1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
2 From: Tony Hutter <hutter2@llnl.gov>
3 Date: Thu, 22 Feb 2018 09:02:06 -0800
4 Subject: [PATCH] Linux 4.16 compat: use correct *_dec_and_test()
6 Content-Type: text/plain; charset=UTF-8
7 Content-Transfer-Encoding: 8bit
9 Use refcount_dec_and_test() on 4.16+ kernels, atomic_dec_and_test()
10 on older kernels. https://lwn.net/Articles/714974/
12 Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
13 Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
14 Signed-off-by: Tony Hutter <hutter2@llnl.gov>
17 (cherry picked from commit e5ba614d05bde1e98ba46d5b75cf6b8a0701c2ca)
18 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
20 include/linux/vfs_compat.h | 6 +++++-
21 config/kernel-acl-refcount.m4 | 20 ++++++++++++++++++++
22 config/kernel.m4 | 1 +
23 3 files changed, 26 insertions(+), 1 deletion(-)
24 create mode 100644 config/kernel-acl-refcount.m4
26 diff --git a/include/linux/vfs_compat.h b/include/linux/vfs_compat.h
27 index 7fcf3c055..6347268af 100644
28 --- a/include/linux/vfs_compat.h
29 +++ b/include/linux/vfs_compat.h
30 @@ -288,9 +288,13 @@ zpl_posix_acl_release(struct posix_acl *acl)
32 if ((acl == NULL) || (acl == ACL_NOT_CACHED))
35 +#ifdef HAVE_ACL_REFCOUNT
36 + if (refcount_dec_and_test(&acl->a_refcount))
37 + zpl_posix_acl_release_impl(acl);
39 if (atomic_dec_and_test(&acl->a_refcount))
40 zpl_posix_acl_release_impl(acl);
43 #endif /* HAVE_POSIX_ACL_RELEASE */
45 diff --git a/config/kernel-acl-refcount.m4 b/config/kernel-acl-refcount.m4
47 index 000000000..43e3c442d
49 +++ b/config/kernel-acl-refcount.m4
52 +dnl # 4.16 kernel: check if struct posix_acl acl.a_refcount is a refcount_t.
53 +dnl # It's an atomic_t on older kernels.
55 +AC_DEFUN([ZFS_AC_KERNEL_ACL_HAS_REFCOUNT], [
56 + AC_MSG_CHECKING([whether posix_acl has refcount_t])
57 + ZFS_LINUX_TRY_COMPILE([
58 + #include <linux/backing-dev.h>
59 + #include <linux/refcount.h>
60 + #include <linux/posix_acl.h>
62 + struct posix_acl acl;
63 + refcount_t *r __attribute__ ((unused)) = &acl.a_refcount;
66 + AC_DEFINE(HAVE_ACL_REFCOUNT, 1, [posix_acl has refcount_t])
71 diff --git a/config/kernel.m4 b/config/kernel.m4
72 index d4a84b2b2..7bb86a96e 100644
73 --- a/config/kernel.m4
74 +++ b/config/kernel.m4
75 @@ -124,6 +124,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
76 ZFS_AC_KERNEL_HAVE_GENERIC_SETXATTR
77 ZFS_AC_KERNEL_CURRENT_TIME
78 ZFS_AC_KERNEL_VM_NODE_STAT
79 + ZFS_AC_KERNEL_ACL_HAS_REFCOUNT
81 AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
82 KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"