Re: Problem in EROFS: Not able to read the files after mount

[Saumya Panda <saumya.iisc@gmail.com>]

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Hi Gao,
  Thanks for the info. After I enabled the said configuration, I am now
able to read the files after mount. But I am seeing Squashfs has better
compression ratio compared to Erofs (more than 60% than that of Erofs). Am
I missing something? I used lz4hc while making the Erofs image.

ls -l enwik*
-rw-r--r-- 1 saumya users  61280256 Jan 21 03:22 enwik8.erofs.img
-rw-r--r-- 1 saumya users  37355520 Jan 21 03:34 enwik8.sqsh
-rw-r--r-- 1 saumya users 558133248 Jan 21 03:25 enwik9.erofs.img
-rw-r--r-- 1 saumya users 331481088 Jan 21 03:35 enwik9.sqsh

On Mon, Jan 20, 2020 at 1:11 PM Gao Xiang <hsiangkao@aol.com> wrote:

> Hi Saumya,
>
> On Mon, Jan 20, 2020 at 12:25:15PM +0530, Saumya Panda wrote:
> > Hi Experts,
> >    I am testing EROFS in openSuse(Kernel: 5.4.7-1-default). I used the
> > enwik8 and enwik9 as source file (
> > https://cs.fit.edu/~mmahoney/compression/textdata.html) for compression.
> > But after I mount the erofs image, I am not able to read it (it is saying
> > operation not permitted). Simple "ls" command is not working. But if I
> > create EROFS image without compression flag, then after mount I am able
> to
> > read the files. Seems there is some problem during compression.
> >
> > I will appreciate if someone can help me out why this is happening.
>
> Could you please check if your opensuse kernel has been enabled
> the following configuration?
>
> CONFIG_EROFS_FS_ZIP=y
> CONFIG_EROFS_FS_CLUSTER_PAGE_LIMIT=1
>
> By default, they should be enabled, but it seems not according to
> the following information you mentioned.
>
> Thanks,
> Gao Xiang
>
> >
> > Steps followed:
> > *Erofs image creation & mount: *
> > mkfs.erofs -zlz4hc enwik8.erofs.img enwik8/
> > mkfs.erofs 1.0
> >         c_version:           [     1.0]
> >         c_dbg_lvl:           [       0]
> >         c_dry_run:           [       0]
> > mount enwik8.erofs.img /mnt/enwik8/ -t erofs -o loop
> >
> > ls -l /mnt/enwik8/
> > ls: cannot access '/mnt/enwik8/enwik8': Operation not supported
> > total 0
> > -????????? ? ? ? ?            ? enwik8
> >
> > The problem seen for both lz4 & lz4hc.
> >
> > *Erofs image creation & mount without compression: *
> > mkfs.erofs  enwik8_nocomp.erofs.img enwik8/
> > mkfs.erofs 1.0
> >         c_version:           [     1.0]
> >         c_dbg_lvl:           [       0]
> >         c_dry_run:           [       0]
> >
> > mount enwik8_nocomp.erofs.img /mnt/enwik8_nocomp/ -t erofs -o loop
> >
> > ls -l /mnt/enwik8_nocomp/
> > total 97660
> > -rw-r--r-- 1 root root 100000000 Jan 20 01:27 enwik8
> >
> > *Original enwik8 file:*
> > ls -l enwik8
> > total 97660
> > -rw-r--r-- 1 root root 100000000 Jan 20 01:14 enwik8
> >
> > *Source code used for Lz4 and Erofs utils:*
> > https://github.com/hsiangkao/erofs-utils
> > https://github.com/lz4/lz4
> >
> > --
> > Thanks,
> > Saumya Prakash Panda
>


-- 
Thanks,
Saumya Prakash Panda

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