* [PATCH v5] zram: break the strict dependency from lzo
@ 2020-11-15 10:15 Rui Salvaterra
2020-11-19 22:26 ` Minchan Kim
0 siblings, 1 reply; 6+ messages in thread
From: Rui Salvaterra @ 2020-11-15 10:15 UTC (permalink / raw)
To: minchan, ngupta, sergey.senozhatsky.work
Cc: linux-block, linux-kernel, Rui Salvaterra
From the beginning, the zram block device always enabled CRYPTO_LZO, since
lzo-rle is hardcoded as the fallback compression algorithm. As a consequence, on
systems where another compression algorithm is chosen (e.g. CRYPTO_ZSTD), the
lzo kernel module becomes unused, while still having to be built/loaded.
This patch removes the hardcoded lzo-rle dependency and allows the user to
select the default compression algorithm for zram at build time. The previous
behaviour is kept, as the default algorithm is still lzo-rle.
Suggested-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
---
v5: incorporate Minchan's feedback. Allow the user to choose a default algorithm.
v4: incorporate Sergey's feedback and fix a small typo.
v3: fix the default selection when lzo isn't present. Rebase against 5.10-rc1.
v2: fix the dependency on CRYPTO.
I believe this is the final version, but it does deserve some comment. Given the
choice of having more preprocessor #if/#endif directives in C files or making
the kconfig a bit more complex, I went for the latter. However, since kconfig
choices can only be boolean, I had to devise a way to make a string selection
based on the boolean choice, hence the ZRAM_DEF_COMP symbol.
I also tried to make the ZRAM_AUTOSEL_ALGO definition a bit less painful to the
eye, while still allowing for the compression algorithms to be selected as
modules, as per Sergey's suggestion.
drivers/block/zram/Kconfig | 49 ++++++++++++++++++++++++++++++++++-
drivers/block/zram/zcomp.c | 2 ++
drivers/block/zram/zram_drv.c | 2 +-
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..cde089c30ffb 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -2,7 +2,6 @@
config ZRAM
tristate "Compressed RAM block device support"
depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
- select CRYPTO_LZO
help
Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
Pages written to these disks are compressed and stored in memory
@@ -14,6 +13,54 @@ config ZRAM
See Documentation/admin-guide/blockdev/zram.rst for more information.
+choice
+ prompt "Default zram compression algorithm"
+ depends on ZRAM
+
+config ZRAM_DEF_COMP_LZORLE
+ bool "lzo-rle"
+ depends on CRYPTO_LZO
+
+config ZRAM_DEF_COMP_ZSTD
+ bool "zstd"
+ depends on CRYPTO_ZSTD
+
+config ZRAM_DEF_COMP_LZ4
+ bool "lz4"
+ depends on CRYPTO_LZ4
+
+config ZRAM_DEF_COMP_LZO
+ bool "lzo"
+ depends on CRYPTO_LZO
+
+config ZRAM_DEF_COMP_LZ4HC
+ bool "lz4hc"
+ depends on CRYPTO_LZ4HC
+
+config ZRAM_DEF_COMP_842
+ bool "842"
+ depends on CRYPTO_842
+
+endchoice
+
+config ZRAM_DEF_COMP
+ string
+ default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
+ default "zstd" if ZRAM_DEF_COMP_ZSTD
+ default "lz4" if ZRAM_DEF_COMP_LZ4
+ default "lzo" if ZRAM_DEF_COMP_LZO
+ default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
+ default "842" if ZRAM_DEF_COMP_842
+
+config ZRAM_AUTOSEL_ALGO
+ def_bool y
+ depends on ZRAM && \
+ !(CRYPTO_LZ4=m || CRYPTO_LZ4=y || \
+ CRYPTO_LZ4HC=m || CRYPTO_LZ4HC=y || \
+ CRYPTO_842=m || CRYPTO_842=y || \
+ CRYPTO_ZSTD=m || CRYPTO_ZSTD=y)
+ select CRYPTO_LZO
+
config ZRAM_WRITEBACK
bool "Write back incompressible or idle page to backing device"
depends on ZRAM
