fsnotify: vfsmount marks generic functions

Much like inode-mark.c has all of the code dealing with marks on inodes
this patch adds a vfsmount-mark.c which has similar code but is intended
for marks on vfsmounts.

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 171 insertions, 0 deletions

diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c
new file mode 100644
index 000000000000..1b61d0a942de
--- /dev/null
+++ b/fs/notify/vfsmount_mark.c
@@ -0,0 +1,171 @@
+/*
+ *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/writeback.h> /* for inode_lock */
+
+#include <asm/atomic.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
+{
+        struct fsnotify_mark *mark, *lmark;
+        struct hlist_node *pos, *n;
+        LIST_HEAD(free_list);
+
+        spin_lock(&mnt->mnt_root->d_lock);
+        hlist_for_each_entry_safe(mark, pos, n, &mnt->mnt_fsnotify_marks, m.m_list) {
+                list_add(&mark->m.free_m_list, &free_list);
+                hlist_del_init(&mark->m.m_list);
+                fsnotify_get_mark(mark);
+        }
+        spin_unlock(&mnt->mnt_root->d_lock);
+
+        list_for_each_entry_safe(mark, lmark, &free_list, m.free_m_list) {
+                fsnotify_destroy_mark(mark);
+                fsnotify_put_mark(mark);
+        }
+}
+
+/*
+ * Recalculate the mask of events relevant to a given vfsmount locked.
+ */
+static void fsnotify_recalc_vfsmount_mask_locked(struct vfsmount *mnt)
+{
+        struct fsnotify_mark *mark;
+        struct hlist_node *pos;
+        __u32 new_mask = 0;
+
+        assert_spin_locked(&mnt->mnt_root->d_lock);
+
+        hlist_for_each_entry(mark, pos, &mnt->mnt_fsnotify_marks, m.m_list)
+                new_mask |= mark->mask;
+        mnt->mnt_fsnotify_mask = new_mask;
+}
+
+/*
+ * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
+ * any notifier is interested in hearing for this mount point
+ */
+void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
+{
+        spin_lock(&mnt->mnt_root->d_lock);
+        fsnotify_recalc_vfsmount_mask_locked(mnt);
+        spin_unlock(&mnt->mnt_root->d_lock);
+}
+
+void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
+{
+        struct vfsmount *mnt = mark->m.mnt;
+
+        assert_spin_locked(&mark->lock);
+        assert_spin_locked(&mark->group->mark_lock);
+
+        spin_lock(&mnt->mnt_root->d_lock);
+
+        hlist_del_init(&mark->m.m_list);
+        mark->m.mnt = NULL;
+
+        fsnotify_recalc_vfsmount_mask_locked(mnt);
+
+        spin_unlock(&mnt->mnt_root->d_lock);
+}
+
+static struct fsnotify_mark *fsnotify_find_vfsmount_mark_locked(struct fsnotify_group *group,
+                                                                struct vfsmount *mnt)
+{
+        struct fsnotify_mark *mark;
+        struct hlist_node *pos;
+
+        assert_spin_locked(&mnt->mnt_root->d_lock);
+
+        hlist_for_each_entry(mark, pos, &mnt->mnt_fsnotify_marks, m.m_list) {
+                if (mark->group == group) {
+                        fsnotify_get_mark(mark);
+                        return mark;
+                }
+        }
+        return NULL;
+}
+
+/*
+ * given a group and vfsmount, find the mark associated with that combination.
+ * if found take a reference to that mark and return it, else return NULL
+ */
+struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
+                                                  struct vfsmount *mnt)
+{
+        struct fsnotify_mark *mark;
+
+        spin_lock(&mnt->mnt_root->d_lock);
+        mark = fsnotify_find_vfsmount_mark_locked(group, mnt);
+        spin_unlock(&mnt->mnt_root->d_lock);
+
+        return mark;
+}
+
+/*
+ * Attach an initialized mark to a given group and vfsmount.
+ * These marks may be used for the fsnotify backend to determine which
+ * event types should be delivered to which groups.
+ */
+int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
+                               struct fsnotify_group *group, struct vfsmount *mnt,
+                               int allow_dups)
+{
+        struct fsnotify_mark *lmark = NULL;
+        int ret = 0;
+
+        mark->flags = FSNOTIFY_MARK_FLAG_VFSMOUNT;
+
+        /*
+         * LOCKING ORDER!!!!
+         * mark->lock
+         * group->mark_lock
+         * mnt->mnt_root->d_lock
+         */
+        assert_spin_locked(&mark->lock);
+        assert_spin_locked(&group->mark_lock);
+
+        spin_lock(&mnt->mnt_root->d_lock);
+
+        if (!allow_dups)
+                lmark = fsnotify_find_vfsmount_mark_locked(group, mnt);
+        if (!lmark) {
+                mark->m.mnt = mnt;
+
+                hlist_add_head(&mark->m.m_list, &mnt->mnt_fsnotify_marks);
+
+                fsnotify_recalc_vfsmount_mask_locked(mnt);
+        } else {
+                ret = -EEXIST;
+        }
+
+        spin_unlock(&mnt->mnt_root->d_lock);
+
+        return ret;
+}