_lock(&destroy_lock);
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conn->destroy_next = connector_destroy_list;
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connector_destroy_list = conn;
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spin_unlock(&destroy_lock);
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queue_work(system_unbound_wq, &connector_reaper_work);
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}
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/*
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* Note that we didn't update flags telling whether inode cares about
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* what's happening with children. We update these flags from
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* __fsnotify_parent() lazily when next event happens on one of our
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* children.
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*/
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spin_lock(&destroy_lock);
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list_add(&mark->g_list, &destroy_list);
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spin_unlock(&destroy_lock);
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queue_delayed_work(system_unbound_wq, &reaper_work,
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FSNOTIFY_REAPER_DELAY);
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}
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bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info)
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{
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struct fsnotify_group *group;
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if (WARN_ON_ONCE(!iter_info->inode_mark && !iter_info->vfsmount_mark))
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return false;
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if (iter_info->inode_mark)
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group = iter_info->inode_mark->group;
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else
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group = iter_info->vfsmount_mark->group;
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/*
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* Since acquisition of mark reference is an atomic op as well, we can
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* be sure this inc is seen before any effect of refcount increment.
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*/
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atomic_inc(&group->user_waits);
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if (iter_info->inode_mark) {
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/* This can fail if mark is being removed */
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if (!fsnotify_get_mark_safe(iter_info->inode_mark))
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goto out_wait;
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}
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if (iter_info->vfsmount_mark) {
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if (!fsnotify_get_mark_safe(iter_info->vfsmount_mark))
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goto out_inode;
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}
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/*
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* Now that both marks are pinned by refcount in the inode / vfsmount
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* lists, we can drop SRCU lock, and safely resume the list iteration
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* once userspace returns.
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*/
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srcu_read_unlock(&fsnotify_mark_srcu, iter_info->srcu_idx);
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return true;
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out_inode:
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if (iter_info->inode_mark)
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fsnotify_put_mark(iter_info->inode_mark);
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out_wait:
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if (atomic_dec_and_test(&group->user_waits) && group->shutdown)
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wake_up(&group->notification_waitq);
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return false;
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}
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void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info)
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{
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struct fsnotify_group *group = NULL;
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iter_info->srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
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if (iter_info->inode_mark) {
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group = iter_info->inode_mark->group;
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fsnotify_put_mark(iter_info->inode_mark);
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}
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if (iter_info->vfsmount_mark) {
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group = iter_info->vfsmount_mark->group;
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fsnotify_put_mark(iter_info->vfsmount_mark);
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}
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/*
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* We abuse notification_waitq on group shutdown for waiting for all
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* marks pinned when waiting for userspace.
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*/
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if (atomic_dec_and_test(&group->user_waits) && group->shutdown)
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wake_up(&group->notification_waitq);
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}
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/*
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* Mark mark as detached, remove it from group list. Mark still stays in object
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* list until its last reference is dropped. Note that we rely on mark being
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* removed from group list before corresponding reference to it is dropped. In
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* particular we rely on mark->connector being valid while we hold
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* group->mark_mutex if we found the mark through g_list.
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*
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* Must be called with group->mark_mutex held. The caller must either hold
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* reference to the mark or be protected by fsnotify_mark_srcu.
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*/
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void fsnotify_detach_mark(struct fsnotify_mark *mark)
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{
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struct fsnotify_group *group = mark->group;
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WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex));
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WARN_ON_ONCE(!srcu_read_lock_held(&fsnotify_mark_srcu) &&
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atomic_read(&mark->refcnt) < 1 +
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!!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED));
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spin_lock(&mark->lock);
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/* something else already called this function on this mark */
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if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
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spin_unlock(&mark->lock);
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return;
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}
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mark->flags &= ~FSNOTIFY_MARK_FLAG_ATTACHED;
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list_del_init(&mark->g_list);
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spin_unlock(&mark->lock);
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atomic_dec(&group->num_marks);
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/* Drop mark reference acquired in fsnotify_add_mark_locked() */
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fsnotify_put_mark(mark);
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}
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/*
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* Free fsnotify mark. The mark is actually only marked as being freed. The
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* freeing is actually happening only once last reference to the mark is
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* dropped from a workqueue which first waits for srcu period end.
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*
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* Caller must have a reference to the mark or be protected by
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* fsnotify_mark_srcu.
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*/
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void fsnotify_free_mark(struct fsnotify_mark *mark)
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{
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struct fsnotify_group *group = mark->group;
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spin_lock(&mark->lock);
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/* something else already called this function on this mark */
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if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) {
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spin_unlock(&mark->lock);
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return;
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}
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mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE;
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spin_unlock(&mark->lock);
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/*
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* Some groups like to know that marks are being freed. This is a
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* callback to the group function to let it know that this mark
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* is being freed.
