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572 lines
17 KiB
572 lines
17 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <[email protected]> |
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*/ |
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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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static 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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|
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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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* However, we should have been called /after/ evict_inodes |
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* removed all zero refcount inodes, in any case. Test to |
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* be sure. |
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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(inode, FS_UNMOUNT); |
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fsnotify_inode_delete(inode); |
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iput_inode = inode; |
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cond_resched(); |
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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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/* Wait for outstanding inode references from connectors */ |
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wait_var_event(&sb->s_fsnotify_inode_refs, |
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!atomic_long_read(&sb->s_fsnotify_inode_refs)); |
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} |
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void fsnotify_sb_delete(struct super_block *sb) |
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{ |
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fsnotify_unmount_inodes(sb); |
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fsnotify_clear_marks_by_sb(sb); |
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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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/* Are inode/sb/mount interested in parent and name info with this event? */ |
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static bool fsnotify_event_needs_parent(struct inode *inode, struct mount *mnt, |
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__u32 mask) |
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{ |
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__u32 marks_mask = 0; |
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/* We only send parent/name to inode/sb/mount for events on non-dir */ |
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if (mask & FS_ISDIR) |
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return false; |
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/* |
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* All events that are possible on child can also may be reported with |
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* parent/name info to inode/sb/mount. Otherwise, a watching parent |
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* could result in events reported with unexpected name info to sb/mount. |
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*/ |
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BUILD_BUG_ON(FS_EVENTS_POSS_ON_CHILD & ~FS_EVENTS_POSS_TO_PARENT); |
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/* Did either inode/sb/mount subscribe for events with parent/name? */ |
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marks_mask |= fsnotify_parent_needed_mask(inode->i_fsnotify_mask); |
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marks_mask |= fsnotify_parent_needed_mask(inode->i_sb->s_fsnotify_mask); |
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if (mnt) |
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marks_mask |= fsnotify_parent_needed_mask(mnt->mnt_fsnotify_mask); |
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/* Did they subscribe for this event with parent/name info? */ |
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return mask & marks_mask; |
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} |
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/* |
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* Notify this dentry's parent about a child's events with child name info |
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* if parent is watching or if inode/sb/mount are interested in events with |
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* parent and name info. |
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* |
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* Notify only the child without name info if parent is not watching and |
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* inode/sb/mount are not interested in events with parent and name info. |
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*/ |
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int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data, |
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int data_type) |
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{ |
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const struct path *path = fsnotify_data_path(data, data_type); |
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struct mount *mnt = path ? real_mount(path->mnt) : NULL; |
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struct inode *inode = d_inode(dentry); |
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struct dentry *parent; |
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bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED; |
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bool parent_needed, parent_interested; |
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__u32 p_mask; |
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struct inode *p_inode = NULL; |
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struct name_snapshot name; |
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struct qstr *file_name = NULL; |
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int ret = 0; |
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/* |
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* Do inode/sb/mount care about parent and name info on non-dir? |
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* Do they care about any event at all? |
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*/ |
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if (!inode->i_fsnotify_marks && !inode->i_sb->s_fsnotify_marks && |
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(!mnt || !mnt->mnt_fsnotify_marks) && !parent_watched) |
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return 0; |
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parent = NULL; |
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parent_needed = fsnotify_event_needs_parent(inode, mnt, mask); |
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if (!parent_watched && !parent_needed) |
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goto notify; |
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/* Does parent inode care about events on children? */ |
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parent = dget_parent(dentry); |
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p_inode = parent->d_inode; |
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p_mask = fsnotify_inode_watches_children(p_inode); |
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if (unlikely(parent_watched && !p_mask)) |
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__fsnotify_update_child_dentry_flags(p_inode); |
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/* |
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* Include parent/name in notification either if some notification |
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* groups require parent info or the parent is interested in this event. |
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*/ |
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parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS; |
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if (parent_needed || parent_interested) { |
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/* When notifying parent, child should be passed as data */ |
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WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type)); |
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/* Notify both parent and child with child name info */ |
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take_dentry_name_snapshot(&name, dentry); |
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file_name = &name.name; |
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if (parent_interested) |
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mask |= FS_EVENT_ON_CHILD; |
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} |
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notify: |
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ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0); |
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if (file_name) |
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release_dentry_name_snapshot(&name); |
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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 fsnotify_handle_inode_event(struct fsnotify_group *group, |
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struct fsnotify_mark *inode_mark, |
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u32 mask, const void *data, int data_type, |
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struct inode *dir, const struct qstr *name, |
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u32 cookie) |
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{ |
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const struct path *path = fsnotify_data_path(data, data_type); |
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struct inode *inode = fsnotify_data_inode(data, data_type); |
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const struct fsnotify_ops *ops = group->ops; |
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if (WARN_ON_ONCE(!ops->handle_inode_event)) |
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return 0; |
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if ((inode_mark->mask & FS_EXCL_UNLINK) && |
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path && d_unlinked(path->dentry)) |
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return 0; |
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/* Check interest of this mark in case event was sent with two marks */ |
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if (!(mask & inode_mark->mask & ALL_FSNOTIFY_EVENTS)) |
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return 0; |
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return ops->handle_inode_event(inode_mark, mask, inode, dir, name, cookie); |
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} |
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static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask, |
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const void *data, int data_type, |
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struct inode *dir, const struct qstr *name, |
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u32 cookie, struct fsnotify_iter_info *iter_info) |
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{ |
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struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info); |
