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/afs/mntpt.c | 25 ++++++------------------- 1 file changed, 6 insertions(+), 19 deletions(-) (limited to 'fs/afs') diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c index d23b2e344a78..aa59184151d0 100644 --- a/fs/afs/mntpt.c +++ b/fs/afs/mntpt.c @@ -241,7 +241,6 @@ error_no_devname: struct vfsmount *afs_d_automount(struct path *path) { struct vfsmount *newmnt; - int err; _enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name); @@ -249,24 +248,12 @@ struct vfsmount *afs_d_automount(struct path *path) if (IS_ERR(newmnt)) return newmnt; - mntget(newmnt); - err = do_add_mount(newmnt, path, MNT_SHRINKABLE, &afs_vfsmounts); - switch (err) { - case 0: - queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, - afs_mntpt_expiry_timeout * HZ); - _leave(" = %p {%s}", newmnt, newmnt->mnt_devname); - return newmnt; - case -EBUSY: - /* someone else made a mount here whilst we were busy */ - mntput(newmnt); - _leave(" = NULL [EBUSY]"); - return NULL; - default: - mntput(newmnt); - _leave(" = %d", err); - return ERR_PTR(err); - } + mntget(newmnt); /* prevent immediate expiration */ + mnt_set_expiry(newmnt, &afs_vfsmounts); + queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, + afs_mntpt_expiry_timeout * HZ); + _leave(" = %p {%s}", newmnt, newmnt->mnt_devname); + return newmnt; } /* -- cgit v1.2.3