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 

12 files changed, 46 insertions, 490 deletions

diff --git a/module/os/linux/zfs/abd.c b/module/os/linux/zfs/abd.c
index ac6b0b742..40d73de0a 100644
--- a/module/os/linux/zfs/abd.c
+++ b/module/os/linux/zfs/abd.c
@@ -1043,20 +1043,6 @@ abd_release_ownership_of_buf(abd_t *abd)
 	ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
 }
 
-#ifndef HAVE_1ARG_KMAP_ATOMIC
-#define	NR_KM_TYPE (6)
-#ifdef _KERNEL
-int km_table[NR_KM_TYPE] = {
-	KM_USER0,
-	KM_USER1,
-	KM_BIO_SRC_IRQ,
-	KM_BIO_DST_IRQ,
-	KM_PTE0,
-	KM_PTE1,
-};
-#endif
-#endif
-
 struct abd_iter {
 	/* public interface */
 	void		*iter_mapaddr;	/* addr corresponding to iter_pos */
@@ -1068,9 +1054,6 @@ struct abd_iter {
 	size_t		iter_offset;	/* offset in current sg/abd_buf, */
 					/* abd_offset included */
 	struct scatterlist *iter_sg;	/* current sg */
-#ifndef HAVE_1ARG_KMAP_ATOMIC
-	int		iter_km;	/* KM_* for kmap_atomic */
-#endif
 };
 
 /*
@@ -1091,10 +1074,6 @@ abd_iter_init(struct abd_iter *aiter, abd_t *abd, int km_type)
 		aiter->iter_offset = ABD_SCATTER(abd).abd_offset;
 		aiter->iter_sg = ABD_SCATTER(abd).abd_sgl;
 	}
-#ifndef HAVE_1ARG_KMAP_ATOMIC
-	ASSERT3U(km_type, <, NR_KM_TYPE);
-	aiter->iter_km = km_type;
-#endif
 }
 
 /*
diff --git a/module/os/linux/zfs/policy.c b/module/os/linux/zfs/policy.c
index 7f9456a67..8cfc6fdc9 100644
--- a/module/os/linux/zfs/policy.c
+++ b/module/os/linux/zfs/policy.c
@@ -50,7 +50,7 @@ priv_policy_ns(const cred_t *cr, int capability, boolean_t all, int err,
 	if (cr != CRED() && (cr != kcred))
 		return (err);
 
-#if defined(CONFIG_USER_NS) && defined(HAVE_NS_CAPABLE)
+#if defined(CONFIG_USER_NS)
 	if (!(ns ? ns_capable(ns, capability) : capable(capability)))
 #else
 	if (!capable(capability))
@@ -73,10 +73,9 @@ priv_policy_user(const cred_t *cr, int capability, boolean_t all, int err)
 	 * All priv_policy_user checks are preceded by kuid/kgid_has_mapping()
 	 * checks. If we cannot do them, we shouldn't be using ns_capable()
 	 * since we don't know whether the affected files are valid in our
-	 * namespace. Note that kuid_has_mapping() came after cred->user_ns, so
-	 * we shouldn't need to re-check for HAVE_CRED_USER_NS
+	 * namespace.
 	 */
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	return (priv_policy_ns(cr, capability, all, err, cr->user_ns));
 #else
 	return (priv_policy_ns(cr, capability, all, err, NULL));
@@ -127,10 +126,10 @@ secpolicy_vnode_any_access(const cred_t *cr, struct inode *ip, uid_t owner)
 	if (crgetfsuid(cr) == owner)
 		return (0);
 
-	if (zpl_inode_owner_or_capable(ip))
+	if (inode_owner_or_capable(ip))
 		return (0);
 
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
 		return (EPERM);
 #endif
@@ -153,7 +152,7 @@ secpolicy_vnode_chown(const cred_t *cr, uid_t owner)
 	if (crgetfsuid(cr) == owner)
 		return (0);
 
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
 		return (EPERM);
 #endif
@@ -190,7 +189,7 @@ secpolicy_vnode_setdac(const cred_t *cr, uid_t owner)
 	if (crgetfsuid(cr) == owner)
 		return (0);
 
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
 		return (EPERM);
 #endif
@@ -218,7 +217,7 @@ secpolicy_vnode_setid_retain(const cred_t *cr, boolean_t issuidroot)
 int
 secpolicy_vnode_setids_setgids(const cred_t *cr, gid_t gid)
 {
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	if (!kgid_has_mapping(cr->user_ns, SGID_TO_KGID(gid)))
 		return (EPERM);
 #endif
@@ -269,7 +268,7 @@ secpolicy_vnode_setid_modify(const cred_t *cr, uid_t owner)
 	if (crgetfsuid(cr) == owner)
 		return (0);
 
-#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
+#if defined(CONFIG_USER_NS)
 	if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
 		return (EPERM);
 #endif
diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
index 6b4c035f0..ed0e7a173 100644
--- a/module/os/linux/zfs/vdev_disk.c
+++ b/module/os/linux/zfs/vdev_disk.c
@@ -54,8 +54,6 @@ typedef struct dio_request {
 	struct bio		*dr_bio[0];	/* Attached bio's */
 } dio_request_t;
 
-
-#if defined(HAVE_OPEN_BDEV_EXCLUSIVE) || defined(HAVE_BLKDEV_GET_BY_PATH)
 static fmode_t
 vdev_bdev_mode(int smode)
 {
@@ -71,20 +69,6 @@ vdev_bdev_mode(int smode)
 
 	return (mode);
 }
-#else
-static int
-vdev_bdev_mode(int smode)
-{
-	int mode = 0;
-
-	ASSERT3S(smode & (FREAD | FWRITE), !=, 0);
-
-	if ((smode & FREAD) && !(smode & FWRITE))
-		mode = SB_RDONLY;
-
-	return (mode);
-}
-#endif /* HAVE_OPEN_BDEV_EXCLUSIVE */
 
 /*
  * Returns the usable capacity (in bytes) for the partition or disk.
@@ -267,14 +251,15 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 				reread_part = B_TRUE;
 			}
 
