bcachefs: Subvolumes may now be renamed

Files within a subvolume cannot be renamed into another subvolume, but
subvolumes themselves were intended to be.

This implements subvolume renaming - we need to ensure that there's only
a single dirent that points to a subvolume key (not multiple versions in
different snapshots), and we need to ensure that dirent.d_parent_subol
and inode.bi_parent_subvol are updated.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
index 8a4572594545910e429607456280a0e55891df5c..0dfcb194cb1efcd11a520d9c993fbb61a730e34b 100644 (file)
--- a/fs/bcachefs/dirent.c
+++ b/fs/bcachefs/dirent.c
@@ -293,12 +293,10 @@ int bch2_dirent_rename(struct btree_trans *trans,
        struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
        struct bpos dst_pos =
                POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
-       unsigned src_type = 0, dst_type = 0, src_update_flags = 0;
+       unsigned src_update_flags = 0;
+       bool delete_src, delete_dst;
        int ret = 0;
 
-       if (src_dir.subvol != dst_dir.subvol)
-               return -EXDEV;
-
        memset(src_inum, 0, sizeof(*src_inum));
        memset(dst_inum, 0, sizeof(*dst_inum));
 
@@ -319,12 +317,6 @@ int bch2_dirent_rename(struct btree_trans *trans,
        if (ret)
                goto out;
 
-       src_type = bkey_s_c_to_dirent(old_src).v->d_type;
-
-       if (src_type == DT_SUBVOL && mode == BCH_RENAME_EXCHANGE)
-               return -EOPNOTSUPP;
-
-
        /* Lookup dst: */
        if (mode == BCH_RENAME) {
                /*
@@ -352,11 +344,6 @@ int bch2_dirent_rename(struct btree_trans *trans,
                                bkey_s_c_to_dirent(old_dst), dst_inum);
                if (ret)
                        goto out;
-
-               dst_type = bkey_s_c_to_dirent(old_dst).v->d_type;
-
-               if (dst_type == DT_SUBVOL)
-                       return -EOPNOTSUPP;
        }
 
        if (mode != BCH_RENAME_EXCHANGE)
@@ -426,28 +413,55 @@ int bch2_dirent_rename(struct btree_trans *trans,
                }
        }
 
+       if (new_dst->v.d_type == DT_SUBVOL)
+               new_dst->v.d_parent_subvol = cpu_to_le32(dst_dir.subvol);
+
+       if ((mode == BCH_RENAME_EXCHANGE) &&
+           new_src->v.d_type == DT_SUBVOL)
+               new_src->v.d_parent_subvol = cpu_to_le32(src_dir.subvol);
+
        ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
        if (ret)
                goto out;
 out_set_src:
-
        /*
-        * If we're deleting a subvolume, we need to really delete the dirent,
-        * not just emit a whiteout in the current snapshot:
+        * If we're deleting a subvolume we need to really delete the dirent,
+        * not just emit a whiteout in the current snapshot - there can only be
+        * single dirent that points to a given subvolume.
+        *
+        * IOW, we don't maintain multiple versions in different snapshots of
+        * dirents that point to subvolumes - dirents that point to subvolumes
+        * are only visible in one particular subvolume so it's not necessary,
+        * and it would be particularly confusing for fsck to have to deal with.
         */
-       if (src_type == DT_SUBVOL) {
-               bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
-               ret = bch2_btree_iter_traverse(&src_iter);
+       delete_src = bkey_s_c_to_dirent(old_src).v->d_type == DT_SUBVOL &&
+               new_src->k.p.snapshot != old_src.k->p.snapshot;
+
+       delete_dst = old_dst.k &&
+               bkey_s_c_to_dirent(old_dst).v->d_type == DT_SUBVOL &&
+               new_dst->k.p.snapshot != old_dst.k->p.snapshot;
+
+       if (!delete_src || !bkey_deleted(&new_src->k)) {
+               ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
                if (ret)
                        goto out;
+       }
 
-               new_src->k.p = src_iter.pos;
-               src_update_flags |= BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE;
+       if (delete_src) {
+               bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
+               ret =   bch2_btree_iter_traverse(&src_iter) ?:
+                       bch2_btree_delete_at(trans, &src_iter, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+               if (ret)
+                       goto out;
        }
 
-       ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
-       if (ret)
-               goto out;
+       if (delete_dst) {
+               bch2_btree_iter_set_snapshot(&dst_iter, old_dst.k->p.snapshot);
+               ret =   bch2_btree_iter_traverse(&dst_iter) ?:
+                       bch2_btree_delete_at(trans, &dst_iter, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+               if (ret)
+                       goto out;
+       }
 
        if (mode == BCH_RENAME_EXCHANGE)
                *src_offset = new_src->k.p.offset;

diff --git a/fs/bcachefs/fs-common.c b/fs/bcachefs/fs-common.c
index 8ee716e4c2e72e0e265805560b70e27b9f14e4d3..523507e38887bf9fd4aaacf6ece326d04e6edd16 100644 (file)
--- a/fs/bcachefs/fs-common.c
+++ b/fs/bcachefs/fs-common.c
@@ -410,6 +410,21 @@ int bch2_rename_trans(struct btree_trans *trans,
                        goto err;
        }
 
+       /* Can't move across subvolumes, unless it's a subvolume root: */
+       if (src_dir.subvol != dst_dir.subvol &&
+           (!src_inode_u->bi_subvol ||
+            (dst_inum.inum && !dst_inode_u->bi_subvol))) {
+               ret = -EXDEV;
+               goto err;
+       }
+
+       if (src_inode_u->bi_parent_subvol)
+               src_inode_u->bi_parent_subvol = dst_dir.subvol;
+
+       if ((mode == BCH_RENAME_EXCHANGE) &&
+           dst_inode_u->bi_parent_subvol)
+               dst_inode_u->bi_parent_subvol = src_dir.subvol;
+
        src_inode_u->bi_dir             = dst_dir_u->bi_inum;
        src_inode_u->bi_dir_offset      = dst_offset;