linux/fs/notify/inode_mark.c
<<
>>
Prefs
   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/mutex.h>
  24#include <linux/spinlock.h>
  25
  26#include <linux/atomic.h>
  27
  28#include <linux/fsnotify_backend.h>
  29#include "fsnotify.h"
  30
  31#include "../internal.h"
  32
  33/*
  34 * Recalculate the mask of events relevant to a given inode locked.
  35 */
  36static void fsnotify_recalc_inode_mask_locked(struct inode *inode)
  37{
  38        struct fsnotify_mark *mark;
  39        struct hlist_node *pos;
  40        __u32 new_mask = 0;
  41
  42        assert_spin_locked(&inode->i_lock);
  43
  44        hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list)
  45                new_mask |= mark->mask;
  46        inode->i_fsnotify_mask = new_mask;
  47}
  48
  49/*
  50 * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
  51 * any notifier is interested in hearing for this inode.
  52 */
  53void fsnotify_recalc_inode_mask(struct inode *inode)
  54{
  55        spin_lock(&inode->i_lock);
  56        fsnotify_recalc_inode_mask_locked(inode);
  57        spin_unlock(&inode->i_lock);
  58
  59        __fsnotify_update_child_dentry_flags(inode);
  60}
  61
  62void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
  63{
  64        struct inode *inode = mark->i.inode;
  65
  66        assert_spin_locked(&mark->lock);
  67        assert_spin_locked(&mark->group->mark_lock);
  68
  69        spin_lock(&inode->i_lock);
  70
  71        hlist_del_init_rcu(&mark->i.i_list);
  72        mark->i.inode = NULL;
  73
  74        /*
  75         * this mark is now off the inode->i_fsnotify_marks list and we
  76         * hold the inode->i_lock, so this is the perfect time to update the
  77         * inode->i_fsnotify_mask
  78         */
  79        fsnotify_recalc_inode_mask_locked(inode);
  80
  81        spin_unlock(&inode->i_lock);
  82}
  83
  84/*
  85 * Given an inode, destroy all of the marks associated with that inode.
  86 */
  87void fsnotify_clear_marks_by_inode(struct inode *inode)
  88{
  89        struct fsnotify_mark *mark, *lmark;
  90        struct hlist_node *pos, *n;
  91        LIST_HEAD(free_list);
  92
  93        spin_lock(&inode->i_lock);
  94        hlist_for_each_entry_safe(mark, pos, n, &inode->i_fsnotify_marks, i.i_list) {
  95                list_add(&mark->i.free_i_list, &free_list);
  96                hlist_del_init_rcu(&mark->i.i_list);
  97                fsnotify_get_mark(mark);
  98        }
  99        spin_unlock(&inode->i_lock);
 100
 101        list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
 102                fsnotify_destroy_mark(mark);
 103                fsnotify_put_mark(mark);
 104        }
 105}
 106
 107/*
 108 * Given a group clear all of the inode marks associated with that group.
 109 */
 110void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
 111{
 112        fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
 113}
 114
 115/*
 116 * given a group and inode, find the mark associated with that combination.
 117 * if found take a reference to that mark and return it, else return NULL
 118 */
 119struct fsnotify_mark *fsnotify_find_inode_mark_locked(struct fsnotify_group *group,
 120                                                      struct inode *inode)
 121{
 122        struct fsnotify_mark *mark;
 123        struct hlist_node *pos;
 124
 125        assert_spin_locked(&inode->i_lock);
 126
 127        hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list) {
 128                if (mark->group == group) {
 129                        fsnotify_get_mark(mark);
 130                        return mark;
 131                }
 132        }
 133        return NULL;
 134}
 135
 136/*
 137 * given a group and inode, find the mark associated with that combination.
 138 * if found take a reference to that mark and return it, else return NULL
 139 */
 140struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group,
 141                                               struct inode *inode)
 142{
 143        struct fsnotify_mark *mark;
 144
 145        spin_lock(&inode->i_lock);
 146        mark = fsnotify_find_inode_mark_locked(group, inode);
 147        spin_unlock(&inode->i_lock);
 148
 149        return mark;
 150}
 151
 152/*
 153 * If we are setting a mark mask on an inode mark we should pin the inode
 154 * in memory.
 155 */
 156void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
 157                                         __u32 mask)
 158{
 159        struct inode *inode;
 160
 161        assert_spin_locked(&mark->lock);
 162
 163        if (mask &&
 164            mark->i.inode &&
 165            !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
 166                mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
 167                inode = igrab(mark->i.inode);
 168                /*
 169                 * we shouldn't be able to get here if the inode wasn't
 170                 * already safely held in memory.  But bug in case it
 171                 * ever is wrong.