-			vdev_bdev_close(bdev, mode);
+			blkdev_put(bdev, mode | FMODE_EXCL);
 		}
 
 		if (reread_part) {
-			bdev = vdev_bdev_open(disk_name, mode, zfs_vdev_holder);
+			bdev = blkdev_get_by_path(disk_name, mode | FMODE_EXCL,
+			    zfs_vdev_holder);
 			if (!IS_ERR(bdev)) {
 				int error = vdev_bdev_reread_part(bdev);
-				vdev_bdev_close(bdev, mode);
+				blkdev_put(bdev, mode | FMODE_EXCL);
 				if (error == 0)
 					bdev_retry_count = 100;
 			}
@@ -311,7 +296,8 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 	 */
 	bdev = ERR_PTR(-ENXIO);
 	while (IS_ERR(bdev) && count < bdev_retry_count) {
-		bdev = vdev_bdev_open(v->vdev_path, mode, zfs_vdev_holder);
+		bdev = blkdev_get_by_path(v->vdev_path, mode | FMODE_EXCL,
+		    zfs_vdev_holder);
 		if (unlikely(PTR_ERR(bdev) == -ENOENT)) {
 			schedule_timeout(MSEC_TO_TICK(10));
 			count++;
@@ -336,7 +322,7 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 	struct request_queue *q = bdev_get_queue(vd->vd_bdev);
 
 	/*  Determine the physical block size */
-	block_size = vdev_bdev_block_size(vd->vd_bdev);
+	block_size = bdev_physical_block_size(vd->vd_bdev);
 
 	/* Clear the nowritecache bit, causes vdev_reopen() to try again. */
 	v->vdev_nowritecache = B_FALSE;
@@ -374,8 +360,8 @@ vdev_disk_close(vdev_t *v)
 		return;
 
 	if (vd->vd_bdev != NULL) {
-		vdev_bdev_close(vd->vd_bdev,
-		    vdev_bdev_mode(spa_mode(v->vdev_spa)));
+		blkdev_put(vd->vd_bdev,
+		    vdev_bdev_mode(spa_mode(v->vdev_spa)) | FMODE_EXCL);
 	}
 
 	rw_destroy(&vd->vd_lock);
@@ -563,17 +549,10 @@ bio_set_dev(struct bio *bio, struct block_device *bdev)
 static inline void
 vdev_submit_bio(struct bio *bio)
 {
-#ifdef HAVE_CURRENT_BIO_TAIL
-	struct bio **bio_tail = current->bio_tail;
-	current->bio_tail = NULL;
-	vdev_submit_bio_impl(bio);
-	current->bio_tail = bio_tail;
-#else
 	struct bio_list *bio_list = current->bio_list;
 	current->bio_list = NULL;
 	vdev_submit_bio_impl(bio);
 	current->bio_list = bio_list;
-#endif
 }
 
 static int
@@ -585,9 +564,8 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio,
 	uint64_t bio_offset;
 	int bio_size, bio_count = 16;
 	int i = 0, error = 0;
-#if defined(HAVE_BLK_QUEUE_HAVE_BLK_PLUG)
 	struct blk_plug plug;
-#endif
+
 	/*
 	 * Accessing outside the block device is never allowed.
 	 */
@@ -666,20 +644,16 @@ retry:
 	/* Extra reference to protect dio_request during vdev_submit_bio */
 	vdev_disk_dio_get(dr);
 
-#if defined(HAVE_BLK_QUEUE_HAVE_BLK_PLUG)
 	if (dr->dr_bio_count > 1)
 		blk_start_plug(&plug);
-#endif
 
 	/* Submit all bio's associated with this dio */
 	for (i = 0; i < dr->dr_bio_count; i++)
 		if (dr->dr_bio[i])
 			vdev_submit_bio(dr->dr_bio[i]);
 
-#if defined(HAVE_BLK_QUEUE_HAVE_BLK_PLUG)
 	if (dr->dr_bio_count > 1)
 		blk_finish_plug(&plug);
-#endif
 
 	(void) vdev_disk_dio_put(dr);
 
@@ -736,7 +710,7 @@ vdev_disk_io_start(zio_t *zio)
 	vdev_t *v = zio->io_vd;
 	vdev_disk_t *vd = v->vdev_tsd;
 	unsigned long trim_flags = 0;
-	int rw, flags, error;
+	int rw, error;
 
 	/*
 	 * If the vdev is closed, it's likely in the REMOVED or FAULTED state.
@@ -801,24 +775,10 @@ vdev_disk_io_start(zio_t *zio)
 		return;
 	case ZIO_TYPE_WRITE:
 		rw = WRITE;
-#if defined(HAVE_BLK_QUEUE_HAVE_BIO_RW_UNPLUG)
-		flags = (1 << BIO_RW_UNPLUG);
-#elif defined(REQ_UNPLUG)
-		flags = REQ_UNPLUG;
-#else
-		flags = 0;
-#endif
 		break;
 
 	case ZIO_TYPE_READ:
 		rw = READ;
-#if defined(HAVE_BLK_QUEUE_HAVE_BIO_RW_UNPLUG)
-		flags = (1 << BIO_RW_UNPLUG);
-#elif defined(REQ_UNPLUG)
-		flags = REQ_UNPLUG;
-#else
-		flags = 0;
-#endif
 		break;
 
 	case ZIO_TYPE_TRIM:
@@ -843,7 +803,7 @@ vdev_disk_io_start(zio_t *zio)
 
 	zio->io_target_timestamp = zio_handle_io_delay(zio);
 	error = __vdev_disk_physio(vd->vd_bdev, zio,
-	    zio->io_size, zio->io_offset, rw, flags);
+	    zio->io_size, zio->io_offset, rw, 0);
 	rw_exit(&vd->vd_lock);
 
 	if (error) {
@@ -866,7 +826,7 @@ vdev_disk_io_done(zio_t *zio)
 		vdev_disk_t *vd = v->vdev_tsd;
 
