1 files changed, 407 insertions, 0 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
new file mode 100644
index 000000000..e8ee4263d
--- /dev/null
+++ b/fs/notify/fsnotify.c
@@ -0,0 +1,407 @@
+/*
+ *  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/dcache.h>
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/srcu.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+/*
+ * Clear all of the marks on an inode when it is being evicted from core
+ */
+void __fsnotify_inode_delete(struct inode *inode)
+{
+	fsnotify_clear_marks_by_inode(inode);
+}
+EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
+
+void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
+{
+	fsnotify_clear_marks_by_mount(mnt);
+}
+
+/**
+ * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
+ * @sb: superblock being unmounted.
+ *
+ * Called during unmount with no locks held, so needs to be safe against
+ * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
+ */
+void fsnotify_unmount_inodes(struct super_block *sb)
+{
+	struct inode *inode, *iput_inode = NULL;
+
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		/*
+		 * We cannot __iget() an inode in state I_FREEING,
+		 * I_WILL_FREE, or I_NEW which is fine because by that point
+		 * the inode cannot have any associated watches.
+		 */
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		/*
+		 * If i_count is zero, the inode cannot have any watches and
+		 * doing an __iget/iput with SB_ACTIVE clear would actually
+		 * evict all inodes with zero i_count from icache which is
+		 * unnecessarily violent and may in fact be illegal to do.
+		 */
+		if (!atomic_read(&inode->i_count)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&sb->s_inode_list_lock);
+
+		if (iput_inode)
+			iput(iput_inode);
+
+		/* for each watch, send FS_UNMOUNT and then remove it */
+		fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+
+		fsnotify_inode_delete(inode);
+
+		iput_inode = inode;
+
+		cond_resched();
+		spin_lock(&sb->s_inode_list_lock);
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+
+	if (iput_inode)
+		iput(iput_inode);
+	/* Wait for outstanding inode references from connectors */
+	wait_var_event(&sb->s_fsnotify_inode_refs,
+		       !atomic_long_read(&sb->s_fsnotify_inode_refs));
+}
+
+/*
+ * Given an inode, first check if we care what happens to our children.  Inotify
+ * and dnotify both tell their parents about events.  If we care about any event
+ * on a child we run all of our children and set a dentry flag saying that the
+ * parent cares.  Thus when an event happens on a child it can quickly tell if
+ * if there is a need to find a parent and send the event to the parent.
+ */
+void __fsnotify_update_child_dentry_flags(struct inode *inode)
+{
+	struct dentry *alias;
+	int watched;
+
+	if (!S_ISDIR(inode->i_mode))
+		return;
+
+	/* determine if the children should tell inode about their events */
+	watched = fsnotify_inode_watches_children(inode);
+
+	spin_lock(&inode->i_lock);
+	/* run all of the dentries associated with this inode.  Since this is a
+	 * directory, there damn well better only be one item on this list */
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
+		struct dentry *child;
+
+		/* run all of the children of the original inode and fix their
+		 * d_flags to indicate parental interest (their parent is the
+		 * original inode) */
+		spin_lock(&alias->d_lock);
+		list_for_each_entry(child, &alias->d_subdirs, d_child) {
+			if (!child->d_inode)
+				continue;
+
+			spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
+			if (watched)
+				child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+			else
+				child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+			spin_unlock(&child->d_lock);
+		}
+		spin_unlock(&alias->d_lock);
+	}
+	spin_unlock(&inode->i_lock);
+}
+
+/* Notify this dentry's parent about a child's events. */
+int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
+{
+	struct dentry *parent;
+	struct inode *p_inode;
+	int ret = 0;
+
+	if (!dentry)
+		dentry = path->dentry;
+
+	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
+		return 0;
+
+	parent = dget_parent(dentry);
+	p_inode = parent->d_inode;
+
+	if (unlikely(!fsnotify_inode_watches_children(p_inode))) {
+		__fsnotify_update_child_dentry_flags(p_inode);
+	} else if (p_inode->i_fsnotify_mask & mask & ALL_FSNOTIFY_EVENTS) {
+		struct name_snapshot name;
+
+		/* we are notifying a parent so come up with the new mask which
+		 * specifies these are events which came from a child. */
+		mask |= FS_EVENT_ON_CHILD;
+
+		take_dentry_name_snapshot(&name, dentry);
+		if (path)
+			ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
+				       name.name, 0);
+		else
+			ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
+				       name.name, 0);
+		release_dentry_name_snapshot(&name);
+	}
+
+	dput(parent);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__fsnotify_parent);
+
+static int send_to_group(struct inode *to_tell,
+			 __u32 mask, const void *data,
+			 int data_is, u32 cookie,
+			 const unsigned char *file_name,
+			 struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_group *group = NULL;
+	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
+	__u32 marks_mask = 0;
+	__u32 marks_ignored_mask = 0;
+	struct fsnotify_mark *mark;
+	int type;
+
+	if (WARN_ON(!iter_info->report_mask))
+		return 0;
+
+	/* clear ignored on inode modification */
+	if (mask & FS_MODIFY) {
+		fsnotify_foreach_obj_type(type) {
+			if (!fsnotify_iter_should_report_type(iter_info, type))
+				continue;
+			mark = iter_info->marks[type];
+			if (mark &&
+			    !(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
+				mark->ignored_mask = 0;
+		}
+	}
+
+	fsnotify_foreach_obj_type(type) {
+		if (!fsnotify_iter_should_report_type(iter_info, type))
+			continue;
+		mark = iter_info->marks[type];
+		/* does the object mark tell us to do something? */
+		if (mark) {
+			group = mark->group;
+			marks_mask |= mark->mask;
+			marks_ignored_mask |= mark->ignored_mask;
+		}
+	}
+
+	pr_debug("%s: group=%p to_tell=%p mask=%x marks_mask=%x marks_ignored_mask=%x"
+		 " data=%p data_is=%d cookie=%d\n",
+		 __func__, group, to_tell, mask, marks_mask, marks_ignored_mask,
+		 data, data_is, cookie);
+
+	if (!(test_mask & marks_mask & ~marks_ignored_mask))
+		return 0;
+
+	return group->ops->handle_event(group, to_tell, mask, data, data_is,
+					file_name, cookie, iter_info);
+}
+
+static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
+{
+	struct fsnotify_mark_connector *conn;
+	struct hlist_node *node = NULL;
+
+	conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
+	if (conn)
+		node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu);
+
+	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
+static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
+{
+	struct hlist_node *node = NULL;
+
+	if (mark)
+		node = srcu_dereference(mark->obj_list.next,
+					&fsnotify_mark_srcu);
+
+	return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
+}
+
+/*
+ * iter_info is a multi head priority queue of marks.
