debug fcntl F_SETLK[W] with bpftrace

fcntl_setlk.bt

#include <fcntl.h>

/* Usage example: bpftrace fcntl_setlk.bt podman */

kretfunc:vmlinux:fcntl_setlk / $# == 0 || comm == str($1) / {
	if (args->flock->l_type == F_UNLCK) {
		delete(@pending_locks[pid, args->filp])
	} else if (retval == 0) {
		@pending_locks[pid, args->filp] = 1
	}
	printf(
		"[%d]* comm=%s l_type=%s fd=%-3d file=016x%lx dev=%u:%u ino=%lu [%u:%ld, len=%ld] -> %d: %s\n",
		pid,
		comm,
		args->flock->l_type == F_WRLCK ? "F_WRLCK" : args->flock->l_type == F_UNLCK ? "F_UNLCK" : "F_RDLCK",
		args->fd,
		args->filp,
		args->filp->f_inode->i_sb->s_dev >> 20, ((uint32) (args->filp->f_inode->i_sb->s_dev << 12)) >> 12,
		args->filp->f_inode->i_ino,
		args->flock->l_whence, args->flock->l_start, args->flock->l_len,
		retval,
		str(args->filp->f_path.dentry->d_name.name)
		/* path(args->filp->f_path) - not allowed? */
	);
}

kfunc:vmlinux:locks_remove_posix / args->filp->f_inode->i_flctx != 0 && ($# == 0 || comm == str($1)) / {
	if (@pending_locks[pid, args->filp] == 1) {
		delete(@pending_locks[pid, args->filp]);
		printf(
			"[%d]* comm=%s locks_remove_posix file=016x%lx dev=%u:%u ino=%lu: %s\n",
			pid,
			comm,
			args->filp,
			args->filp->f_inode->i_sb->s_dev >> 20, ((uint32) (args->filp->f_inode->i_sb->s_dev << 12)) >> 12,
			args->filp->f_inode->i_ino,
			str(args->filp->f_path.dentry->d_name.name)
		);
	}
}

END {
	clear(@pending_locks);
}