| Message ID | 20240606090254.36274-1-jemmywong512@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] Improve readability of copy_tree | expand |
On Thu 06-06-24 17:02:54, Jemmy wrote: > by employing `copy mount tree from src to dst` concept. > This involves renaming the opaque variables (e.g., p, q, r, s) > to be more descriptive, aiming to make the code easier to understand. > > Changes: > mnt -> src_root (root of the tree to copy) > r -> src_child (direct child of the root being cloning) I'd call this src_root_child to distinguish it from a child of "src_parent". Otherwise these names work for me. > p -> src_parent (parent of src_mnt) > s -> src_mnt (current mount being copying) > parent -> dst_parent (parent of dst_child) > q -> dst_mnt (freshly cloned mount) > > Signed-off-by: Jemmy <jemmywong512@gmail.com> Honza > --- > fs/namespace.c | 59 ++++++++++++++++++++++++++------------------------ > 1 file changed, 31 insertions(+), 28 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index 5a51315c6678..0dd43633607b 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -1966,69 +1966,72 @@ static bool mnt_ns_loop(struct dentry *dentry) > return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; > } > > -struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, > +struct mount *copy_tree(struct mount *src_root, struct dentry *dentry, > int flag) > { > - struct mount *res, *p, *q, *r, *parent; > + struct mount *res, *src_parent, *src_child, *src_mnt, > + *dst_parent, *dst_mnt; > > - if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) > + if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(src_root)) > return ERR_PTR(-EINVAL); > > if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) > return ERR_PTR(-EINVAL); > > - res = q = clone_mnt(mnt, dentry, flag); > - if (IS_ERR(q)) > - return q; > + res = dst_mnt = clone_mnt(src_root, dentry, flag); > + if (IS_ERR(dst_mnt)) > + return dst_mnt; > > - q->mnt_mountpoint = mnt->mnt_mountpoint; > + src_parent = src_root; > + dst_mnt->mnt_mountpoint = src_root->mnt_mountpoint; > > - p = mnt; > - list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { > - struct mount *s; > - if (!is_subdir(r->mnt_mountpoint, dentry)) > + list_for_each_entry(src_child, &src_root->mnt_mounts, mnt_child) { > + if (!is_subdir(src_child->mnt_mountpoint, dentry)) > continue; > > - for (s = r; s; s = next_mnt(s, r)) { > + for (src_mnt = src_child; src_mnt; > + src_mnt = next_mnt(src_mnt, src_child)) { > if (!(flag & CL_COPY_UNBINDABLE) && > - IS_MNT_UNBINDABLE(s)) { > - if (s->mnt.mnt_flags & MNT_LOCKED) { > + IS_MNT_UNBINDABLE(src_mnt)) { > + if (src_mnt->mnt.mnt_flags & MNT_LOCKED) { > /* Both unbindable and locked. */ > - q = ERR_PTR(-EPERM); > + dst_mnt = ERR_PTR(-EPERM); > goto out; > } else { > - s = skip_mnt_tree(s); > + src_mnt = skip_mnt_tree(src_mnt); > continue; > } > } > if (!(flag & CL_COPY_MNT_NS_FILE) && > - is_mnt_ns_file(s->mnt.mnt_root)) { > - s = skip_mnt_tree(s); > + is_mnt_ns_file(src_mnt->mnt.mnt_root)) { > + src_mnt = skip_mnt_tree(src_mnt); > continue; > } > - while (p != s->mnt_parent) { > - p = p->mnt_parent; > - q = q->mnt_parent; > + while (src_parent != src_mnt->mnt_parent) { > + src_parent = src_parent->mnt_parent; > + dst_mnt = dst_mnt->mnt_parent; > } > - p = s; > - parent = q; > - q = clone_mnt(p, p->mnt.mnt_root, flag); > - if (IS_ERR(q)) > + > + src_parent = src_mnt; > + dst_parent = dst_mnt; > + dst_mnt = clone_mnt(src_mnt, src_mnt->mnt.mnt_root, flag); > + if (IS_ERR(dst_mnt)) > goto out; > lock_mount_hash(); > - list_add_tail(&q->mnt_list, &res->mnt_list); > - attach_mnt(q, parent, p->mnt_mp, false); > + list_add_tail(&dst_mnt->mnt_list, &res->mnt_list); > + attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp, false); > unlock_mount_hash(); > } > } > return res; > + > out: > if (res) { > lock_mount_hash(); > umount_tree(res, UMOUNT_SYNC); > unlock_mount_hash(); > } > - return q; > + return dst_mnt; > } > > /* Caller should check returned pointer for errors */ > -- > 2.34.1 >
