bcachefs: fsck: Break walk_inode() up into multiple functions

Some refactoring, prep work for algorithm improvements related to
snapshots.

we need to add a bitmap to the list of inodes for "seen this snapshot";
for this bitmap to correctly be available, we'll need to gather the list
of inodes first, and later look up the inode for a given snapshot.

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

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index 3503dabe3871133d6fd09418ac8619182e2dd2b1..7af65030f9d8dcc41494ca836cab8556cd610435 100644 (file)
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -639,26 +639,23 @@ static int add_inode(struct bch_fs *c, struct inode_walker *w,
        }));
 }
 
-static int __walk_inode(struct btree_trans *trans,
-                       struct inode_walker *w, struct bpos pos)
+static int get_inodes_all_snapshots(struct btree_trans *trans,
+                                   struct inode_walker *w, u64 inum)
 {
        struct bch_fs *c = trans->c;
        struct btree_iter iter;
        struct bkey_s_c k;
        u32 restart_count = trans->restart_count;
-       unsigned i;
        int ret;
 
-       pos.snapshot = bch2_snapshot_equiv(c, pos.snapshot);
-
-       if (pos.inode == w->cur_inum)
-               goto lookup_snapshot;
+       if (w->cur_inum == inum)
+               return 0;
 
        w->inodes.nr = 0;
 
-       for_each_btree_key(trans, iter, BTREE_ID_inodes, POS(0, pos.inode),
+       for_each_btree_key(trans, iter, BTREE_ID_inodes, POS(0, inum),
                           BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
-               if (k.k->p.offset != pos.inode)
+               if (k.k->p.offset != inum)
                        break;
 
                if (bkey_is_inode(k.k))
@@ -669,40 +666,62 @@ static int __walk_inode(struct btree_trans *trans,
        if (ret)
                return ret;
 
-       w->cur_inum             = pos.inode;
+       w->cur_inum             = inum;
        w->first_this_inode     = true;
 
        if (trans_was_restarted(trans, restart_count))
                return -BCH_ERR_transaction_restart_nested;
 
-lookup_snapshot:
-       for (i = 0; i < w->inodes.nr; i++)
-               if (bch2_snapshot_is_ancestor(c, pos.snapshot, w->inodes.data[i].snapshot))
+       return 0;
+}
+
+static struct inode_walker_entry *
+lookup_inode_for_snapshot(struct bch_fs *c,
+                         struct inode_walker *w, u32 snapshot)
+{
+       struct inode_walker_entry *i;
+
+       snapshot = bch2_snapshot_equiv(c, snapshot);
+
+       darray_for_each(w->inodes, i)
+               if (bch2_snapshot_is_ancestor(c, snapshot, i->snapshot))
                        goto found;
-       return INT_MAX;
+
+       return NULL;
 found:
-       BUG_ON(pos.snapshot > w->inodes.data[i].snapshot);
+       BUG_ON(snapshot > i->snapshot);
 
-       if (pos.snapshot != w->inodes.data[i].snapshot) {
-               struct inode_walker_entry e = w->inodes.data[i];
+       if (snapshot != i->snapshot) {
+               struct inode_walker_entry new = *i;
+               int ret;
 
-               e.snapshot = pos.snapshot;
-               e.count = 0;
+               new.snapshot = snapshot;
+               new.count = 0;
 
                bch_info(c, "have key for inode %llu:%u but have inode in ancestor snapshot %u",
-                        pos.inode, pos.snapshot, w->inodes.data[i].snapshot);
+                        w->cur_inum, snapshot, i->snapshot);
 
-               while (i && w->inodes.data[i - 1].snapshot > pos.snapshot)
+               while (i > w->inodes.data && i[-1].snapshot > snapshot)
                        --i;
 