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*/
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if (group->ops->freeing_mark)
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group->ops->freeing_mark(mark, group);
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}
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void fsnotify_destroy_mark(struct fsnotify_mark *mark,
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struct fsnotify_group *group)
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{
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mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
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fsnotify_detach_mark(mark);
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mutex_unlock(&group->mark_mutex);
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fsnotify_free_mark(mark);
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}
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/*
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* Sorting function for lists of fsnotify marks.
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*
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* Fanotify supports different notification classes (reflected as priority of
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* notification group). Events shall be passed to notification groups in
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* decreasing priority order. To achieve this marks in notification lists for
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* inodes and vfsmounts are sorted so that priorities of corresponding groups
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* are descending.
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*
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* Furthermore correct handling of the ignore mask requires processing inode
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* and vfsmount marks of each group together. Using the group address as
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* further sort criterion provides a unique sorting order and thus we can
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* merge inode and vfsmount lists of marks in linear time and find groups
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* present in both lists.
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*
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* A return value of 1 signifies that b has priority over a.
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* A return value of 0 signifies that the two marks have to be handled together.
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* A return value of -1 signifies that a has priority over b.
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*/
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int fsnotify_compare_groups(struct fsnotify_group *a, struct fsnotify_group *b)
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{
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if (a == b)
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return 0;
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if (!a)
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return 1;
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if (!b)
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return -1;
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if (a->priority < b->priority)
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return 1;
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if (a->priority > b->priority)
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return -1;
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if (a < b)
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return 1;
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return -1;
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}
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static int fsnotify_attach_connector_to_object(
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struct fsnotify_mark_connector __rcu **connp,
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struct inode *inode,
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struct vfsmount *mnt)
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{
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struct fsnotify_mark_connector *conn;
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conn = kmem_cache_alloc(fsnotify_mark_connector_cachep, GFP_KERNEL);
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if (!conn)
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return -ENOMEM;
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spin_lock_init(&conn->lock);
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INIT_HLIST_HEAD(&conn->list);
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if (inode) {
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conn->flags = FSNOTIFY_OBJ_TYPE_INODE;
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conn->inode = igrab(inode);
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} else {
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conn->flags = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
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conn->mnt = mnt;
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}
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/*
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* cmpxchg() provides the barrier so that readers of *connp can see
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* only initialized structure
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*/
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if (cmpxchg(connp, NULL, conn)) {
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/* Someone else created list structure for us */
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if (inode)
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iput(inode);
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kmem_cache_free(fsnotify_mark_connector_cachep, conn);
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}
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return 0;
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}
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/*
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* Get mark connector, make sure it is alive and return with its lock held.
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* This is for users that get connector pointer from inode or mount. Users that
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* hold reference to a mark on the list may directly lock connector->lock as
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* they are sure list cannot go away under them.
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*/
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static struct fsnotify_mark_connector *fsnotify_grab_connector(
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struct fsnotify_mark_connector __rcu **connp)
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{
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struct fsnotify_mark_connector *conn;
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int idx;
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idx = srcu_read_lock(&fsnotify_mark_srcu);
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conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
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if (!conn)
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goto out;
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spin_lock(&conn->lock);
|
|
if (!(conn->flags & (FSNOTIFY_OBJ_TYPE_INODE |
|
|
FSNOTIFY_OBJ_TYPE_VFSMOUNT))) {
|
|
spin_unlock(&conn->lock);
|
|
srcu_read_unlock(&fsnotify_mark_srcu, idx);
|
|
return NULL;
|
|
}
|
|
out:
|
|
srcu_read_unlock(&fsnotify_mark_srcu, idx);
|
|
return conn;
|
|
}
|
|
|
|
/*
|
|
* Add mark into proper place in given list of marks. These marks may be used
|
|
* for the fsnotify backend to determine which event types should be delivered
|
|
* to which group and for which inodes. These marks are ordered according to
|
|
* priority, highest number first, and then by the group's location in memory.
