Re: RE: [PATCH] lib : lz4 using put_unaligned_le16 instead of put_unaligned

Re: RE: [PATCH] lib : lz4 using put_unaligned_le16 instead of put_unaligned

[Eunbong Song]

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Hello. 

>Can you check if this patch fix your problem also?
Unfortunately your patch does not fix my problem. My test logs are as follow.
I did the same test with lzo compression algorithm and with my patch, and 
these work well.

debug_shell:/user> echo 1 > /sys/block/zram0/reset
debug_shell:/user> echo lz4 > /sys/block/zram0/comp_algorithm
debug_shell:/user> echo 520M > /sys/block/zram0/disksize
debug_shell:/user> mkfs.ext4 /dev/zram0
mke2fs 1.41.4 (27-Jan-2009)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
33280 inodes, 133120 blocks
6656 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=138412032
5 block groups
32768 blocks per group, 32768 fragments per group
6656 inodes per group
Superblock backups stored on blocks:
        32768, 98304

Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 25 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
debug_shell:/user> mount /dev/zram0 /mnt/
EXT4-fs (zram0): unsupported inode size: 272
mount: wrong fs type, bad option, bad superblock on /dev/zram0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so



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Re: RE: [PATCH] lib : lz4 using put_unaligned_le16 instead of put_unaligned

[Eunbong Song]

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>  If your patch is applied, the data which is compressed
> by your big-endian system won't be decompressed in other little-endian system.

I can't understand this. Please, could you explain this more ?
My patch just replaces put_unaligned with put_unaligned_le16. and this just write compression data
in little endian byte-order  regardless of machine byte-order, like ext file system. 
So, i guess there is no  problem what you pointed 

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Re: Re: [PATCH] lib : lz4 using put_unaligned_le16 instead of put_unaligned

[Greg KH]

On Tue, Jul 22, 2014 at 02:17:52AM +0000, Eunbong Song wrote:
> 
> > Odd line wrapping :(
> 
> Sorry, for this. 
> 
> > Anyway, is this a new problem?  Or something that has always been there
> > in this compression function?
> 
> Actually, i have tested zram with lz4 functions in my board(mips64 big endian). 
> Everytime  i try to mount my ext4 zram image i have failed. 
> After applying this patch, that problem was disappeared.

So it's never worked?

Did you test on a little endian machine after making this change?

Re: Re: [PATCH] lib : lz4 using put_unaligned_le16 instead of put_unaligned

[Eunbong Song]

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> Odd line wrapping :(

Sorry, for this. 

> Anyway, is this a new problem?  Or something that has always been there
> in this compression function?

Actually, i have tested zram with lz4 functions in my board(mips64 big endian). 
Everytime  i try to mount my ext4 zram image i have failed. 
After applying this patch, that problem was disappeared.

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