-               ret = darray_insert_item(&w->inodes, i, e);
+               ret = darray_insert_item(&w->inodes, i - w->inodes.data, new);
                if (ret)
-                       return ret;
+                       return ERR_PTR(ret);
        }
 
        return i;
 }
 
+static struct inode_walker_entry *walk_inode(struct btree_trans *trans,
+                                            struct inode_walker *w, struct bpos pos)
+{
+       int ret = get_inodes_all_snapshots(trans, w, pos.inode);
+       if (ret)
+               return ERR_PTR(ret);
+
+       return lookup_inode_for_snapshot(trans->c, w, pos.snapshot);
+}
+
 static int __get_visible_inodes(struct btree_trans *trans,
                                struct inode_walker *w,
                                struct snapshots_seen *s,
@@ -1300,11 +1319,12 @@ static int check_extent(struct btree_trans *trans, struct btree_iter *iter,
        if (ret)
                goto err;
 
-       ret = __walk_inode(trans, inode, equiv);
-       if (ret < 0)
+       i = walk_inode(trans, inode, equiv);
+       ret = PTR_ERR_OR_ZERO(i);
+       if (ret)
                goto err;
 
-       if (fsck_err_on(ret == INT_MAX, c,
+       if (fsck_err_on(!i, c,
                        "extent in missing inode:\n  %s",
                        (printbuf_reset(&buf),
                         bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
@@ -1313,13 +1333,8 @@ static int check_extent(struct btree_trans *trans, struct btree_iter *iter,
                goto out;
        }
 
-       if (ret == INT_MAX) {
-               ret = 0;
+       if (!i)
                goto out;
-       }
-
-       i = inode->inodes.data + ret;
-       ret = 0;
 
        if (fsck_err_on(!S_ISREG(i->inode.bi_mode) &&
                        !S_ISLNK(i->inode.bi_mode), c,
@@ -1625,7 +1640,8 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 
        BUG_ON(!iter->path->should_be_locked);
 
-       ret = __walk_inode(trans, dir, equiv);
+       i = walk_inode(trans, dir, equiv);
+       ret = PTR_ERR_OR_ZERO(i);
        if (ret < 0)
                goto err;
 
@@ -1633,7 +1649,7 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
                *hash_info = bch2_hash_info_init(c, &dir->inodes.data[0].inode);
        dir->first_this_inode = false;
 
-       if (fsck_err_on(ret == INT_MAX, c,
+       if (fsck_err_on(!i, c,
                        "dirent in nonexisting directory:\n%s",
                        (printbuf_reset(&buf),
                         bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
@@ -1642,13 +1658,8 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
                goto out;
        }
 
-       if (ret == INT_MAX) {
-               ret = 0;
+       if (!i)
                goto out;
-       }
-
-       i = dir->inodes.data + ret;
-       ret = 0;
 
        if (fsck_err_on(!S_ISDIR(i->inode.bi_mode), c,
                        "dirent in non directory inode type %s:\n%s",
@@ -1802,30 +1813,30 @@ static int check_xattr(struct btree_trans *trans, struct btree_iter *iter,
                       struct inode_walker *inode)
 {
        struct bch_fs *c = trans->c;
+       struct inode_walker_entry *i;
        int ret;
 
        ret = check_key_has_snapshot(trans, iter, k);
        if (ret)
                return ret;
 
-       ret = __walk_inode(trans, inode, k.k->p);
-       if (ret < 0)
+       i = walk_inode(trans, inode, k.k->p);
+       ret = PTR_ERR_OR_ZERO(i);
+       if (ret)
                return ret;
 
        if (inode->first_this_inode)
                *hash_info = bch2_hash_info_init(c, &inode->inodes.data[0].inode);
        inode->first_this_inode = false;
 
-       if (fsck_err_on(ret == INT_MAX, c,
+       if (fsck_err_on(!i, c,
                        "xattr for missing inode %llu",
                        k.k->p.inode))
                return bch2_btree_delete_at(trans, iter, 0);
 
-       if (ret == INT_MAX)
+       if (!i)
                return 0;
 
-       ret = 0;
-
        ret = hash_check_key(trans, bch2_xattr_hash_desc, hash_info, iter, k);
 fsck_err:
        if (ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart))