![Amir Goldstein](/assets/img/avatar_default.png)
Use fsnotify_foreach_obj_type macros to generalize the code that filters events by marks mask and ignored_mask. This is going to be used for adding mark of super block object type. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
408 lines
12 KiB
C
408 lines
12 KiB
C
/*
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/dcache.h>
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#include <linux/fs.h>
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#include <linux/gfp.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mount.h>
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#include <linux/srcu.h>
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#include <linux/fsnotify_backend.h>
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#include "fsnotify.h"
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/*
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* Clear all of the marks on an inode when it is being evicted from core
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*/
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void __fsnotify_inode_delete(struct inode *inode)
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{
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fsnotify_clear_marks_by_inode(inode);
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}
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EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
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void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
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{
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fsnotify_clear_marks_by_mount(mnt);
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}
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/**
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* fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
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* @sb: superblock being unmounted.
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*
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* Called during unmount with no locks held, so needs to be safe against
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* concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
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*/
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void fsnotify_unmount_inodes(struct super_block *sb)
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{
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struct inode *inode, *iput_inode = NULL;
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spin_lock(&sb->s_inode_list_lock);
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list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
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/*
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* We cannot __iget() an inode in state I_FREEING,
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* I_WILL_FREE, or I_NEW which is fine because by that point
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* the inode cannot have any associated watches.
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*/
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spin_lock(&inode->i_lock);
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if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
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spin_unlock(&inode->i_lock);
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continue;
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}
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/*
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* If i_count is zero, the inode cannot have any watches and
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* doing an __iget/iput with SB_ACTIVE clear would actually
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* evict all inodes with zero i_count from icache which is
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* unnecessarily violent and may in fact be illegal to do.
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*/
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if (!atomic_read(&inode->i_count)) {
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spin_unlock(&inode->i_lock);
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continue;
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}
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__iget(inode);
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spin_unlock(&inode->i_lock);
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spin_unlock(&sb->s_inode_list_lock);
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if (iput_inode)
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iput(iput_inode);
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/* for each watch, send FS_UNMOUNT and then remove it */
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fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
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fsnotify_inode_delete(inode);
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iput_inode = inode;
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spin_lock(&sb->s_inode_list_lock);
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}
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spin_unlock(&sb->s_inode_list_lock);
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if (iput_inode)
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iput(iput_inode);
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}
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/*
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* Given an inode, first check if we care what happens to our children. Inotify
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* and dnotify both tell their parents about events. If we care about any event
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* on a child we run all of our children and set a dentry flag saying that the
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* parent cares. Thus when an event happens on a child it can quickly tell if
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* if there is a need to find a parent and send the event to the parent.
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*/
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void __fsnotify_update_child_dentry_flags(struct inode *inode)
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{
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struct dentry *alias;
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int watched;
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if (!S_ISDIR(inode->i_mode))
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return;
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/* determine if the children should tell inode about their events */
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watched = fsnotify_inode_watches_children(inode);
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spin_lock(&inode->i_lock);
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/* run all of the dentries associated with this inode. Since this is a
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* directory, there damn well better only be one item on this list */
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hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
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struct dentry *child;
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/* run all of the children of the original inode and fix their
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* d_flags to indicate parental interest (their parent is the
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* original inode) */
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spin_lock(&alias->d_lock);
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list_for_each_entry(child, &alias->d_subdirs, d_child) {
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if (!child->d_inode)
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continue;
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spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
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if (watched)
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child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
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else
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child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
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spin_unlock(&child->d_lock);
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}
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spin_unlock(&alias->d_lock);
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}
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spin_unlock(&inode->i_lock);
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}
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/* Notify this dentry's parent about a child's events. */
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int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
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{
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struct dentry *parent;
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struct inode *p_inode;
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int ret = 0;
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if (!dentry)
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dentry = path->dentry;
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if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
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return 0;
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parent = dget_parent(dentry);
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p_inode = parent->d_inode;
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if (unlikely(!fsnotify_inode_watches_children(p_inode)))
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__fsnotify_update_child_dentry_flags(p_inode);
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else if (p_inode->i_fsnotify_mask & mask) {
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struct name_snapshot name;
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/* we are notifying a parent so come up with the new mask which
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* specifies these are events which came from a child. */
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mask |= FS_EVENT_ON_CHILD;
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take_dentry_name_snapshot(&name, dentry);
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if (path)
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ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
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name.name, 0);
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else
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ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
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name.name, 0);
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release_dentry_name_snapshot(&name);
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}
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dput(parent);
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return ret;
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}
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EXPORT_SYMBOL_GPL(__fsnotify_parent);
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static int send_to_group(struct inode *to_tell,
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__u32 mask, const void *data,
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int data_is, u32 cookie,
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const unsigned char *file_name,
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struct fsnotify_iter_info *iter_info)
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{
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struct fsnotify_group *group = NULL;
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__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
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__u32 marks_mask = 0;
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__u32 marks_ignored_mask = 0;
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struct fsnotify_mark *mark;
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int type;
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if (WARN_ON(!iter_info->report_mask))
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return 0;
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/* clear ignored on inode modification */
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if (mask & FS_MODIFY) {
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fsnotify_foreach_obj_type(type) {
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if (!fsnotify_iter_should_report_type(iter_info, type))
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continue;
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mark = iter_info->marks[type];
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if (mark &&
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!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
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mark->ignored_mask = 0;
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}
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}
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fsnotify_foreach_obj_type(type) {
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if (!fsnotify_iter_should_report_type(iter_info, type))
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continue;
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mark = iter_info->marks[type];
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/* does the object mark tell us to do something? */
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if (mark) {
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group = mark->group;
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marks_mask |= mark->mask;
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marks_ignored_mask |= mark->ignored_mask;
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}
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}
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pr_debug("%s: group=%p to_tell=%p mask=%x marks_mask=%x marks_ignored_mask=%x"
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" data=%p data_is=%d cookie=%d\n",
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__func__, group, to_tell, mask, marks_mask, marks_ignored_mask,
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data, data_is, cookie);
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if (!(test_mask & marks_mask & ~marks_ignored_mask))
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return 0;
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return group->ops->handle_event(group, to_tell, mask, data, data_is,
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file_name, cookie, iter_info);
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}
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static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
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{
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struct fsnotify_mark_connector *conn;
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struct hlist_node *node = NULL;
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conn = srcu_dereference(*connp, &fsnotify_mark_srcu);
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if (conn)
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node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu);
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return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
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}
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static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
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{
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struct hlist_node *node = NULL;
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if (mark)
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node = srcu_dereference(mark->obj_list.next,
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&fsnotify_mark_srcu);
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return hlist_entry_safe(node, struct fsnotify_mark, obj_list);
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}
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/*
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* iter_info is a multi head priority queue of marks.
