Libguestfs - Jul 2018 - Re: [PATCH 1/2] file: Add missing include for FALLOC_FL_*

On RHEL 7.5 we need to include <linux/falloc.h> for FALLOC_FL_* macros.
Without the macros, fallocate is never used and we fall back to manual
zeroing.

Here are examples runs with this change with a local file on ext4:

$ export SOCK=/tmp/nbd.sock
$ export FILE=/var/tmp/nbd.img
$ export BLOCK=/dev/loop2

$ src/nbdkit -f plugins/file/.libs/nbdkit-file-plugin.so file=$FILE -U $SOCK
$ time qemu-img convert -n -f raw -O raw /var/tmp/fedora-27.img nbd:unix:$SOCK

real    0m13.361s
user    0m0.127s
sys     0m0.668s

$ src/nbdkit -f plugins/file/.libs/nbdkit-file-plugin.so file=$BLOCK -U $SOCK
$ time qemu-img convert -n -f raw -O raw /var/tmp/fedora-27.img nbd:unix:$SOCK

real    0m13.491s
user    0m0.129s
sys     0m0.612s
---
 plugins/file/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/plugins/file/file.c b/plugins/file/file.c
index 4210adb..fb20622 100644
--- a/plugins/file/file.c
+++ b/plugins/file/file.c
@@ -41,6 +41,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
+#include <linux/falloc.h>   /* For FALLOC_FL_* on RHEL, glibc < 2.18
*/
 
 #include <nbdkit-plugin.h>
 
-- 
2.17.1

On 07/29/2018 06:35 AM, Nir Soffer wrote:
> On RHEL 7.5 we need to include <linux/falloc.h> for FALLOC_FL_*
macros.
> Without the macros, fallocate is never used and we fall back to manual
> zeroing.
> 
> @@ -41,6 +41,7 @@
>   #include <sys/types.h>
>   #include <sys/stat.h>
>   #include <errno.h>
> +#include <linux/falloc.h>   /* For FALLOC_FL_* on RHEL, glibc <
2.18 */
This header is not available on all platforms; does it need a configure 
check, or do we not care about non-Linux compilation?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

On Mon, Jul 30, 2018 at 6:38 PM Eric Blake <eblake@redhat.com> wrote:
> On 07/29/2018 06:35 AM, Nir Soffer wrote:
> > On RHEL 7.5 we need to include <linux/falloc.h> for FALLOC_FL_*
macros.
> > Without the macros, fallocate is never used and we fall back to manual
> > zeroing.
> >
>
> > @@ -41,6 +41,7 @@
> >   #include <sys/types.h>
> >   #include <sys/stat.h>
> >   #include <errno.h>
> > +#include <linux/falloc.h>   /* For FALLOC_FL_* on RHEL, glibc
< 2.18 */
>
> This header is not available on all platforms; does it need a configure
> check, or do we not care about non-Linux compilation?

I'm not sure if nbdkit tries to be portable, but I think we should care.

Is #if defined(__linux__) good enough for this?

Nir

On Mon, Jul 30, 2018 at 09:52:46AM -0500, Eric Blake
wrote:
> On 07/29/2018 06:35 AM, Nir Soffer wrote:
> >On RHEL 7.5 we need to include <linux/falloc.h> for FALLOC_FL_*
macros.
> >Without the macros, fallocate is never used and we fall back to manual
> >zeroing.
> >
> 
> >@@ -41,6 +41,7 @@
> >  #include <sys/types.h>
> >  #include <sys/stat.h>
> >  #include <errno.h>
> >+#include <linux/falloc.h>   /* For FALLOC_FL_* on RHEL, glibc
< 2.18 */
> 
> This header is not available on all platforms; does it need a
> configure check, or do we not care about non-Linux compilation?
We should care about at least the *BSDs.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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