Remove UIO_ZEROCOPY functions structures

The original xuio zero copy functionality has always been unused 
on Linux and FreeBSD.  Remove this disabled code to avoid any
confusion and improve readability.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #11124 

9 files changed, 0 insertions, 454 deletions

diff --git a/cmd/arc_summary/arc_summary3 b/cmd/arc_summary/arc_summary3
index a16086416..c33ee2578 100755
--- a/cmd/arc_summary/arc_summary3
+++ b/cmd/arc_summary/arc_summary3
@@ -58,7 +58,6 @@ SECTION_PATHS = {'arc': 'arcstats',
                  'dmu': 'dmu_tx',
                  'l2arc': 'arcstats',  # L2ARC stuff lives in arcstats
                  'vdev': 'vdev_cache_stats',
-                 'xuio': 'xuio_stats',
                  'zfetch': 'zfetchstats',
                  'zil': 'zil'}
 
diff --git a/include/os/freebsd/spl/sys/uio.h b/include/os/freebsd/spl/sys/uio.h
index d9dab652c..81c7ab64c 100644
--- a/include/os/freebsd/spl/sys/uio.h
+++ b/include/os/freebsd/spl/sys/uio.h
@@ -43,27 +43,6 @@ typedef	struct uio	uio_t;
 typedef	struct iovec	iovec_t;
 typedef	enum uio_seg	uio_seg_t;
 
-typedef enum xuio_type {
-	UIOTYPE_ASYNCIO,
-	UIOTYPE_ZEROCOPY
-} xuio_type_t;
-
-typedef struct xuio {
-	uio_t	xu_uio;
-
-	/* Extended uio fields */
-	enum xuio_type xu_type; /* What kind of uio structure? */
-	union {
-		struct {
-			int xu_zc_rw;
-			void *xu_zc_priv;
-		} xu_zc;
-	} xu_ext;
-} xuio_t;
-
-#define	XUIO_XUZC_PRIV(xuio)	xuio->xu_ext.xu_zc.xu_zc_priv
-#define	XUIO_XUZC_RW(xuio)	xuio->xu_ext.xu_zc.xu_zc_rw
-
 static __inline int
 zfs_uiomove(void *cp, size_t n, enum uio_rw dir, uio_t *uio)
 {
diff --git a/include/os/linux/spl/sys/uio.h b/include/os/linux/spl/sys/uio.h
index 4e7b488c5..6e850c5fe 100644
--- a/include/os/linux/spl/sys/uio.h
+++ b/include/os/linux/spl/sys/uio.h
@@ -68,49 +68,6 @@ typedef struct uio {
 	size_t		uio_skip;
 } uio_t;
 
-typedef struct aio_req {
-	uio_t		*aio_uio;
-	void		*aio_private;
-} aio_req_t;
-
-typedef enum xuio_type {
-	UIOTYPE_ASYNCIO,
-	UIOTYPE_ZEROCOPY,
-} xuio_type_t;
-
-
-#define	UIOA_IOV_MAX    16
-
-typedef struct uioa_page_s {
-	int	uioa_pfncnt;
-	void	**uioa_ppp;
-	caddr_t	uioa_base;
-	size_t	uioa_len;
-} uioa_page_t;
-
-typedef struct xuio {
-	uio_t xu_uio;
-	enum xuio_type xu_type;
-	union {
-		struct {
-			uint32_t xu_a_state;
-			ssize_t xu_a_mbytes;
-			uioa_page_t *xu_a_lcur;
-			void **xu_a_lppp;
-			void *xu_a_hwst[4];
-			uioa_page_t xu_a_locked[UIOA_IOV_MAX];
-		} xu_aio;
-
-		struct {
-			int xu_zc_rw;
-			void *xu_zc_priv;
-		} xu_zc;
-	} xu_ext;
-} xuio_t;
-
-#define	XUIO_XUZC_PRIV(xuio)	xuio->xu_ext.xu_zc.xu_zc_priv
-#define	XUIO_XUZC_RW(xuio)	xuio->xu_ext.xu_zc.xu_zc_rw
-
 #define	uio_segflg(uio)			(uio)->uio_segflg
 #define	uio_offset(uio)			(uio)->uio_loffset
 #define	uio_resid(uio)			(uio)->uio_resid
diff --git a/include/sys/dmu.h b/include/sys/dmu.h
index 54fdbc9ad..0c50d0409 100644
--- a/include/sys/dmu.h
+++ b/include/sys/dmu.h
@@ -864,18 +864,6 @@ int dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset,
 int dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset,
     struct arc_buf *buf, dmu_tx_t *tx);
 #define	dmu_assign_arcbuf	dmu_assign_arcbuf_by_dbuf
-#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,
-    size_t n);
-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);
-
 extern int zfs_prefetch_disable;
 extern int zfs_max_recordsize;
 