+ * Pick a subset of marks from queue heads, all with the
+ * same group and set the report_mask for selected subset.
+ * Returns the report_mask of the selected subset.
+ */
+static unsigned int fsnotify_iter_select_report_types(
+		struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_group *max_prio_group = NULL;
+	struct fsnotify_mark *mark;
+	int type;
+
+	/* Choose max prio group among groups of all queue heads */
+	fsnotify_foreach_obj_type(type) {
+		mark = iter_info->marks[type];
+		if (mark &&
+		    fsnotify_compare_groups(max_prio_group, mark->group) > 0)
+			max_prio_group = mark->group;
+	}
+
+	if (!max_prio_group)
+		return 0;
+
+	/* Set the report mask for marks from same group as max prio group */
+	iter_info->report_mask = 0;
+	fsnotify_foreach_obj_type(type) {
+		mark = iter_info->marks[type];
+		if (mark &&
+		    fsnotify_compare_groups(max_prio_group, mark->group) == 0)
+			fsnotify_iter_set_report_type(iter_info, type);
+	}
+
+	return iter_info->report_mask;
+}
+
+/*
+ * Pop from iter_info multi head queue, the marks that were iterated in the
+ * current iteration step.
+ */
+static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
+{
+	int type;
+
+	fsnotify_foreach_obj_type(type) {
+		if (fsnotify_iter_should_report_type(iter_info, type))
+			iter_info->marks[type] =
+				fsnotify_next_mark(iter_info->marks[type]);
+	}
+}
+
+/*
+ * This is the main call to fsnotify.  The VFS calls into hook specific functions
+ * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
+ * out to all of the registered fsnotify_group.  Those groups can then use the
+ * notification event in whatever means they feel necessary.
+ */
+int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
+	     const unsigned char *file_name, u32 cookie)
+{
+	struct fsnotify_iter_info iter_info = {};
+	struct mount *mnt;
+	int ret = 0;
+	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
+
+	if (data_is == FSNOTIFY_EVENT_PATH)
+		mnt = real_mount(((const struct path *)data)->mnt);
+	else
+		mnt = NULL;
+
+	/* An event "on child" is not intended for a mount mark */
+	if (mask & FS_EVENT_ON_CHILD)
+		mnt = NULL;
+
+	/*
+	 * Optimization: srcu_read_lock() has a memory barrier which can
+	 * be expensive.  It protects walking the *_fsnotify_marks lists.
+	 * However, if we do not walk the lists, we do not have to do
+	 * SRCU because we have no references to any objects and do not
+	 * need SRCU to keep them "alive".
+	 */
+	if (!to_tell->i_fsnotify_marks &&
+	    (!mnt || !mnt->mnt_fsnotify_marks))
+		return 0;
+	/*
+	 * if this is a modify event we may need to clear the ignored masks
+	 * otherwise return if neither the inode nor the vfsmount care about
+	 * this type of event.
+	 */
+	if (!(mask & FS_MODIFY) &&
+	    !(test_mask & to_tell->i_fsnotify_mask) &&
+	    !(mnt && test_mask & mnt->mnt_fsnotify_mask))
+		return 0;
+
+	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
+
+	iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] =
+		fsnotify_first_mark(&to_tell->i_fsnotify_marks);
+	if (mnt) {
+		iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] =
+			fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
+	}
+
+	/*
+	 * We need to merge inode & vfsmount mark lists so that inode mark
+	 * ignore masks are properly reflected for mount mark notifications.
+	 * That's why this traversal is so complicated...
+	 */
+	while (fsnotify_iter_select_report_types(&iter_info)) {
+		ret = send_to_group(to_tell, mask, data, data_is, cookie,
+				    file_name, &iter_info);
+
+		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
+			goto out;
+
+		fsnotify_iter_next(&iter_info);
+	}
+	ret = 0;
+out:
+	srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(fsnotify);
+
+extern struct kmem_cache *fsnotify_mark_connector_cachep;
+
+static __init int fsnotify_init(void)
+{
+	int ret;
+
+	BUG_ON(hweight32(ALL_FSNOTIFY_BITS) != 23);
+
+	ret = init_srcu_struct(&fsnotify_mark_srcu);
+	if (ret)
+		panic("initializing fsnotify_mark_srcu");
+
+	fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector,
+						    SLAB_PANIC);
+
+	return 0;
+}
+core_initcall(fsnotify_init);