Linux compat: Minimum kernel version 3.10

Increase the minimum supported kernel version from 2.6.32 to 3.10.
This removes support for the following Linux enterprise distributions.

    Distribution     | Kernel | End of Life
    ---------------- | ------ | -------------
    Ubuntu 12.04 LTS | 3.2    | Apr 28, 2017
    SLES 11          | 3.0    | Mar 32, 2019
    RHEL / CentOS 6  | 2.6.32 | Nov 30, 2020

The following changes were made as part of removing support.

* Updated `configure` to enforce a minimum kernel version as
  specified in the META file (Linux-Minimum: 3.10).

    configure: error:
        *** Cannot build against kernel version 2.6.32.
        *** The minimum supported kernel version is 3.10.

* Removed all `configure` kABI checks and matching C code for
  interfaces which solely predate the Linux 3.10 kernel.

* Updated all `configure` kABI checks to fail when an interface is
  missing which was in the 3.10 kernel up to the latest 5.1 kernel.
  Removed the HAVE_* preprocessor defines for these checks and
  updated the code to unconditionally use the verified interface.

* Inverted the detection logic in several kABI checks to match
  the new interface as it appears in 3.10 and newer and not the
  legacy interface.

* Consolidated the following checks in to individual files. Due
  the large number of changes in the checks it made sense to handle
  this now.  It would be desirable to group other related checks in
  the same fashion, but this as left as future work.

  - config/kernel-blkdev.m4 - Block device kABI checks
  - config/kernel-blk-queue.m4 - Block queue kABI checks
  - config/kernel-bio.m4 - Bio interface kABI checks

* Removed the kABI checks for sops->nr_cached_objects() and
  sops->free_cached_objects().  These interfaces are currently unused.

