Re: ping //Re: [PATCH v2 0/2] squashfs: Add the mount parameter "threads="

[Xiaoming Ni]

On 2022/8/31 2:34, Phillip Lougher wrote:
> On 30/08/2022 19:08, Phillip Lougher wrote:
> > On 30/08/2022 14:38, Xiaoming Ni wrote:
> > > On 2022/8/29 7:18, Phillip Lougher wrote:
>
> > > > As regards points 1 - 3, personally I would add a default kernel
> > > > configuration option that keeps the existing behaviour, build time
> > > > selectable only, no additional mount time options.  Then a
> > > > kernel configuration option that allows the different decompressors
> > > > to be selected at mount time, but which always builds all the
> > > > decompressors.  This will avoid the silliness of point 2, and
> > > Would it be better to allow flexible selection of decompression mode 
> > > combinations?
> >
> > I told you I don't like that (*).  I also told you I want the default 
> > behaviour to be the current behaviour.
> >
> > Feel free to disagree, but that isn't a good way to get your patch
> > reviewed or accepted by me.
> >
> > Cheers
> >
> > Phillip
> >
> > (*) Adding options to select the decompressor at mount time, but,
> >      also allowing only 1 - 2 decompressors to be built is a waste of
> >      time.  It has the effect of giving something with one hand and
> >      taking it alway with the other.  Build the lot, this also
> >      keeps it simple.
>
> It also splatters super.c with #ifdef CONFIG lines.
>
> phillip@phoenix:/external/stripe/linux/fs/squashfs$ grep "CONFIG_" super.c
> #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU
> #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU
> #ifdef CONFIG_SQUASHFS_DECOMP_DEFAULT_SINGLE
> #elif defined(CONFIG_SQUASHFS_DECOMP_DEFAULT_MULTI)
> #elif defined(CONFIG_SQUASHFS_DECOMP_DEFAULT_PERCPU)
>
> Or
>
> static int squashfs_parse_param_threads(const char *str, struct 
> squashfs_mount_opts *opts)
> {
>          unsigned long num;
>          int ret;
> #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
>          if (strcmp(str, "single") == 0) {
>                  opts->thread_ops = &squashfs_decompressor_single;
>                  return 0;
>          }
> #endif
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI
>          if (strcmp(str, "multi") == 0) {
>                  opts->thread_ops = &squashfs_decompressor_multi;
>                  return 0;
>          }
> #endif
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU
>          if (strcmp(str, "percpu") == 0) {
>                  opts->thread_ops = &squashfs_decompressor_percpu;
>                  return 0;
>          }
> #endif
>          ret = kstrtoul(str, 0, &num);
>          if (ret != 0 || num == 0)
>                  return -EINVAL;
> #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
>          if (num == 1) {
>                  opts->thread_ops = &squashfs_decompressor_single;
>                  return 0;
>          }
> #endif
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI
>          opts->thread_ops = &squashfs_decompressor_multi;
>          if (num > opts->thread_ops->max_decompressors())
>                  num = opts->thread_ops->max_decompressors();
>          opts->thread_num = (int)num;
>          return 0;
> #else
>          return -EINVAL;
> #endif
> }
>
> SNIP
>
> static int squashfs_show_options(struct seq_file *s, struct dentry *root)
> {
>          struct super_block *sb = root->d_sb;
>          struct squashfs_sb_info *msblk = sb->s_fs_info;
>
>          if (msblk->panic_on_errors)
>                  seq_puts(s, ",errors=panic");
>          else
>                  seq_puts(s, ",errors=continue");
>
> #ifdef CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU
>          /*
>           * thread=percpu and thread=<number> have different 
> configuration effects.
>           * the parameters need to be treated differently when they are 
> displayed.
>           */
>          if (msblk->thread_ops == &squashfs_decompressor_percpu) {
>                  seq_puts(s, ",threads=percpu");
>                  return 0;
>          }
> #endif
>          seq_printf(s, ",threads=%u", msblk->max_thread_num);
>          return 0;
> }
>
> static int squashfs_init_fs_context(struct fs_context *fc)
> {
>          struct squashfs_mount_opts *opts;
>
>          opts = kzalloc(sizeof(*opts), GFP_KERNEL);
>          if (!opts)
>                  return -ENOMEM;
>
> #ifdef CONFIG_SQUASHFS_DECOMP_DEFAULT_SINGLE
>          opts->thread_ops = &squashfs_decompressor_single;
> #elif defined(CONFIG_SQUASHFS_DECOMP_DEFAULT_MULTI)
>          opts->thread_ops = &squashfs_decompressor_multi,
> #elif defined(CONFIG_SQUASHFS_DECOMP_DEFAULT_PERCPU)
>          opts->thread_ops = &squashfs_decompressor_percpu;
> #endif
Thanks for your guidance, I will update it in v3 patch as soon as possible

Thanks

Xiaoming Ni