 		if (check_disk_change(vd->vd_bdev)) {
-			vdev_bdev_invalidate(vd->vd_bdev);
+			invalidate_bdev(vd->vd_bdev);
 			v->vdev_remove_wanted = B_TRUE;
 			spa_async_request(zio->io_spa, SPA_ASYNC_REMOVE);
 		}
diff --git a/module/os/linux/zfs/zfs_ctldir.c b/module/os/linux/zfs/zfs_ctldir.c
index 3a53c75b1..909748f51 100644
--- a/module/os/linux/zfs/zfs_ctldir.c
+++ b/module/os/linux/zfs/zfs_ctldir.c
@@ -1106,7 +1106,7 @@ zfsctl_snapshot_mount(struct path *path, int flags)
 	 */
 	spath = *path;
 	path_get(&spath);
-	if (zpl_follow_down_one(&spath)) {
+	if (follow_down_one(&spath)) {
 		snap_zfsvfs = ITOZSB(spath.dentry->d_inode);
 		snap_zfsvfs->z_parent = zfsvfs;
 		dentry = spath.dentry;
diff --git a/module/os/linux/zfs/zfs_vfsops.c b/module/os/linux/zfs/zfs_vfsops.c
index 75840dfe7..c0acaab0b 100644
--- a/module/os/linux/zfs/zfs_vfsops.c
+++ b/module/os/linux/zfs/zfs_vfsops.c
@@ -1608,7 +1608,6 @@ zfs_root(zfsvfs_t *zfsvfs, struct inode **ipp)
 	return (error);
 }
 
-#ifdef HAVE_D_PRUNE_ALIASES
 /*
  * Linux kernels older than 3.1 do not support a per-filesystem shrinker.
  * To accommodate this we must improvise and manually walk the list of znodes
@@ -1666,7 +1665,6 @@ zfs_prune_aliases(zfsvfs_t *zfsvfs, unsigned long nr_to_scan)
 
 	return (objects);
 }
-#endif /* HAVE_D_PRUNE_ALIASES */
 
 /*
  * The ARC has requested that the filesystem drop entries from the dentry
@@ -1678,13 +1676,11 @@ zfs_prune(struct super_block *sb, unsigned long nr_to_scan, int *objects)
 {
 	zfsvfs_t *zfsvfs = sb->s_fs_info;
 	int error = 0;
-#if defined(HAVE_SHRINK) || defined(HAVE_SPLIT_SHRINKER_CALLBACK)
 	struct shrinker *shrinker = &sb->s_shrink;
 	struct shrink_control sc = {
 		.nr_to_scan = nr_to_scan,
 		.gfp_mask = GFP_KERNEL,
 	};
-#endif
 
 	ZFS_ENTER(zfsvfs);
 
@@ -1702,7 +1698,7 @@ zfs_prune(struct super_block *sb, unsigned long nr_to_scan, int *objects)
 
 #elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
 	*objects = (*shrinker->scan_objects)(shrinker, &sc);
-#elif defined(HAVE_SHRINK)
+#elif defined(HAVE_SINGLE_SHRINKER_CALLBACK)
 	*objects = (*shrinker->shrink)(shrinker, &sc);
 #elif defined(HAVE_D_PRUNE_ALIASES)
 #define	D_PRUNE_ALIASES_IS_DEFAULT
@@ -1877,8 +1873,7 @@ zfsvfs_teardown(zfsvfs_t *zfsvfs, boolean_t unmounting)
 	return (0);
 }
 
-#if !defined(HAVE_2ARGS_BDI_SETUP_AND_REGISTER) && \
-	!defined(HAVE_3ARGS_BDI_SETUP_AND_REGISTER)
+#if defined(HAVE_SUPER_SETUP_BDI_NAME)
 atomic_long_t zfs_bdi_seq = ATOMIC_LONG_INIT(0);
 #endif
 
diff --git a/module/os/linux/zfs/zpl_ctldir.c b/module/os/linux/zfs/zpl_ctldir.c
index 6df367b81..052d937de 100644
--- a/module/os/linux/zfs/zpl_ctldir.c
+++ b/module/os/linux/zfs/zpl_ctldir.c
@@ -114,11 +114,7 @@ zpl_root_getattr_impl(const struct path *path, struct kstat *stat,
 ZPL_GETATTR_WRAPPER(zpl_root_getattr);
 
 static struct dentry *
-#ifdef HAVE_LOOKUP_NAMEIDATA
-zpl_root_lookup(struct inode *dip, struct dentry *dentry, struct nameidata *nd)
-#else
 zpl_root_lookup(struct inode *dip, struct dentry *dentry, unsigned int flags)
-#endif
 {
 	cred_t *cr = CRED();
 	struct inode *ip;
@@ -160,7 +156,6 @@ const struct inode_operations zpl_ops_root = {
 	.getattr	= zpl_root_getattr,
 };
 
-#ifdef HAVE_AUTOMOUNT
 static struct vfsmount *
 zpl_snapdir_automount(struct path *path)
 {
@@ -179,7 +174,6 @@ zpl_snapdir_automount(struct path *path)
 	 */
 	return (NULL);
 }
-#endif /* HAVE_AUTOMOUNT */
 
 /*
  * Negative dentries must always be revalidated so newly created snapshots
@@ -206,21 +200,13 @@ dentry_operations_t zpl_dops_snapdirs = {
  * name space.  While it might be possible to add compatibility
  * code to accomplish this it would require considerable care.
  */
-#ifdef HAVE_AUTOMOUNT
 	.d_automount	= zpl_snapdir_automount,
-#endif /* HAVE_AUTOMOUNT */
 	.d_revalidate	= zpl_snapdir_revalidate,
 };
 
 static struct dentry *
-#ifdef HAVE_LOOKUP_NAMEIDATA
-zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
-    struct nameidata *nd)
-#else
 zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
     unsigned int flags)
-#endif
-
 {
 	fstrans_cookie_t cookie;
 	cred_t *cr = CRED();
@@ -241,9 +227,7 @@ zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
 	ASSERT(error == 0 || ip == NULL);
 	d_clear_d_op(dentry);
 	d_set_d_op(dentry, &zpl_dops_snapdirs);
-#ifdef HAVE_AUTOMOUNT
 	dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
-#endif
 