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 33e3b76c4fa9..052aa3f65514 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -15,8 +15,10 @@
#include "zcomp.h"
static const char * const backends[] = {
+#if IS_ENABLED(CONFIG_CRYPTO_LZO)
"lzo",
"lzo-rle",
+#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
"lz4",
#endif
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 1b697208d661..9ddccb968c68 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,7 +42,7 @@ static DEFINE_IDR(zram_index_idr);
static DEFINE_MUTEX(zram_index_mutex);
static int zram_major;
-static const char *default_compressor = "lzo-rle";
+static const char *default_compressor = CONFIG_ZRAM_DEF_COMP;
/* Module params (documentation at end) */
static unsigned int num_devices = 1;
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v5] zram: break the strict dependency from lzo
2020-11-15 10:15 [PATCH v5] zram: break the strict dependency from lzo Rui Salvaterra
@ 2020-11-19 22:26 ` Minchan Kim
2020-11-20 9:10 ` Rui Salvaterra
0 siblings, 1 reply; 6+ messages in thread
From: Minchan Kim @ 2020-11-19 22:26 UTC (permalink / raw)
To: Rui Salvaterra; +Cc: ngupta, sergey.senozhatsky.work, linux-block, linux-kernel
On Sun, Nov 15, 2020 at 10:15:14AM +0000, Rui Salvaterra wrote:
> From the beginning, the zram block device always enabled CRYPTO_LZO, since
> lzo-rle is hardcoded as the fallback compression algorithm. As a consequence, on
> systems where another compression algorithm is chosen (e.g. CRYPTO_ZSTD), the
> lzo kernel module becomes unused, while still having to be built/loaded.
>
> This patch removes the hardcoded lzo-rle dependency and allows the user to
> select the default compression algorithm for zram at build time. The previous
> behaviour is kept, as the default algorithm is still lzo-rle.
>
> Suggested-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> Suggested-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
> ---
> v5: incorporate Minchan's feedback. Allow the user to choose a default algorithm.
> v4: incorporate Sergey's feedback and fix a small typo.
> v3: fix the default selection when lzo isn't present. Rebase against 5.10-rc1.
> v2: fix the dependency on CRYPTO.
>
> I believe this is the final version, but it does deserve some comment. Given the
> choice of having more preprocessor #if/#endif directives in C files or making
> the kconfig a bit more complex, I went for the latter. However, since kconfig
> choices can only be boolean, I had to devise a way to make a string selection
> based on the boolean choice, hence the ZRAM_DEF_COMP symbol.
> I also tried to make the ZRAM_AUTOSEL_ALGO definition a bit less painful to the
> eye, while still allowing for the compression algorithms to be selected as
> modules, as per Sergey's suggestion.
>
> drivers/block/zram/Kconfig | 49 ++++++++++++++++++++++++++++++++++-
> drivers/block/zram/zcomp.c | 2 ++
> drivers/block/zram/zram_drv.c | 2 +-
> 3 files changed, 51 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
> index fe7a4b7d30cf..cde089c30ffb 100644
> --- a/drivers/block/zram/Kconfig
> +++ b/drivers/block/zram/Kconfig
> @@ -2,7 +2,6 @@
> config ZRAM
> tristate "Compressed RAM block device support"
> depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
> - select CRYPTO_LZO
> help
> Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
> Pages written to these disks are compressed and stored in memory
> @@ -14,6 +13,54 @@ config ZRAM
>
> See Documentation/admin-guide/blockdev/zram.rst for more information.
