Fix coverity defects: CID 147472

CID 147472: Type: 'Constant' variable guards dead code

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: cao.xuewen <[email protected]>
Closes #5288 

3 files changed, 15 insertions, 4 deletions

diff --git a/include/sys/dmu.h b/include/sys/dmu.h
index ec89e9018..9d61d94ee 100644
--- a/include/sys/dmu.h
+++ b/include/sys/dmu.h
@@ -744,6 +744,7 @@ struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
 void dmu_return_arcbuf(struct arc_buf *buf);
 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
     dmu_tx_t *tx);
+#ifdef HAVE_UIO_ZEROCOPY
 int dmu_xuio_init(struct xuio *uio, int niov);
 void dmu_xuio_fini(struct xuio *uio);
 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
@@ -751,6 +752,7 @@ int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
 int dmu_xuio_cnt(struct xuio *uio);
 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
 void dmu_xuio_clear(struct xuio *uio, int i);
+#endif /* HAVE_UIO_ZEROCOPY */
 void xuio_stat_wbuf_copied(void);
 void xuio_stat_wbuf_nocopy(void);
 
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 80185706c..7da49af7b 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -987,6 +987,7 @@ static xuio_stats_t xuio_stats = {
 	atomic_add_64(&xuio_stats.stat.value.ui64, (val))
 #define	XUIOSTAT_BUMP(stat)	XUIOSTAT_INCR(stat, 1)
 
+#ifdef HAVE_UIO_ZEROCOPY
 int
 dmu_xuio_init(xuio_t *xuio, int nblk)
 {
@@ -1071,6 +1072,7 @@ dmu_xuio_clear(xuio_t *xuio, int i)
 	ASSERT(i < priv->cnt);
 	priv->bufs[i] = NULL;
 }
+#endif /* HAVE_UIO_ZEROCOPY */
 
 static void
 xuio_stat_init(void)
@@ -1111,7 +1113,9 @@ dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
 {
 	dmu_buf_t **dbp;
 	int numbufs, i, err;
+#ifdef HAVE_UIO_ZEROCOPY
 	xuio_t *xuio = NULL;
+#endif
 
 	/*
 	 * NB: we could do this block-at-a-time, but it's nice
@@ -1132,6 +1136,7 @@ dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
 		bufoff = uio->uio_loffset - db->db_offset;
 		tocpy = MIN(db->db_size - bufoff, size);
 
+#ifdef HAVE_UIO_ZEROCOPY
 		if (xuio) {
 			dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
 			arc_buf_t *dbuf_abuf = dbi->db_buf;
@@ -1146,10 +1151,10 @@ dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
 				XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
 			else
 				XUIOSTAT_BUMP(xuiostat_rbuf_copied);
-		} else {
+		} else
+#endif
 			err = uiomove((char *)db->db_data + bufoff, tocpy,
 			    UIO_READ, uio);
-		}
 		if (err)
 			break;
 
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 116bb2730..8ac14df00 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -596,14 +596,16 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 	arc_buf_t	*abuf;
 	const iovec_t	*aiov = NULL;
 	xuio_t		*xuio = NULL;
-	int		i_iov = 0;
-	const iovec_t	*iovp = uio->uio_iov;
 	int		write_eof;
 	int		count = 0;
 	sa_bulk_attr_t	bulk[4];
 	uint64_t	mtime[2], ctime[2];
 	uint32_t	uid;
+#ifdef HAVE_UIO_ZEROCOPY
+	int		i_iov = 0;
+	const iovec_t	*iovp = uio->uio_iov;
 	ASSERTV(int	iovcnt = uio->uio_iovcnt);
+#endif
 
 	/*
 	 * Fasttrack empty write
@@ -726,6 +728,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		}
 
 		if (xuio && abuf == NULL) {
+#ifdef HAVE_UIO_ZEROCOPY
 			ASSERT(i_iov < iovcnt);
 			ASSERT3U(uio->uio_segflg, !=, UIO_BVEC);
 			aiov = &iovp[i_iov];
@@ -735,6 +738,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 			    ((char *)aiov->iov_base - (char *)abuf->b_data +
 			    aiov->iov_len == arc_buf_size(abuf)));
 			i_iov++;
+#endif
 		} else if (abuf == NULL && n >= max_blksz &&
 		    woff >= zp->z_size &&
 		    P2PHASE(woff, max_blksz) == 0 &&