 	return (d_splice_alias(ip, dentry));
 }
@@ -348,7 +332,7 @@ zpl_snapdir_rmdir(struct inode *dip, struct dentry *dentry)
 }
 
 static int
-zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, zpl_umode_t mode)
+zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
 {
 	cred_t *cr = CRED();
 	vattr_t *vap;
@@ -433,13 +417,8 @@ const struct inode_operations zpl_ops_snapdir = {
 };
 
 static struct dentry *
-#ifdef HAVE_LOOKUP_NAMEIDATA
-zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
-    struct nameidata *nd)
-#else
 zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
     unsigned int flags)
-#endif
 {
 	fstrans_cookie_t cookie;
 	cred_t *cr = CRED();
diff --git a/module/os/linux/zfs/zpl_export.c b/module/os/linux/zfs/zpl_export.c
index a264d664c..97e9283dd 100644
--- a/module/os/linux/zfs/zpl_export.c
+++ b/module/os/linux/zfs/zpl_export.c
@@ -65,25 +65,6 @@ zpl_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len, int connectable)
 }
 
 static struct dentry *
-zpl_dentry_obtain_alias(struct inode *ip)
-{
-	struct dentry *result;
-
-#ifdef HAVE_D_OBTAIN_ALIAS
-	result = d_obtain_alias(ip);
-#else
-	result = d_alloc_anon(ip);
-
-	if (result == NULL) {
-		iput(ip);
-		result = ERR_PTR(-ENOMEM);
-	}
-#endif /* HAVE_D_OBTAIN_ALIAS */
-
-	return (result);
-}
-
-static struct dentry *
 zpl_fh_to_dentry(struct super_block *sb, struct fid *fh,
     int fh_len, int fh_type)
 {
@@ -121,7 +102,7 @@ zpl_fh_to_dentry(struct super_block *sb, struct fid *fh,
 
 	ASSERT((ip != NULL) && !IS_ERR(ip));
 
-	return (zpl_dentry_obtain_alias(ip));
+	return (d_obtain_alias(ip));
 }
 
 static struct dentry *
@@ -142,10 +123,9 @@ zpl_get_parent(struct dentry *child)
 	if (error)
 		return (ERR_PTR(error));
 
-	return (zpl_dentry_obtain_alias(ip));
+	return (d_obtain_alias(ip));
 }
 
-#ifdef HAVE_COMMIT_METADATA
 static int
 zpl_commit_metadata(struct inode *inode)
 {
@@ -165,13 +145,10 @@ zpl_commit_metadata(struct inode *inode)
 
 	return (error);
 }
-#endif /* HAVE_COMMIT_METADATA */
 
 const struct export_operations zpl_export_operations = {
 	.encode_fh		= zpl_encode_fh,
 	.fh_to_dentry		= zpl_fh_to_dentry,
 	.get_parent		= zpl_get_parent,
-#ifdef HAVE_COMMIT_METADATA
 	.commit_metadata	= zpl_commit_metadata,
-#endif /* HAVE_COMMIT_METADATA */
 };
diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
index acad4670d..b098703c2 100644
--- a/module/os/linux/zfs/zpl_file.c
+++ b/module/os/linux/zfs/zpl_file.c
@@ -108,40 +108,7 @@ zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
 }
 #endif /* !HAVE_VFS_ITERATE && !HAVE_VFS_ITERATE_SHARED */
 
-#if defined(HAVE_FSYNC_WITH_DENTRY)
-/*
- * Linux 2.6.x - 2.6.34 API,
- * Through 2.6.34 the nfsd kernel server would pass a NULL 'file struct *'
- * to the fops->fsync() hook.  For this reason, we must be careful not to
- * use filp unconditionally.
- */
-static int
-zpl_fsync(struct file *filp, struct dentry *dentry, int datasync)
-{
-	cred_t *cr = CRED();
-	int error;
-	fstrans_cookie_t cookie;
-
-	crhold(cr);
-	cookie = spl_fstrans_mark();
-	error = -zfs_fsync(dentry->d_inode, datasync, cr);
-	spl_fstrans_unmark(cookie);
-	crfree(cr);
-	ASSERT3S(error, <=, 0);
-
-	return (error);
-}
-
-#ifdef HAVE_FILE_AIO_FSYNC
-static int
-zpl_aio_fsync(struct kiocb *kiocb, int datasync)
-{
-	struct file *filp = kiocb->ki_filp;
-	return (zpl_fsync(filp, file_dentry(filp), datasync));
-}
-#endif
-
-#elif defined(HAVE_FSYNC_WITHOUT_DENTRY)
+#if defined(HAVE_FSYNC_WITHOUT_DENTRY)
 /*
  * Linux 2.6.35 - 3.0 API,
  * As of 2.6.35 the dentry argument to the fops->fsync() hook was deemed
@@ -758,8 +725,7 @@ zpl_writepage(struct page *pp, struct writeback_control *wbc)
  * is FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE.  The FALLOC_FL_PUNCH_HOLE
  * flag was introduced in the 2.6.38 kernel.
  */
-#if defined(HAVE_FILE_FALLOCATE) || defined(HAVE_INODE_FALLOCATE)
-long
+static long
 zpl_fallocate_common(struct inode *ip, int mode, loff_t offset, loff_t len)
 {
 	int error = -EOPNOTSUPP;
@@ -803,16 +769,13 @@ zpl_fallocate_common(struct inode *ip, int mode, loff_t offset, loff_t len)
 	ASSERT3S(error, <=, 0);
 	return (error);
 }
-#endif /* defined(HAVE_FILE_FALLOCATE) || defined(HAVE_INODE_FALLOCATE) */
 
-#ifdef HAVE_FILE_FALLOCATE
 static long
 zpl_fallocate(struct file *filp, int mode, loff_t offset, loff_t len)
 {
 	return zpl_fallocate_common(file_inode(filp),
 	    mode, offset, len);
 }
-#endif /* HAVE_FILE_FALLOCATE */
 
