[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/fs/notify/mark.c b/ap/os/linux/linux-3.4.x/fs/notify/mark.c
new file mode 100644
index 0000000..f104d56
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/notify/mark.c
@@ -0,0 +1,372 @@
+/*
+ * 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.
+ */
+
+/*
+ * fsnotify inode mark locking/lifetime/and refcnting
+ *
+ * REFCNT:
+ * The mark->refcnt tells how many "things" in the kernel currently are
+ * referencing this object. The object typically will live inside the kernel
+ * with a refcnt of 2, one for each list it is on (i_list, g_list). Any task
+ * which can find this object holding the appropriete locks, can take a reference
+ * and the object itself is guaranteed to survive until the reference is dropped.
+ *
+ * LOCKING:
+ * There are 3 spinlocks involved with fsnotify inode marks and they MUST
+ * be taken in order as follows:
+ *
+ * mark->lock
+ * group->mark_lock
+ * inode->i_lock
+ *
+ * mark->lock protects 2 things, mark->group and mark->inode. You must hold
+ * that lock to dereference either of these things (they could be NULL even with
+ * the lock)
+ *
+ * group->mark_lock protects the marks_list anchored inside a given group
+ * and each mark is hooked via the g_list. It also sorta protects the
+ * free_g_list, which when used is anchored by a private list on the stack of the
+ * task which held the group->mark_lock.
+ *
+ * inode->i_lock protects the i_fsnotify_marks list anchored inside a
+ * given inode and each mark is hooked via the i_list. (and sorta the
+ * free_i_list)
+ *
+ *
+ * LIFETIME:
+ * Inode marks survive between when they are added to an inode and when their
+ * refcnt==0.
+ *
+ * The inode mark can be cleared for a number of different reasons including:
+ * - The inode is unlinked for the last time. (fsnotify_inode_remove)
+ * - The inode is being evicted from cache. (fsnotify_inode_delete)
+ * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes)
+ * - Something explicitly requests that it be removed. (fsnotify_destroy_mark)
+ * - The fsnotify_group associated with the mark is going away and all such marks
+ * need to be cleaned up. (fsnotify_clear_marks_by_group)
+ *
+ * Worst case we are given an inode and need to clean up all the marks on that
+ * inode. We take i_lock and walk the i_fsnotify_marks safely. For each
+ * mark on the list we take a reference (so the mark can't disappear under us).
+ * We remove that mark form the inode's list of marks and we add this mark to a
+ * private list anchored on the stack using i_free_list; At this point we no
+ * longer fear anything finding the mark using the inode's list of marks.
+ *
+ * We can safely and locklessly run the private list on the stack of everything
+ * we just unattached from the original inode. For each mark on the private list
+ * we grab the mark-> and can thus dereference mark->group and mark->inode. If
+ * we see the group and inode are not NULL we take those locks. Now holding all
+ * 3 locks we can completely remove the mark from other tasks finding it in the
+ * future. Remember, 10 things might already be referencing this mark, but they
+ * better be holding a ref. We drop our reference we took before we unhooked it
+ * from the inode. When the ref hits 0 we can free the mark.
+ *
+ * Very similarly for freeing by group, except we use free_g_list.
+ *
+ * This has the very interesting property of being able to run concurrently with
+ * any (or all) other directions.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/srcu.h>
+
+#include <linux/atomic.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+struct srcu_struct fsnotify_mark_srcu;
+static DEFINE_SPINLOCK(destroy_lock);
+static LIST_HEAD(destroy_list);
+static DECLARE_WAIT_QUEUE_HEAD(destroy_waitq);
+
+void fsnotify_get_mark(struct fsnotify_mark *mark)
+{
+ atomic_inc(&mark->refcnt);
+}
+
+void fsnotify_put_mark(struct fsnotify_mark *mark)
+{
+ if (atomic_dec_and_test(&mark->refcnt))
+ mark->free_mark(mark);
+}
+
+/*
+ * Any time a mark is getting freed we end up here.
+ * The caller had better be holding a reference to this mark so we don't actually
+ * do the final put under the mark->lock
+ */
+void fsnotify_destroy_mark(struct fsnotify_mark *mark)
+{
+ struct fsnotify_group *group;
+ struct inode *inode = NULL;
+
+ spin_lock(&mark->lock);
+
+ group = mark->group;
+
+ /* something else already called this function on this mark */
+ if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) {
+ spin_unlock(&mark->lock);
+ return;
+ }
+
+ mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE;
+
+ spin_lock(&group->mark_lock);
+
+ if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
+ inode = mark->i.inode;
+ fsnotify_destroy_inode_mark(mark);
+ } else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT)
+ fsnotify_destroy_vfsmount_mark(mark);
+ else
+ BUG();
+
+ list_del_init(&mark->g_list);
+
+ spin_unlock(&group->mark_lock);
+ spin_unlock(&mark->lock);
+
+ spin_lock(&destroy_lock);
+ list_add(&mark->destroy_list, &destroy_list);
+ spin_unlock(&destroy_lock);
+ wake_up(&destroy_waitq);
+
+ /*
+ * Some groups like to know that marks are being freed. This is a
+ * callback to the group function to let it know that this mark
+ * is being freed.
+ */
+ if (group->ops->freeing_mark)
+ group->ops->freeing_mark(mark, group);
+
+ /*
+ * __fsnotify_update_child_dentry_flags(inode);
+ *
+ * I really want to call that, but we can't, we have no idea if the inode
+ * still exists the second we drop the mark->lock.
+ *
+ * The next time an event arrive to this inode from one of it's children
+ * __fsnotify_parent will see that the inode doesn't care about it's
+ * children and will update all of these flags then. So really this
+ * is just a lazy update (and could be a perf win...)
