module/*.ko: prune .data, global .rodata

Evaluated every variable that lives in .data (and globals in .rodata)
in the kernel modules, and constified/eliminated/localised them
appropriately. This means that all read-only data is now actually
read-only data, and, if possible, at file scope. A lot of previously-
global-symbols became inlinable (and inlined!) constants. Probably
not in a big Wowee Performance Moment, but hey.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12899

module/os/linux/zfs/abd_os.c

@@ -149,8 +149,6 @@ struct {
 #define	abd_for_each_sg(abd, sg, n, i)	\
 	for_each_sg(ABD_SCATTER(abd).abd_sgl, sg, n, i)
 
-unsigned zfs_abd_scatter_max_order = MAX_ORDER - 1;
-
 /*
  * zfs_abd_scatter_min_size is the minimum allocation size to use scatter
  * ABD's.  Smaller allocations will use linear ABD's which uses
@@ -173,7 +171,7 @@ unsigned zfs_abd_scatter_max_order = MAX_ORDER - 1;
  * By default we use linear allocations for 512B and 1KB, and scatter
  * allocations for larger (1.5KB and up).
  */
-int zfs_abd_scatter_min_size = 512 * 3;
+static int zfs_abd_scatter_min_size = 512 * 3;
 
 /*
  * We use a scattered SPA_MAXBLOCKSIZE sized ABD whose pages are
@@ -221,6 +219,8 @@ abd_free_struct_impl(abd_t *abd)
 }
 
 #ifdef _KERNEL
+static unsigned zfs_abd_scatter_max_order = MAX_ORDER - 1;
+
 /*
  * Mark zfs data pages so they can be excluded from kernel crash dumps
  */

module/os/linux/zfs/vdev_disk.c

@@ -919,7 +919,7 @@ param_set_vdev_scheduler(const char *val, zfs_kernel_param_t *kp)
 	return (error);
 }
 
-char *zfs_vdev_scheduler = "unused";
+static const char *zfs_vdev_scheduler = "unused";
 module_param_call(zfs_vdev_scheduler, param_set_vdev_scheduler,
     param_get_charp, &zfs_vdev_scheduler, 0644);
 MODULE_PARM_DESC(zfs_vdev_scheduler, "I/O scheduler");

module/os/linux/zfs/vdev_file.c

@@ -53,8 +53,8 @@ static taskq_t *vdev_file_taskq;
  * impact the vdev_ashift setting which can only be set at vdev creation
  * time.
  */
-unsigned long vdev_file_logical_ashift = SPA_MINBLOCKSHIFT;
-unsigned long vdev_file_physical_ashift = SPA_MINBLOCKSHIFT;
+static unsigned long vdev_file_logical_ashift = SPA_MINBLOCKSHIFT;
+static unsigned long vdev_file_physical_ashift = SPA_MINBLOCKSHIFT;
 
 static void
 vdev_file_hold(vdev_t *vd)

module/os/linux/zfs/zfs_acl.c

@@ -171,7 +171,7 @@ zfs_ace_v0_data(void *acep, void **datap)
 	return (0);
 }
 
-static acl_ops_t zfs_acl_v0_ops = {
+static const acl_ops_t zfs_acl_v0_ops = {
 	.ace_mask_get = zfs_ace_v0_get_mask,
 	.ace_mask_set = zfs_ace_v0_set_mask,
 	.ace_flags_get = zfs_ace_v0_get_flags,
@@ -307,7 +307,7 @@ zfs_ace_fuid_data(void *acep, void **datap)
 	}
 }
 
-static acl_ops_t zfs_acl_fuid_ops = {
+static const acl_ops_t zfs_acl_fuid_ops = {
 	.ace_mask_get = zfs_ace_fuid_get_mask,
 	.ace_mask_set = zfs_ace_fuid_set_mask,
 	.ace_flags_get = zfs_ace_fuid_get_flags,
@@ -2702,7 +2702,7 @@ zfs_zaccess_unix(znode_t *zp, mode_t mode, cred_t *cr)
 }
 
 /* See zfs_zaccess_delete() */
-int zfs_write_implies_delete_child = 1;
+static const boolean_t zfs_write_implies_delete_child = B_TRUE;
 
