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-rw-r--r--uts/common/fs/zfs/dmu_tx.c1382
1 files changed, 1382 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/dmu_tx.c b/uts/common/fs/zfs/dmu_tx.c
new file mode 100644
index 000000000000..bd5c71a2265e
--- /dev/null
+++ b/uts/common/fs/zfs/dmu_tx.c
@@ -0,0 +1,1382 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+#include <sys/dmu.h>
+#include <sys/dmu_impl.h>
+#include <sys/dbuf.h>
+#include <sys/dmu_tx.h>
+#include <sys/dmu_objset.h>
+#include <sys/dsl_dataset.h> /* for dsl_dataset_block_freeable() */
+#include <sys/dsl_dir.h> /* for dsl_dir_tempreserve_*() */
+#include <sys/dsl_pool.h>
+#include <sys/zap_impl.h> /* for fzap_default_block_shift */
+#include <sys/spa.h>
+#include <sys/sa.h>
+#include <sys/sa_impl.h>
+#include <sys/zfs_context.h>
+#include <sys/varargs.h>
+
+typedef void (*dmu_tx_hold_func_t)(dmu_tx_t *tx, struct dnode *dn,
+ uint64_t arg1, uint64_t arg2);
+
+
+dmu_tx_t *
+dmu_tx_create_dd(dsl_dir_t *dd)
+{
+ dmu_tx_t *tx = kmem_zalloc(sizeof (dmu_tx_t), KM_SLEEP);
+ tx->tx_dir = dd;
+ if (dd)
+ tx->tx_pool = dd->dd_pool;
+ list_create(&tx->tx_holds, sizeof (dmu_tx_hold_t),
+ offsetof(dmu_tx_hold_t, txh_node));
+ list_create(&tx->tx_callbacks, sizeof (dmu_tx_callback_t),
+ offsetof(dmu_tx_callback_t, dcb_node));
+#ifdef ZFS_DEBUG
+ refcount_create(&tx->tx_space_written);
+ refcount_create(&tx->tx_space_freed);
+#endif
+ return (tx);
+}
+
+dmu_tx_t *
+dmu_tx_create(objset_t *os)
+{
+ dmu_tx_t *tx = dmu_tx_create_dd(os->os_dsl_dataset->ds_dir);
+ tx->tx_objset = os;
+ tx->tx_lastsnap_txg = dsl_dataset_prev_snap_txg(os->os_dsl_dataset);
+ return (tx);
+}
+
+dmu_tx_t *
+dmu_tx_create_assigned(struct dsl_pool *dp, uint64_t txg)
+{
+ dmu_tx_t *tx = dmu_tx_create_dd(NULL);
+
+ ASSERT3U(txg, <=, dp->dp_tx.tx_open_txg);
+ tx->tx_pool = dp;
+ tx->tx_txg = txg;
+ tx->tx_anyobj = TRUE;
+
+ return (tx);
+}
+
+int
+dmu_tx_is_syncing(dmu_tx_t *tx)
+{
+ return (tx->tx_anyobj);
+}
+
+int
+dmu_tx_private_ok(dmu_tx_t *tx)
+{
+ return (tx->tx_anyobj);
+}
+
+static dmu_tx_hold_t *
+dmu_tx_hold_object_impl(dmu_tx_t *tx, objset_t *os, uint64_t object,
+ enum dmu_tx_hold_type type, uint64_t arg1, uint64_t arg2)
+{
+ dmu_tx_hold_t *txh;
+ dnode_t *dn = NULL;
+ int err;
+
+ if (object != DMU_NEW_OBJECT) {
+ err = dnode_hold(os, object, tx, &dn);
+ if (err) {
+ tx->tx_err = err;
+ return (NULL);
+ }
+
+ if (err == 0 && tx->tx_txg != 0) {
+ mutex_enter(&dn->dn_mtx);
+ /*
+ * dn->dn_assigned_txg == tx->tx_txg doesn't pose a
+ * problem, but there's no way for it to happen (for
+ * now, at least).
+ */
+ ASSERT(dn->dn_assigned_txg == 0);
+ dn->dn_assigned_txg = tx->tx_txg;
+ (void) refcount_add(&dn->dn_tx_holds, tx);
+ mutex_exit(&dn->dn_mtx);
+ }
+ }
+
+ txh = kmem_zalloc(sizeof (dmu_tx_hold_t), KM_SLEEP);
+ txh->txh_tx = tx;
+ txh->txh_dnode = dn;
+#ifdef ZFS_DEBUG
+ txh->txh_type = type;
+ txh->txh_arg1 = arg1;
+ txh->txh_arg2 = arg2;
+#endif
+ list_insert_tail(&tx->tx_holds, txh);
+
+ return (txh);
+}
+
+void
+dmu_tx_add_new_object(dmu_tx_t *tx, objset_t *os, uint64_t object)
+{
+ /*
+ * If we're syncing, they can manipulate any object anyhow, and
+ * the hold on the dnode_t can cause problems.
