MFC r272601: MFV r272591:

Use loaned ARC buffer for zfs receive to avoid copy.

Illumos issue:
    5162 zfs recv should use loaned arc buffer to avoid copy

2 files changed, 37 insertions, 18 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
index a00717b..8b04fdd 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
@@ -1333,7 +1333,14 @@ dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
 	rw_exit(&dn->dn_struct_rwlock);
 	DB_DNODE_EXIT(dbuf);
 
-	if (offset == db->db.db_offset && blksz == db->db.db_size) {
+	/*
+	 * We can only assign if the offset is aligned, the arc buf is the
+	 * same size as the dbuf, and the dbuf is not metadata.  It
+	 * can't be metadata because the loaned arc buf comes from the
+	 * user-data kmem arena.
+	 */
+	if (offset == db->db.db_offset && blksz == db->db.db_size &&
+	    DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA) {
 		dbuf_assign_arcbuf(db, buf, tx);
 		dbuf_rele(db, FTAG);
 	} else {
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
index 7c5b5f3..314e73c 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
@@ -1273,18 +1273,20 @@ restore_bytes(struct restorearg *ra, void *buf, int len, off_t off, ssize_t *res
 }
 
 static void *
-restore_read(struct restorearg *ra, int len)
+restore_read(struct restorearg *ra, int len, char *buf)
 {
-	void *rv;
 	int done = 0;
 
+	if (buf == NULL)
+		buf = ra->buf;
+
 	/* some things will require 8-byte alignment, so everything must */
 	ASSERT0(len % 8);
 
 	while (done < len) {
 		ssize_t resid;
 
-		ra->err = restore_bytes(ra, (caddr_t)ra->buf + done,
+		ra->err = restore_bytes(ra, buf + done,
 		    len - done, ra->voff, &resid);
 
 		if (resid == len - done)
@@ -1296,12 +1298,11 @@ restore_read(struct restorearg *ra, int len)
 	}
 
 	ASSERT3U(done, ==, len);
-	rv = ra->buf;
 	if (ra->byteswap)
-		fletcher_4_incremental_byteswap(rv, len, &ra->cksum);
+		fletcher_4_incremental_byteswap(buf, len, &ra->cksum);
 	else
-		fletcher_4_incremental_native(rv, len, &ra->cksum);
-	return (rv);
+		fletcher_4_incremental_native(buf, len, &ra->cksum);
+	return (buf);
 }
 
 static void
@@ -1416,7 +1417,7 @@ restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
 		return (SET_ERROR(EINVAL));
 
 	if (drro->drr_bonuslen) {
-		data = restore_read(ra, P2ROUNDUP(drro->drr_bonuslen, 8));
+		data = restore_read(ra, P2ROUNDUP(drro->drr_bonuslen, 8), NULL);
 		if (ra->err != 0)
 			return (ra->err);
 	}
@@ -1513,19 +1514,30 @@ restore_write(struct restorearg *ra, objset_t *os,
 	    !DMU_OT_IS_VALID(drrw->drr_type))
 		return (SET_ERROR(EINVAL));
 
-	data = restore_read(ra, drrw->drr_length);
-	if (data == NULL)
-		return (ra->err);
-
 	if (dmu_object_info(os, drrw->drr_object, NULL) != 0)
 		return (SET_ERROR(EINVAL));
 
+	dmu_buf_t *bonus;
+	if (dmu_bonus_hold(os, drrw->drr_object, FTAG, &bonus) != 0)
+		return (SET_ERROR(EINVAL));
+
+	arc_buf_t *abuf = dmu_request_arcbuf(bonus, drrw->drr_length);
+
+	data = restore_read(ra, drrw->drr_length, abuf->b_data);
+	if (data == NULL) {
+		dmu_return_arcbuf(abuf);
+		dmu_buf_rele(bonus, FTAG);
+		return (ra->err);
+	}
+
 	tx = dmu_tx_create(os);
 
 	dmu_tx_hold_write(tx, drrw->drr_object,
 	    drrw->drr_offset, drrw->drr_length);
 	err = dmu_tx_assign(tx, TXG_WAIT);
 	if (err != 0) {
+		dmu_return_arcbuf(abuf);
+		dmu_buf_rele(bonus, FTAG);
 		dmu_tx_abort(tx);
 		return (err);
 	}
@@ -1534,9 +1546,9 @@ restore_write(struct restorearg *ra, objset_t *os,
 		    DMU_OT_BYTESWAP(drrw->drr_type);
 		dmu_ot_byteswap[byteswap].ob_func(data, drrw->drr_length);
 	}
-	dmu_write(os, drrw->drr_object,
-	    drrw->drr_offset, drrw->drr_length, data, tx);
+	dmu_assign_arcbuf(bonus, drrw->drr_offset, abuf, tx);
 	dmu_tx_commit(tx);
+	dmu_buf_rele(bonus, FTAG);
 	return (0);
 }
 
@@ -1618,7 +1630,7 @@ restore_write_embedded(struct restorearg *ra, objset_t *os,
 	if (drrwnp->drr_compression >= ZIO_COMPRESS_FUNCTIONS)
 		return (EINVAL);
 
-	data = restore_read(ra, P2ROUNDUP(drrwnp->drr_psize, 8));
+	data = restore_read(ra, P2ROUNDUP(drrwnp->drr_psize, 8), NULL);
 	if (data == NULL)
 		return (ra->err);
 
@@ -1653,7 +1665,7 @@ restore_spill(struct restorearg *ra, objset_t *os, struct drr_spill *drrs)
 	    drrs->drr_length > SPA_MAXBLOCKSIZE)
 		return (SET_ERROR(EINVAL));
 
-	data = restore_read(ra, drrs->drr_length);
+	data = restore_read(ra, drrs->drr_length, NULL);
 	if (data == NULL)
 		return (ra->err);
 
@@ -1795,7 +1807,7 @@ dmu_recv_stream(dmu_recv_cookie_t *drc, struct file *fp, offset_t *voffp,
 	 */
 	pcksum = ra.cksum;
 	while (ra.err == 0 &&
-	    NULL != (drr = restore_read(&ra, sizeof (*drr)))) {
+	    NULL != (drr = restore_read(&ra, sizeof (*drr), NULL))) {
 		if (issig(JUSTLOOKING) && issig(FORREAL)) {
 			ra.err = SET_ERROR(EINTR);
 			goto out;