zfs-patches/0037-Linux-4.16-compat-use-correct-_dec_and_test.patch

   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()
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Use refcount_dec_and_test() on 4.16+ kernels, atomic_dec_and_test()
  10 on older kernels.  https://lwn.net/Articles/714974/
  11
  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>
  15 Closes: #7179
  16 Closes: #7211
  17 (cherry picked from commit e5ba614d05bde1e98ba46d5b75cf6b8a0701c2ca)
  18 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  19 ---
  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
  25
  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)
  31  {
  32         if ((acl == NULL) || (acl == ACL_NOT_CACHED))
  33                 return;
  34 -
  35 +#ifdef HAVE_ACL_REFCOUNT
  36 +       if (refcount_dec_and_test(&acl->a_refcount))
  37 +               zpl_posix_acl_release_impl(acl);
  38 +#else
  39         if (atomic_dec_and_test(&acl->a_refcount))
  40                 zpl_posix_acl_release_impl(acl);
  41 +#endif
  42  }
  43  #endif /* HAVE_POSIX_ACL_RELEASE */
  44
  45 diff --git a/config/kernel-acl-refcount.m4 b/config/kernel-acl-refcount.m4
  46 new file mode 100644
  47 index 000000000..43e3c442d
  48 --- /dev/null
  49 +++ b/config/kernel-acl-refcount.m4
  50 @@ -0,0 +1,20 @@
  51 +dnl #
  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.
  54 +dnl #
  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>
  61 +       ],[
  62 +               struct posix_acl acl;
  63 +               refcount_t *r __attribute__ ((unused)) = &acl.a_refcount;
  64 +       ],[
  65 +               AC_MSG_RESULT(yes)
  66 +               AC_DEFINE(HAVE_ACL_REFCOUNT, 1, [posix_acl has refcount_t])
  67 +       ],[
  68 +               AC_MSG_RESULT(no)
  69 +       ])
  70 +])
  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
  80
  81         AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
  82                 KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"
  83 --
  84 2.14.2
  85