 /*
  * Determine whether delete access should be granted.

module/os/linux/zfs/zfs_ctldir.c

@@ -110,7 +110,7 @@ static krwlock_t zfs_snapshot_lock;
  * Control Directory Tunables (.zfs)
  */
 int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT;
-int zfs_admin_snapshot = 0;
+static int zfs_admin_snapshot = 0;
 
 typedef struct {
 	char		*se_name;	/* full snapshot name */

module/os/linux/zfs/zfs_debug.c

@@ -33,8 +33,8 @@ typedef struct zfs_dbgmsg {
 	char			zdm_msg[1]; /* variable length allocation */
 } zfs_dbgmsg_t;
 
-procfs_list_t zfs_dbgmsgs;
-int zfs_dbgmsg_size = 0;
+static procfs_list_t zfs_dbgmsgs;
+static int zfs_dbgmsg_size = 0;
 int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
 
 /*
@@ -49,7 +49,7 @@ int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  * # Clear the kernel debug message log.
  * echo 0 >/proc/spl/kstat/zfs/dbgmsg
  */
-int zfs_dbgmsg_enable = 1;
+int zfs_dbgmsg_enable = B_TRUE;
 
 static int
 zfs_dbgmsg_show_header(struct seq_file *f)

module/os/linux/zfs/zfs_vnops_os.c

@@ -320,7 +320,7 @@ mappedread(znode_t *zp, int nbytes, zfs_uio_t *uio)
 }
 #endif /* _KERNEL */
 
-unsigned long zfs_delete_blocks = DMU_MAX_DELETEBLKCNT;
+static unsigned long zfs_delete_blocks = DMU_MAX_DELETEBLKCNT;
 
 /*
  * Write the bytes to a file.

module/os/linux/zfs/zfs_znode.c

@@ -80,7 +80,7 @@ unsigned int zfs_object_mutex_size = ZFS_OBJ_MTX_SZ;
  * This is used by the test suite so that it can delay znodes from being
  * freed in order to inspect the unlinked set.
  */
-int zfs_unlink_suspend_progress = 0;
+static int zfs_unlink_suspend_progress = 0;
 
 /*
  * This callback is invoked when acquiring a RL_WRITER or RL_APPEND lock on

module/os/linux/zfs/zio_crypt.c

@@ -186,7 +186,7 @@
 #define	ZFS_KEY_MAX_SALT_USES_DEFAULT	400000000
 #define	ZFS_CURRENT_MAX_SALT_USES	\
 	(MIN(zfs_key_max_salt_uses, ZFS_KEY_MAX_SALT_USES_DEFAULT))
-unsigned long zfs_key_max_salt_uses = ZFS_KEY_MAX_SALT_USES_DEFAULT;
+static unsigned long zfs_key_max_salt_uses = ZFS_KEY_MAX_SALT_USES_DEFAULT;
 
 typedef struct blkptr_auth_buf {
 	uint64_t bab_prop;			/* blk_prop - portable mask */
@@ -194,7 +194,7 @@ typedef struct blkptr_auth_buf {
 	uint64_t bab_pad;			/* reserved for future use */
 } blkptr_auth_buf_t;
 
-zio_crypt_info_t zio_crypt_table[ZIO_CRYPT_FUNCTIONS] = {
+const zio_crypt_info_t zio_crypt_table[ZIO_CRYPT_FUNCTIONS] = {
 	{"",			ZC_TYPE_NONE,	0,	"inherit"},
 	{"",			ZC_TYPE_NONE,	0,	"on"},
 	{"",			ZC_TYPE_NONE,	0,	"off"},

module/os/linux/zfs/zpl_ctldir.c

@@ -201,7 +201,7 @@ zpl_snapdir_revalidate(struct dentry *dentry, unsigned int flags)
 	return (!!dentry->d_inode);
 }
 
