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Linux 4.18.0-257.el8 compat: blk_alloc_queue() 

The CentOS stream 4.18.0-257 kernel appears to have backported
the Linux 5.9 change to make_request_fn and the associated API.
To maintain weak modules compatibility the original symbol was
retained and the new interface blk_alloc_queue_rh() was added.

Unfortunately, blk_alloc_queue() was replaced in the blkdev.h
header by blk_alloc_queue_bh() so there doesn't seem to be a way
to build new kmods against the old interfces.  Even though they
appear to still be available for weak module binding.

To accommodate this a configure check is added for the new _rh()
variant of the function and used if available.  If compatibility
code gets added to the kernel for the original blk_alloc_queue()
interface this should be fine.  OpenZFS will simply continue to
prefer the new interface and only fallback to blk_alloc_queue()
when blk_alloc_queue_rh() isn't available.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11374
This commit is contained in:
Brian Behlendorf 2020-12-21 10:11:56 -08:00
parent 7a7e101437
commit 03ad94a3b2
2 changed files with 58 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
config/kernel-make-request-fn.m4
View File

@ -27,6 +27,15 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_MAKE_REQUEST_FN], [
q = blk_alloc_queue(make_request, NUMA_NO_NODE);
])
ZFS_LINUX_TEST_SRC([blk_alloc_queue_request_fn_rh], [
#include <linux/blkdev.h>
blk_qc_t make_request(struct request_queue *q,
struct bio *bio) { return (BLK_QC_T_NONE); }
],[
struct request_queue *q __attribute__ ((unused));
q = blk_alloc_queue_rh(make_request, NUMA_NO_NODE);
])
ZFS_LINUX_TEST_SRC([block_device_operations_submit_bio], [
#include <linux/blkdev.h>
],[
@ -48,6 +57,8 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
AC_DEFINE(HAVE_SUBMIT_BIO_IN_BLOCK_DEVICE_OPERATIONS, 1,
[submit_bio is member of struct block_device_operations])
],[
AC_MSG_RESULT(no)
dnl # Checked as part of the blk_alloc_queue_request_fn test
dnl #
dnl # Linux 5.7 API Change
@ -55,6 +66,9 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
dnl #
AC_MSG_CHECKING([whether blk_alloc_queue() expects request function])
ZFS_LINUX_TEST_RESULT([blk_alloc_queue_request_fn], [
AC_MSG_RESULT(yes)
dnl # This is currently always the case.
AC_MSG_CHECKING([whether make_request_fn() returns blk_qc_t])
AC_MSG_RESULT(yes)
@ -65,11 +79,35 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
AC_DEFINE(HAVE_MAKE_REQUEST_FN_RET_QC, 1,
[Noting that make_request_fn() returns blk_qc_t])
],[
dnl #
dnl # CentOS Stream 4.18.0-257 API Change
dnl # The Linux 5.7 blk_alloc_queue() change was back-
dnl # ported and the symbol renamed blk_alloc_queue_rh().
dnl # As of this kernel version they're not providing
dnl # any compatibility code in the kernel for this.
dnl #
ZFS_LINUX_TEST_RESULT([blk_alloc_queue_request_fn_rh], [
AC_MSG_RESULT(yes)
dnl # This is currently always the case.
AC_MSG_CHECKING([whether make_request_fn_rh() returns blk_qc_t])
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_ALLOC_QUEUE_REQUEST_FN_RH, 1,
[blk_alloc_queue_rh() expects request function])
AC_DEFINE(MAKE_REQUEST_FN_RET, blk_qc_t,
[make_request_fn() return type])
AC_DEFINE(HAVE_MAKE_REQUEST_FN_RET_QC, 1,
[Noting that make_request_fn() returns blk_qc_t])
],[
AC_MSG_RESULT(no)
dnl #
dnl # Linux 3.2 API Change
dnl # make_request_fn returns void.
dnl #
AC_MSG_CHECKING([whether make_request_fn() returns void])
AC_MSG_CHECKING(
[whether make_request_fn() returns void])
ZFS_LINUX_TEST_RESULT([make_request_fn_void], [
AC_MSG_RESULT(yes)
AC_DEFINE(MAKE_REQUEST_FN_RET, void,
@ -99,3 +137,4 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
])
])
])
])

2
include/os/linux/kernel/linux/blkdev_compat.h
View File

@ -529,6 +529,8 @@ blk_generic_alloc_queue(make_request_fn make_request, int node_id)
{
#if defined(HAVE_BLK_ALLOC_QUEUE_REQUEST_FN)
return (blk_alloc_queue(make_request, node_id));
#elif defined(HAVE_BLK_ALLOC_QUEUE_REQUEST_FN_RH)
return (blk_alloc_queue_rh(make_request, node_id));
#else
struct request_queue *q = blk_alloc_queue(GFP_KERNEL);
if (q != NULL)