[PATCH] libf2fs: Fix calculation of usable segments for single zoned

[PATCH] libf2fs: Fix calculation of usable segments for single zoned

[Yonggil Song]

There was a bug that did not subtract the super block area when calculating
the usable segments for a single zoned device with a conventional zone.
This bug resulted in incorrect the overprovision and reserved area.

	<256MiB legacy block + zoned block w/ 32MiB zone size>
	Info: Overprovision ratio = 3.570%
	Info: Overprovision segments = 656 (GC reserved = 560)

	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
	Info: Overprovision ratio = 3.700%
	Info: Overprovision segments = 676 (GC reserved = 578)

This patch fixes the bug by subtracting the super block area when there is
only one zoned device.

Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
---
 lib/libf2fs_zoned.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
index 89ba5ad73a76..cc5c064b7e3e 100644
--- a/lib/libf2fs_zoned.c
+++ b/lib/libf2fs_zoned.c
@@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
 	}
 	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
 						get_sb(log_blocks_per_seg);
+
+	/* single zoned device needs to remove a super block area */
+	if (c.ndevs == 1)
+		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));
+
 	return usable_segs;
 #endif
 	return get_sb(segment_count_main);
-- 
2.43.0

Re: [PATCH] libf2fs: Fix calculation of usable segments for single zoned

[Chao Yu]

On 2024/10/7 13:21, Yonggil Song wrote:
> There was a bug that did not subtract the super block area when calculating
> the usable segments for a single zoned device with a conventional zone.
> This bug resulted in incorrect the overprovision and reserved area.
> 
> 	<256MiB legacy block + zoned block w/ 32MiB zone size>
> 	Info: Overprovision ratio = 3.570%
> 	Info: Overprovision segments = 656 (GC reserved = 560)
> 
> 	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
> 	Info: Overprovision ratio = 3.700%
> 	Info: Overprovision segments = 676 (GC reserved = 578)
> 
> This patch fixes the bug by subtracting the super block area when there is
> only one zoned device.
> 
> Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
> ---
>   lib/libf2fs_zoned.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
> index 89ba5ad73a76..cc5c064b7e3e 100644
> --- a/lib/libf2fs_zoned.c
> +++ b/lib/libf2fs_zoned.c
> @@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
>   	}
>   	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
>   						get_sb(log_blocks_per_seg);
> +
> +	/* single zoned device needs to remove a super block area */

If we don't format zoned device, it doesn't need to do this?

Thanks,

> +	if (c.ndevs == 1)
 > +		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));> +
>   	return usable_segs;
>   #endif
>   	return get_sb(segment_count_main);

RE:(2) [PATCH] libf2fs: Fix calculation of usable segments for single zoned

[Yonggil Song]

> On 2024/10/7 13:21, Yonggil Song wrote:
> > There was a bug that did not subtract the super block area when calculating
> > the usable segments for a single zoned device with a conventional zone.
> > This bug resulted in incorrect the overprovision and reserved area.
> > 
> > 	<256MiB legacy block + zoned block w/ 32MiB zone size>
> > 	Info: Overprovision ratio = 3.570%
> > 	Info: Overprovision segments = 656 (GC reserved = 560)
> > 
> > 	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
> > 	Info: Overprovision ratio = 3.700%
> > 	Info: Overprovision segments = 676 (GC reserved = 578)
> > 
> > This patch fixes the bug by subtracting the super block area when there is
> > only one zoned device.
> > 
> > Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
> > ---
> >   lib/libf2fs_zoned.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> > 
> > diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
> > index 89ba5ad73a76..cc5c064b7e3e 100644
> > --- a/lib/libf2fs_zoned.c
> > +++ b/lib/libf2fs_zoned.c
> > @@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
> >   	}
> >   	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
> >   						get_sb(log_blocks_per_seg);
> > +
> > +	/* single zoned device needs to remove a super block area */
> 
> If we don't format zoned device, it doesn't need to do this?
> 
> Thanks,
> 
Yes, single zoned block only needs this.

legacy block just return a segment_count_main.

thanks.
> > +	if (c.ndevs == 1)
>  > +		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));> +
> >   	return usable_segs;
> >   #endif
> >   	return get_sb(segment_count_main);