+ */
+
+ if (inode && (mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED))
+ iput(inode);
+
+ /*
+ * We don't necessarily have a ref on mark from caller so the above iput
+ * may have already destroyed it. Don't touch from now on.
+ */
+
+ /*
+ * it's possible that this group tried to destroy itself, but this
+ * this mark was simultaneously being freed by inode. If that's the
+ * case, we finish freeing the group here.
+ */
+ if (unlikely(atomic_dec_and_test(&group->num_marks)))
+ fsnotify_final_destroy_group(group);
+}
+
+void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask)
+{
+ assert_spin_locked(&mark->lock);
+
+ mark->mask = mask;
+
+ if (mark->flags & FSNOTIFY_MARK_FLAG_INODE)
+ fsnotify_set_inode_mark_mask_locked(mark, mask);
+}
+
+void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask)
+{
+ assert_spin_locked(&mark->lock);
+
+ mark->ignored_mask = mask;
+}
+
+/*
+ * Attach an initialized mark to a given group and fs object.
+ * These marks may be used for the fsnotify backend to determine which
+ * event types should be delivered to which group.
+ */
+int fsnotify_add_mark(struct fsnotify_mark *mark,
+ struct fsnotify_group *group, struct inode *inode,
+ struct vfsmount *mnt, int allow_dups)
+{
+ int ret = 0;
+
+ BUG_ON(inode && mnt);
+ BUG_ON(!inode && !mnt);
+
+ /*
+ * LOCKING ORDER!!!!
+ * mark->lock
+ * group->mark_lock
+ * inode->i_lock
+ */
+ spin_lock(&mark->lock);
+ spin_lock(&group->mark_lock);
+
+ mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE;
+
+ mark->group = group;
+ list_add(&mark->g_list, &group->marks_list);
+ atomic_inc(&group->num_marks);
+ fsnotify_get_mark(mark); /* for i_list and g_list */
+
+ if (inode) {
+ 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();
+ }
+
+ spin_unlock(&group->mark_lock);
+
+ /* this will pin the object if appropriate */
+ fsnotify_set_mark_mask_locked(mark, mark->mask);
+
+ spin_unlock(&mark->lock);
+
+ if (inode)
+ __fsnotify_update_child_dentry_flags(inode);
+
+ return ret;
+err:
+ mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE;
+ list_del_init(&mark->g_list);
+ mark->group = NULL;
+ atomic_dec(&group->num_marks);
+
+ spin_unlock(&group->mark_lock);
+ spin_unlock(&mark->lock);
+
+ spin_lock(&destroy_lock);
+ list_add(&mark->destroy_list, &destroy_list);
+ spin_unlock(&destroy_lock);
+ wake_up(&destroy_waitq);
+
+ return ret;
+}
+
+/*
+ * clear any marks in a group in which mark->flags & flags is true
+ */
+void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
+ unsigned int flags)
+{
+ struct fsnotify_mark *lmark, *mark;
+ LIST_HEAD(free_list);
+
+ spin_lock(&group->mark_lock);
+ list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
+ if (mark->flags & flags) {
+ list_add(&mark->free_g_list, &free_list);
+ list_del_init(&mark->g_list);
+ fsnotify_get_mark(mark);
+ }
+ }
+ spin_unlock(&group->mark_lock);
+
+ list_for_each_entry_safe(mark, lmark, &free_list, free_g_list) {
+ fsnotify_destroy_mark(mark);
+ fsnotify_put_mark(mark);
+ }
+}
+
+/*
+ * Given a group, destroy all of the marks associated with that group.
+ */
+void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
+{
+ fsnotify_clear_marks_by_group_flags(group, (unsigned int)-1);
+}
+
+void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old)
+{
+ assert_spin_locked(&old->lock);
+ new->i.inode = old->i.inode;
+ new->m.mnt = old->m.mnt;
+ new->group = old->group;
+ new->mask = old->mask;
+ new->free_mark = old->free_mark;
+}
+
+/*
+ * Nothing fancy, just initialize lists and locks and counters.
+ */
+void fsnotify_init_mark(struct fsnotify_mark *mark,
+ void (*free_mark)(struct fsnotify_mark *mark))
+{
+ memset(mark, 0, sizeof(*mark));
+ spin_lock_init(&mark->lock);
+ atomic_set(&mark->refcnt, 1);
+ mark->free_mark = free_mark;
+}
+
+static int fsnotify_mark_destroy(void *ignored)
+{
+ struct fsnotify_mark *mark, *next;
+ LIST_HEAD(private_destroy_list);
+
+ for (;;) {
+ spin_lock(&destroy_lock);
+ /* exchange the list head */
+ list_replace_init(&destroy_list, &private_destroy_list);
+ spin_unlock(&destroy_lock);
+
+ synchronize_srcu(&fsnotify_mark_srcu);
+
+ list_for_each_entry_safe(mark, next, &private_destroy_list, destroy_list) {
+ list_del_init(&mark->destroy_list);
+ fsnotify_put_mark(mark);
+ }
+
+ wait_event_interruptible(destroy_waitq, !list_empty(&destroy_list));
+ }
+
+ return 0;
+}
+
+static int __init fsnotify_mark_init(void)
+{
+ struct task_struct *thread;
+
+ thread = kthread_run(fsnotify_mark_destroy, NULL,
+ "fsnotify_mark");
+ if (IS_ERR(thread))
+ panic("unable to start fsnotify mark destruction thread.");
+
+ return 0;
+}
+device_initcall(fsnotify_mark_init);