>
> +choice
> + prompt "Default zram compression algorithm"
> + depends on ZRAM
> +
> +config ZRAM_DEF_COMP_LZORLE
> + bool "lzo-rle"
> + depends on CRYPTO_LZO
> +
> +config ZRAM_DEF_COMP_ZSTD
> + bool "zstd"
> + depends on CRYPTO_ZSTD
> +
> +config ZRAM_DEF_COMP_LZ4
> + bool "lz4"
> + depends on CRYPTO_LZ4
> +
> +config ZRAM_DEF_COMP_LZO
> + bool "lzo"
> + depends on CRYPTO_LZO
> +
> +config ZRAM_DEF_COMP_LZ4HC
> + bool "lz4hc"
> + depends on CRYPTO_LZ4HC
> +
> +config ZRAM_DEF_COMP_842
> + bool "842"
> + depends on CRYPTO_842
> +
> +endchoice
> +
> +config ZRAM_DEF_COMP
> + string
> + default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
> + default "zstd" if ZRAM_DEF_COMP_ZSTD
> + default "lz4" if ZRAM_DEF_COMP_LZ4
> + default "lzo" if ZRAM_DEF_COMP_LZO
> + default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
> + default "842" if ZRAM_DEF_COMP_842
> +
> +config ZRAM_AUTOSEL_ALGO
> + def_bool y
> + depends on ZRAM && \
> + !(CRYPTO_LZ4=m || CRYPTO_LZ4=y || \
> + CRYPTO_LZ4HC=m || CRYPTO_LZ4HC=y || \
> + CRYPTO_842=m || CRYPTO_842=y || \
> + CRYPTO_ZSTD=m || CRYPTO_ZSTD=y)
> + select CRYPTO_LZO
> +
Hi Rui,
What's the purpose of ZRAM_AUTOSEL_ALGO?
If you and Sergey already discussed, sorry about the missing it.
Below doesn't work for your goal?
diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..7f3c50f5f87e 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -2,7 +2,6 @@
config ZRAM
tristate "Compressed RAM block device support"
depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
- select CRYPTO_LZO
help
Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
Pages written to these disks are compressed and stored in memory
@@ -14,6 +13,32 @@ config ZRAM
See Documentation/admin-guide/blockdev/zram.rst for more information.
+
+choice
+ prompt "zram default compressor"
+ default ZRAM_COMP_LZO_DEF
+ depends on ZRAM || CRYPTO_LZ4
+ help
+ a
+
+config ZRAM_COMP_LZO_DEF
+ bool "lzo"
+ select CRYPTO_LZO
+ help
+ b
+
+config ZRAM_COMP_LZ4_DEF
+ bool "lz4"
+ depends on CRYPTO_LZ4
+ help
+ c
+endchoice
+
+config ZRAM_DEF_COMP
+ string
+ default "lzo" if ZRAM_COMP_LZO_DEF
+ default "lz4" if ZRAM_COMP_LZ4_DEF
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v5] zram: break the strict dependency from lzo
2020-11-19 22:26 ` Minchan Kim
@ 2020-11-20 9:10 ` Rui Salvaterra
2020-11-20 21:40 ` Minchan Kim
0 siblings, 1 reply; 6+ messages in thread
From: Rui Salvaterra @ 2020-11-20 9:10 UTC (permalink / raw)
To: Minchan Kim; +Cc: ngupta, sergey.senozhatsky.work, linux-block, linux-kernel
Hi, Minchan,
On Thu, 19 Nov 2020 at 22:26, Minchan Kim <minchan@kernel.org> wrote:
>
> What's the purpose of ZRAM_AUTOSEL_ALGO?
> If you and Sergey already discussed, sorry about the missing it.
The purpose of ZRAM_AUTOSEL_ALGO is to make sure at least one of the
required compression algorithms is enabled, either as a module or
built-in. I believe Sergey agreed with the reasoning behind it, but
he'll let us know if I misunderstood. :)
> Below doesn't work for your goal?
Unfortunately, it doesn't. :( It breaks the dependency chain, allowing
you to deselect all compression algorithms in the crypto menu, and
consequently disabling zram. This is only my opinion (and I know
select directives should be very well justified), but I believe that
it should be zram to make sure its required libraries are enabled, and
not the other way around. Having to select a compression algorithm in
the crypto menu for the zram block device to appear in the block
devices menu seems backwards to me.
