Linux: Test for __vfs_write rather than __vfs_read

The following commit:

    commit eb031849d52e61d24ba54e9d27553189ff328174
    Author: Christoph Hellwig <hch@lst.de>
    Date:   Fri Sep 1 17:39:23 2017 +0200

        fs: unexport __vfs_read/__vfs_write

unexports both __vfs_read and __vfs_write, but keeps the former in
fs.h--as it is is still being used by another part of the tree.

This situation results in a false positive in our Autoconf check,
which does not see the export statements, and ends up marking the
corresponding API as available.

That, in turn, causes some code which assumes symmetry with
__vfs_write to fail to compile.

Switch to testing for __vfs_write, which correctly marks the API as
unavailable.

Change-Id: I392f2b17b4de7bd81d549c84e6f7b5ef05e1b999
Reviewed-on: https://gerrit.openafs.org/12728
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>

diff --git a/acinclude.m4 b/acinclude.m4
index 0d28d44..162a3e9 100644 (file)
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1001,9 +1001,9 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
 
                 dnl Function existence checks
 
-                AC_CHECK_LINUX_FUNC([__vfs_read],
+                AC_CHECK_LINUX_FUNC([__vfs_write],
                                     [#include <linux/fs.h>],
-                                    [__vfs_read(NULL, NULL, 0, NULL);])
+                                    [__vfs_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 14762fa..13915b9 100644 (file)
--- a/src/afs/LINUX/osi_compat.h
+++ b/src/afs/LINUX/osi_compat.h
@@ -648,7 +648,7 @@ afs_d_invalidate(struct dentry *dp)
 static inline int
 afs_file_read(struct file *filp, char __user *buf, size_t len, loff_t *pos)
 {
-#if defined(HAVE_LINUX___VFS_READ)
+#if defined(HAVE_LINUX___VFS_WRITE)
     return __vfs_read(filp, buf, len, pos);
 #else
     return filp->f_op->read(filp, buf, len, pos);
@@ -658,7 +658,7 @@ afs_file_read(struct file *filp, char __user *buf, size_t len, loff_t *pos)
 static inline int
 afs_file_write(struct file *filp, char __user *buf, size_t len, loff_t *pos)
 {
-#if defined(HAVE_LINUX___VFS_READ)
+#if defined(HAVE_LINUX___VFS_WRITE)
     return __vfs_write(filp, buf, len, pos);
 #else
     return filp->f_op->write(filp, buf, len, pos);

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index d058545..d935cf5 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -825,7 +825,7 @@ 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_READ)
+# if !defined(HAVE_LINUX___VFS_WRITE)
   .read =      new_sync_read,
   .write =     new_sync_write,
 # endif