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* Pick a subset of marks from queue heads, all with the
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* same group and set the report_mask for selected subset.
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* Returns the report_mask of the selected subset.
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*/
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static unsigned int fsnotify_iter_select_report_types(
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struct fsnotify_iter_info *iter_info)
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{
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struct fsnotify_group *max_prio_group = NULL;
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struct fsnotify_mark *mark;
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int type;
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/* Choose max prio group among groups of all queue heads */
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fsnotify_foreach_obj_type(type) {
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mark = iter_info->marks[type];
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if (mark &&
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fsnotify_compare_groups(max_prio_group, mark->group) > 0)
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max_prio_group = mark->group;
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}
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if (!max_prio_group)
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return 0;
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/* Set the report mask for marks from same group as max prio group */
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iter_info->report_mask = 0;
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fsnotify_foreach_obj_type(type) {
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mark = iter_info->marks[type];
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if (mark &&
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fsnotify_compare_groups(max_prio_group, mark->group) == 0)
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fsnotify_iter_set_report_type(iter_info, type);
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}
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return iter_info->report_mask;
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}
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/*
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* Pop from iter_info multi head queue, the marks that were iterated in the
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* current iteration step.
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*/
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static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
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{
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int type;
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fsnotify_foreach_obj_type(type) {
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if (fsnotify_iter_should_report_type(iter_info, type))
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iter_info->marks[type] =
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fsnotify_next_mark(iter_info->marks[type]);
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}
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}
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/*
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* This is the main call to fsnotify. The VFS calls into hook specific functions
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* in linux/fsnotify.h. Those functions then in turn call here. Here will call
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* out to all of the registered fsnotify_group. Those groups can then use the
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* notification event in whatever means they feel necessary.
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*/
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int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
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const unsigned char *file_name, u32 cookie)
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{
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struct fsnotify_iter_info iter_info = {};
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struct mount *mnt;
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int ret = 0;
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/* global tests shouldn't care about events on child only the specific event */
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__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
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if (data_is == FSNOTIFY_EVENT_PATH)
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mnt = real_mount(((const struct path *)data)->mnt);
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else
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mnt = NULL;
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/*
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* Optimization: srcu_read_lock() has a memory barrier which can
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* be expensive. It protects walking the *_fsnotify_marks lists.
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* However, if we do not walk the lists, we do not have to do
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* SRCU because we have no references to any objects and do not
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* need SRCU to keep them "alive".
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*/
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if (!to_tell->i_fsnotify_marks &&
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(!mnt || !mnt->mnt_fsnotify_marks))
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return 0;
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/*
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* if this is a modify event we may need to clear the ignored masks
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* otherwise return if neither the inode nor the vfsmount care about
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* this type of event.
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*/
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if (!(mask & FS_MODIFY) &&
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!(test_mask & to_tell->i_fsnotify_mask) &&
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!(mnt && test_mask & mnt->mnt_fsnotify_mask))
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return 0;
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iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
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if ((mask & FS_MODIFY) ||
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(test_mask & to_tell->i_fsnotify_mask)) {
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iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] =
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fsnotify_first_mark(&to_tell->i_fsnotify_marks);
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}
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if (mnt && ((mask & FS_MODIFY) ||
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(test_mask & mnt->mnt_fsnotify_mask))) {
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iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] =
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fsnotify_first_mark(&to_tell->i_fsnotify_marks);
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iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] =
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fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
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}
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/*
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* We need to merge inode & vfsmount mark lists so that inode mark
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* ignore masks are properly reflected for mount mark notifications.
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* That's why this traversal is so complicated...
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*/
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while (fsnotify_iter_select_report_types(&iter_info)) {
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ret = send_to_group(to_tell, mask, data, data_is, cookie,
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file_name, &iter_info);
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if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
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goto out;
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fsnotify_iter_next(&iter_info);
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}
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ret = 0;
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out:
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srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx);
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return ret;
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}
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EXPORT_SYMBOL_GPL(fsnotify);
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extern struct kmem_cache *fsnotify_mark_connector_cachep;
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static __init int fsnotify_init(void)
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{
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int ret;
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BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
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ret = init_srcu_struct(&fsnotify_mark_srcu);
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if (ret)
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panic("initializing fsnotify_mark_srcu");
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fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector,
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SLAB_PANIC);
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return 0;
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}
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core_initcall(fsnotify_init);
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