Linux 4.4: Do not use splice()

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>

diff --git a/acinclude.m4 b/acinclude.m4
index d8d7835e79a9b1c4e2fc6151264b4076ab03809d..f50099aba23fb60b7e9e726debc69d17d36e8fe1 100644 (file)
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -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);])

diff --git a/src/afs/LINUX/osi_fetchstore.c b/src/afs/LINUX/osi_fetchstore.c
index 4089bbbeee539b5153d7bfa0a2c633287db0740d..997c1aa2e68cab257ae08d6ec4cab6485579e20b 100644 (file)
--- a/src/afs/LINUX/osi_fetchstore.c
+++ b/src/afs/LINUX/osi_fetchstore.c
@@ -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

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 6c3a811d4f0efea5373d7cd2646871430daaf295..89b9520bb223c7bfa5f684d9cc4a93283b2fb6e1 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -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

diff --git a/src/afs/afs_fetchstore.c b/src/afs/afs_fetchstore.c
index f65f40cd4e440c9478714c6840c71dcd92d3b156..c75da94356ce66ac246e292389a0ff4dba97be80 100644 (file)
--- a/src/afs/afs_fetchstore.c
+++ b/src/afs/afs_fetchstore.c
@@ -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