 #define	ZFS_FL_USER_VISIBLE	(FS_FL_USER_VISIBLE | ZFS_PROJINHERIT_FL)
 #define	ZFS_FL_USER_MODIFIABLE	(FS_FL_USER_MODIFIABLE | ZFS_PROJINHERIT_FL)
@@ -883,7 +846,7 @@ __zpl_ioctl_setflags(struct inode *ip, uint32_t ioctl_flags, xvattr_t *xva)
 	    !capable(CAP_LINUX_IMMUTABLE))
 		return (-EACCES);
 
-	if (!zpl_inode_owner_or_capable(ip))
+	if (!inode_owner_or_capable(ip))
 		return (-EACCES);
 
 	xva_init(xva);
@@ -1048,9 +1011,7 @@ const struct file_operations zpl_file_operations = {
 #ifdef HAVE_FILE_AIO_FSYNC
 	.aio_fsync	= zpl_aio_fsync,
 #endif
-#ifdef HAVE_FILE_FALLOCATE
 	.fallocate	= zpl_fallocate,
-#endif /* HAVE_FILE_FALLOCATE */
 	.unlocked_ioctl	= zpl_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= zpl_compat_ioctl,
diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
index 4c628f608..7912a5b3d 100644
--- a/module/os/linux/zfs/zpl_inode.c
+++ b/module/os/linux/zfs/zpl_inode.c
@@ -35,11 +35,7 @@
 
 
 static struct dentry *
-#ifdef HAVE_LOOKUP_NAMEIDATA
-zpl_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
-#else
 zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
-#endif
 {
 	cred_t *cr = CRED();
 	struct inode *ip;
@@ -113,7 +109,7 @@ zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 }
 
 void
-zpl_vap_init(vattr_t *vap, struct inode *dir, zpl_umode_t mode, cred_t *cr)
+zpl_vap_init(vattr_t *vap, struct inode *dir, umode_t mode, cred_t *cr)
 {
 	vap->va_mask = ATTR_MODE;
 	vap->va_mode = mode;
@@ -129,13 +125,7 @@ zpl_vap_init(vattr_t *vap, struct inode *dir, zpl_umode_t mode, cred_t *cr)
 }
 
 static int
-#ifdef HAVE_CREATE_NAMEIDATA
-zpl_create(struct inode *dir, struct dentry *dentry, zpl_umode_t mode,
-    struct nameidata *nd)
-#else
-zpl_create(struct inode *dir, struct dentry *dentry, zpl_umode_t mode,
-    bool flag)
-#endif
+zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
 {
 	cred_t *cr = CRED();
 	struct inode *ip;
@@ -169,7 +159,7 @@ zpl_create(struct inode *dir, struct dentry *dentry, zpl_umode_t mode,
 }
 
 static int
-zpl_mknod(struct inode *dir, struct dentry *dentry, zpl_umode_t mode,
+zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
     dev_t rdev)
 {
 	cred_t *cr = CRED();
@@ -213,7 +203,7 @@ zpl_mknod(struct inode *dir, struct dentry *dentry, zpl_umode_t mode,
 
 #ifdef HAVE_TMPFILE
 static int
-zpl_tmpfile(struct inode *dir, struct dentry *dentry, zpl_umode_t mode)
+zpl_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	cred_t *cr = CRED();
 	struct inode *ip;
@@ -277,7 +267,7 @@ zpl_unlink(struct inode *dir, struct dentry *dentry)
 }
 
 static int
-zpl_mkdir(struct inode *dir, struct dentry *dentry, zpl_umode_t mode)
+zpl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	cred_t *cr = CRED();
 	vattr_t *vap;
@@ -612,46 +602,6 @@ out:
 	return (error);
 }
 
-#ifdef HAVE_INODE_TRUNCATE_RANGE
-static void
-zpl_truncate_range(struct inode *ip, loff_t start, loff_t end)
-{
-	cred_t *cr = CRED();
-	flock64_t bf;
-	fstrans_cookie_t cookie;
-
-	ASSERT3S(start, <=, end);
-
-	/*
-	 * zfs_freesp() will interpret (len == 0) as meaning "truncate until
-	 * the end of the file". We don't want that.
-	 */
-	if (start == end)
-		return;
-
-	crhold(cr);
-
-	bf.l_type = F_WRLCK;
-	bf.l_whence = SEEK_SET;
-	bf.l_start = start;
-	bf.l_len = end - start;
-	bf.l_pid = 0;
-	cookie = spl_fstrans_mark();
-	zfs_space(ip, F_FREESP, &bf, FWRITE, start, cr);
-	spl_fstrans_unmark(cookie);
-
-	crfree(cr);
-}
-#endif /* HAVE_INODE_TRUNCATE_RANGE */
-
-#ifdef HAVE_INODE_FALLOCATE
-static long
-zpl_fallocate(struct inode *ip, int mode, loff_t offset, loff_t len)
-{
-	return (zpl_fallocate_common(ip, mode, offset, len));
-}
-#endif /* HAVE_INODE_FALLOCATE */
-
 const struct inode_operations zpl_inode_operations = {
 	.setattr	= zpl_setattr,
 	.getattr	= zpl_getattr,
@@ -661,23 +611,11 @@ const struct inode_operations zpl_inode_operations = {
 	.removexattr	= generic_removexattr,
 #endif
 	.listxattr	= zpl_xattr_list,
-#ifdef HAVE_INODE_TRUNCATE_RANGE
-	.truncate_range = zpl_truncate_range,
-#endif /* HAVE_INODE_TRUNCATE_RANGE */
-#ifdef HAVE_INODE_FALLOCATE
-	.fallocate	= zpl_fallocate,
-#endif /* HAVE_INODE_FALLOCATE */
 #if defined(CONFIG_FS_POSIX_ACL)
 #if defined(HAVE_SET_ACL)
 	.set_acl	= zpl_set_acl,
-#endif
-#if defined(HAVE_GET_ACL)
+#endif /* HAVE_SET_ACL */
 	.get_acl	= zpl_get_acl,
-#elif defined(HAVE_CHECK_ACL)
-	.check_acl	= zpl_check_acl,
-#elif defined(HAVE_PERMISSION)
-	.permission	= zpl_permission,
-#endif /* HAVE_GET_ACL | HAVE_CHECK_ACL | HAVE_PERMISSION */
 #endif /* CONFIG_FS_POSIX_ACL */
 };
 
