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![Nick Piggin](/assets/img/avatar_default.png)
dcache_inode_lock can be replaced with per-inode locking. Use existing inode->i_lock for this. This is slightly non-trivial because we sometimes need to find the inode from the dentry, which requires d_inode to be stabilised (either with refcount or d_lock). Signed-off-by: Nick Piggin <npiggin@kernel.dk>
310 lines
9.3 KiB
C
310 lines
9.3 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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* 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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list_for_each_entry(alias, &inode->i_dentry, 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_u.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(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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/* 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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if (path)
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ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
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dentry->d_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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dentry->d_name.name, 0);
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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, struct vfsmount *mnt,
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struct fsnotify_mark *inode_mark,
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struct fsnotify_mark *vfsmount_mark,
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__u32 mask, 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_event **event)
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{
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struct fsnotify_group *group = NULL;
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__u32 inode_test_mask = 0;
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__u32 vfsmount_test_mask = 0;
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if (unlikely(!inode_mark && !vfsmount_mark)) {
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BUG();
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return 0;
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}
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/* clear ignored on inode modification */
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if (mask & FS_MODIFY) {
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if (inode_mark &&
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!(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
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inode_mark->ignored_mask = 0;
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if (vfsmount_mark &&
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!(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
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vfsmount_mark->ignored_mask = 0;
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}
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/* does the inode mark tell us to do something? */
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if (inode_mark) {
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group = inode_mark->group;
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inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
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inode_test_mask &= inode_mark->mask;
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inode_test_mask &= ~inode_mark->ignored_mask;
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}
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/* does the vfsmount_mark tell us to do something? */
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if (vfsmount_mark) {
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vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
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group = vfsmount_mark->group;
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vfsmount_test_mask &= vfsmount_mark->mask;
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vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
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if (inode_mark)
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vfsmount_test_mask &= ~inode_mark->ignored_mask;
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}
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pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p"
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" inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
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" data=%p data_is=%d cookie=%d event=%p\n",
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__func__, group, to_tell, mnt, mask, inode_mark,
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inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
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data_is, cookie, *event);
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if (!inode_test_mask && !vfsmount_test_mask)
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return 0;
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if (group->ops->should_send_event(group, to_tell, inode_mark,
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vfsmount_mark, mask, data,
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data_is) == false)
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return 0;
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if (!*event) {
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*event = fsnotify_create_event(to_tell, mask, data,
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data_is, file_name,
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cookie, GFP_KERNEL);
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if (!*event)
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return -ENOMEM;
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}
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return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event);
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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, 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 hlist_node *inode_node = NULL, *vfsmount_node = NULL;
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struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
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struct fsnotify_group *inode_group, *vfsmount_group;
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struct fsnotify_event *event = NULL;
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struct vfsmount *mnt;
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int idx, 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 = ((struct path *)data)->mnt;
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else
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mnt = NULL;
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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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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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inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
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&fsnotify_mark_srcu);
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if (mnt && ((mask & FS_MODIFY) ||
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(test_mask & mnt->mnt_fsnotify_mask))) {
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vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
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&fsnotify_mark_srcu);
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inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
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&fsnotify_mark_srcu);
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}
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while (inode_node || vfsmount_node) {
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inode_group = vfsmount_group = NULL;
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if (inode_node) {
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inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
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struct fsnotify_mark, i.i_list);
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inode_group = inode_mark->group;
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}
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if (vfsmount_node) {
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vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
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struct fsnotify_mark, m.m_list);
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vfsmount_group = vfsmount_mark->group;
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}
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if (inode_group > vfsmount_group) {
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/* handle inode */
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ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
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data_is, cookie, file_name, &event);
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/* we didn't use the vfsmount_mark */
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vfsmount_group = NULL;
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} else if (vfsmount_group > inode_group) {
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ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
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data_is, cookie, file_name, &event);
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inode_group = NULL;
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} else {
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ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
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mask, data, data_is, cookie, file_name,
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&event);
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}
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if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
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goto out;
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if (inode_group)
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inode_node = srcu_dereference(inode_node->next,
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&fsnotify_mark_srcu);
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if (vfsmount_group)
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vfsmount_node = srcu_dereference(vfsmount_node->next,
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&fsnotify_mark_srcu);
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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, idx);
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/*
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* fsnotify_create_event() took a reference so the event can't be cleaned
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* up while we are still trying to add it to lists, drop that one.
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*/
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if (event)
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fsnotify_put_event(event);
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return ret;
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}
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EXPORT_SYMBOL_GPL(fsnotify);
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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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return 0;
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}
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core_initcall(fsnotify_init);
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