+ */
+ if (!dmu_tx_is_syncing(tx)) {
+ (void) dmu_tx_hold_object_impl(tx, os,
+ object, THT_NEWOBJECT, 0, 0);
+ }
+}
+
+static int
+dmu_tx_check_ioerr(zio_t *zio, dnode_t *dn, int level, uint64_t blkid)
+{
+ int err;
+ dmu_buf_impl_t *db;
+
+ rw_enter(&dn->dn_struct_rwlock, RW_READER);
+ db = dbuf_hold_level(dn, level, blkid, FTAG);
+ rw_exit(&dn->dn_struct_rwlock);
+ if (db == NULL)
+ return (EIO);
+ err = dbuf_read(db, zio, DB_RF_CANFAIL | DB_RF_NOPREFETCH);
+ dbuf_rele(db, FTAG);
+ return (err);
+}
+
+static void
+dmu_tx_count_twig(dmu_tx_hold_t *txh, dnode_t *dn, dmu_buf_impl_t *db,
+ int level, uint64_t blkid, boolean_t freeable, uint64_t *history)
+{
+ objset_t *os = dn->dn_objset;
+ dsl_dataset_t *ds = os->os_dsl_dataset;
+ int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
+ dmu_buf_impl_t *parent = NULL;
+ blkptr_t *bp = NULL;
+ uint64_t space;
+
+ if (level >= dn->dn_nlevels || history[level] == blkid)
+ return;
+
+ history[level] = blkid;
+
+ space = (level == 0) ? dn->dn_datablksz : (1ULL << dn->dn_indblkshift);
+
+ if (db == NULL || db == dn->dn_dbuf) {
+ ASSERT(level != 0);
+ db = NULL;
+ } else {
+ ASSERT(DB_DNODE(db) == dn);
+ ASSERT(db->db_level == level);
+ ASSERT(db->db.db_size == space);
+ ASSERT(db->db_blkid == blkid);
+ bp = db->db_blkptr;
+ parent = db->db_parent;
+ }
+
+ freeable = (bp && (freeable ||
+ dsl_dataset_block_freeable(ds, bp, bp->blk_birth)));
+
+ if (freeable)
+ txh->txh_space_tooverwrite += space;
+ else
+ txh->txh_space_towrite += space;
+ if (bp)
+ txh->txh_space_tounref += bp_get_dsize(os->os_spa, bp);
+
+ dmu_tx_count_twig(txh, dn, parent, level + 1,
+ blkid >> epbs, freeable, history);
+}
+
+/* ARGSUSED */
+static void
+dmu_tx_count_write(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
+{
+ dnode_t *dn = txh->txh_dnode;
+ uint64_t start, end, i;
+ int min_bs, max_bs, min_ibs, max_ibs, epbs, bits;
+ int err = 0;
+
+ if (len == 0)
+ return;
+
+ min_bs = SPA_MINBLOCKSHIFT;
+ max_bs = SPA_MAXBLOCKSHIFT;
+ min_ibs = DN_MIN_INDBLKSHIFT;
+ max_ibs = DN_MAX_INDBLKSHIFT;
+
+ if (dn) {
+ uint64_t history[DN_MAX_LEVELS];
+ int nlvls = dn->dn_nlevels;
+ int delta;
+
+ /*
+ * For i/o error checking, read the first and last level-0
+ * blocks (if they are not aligned), and all the level-1 blocks.
+ */
+ if (dn->dn_maxblkid == 0) {
+ delta = dn->dn_datablksz;
+ start = (off < dn->dn_datablksz) ? 0 : 1;
+ end = (off+len <= dn->dn_datablksz) ? 0 : 1;
+ if (start == 0 && (off > 0 || len < dn->dn_datablksz)) {
+ err = dmu_tx_check_ioerr(NULL, dn, 0, 0);
+ if (err)
+ goto out;
+ delta -= off;
+ }
+ } else {
+ zio_t *zio = zio_root(dn->dn_objset->os_spa,
+ NULL, NULL, ZIO_FLAG_CANFAIL);
+
+ /* first level-0 block */
+ start = off >> dn->dn_datablkshift;
+ if (P2PHASE(off, dn->dn_datablksz) ||
+ len < dn->dn_datablksz) {
+ err = dmu_tx_check_ioerr(zio, dn, 0, start);
+ if (err)
+ goto out;
+ }
+
+ /* last level-0 block */
+ end = (off+len-1) >> dn->dn_datablkshift;
+ if (end != start && end <= dn->dn_maxblkid &&
+ P2PHASE(off+len, dn->dn_datablksz)) {
+ err = dmu_tx_check_ioerr(zio, dn, 0, end);
+ if (err)
+ goto out;
+ }
+
+ /* level-1 blocks */
+ if (nlvls > 1) {
+ int shft = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
+ for (i = (start>>shft)+1; i < end>>shft; i++) {
+ err = dmu_tx_check_ioerr(zio, dn, 1, i);
+ if (err)
+ goto out;
+ }
+ }
+
+ err = zio_wait(zio);
+ if (err)
+ goto out;
+ delta = P2NPHASE(off, dn->dn_datablksz);
+ }
+
+ if (dn->dn_maxblkid > 0) {
+ /*
+ * The blocksize can't change,
+ * so we can make a more precise estimate.
+ */
+ ASSERT(dn->dn_datablkshift != 0);
+ min_bs = max_bs = dn->dn_datablkshift;
+ min_ibs = max_ibs = dn->dn_indblkshift;
+ } else if (dn->dn_indblkshift > max_ibs) {
+ /*
+ * This ensures that if we reduce DN_MAX_INDBLKSHIFT,
+ * the code will still work correctly on older pools.
+ */
+ min_ibs = max_ibs = dn->dn_indblkshift;
+ }
+
+ /*
+ * If this write is not off the end of the file
+ * we need to account for overwrites/unref.
+ */
+ if (start <= dn->dn_maxblkid) {
+ for (int l = 0; l < DN_MAX_LEVELS; l++)
+ history[l] = -1ULL;
+ }
+ while (start <= dn->dn_maxblkid) {
+ dmu_buf_impl_t *db;
+
+ rw_enter(&dn->dn_struct_rwlock, RW_READER);
+ err = dbuf_hold_impl(dn, 0, start, FALSE, FTAG, &db);
+ rw_exit(&dn->dn_struct_rwlock);
+
+ if (err) {
+ txh->txh_tx->tx_err = err;
+ return;
+ }
+
+ dmu_tx_count_twig(txh, dn, db, 0, start, B_FALSE,
+ history);
+ dbuf_rele(db, FTAG);
+ if (++start > end) {
+ /*
+ * Account for new indirects appearing
+ * before this IO gets assigned into a txg.
+ */
+ bits = 64 - min_bs;
+ epbs = min_ibs - SPA_BLKPTRSHIFT;
+ for (bits -= epbs * (nlvls - 1);
+ bits >= 0; bits -= epbs)
+ txh->txh_fudge += 1ULL << max_ibs;
+ goto out;
+ }
+ off += delta;
+ if (len >= delta)
+ len -= delta;
+ delta = dn->dn_datablksz;
+ }
+ }
+
+ /*
+ * 'end' is the last thing we will access, not one past.
+ * This way we won't overflow when accessing the last byte.
