freebsd-dev/config/kernel-vfs-iterate.m4
Brian Behlendorf 9464b9591e
RHEL 7.5 compat: FMODE_KABI_ITERATE
As of RHEL 7.5 the mainline fops.iterate() method was added to
the file_operations structure and is correctly detected by the
configure script.

Normally this is what we want, but in order to maintain KABI
compatibility the RHEL change additionally does the following:

* Requires that callers intending to use this extended interface
  set the FMODE_KABI_ITERATE flag on the file structure when
  opening the directory.
* Adds the fops.iterate() method to the end of the structure,
  without removing fops.readdir().

This change updates the configure check to ignore the RHEL 7.5+
variant of fops.iterate() when detected.  Instead fallback to
the fops.readdir() interface which will be available.

Finally, add the 'zpl_' prefix to the directory context wrappers
to avoid colliding with the kernel provided symbols when both
the fops.iterate() and fops.readdir() are provided by the kernel.

Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7460 
Closes #7463
2018-05-02 15:01:24 -07:00

76 lines
1.9 KiB
Plaintext

AC_DEFUN([ZFS_AC_KERNEL_VFS_ITERATE], [
dnl #
dnl # 4.7 API change
dnl #
AC_MSG_CHECKING([whether fops->iterate_shared() is available])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
int iterate(struct file *filp, struct dir_context * context)
{ return 0; }
static const struct file_operations fops
__attribute__ ((unused)) = {
.iterate_shared = iterate,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_VFS_ITERATE_SHARED, 1,
[fops->iterate_shared() is available])
],[
AC_MSG_RESULT(no)
dnl #
dnl # 3.11 API change
dnl #
dnl # RHEL 7.5 compatibility; the fops.iterate() method was
dnl # added to the file_operations structure but in order to
dnl # maintain KABI compatibility all callers must set
dnl # FMODE_KABI_ITERATE which is checked in iterate_dir().
dnl # When detected ignore this interface and fallback to
dnl # to using fops.readdir() to retain KABI compatibility.
dnl #
AC_MSG_CHECKING([whether fops->iterate() is available])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
int iterate(struct file *filp,
struct dir_context *context) { return 0; }
static const struct file_operations fops
__attribute__ ((unused)) = {
.iterate = iterate,
};
#if defined(FMODE_KABI_ITERATE)
#error "RHEL 7.5, FMODE_KABI_ITERATE interface"
#endif
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_VFS_ITERATE, 1,
[fops->iterate() is available])
],[
AC_MSG_RESULT(no)
AC_MSG_CHECKING([whether fops->readdir() is available])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
int readdir(struct file *filp, void *entry,
filldir_t func) { return 0; }
static const struct file_operations fops
__attribute__ ((unused)) = {
.readdir = readdir,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_VFS_READDIR, 1,
[fops->readdir() is available])
],[
AC_MSG_ERROR(no; file a bug report with ZoL)
])
])
])
])