Copy-pasting reply from Joseph.
=============================================================================================
Hello Greogry,
We are setting the mtime to 01 Jan 1970 00:00
-
Create a directory "dir1"
-
set mtime of the "dir1 to 0 -> i.e 1 jan 1970
-
Create child directory in "dir1" i.e mkdir dir1/dir2 OR Create a file in "dir1" i.e "touch dir1/file1
-
stat "dir1"
Linux FS : updates the mtime of "dir1"
Ceph FS: DOESNOT update the mtime of "dir1"
Linux command output :
CEPHFS
===========================================================================
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# mkdir dir1
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# stat dir1
File: dir1
Size: 0 Blocks: 0 IO Block: 65536 directory
Device: 28h/40d Inode: 1099511714911 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2023-05-24 11:09:25.260851345 +0530
Modify: 2023-05-24 11:09:25.260851345 +0530
Change: 2023-05-24 11:09:25.260851345 +0530
Birth: 2023-05-24 11:09:25.260851345 +0530
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# touch -m -d '26 Aug 1982 22:00' dir1
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# stat dir1/
File: dir1/
Size: 0 Blocks: 0 IO Block: 65536 directory
Device: 28h/40d Inode: 1099511714911 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2023-05-24 11:09:25.260851345 +0530
Modify: 1982-08-26 22:00:00.000000000 +0530
Change: 2023-05-24 11:10:04.881454967 +0530
Birth: 2023-05-24 11:09:25.260851345 +0530
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# mkdir dir1/dir2
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538# stat dir1/
File: dir1/
Size: 1 Blocks: 0 IO Block: 65536 directory
Device: 28h/40d Inode: 1099511714911 Links: 3
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2023-05-24 11:09:25.260851345 +0530
Modify: 1982-08-26 22:00:00.000000000 +0530
Change: 2023-05-24 11:10:19.141672220 +0530
Birth: 2023-05-24 11:09:25.260851345 +0530
root@sds-ceph:/mnt/cephfs/volumes/_nogroup/test1/d5052b71-39ec-4d0a-9b0b-2091e1723538#
-Joe
=============================================================================================
Thanks and Regards
Sandip Divekar
From: Gregory Farnum <gfarnum@xxxxxxxxxx>
Sent: Thursday, May 25, 2023 8:43 PM
To: Sandip Divekar <sandip.divekar@xxxxxxxxxxxxxxxxxx>
Cc: Chris Palmer <chris.palmer@xxxxxxxxx>; Gavin Lucas <gavin.lucas@xxxxxxxxxxxxxxxxxx>; Joseph Fernandes <joseph.fernandes@xxxxxxxxxxxxxxxxxx>; Simon Crosland <Simon.Crosland@xxxxxxxxxxxxxxxxxx>; ceph-users@xxxxxxx; dev@xxxxxxx
Subject: Re: [ceph-users] Re: Unexpected behavior of directory mtime after being set explicitly
***** EXTERNAL EMAIL *****
I haven’t checked the logs, but the most obvious way this happens is if the mtime set on the directory is in the future compared to the time on the client or server making changes — CephFS does not move times backwards. (This causes some
problems but prevents many, many others when times are not synchronized well across the clients and servers.)
Hi Chris,
Kindly request you that follow steps given in previous mail and paste the output here.
The reason behind this request is that we have encountered an issue which is easily reproducible on
Latest version of both quincy and pacific, also we have thoroughly investigated the matter and we are certain that
No other factors are at play in this scenario.
Note : We have used Debian 11 for testing.
sdsadmin@ceph-pacific-1:~$ uname -a
Linux ceph-pacific-1 5.10.0-10-amd64 #1 SMP Debian 5.10.84-1 (2021-12-08) x86_64 GNU/Linux
sdsadmin@ceph-pacific-1:~$ sudo ceph -v
ceph version 16.2.13 (5378749ba6be3a0868b51803968ee9cde4833a3e) pacific (stable)
Thanks for your prompt reply.
Regards
Sandip Divekar
-----Original Message-----
From: Chris Palmer <chris.palmer@xxxxxxxxx>
Sent: Thursday, May 25, 2023 7:25 PM
To: ceph-users@xxxxxxx
Subject: [ceph-users] Re: Unexpected behavior of directory mtime after being set explicitly
***** EXTERNAL EMAIL *****
Hi Milind
I just tried this using the ceph kernel client and ceph-common 17.2.6 package in the latest Fedora kernel, against Ceph 17.2.6 and it worked perfectly...
There must be some other factor in play.
Chris
On 25/05/2023 13:04, Sandip Divekar wrote:
> Hello Milind,
>
> We are using Ceph Kernel Client.
> But we found this same behavior while using Libcephfs library.
>
> Should we treat this as a bug? Or
> Is there any existing bug for similar issue ?
>
> Thanks and Regards,
> Sandip Divekar
>
>
> From: Milind Changire <mchangir@xxxxxxxxxx>
> Sent: Thursday, May 25, 2023 4:24 PM
> To: Sandip Divekar <sandip.divekar@xxxxxxxxxxxxxxxxxx>
> Cc: ceph-users@xxxxxxx;
dev@xxxxxxx
> Subject: Re: [ceph-users] Unexpected behavior of directory mtime after
> being set explicitly
>
> ***** EXTERNAL EMAIL *****
> Sandip,
> What type of client are you using ?
> kernel client or fuse client ?
>
> If it's the kernel client, then it's a bug.
>
> FYI - Pacific and Quincy fuse clients do the right thing
>
>
> On Wed, May 24, 2023 at 9:24 PM Sandip Divekar <sandip.divekar@xxxxxxxxxxxxxxxxxx<mailto:sandip.divekar@xxxxxxxxxxxxxxxxxx>>
wrote:
> Hi Team,
>
> I'm writing to bring to your attention an issue we have encountered with the "mtime" (modification time) behavior for directories in the Ceph filesystem.
>
> Upon observation, we have noticed that when the mtime of a directory
> (let's say: dir1) is explicitly changed in CephFS, subsequent additions of files or directories within 'dir1' fail to update the directory's mtime as expected.
>
> This behavior appears to be specific to CephFS - we have reproduced this issue on both Quincy and Pacific. Similar steps work as expected in the ext4 filesystem amongst others.
>
> Reproduction steps:
> 1. Create a directory - mkdir dir1
> 2. Modify mtime using the touch command - touch dir1 3. Create a file
> or directory inside of 'dir1' - mkdir dir1/dir2 Expected result:
> mtime for dir1 should change to the time the file or directory was
> created in step 3 Actual result:
> there was no change to the mtime for 'dir1'
>
> Note : For more detail, kindly find the attached logs.
>
> Our queries are :
> 1. Is this expected behavior for CephFS?
> 2. If so, can you explain why the directory behavior is inconsistent depending on whether the mtime for the directory has previously been manually updated.
>
>
> Best Regards,
> Sandip Divekar
> Component QA Lead SDET.
>
> _______________________________________________
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>
> --
> Milind
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