diff --git a/include/sys/dmu_impl.h b/include/sys/dmu_impl.h
index 0c6273a3a..def4aadba 100644
--- a/include/sys/dmu_impl.h
+++ b/include/sys/dmu_impl.h
@@ -237,13 +237,6 @@ extern "C" {
 struct objset;
 struct dmu_pool;
 
-typedef struct dmu_xuio {
-	int next;
-	int cnt;
-	struct arc_buf **bufs;
-	iovec_t *iovp;
-} dmu_xuio_t;
-
 typedef struct dmu_sendstatus {
 	list_node_t dss_link;
 	int dss_outfd;
diff --git a/lib/libspl/include/sys/uio.h b/lib/libspl/include/sys/uio.h
index 2fbb712d6..1d56b5b18 100644
--- a/lib/libspl/include/sys/uio.h
+++ b/lib/libspl/include/sys/uio.h
@@ -75,45 +75,6 @@ typedef struct uio {
 	ssize_t		uio_resid;	/* residual count */
 } uio_t;
 
-typedef enum xuio_type {
-	UIOTYPE_ASYNCIO,
-	UIOTYPE_ZEROCOPY,
-} xuio_type_t;
-
-#define	UIOA_IOV_MAX	16
-
-typedef struct uioa_page_s {		/* locked uio_iov state */
-	int	uioa_pfncnt;		/* count of pfn_t(s) in *uioa_ppp */
-	void	**uioa_ppp;		/* page_t or pfn_t array */
-	caddr_t	uioa_base;		/* address base */
-	size_t	uioa_len;		/* span length */
-} uioa_page_t;
-
-typedef struct xuio {
-	uio_t xu_uio;				/* embedded UIO structure */
-
-	/* Extended uio fields */
-	enum xuio_type xu_type;			/* uio type */
-	union {
-		struct {
-			uint32_t xu_a_state;	/* state of async i/o */
-			ssize_t xu_a_mbytes;	/* bytes moved */
-			uioa_page_t *xu_a_lcur;	/* uioa_locked[] pointer */
-			void **xu_a_lppp;	/* lcur->uioa_pppp[] pointer */
-			void *xu_a_hwst[4];	/* opaque hardware state */
-			uioa_page_t xu_a_locked[UIOA_IOV_MAX];
-		} xu_aio;
-
-		struct {
-			int xu_zc_rw;		/* read or write buffer */
-			void *xu_zc_priv;	/* fs specific */
-		} xu_zc;
-	} xu_ext;
-} xuio_t;
-
-#define	XUIO_XUZC_PRIV(xuio)	xuio->xu_ext.xu_zc.xu_zc_priv
-#define	XUIO_XUZC_RW(xuio)	xuio->xu_ext.xu_zc.xu_zc_rw
-
 #define	uio_segflg(uio)			(uio)->uio_segflg
 #define	uio_offset(uio)			(uio)->uio_loffset
 #define	uio_resid(uio)			(uio)->uio_resid
diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index 75f33fad7..466fac3f3 100644
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -3978,164 +3978,6 @@ zfs_fid(struct inode *ip, fid_t *fidp)
 	return (0);
 }
 
