From ea5b778a8b98c85a87d66bf844904f9c3802b869 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 14 Jan 2011 19:10:03 +0000 Subject: Unexport do_add_mount() and add in follow_automount(), not ->d_automount() Unexport do_add_mount() and make ->d_automount() return the vfsmount to be added rather than calling do_add_mount() itself. follow_automount() will then do the addition. This slightly complicates things as ->d_automount() normally wants to add the new vfsmount to an expiration list and start an expiration timer. The problem with that is that the vfsmount will be deleted if it has a refcount of 1 and the timer will not repeat if the expiration list is empty. To this end, we require the vfsmount to be returned from d_automount() with a refcount of (at least) 2. One of these refs will be dropped unconditionally. In addition, follow_automount() must get a 3rd ref around the call to do_add_mount() lest it eat a ref and return an error, leaving the mount we have open to being expired as we would otherwise have only 1 ref on it. d_automount() should also add the the vfsmount to the expiration list (by calling mnt_set_expiry()) and start the expiration timer before returning, if this mechanism is to be used. The vfsmount will be unlinked from the expiration list by follow_automount() if do_add_mount() fails. This patch also fixes the call to do_add_mount() for AFS to propagate the mount flags from the parent vfsmount. Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/nfs/namespace.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-) (limited to 'fs/nfs') diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c index f3fbb1bf3f1..f32b8603dca 100644 --- a/fs/nfs/namespace.c +++ b/fs/nfs/namespace.c @@ -149,26 +149,10 @@ struct vfsmount *nfs_d_automount(struct path *path) if (IS_ERR(mnt)) goto out; - mntget(mnt); - err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE, - &nfs_automount_list); - switch (err) { - case 0: - dprintk("%s: done, success\n", __func__); - schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); - break; - case -EBUSY: - /* someone else made a mount here whilst we were busy */ - mntput(mnt); - dprintk("%s: done, collision\n", __func__); - mnt = NULL; - break; - default: - mntput(mnt); - dprintk("%s: done, error %d\n", __func__, err); - mnt = ERR_PTR(err); - break; - } + dprintk("%s: done, success\n", __func__); + mntget(mnt); /* prevent immediate expiration */ + mnt_set_expiry(mnt, &nfs_automount_list); + schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); out: nfs_free_fattr(fattr); -- cgit v1.2.3