|
|
*/
|
|
static int fsnotify_add_mark_list(struct fsnotify_mark *mark,
|
|
struct inode *inode, struct vfsmount *mnt,
|
|
int allow_dups)
|
|
{
|
|
struct fsnotify_mark *lmark, *last = NULL;
|
|
struct fsnotify_mark_connector *conn;
|
|
struct fsnotify_mark_connector __rcu **connp;
|
|
int cmp;
|
|
int err = 0;
|
|
|
|
if (WARN_ON(!inode && !mnt))
|
|
return -EINVAL;
|
|
if (inode)
|
|
connp = &inode->i_fsnotify_marks;
|
|
else
|
|
connp = &real_mount(mnt)->mnt_fsnotify_marks;
|
|
restart:
|
|
spin_lock(&mark->lock);
|
|
conn = fsnotify_grab_connector(connp);
|
|
if (!conn) {
|
|
spin_unlock(&mark->lock);
|
|
err = fsnotify_attach_connector_to_object(connp, inode, mnt);
|
|
if (err)
|
|
return err;
|
|
goto restart;
|
|
}
|
|
|
|
/* is mark the first mark? */
|
|
if (hlist_empty(&conn->list)) {
|
|
hlist_add_head_rcu(&mark->obj_list, &conn->list);
|
|
goto added;
|
|
}
|
|
|
|
/* should mark be in the middle of the current list? */
|
|
hlist_for_each_entry(lmark, &conn->list, obj_list) {
|
|
last = lmark;
|
|
|
|
if ((lmark->group == mark->group) &&
|
|
(lmark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) &&
|
|
!allow_dups) {
|
|
err = -EEXIST;
|
|
goto out_err;
|
|
}
|
|
|
|
cmp = fsnotify_compare_groups(lmark->group, mark->group);
|
|
if (cmp >= 0) {
|
|
hlist_add_before_rcu(&mark->obj_list, &lmark->obj_list);
|
|
goto added;
|
|
}
|
|
}
|
|
|
|
BUG_ON(last == NULL);
|
|
/* mark should be the last entry. last is the current last entry */
|
|
hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);
|
|
added:
|
|
mark->connector = conn;
|
|
out_err:
|
|
spin_unlock(&conn->lock);
|
|
spin_unlock(&mark->lock);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Attach an initialized mark to a given group and fs object.
|
|
* These marks may be used for the fsnotify backend to determine which
|
|
* event types should be delivered to which group.
|
|
*/
|
|
int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct inode *inode,
|
|
struct vfsmount *mnt, int allow_dups)
|
|
{
|
|
struct fsnotify_group *group = mark->group;
|
|
int ret = 0;
|
|
|
|
BUG_ON(inode && mnt);
|
|
BUG_ON(!inode && !mnt);
|
|
BUG_ON(!mutex_is_locked(&group->mark_mutex));
|
|
|
|
/*
|
|
* LOCKING ORDER!!!!
|
|
* group->mark_mutex
|
|
* mark->lock
|
|
* mark->connector->lock
|
|
*/
|
|
spin_lock(&mark->lock);
|
|
mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE | FSNOTIFY_MARK_FLAG_ATTACHED;
|
|
|
|
list_add(&mark->g_list, &group->marks_list);
|
|
atomic_inc(&group->num_marks);
|
|
fsnotify_get_mark(mark); /* for g_list */
|
|
spin_unlock(&mark->lock);
|
|
|
|
ret = fsnotify_add_mark_list(mark, inode, mnt, allow_dups);
|
|
if (ret)
|
|
goto err;
|
|
|
|
if (mark->mask)
|
|
fsnotify_recalc_mask(mark->connector);
|
|
|
|
return ret;
|
|
err:
|
|
mark->flags &= ~(FSNOTIFY_MARK_FLAG_ALIVE |
|
|
FSNOTIFY_MARK_FLAG_ATTACHED);
|
|
list_del_init(&mark->g_list);
|
|
atomic_dec(&group->num_marks);
|
|
|
|
fsnotify_put_mark(mark);
|
|
return ret;
|
|
}
|
|
|
|
int fsnotify_add_mark(struct fsnotify_mark *mark, struct inode *inode,
|
|
struct vfsmount *mnt, int allow_dups)
|
|
{
|
|
int ret;
|
|
struct fsnotify_group *group = mark->group;
|
|
|
|
mutex_lock(&group->mark_mutex);
|
|
ret = fsnotify_add_mark_locked(mark, inode, mnt, allow_dups);
|
|
mutex_unlock(&group->mark_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Given a list of marks, find the mark associated with given group. If found
|
|
* take a reference to that mark and return it, else return NULL.
|
|
*/
|
|
struct fsnotify_mark *fsnotify_find_mark(
|
|
struct fsnotify_mark_connector __rcu **connp,
|
|
struct fsnotify_group *group)
|
|
{
|
|
struct fsnotify_mark_connector *conn;
|
|
struct fsnotify_mark *mark;
|
|
|
|
conn = fsnotify_grab_connector(connp);
|
|
if (!conn)
|
|
return NULL;
|
|
|
|
hlist_for_each_entry(mark, &conn->list, obj_list) {
|
|
if (mark->group == group &&
|
|
(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
|
|
fsnotify_get_mark(mark);
|
|
spin_unlock(&conn->lock);
|
|
return mark;
|
|
}
|
|
}
|
|
spin_unlock(&conn->lock);
|
|
return NULL;
|
|
}
|
|
|
|
/* Clear any marks in a group with given type */
|
|
void fsnotify_clear_marks_by_group(struct fsnotify_group *group,
|
|
unsigned int type)
|
|
{
|
|
struct fsnotify_mark *lmark, *mark;
|
|
LIST_HEAD(to_free);
|
|
struct list_head *head = &to_free;
|
|
|
|
/* Skip selection step if we want to clear all marks. */
|
|
if (type == FSNOTIFY_OBJ_ALL_TYPES) {
|
|
head = &group->marks_list;
|
|
goto clear;
|
|
}
|
|
/*
|
|
* We have to be really careful here. Anytime we drop mark_mutex, e.g.