Thanks,
Rui
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5] zram: break the strict dependency from lzo
2020-11-20 9:10 ` Rui Salvaterra
@ 2020-11-20 21:40 ` Minchan Kim
2020-11-21 0:44 ` Rui Salvaterra
0 siblings, 1 reply; 6+ messages in thread
From: Minchan Kim @ 2020-11-20 21:40 UTC (permalink / raw)
To: Rui Salvaterra; +Cc: ngupta, sergey.senozhatsky.work, linux-block, linux-kernel
On Fri, Nov 20, 2020 at 09:10:13AM +0000, Rui Salvaterra wrote:
> Hi, Minchan,
>
> On Thu, 19 Nov 2020 at 22:26, Minchan Kim <minchan@kernel.org> wrote:
> >
> > What's the purpose of ZRAM_AUTOSEL_ALGO?
> > If you and Sergey already discussed, sorry about the missing it.
>
> The purpose of ZRAM_AUTOSEL_ALGO is to make sure at least one of the
> required compression algorithms is enabled, either as a module or
> built-in. I believe Sergey agreed with the reasoning behind it, but
> he'll let us know if I misunderstood. :)
>
> > Below doesn't work for your goal?
>
> Unfortunately, it doesn't. :( It breaks the dependency chain, allowing
> you to deselect all compression algorithms in the crypto menu, and
Hi Rui,
I don't understand it. Please see below. ZRAM_COMP_LZO_DEF select
CRYPTO_LZO, not relying on it. If system supports other CRYPTO module
it will show on choice list. Otherwise, default lzo will be always
there and select CRYPTO_LZO.
Do I miss your point?
+
+choice
+ prompt "zram default compressor"
+ default ZRAM_COMP_LZO_DEF
+ depends on ZRAM || CRYPTO_LZ4
+ help
+ a
+
+config ZRAM_COMP_LZO_DEF
+ bool "lzo"
+ select CRYPTO_LZO
+ help
+ b
+
+config ZRAM_COMP_LZ4_DEF
+ bool "lz4"
+ depends on CRYPTO_LZ4
+ help
+ c
+endchoice
+
+config ZRAM_DEF_COMP
+ string
+ default "lzo" if ZRAM_COMP_LZO_DEF
+ default "lz4" if ZRAM_COMP_LZ4_DEF
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5] zram: break the strict dependency from lzo
2020-11-20 21:40 ` Minchan Kim
@ 2020-11-21 0:44 ` Rui Salvaterra
2020-11-22 9:40 ` Rui Salvaterra
0 siblings, 1 reply; 6+ messages in thread
From: Rui Salvaterra @ 2020-11-21 0:44 UTC (permalink / raw)
To: Minchan Kim; +Cc: ngupta, sergey.senozhatsky.work, linux-block, linux-kernel
Hi, Minchan,
On Fri, 20 Nov 2020 at 21:40, Minchan Kim <minchan@kernel.org> wrote:
>
> Do I miss your point?
Well, it's quite possible I mis{read,applied} your patch. It's late
here, I'll test it with fresher brains tomorrow to see if it's
functionally equivalent.
Thanks,
Rui
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v5] zram: break the strict dependency from lzo
2020-11-21 0:44 ` Rui Salvaterra
@ 2020-11-22 9:40 ` Rui Salvaterra
0 siblings, 0 replies; 6+ messages in thread
From: Rui Salvaterra @ 2020-11-22 9:40 UTC (permalink / raw)
To: Minchan Kim; +Cc: ngupta, sergey.senozhatsky.work, linux-block, linux-kernel
Hi, Minchan,
On Sat, 21 Nov 2020 at 00:44, Rui Salvaterra <rsalvaterra@gmail.com> wrote:
>
> Well, it's quite possible I mis{read,applied} your patch.
And I obviously did. Your kconfig suggestion does basically the same,
in a more simplified way. I guess a v6 is in order.
Thanks,
Rui
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-11-22 9:40 UTC | newest]
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2020-11-15 10:15 [PATCH v5] zram: break the strict dependency from lzo Rui Salvaterra
2020-11-19 22:26 ` Minchan Kim
2020-11-20 9:10 ` Rui Salvaterra
2020-11-20 21:40 ` Minchan Kim
2020-11-21 0:44 ` Rui Salvaterra
2020-11-22 9:40 ` Rui Salvaterra
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