Linux 4.14 compat: vfs_read & vfs_write

The kernel_read & kernel_write functions have always wrapped the
vfs_read & vfs_write functions respectively.  However, they could
not be used by vn_rdwr() since the offset wasn't passed as a
pointer.  This prevented us from being able to properly update
the file offset.

Linux 4.14 unexported vfs_read & vfs_write but also changed the
signature of kernel_read & kernel_write to provide the needed
functionality.  Use these updated functions when available.

Reviewed-by: Pritam Baral <pritam@pritambaral.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #656 
Closes #667
This commit is contained in:
Brian Behlendorf
2017-11-15 17:19:23 -08:00
committed by GitHub
parent 35a44fcb8d
commit ed19bccfb6
3 changed files with 105 additions and 17 deletions
+60
View File
@@ -52,6 +52,8 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
SPL_AC_KMEM_CACHE_CREATE_USERCOPY
SPL_AC_WAIT_QUEUE_ENTRY_T
SPL_AC_WAIT_QUEUE_HEAD_ENTRY
SPL_AC_KERNEL_WRITE
SPL_AC_KERNEL_READ
])
AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
@@ -1594,3 +1596,61 @@ AC_DEFUN([SPL_AC_WAIT_QUEUE_HEAD_ENTRY], [
AC_MSG_RESULT(no)
])
])
dnl #
dnl # 4.14 API change
dnl # kernel_write() which was introduced in 3.9 was updated to take
dnl # the offset as a pointer which is needed by vn_rdwr().
dnl #
AC_DEFUN([SPL_AC_KERNEL_WRITE], [
AC_MSG_CHECKING([whether kernel_write() takes loff_t pointer])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="-Werror"
SPL_LINUX_TRY_COMPILE([
#include <linux/fs.h>
],[
struct file *file = NULL;
const void *buf = NULL;
size_t count = 0;
loff_t *pos = NULL;
ssize_t ret;
ret = kernel_write(file, buf, count, pos);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_WRITE_PPOS, 1,
[kernel_write() take loff_t pointer])
],[
AC_MSG_RESULT(no)
])
EXTRA_KCFLAGS="$tmp_flags"
])
dnl #
dnl # 4.14 API change
dnl # kernel_read() which has existed for forever was updated to take
dnl # the offset as a pointer which is needed by vn_rdwr().
dnl #
AC_DEFUN([SPL_AC_KERNEL_READ], [
AC_MSG_CHECKING([whether kernel_read() takes loff_t pointer])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="-Werror"
SPL_LINUX_TRY_COMPILE([
#include <linux/fs.h>
],[
struct file *file = NULL;
void *buf = NULL;
size_t count = 0;
loff_t *pos = NULL;
ssize_t ret;
ret = kernel_read(file, buf, count, pos);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_READ_PPOS, 1,
[kernel_read() take loff_t pointer])
],[
AC_MSG_RESULT(no)
])
EXTRA_KCFLAGS="$tmp_flags"
])