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From 8c11a97ec0991800c12311a123134f8b5fd59f5e Mon Sep 17 00:00:00 2001
From: Damien Diederen <ddiederen@sinenomine.net>
Date: Mon, 18 Sep 2017 12:18:39 +0200
Subject: [PATCH 3/3] Linux: Use kernel_read/kernel_write when __vfs variants
are unavailable
We hide the uses of set_fs/get_fs behind a macro, as those functions
are likely to soon become unavailable:
> Christoph Hellwig suggested removing all calls outside of the core
> filesystem and architecture code; Andy Lutomirski went one step
> further and said they should all go.
https://lwn.net/Articles/722267/
Reviewed-on: https://gerrit.openafs.org/12729
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 5ee516b3789d3545f3d78fb3aba2480308359945)
Reviewed-on: https://gerrit.openafs.org/12737
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit d93f80622370f50d7bce5c5b00cd062f15ee9eba)
Change-Id: Ib4515c858d0a06d3706ec7de212c35551d3e7240
---
acinclude.m4 | 3 +++
src/afs/LINUX/osi_compat.h | 12 ++++++++++++
src/afs/LINUX/osi_file.c | 6 ++++++
src/afs/LINUX/osi_vnodeops.c | 2 +-
4 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/acinclude.m4 b/acinclude.m4
index 8353ca597..94b943622 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -942,6 +942,9 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
AC_CHECK_LINUX_FUNC([__vfs_write],
[#include <linux/fs.h>],
[__vfs_write(NULL, NULL, 0, NULL);])
+ AC_CHECK_LINUX_FUNC([kernel_write],
+ [#include <linux/fs.h>],
+ [kernel_write(NULL, NULL, 0, NULL);])
AC_CHECK_LINUX_FUNC([bdi_init],
[#include <linux/backing-dev.h>],
[bdi_init(NULL);])
diff --git a/src/afs/LINUX/osi_compat.h b/src/afs/LINUX/osi_compat.h
index 9ebe9c178..9871535f0 100644
--- a/src/afs/LINUX/osi_compat.h
+++ b/src/afs/LINUX/osi_compat.h
@@ -592,11 +592,21 @@ afs_d_invalidate(struct dentry *dp)
#endif
}
+#if defined(HAVE_LINUX___VFS_WRITE)
+# define AFS_FILE_NEEDS_SET_FS 1
+#elif defined(HAVE_LINUX_KERNEL_WRITE)
+/* #undef AFS_FILE_NEEDS_SET_FS */
+#else
+# define AFS_FILE_NEEDS_SET_FS 1
+#endif
+
static inline int
afs_file_read(struct file *filp, char __user *buf, size_t len, loff_t *pos)
{
#if defined(HAVE_LINUX___VFS_WRITE)
return __vfs_read(filp, buf, len, pos);
+#elif defined(HAVE_LINUX_KERNEL_WRITE)
+ return kernel_read(filp, buf, len, pos);
#else
return filp->f_op->read(filp, buf, len, pos);
#endif
@@ -607,6 +617,8 @@ afs_file_write(struct file *filp, char __user *buf, size_t len, loff_t *pos)
{
#if defined(HAVE_LINUX___VFS_WRITE)
return __vfs_write(filp, buf, len, pos);
+#elif defined(HAVE_LINUX_KERNEL_WRITE)
+ return kernel_write(filp, buf, len, pos);
#else
return filp->f_op->write(filp, buf, len, pos);
#endif
diff --git a/src/afs/LINUX/osi_file.c b/src/afs/LINUX/osi_file.c
index f889fd16b..a028ee740 100644
--- a/src/afs/LINUX/osi_file.c
+++ b/src/afs/LINUX/osi_file.c
@@ -357,7 +357,9 @@ int
osi_rdwr(struct osi_file *osifile, struct uio *uiop, int rw)
{
struct file *filp = osifile->filp;
+#ifdef AFS_FILE_NEEDS_SET_FS
mm_segment_t old_fs = {0};
+#endif /* AFS_FILE_NEEDS_SET_FS */
int code = 0;
struct iovec *iov;
size_t count;
@@ -367,11 +369,13 @@ osi_rdwr(struct osi_file *osifile, struct uio *uiop, int rw)
savelim = current->TASK_STRUCT_RLIM[RLIMIT_FSIZE].rlim_cur;
current->TASK_STRUCT_RLIM[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
+#ifdef AFS_FILE_NEEDS_SET_FS
if (uiop->uio_seg == AFS_UIOSYS) {
/* Switch into user space */
old_fs = get_fs();
set_fs(get_ds());
}
+#endif /* AFS_FILE_NEEDS_SET_FS */
while (code == 0 && uiop->uio_resid > 0 && uiop->uio_iovcnt > 0) {
iov = uiop->uio_iov;
@@ -408,10 +412,12 @@ osi_rdwr(struct osi_file *osifile, struct uio *uiop, int rw)
code = 0;
}
+#ifdef AFS_FILE_NEEDS_SET_FS
if (uiop->uio_seg == AFS_UIOSYS) {
/* Switch back into kernel space */
set_fs(old_fs);
}
+#endif /* AFS_FILE_NEEDS_SET_FS */
current->TASK_STRUCT_RLIM[RLIMIT_FSIZE].rlim_cur = savelim;
diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 3d9d71791..051452b34 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -807,7 +807,7 @@ struct file_operations afs_file_fops = {
#ifdef STRUCT_FILE_OPERATIONS_HAS_READ_ITER
.read_iter = afs_linux_read_iter,
.write_iter = afs_linux_write_iter,
-# if !defined(HAVE_LINUX___VFS_WRITE)
+# if !defined(HAVE_LINUX___VFS_WRITE) && !defined(HAVE_LINUX_KERNEL_WRITE)
.read = new_sync_read,
.write = new_sync_write,
# endif
--
2.15.0
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