RE:(3) [PATCH] libf2fs: Fix calculation of usable segments for single zoned

[Yonggil Song]

> > On 2024/10/7 13:21, Yonggil Song wrote:
> > > There was a bug that did not subtract the super block area when calculating
> > > the usable segments for a single zoned device with a conventional zone.
> > > This bug resulted in incorrect the overprovision and reserved area.
> > > 
> > > 	<256MiB legacy block + zoned block w/ 32MiB zone size>
> > > 	Info: Overprovision ratio = 3.570%
> > > 	Info: Overprovision segments = 656 (GC reserved = 560)
> > > 
> > > 	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
> > > 	Info: Overprovision ratio = 3.700%
> > > 	Info: Overprovision segments = 676 (GC reserved = 578)
> > > 
> > > This patch fixes the bug by subtracting the super block area when there is
> > > only one zoned device.
> > > 
> > > Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
> > > ---
> > >   lib/libf2fs_zoned.c | 5 +++++
> > >   1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
> > > index 89ba5ad73a76..cc5c064b7e3e 100644
> > > --- a/lib/libf2fs_zoned.c
> > > +++ b/lib/libf2fs_zoned.c
> > > @@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
> > >   	}
> > >   	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
> > >   						get_sb(log_blocks_per_seg);
> > > +
> > > +	/* single zoned device needs to remove a super block area */
> > 
> > If we don't format zoned device, it doesn't need to do this?
> > 
> > Thanks,
> > 
> Yes, single zoned block only needs this.
> 
> legacy block just return a segment_count_main.
> 
> thanks.
Sorry, I misunderstood.
I'll resend v2 with zoned block checker.

thanks.
> > > +	if (c.ndevs == 1)
> >  > +		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));> +
> > >   	return usable_segs;
> > >   #endif
> > >   	return get_sb(segment_count_main);

[PATCH v2] libf2fs: Fix calculation of usable segments for single

[Yonggil Song]

There was a problem that did not subtract the super block area when calculating
the usable segments for a single zoned device with a conventional zone.
This resulted in incorrect the overprovision and reserved area.

	<256MiB legacy block + zoned block w/ 32MiB zone size>
	Info: Overprovision ratio = 3.570%
	Info: Overprovision segments = 656 (GC reserved = 560)

	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
	Info: Overprovision ratio = 3.700%
	Info: Overprovision segments = 676 (GC reserved = 578)

This patch addresses the problem by subtracting the super block area when
there is only one zoned device.

Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
---
 lib/libf2fs_zoned.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
index 89ba5ad73a76..1a0985378789 100644
--- a/lib/libf2fs_zoned.c
+++ b/lib/libf2fs_zoned.c
@@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
 	}
 	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
 						get_sb(log_blocks_per_seg);
+
+	/* single zoned device needs to remove a super block area */
+	if (c.ndevs == 1 && c.devices[0].zoned_model == F2FS_ZONED_HM)
+		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));
+
 	return usable_segs;
 #endif
 	return get_sb(segment_count_main);
-- 
2.43.0

[RESEND][PATCH v2] libf2fs: Fix calculation of usable segments for single zoned device

[Yonggil Song]

There was a problem that did not subtract the super block area when calculating
the usable segments for a single zoned device with a conventional zone.
This resulted in incorrect the overprovision and reserved area.

	<256MiB legacy block + zoned block w/ 32MiB zone size>
	Info: Overprovision ratio = 3.570%
	Info: Overprovision segments = 656 (GC reserved = 560)

	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
	Info: Overprovision ratio = 3.700%
	Info: Overprovision segments = 676 (GC reserved = 578)

This patch addresses the problem by subtracting the super block area when
there is only one zoned device.

Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
---
 lib/libf2fs_zoned.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
index 89ba5ad73a76..1a0985378789 100644
--- a/lib/libf2fs_zoned.c
+++ b/lib/libf2fs_zoned.c
@@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
 	}
 	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
 						get_sb(log_blocks_per_seg);
+
+	/* single zoned device needs to remove a super block area */
+	if (c.ndevs == 1 && c.devices[0].zoned_model == F2FS_ZONED_HM)
+		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));
+
 	return usable_segs;
 #endif
 	return get_sb(segment_count_main);
-- 
2.43.0

Re: [PATCH v2] libf2fs: Fix calculation of usable segments for single

[Jaegeuk Kim]

On 10/10, Yonggil Song wrote:
> There was a problem that did not subtract the super block area when calculating
> the usable segments for a single zoned device with a conventional zone.
> This resulted in incorrect the overprovision and reserved area.
> 
> 	<256MiB legacy block + zoned block w/ 32MiB zone size>
> 	Info: Overprovision ratio = 3.570%
> 	Info: Overprovision segments = 656 (GC reserved = 560)
> 
> 	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
> 	Info: Overprovision ratio = 3.700%
> 	Info: Overprovision segments = 676 (GC reserved = 578)
> 
> This patch addresses the problem by subtracting the super block area when
> there is only one zoned device.
> 
> Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
> ---
>  lib/libf2fs_zoned.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
> index 89ba5ad73a76..1a0985378789 100644
> --- a/lib/libf2fs_zoned.c
> +++ b/lib/libf2fs_zoned.c
> @@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
>  	}
>  	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
>  						get_sb(log_blocks_per_seg);
> +
> +	/* single zoned device needs to remove a super block area */
> +	if (c.ndevs == 1 && c.devices[0].zoned_model == F2FS_ZONED_HM)

Does this work?

> +		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));
> +
>  	return usable_segs;
>  #endif
>  	return get_sb(segment_count_main);
> -- 
> 2.43.0

RE:(2) [PATCH v2] libf2fs: Fix calculation of usable segments for single

[Yonggil Song]

> On 10/10, Yonggil Song wrote:
> > There was a problem that did not subtract the super block area when calculating
> > the usable segments for a single zoned device with a conventional zone.
> > This resulted in incorrect the overprovision and reserved area.
> > 
> > 	<256MiB legacy block + zoned block w/ 32MiB zone size>
> > 	Info: Overprovision ratio = 3.570%
> > 	Info: Overprovision segments = 656 (GC reserved = 560)
> > 
> > 	<8 conventional zone + 1016 sequential zone w/ 32MiB zone size>
> > 	Info: Overprovision ratio = 3.700%
> > 	Info: Overprovision segments = 676 (GC reserved = 578)
> > 
> > This patch addresses the problem by subtracting the super block area when
> > there is only one zoned device.
> > 
> > Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
> > ---
> >  lib/libf2fs_zoned.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
> > index 89ba5ad73a76..1a0985378789 100644
> > --- a/lib/libf2fs_zoned.c
> > +++ b/lib/libf2fs_zoned.c
> > @@ -555,6 +555,11 @@ uint32_t f2fs_get_usable_segments(struct f2fs_super_block *sb)
> >  	}
> >  	usable_segs -= (get_sb(main_blkaddr) - get_sb(segment0_blkaddr)) >>
> >  						get_sb(log_blocks_per_seg);
> > +
> > +	/* single zoned device needs to remove a super block area */
> > +	if (c.ndevs == 1 && c.devices[0].zoned_model == F2FS_ZONED_HM)
> 
> Does this work?
> 
Yes, it works.

I have attached the results of test on null_blk below.
If you have any concerns, please feedback.

						before				after
legacy block (32GB)				136 (GC reserved = 130)		136 (GC reserved = 130)
single zoned block				676 (GC reserved = 578)		656 (GC reserved = 560)
(32GB, 32MB zone, 8 conv, 1016 seq)
legacy + zoned multi				656 (GC reserved = 560)		656 (GC reserved = 560)
(32GB, 256MB legacy block + 32MB zone, 1016 seq)

Thanks.
> > +		usable_segs -= (get_sb(segment0_blkaddr) >> get_sb(log_blocks_per_seg));
> > +
> >  	return usable_segs;
> >  #endif
> >  	return get_sb(segment_count_main);
> > -- 
> > 2.43.0

Re: [PATCH] libf2fs: Fix calculation of usable segments for single zoned

[Markus Elfring]

…
> This patch fixes the bug by …

* How do you think about to choose another imperative wording
  for an improved change description?
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.12-rc2#n94

* Would you like to add any tags (like “Fixes” and “Cc”) accordingly?


Regards,
Markus