[PATCH] ksmbd: set create_time to btime in ksmbd_vfs_fill_dentry_attrs()

[PATCH] ksmbd: set create_time to btime in ksmbd_vfs_fill_dentry_attrs()

[koraynilay]

ksmbd_vfs_fill_dentry_attrs() queries vfs_getattr() with STATX_BTIME,
but discards ksmbd_kstat->kstat->btime and unconditionally initializes
ksmbd_kstat->create_time to ksmbd_kstat->kstat->ctime.

Check ksmbd_kstat->kstat->result_mask for STATX_BTIME and set
ksmbd_kstat->create_time to ksmbd_kstat->kstat->btime, only falling back
to ctime if btime isn't returned, matching the existing behavior in
smb2_open().

Fixes: 5614c8c487f6 ("ksmbd: replace generic_fillattr with vfs_getattr")
Cc: stable@vger.kernel.org
Assisted-by: Gemini:3.8-flash-high antigravity-cli-1.5.3
Signed-off-by: koraynilay <koray.fra@gmail.com>
---
Small fix I found while implementing ptime[1].
Thanks.

[1]: https://lore.kernel.org/all/20261101015551.786044-1-koray.fra@gmail.com/T/#t

 fs/smb/server/vfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index cb3f4f5fe9cf..0c95d4668370 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -1914,7 +1914,10 @@ int ksmbd_vfs_fill_dentry_attrs(struct ksmbd_work *work,
 	if (rc)
 		return rc;
 
-	time = ksmbd_UnixTimeToNT(ksmbd_kstat->kstat->ctime);
+	if (ksmbd_kstat->kstat->result_mask & STATX_BTIME)
+		time = ksmbd_UnixTimeToNT(ksmbd_kstat->kstat->btime);
+	else
+		time = ksmbd_UnixTimeToNT(ksmbd_kstat->kstat->ctime);
 	ksmbd_kstat->create_time = time;
 
 	/*

base-commit: b0af9a3e6b1534d353ca6ac23caaf46127f62e4a
-- 
2.56.0

Re: [PATCH] ksmbd: set create_time to btime in ksmbd_vfs_fill_dentry_attrs()

[Ian Bridges]

Hi,

On Tue, Nov 10, 2026 at 05:16:59PM +0100, koraynilay wrote:
> ksmbd_vfs_fill_dentry_attrs() queries vfs_getattr() with STATX_BTIME,
> but discards ksmbd_kstat->kstat->btime and unconditionally initializes
> ksmbd_kstat->create_time to ksmbd_kstat->kstat->ctime.

I tested this on a kernel whose fs/smb/server matches ksmbd-for-next,
with files and a directory created on the server, so without the DOS
attribute xattr. Before the patch, a directory listing reported their
ctime as the creation time, while a query on the open file reported
the btime. With the patch, both report the btime. A file created over
SMB keeps its stored creation time in both. smbtorture gives the same
results as without the patch, and KASAN reports nothing.

Reviewed-by: Ian Bridges <icb@fastmail.org>
Tested-by: Ian Bridges <icb@fastmail.org>

Re: [PATCH] ksmbd: set create_time to btime in ksmbd_vfs_fill_dentry_attrs()

[Namjae Jeon]

On Wed, Nov 11, 2026 at 4:56 AM Ian Bridges <icb@fastmail.org> wrote:
>
> Hi,
>
> On Tue, Nov 10, 2026 at 05:16:59PM +0100, koraynilay wrote:
> > ksmbd_vfs_fill_dentry_attrs() queries vfs_getattr() with STATX_BTIME,
> > but discards ksmbd_kstat->kstat->btime and unconditionally initializes
> > ksmbd_kstat->create_time to ksmbd_kstat->kstat->ctime.
>
> I tested this on a kernel whose fs/smb/server matches ksmbd-for-next,
> with files and a directory created on the server, so without the DOS
> attribute xattr. Before the patch, a directory listing reported their
> ctime as the creation time, while a query on the open file reported
> the btime. With the patch, both report the btime. A file created over
> SMB keeps its stored creation time in both. smbtorture gives the same
> results as without the patch, and KASAN reports nothing.
>
> Reviewed-by: Ian Bridges <icb@fastmail.org>
> Tested-by: Ian Bridges <icb@fastmail.org>
Applied this patch to #ksmbd-for-next.
Thanks!

Re: [PATCH] ksmbd: set create_time to btime in ksmbd_vfs_fill_dentry_attrs()

[koraynilay]

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On Tue Nov 10, 2026 at 11:45 PM CET, Namjae Jeon wrote:
> On Wed, Nov 11, 2026 at 4:56 AM Ian Bridges <icb@fastmail.org> wrote:
>>
>> Hi,
>>
>> On Tue, Nov 10, 2026 at 05:16:59PM +0100, koraynilay wrote:
>> > ksmbd_vfs_fill_dentry_attrs() queries vfs_getattr() with STATX_BTIME,
>> > but discards ksmbd_kstat->kstat->btime and unconditionally initializes
>> > ksmbd_kstat->create_time to ksmbd_kstat->kstat->ctime.
>>
>> I tested this on a kernel whose fs/smb/server matches ksmbd-for-next,
>> with files and a directory created on the server, so without the DOS
>> attribute xattr. Before the patch, a directory listing reported their
>> ctime as the creation time, while a query on the open file reported
>> the btime. With the patch, both report the btime. A file created over
>> SMB keeps its stored creation time in both. smbtorture gives the same
>> results as without the patch, and KASAN reports nothing.
>>
>> Reviewed-by: Ian Bridges <icb@fastmail.org>
>> Tested-by: Ian Bridges <icb@fastmail.org>
> Applied this patch to #ksmbd-for-next.
> Thanks!

Thanks!

Best,
koraynilay

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