From c28f7e56e9d95fb531dc3be8df2e7f52bee76d21 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 21 May 2009 17:01:29 -0400 Subject: fsnotify: parent event notification inotify and dnotify both use a similar parent notification mechanism. We add a generic parent notification mechanism to fsnotify for both of these to use. This new machanism also adds the dentry flag optimization which exists for inotify to dnotify. Signed-off-by: Eric Paris Acked-by: Al Viro Cc: Christoph Hellwig --- fs/notify/fsnotify.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++ fs/notify/fsnotify.h | 5 +++ fs/notify/inode_mark.c | 17 ++++++++++ 3 files changed, 113 insertions(+) (limited to 'fs/notify') diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index d5654629c65..7fc760067a6 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -34,6 +34,97 @@ void __fsnotify_inode_delete(struct inode *inode) } EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); +/* + * Given an inode, first check if we care what happens to our children. Inotify + * and dnotify both tell their parents about events. If we care about any event + * on a child we run all of our children and set a dentry flag saying that the + * parent cares. Thus when an event happens on a child it can quickly tell if + * if there is a need to find a parent and send the event to the parent. + */ +void __fsnotify_update_child_dentry_flags(struct inode *inode) +{ + struct dentry *alias; + int watched; + + if (!S_ISDIR(inode->i_mode)) + return; + + /* determine if the children should tell inode about their events */ + watched = fsnotify_inode_watches_children(inode); + + spin_lock(&dcache_lock); + /* run all of the dentries associated with this inode. Since this is a + * directory, there damn well better only be one item on this list */ + list_for_each_entry(alias, &inode->i_dentry, d_alias) { + struct dentry *child; + + /* run all of the children of the original inode and fix their + * d_flags to indicate parental interest (their parent is the + * original inode) */ + list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { + if (!child->d_inode) + continue; + + spin_lock(&child->d_lock); + if (watched) + child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; + else + child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; + spin_unlock(&child->d_lock); + } + } + spin_unlock(&dcache_lock); +} + +/* Notify this dentry's parent about a child's events. */ +void __fsnotify_parent(struct dentry *dentry, __u32 mask) +{ + struct dentry *parent; + struct inode *p_inode; + bool send = false; + bool should_update_children = false; + + if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) + return; + + spin_lock(&dentry->d_lock); + parent = dentry->d_parent; + p_inode = parent->d_inode; + + if (fsnotify_inode_watches_children(p_inode)) { + if (p_inode->i_fsnotify_mask & mask) { + dget(parent); + send = true; + } + } else { + /* + * The parent doesn't care about events on it's children but + * at least one child thought it did. We need to run all the + * children and update their d_flags to let them know p_inode + * doesn't care about them any more. + */ + dget(parent); + should_update_children = true; + } + + spin_unlock(&dentry->d_lock); + + if (send) { + /* we are notifying a parent so come up with the new mask which + * specifies these are events which came from a child. */ + mask |= FS_EVENT_ON_CHILD; + + fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE); + dput(parent); + } + + if (unlikely(should_update_children)) { + __fsnotify_update_child_dentry_flags(p_inode); + dput(parent); + } +} +EXPORT_SYMBOL_GPL(__fsnotify_parent); + /* * This is the main call to fsnotify. The VFS calls into hook specific functions * in linux/fsnotify.h. Those functions then in turn call here. Here will call diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h index 8ebcbe893c9..83b8ec0a8ec 100644 --- a/fs/notify/fsnotify.h +++ b/fs/notify/fsnotify.h @@ -17,4 +17,9 @@ extern __u32 fsnotify_mask; extern void fsnotify_final_destroy_group(struct fsnotify_group *group); /* run the list of all marks associated with inode and flag them to be freed */ extern void fsnotify_clear_marks_by_inode(struct inode *inode); +/* + * update the dentry->d_flags of all of inode's children to indicate if inode cares + * about events that happen to its children. + */ +extern void __fsnotify_update_child_dentry_flags(struct inode *inode); #endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c index cdc15414697..a39534845b2 100644 --- a/fs/notify/inode_mark.c +++ b/fs/notify/inode_mark.c @@ -131,6 +131,8 @@ void fsnotify_recalc_inode_mask(struct inode *inode) spin_lock(&inode->i_lock); fsnotify_recalc_inode_mask_locked(inode); spin_unlock(&inode->i_lock); + + __fsnotify_update_child_dentry_flags(inode); } /* @@ -189,6 +191,19 @@ void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry) */ group->ops->freeing_mark(entry, group); + /* + * __fsnotify_update_child_dentry_flags(inode); + * + * I really want to call that, but we can't, we have no idea if the inode + * still exists the second we drop the entry->lock. + * + * The next time an event arrive to this inode from one of it's children + * __fsnotify_parent will see that the inode doesn't care about it's + * children and will update all of these flags then. So really this + * is just a lazy update (and could be a perf win...) + */ + + /* * it's possible that this group tried to destroy itself, but this * this mark was simultaneously being freed by inode. If that's the @@ -323,6 +338,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry, if (lentry) { ret = -EEXIST; fsnotify_put_mark(lentry); + } else { + __fsnotify_update_child_dentry_flags(inode); } return ret; -- cgit v1.2.3