lkml.org 
[lkml]   [2017]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [RFC 2/5] fs: freeze on suspend and thaw on resume
Date
On Tue, 2017-10-03 at 22:23 +0200, Luis R. Rodriguez wrote:
> On Tue, Oct 03, 2017 at 08:02:22PM +0000, Bart Van Assche wrote:
> > On Tue, 2017-10-03 at 11:53 -0700, Luis R. Rodriguez wrote:
> > > +static bool super_allows_freeze(struct super_block *sb)
> > > +{
> > > + return !!(sb->s_type->fs_flags & FS_FREEZE_ON_SUSPEND);
> > > +}
> >
> > A minor comment: if "!!" would be left out the compiler will perform the
> > conversion from int to bool implicitly
>
> For all compilers?

Let's have a look at the output of the following commands:

$ PAGER= git grep 'typedef.*[[:blank:]]bool;' include
include/linux/types.h:typedef _Bool bool;
$ PAGER= git grep std= Makefile
Makefile: -fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS)
Makefile: -std=gnu89 $(call cc-option,-fno-PIE)

From https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/C-Dialect-Options.html#C-Dialect-Options:
‘gnu89’
GNU dialect of ISO C90 (including some C99 features).

I think this means that the Linux kernel tree can only be compiled correctly
by compilers that support the C11 type _Bool.

> > Anyway, I agree with the approach of this patch and I think
> > that freezing filesystems before processes are frozen would be a big step
> > forward.
>
> Great! But please note, the current implementation calls fs_suspend_freeze()
> *after* try_to_freeze_tasks(), ie: this implementation freezes userspace and
> only after then filesystems.

What will the impact be of that choice on filesystems implemented in userspace?

Thanks,

Bart.
\
 
 \ /
  Last update: 2017-10-03 22:34    [W:0.103 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site