cannot access 'fsmount': Permission denied d????????? ? ? ? ? ? fsmount nbs@pubbeta1-nostest2:/tmp$ cd fsmount -bash: cd: fsmount: Permission denied # root user cannot access 'fsmount': Permission denied d????????? ? ? ? ? ? fsmount root@pubbeta1-nostest2:/tmp# cd fsmount bash: cd: fsmount: Permission denied© XXX Page 4 of unt$ # nbs user nbs@pubbeta1-nostest2:/tmp$ ls -l | grep fsmount ls: cannot access 'fsmount': Permission denied d????????? ? ? ? ? ? fsmount nbs@pubbeta1-nostest2:/tmp$

= -1 EACCES (Permission denied) # O_WRONLY|O_APPEND # in.txt 0400 nbs@pubbeta1-nostest2:/tmp/fsmount$ strace ./main ... open("in.txt", O_WRONLY|O_APPEND) = -1 EACCES (Permission denied) # O_RDWR nbs@pubbeta1-nostest2:/tmp/fsmount$ strace ./main ... open("in.txt", O_RDWR) = -1 EACCES (Permission denied) # O_RDWR # in.txt 0777© XXX Page 8 of 23 nbs@pubbeta1-nostest2:/tmp/fsmount$ strace 6/+/refs/heads/jb-dev/sysroot/usr/include/asm-generic/fcntl.h https://www.gnu.org/software/libc/manual/html_node/Permission-Bits.html https://xinqiu.gitbooks.io/linux-insides-cn/content/SysCall/linux-syscall-5.html https://zhuanlan