-dentry_operations_t zpl_dops_snapdirs = {
+static const dentry_operations_t zpl_dops_snapdirs = {
 /*
  * Auto mounting of snapshots is only supported for 2.6.37 and
  * newer kernels.  Prior to this kernel the ops->follow_link()

module/os/linux/zfs/zpl_file.c

@@ -41,7 +41,7 @@
  * When using fallocate(2) to preallocate space, inflate the requested
  * capacity check by 10% to account for the required metadata blocks.
  */
-unsigned int zfs_fallocate_reserve_percent = 110;
+static unsigned int zfs_fallocate_reserve_percent = 110;
 
 static int
 zpl_open(struct inode *ip, struct file *filp)

module/os/linux/zfs/zpl_xattr.c

@@ -746,7 +746,7 @@ __zpl_xattr_user_set(struct inode *ip, const char *name,
 }
 ZPL_XATTR_SET_WRAPPER(zpl_xattr_user_set);
 
-xattr_handler_t zpl_xattr_user_handler =
+static xattr_handler_t zpl_xattr_user_handler =
 {
 	.prefix	= XATTR_USER_PREFIX,
 	.list	= zpl_xattr_user_list,
@@ -815,8 +815,7 @@ __zpl_xattr_trusted_set(struct inode *ip, const char *name,
 }
 ZPL_XATTR_SET_WRAPPER(zpl_xattr_trusted_set);
 
-xattr_handler_t zpl_xattr_trusted_handler =
-{
+static xattr_handler_t zpl_xattr_trusted_handler = {
 	.prefix	= XATTR_TRUSTED_PREFIX,
 	.list	= zpl_xattr_trusted_list,
 	.get	= zpl_xattr_trusted_get,
@@ -910,7 +909,7 @@ zpl_xattr_security_init(struct inode *ip, struct inode *dip,
 /*
  * Security xattr namespace handlers.
  */
-xattr_handler_t zpl_xattr_security_handler = {
+static xattr_handler_t zpl_xattr_security_handler = {
 	.prefix	= XATTR_SECURITY_PREFIX,
 	.list	= zpl_xattr_security_list,
 	.get	= zpl_xattr_security_get,
@@ -1333,8 +1332,7 @@ ZPL_XATTR_SET_WRAPPER(zpl_xattr_acl_set_default);
  * Use .name instead of .prefix when available. xattr_resolve_name will match
  * whole name and reject anything that has .name only as prefix.
  */
-xattr_handler_t zpl_xattr_acl_access_handler =
-{
+static xattr_handler_t zpl_xattr_acl_access_handler = {
 #ifdef HAVE_XATTR_HANDLER_NAME
 	.name	= XATTR_NAME_POSIX_ACL_ACCESS,
 #else
@@ -1356,8 +1354,7 @@ xattr_handler_t zpl_xattr_acl_access_handler =
  * Use .name instead of .prefix when available. xattr_resolve_name will match
  * whole name and reject anything that has .name only as prefix.
  */
-xattr_handler_t zpl_xattr_acl_default_handler =
-{
+static xattr_handler_t zpl_xattr_acl_default_handler = {
 #ifdef HAVE_XATTR_HANDLER_NAME
 	.name	= XATTR_NAME_POSIX_ACL_DEFAULT,
 #else

module/os/linux/zfs/zvol_os.c

@@ -41,12 +41,12 @@
 #include <linux/blkdev_compat.h>
 #include <linux/task_io_accounting_ops.h>
 
-unsigned int zvol_major = ZVOL_MAJOR;
-unsigned int zvol_request_sync = 0;
-unsigned int zvol_prefetch_bytes = (128 * 1024);
-unsigned long zvol_max_discard_blocks = 16384;
-unsigned int zvol_threads = 32;
-unsigned int zvol_open_timeout_ms = 1000;
+static unsigned int zvol_major = ZVOL_MAJOR;
+static unsigned int zvol_request_sync = 0;
+static unsigned int zvol_prefetch_bytes = (128 * 1024);
+static unsigned long zvol_max_discard_blocks = 16384;
+static unsigned int zvol_threads = 32;
+static const unsigned int zvol_open_timeout_ms = 1000;
 
 struct zvol_state_os {
 	struct gendisk		*zvo_disk;	/* generic disk */
@@ -802,7 +802,7 @@ zvol_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	return (0);
 }
 
-static struct block_device_operations zvol_ops = {
+static const struct block_device_operations zvol_ops = {
 	.open			= zvol_open,
 	.release		= zvol_release,
 	.ioctl			= zvol_ioctl,