2019-06-27 13:51:51

by Luis Henriques

[permalink] [raw]
Subject: [RFC PATCH] ceph: initialize superblock s_time_gran to 1

Having granularity set to 1us results in having inode timestamps with a
accurancy different from the fuse client (i.e. atime, ctime and mtime will
always end with '000'). This patch normalizes this behaviour and sets the
granularity to 1.

Signed-off-by: Luis Henriques <[email protected]>
---
fs/ceph/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Hi!

As far as I could see there are no other side-effects of changing
s_time_gran but I'm really not sure why it was initially set to 1000 in
the first place so I may be missing something.

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index d57fa60dcd43..35dd75bc9cd0 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
s->s_d_op = &ceph_dentry_ops;
s->s_export_op = &ceph_export_ops;

- s->s_time_gran = 1000; /* 1000 ns == 1 us */
+ s->s_time_gran = 1;

ret = set_anon_super(s, NULL); /* what is that second arg for? */
if (ret != 0)


2019-06-27 14:42:24

by Jeffrey Layton

[permalink] [raw]
Subject: Re: [RFC PATCH] ceph: initialize superblock s_time_gran to 1

On Thu, 2019-06-27 at 14:51 +0100, Luis Henriques wrote:
> Having granularity set to 1us results in having inode timestamps with a
> accurancy different from the fuse client (i.e. atime, ctime and mtime will
> always end with '000'). This patch normalizes this behaviour and sets the
> granularity to 1.
>
> Signed-off-by: Luis Henriques <[email protected]>
> ---
> fs/ceph/super.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Hi!
>
> As far as I could see there are no other side-effects of changing
> s_time_gran but I'm really not sure why it was initially set to 1000 in
> the first place so I may be missing something.
>
> diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> index d57fa60dcd43..35dd75bc9cd0 100644
> --- a/fs/ceph/super.c
> +++ b/fs/ceph/super.c
> @@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
> s->s_d_op = &ceph_dentry_ops;
> s->s_export_op = &ceph_export_ops;
>
> - s->s_time_gran = 1000; /* 1000 ns == 1 us */
> + s->s_time_gran = 1;
>
> ret = set_anon_super(s, NULL); /* what is that second arg for? */
> if (ret != 0)


Looks like it was set that way since the client code was originally
merged. Was this an earlier limitation of ceph that is no longer
applicable?

In any case, I see no need at all to keep this at 1000, so:

Reviewed-by: Jeff Layton <[email protected]>

2019-06-27 15:45:46

by Sage Weil

[permalink] [raw]
Subject: Re: [RFC PATCH] ceph: initialize superblock s_time_gran to 1

On Thu, 27 Jun 2019, Jeff Layton wrote:
> On Thu, 2019-06-27 at 14:51 +0100, Luis Henriques wrote:
> > Having granularity set to 1us results in having inode timestamps with a
> > accurancy different from the fuse client (i.e. atime, ctime and mtime will
> > always end with '000'). This patch normalizes this behaviour and sets the
> > granularity to 1.
> >
> > Signed-off-by: Luis Henriques <[email protected]>
> > ---
> > fs/ceph/super.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Hi!
> >
> > As far as I could see there are no other side-effects of changing
> > s_time_gran but I'm really not sure why it was initially set to 1000 in
> > the first place so I may be missing something.
> >
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index d57fa60dcd43..35dd75bc9cd0 100644
> > --- a/fs/ceph/super.c
> > +++ b/fs/ceph/super.c
> > @@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
> > s->s_d_op = &ceph_dentry_ops;
> > s->s_export_op = &ceph_export_ops;
> >
> > - s->s_time_gran = 1000; /* 1000 ns == 1 us */
> > + s->s_time_gran = 1;
> >
> > ret = set_anon_super(s, NULL); /* what is that second arg for? */
> > if (ret != 0)
>
>
> Looks like it was set that way since the client code was originally
> merged. Was this an earlier limitation of ceph that is no longer
> applicable?
>
> In any case, I see no need at all to keep this at 1000, so:

As long as the encoded on-write time value is at ns resolution, I
agree! No recollection of why I did this :(

Reviewed-by: Sage Weil <[email protected]>

2019-06-27 16:11:01

by Jeffrey Layton

[permalink] [raw]
Subject: Re: [RFC PATCH] ceph: initialize superblock s_time_gran to 1

