From ad25f11ed216d5ce3b5566b2f187b59fa3061b40 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 7 Jul 2017 14:51:19 -0400 Subject: dentry name snapshots commit 49d31c2f389acfe83417083e1208422b4091cd9e upstream. take_dentry_name_snapshot() takes a safe snapshot of dentry name; if the name is a short one, it gets copied into caller-supplied structure, otherwise an extra reference to external name is grabbed (those are never modified). In either case the pointer to stable string is stored into the same structure. dentry must be held by the caller of take_dentry_name_snapshot(), but may be freely dropped afterwards - the snapshot will stay until destroyed by release_dentry_name_snapshot(). Intended use: struct name_snapshot s; take_dentry_name_snapshot(&s, dentry); ... access s.name ... release_dentry_name_snapshot(&s); Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name to pass down with event. Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/notify/fsnotify.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs/notify') diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index db39de2dd4cb..a64adc2fced9 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -104,16 +104,20 @@ int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) if (unlikely(!fsnotify_inode_watches_children(p_inode))) __fsnotify_update_child_dentry_flags(p_inode); else if (p_inode->i_fsnotify_mask & mask) { + struct name_snapshot name; + /* we are notifying a parent so come up with the new mask which * specifies these are events which came from a child. */ mask |= FS_EVENT_ON_CHILD; + take_dentry_name_snapshot(&name, dentry); if (path) ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, - dentry->d_name.name, 0); + name.name, 0); else ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, - dentry->d_name.name, 0); + name.name, 0); + release_dentry_name_snapshot(&name); } dput(parent); -- cgit v1.2.3