+ */
+ start = P2ALIGN(off, 1ULL << max_bs);
+ end = P2ROUNDUP(off + len, 1ULL << max_bs) - 1;
+ txh->txh_space_towrite += end - start + 1;
+
+ start >>= min_bs;
+ end >>= min_bs;
+
+ epbs = min_ibs - SPA_BLKPTRSHIFT;
+
+ /*
+ * The object contains at most 2^(64 - min_bs) blocks,
+ * and each indirect level maps 2^epbs.
+ */
+ for (bits = 64 - min_bs; bits >= 0; bits -= epbs) {
+ start >>= epbs;
+ end >>= epbs;
+ ASSERT3U(end, >=, start);
+ txh->txh_space_towrite += (end - start + 1) << max_ibs;
+ if (start != 0) {
+ /*
+ * We also need a new blkid=0 indirect block
+ * to reference any existing file data.
+ */
+ txh->txh_space_towrite += 1ULL << max_ibs;
+ }
+ }
+
+out:
+ if (txh->txh_space_towrite + txh->txh_space_tooverwrite >
+ 2 * DMU_MAX_ACCESS)
+ err = EFBIG;
+
+ if (err)
+ txh->txh_tx->tx_err = err;
+}
+
+static void
+dmu_tx_count_dnode(dmu_tx_hold_t *txh)
+{
+ dnode_t *dn = txh->txh_dnode;
+ dnode_t *mdn = DMU_META_DNODE(txh->txh_tx->tx_objset);
+ uint64_t space = mdn->dn_datablksz +
+ ((mdn->dn_nlevels-1) << mdn->dn_indblkshift);
+
+ if (dn && dn->dn_dbuf->db_blkptr &&
+ dsl_dataset_block_freeable(dn->dn_objset->os_dsl_dataset,
+ dn->dn_dbuf->db_blkptr, dn->dn_dbuf->db_blkptr->blk_birth)) {
+ txh->txh_space_tooverwrite += space;
+ txh->txh_space_tounref += space;
+ } else {
+ txh->txh_space_towrite += space;
+ if (dn && dn->dn_dbuf->db_blkptr)
+ txh->txh_space_tounref += space;
+ }
+}
+
+void
+dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len)
+{
+ dmu_tx_hold_t *txh;
+
+ ASSERT(tx->tx_txg == 0);
+ ASSERT(len < DMU_MAX_ACCESS);
+ ASSERT(len == 0 || UINT64_MAX - off >= len - 1);
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
+ object, THT_WRITE, off, len);
+ if (txh == NULL)
+ return;
+
+ dmu_tx_count_write(txh, off, len);
+ dmu_tx_count_dnode(txh);
+}
+
+static void
+dmu_tx_count_free(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
+{
+ uint64_t blkid, nblks, lastblk;
+ uint64_t space = 0, unref = 0, skipped = 0;
+ dnode_t *dn = txh->txh_dnode;
+ dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
+ spa_t *spa = txh->txh_tx->tx_pool->dp_spa;
+ int epbs;
+
+ if (dn->dn_nlevels == 0)
+ return;
+
+ /*
+ * The struct_rwlock protects us against dn_nlevels
+ * changing, in case (against all odds) we manage to dirty &
+ * sync out the changes after we check for being dirty.
+ * Also, dbuf_hold_impl() wants us to have the struct_rwlock.
+ */
+ rw_enter(&dn->dn_struct_rwlock, RW_READER);
+ epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
+ if (dn->dn_maxblkid == 0) {
+ if (off == 0 && len >= dn->dn_datablksz) {
+ blkid = 0;
+ nblks = 1;
+ } else {
+ rw_exit(&dn->dn_struct_rwlock);
+ return;
+ }
+ } else {
+ blkid = off >> dn->dn_datablkshift;
+ nblks = (len + dn->dn_datablksz - 1) >> dn->dn_datablkshift;
+
+ if (blkid >= dn->dn_maxblkid) {
+ rw_exit(&dn->dn_struct_rwlock);
+ return;
+ }
+ if (blkid + nblks > dn->dn_maxblkid)
+ nblks = dn->dn_maxblkid - blkid;
+
+ }
+ if (dn->dn_nlevels == 1) {
+ int i;
+ for (i = 0; i < nblks; i++) {
+ blkptr_t *bp = dn->dn_phys->dn_blkptr;
+ ASSERT3U(blkid + i, <, dn->dn_nblkptr);
+ bp += blkid + i;
+ if (dsl_dataset_block_freeable(ds, bp, bp->blk_birth)) {
+ dprintf_bp(bp, "can free old%s", "");
+ space += bp_get_dsize(spa, bp);
+ }
+ unref += BP_GET_ASIZE(bp);
+ }
+ nblks = 0;
+ }
+
+ /*
+ * Add in memory requirements of higher-level indirects.
+ * This assumes a worst-possible scenario for dn_nlevels.
+ */
+ {
+ uint64_t blkcnt = 1 + ((nblks >> epbs) >> epbs);
+ int level = (dn->dn_nlevels > 1) ? 2 : 1;
+
+ while (level++ < DN_MAX_LEVELS) {
+ txh->txh_memory_tohold += blkcnt << dn->dn_indblkshift;
+ blkcnt = 1 + (blkcnt >> epbs);
+ }
+ ASSERT(blkcnt <= dn->dn_nblkptr);
+ }
+
+ lastblk = blkid + nblks - 1;
+ while (nblks) {
+ dmu_buf_impl_t *dbuf;
+ uint64_t ibyte, new_blkid;
+ int epb = 1 << epbs;
+ int err, i, blkoff, tochk;
+ blkptr_t *bp;
+
+ ibyte = blkid << dn->dn_datablkshift;
+ err = dnode_next_offset(dn,
+ DNODE_FIND_HAVELOCK, &ibyte, 2, 1, 0);
+ new_blkid = ibyte >> dn->dn_datablkshift;
+ if (err == ESRCH) {
+ skipped += (lastblk >> epbs) - (blkid >> epbs) + 1;
+ break;
+ }
+ if (err) {
+ txh->txh_tx->tx_err = err;
+ break;
+ }
+ if (new_blkid > lastblk) {
+ skipped += (lastblk >> epbs) - (blkid >> epbs) + 1;
+ break;
+ }
+
+ if (new_blkid > blkid) {
+ ASSERT((new_blkid >> epbs) > (blkid >> epbs));
+ skipped += (new_blkid >> epbs) - (blkid >> epbs) - 1;
+ nblks -= new_blkid - blkid;
+ blkid = new_blkid;
+ }
+ blkoff = P2PHASE(blkid, epb);
+ tochk = MIN(epb - blkoff, nblks);
+
+ err = dbuf_hold_impl(dn, 1, blkid >> epbs, FALSE, FTAG, &dbuf);
+ if (err) {
+ txh->txh_tx->tx_err = err;
+ break;
+ }
+
+ txh->txh_memory_tohold += dbuf->db.db_size;
+
+ /*
+ * We don't check memory_tohold against DMU_MAX_ACCESS because
+ * memory_tohold is an over-estimation (especially the >L1
+ * indirect blocks), so it could fail. Callers should have
+ * already verified that they will not be holding too much
+ * memory.
