New: directory ctime not updated by rename

http://bugzilla.kernel.org/show_bug.cgi?id=10276

Summary: directory ctime not updated by rename
Product: File System
Version: 2.5
KernelVersion: 2.6.24.3
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: ext3
AssignedTo: [email protected]
ReportedBy: [email protected]

Latest working kernel version:
Earliest failing kernel version:
Distribution: LFS
Hardware Environment: 32bit x86
Software Environment:
Problem Description: Renaming a file into a directory so that an already existing file is overwritten, will not update the ctime on the directory. This seems to be the reason for certain failures with incremental backups (e.g., with star).

Steps to reproduce:

Run the following commands and watch the output from stat. Upon the second run of rename, the ctime is not updated on the directory sub.

rm -fr sub new &&
mkdir sub &&
stat sub &&
sleep 2 &&
echo running rename &&
./rename a &&
stat sub &&
sleep 2 &&
echo running rename again &&
./rename b &&
stat sub

Here is rename.c:

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

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

        fd = open("new", O_WRONLY | O_NDELAY | O_TRUNC | O_CREAT, 0644);        
        write(fd, argv[1], 1);
        close(fd);
        rename("new", "sub/x");

        return 0;
}

Do we agree that this is a bug? If so, is it a VFS thing or a per-fs thing?

Quoted 2 lines · Andrew Morton

Do we agree that this is a bug? If so, is it a VFS thing or a per-fs thing?

The latter; all control over timestamps on directory operations is in filesystems. Which filesystem it is, BTW? E.g. ext2 has

Quoted 2 lines · Andrew Morton

Do we agree that this is a bug? If so, is it a VFS thing or a per-fs thing?

The latter; all control over timestamps on directory operations is in filesystems.

Which filesystem it is, BTW?

E.g. ext2 has

        dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;

in ext2_set_link() (and the same in ext2_add_entry()/ext2_delete_entry()), so on all paths in ext2_rename() both parents will get ctime and mtime updated; so will the object being moved and the object being unlinked (explicitly in ext2_rename()).

The latter; all control over timestamps on directory operations is in filesystems. Which filesystem it is, BTW? E.g. ext2 has

        dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;

in ext2_set_link() (and the same in ext2_add_entry()/ext2_delete_entry()), so on all paths in ext2_rename() both parents will get ctime and mtime updated; so will the object being moved and the object being unlinked (explicitly in ext2_rename()).