pnode: pass mountpoint directly

Currently, we use a global variable to stash the destination
mountpoint. All global variables are changed in propagate_one(). The
mountpoint variable is one of the few which doesn't change after
initialization. Instead, just pass the destination mountpoint directly
making it easy to verify directly in propagate_mnt() that the
destination mountpoint never changes.

Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Message-Id: <20230202-fs-move-mount-replace-v2-2-f53cd31d6392@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/pnode.c b/fs/pnode.c
index 468e4e65a615d770919e0d952e17d0f4f1a7c02f..3cede8b18c8b6ff385815ae51e911b6b6af81e56 100644 (file)
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -214,7 +214,6 @@ static struct mount *next_group(struct mount *m, struct mount *origin)
 
 /* all accesses are serialized by namespace_sem */
 static struct mount *last_dest, *first_source, *last_source, *dest_master;
-static struct mountpoint *mp;
 static struct hlist_head *list;
 
 static inline bool peers(struct mount *m1, struct mount *m2)
@@ -222,7 +221,7 @@ static inline bool peers(struct mount *m1, struct mount *m2)
        return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id;
 }
 
-static int propagate_one(struct mount *m)
+static int propagate_one(struct mount *m, struct mountpoint *dest_mp)
 {
        struct mount *child;
        int type;
@@ -230,7 +229,7 @@ static int propagate_one(struct mount *m)
        if (IS_MNT_NEW(m))
                return 0;
        /* skip if mountpoint isn't covered by it */
-       if (!is_subdir(mp->m_dentry, m->mnt.mnt_root))
+       if (!is_subdir(dest_mp->m_dentry, m->mnt.mnt_root))
                return 0;
        if (peers(m, last_dest)) {
                type = CL_MAKE_SHARED;
@@ -262,7 +261,7 @@ static int propagate_one(struct mount *m)
        if (IS_ERR(child))
                return PTR_ERR(child);
        read_seqlock_excl(&mount_lock);
-       mnt_set_mountpoint(m, mp, child);
+       mnt_set_mountpoint(m, dest_mp, child);
        if (m->mnt_master != dest_master)
                SET_MNT_MARK(m->mnt_master);
        read_sequnlock_excl(&mount_lock);
@@ -299,13 +298,12 @@ int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
        last_dest = dest_mnt;
        first_source = source_mnt;
        last_source = source_mnt;
-       mp = dest_mp;
        list = tree_list;
        dest_master = dest_mnt->mnt_master;
 
        /* all peers of dest_mnt, except dest_mnt itself */
        for (n = next_peer(dest_mnt); n != dest_mnt; n = next_peer(n)) {
-               ret = propagate_one(n);
+               ret = propagate_one(n, dest_mp);
                if (ret)
                        goto out;
        }
@@ -316,7 +314,7 @@ int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
                /* everything in that slave group */
                n = m;
                do {
-                       ret = propagate_one(n);
+                       ret = propagate_one(n, dest_mp);
                        if (ret)
                                goto out;
                        n = next_peer(n);