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>

4 files changed, 189 insertions, 10 deletions

diff --git a/fs/notify/Makefile b/fs/notify/Makefile
index 8f7f3b024a2e..ae5f33a6d868 100644
--- a/fs/notify/Makefile
+++ b/fs/notify/Makefile
@@ -1,5 +1,5 @@
 obj-$(CONFIG_FSNOTIFY)          += fsnotify.o notification.o group.o inode_mark.o \
-                                   mark.o
+                                   mark.o vfsmount_mark.o
 
 obj-y                   += dnotify/
 obj-y                   += inotify/
diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index 7c7a904b802d..38f3fb5cef28 100644
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -24,6 +24,10 @@ extern void fsnotify_flush_notify(struct fsnotify_group *group);
 extern int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
                                    struct fsnotify_group *group, struct inode *inode,
                                    int allow_dups);
+/* add a mark to a vfsmount */
+extern int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
+                                      struct fsnotify_group *group, struct vfsmount *mnt,
+                                      int allow_dups);
 
 /* add a group to the inode group list */
 extern void fsnotify_add_inode_group(struct fsnotify_group *group);
@@ -32,6 +36,8 @@ extern void fsnotify_add_vfsmount_group(struct fsnotify_group *group);
 /* final kfree of a group */
 extern void fsnotify_final_destroy_group(struct fsnotify_group *group);
 
+/* vfsmount specific destruction of a mark */
+extern void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark);
 /* inode specific destruction of a mark */
 extern void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark);
 /* run the list of all marks associated with inode and flag them to be freed */
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 57bb1d74a2b6..d296ec9ffb2a 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -115,15 +115,11 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
 void fsnotify_destroy_mark(struct fsnotify_mark *mark)
 {
         struct fsnotify_group *group;
-        struct inode *inode;
+        struct inode *inode = NULL;
 
         spin_lock(&mark->lock);
 
         group = mark->group;
-        inode = mark->i.inode;
-
-        BUG_ON(group && !inode);
-        BUG_ON(!group && inode);
 
         /* if !group something else already marked this to die */
         if (!group) {
@@ -136,8 +132,11 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
 
         spin_lock(&group->mark_lock);
 
-        if (mark->flags & FSNOTIFY_MARK_FLAG_INODE)
+        if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
                 fsnotify_destroy_inode_mark(mark);
+                inode = mark->i.inode;
+        } else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT)
+                fsnotify_destroy_vfsmount_mark(mark);
         else
                 BUG();
 
@@ -169,8 +168,8 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
          * is just a lazy update (and could be a perf win...)
          */
 
-
-        iput(inode);
+        if (inode)
+                iput(inode);
 
         /*
          * it's possible that this group tried to destroy itself, but this
@@ -192,7 +191,6 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
 {
         int ret = 0;
 
-        BUG_ON(mnt);
         BUG_ON(inode && mnt);
         BUG_ON(!inode && !mnt);
 
@@ -223,6 +221,10 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
                 ret = fsnotify_add_inode_mark(mark, group, inode, allow_dups);
                 if (ret)
                         goto err;
+        } else if (mnt) {
+                ret = fsnotify_add_vfsmount_mark(mark, group, mnt, allow_dups);
+                if (ret)
+                        goto err;
         } else {
                 BUG();
         }
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;
+}