+ */
+
+ err = dbuf_read(dbuf, NULL, DB_RF_HAVESTRUCT | DB_RF_CANFAIL);
+ if (err != 0) {
+ txh->txh_tx->tx_err = err;
+ dbuf_rele(dbuf, FTAG);
+ break;
+ }
+
+ bp = dbuf->db.db_data;
+ bp += blkoff;
+
+ for (i = 0; i < tochk; i++) {
+ if (dsl_dataset_block_freeable(ds, &bp[i],
+ bp[i].blk_birth)) {
+ dprintf_bp(&bp[i], "can free old%s", "");
+ space += bp_get_dsize(spa, &bp[i]);
+ }
+ unref += BP_GET_ASIZE(bp);
+ }
+ dbuf_rele(dbuf, FTAG);
+
+ blkid += tochk;
+ nblks -= tochk;
+ }
+ rw_exit(&dn->dn_struct_rwlock);
+
+ /* account for new level 1 indirect blocks that might show up */
+ if (skipped > 0) {
+ txh->txh_fudge += skipped << dn->dn_indblkshift;
+ skipped = MIN(skipped, DMU_MAX_DELETEBLKCNT >> epbs);
+ txh->txh_memory_tohold += skipped << dn->dn_indblkshift;
+ }
+ txh->txh_space_tofree += space;
+ txh->txh_space_tounref += unref;
+}
+
+void
+dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off, uint64_t len)
+{
+ dmu_tx_hold_t *txh;
+ dnode_t *dn;
+ uint64_t start, end, i;
+ int err, shift;
+ zio_t *zio;
+
+ ASSERT(tx->tx_txg == 0);
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
+ object, THT_FREE, off, len);
+ if (txh == NULL)
+ return;
+ dn = txh->txh_dnode;
+
+ /* first block */
+ if (off != 0)
+ dmu_tx_count_write(txh, off, 1);
+ /* last block */
+ if (len != DMU_OBJECT_END)
+ dmu_tx_count_write(txh, off+len, 1);
+
+ dmu_tx_count_dnode(txh);
+
+ if (off >= (dn->dn_maxblkid+1) * dn->dn_datablksz)
+ return;
+ if (len == DMU_OBJECT_END)
+ len = (dn->dn_maxblkid+1) * dn->dn_datablksz - off;
+
+ /*
+ * For i/o error checking, read the first and last level-0
+ * blocks, and all the level-1 blocks. The above count_write's
+ * have already taken care of the level-0 blocks.
+ */
+ if (dn->dn_nlevels > 1) {
+ shift = dn->dn_datablkshift + dn->dn_indblkshift -
+ SPA_BLKPTRSHIFT;
+ start = off >> shift;
+ end = dn->dn_datablkshift ? ((off+len) >> shift) : 0;
+
+ zio = zio_root(tx->tx_pool->dp_spa,
+ NULL, NULL, ZIO_FLAG_CANFAIL);
+ for (i = start; i <= end; i++) {
+ uint64_t ibyte = i << shift;
+ err = dnode_next_offset(dn, 0, &ibyte, 2, 1, 0);
+ i = ibyte >> shift;
+ if (err == ESRCH)
+ break;
+ if (err) {
+ tx->tx_err = err;
+ return;
+ }
+
+ err = dmu_tx_check_ioerr(zio, dn, 1, i);
+ if (err) {
+ tx->tx_err = err;
+ return;
+ }
+ }
+ err = zio_wait(zio);
+ if (err) {
+ tx->tx_err = err;
+ return;
+ }
+ }
+
+ dmu_tx_count_free(txh, off, len);
+}
+
+void
+dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name)
+{
+ dmu_tx_hold_t *txh;
+ dnode_t *dn;
+ uint64_t nblocks;
+ int epbs, err;
+
+ ASSERT(tx->tx_txg == 0);
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
+ object, THT_ZAP, add, (uintptr_t)name);
+ if (txh == NULL)
+ return;
+ dn = txh->txh_dnode;
+
+ dmu_tx_count_dnode(txh);
+
+ if (dn == NULL) {
+ /*
+ * We will be able to fit a new object's entries into one leaf
+ * block. So there will be at most 2 blocks total,
+ * including the header block.
+ */
+ dmu_tx_count_write(txh, 0, 2 << fzap_default_block_shift);
+ return;
+ }
+
+ ASSERT3P(dmu_ot[dn->dn_type].ot_byteswap, ==, zap_byteswap);
+
+ if (dn->dn_maxblkid == 0 && !add) {
+ /*
+ * If there is only one block (i.e. this is a micro-zap)
+ * and we are not adding anything, the accounting is simple.
+ */
+ err = dmu_tx_check_ioerr(NULL, dn, 0, 0);
+ if (err) {
+ tx->tx_err = err;
+ return;
+ }
+
+ /*
+ * Use max block size here, since we don't know how much
+ * the size will change between now and the dbuf dirty call.