-#ifdef HAVE_UIO_ZEROCOPY
-/*
- * The smallest read we may consider to loan out an arcbuf.
- * This must be a power of 2.
- */
-int zcr_blksz_min = (1 << 10);	/* 1K */
-/*
- * If set to less than the file block size, allow loaning out of an
- * arcbuf for a partial block read.  This must be a power of 2.
- */
-int zcr_blksz_max = (1 << 17);	/* 128K */
-
-
-/*ARGSUSED*/
-static int
-zfs_reqzcbuf(struct inode *ip, enum uio_rw ioflag, xuio_t *xuio, cred_t *cr)
-{
-	znode_t	*zp = ITOZ(ip);
-	zfsvfs_t *zfsvfs = ITOZSB(ip);
-	int max_blksz = zfsvfs->z_max_blksz;
-	uio_t *uio = &xuio->xu_uio;
-	ssize_t size = uio->uio_resid;
-	offset_t offset = uio->uio_loffset;
-	int blksz;
-	int fullblk, i;
-	arc_buf_t *abuf;
-	ssize_t maxsize;
-	int preamble, postamble;
-
-	if (xuio->xu_type != UIOTYPE_ZEROCOPY)
-		return (SET_ERROR(EINVAL));
-
-	ZFS_ENTER(zfsvfs);
-	ZFS_VERIFY_ZP(zp);
-	switch (ioflag) {
-	case UIO_WRITE:
-		/*
-		 * Loan out an arc_buf for write if write size is bigger than
-		 * max_blksz, and the file's block size is also max_blksz.
-		 */
-		blksz = max_blksz;
-		if (size < blksz || zp->z_blksz != blksz) {
-			ZFS_EXIT(zfsvfs);
-			return (SET_ERROR(EINVAL));
-		}
-		/*
-		 * Caller requests buffers for write before knowing where the
-		 * write offset might be (e.g. NFS TCP write).
-		 */
-		if (offset == -1) {
-			preamble = 0;
-		} else {
-			preamble = P2PHASE(offset, blksz);
-			if (preamble) {
-				preamble = blksz - preamble;
-				size -= preamble;
-			}
-		}
-
-		postamble = P2PHASE(size, blksz);
-		size -= postamble;
-
-		fullblk = size / blksz;
-		(void) dmu_xuio_init(xuio,
-		    (preamble != 0) + fullblk + (postamble != 0));
-
-		/*
-		 * Have to fix iov base/len for partial buffers.  They
-		 * currently represent full arc_buf's.
-		 */
-		if (preamble) {
-			/* data begins in the middle of the arc_buf */
-			abuf = dmu_request_arcbuf(sa_get_db(zp->z_sa_hdl),
-			    blksz);
-			ASSERT(abuf);
-			(void) dmu_xuio_add(xuio, abuf,
-			    blksz - preamble, preamble);
-		}
-
-		for (i = 0; i < fullblk; i++) {
-			abuf = dmu_request_arcbuf(sa_get_db(zp->z_sa_hdl),
-			    blksz);
