Linux 4.4: Do not use splice() 17/12217/5
authorStephan Wiesand <stephan.wiesand@desy.de>
Tue, 8 Mar 2016 13:15:17 +0000 (14:15 +0100)
committerBenjamin Kaduk <kaduk@mit.edu>
Mon, 21 Mar 2016 17:33:08 +0000 (13:33 -0400)
splice() may return -ERESTARTSYS if there are pending signals, and
it's not even clear how this should be dealt with. This potential
problem has been present for a long time, but as of Linux 4.4
(commit c725bfce7968009756ed2836a8cd7ba4dc163011) seems much more
likely to happen.

Until resources are available to fix the code to handle such errors,
avoid the riskier uses of splice().

If there is a default implementation of file_splice_{write,read},
use that; on somewhat older kernels where it is not available,
use the generic version instead.

[kaduk@mit.edu: add test for default_file_splice_write]

Change-Id: Ib4477cdfb2cd0f49f516da75edc3cb9d1a8817dc
Reviewed-on: https://gerrit.openafs.org/12217
Reviewed-by: Chas Williams <3chas3@gmail.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>

acinclude.m4
src/afs/LINUX/osi_fetchstore.c
src/afs/LINUX/osi_vnodeops.c
src/afs/afs_fetchstore.c

index d8d7835..f50099a 100644 (file)
@@ -1076,6 +1076,9 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
                 AC_CHECK_LINUX_FUNC([splice_direct_to_actor],
                                     [#include <linux/splice.h>],
                                     [splice_direct_to_actor(NULL,NULL,NULL);])
+                AC_CHECK_LINUX_FUNC([default_file_splice_read],
+                                    [#include <linux/fs.h>],
+                                    [default_file_splice_read(NULL,NULL,NULL, 0, 0);])
                 AC_CHECK_LINUX_FUNC([svc_addr_in],
                                     [#include <linux/sunrpc/svc.h>],
                                     [svc_addr_in(NULL);])
index 4089bbb..997c1aa 100644 (file)
@@ -38,7 +38,7 @@
 #include "afs/param.h"
 
 #include <linux/fs.h>
-#if defined(HAVE_LINUX_SPLICE_DIRECT_TO_ACTOR)
+#if 0 && defined(HAVE_LINUX_SPLICE_DIRECT_TO_ACTOR)
 # include <linux/splice.h>
 #else
 # include <linux/pipe_fs_i.h>
@@ -47,7 +47,7 @@
 #include "afs/sysincludes.h"
 #include "afsincludes.h"
 
-#if defined(HAVE_LINUX_SPLICE_DIRECT_TO_ACTOR)
+#if 0 && defined(HAVE_LINUX_SPLICE_DIRECT_TO_ACTOR)
 static int
 afs_linux_splice_actor(struct pipe_inode_info *pipe,
                       struct pipe_buffer *buf,
@@ -151,6 +151,7 @@ afs_linux_read_actor(read_descriptor_t *desc, struct page *page,
     return size;
 }
 
+#if 0
 afs_int32
 afs_linux_storeproc(struct storeOps *ops, void *rock, struct dcache *tdc,
                     int *shouldwake, afs_size_t *bytesXferred)
@@ -184,5 +185,6 @@ afs_linux_storeproc(struct storeOps *ops, void *rock, struct dcache *tdc,
 
     return code;
 }
+#endif
 
 #endif
index 6c3a811..89b9520 100644 (file)
@@ -846,7 +846,7 @@ struct file_operations afs_file_fops = {
 #if defined(STRUCT_FILE_OPERATIONS_HAS_SENDFILE)
   .sendfile =   generic_file_sendfile,
 #endif
-#if defined(STRUCT_FILE_OPERATIONS_HAS_SPLICE)
+#if defined(STRUCT_FILE_OPERATIONS_HAS_SPLICE) && !defined(HAVE_LINUX_DEFAULT_FILE_SPLICE_READ)
 # if defined(HAVE_LINUX_ITER_FILE_SPLICE_WRITE)
   .splice_write = iter_file_splice_write,
 # else
index f65f40c..c75da94 100644 (file)
@@ -326,7 +326,7 @@ struct storeOps rxfs_storeUfsOps = {
     .padd =    rxfs_storePadd,
     .close =   rxfs_storeClose,
     .destroy = rxfs_storeDestroy,
-#ifdef AFS_LINUX26_ENV
+#if 0 && defined(AFS_LINUX26_ENV)
     .storeproc = afs_linux_storeproc
 #else
     .storeproc = afs_GenericStoreProc