+ */
+ if (dsl_dataset_block_freeable(dn->dn_objset->os_dsl_dataset,
+ &dn->dn_phys->dn_blkptr[0],
+ dn->dn_phys->dn_blkptr[0].blk_birth)) {
+ txh->txh_space_tooverwrite += SPA_MAXBLOCKSIZE;
+ } else {
+ txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+ }
+ if (dn->dn_phys->dn_blkptr[0].blk_birth)
+ txh->txh_space_tounref += SPA_MAXBLOCKSIZE;
+ return;
+ }
+
+ if (dn->dn_maxblkid > 0 && name) {
+ /*
+ * access the name in this fat-zap so that we'll check
+ * for i/o errors to the leaf blocks, etc.
+ */
+ err = zap_lookup(dn->dn_objset, dn->dn_object, name,
+ 8, 0, NULL);
+ if (err == EIO) {
+ tx->tx_err = err;
+ return;
+ }
+ }
+
+ err = zap_count_write(dn->dn_objset, dn->dn_object, name, add,
+ &txh->txh_space_towrite, &txh->txh_space_tooverwrite);
+
+ /*
+ * If the modified blocks are scattered to the four winds,
+ * we'll have to modify an indirect twig for each.
+ */
+ epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
+ for (nblocks = dn->dn_maxblkid >> epbs; nblocks != 0; nblocks >>= epbs)
+ if (dn->dn_objset->os_dsl_dataset->ds_phys->ds_prev_snap_obj)
+ txh->txh_space_towrite += 3 << dn->dn_indblkshift;
+ else
+ txh->txh_space_tooverwrite += 3 << dn->dn_indblkshift;
+}
+
+void
+dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object)
+{
+ dmu_tx_hold_t *txh;
+
+ ASSERT(tx->tx_txg == 0);
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
+ object, THT_BONUS, 0, 0);
+ if (txh)
+ dmu_tx_count_dnode(txh);
+}
+
+void
+dmu_tx_hold_space(dmu_tx_t *tx, uint64_t space)
+{
+ dmu_tx_hold_t *txh;
+ ASSERT(tx->tx_txg == 0);
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
+ DMU_NEW_OBJECT, THT_SPACE, space, 0);
+
+ txh->txh_space_towrite += space;
+}
+
+int
+dmu_tx_holds(dmu_tx_t *tx, uint64_t object)
+{
+ dmu_tx_hold_t *txh;
+ int holds = 0;
+
+ /*
+ * By asserting that the tx is assigned, we're counting the
+ * number of dn_tx_holds, which is the same as the number of
+ * dn_holds. Otherwise, we'd be counting dn_holds, but
+ * dn_tx_holds could be 0.
+ */
+ ASSERT(tx->tx_txg != 0);
+
+ /* if (tx->tx_anyobj == TRUE) */
+ /* return (0); */
+
+ for (txh = list_head(&tx->tx_holds); txh;
+ txh = list_next(&tx->tx_holds, txh)) {
+ if (txh->txh_dnode && txh->txh_dnode->dn_object == object)
+ holds++;
+ }
+
+ return (holds);
+}
+
+#ifdef ZFS_DEBUG
+void
+dmu_tx_dirty_buf(dmu_tx_t *tx, dmu_buf_impl_t *db)
+{
+ dmu_tx_hold_t *txh;
+ int match_object = FALSE, match_offset = FALSE;
+ dnode_t *dn;
+
+ DB_DNODE_ENTER(db);
+ dn = DB_DNODE(db);
+ ASSERT(tx->tx_txg != 0);
+ ASSERT(tx->tx_objset == NULL || dn->dn_objset == tx->tx_objset);
+ ASSERT3U(dn->dn_object, ==, db->db.db_object);
+
+ if (tx->tx_anyobj) {
+ DB_DNODE_EXIT(db);
+ return;
+ }
+
+ /* XXX No checking on the meta dnode for now */
+ if (db->db.db_object == DMU_META_DNODE_OBJECT) {
+ DB_DNODE_EXIT(db);
+ return;
+ }
+
+ for (txh = list_head(&tx->tx_holds); txh;
+ txh = list_next(&tx->tx_holds, txh)) {
+ ASSERT(dn == NULL || dn->dn_assigned_txg == tx->tx_txg);
+ if (txh->txh_dnode == dn && txh->txh_type != THT_NEWOBJECT)
+ match_object = TRUE;
+ if (txh->txh_dnode == NULL || txh->txh_dnode == dn) {
+ int datablkshift = dn->dn_datablkshift ?
+ dn->dn_datablkshift : SPA_MAXBLOCKSHIFT;
+ int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
+ int shift = datablkshift + epbs * db->db_level;
+ uint64_t beginblk = shift >= 64 ? 0 :
+ (txh->txh_arg1 >> shift);
+ uint64_t endblk = shift >= 64 ? 0 :
+ ((txh->txh_arg1 + txh->txh_arg2 - 1) >> shift);
+ uint64_t blkid = db->db_blkid;
+
+ /* XXX txh_arg2 better not be zero... */
+
+ dprintf("found txh type %x beginblk=%llx endblk=%llx\n",
+ txh->txh_type, beginblk, endblk);
+
+ switch (txh->txh_type) {
+ case THT_WRITE:
+ if (blkid >= beginblk && blkid <= endblk)
+ match_offset = TRUE;
+ /*
+ * We will let this hold work for the bonus
+ * or spill buffer so that we don't need to
+ * hold it when creating a new object.
+ */
+ if (blkid == DMU_BONUS_BLKID ||
+ blkid == DMU_SPILL_BLKID)
+ match_offset = TRUE;
+ /*
+ * They might have to increase nlevels,
+ * thus dirtying the new TLIBs. Or the
+ * might have to change the block size,
+ * thus dirying the new lvl=0 blk=0.
+ */
+ if (blkid == 0)
+ match_offset = TRUE;
+ break;
+ case THT_FREE:
+ /*
+ * We will dirty all the level 1 blocks in
+ * the free range and perhaps the first and
+ * last level 0 block.