@@ -709,14 +647,8 @@ const struct inode_operations zpl_dir_inode_operations = {
 #if defined(CONFIG_FS_POSIX_ACL)
 #if defined(HAVE_SET_ACL)
 	.set_acl	= zpl_set_acl,
-#endif
-#if defined(HAVE_GET_ACL)
+#endif /* HAVE_SET_ACL */
 	.get_acl	= zpl_get_acl,
-#elif defined(HAVE_CHECK_ACL)
-	.check_acl	= zpl_check_acl,
-#elif defined(HAVE_PERMISSION)
-	.permission	= zpl_permission,
-#endif /* HAVE_GET_ACL | HAVE_CHECK_ACL | HAVE_PERMISSION */
 #endif /* CONFIG_FS_POSIX_ACL */
 };
 
@@ -754,13 +686,7 @@ const struct inode_operations zpl_special_inode_operations = {
 #if defined(CONFIG_FS_POSIX_ACL)
 #if defined(HAVE_SET_ACL)
 	.set_acl	= zpl_set_acl,
-#endif
-#if defined(HAVE_GET_ACL)
+#endif /* HAVE_SET_ACL */
 	.get_acl	= zpl_get_acl,
-#elif defined(HAVE_CHECK_ACL)
-	.check_acl	= zpl_check_acl,
-#elif defined(HAVE_PERMISSION)
-	.permission	= zpl_permission,
-#endif /* HAVE_GET_ACL | HAVE_CHECK_ACL | HAVE_PERMISSION */
 #endif /* CONFIG_FS_POSIX_ACL */
 };
diff --git a/module/os/linux/zfs/zpl_super.c b/module/os/linux/zfs/zpl_super.c
index 810ab2898..eafd4952b 100644
--- a/module/os/linux/zfs/zpl_super.c
+++ b/module/os/linux/zfs/zpl_super.c
@@ -81,18 +81,6 @@ zpl_dirty_inode(struct inode *ip)
  * unhashed and has no links the default policy is to evict it
  * immediately.
  *
- * Prior to 2.6.36 this eviction was accomplished by the vfs calling
- * ->delete_inode().  It was ->delete_inode()'s responsibility to
- * truncate the inode pages and call clear_inode().  The call to
- * clear_inode() synchronously invalidates all the buffers and
- * calls ->clear_inode().  It was ->clear_inode()'s responsibility
- * to cleanup and filesystem specific data before freeing the inode.
- *
- * This elaborate mechanism was replaced by ->evict_inode() which
- * does the job of both ->delete_inode() and ->clear_inode().  It
- * will be called exactly once, and when it returns the inode must
- * be in a state where it can simply be freed.i
- *
  * The ->evict_inode() callback must minimally truncate the inode pages,
  * and call clear_inode().  For 2.6.35 and later kernels this will
  * simply update the inode state, with the sync occurring before the
@@ -102,7 +90,6 @@ zpl_dirty_inode(struct inode *ip)
  * any remaining inode specific data via zfs_inactive().
  * remaining filesystem specific data.
  */
-#ifdef HAVE_EVICT_INODE
 static void
 zpl_evict_inode(struct inode *ip)
 {
@@ -115,32 +102,6 @@ zpl_evict_inode(struct inode *ip)
 	spl_fstrans_unmark(cookie);
 }
 
-#else
-
-static void
-zpl_drop_inode(struct inode *ip)
-{
-	generic_delete_inode(ip);
-}
-
-static void
-zpl_clear_inode(struct inode *ip)
-{
-	fstrans_cookie_t cookie;
-
-	cookie = spl_fstrans_mark();
-	zfs_inactive(ip);
-	spl_fstrans_unmark(cookie);
-}
-
-static void
-zpl_inode_delete(struct inode *ip)
-{
-	truncate_setsize(ip, 0);
-	clear_inode(ip);
-}
-#endif /* HAVE_EVICT_INODE */
-
 static void
 zpl_put_super(struct super_block *sb)
 {
@@ -241,19 +202,11 @@ __zpl_show_options(struct seq_file *seq, zfsvfs_t *zfsvfs)
 	return (0);
 }
 
-#ifdef HAVE_SHOW_OPTIONS_WITH_DENTRY
 static int
 zpl_show_options(struct seq_file *seq, struct dentry *root)
 {
 	return (__zpl_show_options(seq, root->d_sb->s_fs_info));
 }
-#else
-static int
-zpl_show_options(struct seq_file *seq, struct vfsmount *vfsp)
-{
-	return (__zpl_show_options(seq, vfsp->mnt_sb->s_fs_info));
-}
-#endif /* HAVE_SHOW_OPTIONS_WITH_DENTRY */
 
 static int
 zpl_fill_super(struct super_block *sb, void *data, int silent)
@@ -301,7 +254,7 @@ zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 	 * this can prevent the pool sync and cause a deadlock.
 	 */
 	dsl_pool_rele(dmu_objset_pool(os), FTAG);
-	s = zpl_sget(fs_type, zpl_test_super, set_anon_super, flags, os);
+	s = sget(fs_type, zpl_test_super, set_anon_super, flags, os);
 	dsl_dataset_rele(dmu_objset_ds(os), FTAG);
 
 	if (IS_ERR(s))
@@ -322,7 +275,6 @@ zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 	return (s);
 }
 
