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Linux 4.5 compat: get_link() / put_link()

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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
config/kernel-follow-link-nameidata.m4
View File

@ -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
config/kernel-get-link.m4 Normal file
View File

@ -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
config/kernel-put-link-nameidata.m4
View File

@ -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
config/kernel-put-link.m4 Normal file
View File

@ -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)
])
])
])
])

2
config/kernel.m4
View File

@ -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

137
module/zfs/zpl_inode.c
View File

@ -367,26 +367,42 @@ zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
return (error);
}
#ifdef HAVE_FOLLOW_LINK_NAMEIDATA
static void *
zpl_follow_link(struct dentry *dentry, struct nameidata *nd)
#else
const char *
zpl_follow_link(struct dentry *dentry, void **symlink_cookie)
#endif
#if defined(HAVE_PUT_LINK_COOKIE)
static void
zpl_put_link(struct inode *unused, void *cookie)
{
kmem_free(cookie, MAXPATHLEN);
}
#elif defined(HAVE_PUT_LINK_NAMEIDATA)
static void
zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
const char *link = nd_get_link(nd);
if (!IS_ERR(link))
kmem_free(link, MAXPATHLEN);
}
#elif defined(HAVE_PUT_LINK_DELAYED)
static void
zpl_put_link(void *ptr)
{
kmem_free(ptr, MAXPATHLEN);
}
#endif
static int
zpl_get_link_common(struct dentry *dentry, struct inode *ip, char **link)
{
fstrans_cookie_t cookie;
cred_t *cr = CRED();
struct inode *ip = dentry->d_inode;
struct iovec iov;
uio_t uio;
char *link;
int error;
fstrans_cookie_t cookie;
crhold(cr);
*link = NULL;
iov.iov_len = MAXPATHLEN;
iov.iov_base = link = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
iov.iov_base = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
@ -397,41 +413,78 @@ zpl_follow_link(struct dentry *dentry, void **symlink_cookie)
cookie = spl_fstrans_mark();
error = -zfs_readlink(ip, &uio, cr);
spl_fstrans_unmark(cookie);
if (error)
kmem_free(link, MAXPATHLEN);
crfree(cr);
#ifdef HAVE_FOLLOW_LINK_NAMEIDATA
if (error)
kmem_free(iov.iov_base, MAXPATHLEN);
else
*link = iov.iov_base;
return (error);
}
#if defined(HAVE_GET_LINK_DELAYED)
const char *
zpl_get_link(struct dentry *dentry, struct inode *inode,
struct delayed_call *done)
{
char *link = NULL;
int error;
if (!dentry)
return (ERR_PTR(-ECHILD));
error = zpl_get_link_common(dentry, inode, &link);
if (error)
return (ERR_PTR(error));
set_delayed_call(done, zpl_put_link, link);
return (link);
}
#elif defined(HAVE_GET_LINK_COOKIE)
const char *
zpl_get_link(struct dentry *dentry, struct inode *inode, void **cookie)
{
char *link = NULL;
int error;
if (!dentry)
return (ERR_PTR(-ECHILD));
error = zpl_get_link_common(dentry, inode, &link);
if (error)
return (ERR_PTR(error));
return (*cookie = link);
}
#elif defined(HAVE_FOLLOW_LINK_COOKIE)
const char *
zpl_follow_link(struct dentry *dentry, void **cookie)
{
char *link = NULL;
int error;
error = zpl_get_link_common(dentry, dentry->d_inode, &link);
if (error)
return (ERR_PTR(error));
return (*cookie = link);
}
#elif defined(HAVE_FOLLOW_LINK_NAMEIDATA)
static void *
zpl_follow_link(struct dentry *dentry, struct nameidata *nd)
{
char *link = NULL;
int error;
error = zpl_get_link_common(dentry, dentry->d_inode, &link);
if (error)
nd_set_link(nd, ERR_PTR(error));
else
nd_set_link(nd, link);
return (NULL);
#else
if (error)
return (ERR_PTR(error));
else
return (*symlink_cookie = link);
#endif
}
#ifdef HAVE_PUT_LINK_NAMEIDATA
static void
zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
const char *link = nd_get_link(nd);
if (!IS_ERR(link))
kmem_free(link, MAXPATHLEN);
}
#else
static void
zpl_put_link(struct inode *unused, void *symlink_cookie)
{
kmem_free(symlink_cookie, MAXPATHLEN);
}
#endif
@ -619,8 +672,14 @@ const struct inode_operations zpl_dir_inode_operations = {
const struct inode_operations zpl_symlink_inode_operations = {
.readlink = generic_readlink,
#if defined(HAVE_GET_LINK_DELAYED) || defined(HAVE_GET_LINK_COOKIE)
.get_link = zpl_get_link,
#elif defined(HAVE_FOLLOW_LINK_COOKIE) || defined(HAVE_FOLLOW_LINK_NAMEIDATA)
.follow_link = zpl_follow_link,
#endif
#if defined(HAVE_PUT_LINK_COOKIE) || defined(HAVE_PUT_LINK_NAMEIDATA)
.put_link = zpl_put_link,
#endif
.setattr = zpl_setattr,
.getattr = zpl_getattr,
.setxattr = generic_setxattr,