+ */
+ if (blkid >= beginblk && (blkid <= endblk ||
+ txh->txh_arg2 == DMU_OBJECT_END))
+ match_offset = TRUE;
+ break;
+ case THT_SPILL:
+ if (blkid == DMU_SPILL_BLKID)
+ match_offset = TRUE;
+ break;
+ case THT_BONUS:
+ if (blkid == DMU_BONUS_BLKID)
+ match_offset = TRUE;
+ break;
+ case THT_ZAP:
+ match_offset = TRUE;
+ break;
+ case THT_NEWOBJECT:
+ match_object = TRUE;
+ break;
+ default:
+ ASSERT(!"bad txh_type");
+ }
+ }
+ if (match_object && match_offset) {
+ DB_DNODE_EXIT(db);
+ return;
+ }
+ }
+ DB_DNODE_EXIT(db);
+ panic("dirtying dbuf obj=%llx lvl=%u blkid=%llx but not tx_held\n",
+ (u_longlong_t)db->db.db_object, db->db_level,
+ (u_longlong_t)db->db_blkid);
+}
+#endif
+
+static int
+dmu_tx_try_assign(dmu_tx_t *tx, uint64_t txg_how)
+{
+ dmu_tx_hold_t *txh;
+ spa_t *spa = tx->tx_pool->dp_spa;
+ uint64_t memory, asize, fsize, usize;
+ uint64_t towrite, tofree, tooverwrite, tounref, tohold, fudge;
+
+ ASSERT3U(tx->tx_txg, ==, 0);
+
+ if (tx->tx_err)
+ return (tx->tx_err);
+
+ if (spa_suspended(spa)) {
+ /*
+ * If the user has indicated a blocking failure mode
+ * then return ERESTART which will block in dmu_tx_wait().
+ * Otherwise, return EIO so that an error can get
+ * propagated back to the VOP calls.
+ *
+ * Note that we always honor the txg_how flag regardless
+ * of the failuremode setting.
+ */
+ if (spa_get_failmode(spa) == ZIO_FAILURE_MODE_CONTINUE &&
+ txg_how != TXG_WAIT)
+ return (EIO);
+
+ return (ERESTART);
+ }
+
+ tx->tx_txg = txg_hold_open(tx->tx_pool, &tx->tx_txgh);
+ tx->tx_needassign_txh = NULL;
+
+ /*
+ * NB: No error returns are allowed after txg_hold_open, but
+ * before processing the dnode holds, due to the
+ * dmu_tx_unassign() logic.
+ */
+
+ towrite = tofree = tooverwrite = tounref = tohold = fudge = 0;
+ for (txh = list_head(&tx->tx_holds); txh;
+ txh = list_next(&tx->tx_holds, txh)) {
+ dnode_t *dn = txh->txh_dnode;
+ if (dn != NULL) {
+ mutex_enter(&dn->dn_mtx);
+ if (dn->dn_assigned_txg == tx->tx_txg - 1) {
+ mutex_exit(&dn->dn_mtx);
+ tx->tx_needassign_txh = txh;
+ return (ERESTART);
+ }
+ if (dn->dn_assigned_txg == 0)
+ dn->dn_assigned_txg = tx->tx_txg;
+ ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
+ (void) refcount_add(&dn->dn_tx_holds, tx);
+ mutex_exit(&dn->dn_mtx);
+ }
+ towrite += txh->txh_space_towrite;
+ tofree += txh->txh_space_tofree;
+ tooverwrite += txh->txh_space_tooverwrite;
+ tounref += txh->txh_space_tounref;
+ tohold += txh->txh_memory_tohold;
+ fudge += txh->txh_fudge;
+ }
+
+ /*
+ * NB: This check must be after we've held the dnodes, so that
+ * the dmu_tx_unassign() logic will work properly
+ */
+ if (txg_how >= TXG_INITIAL && txg_how != tx->tx_txg)
+ return (ERESTART);
+
+ /*
+ * If a snapshot has been taken since we made our estimates,
+ * assume that we won't be able to free or overwrite anything.
+ */
+ if (tx->tx_objset &&
+ dsl_dataset_prev_snap_txg(tx->tx_objset->os_dsl_dataset) >
+ tx->tx_lastsnap_txg) {
+ towrite += tooverwrite;
+ tooverwrite = tofree = 0;
+ }
+
+ /* needed allocation: worst-case estimate of write space */
+ asize = spa_get_asize(tx->tx_pool->dp_spa, towrite + tooverwrite);
+ /* freed space estimate: worst-case overwrite + free estimate */
+ fsize = spa_get_asize(tx->tx_pool->dp_spa, tooverwrite) + tofree;
+ /* convert unrefd space to worst-case estimate */
+ usize = spa_get_asize(tx->tx_pool->dp_spa, tounref);
+ /* calculate memory footprint estimate */
+ memory = towrite + tooverwrite + tohold;
+
+#ifdef ZFS_DEBUG
+ /*
+ * Add in 'tohold' to account for our dirty holds on this memory
+ * XXX - the "fudge" factor is to account for skipped blocks that
+ * we missed because dnode_next_offset() misses in-core-only blocks.
+ */
+ tx->tx_space_towrite = asize +
+ spa_get_asize(tx->tx_pool->dp_spa, tohold + fudge);
+ tx->tx_space_tofree = tofree;
+ tx->tx_space_tooverwrite = tooverwrite;
+ tx->tx_space_tounref = tounref;
+#endif
+
+ if (tx->tx_dir && asize != 0) {
+ int err = dsl_dir_tempreserve_space(tx->tx_dir, memory,
+ asize, fsize, usize, &tx->tx_tempreserve_cookie, tx);
+ if (err)
+ return (err);
+ }
+
+ return (0);
+}
+
+static void
+dmu_tx_unassign(dmu_tx_t *tx)
+{
+ dmu_tx_hold_t *txh;
+
+ if (tx->tx_txg == 0)
+ return;
+
+ txg_rele_to_quiesce(&tx->tx_txgh);
+
+ for (txh = list_head(&tx->tx_holds); txh != tx->tx_needassign_txh;
+ txh = list_next(&tx->tx_holds, txh)) {
+ dnode_t *dn = txh->txh_dnode;
+
+ if (dn == NULL)
+ continue;
+ mutex_enter(&dn->dn_mtx);
+ ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
+
+ if (refcount_remove(&dn->dn_tx_holds, tx) == 0) {
+ dn->dn_assigned_txg = 0;
+ cv_broadcast(&dn->dn_notxholds);
+ }
+ mutex_exit(&dn->dn_mtx);
+ }
+
+ txg_rele_to_sync(&tx->tx_txgh);
+
+ tx->tx_lasttried_txg = tx->tx_txg;
+ tx->tx_txg = 0;
+}
+
+/*
+ * Assign tx to a transaction group. txg_how can be one of:
+ *
+ * (1) TXG_WAIT. If the current open txg is full, waits until there's
+ * a new one. This should be used when you're not holding locks.