-#ifdef HAVE_FST_MOUNT
 static struct dentry *
 zpl_mount(struct file_system_type *fs_type, int flags,
     const char *osname, void *data)
@@ -335,32 +287,12 @@ zpl_mount(struct file_system_type *fs_type, int flags,
 
 	return (dget(sb->s_root));
 }
-#else
-static int
-zpl_get_sb(struct file_system_type *fs_type, int flags,
-    const char *osname, void *data, struct vfsmount *mnt)
-{
-	zfs_mnt_t zm = { .mnt_osname = osname, .mnt_data = data };
-
-	struct super_block *sb = zpl_mount_impl(fs_type, flags, &zm);
-	if (IS_ERR(sb))
-		return (PTR_ERR(sb));
-
-	(void) simple_set_mnt(mnt, sb);
-
-	return (0);
-}
-#endif /* HAVE_FST_MOUNT */
 
 static void
 zpl_kill_sb(struct super_block *sb)
 {
 	zfs_preumount(sb);
 	kill_anon_super(sb);
-
-#ifdef HAVE_S_INSTANCES_LIST_HEAD
-	sb->s_instances.next = &(zpl_fs_type.fs_supers);
-#endif /* HAVE_S_INSTANCES_LIST_HEAD */
 }
 
 void
@@ -372,55 +304,23 @@ zpl_prune_sb(int64_t nr_to_scan, void *arg)
 	(void) -zfs_prune(sb, nr_to_scan, &objects);
 }
 
-#ifdef HAVE_NR_CACHED_OBJECTS
-static int
-zpl_nr_cached_objects(struct super_block *sb)
-{
-	return (0);
-}
-#endif /* HAVE_NR_CACHED_OBJECTS */
-
-#ifdef HAVE_FREE_CACHED_OBJECTS
-static void
-zpl_free_cached_objects(struct super_block *sb, int nr_to_scan)
-{
-	/* noop */
-}
-#endif /* HAVE_FREE_CACHED_OBJECTS */
-
 const struct super_operations zpl_super_operations = {
 	.alloc_inode		= zpl_inode_alloc,
 	.destroy_inode		= zpl_inode_destroy,
 	.dirty_inode		= zpl_dirty_inode,
 	.write_inode		= NULL,
-#ifdef HAVE_EVICT_INODE
 	.evict_inode		= zpl_evict_inode,
-#else
-	.drop_inode		= zpl_drop_inode,
-	.clear_inode		= zpl_clear_inode,
-	.delete_inode		= zpl_inode_delete,
-#endif /* HAVE_EVICT_INODE */
 	.put_super		= zpl_put_super,
 	.sync_fs		= zpl_sync_fs,
 	.statfs			= zpl_statfs,
 	.remount_fs		= zpl_remount_fs,
 	.show_options		= zpl_show_options,
 	.show_stats		= NULL,
-#ifdef HAVE_NR_CACHED_OBJECTS
-	.nr_cached_objects	= zpl_nr_cached_objects,
-#endif /* HAVE_NR_CACHED_OBJECTS */
-#ifdef HAVE_FREE_CACHED_OBJECTS
-	.free_cached_objects	= zpl_free_cached_objects,
-#endif /* HAVE_FREE_CACHED_OBJECTS */
 };
 
 struct file_system_type zpl_fs_type = {
 	.owner			= THIS_MODULE,
 	.name			= ZFS_DRIVER,
-#ifdef HAVE_FST_MOUNT
 	.mount			= zpl_mount,
-#else
-	.get_sb			= zpl_get_sb,
-#endif /* HAVE_FST_MOUNT */
 	.kill_sb		= zpl_kill_sb,
 };
diff --git a/module/os/linux/zfs/zpl_xattr.c b/module/os/linux/zfs/zpl_xattr.c
index 082287b00..fdcd77541 100644
--- a/module/os/linux/zfs/zpl_xattr.c
+++ b/module/os/linux/zfs/zpl_xattr.c
@@ -113,9 +113,6 @@ zpl_xattr_permission(xattr_filldir_t *xf, const char *name, int name_len)
 #elif defined(HAVE_XATTR_LIST_HANDLER)
 		if (!handler->list(handler, d, NULL, 0, name, name_len))
 			return (0);
-#elif defined(HAVE_XATTR_LIST_INODE)
-		if (!handler->list(d->d_inode, NULL, 0, name, name_len))
-			return (0);
 #endif
 	}
 
@@ -870,9 +867,8 @@ __zpl_xattr_security_set(struct inode *ip, const char *name,
 }
 ZPL_XATTR_SET_WRAPPER(zpl_xattr_security_set);
 
-#ifdef HAVE_CALLBACK_SECURITY_INODE_INIT_SECURITY
 static int
-__zpl_xattr_security_init(struct inode *ip, const struct xattr *xattrs,
+zpl_xattr_security_init_impl(struct inode *ip, const struct xattr *xattrs,
     void *fs_info)
 {
 	const struct xattr *xattr;
@@ -894,36 +890,8 @@ zpl_xattr_security_init(struct inode *ip, struct inode *dip,
     const struct qstr *qstr)
 {
 	return security_inode_init_security(ip, dip, qstr,
-	    &__zpl_xattr_security_init, NULL);
-}
-
-#else
-int
-zpl_xattr_security_init(struct inode *ip, struct inode *dip,
-    const struct qstr *qstr)
-{
-	int error;
-	size_t len;
-	void *value;
-	char *name;
-
-	error = zpl_security_inode_init_security(ip, dip, qstr,
-	    &name, &value, &len);
-	if (error) {
-		if (error == -EOPNOTSUPP)
-			return (0);
-
-		return (error);
-	}
-
-	error = __zpl_xattr_security_set(ip, name, value, len, 0);
-
-	kfree(name);
-	kfree(value);
-
-	return (error);
+	    &zpl_xattr_security_init_impl, NULL);
 }
-#endif /* HAVE_CALLBACK_SECURITY_INODE_INIT_SECURITY */
 
 /*
  * Security xattr namespace handlers.
@@ -958,7 +926,7 @@ zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type)
 	case ACL_TYPE_ACCESS:
 		name = XATTR_NAME_POSIX_ACL_ACCESS;
 		if (acl) {
-			zpl_equivmode_t mode = ip->i_mode;
+			umode_t mode = ip->i_mode;
 			error = posix_acl_equiv_mode(acl, &mode);
 			if (error < 0) {
 				return (error);
@@ -1073,53 +1041,6 @@ zpl_get_acl(struct inode *ip, int type)
 	return (acl);
 }
 