 172                 */
 173                BUG_ON(!inode);
 174        }
 175}
 176
 177/*
 178 * Attach an initialized mark to a given inode.
 179 * These marks may be used for the fsnotify backend to determine which
 180 * event types should be delivered to which group and for which inodes.  These
 181 * marks are ordered according to priority, highest number first, and then by
 182 * the group's location in memory.
 183 */
 184int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
 185                            struct fsnotify_group *group, struct inode *inode,
 186                            int allow_dups)
 187{
 188        struct fsnotify_mark *lmark;
 189        struct hlist_node *node, *last = NULL;
 190        int ret = 0;
 191
 192        mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
 193
 194        assert_spin_locked(&mark->lock);
 195        assert_spin_locked(&group->mark_lock);
 196
 197        spin_lock(&inode->i_lock);
 198
 199        mark->i.inode = inode;
 200
 201        /* is mark the first mark? */
 202        if (hlist_empty(&inode->i_fsnotify_marks)) {
 203                hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
 204                goto out;
 205        }
 206
 207        /* should mark be in the middle of the current list? */
 208        hlist_for_each_entry(lmark, node, &inode->i_fsnotify_marks, i.i_list) {
 209                last = node;
 210
 211                if ((lmark->group == group) && !allow_dups) {
 212                        ret = -EEXIST;
 213                        goto out;
 214                }
 215
 216                if (mark->group->priority < lmark->group->priority)
 217                        continue;
 218
 219                if ((mark->group->priority == lmark->group->priority) &&
 220                    (mark->group < lmark->group))
 221                        continue;
 222
 223                hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
 224                goto out;
 225        }
 226
 227        BUG_ON(last == NULL);
 228        /* mark should be the last entry.  last is the current last entry */
 229        hlist_add_after_rcu(last, &mark->i.i_list);
 230out:
 231        fsnotify_recalc_inode_mask_locked(inode);
 232        spin_unlock(&inode->i_lock);
 233
 234        return ret;
 235}
 236
 237/**
 238 * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
 239 * @list: list of inodes being unmounted (sb->s_inodes)
 240 *
 241 * Called during unmount with no locks held, so needs to be safe against
 242 * concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block.
 243 */
 244void fsnotify_unmount_inodes(struct list_head *list)
 245{
 246        struct inode *inode, *next_i, *need_iput = NULL;
 247
 248        spin_lock(&inode_sb_list_lock);
 249        list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
 250                struct inode *need_iput_tmp;
 251
 252                /*
 253                 * We cannot __iget() an inode in state I_FREEING,
 254                 * I_WILL_FREE, or I_NEW which is fine because by that point
 255                 * the inode cannot have any associated watches.
 256                 */
 257                spin_lock(&inode->i_lock);
 258                if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
 259                        spin_unlock(&inode->i_lock);
 260                        continue;
 261                }
 262
 263                /*
 264                 * If i_count is zero, the inode cannot have any watches and
 265                 * doing an __iget/iput with MS_ACTIVE clear would actually
 266                 * evict all inodes with zero i_count from icache which is
 267                 * unnecessarily violent and may in fact be illegal to do.
 268                 */
 269                if (!atomic_read(&inode->i_count)) {
 270                        spin_unlock(&inode->i_lock);
 271                        continue;
 272                }
 273
 274                need_iput_tmp = need_iput;
 275                need_iput = NULL;
 276
 277                /* In case fsnotify_inode_delete() drops a reference. */
 278                if (inode != need_iput_tmp)
 279                        __iget(inode);
 280                else
 281                        need_iput_tmp = NULL;
 282                spin_unlock(&inode->i_lock);
 283
 284                /* In case the dropping of a reference would nuke next_i. */
 285                if ((&next_i->i_sb_list != list) &&
 286                    atomic_read(&next_i->i_count)) {
 287                        spin_lock(&next_i->i_lock);
 288                        if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
 289                                __iget(next_i);
 290                                need_iput = next_i;
 291                        }
 292                        spin_unlock(&next_i->i_lock);
 293                }
 294
 295                /*
 296                 * We can safely drop inode_sb_list_lock here because we hold
 297                 * references on both inode and next_i.  Also no new inodes
 298                 * will be added since the umount has begun.
 299                 */
 300                spin_unlock(&inode_sb_list_lock);
 301
 302                if (need_iput_tmp)
 303                        iput(need_iput_tmp);
 304
 305                /* for each watch, send FS_UNMOUNT and then remove it */
 306                fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
 307
 308                fsnotify_inode_delete(inode);
 309
 310                iput(inode);
 311
 312                spin_lock(&inode_sb_list_lock);
 313        }
 314        spin_unlock(&inode_sb_list_lock);
 315}
 316
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.