+ * If will only fail if we're truly out of space (or over quota).
+ *
+ * (2) TXG_NOWAIT. If we can't assign into the current open txg without
+ * blocking, returns immediately with ERESTART. This should be used
+ * whenever you're holding locks. On an ERESTART error, the caller
+ * should drop locks, do a dmu_tx_wait(tx), and try again.
+ *
+ * (3) A specific txg. Use this if you need to ensure that multiple
+ * transactions all sync in the same txg. Like TXG_NOWAIT, it
+ * returns ERESTART if it can't assign you into the requested txg.
+ */
+int
+dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how)
+{
+ int err;
+
+ ASSERT(tx->tx_txg == 0);
+ ASSERT(txg_how != 0);
+ ASSERT(!dsl_pool_sync_context(tx->tx_pool));
+
+ while ((err = dmu_tx_try_assign(tx, txg_how)) != 0) {
+ dmu_tx_unassign(tx);
+
+ if (err != ERESTART || txg_how != TXG_WAIT)
+ return (err);
+
+ dmu_tx_wait(tx);
+ }
+
+ txg_rele_to_quiesce(&tx->tx_txgh);
+
+ return (0);
+}
+
+void
+dmu_tx_wait(dmu_tx_t *tx)
+{
+ spa_t *spa = tx->tx_pool->dp_spa;
+
+ ASSERT(tx->tx_txg == 0);
+
+ /*
+ * It's possible that the pool has become active after this thread
+ * has tried to obtain a tx. If that's the case then his
+ * tx_lasttried_txg would not have been assigned.
+ */
+ if (spa_suspended(spa) || tx->tx_lasttried_txg == 0) {
+ txg_wait_synced(tx->tx_pool, spa_last_synced_txg(spa) + 1);
+ } else if (tx->tx_needassign_txh) {
+ dnode_t *dn = tx->tx_needassign_txh->txh_dnode;
+
+ mutex_enter(&dn->dn_mtx);
+ while (dn->dn_assigned_txg == tx->tx_lasttried_txg - 1)
+ cv_wait(&dn->dn_notxholds, &dn->dn_mtx);
+ mutex_exit(&dn->dn_mtx);
+ tx->tx_needassign_txh = NULL;
+ } else {
+ txg_wait_open(tx->tx_pool, tx->tx_lasttried_txg + 1);
+ }
+}
+
+void
+dmu_tx_willuse_space(dmu_tx_t *tx, int64_t delta)
+{
+#ifdef ZFS_DEBUG
+ if (tx->tx_dir == NULL || delta == 0)
+ return;
+
+ if (delta > 0) {
+ ASSERT3U(refcount_count(&tx->tx_space_written) + delta, <=,
+ tx->tx_space_towrite);
+ (void) refcount_add_many(&tx->tx_space_written, delta, NULL);
+ } else {
+ (void) refcount_add_many(&tx->tx_space_freed, -delta, NULL);
+ }
+#endif
+}
+
+void
+dmu_tx_commit(dmu_tx_t *tx)
+{
+ dmu_tx_hold_t *txh;
+
+ ASSERT(tx->tx_txg != 0);
+
+ while (txh = list_head(&tx->tx_holds)) {
+ dnode_t *dn = txh->txh_dnode;
+
+ list_remove(&tx->tx_holds, txh);
+ kmem_free(txh, sizeof (dmu_tx_hold_t));
+ if (dn == NULL)
+ continue;
+ mutex_enter(&dn->dn_mtx);
+ ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
+
+ if (refcount_remove(&dn->dn_tx_holds, tx) == 0) {
+ dn->dn_assigned_txg = 0;
+ cv_broadcast(&dn->dn_notxholds);
+ }
+ mutex_exit(&dn->dn_mtx);
+ dnode_rele(dn, tx);
+ }
+
+ if (tx->tx_tempreserve_cookie)
+ dsl_dir_tempreserve_clear(tx->tx_tempreserve_cookie, tx);
+
+ if (!list_is_empty(&tx->tx_callbacks))
+ txg_register_callbacks(&tx->tx_txgh, &tx->tx_callbacks);
+
+ if (tx->tx_anyobj == FALSE)
+ txg_rele_to_sync(&tx->tx_txgh);
+
+ list_destroy(&tx->tx_callbacks);
+ list_destroy(&tx->tx_holds);
+#ifdef ZFS_DEBUG
+ dprintf("towrite=%llu written=%llu tofree=%llu freed=%llu\n",
+ tx->tx_space_towrite, refcount_count(&tx->tx_space_written),
+ tx->tx_space_tofree, refcount_count(&tx->tx_space_freed));
+ refcount_destroy_many(&tx->tx_space_written,
+ refcount_count(&tx->tx_space_written));
+ refcount_destroy_many(&tx->tx_space_freed,
+ refcount_count(&tx->tx_space_freed));
+#endif
+ kmem_free(tx, sizeof (dmu_tx_t));
+}
+
+void
+dmu_tx_abort(dmu_tx_t *tx)
+{
+ dmu_tx_hold_t *txh;
+
+ ASSERT(tx->tx_txg == 0);
+
+ while (txh = list_head(&tx->tx_holds)) {
+ dnode_t *dn = txh->txh_dnode;
+
+ list_remove(&tx->tx_holds, txh);
+ kmem_free(txh, sizeof (dmu_tx_hold_t));
+ if (dn != NULL)
+ dnode_rele(dn, tx);
+ }
+
+ /*
+ * Call any registered callbacks with an error code.