-#if !defined(HAVE_GET_ACL)
-static int
-__zpl_check_acl(struct inode *ip, int mask)
-{
-	struct posix_acl *acl;
-	int error;
-
-	acl = zpl_get_acl(ip, ACL_TYPE_ACCESS);
-	if (IS_ERR(acl))
-		return (PTR_ERR(acl));
-
-	if (acl) {
-		error = posix_acl_permission(ip, acl, mask);
-		zpl_posix_acl_release(acl);
-		return (error);
-	}
-
-	return (-EAGAIN);
-}
-
-#if defined(HAVE_CHECK_ACL_WITH_FLAGS)
-int
-zpl_check_acl(struct inode *ip, int mask, unsigned int flags)
-{
-	return (__zpl_check_acl(ip, mask));
-}
-#elif defined(HAVE_CHECK_ACL)
-int
-zpl_check_acl(struct inode *ip, int mask)
-{
-	return (__zpl_check_acl(ip, mask));
-}
-#elif defined(HAVE_PERMISSION_WITH_NAMEIDATA)
-int
-zpl_permission(struct inode *ip, int mask, struct nameidata *nd)
-{
-	return (generic_permission(ip, mask, __zpl_check_acl));
-}
-#elif defined(HAVE_PERMISSION)
-int
-zpl_permission(struct inode *ip, int mask)
-{
-	return (generic_permission(ip, mask, __zpl_check_acl));
-}
-#endif /* HAVE_CHECK_ACL | HAVE_PERMISSION */
-#endif /* !HAVE_GET_ACL */
-
 int
 zpl_init_acl(struct inode *ip, struct inode *dir)
 {
@@ -1295,7 +1216,7 @@ __zpl_xattr_acl_set_access(struct inode *ip, const char *name,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIXACL)
 		return (-EOPNOTSUPP);
 
-	if (!zpl_inode_owner_or_capable(ip))
+	if (!inode_owner_or_capable(ip))
 		return (-EPERM);
 
 	if (value) {
@@ -1335,7 +1256,7 @@ __zpl_xattr_acl_set_default(struct inode *ip, const char *name,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIXACL)
 		return (-EOPNOTSUPP);
 
-	if (!zpl_inode_owner_or_capable(ip))
+	if (!inode_owner_or_capable(ip))
 		return (-EPERM);
 
 	if (value) {
diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
index f1ed4f04e..2b1c82e67 100644
--- a/module/os/linux/zfs/zvol_os.c
+++ b/module/os/linux/zfs/zvol_os.c
@@ -392,9 +392,7 @@ zvol_request(struct request_queue *q, struct bio *bio)
 
 out:
 	spl_fstrans_unmark(cookie);
-#ifdef HAVE_MAKE_REQUEST_FN_RET_INT
-	return (0);
-#elif defined(HAVE_MAKE_REQUEST_FN_RET_QC)
+#if defined(HAVE_MAKE_REQUEST_FN_RET_QC)
 	return (BLK_QC_T_NONE);
 #endif
 }
@@ -480,11 +478,7 @@ out_mutex:
 	return (SET_ERROR(error));
 }
 
-#ifdef HAVE_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID
 static void
-#else
-static int
-#endif
 zvol_release(struct gendisk *disk, fmode_t mode)
 {
 	zvol_state_t *zv;
@@ -527,10 +521,6 @@ zvol_release(struct gendisk *disk, fmode_t mode)
 
 	if (drop_suspend)
 		rw_exit(&zv->zv_suspend_lock);
-
-#ifndef HAVE_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID
-	return (0);
-#endif
 }
 
 static int
@@ -579,10 +569,6 @@ zvol_compat_ioctl(struct block_device *bdev, fmode_t mode,
 #define	zvol_compat_ioctl	NULL
 #endif
 
-/*
- * Linux 2.6.38 preferred interface.
- */
-#ifdef HAVE_BLOCK_DEVICE_OPERATIONS_CHECK_EVENTS
 static unsigned int
 zvol_check_events(struct gendisk *disk, unsigned int clearing)
 {
@@ -602,27 +588,6 @@ zvol_check_events(struct gendisk *disk, unsigned int clearing)
 
 	return (mask);
 }
-#else
-static int
-zvol_media_changed(struct gendisk *disk)
-{
-	int changed = 0;
-
-	rw_enter(&zvol_state_lock, RW_READER);
-
-	zvol_state_t *zv = disk->private_data;
-	if (zv != NULL) {
-		mutex_enter(&zv->zv_state_lock);
-		changed = zv->zv_changed;
-		zv->zv_changed = 0;
-		mutex_exit(&zv->zv_state_lock);
-	}
-
-	rw_exit(&zvol_state_lock);
-
-	return (changed);
-}
-#endif
 
 static int
 zvol_revalidate_disk(struct gendisk *disk)
@@ -741,11 +706,7 @@ static struct block_device_operations zvol_ops = {
 	.release		= zvol_release,
 	.ioctl			= zvol_ioctl,
 	.compat_ioctl		= zvol_compat_ioctl,
-#ifdef HAVE_BLOCK_DEVICE_OPERATIONS_CHECK_EVENTS
 	.check_events		= zvol_check_events,
-#else
-	.media_changed		= zvol_media_changed,
-#endif
 	.revalidate_disk	= zvol_revalidate_disk,
 	.getgeo			= zvol_getgeo,
 	.owner			= THIS_MODULE,
@@ -803,9 +764,7 @@ zvol_alloc(dev_t dev, const char *name)
 	rw_init(&zv->zv_suspend_lock, NULL, RW_DEFAULT, NULL);
 
 	zv->zv_zso->zvo_disk->major = zvol_major;
-#ifdef HAVE_BLOCK_DEVICE_OPERATIONS_CHECK_EVENTS
 	zv->zv_zso->zvo_disk->events = DISK_EVENT_MEDIA_CHANGE;
-#endif
 
 	if (volmode == ZFS_VOLMODE_DEV) {
 		/*