Patchwork lz4hc compression in UBIFS?

login
register
mail settings
Submitter Konstantin Tokarev
Date Oct. 24, 2013, 3:15 p.m.
Message ID <106621382627723@web13g.yandex.ru>
Download mbox | patch
Permalink /patch/285935/
State New
Headers show

Comments

Konstantin Tokarev - Oct. 24, 2013, 3:15 p.m.
24.10.2013, 18:20, "Konstantin Tokarev" <annulen@yandex.ru>:
> 23.10.2013, 22:26, "Yann Collet" <yann.collet.73@gmail.com>:
>
>>  UBIFS error (pid 4288): ubifs_decompress: cannot decompress 12 bytes,
>>  (...)
>>          data size      12
>>          data:
>>          00000000: 1f 00 01 00 ff e8 50 00 00 00 00 00
>>
>>  The compressed format is correct.
>>  It describes a flow of 00, of size ~500.
>>
>>  So the problem seems more likely on the decompression side.
>>
>>  Are you sure you are providing "12" as the "input size" parameter ? and that
>>  the "maximum output size" parameter is correctly provided ? (i.e. >= to
>>  original data size)
>
> Decompression code in kernel[1] is heavily modified. In particular, lz4_uncompress
> function (used in this case) does not have input size parameter at all,
> while it's present in lz4_uncompress_unknownoutputsize.
>
> [1] lib/lz4/lz4_decompress.c

Attached patch to crypto API wrapper for lz4hc seems to fix the issue. I can save
and read files on LZ4HC-compressed volume, and I'm running on LZ4HC-compressed rootfs,
flashed from mkfs.ubifs generated image (patch by Elie De Brauwer). My software
works correctly.

Unfortunately, on my board LZ4HC-compressed UBIFS volume performs noticeable worse
than LZO, while still faster than zlib. I guess the reason is that CPU is no longer a
bottleneck for my system, but NAND speed.

Thank you all for your help!
Konstantin Tokarev - Oct. 28, 2013, 4:22 p.m.
24.10.2013, 19:15, "Konstantin Tokarev" <annulen@yandex.ru>:
> Attached patch to crypto API wrapper for lz4hc seems to fix the issue. I can save
> and read files on LZ4HC-compressed volume, and I'm running on LZ4HC-compressed rootfs,
> flashed from mkfs.ubifs generated image (patch by Elie De Brauwer). My software
> works correctly.
>
> Unfortunately, on my board LZ4HC-compressed UBIFS volume performs noticeable worse
> than LZO, while still faster than zlib. I guess the reason is that CPU is no longer a
> bottleneck for my system, but NAND speed.
>
> Thank you all for your help!

Can anyone review the correctness of my patch? Looks like API of LZ4 decompressor is
used wrong way in crypto API.
Florian Fainelli - Oct. 28, 2013, 4:45 p.m.
2013/10/28 Konstantin Tokarev <annulen@yandex.ru>:
>
>
> 24.10.2013, 19:15, "Konstantin Tokarev" <annulen@yandex.ru>:
>> Attached patch to crypto API wrapper for lz4hc seems to fix the issue. I can save
>> and read files on LZ4HC-compressed volume, and I'm running on LZ4HC-compressed rootfs,
>> flashed from mkfs.ubifs generated image (patch by Elie De Brauwer). My software
>> works correctly.
>>
>> Unfortunately, on my board LZ4HC-compressed UBIFS volume performs noticeable worse
>> than LZO, while still faster than zlib. I guess the reason is that CPU is no longer a
>> bottleneck for my system, but NAND speed.
>>
>> Thank you all for your help!
>
> Can anyone review the correctness of my patch? Looks like API of LZ4 decompressor is
> used wrong way in crypto API.

Can you make a formal submission of it? That would probably help reviewing it.
--
Florian

Patch

diff --git a/crypto/lz4.c b/crypto/lz4.c
index 4586dd1..91a0613 100644
--- a/crypto/lz4.c
+++ b/crypto/lz4.c
@@ -66,9 +66,8 @@  static int lz4_decompress_crypto(struct crypto_tfm *tfm, const u8 *src,
 {
 	int err;
 	size_t tmp_len = *dlen;
-	size_t __slen = slen;
 
-	err = lz4_decompress(src, &__slen, dst, tmp_len);
+	err = lz4_decompress_unknownoutputsize(src, slen, dst, &tmp_len);
 	if (err < 0)
 		return -EINVAL;
 
diff --git a/crypto/lz4hc.c b/crypto/lz4hc.c
index 151ba31..9987741 100644
--- a/crypto/lz4hc.c
+++ b/crypto/lz4hc.c
@@ -66,9 +66,8 @@  static int lz4hc_decompress_crypto(struct crypto_tfm *tfm, const u8 *src,
 {
 	int err;
 	size_t tmp_len = *dlen;
-	size_t __slen = slen;
 
-	err = lz4_decompress(src, &__slen, dst, tmp_len);
+	err = lz4_decompress_unknownoutputsize(src, slen, dst, &tmp_len);
 	if (err < 0)
 		return -EINVAL;