Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

[Andrew Morton]

On Tue, 18 Mar 2008 09:11:54 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

> 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: akpm@osdl.org
>         ReportedBy: lasse-kernelbug-2008@mail.plastictree.net
> 
> 
> 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?

Thanks.

Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

[Al Viro]

On Tue, Mar 18, 2008 at 10:00:23AM -0700, Andrew Morton wrote:

> 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()).

Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

[Al Viro]

On Tue, Mar 18, 2008 at 05:46:09PM +0000, Al Viro wrote:
> On Tue, Mar 18, 2008 at 10:00:23AM -0700, Andrew Morton wrote:
> 
> > 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

Doh.  ext3...  OK, that's a bug; direct update of directory entry by
                new_de->inode = cpu_to_le32(old_inode->i_ino);
needs an update of timestamps of new_dir.

Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

[Andrew Morton]

On Tue, 18 Mar 2008 17:46:09 +0000 Al Viro <viro@ZenIV.linux.org.uk> wrote:

> On Tue, Mar 18, 2008 at 10:00:23AM -0700, Andrew Morton wrote:
> 
> > 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.

OK

>  Which filesystem it is, BTW?

ext3.

>  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()).

Re: [Bugme-new] [Bug 10276] New: directory ctime not updated by rename

[hooanon05]

Al Viro:
> 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()).

Is it correct to update the mtime of renaming inode?
When it is a regular file the mtime is not updated, but a directory. I
have been wondering it for a long time.

$ stat -f .
  File: "."
    ID: c39e8aabce296ceb Namelen: 255     Type: ext2/ext3
Block size: 1024       Fundamental block size: 1024
Blocks: Total: 124442     Free: 122443     Available: 116018
Inodes: Total: 32256      Free: 32144
(actually it is ext2)

$ mkdir d1
$ stat d1
  File: `d1'
  Size: 1024      	Blocks: 2          IO Block: 1024   directory
Device: 30ah/778d	Inode: 2017        Links: 2
Access: (0755/drwxr-xr-x)  Uid: ( 1000/     jro)   Gid: ( 1000/     jro)
Access: 2008-03-20 12:33:57.000000000 +0900
Modify: 2008-03-20 12:33:57.000000000 +0900
Change: 2008-03-20 12:33:57.000000000 +0900

$ /tmp/rename d1 d2
(simply issues rename systemcall.)

$ stat d2
  File: `d2'
  Size: 1024      	Blocks: 2          IO Block: 1024   directory
Device: 30ah/778d	Inode: 2017        Links: 2
Access: (0755/drwxr-xr-x)  Uid: ( 1000/     jro)   Gid: ( 1000/     jro)
Access: 2008-03-20 12:33:57.000000000 +0900
Modify: 2008-03-20 12:34:11.000000000 +0900
Change: 2008-03-20 12:34:11.000000000 +0900
$ 


Junjiro Okajima