From 07c7530dd46728e25e938d0eb291f8085435c365 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 3 Feb 2014 14:09:08 -0500 Subject: kernfs: invoke dir_ops while holding active ref of the target node kernfs_dir_ops are currently being invoked without any active reference, which makes it tricky for the invoked operations to determine whether the objects associated those nodes are safe to access and will remain that way for the duration of such operations. kernfs already has active_ref mechanism to deal with this which makes the removal of a given node the synchronization point for gating the file operations. There's no reason for dir_ops to be any different. Update the dir_ops handling so that active_ref is held while the dir_ops are executing. This guarantees that while a dir_ops is executing the target nodes stay alive. As kernfs_dir_ops doesn't have any in-kernel user at this point, this doesn't affect anybody. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/kernfs/dir.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) (limited to 'fs/kernfs') diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8c63ae1bccb6..bfbfb48f4ad8 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -654,22 +654,36 @@ static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry, { struct kernfs_node *parent = dir->i_private; struct kernfs_dir_ops *kdops = kernfs_root(parent)->dir_ops; + int ret; if (!kdops || !kdops->mkdir) return -EPERM; - return kdops->mkdir(parent, dentry->d_name.name, mode); + if (!kernfs_get_active(parent)) + return -ENODEV; + + ret = kdops->mkdir(parent, dentry->d_name.name, mode); + + kernfs_put_active(parent); + return ret; } static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) { struct kernfs_node *kn = dentry->d_fsdata; struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; + int ret; if (!kdops || !kdops->rmdir) return -EPERM; - return kdops->rmdir(kn); + if (!kernfs_get_active(kn)) + return -ENODEV; + + ret = kdops->rmdir(kn); + + kernfs_put_active(kn); + return ret; } static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, @@ -678,11 +692,24 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, struct kernfs_node *kn = old_dentry->d_fsdata; struct kernfs_node *new_parent = new_dir->i_private; struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; + int ret; if (!kdops || !kdops->rename) return -EPERM; - return kdops->rename(kn, new_parent, new_dentry->d_name.name); + if (!kernfs_get_active(kn)) + return -ENODEV; + + if (!kernfs_get_active(new_parent)) { + kernfs_put_active(kn); + return -ENODEV; + } + + ret = kdops->rename(kn, new_parent, new_dentry->d_name.name); + + kernfs_put_active(new_parent); + kernfs_put_active(kn); + return ret; } const struct inode_operations kernfs_dir_iops = { -- cgit v1.2.3