Linux 4.5 compat: get_link() / put_link()

The follow_link() interface was retired in favor of get_link().
In the process of phasing in get_link() the Linux kernel went
through two different versions.  The first of which depended
on put_link() and the final version on a delayed done function.

- Improved configure checks for .follow_link, .get_link, .put_link.
  - Interfaces checked from newest to oldest.
  - Strict checking for each possible known interface.
  - Configure fails when no known interface is available.

- Both versions .get_link are detected and supported as well
  two previous versions of .follow_link.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Issue #4228
This commit is contained in:
Brian Behlendorf
2016-01-14 13:25:10 -05:00
parent bc89ac8479
commit beeed4596b
6 changed files with 259 additions and 87 deletions
-24
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@@ -1,24 +0,0 @@
dnl #
dnl # 4.2 API change
dnl # This kernel retired the nameidata structure which forced the
dnl # restructuring of the follow_link() prototype and how it is called.
dnl # We check for the new interface rather than detecting the old one.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_FOLLOW_LINK], [
AC_MSG_CHECKING([whether iops->follow_link() passes nameidata])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
const char *follow_link(struct dentry *de, void **cookie)
{ return "symlink"; }
static struct inode_operations iops __attribute__ ((unused)) = {
.follow_link = follow_link,
};
],[
],[
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FOLLOW_LINK_NAMEIDATA, 1,
[iops->follow_link() nameidata])
])
])
+100
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@@ -0,0 +1,100 @@
dnl #
dnl # Supported get_link() interfaces checked newest to oldest.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_FOLLOW_LINK], [
dnl #
dnl # 4.2 API change
dnl # - This kernel retired the nameidata structure.
dnl #
AC_MSG_CHECKING([whether iops->follow_link() passes cookie])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
const char *follow_link(struct dentry *de,
void **cookie) { return "symlink"; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.follow_link = follow_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FOLLOW_LINK_COOKIE, 1,
[iops->follow_link() cookie])
],[
dnl #
dnl # 2.6.32 API
dnl #
AC_MSG_RESULT(no)
AC_MSG_CHECKING(
[whether iops->follow_link() passes nameidata])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
void *follow_link(struct dentry *de, struct
nameidata *nd) { return (void *)NULL; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.follow_link = follow_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FOLLOW_LINK_NAMEIDATA, 1,
[iops->follow_link() nameidata])
],[
AC_MSG_ERROR(no; please file a bug report)
])
])
])
AC_DEFUN([ZFS_AC_KERNEL_GET_LINK], [
dnl #
dnl # 4.5 API change
dnl # The get_link interface has added a delayed done call and
dnl # used it to retire the put_link() interface.
dnl #
AC_MSG_CHECKING([whether iops->get_link() passes delayed])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
const char *get_link(struct dentry *de, struct inode *ip,
struct delayed_call *done) { return "symlink"; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.get_link = get_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_GET_LINK_DELAYED, 1,
[iops->get_link() delayed])
],[
dnl #
dnl # 4.5 API change
dnl # The follow_link() interface has been replaced by
dnl # get_link() which behaves the same as before except:
dnl # - An inode is passed as a separate argument
dnl # - When called in RCU mode a NULL dentry is passed.
dnl #
AC_MSG_RESULT(no)
AC_MSG_CHECKING([whether iops->get_link() passes cookie])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
const char *get_link(struct dentry *de, struct
inode *ip, void **cookie) { return "symlink"; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.get_link = get_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_GET_LINK_COOKIE, 1,
[iops->get_link() cookie])
],[
dnl #
dnl # Check for the follow_link APIs.
dnl #
AC_MSG_RESULT(no)
ZFS_AC_KERNEL_FOLLOW_LINK
])
])
])
-23
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@@ -1,23 +0,0 @@
dnl #
dnl # 4.2 API change
dnl # This kernel retired the nameidata structure which forced the
dnl # restructuring of the put_link() prototype and how it is called.
dnl # We check for the new interface rather than detecting the old one.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_PUT_LINK], [
AC_MSG_CHECKING([whether iops->put_link() passes nameidata])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
void put_link(struct inode *ip, void *cookie) { return; }
static struct inode_operations iops __attribute__ ((unused)) = {
.put_link = put_link,
};
],[
],[
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_PUT_LINK_NAMEIDATA, 1,
[iops->put_link() nameidata])
])
])
+60
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@@ -0,0 +1,60 @@
dnl #
dnl # Supported symlink APIs
dnl #
AC_DEFUN([ZFS_AC_KERNEL_PUT_LINK], [
dnl #
dnl # 4.5 API change
dnl # get_link() uses delayed done, there is no put_link() interface.
dnl #
ZFS_LINUX_TRY_COMPILE([
#if !defined(HAVE_GET_LINK_DELAYED)
#error "Expecting get_link() delayed done"
#endif
],[
],[
AC_DEFINE(HAVE_PUT_LINK_DELAYED, 1, [iops->put_link() delayed])
],[
dnl #
dnl # 4.2 API change
dnl # This kernel retired the nameidata structure.
dnl #
AC_MSG_CHECKING([whether iops->put_link() passes cookie])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
void put_link(struct inode *ip, void *cookie)
{ return; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.put_link = put_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_PUT_LINK_COOKIE, 1,
[iops->put_link() cookie])
],[
dnl #
dnl # 2.6.32 API
dnl #
AC_MSG_RESULT(no)
AC_MSG_CHECKING(
[whether iops->put_link() passes nameidata])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
void put_link(struct dentry *de, struct
nameidata *nd, void *ptr) { return; }
static struct inode_operations
iops __attribute__ ((unused)) = {
.put_link = put_link,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_PUT_LINK_NAMEIDATA, 1,
[iops->put_link() nameidata])
],[
AC_MSG_ERROR(no; please file a bug report)
])
])
])
])
+1 -1
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@@ -58,7 +58,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_MKDIR_UMODE_T
ZFS_AC_KERNEL_LOOKUP_NAMEIDATA
ZFS_AC_KERNEL_CREATE_NAMEIDATA
ZFS_AC_KERNEL_FOLLOW_LINK
ZFS_AC_KERNEL_GET_LINK
ZFS_AC_KERNEL_PUT_LINK
ZFS_AC_KERNEL_TRUNCATE_RANGE
ZFS_AC_KERNEL_AUTOMOUNT