diff --git a/fs/namespace.c b/fs/namespace.c index 5a51315c6678..0dd43633607b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1966,69 +1966,72 @@ static bool mnt_ns_loop(struct dentry *dentry) return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; } -struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, +struct mount *copy_tree(struct mount *src_root, struct dentry *dentry, int flag) { - struct mount *res, *p, *q, *r, *parent; + struct mount *res, *src_parent, *src_child, *src_mnt, + *dst_parent, *dst_mnt; - if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) + if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(src_root)) return ERR_PTR(-EINVAL); if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) return ERR_PTR(-EINVAL); - res = q = clone_mnt(mnt, dentry, flag); - if (IS_ERR(q)) - return q; + res = dst_mnt = clone_mnt(src_root, dentry, flag); + if (IS_ERR(dst_mnt)) + return dst_mnt; - q->mnt_mountpoint = mnt->mnt_mountpoint; + src_parent = src_root; + dst_mnt->mnt_mountpoint = src_root->mnt_mountpoint; - p = mnt; - list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { - struct mount *s; - if (!is_subdir(r->mnt_mountpoint, dentry)) + list_for_each_entry(src_child, &src_root->mnt_mounts, mnt_child) { + if (!is_subdir(src_child->mnt_mountpoint, dentry)) continue; - for (s = r; s; s = next_mnt(s, r)) { + for (src_mnt = src_child; src_mnt; + src_mnt = next_mnt(src_mnt, src_child)) { if (!(flag & CL_COPY_UNBINDABLE) && - IS_MNT_UNBINDABLE(s)) { - if (s->mnt.mnt_flags & MNT_LOCKED) { + IS_MNT_UNBINDABLE(src_mnt)) { + if (src_mnt->mnt.mnt_flags & MNT_LOCKED) { /* Both unbindable and locked. */ - q = ERR_PTR(-EPERM); + dst_mnt = ERR_PTR(-EPERM); goto out; } else { - s = skip_mnt_tree(s); + src_mnt = skip_mnt_tree(src_mnt); continue; } } if (!(flag & CL_COPY_MNT_NS_FILE) && - is_mnt_ns_file(s->mnt.mnt_root)) { - s = skip_mnt_tree(s); + is_mnt_ns_file(src_mnt->mnt.mnt_root)) { + src_mnt = skip_mnt_tree(src_mnt); continue; } - while (p != s->mnt_parent) { - p = p->mnt_parent; - q = q->mnt_parent; + while (src_parent != src_mnt->mnt_parent) { + src_parent = src_parent->mnt_parent; + dst_mnt = dst_mnt->mnt_parent; } - p = s; - parent = q; - q = clone_mnt(p, p->mnt.mnt_root, flag); - if (IS_ERR(q)) + + src_parent = src_mnt; + dst_parent = dst_mnt; + dst_mnt = clone_mnt(src_mnt, src_mnt->mnt.mnt_root, flag); + if (IS_ERR(dst_mnt)) goto out; lock_mount_hash(); - list_add_tail(&q->mnt_list, &res->mnt_list); - attach_mnt(q, parent, p->mnt_mp, false); + list_add_tail(&dst_mnt->mnt_list, &res->mnt_list); + attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp, false); unlock_mount_hash(); } } return res; + out: if (res) { lock_mount_hash(); umount_tree(res, UMOUNT_SYNC); unlock_mount_hash(); } - return q; + return dst_mnt; } /* Caller should check returned pointer for errors */
by employing `copy mount tree from src to dst` concept. This involves renaming the opaque variables (e.g., p, q, r, s) to be more descriptive, aiming to make the code easier to understand. Changes: mnt -> src_root (root of the tree to copy) r -> src_child (direct child of the root being cloning) p -> src_parent (parent of src_mnt) s -> src_mnt (current mount being copying) parent -> dst_parent (parent of dst_child) q -> dst_mnt (freshly cloned mount) Signed-off-by: Jemmy <jemmywong512@gmail.com> --- fs/namespace.c | 59 ++++++++++++++++++++++++++------------------------ 1 file changed, 31 insertions(+), 28 deletions(-)