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zfs/config/kernel-get-link.m4

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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
2016-01-14 18:25:10 +00:00
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])
],[
Fix config issues: frame size and headers 1. With various (debug and/or tracing?) kernel options enabled it's possible for 'struct inode' and 'struct super_block' to exceed the default frame size, leaving errors like this in config.log: build/conftest.c:116:1: error: the frame size of 1048 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] Fix this by removing the frame size warning for config checks 2. Without the correct headers included, it's possible for declarations to be missed, leaving errors like this in the config.log: build/conftest.c:131:14: error: ‘struct nameidata’ declared inside parameter list [-Werror] Fix this by adding appropriate headers. Note: Both these issues can result in silent config failures because the compile failure is taken to mean "this option is not supported by this kernel" rather than "there's something wrong with the config test". This can lead to something merely annoying (compile failures) to something potentially serious (miscompiled or misused kernel primitives or functions). E.g. the fixes included here resulted in these additional defines in zfs_config.h with linux v4.14.19: Also, drive-by whitespace fixes in config/* files which don't mention "GNU" (those ones look to be imported from elsewhere so leave them alone). Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chris Dunlop <chris@onthe.net.au> Closes #7169
2018-02-15 20:58:23 +00:00
AC_MSG_ERROR(no; please file a bug report)
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
2016-01-14 18:25:10 +00:00
])
])
])
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
])
])
])