fs/notify/vfsmount_mark.c

   1 /*
   2  *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2, or (at your option)
   7  *  any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; see the file COPYING.  If not, write to
  16  *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/mount.h>
  24 #include <linux/mutex.h>
  25 #include <linux/spinlock.h>
  26
  27 #include <linux/atomic.h>
  28
  29 #include <linux/fsnotify_backend.h>
  30 #include "fsnotify.h"
  31
  32 void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
  33 {
  34         fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
  35 }
  36
  37 /*
  38  * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
  39  * any notifier is interested in hearing for this mount point
  40  */
  41 void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
  42 {
  43         struct mount *m = real_mount(mnt);
  44
  45         spin_lock(&mnt->mnt_root->d_lock);
  46         m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
  47         spin_unlock(&mnt->mnt_root->d_lock);
  48 }
  49
  50 void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
  51 {
  52         struct vfsmount *mnt = mark->mnt;
  53         struct mount *m = real_mount(mnt);
  54
  55         BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
  56         assert_spin_locked(&mark->lock);
  57
  58         spin_lock(&mnt->mnt_root->d_lock);
  59
  60         hlist_del_init_rcu(&mark->obj_list);
  61         mark->mnt = NULL;
  62
  63         m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
  64         spin_unlock(&mnt->mnt_root->d_lock);
  65 }
  66
  67 /*
  68  * given a group and vfsmount, find the mark associated with that combination.
  69  * if found take a reference to that mark and return it, else return NULL
  70  */
  71 struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
  72                                                   struct vfsmount *mnt)
  73 {
  74         struct mount *m = real_mount(mnt);
  75         struct fsnotify_mark *mark;
  76
  77         spin_lock(&mnt->mnt_root->d_lock);
  78         mark = fsnotify_find_mark(&m->mnt_fsnotify_marks, group);
  79         spin_unlock(&mnt->mnt_root->d_lock);
  80
  81         return mark;
  82 }
  83
  84 /*
  85  * Attach an initialized mark to a given group and vfsmount.
  86  * These marks may be used for the fsnotify backend to determine which
  87  * event types should be delivered to which groups.
  88  */
  89 int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
  90                                struct fsnotify_group *group, struct vfsmount *mnt,
  91                                int allow_dups)
  92 {
  93         struct mount *m = real_mount(mnt);
  94         int ret;
  95
  96         mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
  97
  98         BUG_ON(!mutex_is_locked(&group->mark_mutex));
  99         assert_spin_locked(&mark->lock);
 100
 101         spin_lock(&mnt->mnt_root->d_lock);
 102         mark->mnt = mnt;
 103         ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, allow_dups);
 104         m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
 105         spin_unlock(&mnt->mnt_root->d_lock);
 106
 107         return ret;
 108 }