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struct fsnotify_mark *parent_mark = fsnotify_iter_parent_mark(iter_info); |
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int ret; |
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if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) || |
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WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info))) |
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return 0; |
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if (parent_mark) { |
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/* |
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* parent_mark indicates that the parent inode is watching |
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* children and interested in this event, which is an event |
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* possible on child. But is *this mark* watching children and |
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* interested in this event? |
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*/ |
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if (parent_mark->mask & FS_EVENT_ON_CHILD) { |
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ret = fsnotify_handle_inode_event(group, parent_mark, mask, |
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data, data_type, dir, name, 0); |
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if (ret) |
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return ret; |
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} |
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if (!inode_mark) |
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return 0; |
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} |
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if (mask & FS_EVENT_ON_CHILD) { |
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/* |
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* Some events can be sent on both parent dir and child marks |
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* (e.g. FS_ATTRIB). If both parent dir and child are |
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* watching, report the event once to parent dir with name (if |
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* interested) and once to child without name (if interested). |
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* The child watcher is expecting an event without a file name |
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* and without the FS_EVENT_ON_CHILD flag. |
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*/ |
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mask &= ~FS_EVENT_ON_CHILD; |
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dir = NULL; |
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name = NULL; |
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} |
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return fsnotify_handle_inode_event(group, inode_mark, mask, data, data_type, |
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dir, name, cookie); |
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} |
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static int send_to_group(__u32 mask, const void *data, int data_type, |
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struct inode *dir, const struct qstr *file_name, |
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u32 cookie, 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 & ALL_FSNOTIFY_EVENTS); |
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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 mask=%x marks_mask=%x marks_ignored_mask=%x data=%p data_type=%d dir=%p cookie=%d\n", |
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__func__, group, mask, marks_mask, marks_ignored_mask, |
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data, data_type, dir, cookie); |
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if (!(test_mask & marks_mask & ~marks_ignored_mask)) |
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return 0; |
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if (group->ops->handle_event) { |
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return group->ops->handle_event(group, mask, data, data_type, dir, |
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file_name, cookie, iter_info); |
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} |
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return fsnotify_handle_event(group, mask, data, data_type, dir, |
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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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* fsnotify - This is the main call to fsnotify. |
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* |
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* The VFS calls into hook specific functions in linux/fsnotify.h. |
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* Those functions then in turn call here. Here will call out to all of the |
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* registered fsnotify_group. Those groups can then use the notification event |
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* in whatever means they feel necessary. |
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* |
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* @mask: event type and flags |
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* @data: object that event happened on |
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* @data_type: type of object for fanotify_data_XXX() accessors |
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* @dir: optional directory associated with event - |
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* if @file_name is not NULL, this is the directory that |
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* @file_name is relative to |
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* @file_name: optional file name associated with event |
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* @inode: optional inode associated with event - |
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* either @dir or @inode must be non-NULL. |
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* if both are non-NULL event may be reported to both. |
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* @cookie: inotify rename cookie |
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*/ |
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int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, |
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const struct qstr *file_name, struct inode *inode, u32 cookie) |
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{ |
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const struct path *path = fsnotify_data_path(data, data_type); |
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struct fsnotify_iter_info iter_info = {}; |
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struct super_block *sb; |
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struct mount *mnt = NULL; |
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struct inode *parent = NULL; |
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int ret = 0; |
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__u32 test_mask, marks_mask; |
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if (path) |
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mnt = real_mount(path->mnt); |
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if (!inode) { |
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/* Dirent event - report on TYPE_INODE to dir */ |
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inode = dir; |
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} else if (mask & FS_EVENT_ON_CHILD) { |
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/* |
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* Event on child - report on TYPE_PARENT to dir if it is |
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* watching children and on TYPE_INODE to child. |
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*/ |
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parent = dir; |
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} |
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sb = inode->i_sb; |
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|
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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 (!sb->s_fsnotify_marks && |
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(!mnt || !mnt->mnt_fsnotify_marks) && |
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(!inode || !inode->i_fsnotify_marks) && |
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(!parent || !parent->i_fsnotify_marks)) |
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return 0; |
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marks_mask = sb->s_fsnotify_mask; |
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if (mnt) |
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marks_mask |= mnt->mnt_fsnotify_mask; |
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if (inode) |
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marks_mask |= inode->i_fsnotify_mask; |
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if (parent) |
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marks_mask |= parent->i_fsnotify_mask; |
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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 none of the marks care about this type of event. |
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*/ |
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test_mask = (mask & ALL_FSNOTIFY_EVENTS); |
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if (!(mask & FS_MODIFY) && !(test_mask & marks_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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iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] = |
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fsnotify_first_mark(&sb->s_fsnotify_marks); |
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if (mnt) { |
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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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if (inode) { |
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iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] = |
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fsnotify_first_mark(&inode->i_fsnotify_marks); |
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} |
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if (parent) { |
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iter_info.marks[FSNOTIFY_OBJ_TYPE_PARENT] = |
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fsnotify_first_mark(&parent->i_fsnotify_marks); |
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} |
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|
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/* |
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* We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark |
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* ignore masks are properly reflected for mount/sb 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(mask, data, data_type, dir, file_name, |
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cookie, &iter_info); |
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|
|
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); |
|
|
|
static __init int fsnotify_init(void) |
|
{ |
|
int ret; |
|
|
|
BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25); |
|
|
|
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);
|
|
|