+ */
+ if (!list_is_empty(&tx->tx_callbacks))
+ dmu_tx_do_callbacks(&tx->tx_callbacks, ECANCELED);
+
+ list_destroy(&tx->tx_callbacks);
+ list_destroy(&tx->tx_holds);
+#ifdef ZFS_DEBUG
+ refcount_destroy_many(&tx->tx_space_written,
+ refcount_count(&tx->tx_space_written));
+ refcount_destroy_many(&tx->tx_space_freed,
+ refcount_count(&tx->tx_space_freed));
+#endif
+ kmem_free(tx, sizeof (dmu_tx_t));
+}
+
+uint64_t
+dmu_tx_get_txg(dmu_tx_t *tx)
+{
+ ASSERT(tx->tx_txg != 0);
+ return (tx->tx_txg);
+}
+
+void
+dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *func, void *data)
+{
+ dmu_tx_callback_t *dcb;
+
+ dcb = kmem_alloc(sizeof (dmu_tx_callback_t), KM_SLEEP);
+
+ dcb->dcb_func = func;
+ dcb->dcb_data = data;
+
+ list_insert_tail(&tx->tx_callbacks, dcb);
+}
+
+/*
+ * Call all the commit callbacks on a list, with a given error code.
+ */
+void
+dmu_tx_do_callbacks(list_t *cb_list, int error)
+{
+ dmu_tx_callback_t *dcb;
+
+ while (dcb = list_head(cb_list)) {
+ list_remove(cb_list, dcb);
+ dcb->dcb_func(dcb->dcb_data, error);
+ kmem_free(dcb, sizeof (dmu_tx_callback_t));
+ }
+}
+
+/*
+ * Interface to hold a bunch of attributes.
+ * used for creating new files.
+ * attrsize is the total size of all attributes
+ * to be added during object creation
+ *
+ * For updating/adding a single attribute dmu_tx_hold_sa() should be used.
+ */
+
+/*
+ * hold necessary attribute name for attribute registration.
+ * should be a very rare case where this is needed. If it does
+ * happen it would only happen on the first write to the file system.
+ */
+static void
+dmu_tx_sa_registration_hold(sa_os_t *sa, dmu_tx_t *tx)
+{
+ int i;
+
+ if (!sa->sa_need_attr_registration)
+ return;
+
+ for (i = 0; i != sa->sa_num_attrs; i++) {
+ if (!sa->sa_attr_table[i].sa_registered) {
+ if (sa->sa_reg_attr_obj)
+ dmu_tx_hold_zap(tx, sa->sa_reg_attr_obj,
+ B_TRUE, sa->sa_attr_table[i].sa_name);
+ else
+ dmu_tx_hold_zap(tx, DMU_NEW_OBJECT,
+ B_TRUE, sa->sa_attr_table[i].sa_name);
+ }
+ }
+}
+
+
+void
+dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object)
+{
+ dnode_t *dn;
+ dmu_tx_hold_t *txh;
+ blkptr_t *bp;
+
+ txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object,
+ THT_SPILL, 0, 0);
+
+ dn = txh->txh_dnode;
+
+ if (dn == NULL)
+ return;
+
+ /* If blkptr doesn't exist then add space to towrite */
+ bp = &dn->dn_phys->dn_spill;
+ if (BP_IS_HOLE(bp)) {
+ txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+ txh->txh_space_tounref = 0;
+ } else {
+ if (dsl_dataset_block_freeable(dn->dn_objset->os_dsl_dataset,
+ bp, bp->blk_birth))
+ txh->txh_space_tooverwrite += SPA_MAXBLOCKSIZE;
+ else
+ txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+ if (bp->blk_birth)
+ txh->txh_space_tounref += SPA_MAXBLOCKSIZE;
+ }
+}
+
+void
+dmu_tx_hold_sa_create(dmu_tx_t *tx, int attrsize)
+{
+ sa_os_t *sa = tx->tx_objset->os_sa;
+
+ dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
+
+ if (tx->tx_objset->os_sa->sa_master_obj == 0)
+ return;
+
+ if (tx->tx_objset->os_sa->sa_layout_attr_obj)
+ dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL);
+ else {
+ dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS);
+ dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY);
+ dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
+ dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
+ }
+
+ dmu_tx_sa_registration_hold(sa, tx);
+
+ if (attrsize <= DN_MAX_BONUSLEN && !sa->sa_force_spill)
+ return;
+
+ (void) dmu_tx_hold_object_impl(tx, tx->tx_objset, DMU_NEW_OBJECT,
+ THT_SPILL, 0, 0);
+}
+
+/*
+ * Hold SA attribute
+ *
+ * dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *, attribute, add, size)
+ *
+ * variable_size is the total size of all variable sized attributes
+ * passed to this function. It is not the total size of all
+ * variable size attributes that *may* exist on this object.
+ */
+void
+dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *hdl, boolean_t may_grow)
+{
+ uint64_t object;
+ sa_os_t *sa = tx->tx_objset->os_sa;
+
+ ASSERT(hdl != NULL);
+
+ object = sa_handle_object(hdl);
+
+ dmu_tx_hold_bonus(tx, object);
+
+ if (tx->tx_objset->os_sa->sa_master_obj == 0)
+ return;
+
+ if (tx->tx_objset->os_sa->sa_reg_attr_obj == 0 ||
+ tx->tx_objset->os_sa->sa_layout_attr_obj == 0) {
+ dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS);
+ dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY);
+ dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
+ dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
+ }
+
+ dmu_tx_sa_registration_hold(sa, tx);
+
+ if (may_grow && tx->tx_objset->os_sa->sa_layout_attr_obj)
+ dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL);
+
+ if (sa->sa_force_spill || may_grow || hdl->sa_spill) {
+ ASSERT(tx->tx_txg == 0);
+ dmu_tx_hold_spill(tx, object);
+ } else {
+ dmu_buf_impl_t *db = (dmu_buf_impl_t *)hdl->sa_bonus;
+ dnode_t *dn;
+
+ DB_DNODE_ENTER(db);
+ dn = DB_DNODE(db);
+ if (dn->dn_have_spill) {
+ ASSERT(tx->tx_txg == 0);
+ dmu_tx_hold_spill(tx, object);
+ }
+ DB_DNODE_EXIT(db);
+ }
+}