Libguestfs - Jun 2021 - [libnbd PATCH 01/20] fuse: Only support defined fallocate modes

None of them is defined on FreeBSD, for example, and the only other way to make
the code compile would be to define it ourselves.

Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
 fuse/operations.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fuse/operations.c b/fuse/operations.c
index de04ba7b6d72..098613f66f33 100644
--- a/fuse/operations.c
+++ b/fuse/operations.c
@@ -440,6 +440,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t offset,
off_t len,
   if (readonly)
     return -EACCES;
 
+#if defined(FALLOC_FL_PUNCH_HOLE) || defined(FALLOC_FL_ZERO_RANGE)
+# if defined(FALLOC_FL_PUNCH_HOLE)
+
   if (mode & FALLOC_FL_PUNCH_HOLE) {
     if (!nbd_can_trim (nbd.ptr[0]))
       return -EOPNOTSUPP;       /* Trim not supported. */
@@ -448,6 +451,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t offset,
off_t len,
       return 0;
     }
   }
+#endif /*# if defined(FALLOC_FL_PUNCH_HOLE) */
+
+#if defined(FALLOC_FL_ZERO_RANGE)
   /* As of FUSE 35 this is not supported by the kernel module and it
    * always returns EOPNOTSUPP.
    */
@@ -470,7 +476,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t offset,
off_t len,
       return 0;
     }
   }
+#endif /* defined(FALLOC_FL_ZERO_RANGE) */
   else
+#endif /* defined(FALLOC_FL_PUNCH_HOLE) || defined(FALLOC_FL_ZERO_RANGE) */
     return -EOPNOTSUPP;
 }
 
-- 
2.31.1

On Tue, Jun 08, 2021 at 09:53:42AM +0200, Martin Kletzander
wrote:
> None of them is defined on FreeBSD, for example, and the only other way to
make
> the code compile would be to define it ourselves.
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  fuse/operations.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fuse/operations.c b/fuse/operations.c
> index de04ba7b6d72..098613f66f33 100644
> --- a/fuse/operations.c
> +++ b/fuse/operations.c
> @@ -440,6 +440,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t
offset, off_t len,
>    if (readonly)
>      return -EACCES;
>  
> +#if defined(FALLOC_FL_PUNCH_HOLE) || defined(FALLOC_FL_ZERO_RANGE)
> +# if defined(FALLOC_FL_PUNCH_HOLE)
I like this indentation of preprocessor directives...
> +
>    if (mode & FALLOC_FL_PUNCH_HOLE) {
>      if (!nbd_can_trim (nbd.ptr[0]))
>        return -EOPNOTSUPP;       /* Trim not supported. */
> @@ -448,6 +451,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t
offset, off_t len,
>        return 0;
>      }
>    }
> +#endif /*# if defined(FALLOC_FL_PUNCH_HOLE) */
> +
> +#if defined(FALLOC_FL_ZERO_RANGE)
...but you forgot it here
>    /* As of FUSE 35 this is not supported by the kernel module and it
>     * always returns EOPNOTSUPP.
>     */
> @@ -470,7 +476,9 @@ nbdfuse_fallocate (const char *path, int mode, off_t
offset, off_t len,
>        return 0;
>      }
>    }
> +#endif /* defined(FALLOC_FL_ZERO_RANGE) */
...as well as here.
>    else
> +#endif /* defined(FALLOC_FL_PUNCH_HOLE) || defined(FALLOC_FL_ZERO_RANGE)
*/
>      return -EOPNOTSUPP;
>  }
To some extent, it would also be possible to write:

#ifndef FALLOC_FL_PUNCH_HOLE
# define FALLOC_FL_PUNCH_HOLE 0
#endif
#ifndef FALLOC_FL_ZERO_RANGE
# define FALLOC_FL_ZERO_RANGE 0
#endif

static int
nbdfuse_fallocate(...) { ...

  if (mode & FALLOC_FL_PUNCH_HOLE) {
    ...
  }
  else if (mode & FALLOC_FL_ZERO_RANGE) {
    ...
  }
  else
    return -EOPNOTSUPP;
}

for fewer in-function #ifdefs, but that is a style choice, not a
correctness issue, so I won't insist.

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