Signed-off-by: Brian Behlendorf <[email protected]>
Closes #9566 

1 files changed, 363 insertions, 0 deletions

diff --git a/config/kernel-bio.m4 b/config/kernel-bio.m4
new file mode 100644
index 000000000..75a4a6de4
--- /dev/null
+++ b/config/kernel-bio.m4
@@ -0,0 +1,363 @@
+dnl #
+dnl # 2.6.36 API change,
+dnl # REQ_FAILFAST_{DEV|TRANSPORT|DRIVER}
+dnl # REQ_DISCARD
+dnl # REQ_FLUSH
+dnl #
+dnl # 4.8 - 4.9 API,
+dnl # REQ_FLUSH was renamed to REQ_PREFLUSH
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_REQ], [
+	ZFS_LINUX_TEST_SRC([req_failfast_mask], [
+		#include <linux/bio.h>
+	],[
+		int flags __attribute__ ((unused));
+		flags = REQ_FAILFAST_MASK;
+	])
+
+	ZFS_LINUX_TEST_SRC([req_discard], [
+		#include <linux/bio.h>
+	],[
+		int flags __attribute__ ((unused));
+		flags = REQ_DISCARD;
+	])
+
+	ZFS_LINUX_TEST_SRC([req_flush], [
+		#include <linux/bio.h>
+	],[
+		int flags __attribute__ ((unused));
+		flags = REQ_FLUSH;
+	])
+
+	ZFS_LINUX_TEST_SRC([req_preflush], [
+		#include <linux/bio.h>
+	],[
+		int flags __attribute__ ((unused));
+		flags = REQ_PREFLUSH;
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_FAILFAST_MASK], [
+	AC_MSG_CHECKING([whether REQ_FAILFAST_MASK is defined])
+	ZFS_LINUX_TEST_RESULT([req_failfast_mask], [
+		AC_MSG_RESULT(yes)
+	],[
+		ZFS_LINUX_TEST_ERROR([REQ_FAILFAST_MASK])
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_DISCARD], [
+	AC_MSG_CHECKING([whether REQ_DISCARD is defined])
+	ZFS_LINUX_TEST_RESULT([req_discard], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_DISCARD, 1, [REQ_DISCARD is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_FLUSH], [
+	AC_MSG_CHECKING([whether REQ_FLUSH is defined])
+	ZFS_LINUX_TEST_RESULT([req_flush], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_FLUSH, 1, [REQ_FLUSH is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_PREFLUSH], [
+	AC_MSG_CHECKING([whether REQ_PREFLUSH is defined])
+	ZFS_LINUX_TEST_RESULT([req_preflush], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_PREFLUSH, 1, [REQ_PREFLUSH is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # Linux 4.8 API,
+dnl #
+dnl # The bio_op() helper was introduced as a replacement for explicitly
+dnl # checking the bio->bi_rw flags.  The following checks are used to
+dnl # detect if a specific operation is supported.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_OPS], [
+	ZFS_LINUX_TEST_SRC([req_op_discard], [
+		#include <linux/blk_types.h>
+	],[
+		int op __attribute__ ((unused)) = REQ_OP_DISCARD;
+	])
+
+	ZFS_LINUX_TEST_SRC([req_op_secure_erase], [
+		#include <linux/blk_types.h>
+	],[
+		int op __attribute__ ((unused)) = REQ_OP_SECURE_ERASE;
+	])
+
+	ZFS_LINUX_TEST_SRC([req_op_flush], [
+		#include <linux/blk_types.h>
+	],[
+		int op __attribute__ ((unused)) = REQ_OP_FLUSH;
+	])
+
+	ZFS_LINUX_TEST_SRC([bio_bi_opf], [
+		#include <linux/bio.h>
+	],[
+		struct bio bio __attribute__ ((unused));
+		bio.bi_opf = 0;
+	])
+
+	ZFS_LINUX_TEST_SRC([bio_set_op_attrs], [
+		#include <linux/bio.h>
+	],[
+		struct bio *bio __attribute__ ((unused)) = NULL;
+		bio_set_op_attrs(bio, 0, 0);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_OP_DISCARD], [
+	AC_MSG_CHECKING([whether REQ_OP_DISCARD is defined])
+	ZFS_LINUX_TEST_RESULT([req_op_discard], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_OP_DISCARD, 1, [REQ_OP_DISCARD is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_OP_SECURE_ERASE], [
+	AC_MSG_CHECKING([whether REQ_OP_SECURE_ERASE is defined])
+	ZFS_LINUX_TEST_RESULT([req_op_secure_erase], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_OP_SECURE_ERASE, 1,
+		    [REQ_OP_SECURE_ERASE is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_REQ_OP_FLUSH], [
+	AC_MSG_CHECKING([whether REQ_OP_FLUSH is defined])
+	ZFS_LINUX_TEST_RESULT([req_op_flush], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_REQ_OP_FLUSH, 1, [REQ_OP_FLUSH is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_BI_OPF], [
+	AC_MSG_CHECKING([whether bio->bi_opf is defined])
+	ZFS_LINUX_TEST_RESULT([bio_bi_opf], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_BI_OPF, 1, [bio->bi_opf is defined])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_SET_OP_ATTRS], [
+	AC_MSG_CHECKING([whether bio_set_op_attrs is available])
+	ZFS_LINUX_TEST_RESULT([bio_set_op_attrs], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_SET_OP_ATTRS, 1,
+		    [bio_set_op_attrs is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # Linux 4.14 API,
+dnl #
+dnl # The bio_set_dev() helper macro was introduced as part of the transition
+dnl # to have struct gendisk in struct bio.
+dnl #
+dnl # Linux 5.0 API,
+dnl #
+dnl # The bio_set_dev() helper macro was updated to internally depend on
+dnl # bio_associate_blkg() symbol which is exported GPL-only.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_SET_DEV], [
+	ZFS_LINUX_TEST_SRC([bio_set_dev], [
+		#include <linux/bio.h>
+		#include <linux/fs.h>
+	],[