-			ASSERT(abuf);
-			(void) dmu_xuio_add(xuio, abuf, 0, blksz);
-		}
-
-		if (postamble) {
-			/* data ends in the middle of the arc_buf */
-			abuf = dmu_request_arcbuf(sa_get_db(zp->z_sa_hdl),
-			    blksz);
-			ASSERT(abuf);
-			(void) dmu_xuio_add(xuio, abuf, 0, postamble);
-		}
-		break;
-	case UIO_READ:
-		/*
-		 * Loan out an arc_buf for read if the read size is larger than
-		 * the current file block size.  Block alignment is not
-		 * considered.  Partial arc_buf will be loaned out for read.
-		 */
-		blksz = zp->z_blksz;
-		if (blksz < zcr_blksz_min)
-			blksz = zcr_blksz_min;
-		if (blksz > zcr_blksz_max)
-			blksz = zcr_blksz_max;
-		/* avoid potential complexity of dealing with it */
-		if (blksz > max_blksz) {
-			ZFS_EXIT(zfsvfs);
-			return (SET_ERROR(EINVAL));
-		}
-
-		maxsize = zp->z_size - uio->uio_loffset;
-		if (size > maxsize)
-			size = maxsize;
-
-		if (size < blksz) {
-			ZFS_EXIT(zfsvfs);
-			return (SET_ERROR(EINVAL));
-		}
-		break;
-	default:
-		ZFS_EXIT(zfsvfs);
-		return (SET_ERROR(EINVAL));
-	}
-
-	uio->uio_extflg = UIO_XUIO;
-	XUIO_XUZC_RW(xuio) = ioflag;
-	ZFS_EXIT(zfsvfs);
-	return (0);
-}
-
-/*ARGSUSED*/
-static int
-zfs_retzcbuf(struct inode *ip, xuio_t *xuio, cred_t *cr)
-{
-	int i;
-	arc_buf_t *abuf;
-	int ioflag = XUIO_XUZC_RW(xuio);
-
-	ASSERT(xuio->xu_type == UIOTYPE_ZEROCOPY);
-
-	i = dmu_xuio_cnt(xuio);
-	while (i-- > 0) {
-		abuf = dmu_xuio_arcbuf(xuio, i);
-		/*
-		 * if abuf == NULL, it must be a write buffer
-		 * that has been returned in zfs_write().
-		 */
-		if (abuf)
-			dmu_return_arcbuf(abuf);
-		ASSERT(abuf || ioflag == UIO_WRITE);
-	}
-
-	dmu_xuio_fini(xuio);
-	return (0);
-}
-#endif /* HAVE_UIO_ZEROCOPY */
-
 #if defined(_KERNEL)
 EXPORT_SYMBOL(zfs_open);
 EXPORT_SYMBOL(zfs_close);
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 844f69367..d71920c48 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -2617,11 +2617,9 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
 		(void) dbuf_dirty(db, tx);
 		bcopy(buf->b_data, db->db.db_data, db->db.db_size);
 		arc_buf_destroy(buf, db);
-		xuio_stat_wbuf_copied();
 		return;
 	}
 
