On Thu, Oct 13, 2016 at 03:25:57PM +0800, Qu Wenruo wrote:
> At 10/13/2016 01:26 AM, David Sterba wrote:
> > On Wed, Oct 12, 2016 at 10:01:27PM +0800, Qu Wenruo wrote:
> >> On 10/12/2016 09:58 PM, Abhay Sachan wrote:
> >>> Hi,
> >>> I tried building latest btrfs progs on CentOS 6, "./configure" failed
> >>> with the error:
> >>> checking for FIEMAP_EXTENT_SHARED defined in linux/fiemap.h... no
> >>> configure: error: no definition of FIEMAP_EXTENT_SHARED found
> >>> Any ideas what am I lacking in the system?
> >> Your kernel is too old and its header doesn't support
> >> FIEMAP_EXTENT_SHARED flag for fiemap ioctl.
> > As this is not the first time, I wonder if we could provide a defintion
> > of the macro in progs, regardless of the installed headers. Note that
> > this does not mean the running kernel is old. Previously the user said
> > he was running a 4.4 kernel  (or it could be any other kernel
> > version). For that combination of headers and running kernel, I think
> > it's ok to add a fallback definition.
> Yes, fallback definition is good for case like running kernel supports
> SHARED_EXTENT flag, but not kernel header.
> But I'm a little concerned about such fallback definition will lead to
> corrupted result for "fi du".
Well, not corrupted bug wrong. The shared data will be reported as
> >> And since that flag is very important for tools like "btrfs filesystem
> >> du", for old kernel doesn't support EXTENT_SHARED flag, we have no
> >> choice but abort configuration.
> > The check was added to configure so it's caught earlier than during
> > build. The 'fi du' command is useful, but not IMO critical to stop the
> > build.
> What about just disabling subcommands using SHARED_EXTENT flag?
> Like "fi du".
This would need to be checked at runtime, based only on kernel version.
I think we can do that, print a warning in 'fi du' but otherwise let it
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