+		struct block_device *bdev = NULL;
+		struct bio *bio = NULL;
+		bio_set_dev(bio, bdev);
+	], [], [$ZFS_META_LICENSE])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_SET_DEV], [
+	AC_MSG_CHECKING([whether bio_set_dev() is available])
+	ZFS_LINUX_TEST_RESULT([bio_set_dev], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_SET_DEV, 1, [bio_set_dev() is available])
+
+		AC_MSG_CHECKING([whether bio_set_dev() is GPL-only])
+		ZFS_LINUX_TEST_RESULT([bio_set_dev_license], [
+			AC_MSG_RESULT(no)
+		],[
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_BIO_SET_DEV_GPL_ONLY, 1,
+			    [bio_set_dev() GPL-only])
+		])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # 4.3 API change
+dnl # Error argument dropped from bio_endio in favor of newly introduced
+dnl # bio->bi_error. This also replaces bio->bi_flags value BIO_UPTODATE.
+dnl # Introduced by torvalds/linux@4246a0b63bd8f56a1469b12eafeb875b1041a451
+dnl # ("block: add a bi_error field to struct bio").
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_END_IO_T_ARGS], [
+	ZFS_LINUX_TEST_SRC([bio_end_io_t_args], [
+		#include <linux/bio.h>
+		void wanted_end_io(struct bio *bio) { return; }
+		bio_end_io_t *end_io __attribute__ ((unused)) = wanted_end_io;
+	], [])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_END_IO_T_ARGS], [
+	AC_MSG_CHECKING([whether bio_end_io_t wants 1 arg])
+	ZFS_LINUX_TEST_RESULT([bio_end_io_t_args], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_1ARG_BIO_END_IO_T, 1,
+		    [bio_end_io_t wants 1 arg])
+	], [
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # 4.13 API change
+dnl # The bio->bi_error field was replaced with bio->bi_status which is an
+dnl # enum which describes all possible error types.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_BI_STATUS], [
+	ZFS_LINUX_TEST_SRC([bio_bi_status], [
+		#include <linux/bio.h>
+	], [
+		struct bio bio __attribute__ ((unused));
+		blk_status_t status __attribute__ ((unused)) = BLK_STS_OK;
+		bio.bi_status = status;
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_BI_STATUS], [
+	AC_MSG_CHECKING([whether bio->bi_status exists])
+	ZFS_LINUX_TEST_RESULT([bio_bi_status], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_BI_STATUS, 1, [bio->bi_status exists])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # 3.14 API change,
+dnl # Immutable biovecs. A number of fields of struct bio are moved to
+dnl # struct bvec_iter.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_BVEC_ITER], [
+	ZFS_LINUX_TEST_SRC([bio_bvec_iter], [
+		#include <linux/bio.h>
+	],[
+		struct bio bio;
+		bio.bi_iter.bi_sector = 0;
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_BVEC_ITER], [
+	AC_MSG_CHECKING([whether bio has bi_iter])
+	ZFS_LINUX_TEST_RESULT([bio_bvec_iter], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_BVEC_ITER, 1, [bio has bi_iter])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # 4.8 API change
+dnl # The rw argument has been removed from submit_bio/submit_bio_wait.
+dnl # Callers are now expected to set bio->bi_rw instead of passing it in.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_SUBMIT_BIO], [
+	ZFS_LINUX_TEST_SRC([submit_bio], [
+		#include <linux/bio.h>
+	],[
+		blk_qc_t blk_qc;
+		struct bio *bio = NULL;
+		blk_qc = submit_bio(bio);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_SUBMIT_BIO], [
+	AC_MSG_CHECKING([whether submit_bio() wants 1 arg])
+	ZFS_LINUX_TEST_RESULT([submit_bio], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_1ARG_SUBMIT_BIO, 1, [submit_bio() wants 1 arg])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # 2.6.34 API change
+dnl # current->bio_list
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_CURRENT_BIO_LIST], [
+	ZFS_LINUX_TEST_SRC([current_bio_list], [
+		#include <linux/sched.h>
+	], [
+		current->bio_list = (struct bio_list *) NULL;
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_CURRENT_BIO_LIST], [
+	AC_MSG_CHECKING([whether current->bio_list exists])
+	ZFS_LINUX_TEST_RESULT([current_bio_list], [
+		AC_MSG_RESULT(yes)
+	],[
+		ZFS_LINUX_TEST_ERROR([bio_list])
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO], [
+	ZFS_AC_KERNEL_SRC_REQ
+	ZFS_AC_KERNEL_SRC_BIO_OPS
+	ZFS_AC_KERNEL_SRC_BIO_SET_DEV
+	ZFS_AC_KERNEL_SRC_BIO_END_IO_T_ARGS
+	ZFS_AC_KERNEL_SRC_BIO_BI_STATUS
+	ZFS_AC_KERNEL_SRC_BIO_BVEC_ITER
+	ZFS_AC_KERNEL_SRC_BIO_SUBMIT_BIO
+	ZFS_AC_KERNEL_SRC_BIO_CURRENT_BIO_LIST
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO], [
+	ZFS_AC_KERNEL_BIO_REQ_FAILFAST_MASK
+	ZFS_AC_KERNEL_BIO_REQ_DISCARD
+	ZFS_AC_KERNEL_BIO_REQ_FLUSH
+	ZFS_AC_KERNEL_BIO_REQ_PREFLUSH
+
+	ZFS_AC_KERNEL_BIO_REQ_OP_DISCARD
+	ZFS_AC_KERNEL_BIO_REQ_OP_SECURE_ERASE
+	ZFS_AC_KERNEL_BIO_REQ_OP_FLUSH
+	ZFS_AC_KERNEL_BIO_BI_OPF
+	ZFS_AC_KERNEL_BIO_SET_OP_ATTRS
+
+	ZFS_AC_KERNEL_BIO_SET_DEV
+	ZFS_AC_KERNEL_BIO_END_IO_T_ARGS
+	ZFS_AC_KERNEL_BIO_BI_STATUS
+	ZFS_AC_KERNEL_BIO_BVEC_ITER
+	ZFS_AC_KERNEL_BIO_SUBMIT_BIO
+	ZFS_AC_KERNEL_BIO_CURRENT_BIO_LIST
+])