4.10 compat - BIO flag changes and others

[bio] The req_op enum was changed to req_opf.  Update the "Linux 4.8 API"
autotools checks to use an int to determine whether the various REQ_OP
values are defined.  This should work properly on kernels >= 4.8.

[bio] bio_set_op_attrs() is now an inline function and can't be detected
with #ifdef.  Add a configure check to determine whether bio_set_op_attrs()
is defined.  Move the local definition of it from vdev_disk.c to
blkdev_compat.h for consistency with other related compability shims.

[bio] The read/write flags and their modifiers, including WRITE_FLUSH,
WRITE_FUA and WRITE_FLUSH_FUA have been removed from fs.h.  Add the new
bio_set_flush() compatibility wrapper to replace VDEV_WRITE_FLUSH_FUA
and set the flags appropriately for each supported kernel version.

[vfs] The generic_readlink() function has been made static.  If .readlink
in inode_operations is NULL, generic_readlink() is used.

[zol typo] Completely unrelated to 4.10 compat, fix a typo in the check
for REQ_OP_SECURE_ERASE so that the proper macro is defined:

    s/HAVE_REQ_OP_SECURE_DISCARD/HAVE_REQ_OP_SECURE_ERASE/

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Chunwei Chen <[email protected]>
Signed-off-by: Tim Chase <[email protected]>
Closes #5499 

3 files changed, 45 insertions, 4 deletions

diff --git a/config/kernel-bio-op.m4 b/config/kernel-bio-op.m4
index b4b699517..5559d6c7f 100644
--- a/config/kernel-bio-op.m4
+++ b/config/kernel-bio-op.m4
@@ -10,7 +10,7 @@ AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_DISCARD], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blk_types.h>
 	],[
-		enum req_op op __attribute__ ((unused)) = REQ_OP_DISCARD;
+		int op __attribute__ ((unused)) = REQ_OP_DISCARD;
 	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_REQ_OP_DISCARD, 1,
@@ -25,10 +25,10 @@ AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_SECURE_ERASE], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blk_types.h>
 	],[
-		enum req_op op __attribute__ ((unused)) = REQ_OP_SECURE_ERASE;
+		int op __attribute__ ((unused)) = REQ_OP_SECURE_ERASE;
 	],[
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_REQ_OP_SECURE_DISCARD, 1,
+		AC_DEFINE(HAVE_REQ_OP_SECURE_ERASE, 1,
 		    [REQ_OP_SECURE_ERASE is defined])
 	],[
 		AC_MSG_RESULT(no)
@@ -41,7 +41,7 @@ AC_DEFUN([ZFS_AC_KERNEL_REQ_OP_FLUSH], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blk_types.h>
 	],[
-		enum req_op op __attribute__ ((unused)) = REQ_OP_FLUSH;
+		int op __attribute__ ((unused)) = REQ_OP_FLUSH;
 	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_REQ_OP_FLUSH, 1,
@@ -65,3 +65,20 @@ AC_DEFUN([ZFS_AC_KERNEL_BIO_BI_OPF], [
 		AC_MSG_RESULT(no)
 	])
 ])
+
+AC_DEFUN([ZFS_AC_KERNEL_HAVE_BIO_SET_OP_ATTRS], [
+	AC_MSG_CHECKING([whether bio_set_op_attrs is available])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/blk_types.h>
+	],[
+		struct bio *bio __attribute__ ((unused)) = NULL;
+
+		bio_set_op_attrs(bio, 0, 0);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_SET_OP_ATTRS, 1,
+		    [bio_set_op_attrs is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
diff --git a/config/kernel-generic_readlink.m4 b/config/kernel-generic_readlink.m4
new file mode 100644
index 000000000..914431de4
--- /dev/null
+++ b/config/kernel-generic_readlink.m4
@@ -0,0 +1,22 @@
+dnl #
+dnl # 4.10 API
+dnl #
+dnl # NULL inode_operations.readlink implies generic_readlink(), which
+dnl # has been made static.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_GENERIC_READLINK_GLOBAL], [
+	AC_MSG_CHECKING([whether generic_readlink is global])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		int i __attribute__ ((unused));
+
+		i = generic_readlink(NULL, NULL, 0);
+	],[
+		AC_MSG_RESULT([yes])
+		AC_DEFINE(HAVE_GENERIC_READLINK, 1,
+		          [generic_readlink is global])
+	],[
+		AC_MSG_RESULT([no])
+	])
+])
diff --git a/config/kernel.m4 b/config/kernel.m4
index 08f544a78..980d2801f 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -37,6 +37,8 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_BLK_QUEUE_HAVE_BLK_PLUG
 	ZFS_AC_KERNEL_GET_DISK_RO
 	ZFS_AC_KERNEL_GET_GENDISK
+	ZFS_AC_KERNEL_HAVE_BIO_SET_OP_ATTRS
+	ZFS_AC_KERNEL_GENERIC_READLINK_GLOBAL
 	ZFS_AC_KERNEL_DISCARD_GRANULARITY
 	ZFS_AC_KERNEL_CONST_XATTR_HANDLER
 	ZFS_AC_KERNEL_XATTR_HANDLER_NAME