On Thu, 2019-06-27 at 15:44 +0000, Sage Weil wrote:
> On Thu, 27 Jun 2019, Jeff Layton wrote:
> > On Thu, 2019-06-27 at 14:51 +0100, Luis Henriques wrote:
> > > Having granularity set to 1us results in having inode timestamps with a
> > > accurancy different from the fuse client (i.e. atime, ctime and mtime will
> > > always end with '000'). This patch normalizes this behaviour and sets the
> > > granularity to 1.
> > >
> > > Signed-off-by: Luis Henriques <[email protected]>
> > > ---
> > > fs/ceph/super.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > Hi!
> > >
> > > As far as I could see there are no other side-effects of changing
> > > s_time_gran but I'm really not sure why it was initially set to 1000 in
> > > the first place so I may be missing something.
> > >
> > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > > index d57fa60dcd43..35dd75bc9cd0 100644
> > > --- a/fs/ceph/super.c
> > > +++ b/fs/ceph/super.c
> > > @@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
> > > s->s_d_op = &ceph_dentry_ops;
> > > s->s_export_op = &ceph_export_ops;
> > >
> > > - s->s_time_gran = 1000; /* 1000 ns == 1 us */
> > > + s->s_time_gran = 1;
> > >
> > > ret = set_anon_super(s, NULL); /* what is that second arg for? */
> > > if (ret != 0)
> >
> >
> > Looks like it was set that way since the client code was originally
> > merged. Was this an earlier limitation of ceph that is no longer
> > applicable?
> >
> > In any case, I see no need at all to keep this at 1000, so:
>
> As long as the encoded on-write time value is at ns resolution, I
> agree! No recollection of why I did this :(
>
> Reviewed-by: Sage Weil <[email protected]>

Good enough for me. I went ahead and merged this into the testing
branch. Assuming nothing breaks, this should make v5.3.

Thanks,
--
Jeff Layton <[email protected]>

2019-06-28 09:31:20

by Luis Henriques

[permalink] [raw]
Subject: Re: [RFC PATCH] ceph: initialize superblock s_time_gran to 1

Jeff Layton <[email protected]> writes:

> On Thu, 2019-06-27 at 15:44 +0000, Sage Weil wrote:
>> On Thu, 27 Jun 2019, Jeff Layton wrote:
>> > On Thu, 2019-06-27 at 14:51 +0100, Luis Henriques wrote:
>> > > Having granularity set to 1us results in having inode timestamps with a
>> > > accurancy different from the fuse client (i.e. atime, ctime and mtime will
>> > > always end with '000'). This patch normalizes this behaviour and sets the
>> > > granularity to 1.
>> > >
>> > > Signed-off-by: Luis Henriques <[email protected]>
>> > > ---
>> > > fs/ceph/super.c | 2 +-
>> > > 1 file changed, 1 insertion(+), 1 deletion(-)
>> > >
>> > > Hi!
>> > >
>> > > As far as I could see there are no other side-effects of changing
>> > > s_time_gran but I'm really not sure why it was initially set to 1000 in
>> > > the first place so I may be missing something.
>> > >
>> > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
>> > > index d57fa60dcd43..35dd75bc9cd0 100644
>> > > --- a/fs/ceph/super.c
>> > > +++ b/fs/ceph/super.c
>> > > @@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
>> > > s->s_d_op = &ceph_dentry_ops;
>> > > s->s_export_op = &ceph_export_ops;
>> > >
>> > > - s->s_time_gran = 1000; /* 1000 ns == 1 us */
>> > > + s->s_time_gran = 1;
>> > >
>> > > ret = set_anon_super(s, NULL); /* what is that second arg for? */
>> > > if (ret != 0)
>> >
>> >
>> > Looks like it was set that way since the client code was originally
>> > merged. Was this an earlier limitation of ceph that is no longer
>> > applicable?
>> >
>> > In any case, I see no need at all to keep this at 1000, so:
>>
>> As long as the encoded on-write time value is at ns resolution, I
>> agree! No recollection of why I did this :(
>>
>> Reviewed-by: Sage Weil <[email protected]>
>
> Good enough for me. I went ahead and merged this into the testing
> branch. Assuming nothing breaks, this should make v5.3.

Awesome, thanks. AFAICS it shouldn't break anything, specially because
the fuse client seems to be using ns resolution too. But yeah
unexpected side-effects show up in unexpected ways :-)

Cheers,
--
Luis