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Linux 4.16 compat: use correct *_dec_and_test() 

Use refcount_dec_and_test() on 4.16+ kernels, atomic_dec_and_test()
on older kernels.  https://lwn.net/Articles/714974/

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes: #7179
Closes: #7211
This commit is contained in:
Tony Hutter 2018-02-22 09:02:06 -08:00
parent 30ac8de48a
commit e5ba614d05
3 changed files with 26 additions and 1 deletions
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20
config/kernel-acl-refcount.m4 Normal file
View File

@ -0,0 +1,20 @@
dnl #
dnl # 4.16 kernel: check if struct posix_acl acl.a_refcount is a refcount_t.
dnl # It's an atomic_t on older kernels.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_ACL_HAS_REFCOUNT], [
AC_MSG_CHECKING([whether posix_acl has refcount_t])
ZFS_LINUX_TRY_COMPILE([
#include <linux/backing-dev.h>
#include <linux/refcount.h>
#include <linux/posix_acl.h>
],[
struct posix_acl acl;
refcount_t *r __attribute__ ((unused)) = &acl.a_refcount;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ACL_REFCOUNT, 1, [posix_acl has refcount_t])
],[
AC_MSG_RESULT(no)
])
])

1
config/kernel.m4
View File

@ -124,6 +124,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_HAVE_GENERIC_SETXATTR
ZFS_AC_KERNEL_CURRENT_TIME
ZFS_AC_KERNEL_VM_NODE_STAT
ZFS_AC_KERNEL_ACL_HAS_REFCOUNT
AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"

6
include/linux/vfs_compat.h
View File

@ -288,9 +288,13 @@ zpl_posix_acl_release(struct posix_acl *acl)
{
if ((acl == NULL) || (acl == ACL_NOT_CACHED))
return;
#ifdef HAVE_ACL_REFCOUNT
if (refcount_dec_and_test(&acl->a_refcount))
zpl_posix_acl_release_impl(acl);
#else
if (atomic_dec_and_test(&acl->a_refcount))
zpl_posix_acl_release_impl(acl);
#endif
}
#endif /* HAVE_POSIX_ACL_RELEASE */