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Linux 4.14 compat: vfs_read/vfs_write => kernel_read/kernel_write #666

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Linux 4.14 compat: vfs_read/vfs_write => kernel_read/kernel_write #666

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16 changes: 16 additions & 0 deletions config/spl-build.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ 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
])

AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
Expand Down Expand Up @@ -1594,3 +1595,18 @@ AC_DEFUN([SPL_AC_WAIT_QUEUE_HEAD_ENTRY], [
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 3.9 API introduction
dnl # kernel_write() as an improvement upon (and wrapper around) vfs_write()
dnl #
AC_DEFUN([SPL_AC_KERNEL_WRITE], [
AC_MSG_CHECKING([whether kernel_write() is exported])
SPL_CHECK_SYMBOL_EXPORT([kernel_write],
[],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_WRITE, 1, [yes])
],[
AC_MSG_RESULT(no)
])
])
48 changes: 38 additions & 10 deletions module/spl/spl-vnode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <sys/kmem_cache.h>
#include <linux/falloc.h>
#include <linux/file_compat.h>
#include <linux/version.h>

vnode_t *rootdir = (vnode_t *)0xabcd1234;
EXPORT_SYMBOL(rootdir);
Expand Down Expand Up @@ -207,12 +208,46 @@ vn_openat(const char *path, uio_seg_t seg, int flags, int mode,
} /* vn_openat() */
EXPORT_SYMBOL(vn_openat);

static ssize_t
spl_kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
{
#if defined(HAVE_KERNEL_WRITE)

#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,14,0)
return kernel_write(file, buf, count, pos);
#else
return kernel_write(file, (char *)buf, count, *pos);
#endif /* LINUX_VERSION_CODE */

#else // We have to use the older vfs_write API
mm_segment_t old_fs;
ssize_t ret;

old_fs = get_fs();
set_fs(get_ds());
/* The cast to a user pointer is valid due to the set_fs() */
ret = vfs_write(file, (__force const char __user *)buf, count, pos);
set_fs(old_fs);

return ret;
#endif /* HAVE_KERNEL_WRITE */
}

static ssize_t
spl_kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,14,0)
return kernel_read(file, buf, count, pos);
#else /* kernel_read had a different API before 4.14.0, but it's been available since the earliest git release of Linux */
return kernel_read(file, *pos, (char *)buf, count);
#endif
}

int
vn_rdwr(uio_rw_t uio, vnode_t *vp, void *addr, ssize_t len, offset_t off,
uio_seg_t seg, int ioflag, rlim64_t x2, void *x3, ssize_t *residp)
{
loff_t offset;
mm_segment_t saved_fs;
struct file *fp;
int rc;

Expand All @@ -228,18 +263,11 @@ vn_rdwr(uio_rw_t uio, vnode_t *vp, void *addr, ssize_t len, offset_t off,
if (ioflag & FAPPEND)
offset = fp->f_pos;

/* Writable user data segment must be briefly increased for this
* process so we can use the user space read call paths to write
* in to memory allocated by the kernel. */
saved_fs = get_fs();
set_fs(get_ds());

if (uio & UIO_WRITE)
rc = vfs_write(fp, addr, len, &offset);
rc = spl_kernel_write(fp, addr, len, &offset);
else
rc = vfs_read(fp, addr, len, &offset);
rc = spl_kernel_read(fp, addr, len, &offset);

set_fs(saved_fs);
fp->f_pos = offset;

if (rc < 0)
Expand Down