diff options
author | David Howells <dhowells@redhat.com> | 2011-01-14 19:10:03 (GMT) |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-01-16 01:07:48 (GMT) |
commit | ea5b778a8b98c85a87d66bf844904f9c3802b869 (patch) | |
tree | baa56cbe1a907d76341f2cad53e16569cc1d3288 /fs/namespace.c | |
parent | ab90911ff90cdab59b31c045c3f0ae480d14f29d (diff) | |
download | linux-fsl-qoriq-ea5b778a8b98c85a87d66bf844904f9c3802b869.tar.xz |
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 <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index d94ccd6..bfcb701 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1925,15 +1925,14 @@ static int do_new_mount(struct path *path, char *type, int flags, if (IS_ERR(mnt)) return PTR_ERR(mnt); - return do_add_mount(mnt, path, mnt_flags, NULL); + return do_add_mount(mnt, path, mnt_flags); } /* * add a mount into a namespace's mount tree - * - provide the option of adding the new mount to an expiration list + * - this unconditionally eats one of the caller's references to newmnt. */ -int do_add_mount(struct vfsmount *newmnt, struct path *path, - int mnt_flags, struct list_head *fslist) +int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags) { int err; @@ -1963,9 +1962,6 @@ int do_add_mount(struct vfsmount *newmnt, struct path *path, if ((err = graft_tree(newmnt, path))) goto unlock; - if (fslist) /* add to the specified expiration list */ - list_add_tail(&newmnt->mnt_expire, fslist); - up_write(&namespace_sem); return 0; @@ -1975,7 +1971,36 @@ unlock: return err; } -EXPORT_SYMBOL_GPL(do_add_mount); +/** + * mnt_set_expiry - Put a mount on an expiration list + * @mnt: The mount to list. + * @expiry_list: The list to add the mount to. + */ +void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) +{ + down_write(&namespace_sem); + br_write_lock(vfsmount_lock); + + list_add_tail(&mnt->mnt_expire, expiry_list); + + br_write_unlock(vfsmount_lock); + up_write(&namespace_sem); +} +EXPORT_SYMBOL(mnt_set_expiry); + +/* + * Remove a vfsmount from any expiration list it may be on + */ +void mnt_clear_expiry(struct vfsmount *mnt) +{ + if (!list_empty(&mnt->mnt_expire)) { + down_write(&namespace_sem); + br_write_lock(vfsmount_lock); + list_del_init(&mnt->mnt_expire); + br_write_unlock(vfsmount_lock); + up_write(&namespace_sem); + } +} /* * process a list of expirable mountpoints with the intent of discarding any |