fsync: Operation not supported

[ghost]

Steps to reproduce:

1. https://paste.debian.net/plain/1205931
2. Pass any gocryptfs path as an argument.
   Error: fsync /path/: Operation not supported

[rfjakob]

Can confirm for directories but not for normal files (see below)

$ ./a.out /tmp/tmp.4V62WJ9BI6/b/file 
(ok)

$ ./a.out /tmp/tmp.4V62WJ9BI6/b/dir
Error: fsync /tmp/tmp.4V62WJ9BI6/b/dir: Operation not supported

20 extra internet points for minimal reproducer C code:
⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐

[rfjakob]

Relevant gocryptfs -fg -nosyslog -fusedebug log below. Looks like we don't implement FSYNCDIR:

14:22:46.856729 rx 28: LOOKUP n1 ["file"] 5b
14:22:46.856904 tx 28:     OK, {n3 g1 tE=1s tA=1s {M0100644 SZ=0 L=1 1026:1026 B0*4096 i0:22676 A 1627561080.433648 M 1627561080.433647 C 1627561080.432017}}
14:22:46.856946 rx 30: OPEN n3 {O_RDONLY,0x8000} 
14:22:46.856990 tx 30:     OK, {Fh 1 }
14:22:46.857036 rx 32: FSYNC n3 
14:22:46.857048 tx 32:     OK
14:22:46.857110 rx 34: FLUSH n3 {Fh 1} 
14:22:46.857126 tx 34:     OK
14:22:46.857215 rx 36: RELEASE n3 {Fh 1 0x8000  L0} 
14:22:46.857233 tx 36:     OK



14:22:56.038596 rx 38: LOOKUP n1 ["dir"] 4b
14:22:56.038708 tx 38:     OK, {n2 g1 tE=1s tA=1s {M040755 SZ=60 L=2 1026:1026 B0*4096 i0:22672 A 1627561056.976900 M 1627561056.976900 C 1627561056.976900}}
14:22:56.038746 rx 40: OPENDIR n2 
14:22:56.038775 tx 40:     OK, {Fh 1 }
14:22:56.038803 rx 42: FSYNCDIR n2 
14:22:56.038811 tx 42:     95=operation not supported
14:22:56.038869 rx 44: RELEASEDIR n2 {Fh 1 0x8000  L0} 
14:22:56.038875 tx 44:     OK

[ghost]

C code was all @/bremner on #notmuch @ irc.libera.chat. Does this project have an IRC channel?
Will FSYNCDIR be implemented?

[lechner]

With the Debian paste scheduled to expire on 2021-07-30 13:38:48, it seemed prudent to copy it here for posterity:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

int main (int argc, char **argv)
{
    int fd, r;

    fd = open (argv[1], O_RDONLY);
    if (fd == -1) {
	fprintf (stderr, "Error: open %s: %s\n", argv[1], strerror (errno));
	exit (1);
    }

    r = fsync (fd);
    if (r)
	fprintf (stderr, "Error: fsync %s: %s\n", argv[1], strerror (errno));

    close (fd);

    return r;
}

[rfjakob]

Will FSYNCDIR be implemented?

Yes

[rfjakob]

Fixed, thanks for the report!

[ghost]

Do you think you can cut a release?

[rfjakob]

I want to fix a few more things before, but I can attach a build here if you want?

But as far as i saw in the notmuch code, the fsync message is just a warning, right?

[ghost]

Sure, I'll build it from source.
I don't think it was just a warning, notmuch operation aborted as soon as it hit fsync.