Linux 4.18 compat: inode timespec -> timespec64

Commit torvalds/linux@95582b0 changes the inode i_atime, i_mtime,
and i_ctime members form timespec's to timespec64's to make them
2038 safe.  As part of this change the current_time() function was
also updated to return the timespec64 type.

Resolve this issue by introducing a new inode_timespec_t type which
is defined to match the timespec type used by the inode.  It should
be used when working with inode timestamps to ensure matching types.

The timestruc_t type under Illumos was used in a similar fashion but
was specified to always be a timespec_t.  Rather than incorrectly
define this type all timespec_t types have been replaced by the new
inode_timespec_t type.

Finally, the kernel and user space 'sys/time.h' headers were aligned
with each other.  They define as appropriate for the context several
constants as macros and include static inline implementation of
gethrestime(), gethrestime_sec(), and gethrtime().

Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7643

module/zfs/dmu_objset.c

@@ -965,7 +965,7 @@ dmu_objset_evict_done(objset_t *os)
 	kmem_free(os, sizeof (objset_t));
 }
 
-timestruc_t
+inode_timespec_t
 dmu_objset_snap_cmtime(objset_t *os)
 {
 	return (dsl_dir_snap_cmtime(os->os_dsl_dataset->ds_dir));

module/zfs/dsl_dir.c

@@ -2126,10 +2126,10 @@ dsl_dir_transfer_possible(dsl_dir_t *sdd, dsl_dir_t *tdd,
 	return (0);
 }
 
-timestruc_t
+inode_timespec_t
 dsl_dir_snap_cmtime(dsl_dir_t *dd)
 {
-	timestruc_t t;
+	inode_timespec_t t;
 
 	mutex_enter(&dd->dd_lock);
 	t = dd->dd_snap_cmtime;
@@ -2141,7 +2141,7 @@ dsl_dir_snap_cmtime(dsl_dir_t *dd)
 void
 dsl_dir_snap_cmtime_update(dsl_dir_t *dd)
 {
-	timestruc_t t;
+	inode_timespec_t t;
 
 	gethrestime(&t);
 	mutex_enter(&dd->dd_lock);

module/zfs/fm.c

@@ -503,8 +503,8 @@ zfs_zevent_insert(zevent_t *ev)
 int
 zfs_zevent_post(nvlist_t *nvl, nvlist_t *detector, zevent_cb_t *cb)
 {
+	inode_timespec_t tv;
 	int64_t tv_array[2];
-	timestruc_t tv;
 	uint64_t eid;
 	size_t nvl_size = 0;
 	zevent_t *ev;

module/zfs/zfs_ctldir.c

@@ -448,7 +448,7 @@ static struct inode *
 zfsctl_inode_alloc(zfsvfs_t *zfsvfs, uint64_t id,
     const struct file_operations *fops, const struct inode_operations *ops)
 {
-	struct timespec now;
+	inode_timespec_t now;
 	struct inode *ip;
 	znode_t *zp;
 

module/zfs/zfs_vnops.c

@@ -3408,7 +3408,7 @@ top:
 
 	if (mask & (ATTR_MTIME | ATTR_SIZE)) {
 		ZFS_TIME_ENCODE(&vap->va_mtime, mtime);
-		ZTOI(zp)->i_mtime = timespec_trunc(vap->va_mtime,
+		ZTOI(zp)->i_mtime = zpl_inode_timespec_trunc(vap->va_mtime,
 		    ZTOI(zp)->i_sb->s_time_gran);
 
 		SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
@@ -3417,7 +3417,7 @@ top:
 
 	if (mask & (ATTR_CTIME | ATTR_SIZE)) {
 		ZFS_TIME_ENCODE(&vap->va_ctime, ctime);
-		ZTOI(zp)->i_ctime = timespec_trunc(vap->va_ctime,
+		ZTOI(zp)->i_ctime = zpl_inode_timespec_trunc(vap->va_ctime,
 		    ZTOI(zp)->i_sb->s_time_gran);
 		SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 		    ctime, sizeof (ctime));

module/zfs/zfs_znode.c

@@ -698,7 +698,7 @@ zfs_mknode(znode_t *dzp, vattr_t *vap, dmu_tx_t *tx, cred_t *cr,
 	uint64_t	rdev = 0;
 	zfsvfs_t	*zfsvfs = ZTOZSB(dzp);
 	dmu_buf_t	*db;
-	timestruc_t	now;
+	inode_timespec_t now;
 	uint64_t	gen, obj;
 	int		bonuslen;
 	int		dnodesize;
@@ -1403,7 +1403,7 @@ void
 zfs_tstamp_update_setup(znode_t *zp, uint_t flag, uint64_t mtime[2],
     uint64_t ctime[2])
 {
-	timestruc_t	now;
+	inode_timespec_t now;
 
 	gethrestime(&now);
 

module/zfs/zpl_inode.c

@@ -384,9 +384,10 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
 	vap->va_mtime = ia->ia_mtime;
 	vap->va_ctime = ia->ia_ctime;
 
-	if (vap->va_mask & ATTR_ATIME)
-		ip->i_atime = timespec_trunc(ia->ia_atime,
+	if (vap->va_mask & ATTR_ATIME) {
+		ip->i_atime = zpl_inode_timespec_trunc(ia->ia_atime,
 		    ip->i_sb->s_time_gran);
+	}
 
 	cookie = spl_fstrans_mark();
 	error = -zfs_setattr(ip, vap, 0, cr);