diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2019-06-30 19:18:53 -0400 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2019-07-16 22:50:11 -0400 |
commit | 2763d11912317a12318135ca03e592bb6df65624 (patch) | |
tree | 1a6c87b01ca0debc003a888b2e4ded3c9c11daeb | |
parent | 4edbe133f851c9e3a2f2a1db367e826b01e72594 (diff) | |
download | linux-2763d11912317a12318135ca03e592bb6df65624.tar.bz2 |
get rid of detach_mnt()
Lift getting the original mount (dentry is actually not needed at all)
of the mountpoint into the callers - to do_move_mount() and pivot_root()
level. That simplifies the cleanup in those and allows to get saner
arguments for attach_mnt_recursive().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r-- | fs/namespace.c | 62 |
1 files changed, 28 insertions, 34 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index e0902fda6f07..46316ba15615 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -823,16 +823,6 @@ static struct mountpoint *unhash_mnt(struct mount *mnt) /* * vfsmount lock must be held for write */ -static void detach_mnt(struct mount *mnt, struct path *old_path) -{ - old_path->dentry = dget(mnt->mnt_mountpoint); - old_path->mnt = &mnt->mnt_parent->mnt; - put_mountpoint(unhash_mnt(mnt)); -} - -/* - * vfsmount lock must be held for write - */ static void umount_mnt(struct mount *mnt) { put_mountpoint(unhash_mnt(mnt)); @@ -2045,7 +2035,7 @@ int count_mounts(struct mnt_namespace *ns, struct mount *mnt) static int attach_recursive_mnt(struct mount *source_mnt, struct mount *dest_mnt, struct mountpoint *dest_mp, - struct path *parent_path) + bool moving) { struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; HLIST_HEAD(tree_list); @@ -2063,7 +2053,7 @@ static int attach_recursive_mnt(struct mount *source_mnt, return PTR_ERR(smp); /* Is there space to add these mounts to the mount namespace? */ - if (!parent_path) { + if (!moving) { err = count_mounts(ns, source_mnt); if (err) goto out; @@ -2082,8 +2072,8 @@ static int attach_recursive_mnt(struct mount *source_mnt, } else { lock_mount_hash(); } - if (parent_path) { - detach_mnt(source_mnt, parent_path); + if (moving) { + unhash_mnt(source_mnt); attach_mnt(source_mnt, dest_mnt, dest_mp); touch_mnt_namespace(source_mnt->mnt_ns); } else { @@ -2181,7 +2171,7 @@ static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) d_is_dir(mnt->mnt.mnt_root)) return -ENOTDIR; - return attach_recursive_mnt(mnt, p, mp, NULL); + return attach_recursive_mnt(mnt, p, mp, false); } /* @@ -2574,11 +2564,11 @@ out: static int do_move_mount(struct path *old_path, struct path *new_path) { - struct path parent_path = {.mnt = NULL, .dentry = NULL}; struct mnt_namespace *ns; struct mount *p; struct mount *old; - struct mountpoint *mp; + struct mount *parent; + struct mountpoint *mp, *old_mp; int err; bool attached; @@ -2588,7 +2578,9 @@ static int do_move_mount(struct path *old_path, struct path *new_path) old = real_mount(old_path->mnt); p = real_mount(new_path->mnt); + parent = old->mnt_parent; attached = mnt_has_parent(old); + old_mp = old->mnt_mp; ns = old->mnt_ns; err = -EINVAL; @@ -2616,7 +2608,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path) /* * Don't move a mount residing in a shared parent. */ - if (attached && IS_MNT_SHARED(old->mnt_parent)) + if (attached && IS_MNT_SHARED(parent)) goto out; /* * Don't move a mount tree containing unbindable mounts to a destination @@ -2632,18 +2624,21 @@ static int do_move_mount(struct path *old_path, struct path *new_path) goto out; err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, - attached ? &parent_path : NULL); + attached); if (err) goto out; /* if the mount is moved, it should no longer be expire * automatically */ list_del_init(&old->mnt_expire); + if (attached) + put_mountpoint(old_mp); out: unlock_mount(mp); if (!err) { - path_put(&parent_path); - if (!attached) + if (attached) + mntput_no_expire(parent); + else free_mnt_ns(ns); } return err; @@ -3586,8 +3581,8 @@ EXPORT_SYMBOL(path_is_under); SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, const char __user *, put_old) { - struct path new, old, parent_path, root_parent, root; - struct mount *new_mnt, *root_mnt, *old_mnt; + struct path new, old, root; + struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; struct mountpoint *old_mp, *root_mp; int error; @@ -3616,9 +3611,11 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, new_mnt = real_mount(new.mnt); root_mnt = real_mount(root.mnt); old_mnt = real_mount(old.mnt); + ex_parent = new_mnt->mnt_parent; + root_parent = root_mnt->mnt_parent; if (IS_MNT_SHARED(old_mnt) || - IS_MNT_SHARED(new_mnt->mnt_parent) || - IS_MNT_SHARED(root_mnt->mnt_parent)) + IS_MNT_SHARED(ex_parent) || + IS_MNT_SHARED(root_parent)) goto out4; if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) goto out4; @@ -3635,7 +3632,6 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, goto out4; /* not a mountpoint */ if (!mnt_has_parent(root_mnt)) goto out4; /* not attached */ - root_mp = root_mnt->mnt_mp; if (new.mnt->mnt_root != new.dentry) goto out4; /* not a mountpoint */ if (!mnt_has_parent(new_mnt)) @@ -3646,10 +3642,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, /* make certain new is below the root */ if (!is_path_reachable(new_mnt, new.dentry, &root)) goto out4; - root_mp->m_count++; /* pin it so it won't go away */ lock_mount_hash(); - detach_mnt(new_mnt, &parent_path); - detach_mnt(root_mnt, &root_parent); + umount_mnt(new_mnt); + root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { new_mnt->mnt.mnt_flags |= MNT_LOCKED; root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; @@ -3657,7 +3652,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, /* mount old root on put_old */ attach_mnt(root_mnt, old_mnt, old_mp); /* mount new_root on / */ - attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp); + attach_mnt(new_mnt, root_parent, root_mp); + mnt_add_count(root_parent, -1); touch_mnt_namespace(current->nsproxy->mnt_ns); /* A moved mount should not expire automatically */ list_del_init(&new_mnt->mnt_expire); @@ -3667,10 +3663,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, error = 0; out4: unlock_mount(old_mp); - if (!error) { - path_put(&root_parent); - path_put(&parent_path); - } + if (!error) + mntput_no_expire(ex_parent); out3: path_put(&root); out2: |