[OT] Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-10-01 Thread Gabriel Paubert
On Sat, Sep 30, 2023 at 09:50:41AM -0500, Steve French wrote: > On Fri, Sep 29, 2023 at 3:06 AM David Howells via samba-technical > wrote: > > > > > > Jeff Layton wrote: > > > > > Correct. We'd lose some fidelity in currently stored timestamps, but as > > > Linus and Ted pointed out, anything

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-30 Thread Steve French
On Fri, Sep 29, 2023 at 3:06 AM David Howells via samba-technical wrote: > > > Jeff Layton wrote: > > > Correct. We'd lose some fidelity in currently stored timestamps, but as > > Linus and Ted pointed out, anything below ~100ns granularity is > > effectively just noise, as that's the floor

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-29 Thread Linus Torvalds
On Thu, 28 Sept 2023 at 20:50, Amir Goldstein wrote: > > OTOH, it is perfectly fine if the vfs wants to stop providing sub 100ns > services to filesystems. It's just going to be the fs problem and the > preserved pre-historic/fine-grained time on existing files would only > need to be provided in

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-29 Thread Jeff Layton
On Fri, 2023-09-29 at 11:44 +0200, Christian Brauner wrote: > > It is a lot of churn though. > > I think that i_{a,c,m}time shouldn't be accessed directly by > filesystems same as no filesystem should really access i_{g,u}id which > we also provide i_{g,u}id_{read,write}() accessors for. The mode

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-29 Thread Christian Brauner
> It is a lot of churn though. I think that i_{a,c,m}time shouldn't be accessed directly by filesystems same as no filesystem should really access i_{g,u}id which we also provide i_{g,u}id_{read,write}() accessors for. The mode is another example where really most often should use helpers because

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-29 Thread David Howells
Jeff Layton wrote: > Correct. We'd lose some fidelity in currently stored timestamps, but as > Linus and Ted pointed out, anything below ~100ns granularity is > effectively just noise, as that's the floor overhead for calling into > the kernel. It's hard to argue that any application needs

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Amir Goldstein
On Fri, Sep 29, 2023 at 3:19 AM Linus Torvalds wrote: ... > So yes, real programs to cache stat information, and it matters for > performance. > > But I don't think any actual reasonable program will have > *correctness* issues, though - I beg to disagree. > because there are certainly

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Amir Goldstein
On Thu, Sep 28, 2023 at 8:19 PM Darrick J. Wong wrote: > > On Thu, Sep 28, 2023 at 01:06:03PM -0400, Jeff Layton wrote: > > On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > > > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > > > This shaves 8 bytes off struct inode, according to

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Linus Torvalds
On Thu, 28 Sept 2023 at 14:28, Theodore Ts'o wrote: > > I don't think anyone will complain about breaking the userspace API > --- especially since if, say, the CIA was using this for their spies' > drop boxes, they probably wouldn't want to admit it. :-) Well, you will find that real apps do

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Theodore Ts'o
On Thu, Sep 28, 2023 at 01:40:55PM -0400, Jeff Layton wrote: > > Correct. We'd lose some fidelity in currently stored timestamps, but as > Linus and Ted pointed out, anything below ~100ns granularity is > effectively just noise, as that's the floor overhead for calling into > the kernel. It's

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Arnd Bergmann
On Thu, Sep 28, 2023, at 13:40, Jeff Layton wrote: > On Thu, 2023-09-28 at 10:19 -0700, Darrick J. Wong wrote: >> >> > I remember seeing those patches go by. I don't remember that change >> > being NaK'ed, but I wasn't paying close attention at the time >> > >> > Looking at it objectively now, I

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Jeff Layton
On Thu, 2023-09-28 at 10:19 -0700, Darrick J. Wong wrote: > On Thu, Sep 28, 2023 at 01:06:03PM -0400, Jeff Layton wrote: > > On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > > > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > > > This shaves 8 bytes off struct inode, according to

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Darrick J. Wong
On Thu, Sep 28, 2023 at 01:06:03PM -0400, Jeff Layton wrote: > On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > > This shaves 8 bytes off struct inode, according to pahole. > > > > > > Signed-off-by: Jeff Layton > > > > FWIW,

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Jeff Layton
On Thu, 2023-09-28 at 07:05 -0400, Jeff Layton wrote: > This shaves 8 bytes off struct inode, according to pahole. > > Signed-off-by: Jeff Layton > --- > include/linux/fs.h | 32 +++- > 1 file changed, 23 insertions(+), 9 deletions(-) > > diff --git

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Jeff Layton
On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > This shaves 8 bytes off struct inode, according to pahole. > > > > Signed-off-by: Jeff Layton > > FWIW, this is similar to the approach that Deepa suggested > back in 2016: > >

Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Arnd Bergmann
On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > This shaves 8 bytes off struct inode, according to pahole. > > Signed-off-by: Jeff Layton FWIW, this is similar to the approach that Deepa suggested back in 2016:

[PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

2023-09-28 Thread Jeff Layton
This shaves 8 bytes off struct inode, according to pahole. Signed-off-by: Jeff Layton --- include/linux/fs.h | 32 +++- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 831657011036..de902ff2938b 100644 ---