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

5162 zfs recv should use loaned arc buffer to avoid copy
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Bayard Bell <Bayard.Bell@nexenta.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/5162
  https://github.com/illumos/illumos-gate/commit/8a90470

Porting notes:
  Fix spelling error 's/arena/area/' in dmu.c.
  In restore_write() declare bonus and abuf at the top of the function.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2696

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 81432b9bad94c4fbdbd61e6c5ff992438cad7738..98defa3bbfd6172ec42bfbd2a9c63b892846bbf8 100644 (file)
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -1387,7 +1387,14 @@ 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 area.
+        */
+       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/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
index feb089fd59e84a829f7318350a0588b92ac92fc4..1f61368c5d651bfac27efd98c4e7353530478194 100644 (file)
--- a/module/zfs/dmu_send.c
+++ b/module/zfs/dmu_send.c
@@ -1206,11 +1206,13 @@ free_guid_map_onexit(void *arg)
 }
 
 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);
 
@@ -1218,7 +1220,7 @@ restore_read(struct restorearg *ra, int len)
                ssize_t resid;
 
                ra->err = vn_rdwr(UIO_READ, ra->vp,
-                   (caddr_t)ra->buf + done, len - done,
+                   buf + done, len - done,
                    ra->voff, UIO_SYSSPACE, FAPPEND,
                    RLIM64_INFINITY, CRED(), &resid);
 
@@ -1231,12 +1233,11 @@ 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);
 }
 
 noinline static void
@@ -1367,7 +1368,7 @@ restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
        object = err == 0 ? drro->drr_object : DMU_NEW_OBJECT;
 
        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);
        }
@@ -1473,6 +1474,8 @@ restore_write(struct restorearg *ra, objset_t *os,
     struct drr_write *drrw)
 {
        dmu_tx_t *tx;
+       dmu_buf_t *bonus;
+       arc_buf_t *abuf;
        void *data;
        int err;
 
@@ -1480,19 +1483,29 @@ 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));
 
+       if (dmu_bonus_hold(os, drrw->drr_object, FTAG, &bonus) != 0)
+               return (SET_ERROR(EINVAL));
+
+       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);
        }
@@ -1501,9 +1514,9 @@ 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);
 }
 
@@ -1585,7 +1598,7 @@ 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);
 
@@ -1620,7 +1633,7 @@ 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);
 
@@ -1761,7 +1774,7 @@ dmu_recv_stream(dmu_recv_cookie_t *drc, vnode_t *vp, 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;