-	xuio_stat_wbuf_nocopy();
 	if (db->db_state == DB_CACHED) {
 		dbuf_dirty_record_t *dr = list_head(&db->db_dirty_records);
 
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index d681fe3fe..c54762526 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -1169,165 +1169,12 @@ dmu_redact(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 	dmu_buf_rele_array(dbp, numbufs, FTAG);
 }
 
-/*
- * DMU support for xuio
- */
-kstat_t *xuio_ksp = NULL;
-
-typedef struct xuio_stats {
-	/* loaned yet not returned arc_buf */
-	kstat_named_t xuiostat_onloan_rbuf;
-	kstat_named_t xuiostat_onloan_wbuf;
-	/* whether a copy is made when loaning out a read buffer */
-	kstat_named_t xuiostat_rbuf_copied;
-	kstat_named_t xuiostat_rbuf_nocopy;
-	/* whether a copy is made when assigning a write buffer */
-	kstat_named_t xuiostat_wbuf_copied;
-	kstat_named_t xuiostat_wbuf_nocopy;
-} xuio_stats_t;
-
-static xuio_stats_t xuio_stats = {
-	{ "onloan_read_buf",	KSTAT_DATA_UINT64 },
-	{ "onloan_write_buf",	KSTAT_DATA_UINT64 },
-	{ "read_buf_copied",	KSTAT_DATA_UINT64 },
-	{ "read_buf_nocopy",	KSTAT_DATA_UINT64 },
-	{ "write_buf_copied",	KSTAT_DATA_UINT64 },
-	{ "write_buf_nocopy",	KSTAT_DATA_UINT64 }
-};
-
-#define	XUIOSTAT_INCR(stat, val)        \
-	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)
-{
-	dmu_xuio_t *priv;
-	uio_t *uio = &xuio->xu_uio;
-
-	uio->uio_iovcnt = nblk;
-	uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
-
-	priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
-	priv->cnt = nblk;
-	priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
-	priv->iovp = (iovec_t *)uio->uio_iov;
-	XUIO_XUZC_PRIV(xuio) = priv;
-
-	if (XUIO_XUZC_RW(xuio) == UIO_READ)
-		XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
-	else
-		XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
-
-	return (0);
-}
-
-void
-dmu_xuio_fini(xuio_t *xuio)
-{
-	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
-	int nblk = priv->cnt;
-
-	kmem_free(priv->iovp, nblk * sizeof (iovec_t));
-	kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
-	kmem_free(priv, sizeof (dmu_xuio_t));
-
-	if (XUIO_XUZC_RW(xuio) == UIO_READ)
-		XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
-	else
-		XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
-}
-
-/*
- * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
- * and increase priv->next by 1.
- */
-int
-dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
-{
-	struct iovec *iov;
-	uio_t *uio = &xuio->xu_uio;
-	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
-	int i = priv->next++;
-
-	ASSERT(i < priv->cnt);
-	ASSERT(off + n <= arc_buf_lsize(abuf));
-	iov = (iovec_t *)uio->uio_iov + i;
-	iov->iov_base = (char *)abuf->b_data + off;
-	iov->iov_len = n;
-	priv->bufs[i] = abuf;
-	return (0);
-}
-
-int
-dmu_xuio_cnt(xuio_t *xuio)
-{
-	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
-	return (priv->cnt);
-}
-
-arc_buf_t *
-dmu_xuio_arcbuf(xuio_t *xuio, int i)
-{
-	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
-
-	ASSERT(i < priv->cnt);
-	return (priv->bufs[i]);
-}
-
-void
-dmu_xuio_clear(xuio_t *xuio, int i)
-{
-	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
-
-	ASSERT(i < priv->cnt);
-	priv->bufs[i] = NULL;
-}
-#endif /* HAVE_UIO_ZEROCOPY */
-
-static void
-xuio_stat_init(void)
-{
-	xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
-	    KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
-	    KSTAT_FLAG_VIRTUAL);
-	if (xuio_ksp != NULL) {
-		xuio_ksp->ks_data = &xuio_stats;
-		kstat_install(xuio_ksp);
-	}
-}
-
-static void
-xuio_stat_fini(void)
-{
-	if (xuio_ksp != NULL) {
-		kstat_delete(xuio_ksp);
-		xuio_ksp = NULL;
-	}
-}
-
-void
-xuio_stat_wbuf_copied(void)
-{
-	XUIOSTAT_BUMP(xuiostat_wbuf_copied);
-}
-
-void
-xuio_stat_wbuf_nocopy(void)
-{
-	XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
-}
-
 #ifdef _KERNEL
 int
 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
@@ -1348,21 +1195,6 @@ dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
 		bufoff = uio_offset(uio) - 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;
-			arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
-			err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
-			if (!err)
-				uio_advance(uio, tocpy);
-
-			if (abuf == dbuf_abuf)
-				XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
-			else
-				XUIOSTAT_BUMP(xuiostat_rbuf_copied);
-		} else
-#endif
 #ifdef __FreeBSD__
 			err = vn_io_fault_uiomove((char *)db->db_data + bufoff,
 			    tocpy, uio);
@@ -1602,7 +1434,6 @@ dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset, arc_buf_t *buf,
 		dbuf_rele(db, FTAG);
 		dmu_write(os, object, offset, blksz, buf->b_data, tx);
 		dmu_return_arcbuf(buf);
-		XUIOSTAT_BUMP(xuiostat_wbuf_copied);
 	}
 
 	return (0);
@@ -2414,7 +2245,6 @@ dmu_init(void)
 	abd_init();
 	zfs_dbgmsg_init();
 	sa_cache_init();
-	xuio_stat_init();
 	dmu_objset_init();
 	dnode_init();
 	zfetch_init();
@@ -2434,7 +2264,6 @@ dmu_fini(void)
 	dbuf_fini();
 	dnode_fini();
 	dmu_objset_fini();
-	xuio_stat_fini();
 	sa_cache_fini();
 	zfs_dbgmsg_fini();
 	abd_fini();