bcachefs: Add logging to bch2_inode_peek() & related

Add error messages when we fail to lookup an inode, and also add a few
missing bch2_err_class() calls.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs.h

@@ -294,8 +294,8 @@ do {									\
 
 #define bch_err_fn(_c, _ret)						\
 	 bch_err(_c, "%s(): error %s", __func__, bch2_err_str(_ret))
-#define bch_err_msg(_c, _ret, _msg)					\
-	 bch_err(_c, "%s(): error " _msg " %s", __func__, bch2_err_str(_ret))
+#define bch_err_msg(_c, _ret, _msg, ...)				\
+	 bch_err(_c, "%s(): error " _msg " %s", __func__, ##__VA_ARGS__, bch2_err_str(_ret))
 
 #define bch_verbose(c, fmt, ...)					\
 do {									\

fs/bcachefs/fs.c

@@ -203,7 +203,7 @@ struct inode *bch2_vfs_inode_get(struct bch_fs *c, subvol_inum inum)
 
 	if (ret) {
 		iget_failed(&inode->v);
-		return ERR_PTR(ret);
+		return ERR_PTR(bch2_err_class(ret));
 	}
 
 	mutex_lock(&c->vfs_inodes_lock);
@@ -1000,11 +1000,16 @@ static int bch2_vfs_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct bch_inode_info *inode = file_bch_inode(file);
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
+	int ret;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 
-	return bch2_readdir(c, inode_inum(inode), ctx);
+	ret = bch2_readdir(c, inode_inum(inode), ctx);
+	if (ret)
+		bch_err_fn(c, ret);
+
+	return bch2_err_class(ret);
 }
 
 static const struct file_operations bch_file_operations = {

fs/bcachefs/inode.c

@@ -348,6 +348,8 @@ int bch2_inode_peek(struct btree_trans *trans,
 	return 0;
 err:
 	bch2_trans_iter_exit(trans, iter);
+	if (!bch2_err_matches(ret, BCH_ERR_transaction_restart))
+		bch_err_msg(trans->c, ret, "looking up inum %u:%llu:", inum.subvol, inum.inum);
 	return ret;
 }