vfsmount_mark.c 5.2 KB

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  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. #include <linux/fs.h>
  19. #include <linux/init.h>
  20. #include <linux/kernel.h>
  21. #include <linux/module.h>
  22. #include <linux/mount.h>
  23. #include <linux/mutex.h>
  24. #include <linux/spinlock.h>
  25. #include <linux/atomic.h>
  26. #include <linux/fsnotify_backend.h>
  27. #include "fsnotify.h"
  28. #include "../mount.h"
  29. void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
  30. {
  31. struct fsnotify_mark *mark, *lmark;
  32. struct hlist_node *pos, *n;
  33. struct mount *m = real_mount(mnt);
  34. LIST_HEAD(free_list);
  35. spin_lock(&mnt->mnt_root->d_lock);
  36. hlist_for_each_entry_safe(mark, pos, n, &m->mnt_fsnotify_marks, m.m_list) {
  37. list_add(&mark->m.free_m_list, &free_list);
  38. hlist_del_init_rcu(&mark->m.m_list);
  39. fsnotify_get_mark(mark);
  40. }
  41. spin_unlock(&mnt->mnt_root->d_lock);
  42. list_for_each_entry_safe(mark, lmark, &free_list, m.free_m_list) {
  43. fsnotify_destroy_mark(mark);
  44. fsnotify_put_mark(mark);
  45. }
  46. }
  47. void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
  48. {
  49. fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
  50. }
  51. /*
  52. * Recalculate the mask of events relevant to a given vfsmount locked.
  53. */
  54. static void fsnotify_recalc_vfsmount_mask_locked(struct vfsmount *mnt)
  55. {
  56. struct mount *m = real_mount(mnt);
  57. struct fsnotify_mark *mark;
  58. struct hlist_node *pos;
  59. __u32 new_mask = 0;
  60. assert_spin_locked(&mnt->mnt_root->d_lock);
  61. hlist_for_each_entry(mark, pos, &m->mnt_fsnotify_marks, m.m_list)
  62. new_mask |= mark->mask;
  63. m->mnt_fsnotify_mask = new_mask;
  64. }
  65. /*
  66. * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
  67. * any notifier is interested in hearing for this mount point
  68. */
  69. void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
  70. {
  71. spin_lock(&mnt->mnt_root->d_lock);
  72. fsnotify_recalc_vfsmount_mask_locked(mnt);
  73. spin_unlock(&mnt->mnt_root->d_lock);
  74. }
  75. void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
  76. {
  77. struct vfsmount *mnt = mark->m.mnt;
  78. assert_spin_locked(&mark->lock);
  79. assert_spin_locked(&mark->group->mark_lock);
  80. spin_lock(&mnt->mnt_root->d_lock);
  81. hlist_del_init_rcu(&mark->m.m_list);
  82. mark->m.mnt = NULL;
  83. fsnotify_recalc_vfsmount_mask_locked(mnt);
  84. spin_unlock(&mnt->mnt_root->d_lock);
  85. }
  86. static struct fsnotify_mark *fsnotify_find_vfsmount_mark_locked(struct fsnotify_group *group,
  87. struct vfsmount *mnt)
  88. {
  89. struct mount *m = real_mount(mnt);
  90. struct fsnotify_mark *mark;
  91. struct hlist_node *pos;
  92. assert_spin_locked(&mnt->mnt_root->d_lock);
  93. hlist_for_each_entry(mark, pos, &m->mnt_fsnotify_marks, m.m_list) {
  94. if (mark->group == group) {
  95. fsnotify_get_mark(mark);
  96. return mark;
  97. }
  98. }
  99. return NULL;
  100. }
  101. /*
  102. * given a group and vfsmount, find the mark associated with that combination.
  103. * if found take a reference to that mark and return it, else return NULL
  104. */
  105. struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
  106. struct vfsmount *mnt)
  107. {
  108. struct fsnotify_mark *mark;
  109. spin_lock(&mnt->mnt_root->d_lock);
  110. mark = fsnotify_find_vfsmount_mark_locked(group, mnt);
  111. spin_unlock(&mnt->mnt_root->d_lock);
  112. return mark;
  113. }
  114. /*
  115. * Attach an initialized mark to a given group and vfsmount.
  116. * These marks may be used for the fsnotify backend to determine which
  117. * event types should be delivered to which groups.
  118. */
  119. int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
  120. struct fsnotify_group *group, struct vfsmount *mnt,
  121. int allow_dups)
  122. {
  123. struct mount *m = real_mount(mnt);
  124. struct fsnotify_mark *lmark;
  125. struct hlist_node *node, *last = NULL;
  126. int ret = 0;
  127. mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
  128. assert_spin_locked(&mark->lock);
  129. assert_spin_locked(&group->mark_lock);
  130. spin_lock(&mnt->mnt_root->d_lock);
  131. mark->m.mnt = mnt;
  132. /* is mark the first mark? */
  133. if (hlist_empty(&m->mnt_fsnotify_marks)) {
  134. hlist_add_head_rcu(&mark->m.m_list, &m->mnt_fsnotify_marks);
  135. goto out;
  136. }
  137. /* should mark be in the middle of the current list? */
  138. hlist_for_each_entry(lmark, node, &m->mnt_fsnotify_marks, m.m_list) {
  139. last = node;
  140. if ((lmark->group == group) && !allow_dups) {
  141. ret = -EEXIST;
  142. goto out;
  143. }
  144. if (mark->group->priority < lmark->group->priority)
  145. continue;
  146. if ((mark->group->priority == lmark->group->priority) &&
  147. (mark->group < lmark->group))
  148. continue;
  149. hlist_add_before_rcu(&mark->m.m_list, &lmark->m.m_list);
  150. goto out;
  151. }
  152. BUG_ON(last == NULL);
  153. /* mark should be the last entry. last is the current last entry */
  154. hlist_add_after_rcu(last, &mark->m.m_list);
  155. out:
  156. fsnotify_recalc_vfsmount_mask_locked(mnt);
  157. spin_unlock(&mnt->mnt_root->d_lock);
  158. return ret;
  159. }