|
|
* fsnotify_clear_marks_by_inode() can come and free marks. Even in our
|
|
* to_free list so we have to use mark_mutex even when accessing that
|
|
* list. And freeing mark requires us to drop mark_mutex. So we can
|
|
* reliably free only the first mark in the list. That's why we first
|
|
* move marks to free to to_free list in one go and then free marks in
|
|
* to_free list one by one.
|
|
*/
|
|
mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
|
|
list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
|
|
if (mark->connector->flags & type)
|
|
list_move(&mark->g_list, &to_free);
|
|
}
|
|
mutex_unlock(&group->mark_mutex);
|
|
|
|
clear:
|
|
while (1) {
|
|
mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
|
|
if (list_empty(head)) {
|
|
mutex_unlock(&group->mark_mutex);
|
|
break;
|
|
}
|
|
mark = list_first_entry(head, struct fsnotify_mark, g_list);
|
|
fsnotify_get_mark(mark);
|
|
fsnotify_detach_mark(mark);
|
|
mutex_unlock(&group->mark_mutex);
|
|
fsnotify_free_mark(mark);
|
|
fsnotify_put_mark(mark);
|
|
}
|
|
}
|
|
|
|
/* Destroy all marks attached to inode / vfsmount */
|
|
void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu **connp)
|
|
{
|
|
struct fsnotify_mark_connector *conn;
|
|
struct fsnotify_mark *mark, *old_mark = NULL;
|
|
struct inode *inode;
|
|
|
|
conn = fsnotify_grab_connector(connp);
|
|
if (!conn)
|
|
return;
|
|
/*
|
|
* We have to be careful since we can race with e.g.
|
|
* fsnotify_clear_marks_by_group() and once we drop the conn->lock, the
|
|
* list can get modified. However we are holding mark reference and
|
|
* thus our mark cannot be removed from obj_list so we can continue
|
|
* iteration after regaining conn->lock.
|
|
*/
|
|
hlist_for_each_entry(mark, &conn->list, obj_list) {
|
|
fsnotify_get_mark(mark);
|
|
spin_unlock(&conn->lock);
|
|
if (old_mark)
|
|
fsnotify_put_mark(old_mark);
|
|
old_mark = mark;
|
|
fsnotify_destroy_mark(mark, mark->group);
|
|
spin_lock(&conn->lock);
|
|
}
|
|
/*
|
|
* Detach list from object now so that we don't pin inode until all
|
|
* mark references get dropped. It would lead to strange results such
|
|
* as delaying inode deletion or blocking unmount.
|
|
*/
|
|
inode = fsnotify_detach_connector_from_object(conn);
|
|
spin_unlock(&conn->lock);
|
|
if (old_mark)
|
|
fsnotify_put_mark(old_mark);
|
|
iput(inode);
|
|
}
|
|
|
|
/*
|
|
* Nothing fancy, just initialize lists and locks and counters.
|
|
*/
|
|
void fsnotify_init_mark(struct fsnotify_mark *mark,
|
|
struct fsnotify_group *group)
|
|
{
|
|
memset(mark, 0, sizeof(*mark));
|
|
spin_lock_init(&mark->lock);
|
|
atomic_set(&mark->refcnt, 1);
|
|
fsnotify_get_group(group);
|
|
mark->group = group;
|
|
}
|
|
|
|
/*
|
|
* Destroy all marks in destroy_list, waits for SRCU period to finish before
|
|
* actually freeing marks.
|
|
*/
|
|
static void fsnotify_mark_destroy_workfn(struct work_struct *work)
|
|
{
|
|
struct fsnotify_mark *mark, *next;
|
|
struct list_head private_destroy_list;
|
|
|
|
spin_lock(&destroy_lock);
|
|
/* exchange the list head */
|
|
list_replace_init(&destroy_list, &private_destroy_list);
|
|
spin_unlock(&destroy_lock);
|
|
|
|
synchronize_srcu(&fsnotify_mark_srcu);
|
|
|
|
list_for_each_entry_safe(mark, next, &private_destroy_list, g_list) {
|
|
list_del_init(&mark->g_list);
|
|
fsnotify_final_mark_destroy(mark);
|
|
}
|
|
}
|
|
|
|
/* Wait for all marks queued for destruction to be actually destroyed */
|
|
void fsnotify_wait_marks_destroyed(void)
|
|
{
|
|
flush_delayed_work(&reaper_work);
|
|
}
|