bcachefs: Fix deleted inode check for dirs

We could delete directories transactionally on rmdir()/unlink(), but we
don't; instead, like with regular files we wait for the VFS to call
evict().

That means that our check for directories in the deleted inodes btree is
wrong - the check should be for non-empty directories.

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

Author: Kent Overstreet

fs/bcachefs/dirent.c

@@ -485,20 +485,15 @@ u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 	return ret;
 }
 
-int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
+int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32 snapshot)
 {
 	struct btree_iter iter;
 	struct bkey_s_c k;
-	u32 snapshot;
 	int ret;
 
-	ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
-	if (ret)
-		return ret;
-
 	for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
-			   SPOS(dir.inum, 0, snapshot),
-			   POS(dir.inum, U64_MAX), 0, k, ret)
+			   SPOS(dir, 0, snapshot),
+			   POS(dir, U64_MAX), 0, k, ret)
 		if (k.k->type == KEY_TYPE_dirent) {
 			ret = -ENOTEMPTY;
 			break;
@@ -508,6 +503,14 @@ int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 	return ret;
 }
 
+int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
+{
+	u32 snapshot;
+
+	return bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot) ?:
+		bch2_empty_dir_snapshot(trans, dir.inum, snapshot);
+}
+
 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 {
 	struct btree_trans *trans = bch2_trans_get(c);

fs/bcachefs/dirent.h

@@ -64,6 +64,7 @@ u64 bch2_dirent_lookup(struct bch_fs *, subvol_inum,
 		       const struct bch_hash_info *,
 		       const struct qstr *, subvol_inum *);
 
+int bch2_empty_dir_snapshot(struct btree_trans *, u64, u32);
 int bch2_empty_dir_trans(struct btree_trans *, subvol_inum);
 int bch2_readdir(struct bch_fs *, subvol_inum, struct dir_context *);
 

fs/bcachefs/inode.c

@@ -7,6 +7,7 @@
 #include "btree_update.h"
 #include "buckets.h"
 #include "compress.h"
+#include "dirent.h"
 #include "error.h"
 #include "extents.h"
 #include "extent_update.h"
@@ -1093,11 +1094,15 @@ static int may_delete_deleted_inode(struct btree_trans *trans,
 	if (ret)
 		goto out;
 
-	if (fsck_err_on(S_ISDIR(inode.bi_mode), c,
-			deleted_inode_is_dir,
-			"directory %llu:%u in deleted_inodes btree",
-			pos.offset, pos.snapshot))
-		goto delete;
+	if (S_ISDIR(inode.bi_mode)) {
+		ret = bch2_empty_dir_snapshot(trans, pos.offset, pos.snapshot);
+		if (fsck_err_on(ret == -ENOTEMPTY, c, deleted_inode_is_dir,
+				"non empty directory %llu:%u in deleted_inodes btree",
+				pos.offset, pos.snapshot))
+			goto delete;
+		if (ret)
+			goto out;
+	}
 
 	if (fsck_err_on(!(inode.bi_flags & BCH_INODE_unlinked), c,
 			deleted_inode_not_unlinked,