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zfs/module/zfs/dnode.c

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/*
* 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 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/zfs_context.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_dataset.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/dmu_zfetch.h>
static int free_range_compar(const void *node1, const void *node2);
static kmem_cache_t *dnode_cache;
#ifndef NDEBUG
static dnode_phys_t dnode_phys_zero;
#endif
int zfs_default_bs = SPA_MINBLOCKSHIFT;
int zfs_default_ibs = DN_MAX_INDBLKSHIFT;
/* ARGSUSED */
static int
dnode_cons(void *arg, void *unused, int kmflag)
{
int i;
dnode_t *dn = arg;
bzero(dn, sizeof (dnode_t));
rw_init(&dn->dn_struct_rwlock, NULL, RW_DEFAULT, NULL);
mutex_init(&dn->dn_mtx, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&dn->dn_dbufs_mtx, NULL, MUTEX_DEFAULT, NULL);
cv_init(&dn->dn_notxholds, NULL, CV_DEFAULT, NULL);
refcount_create(&dn->dn_holds);
refcount_create(&dn->dn_tx_holds);
for (i = 0; i < TXG_SIZE; i++) {
avl_create(&dn->dn_ranges[i], free_range_compar,
sizeof (free_range_t),
offsetof(struct free_range, fr_node));
list_create(&dn->dn_dirty_records[i],
sizeof (dbuf_dirty_record_t),
offsetof(dbuf_dirty_record_t, dr_dirty_node));
}
list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t),
offsetof(dmu_buf_impl_t, db_link));
return (0);
}
/* ARGSUSED */
static void
dnode_dest(void *arg, void *unused)
{
int i;
dnode_t *dn = arg;
rw_destroy(&dn->dn_struct_rwlock);
mutex_destroy(&dn->dn_mtx);
mutex_destroy(&dn->dn_dbufs_mtx);
cv_destroy(&dn->dn_notxholds);
refcount_destroy(&dn->dn_holds);
refcount_destroy(&dn->dn_tx_holds);
for (i = 0; i < TXG_SIZE; i++) {
avl_destroy(&dn->dn_ranges[i]);
list_destroy(&dn->dn_dirty_records[i]);
}
list_destroy(&dn->dn_dbufs);
}
void
dnode_init(void)
{
dnode_cache = kmem_cache_create("dnode_t",
sizeof (dnode_t),
0, dnode_cons, dnode_dest, NULL, NULL, NULL, 0);
}
void
dnode_fini(void)
{
kmem_cache_destroy(dnode_cache);
}
#ifdef ZFS_DEBUG
void
dnode_verify(dnode_t *dn)
{
int drop_struct_lock = FALSE;
ASSERT(dn->dn_phys);
ASSERT(dn->dn_objset);
ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);
if (!(zfs_flags & ZFS_DEBUG_DNODE_VERIFY))
return;
if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
rw_enter(&dn->dn_struct_rwlock, RW_READER);
drop_struct_lock = TRUE;
}
if (dn->dn_phys->dn_type != DMU_OT_NONE || dn->dn_allocated_txg != 0) {
int i;
ASSERT3U(dn->dn_indblkshift, <=, SPA_MAXBLOCKSHIFT);
if (dn->dn_datablkshift) {
ASSERT3U(dn->dn_datablkshift, >=, SPA_MINBLOCKSHIFT);
ASSERT3U(dn->dn_datablkshift, <=, SPA_MAXBLOCKSHIFT);
ASSERT3U(1<<dn->dn_datablkshift, ==, dn->dn_datablksz);
}
ASSERT3U(dn->dn_nlevels, <=, 30);
ASSERT3U(dn->dn_type, <=, DMU_OT_NUMTYPES);
ASSERT3U(dn->dn_nblkptr, >=, 1);
ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
ASSERT3U(dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
ASSERT3U(dn->dn_datablksz, ==,
dn->dn_datablkszsec << SPA_MINBLOCKSHIFT);
ASSERT3U(ISP2(dn->dn_datablksz), ==, dn->dn_datablkshift != 0);
ASSERT3U((dn->dn_nblkptr - 1) * sizeof (blkptr_t) +
dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
for (i = 0; i < TXG_SIZE; i++) {
ASSERT3U(dn->dn_next_nlevels[i], <=, dn->dn_nlevels);
}
}
if (dn->dn_phys->dn_type != DMU_OT_NONE)
ASSERT3U(dn->dn_phys->dn_nlevels, <=, dn->dn_nlevels);
ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || dn->dn_dbuf != NULL);
if (dn->dn_dbuf != NULL) {
ASSERT3P(dn->dn_phys, ==,
(dnode_phys_t *)dn->dn_dbuf->db.db_data +
(dn->dn_object % (dn->dn_dbuf->db.db_size >> DNODE_SHIFT)));
}
if (drop_struct_lock)
rw_exit(&dn->dn_struct_rwlock);
}
#endif
void
dnode_byteswap(dnode_phys_t *dnp)
{
uint64_t *buf64 = (void*)&dnp->dn_blkptr;
int i;
if (dnp->dn_type == DMU_OT_NONE) {
bzero(dnp, sizeof (dnode_phys_t));
return;
}
dnp->dn_datablkszsec = BSWAP_16(dnp->dn_datablkszsec);
dnp->dn_bonuslen = BSWAP_16(dnp->dn_bonuslen);
dnp->dn_maxblkid = BSWAP_64(dnp->dn_maxblkid);
dnp->dn_used = BSWAP_64(dnp->dn_used);
/*
* dn_nblkptr is only one byte, so it's OK to read it in either
* byte order. We can't read dn_bouslen.
*/
ASSERT(dnp->dn_indblkshift <= SPA_MAXBLOCKSHIFT);
ASSERT(dnp->dn_nblkptr <= DN_MAX_NBLKPTR);
for (i = 0; i < dnp->dn_nblkptr * sizeof (blkptr_t)/8; i++)
buf64[i] = BSWAP_64(buf64[i]);
/*
* OK to check dn_bonuslen for zero, because it won't matter if
* we have the wrong byte order. This is necessary because the
* dnode dnode is smaller than a regular dnode.
*/
if (dnp->dn_bonuslen != 0) {
/*
* Note that the bonus length calculated here may be
* longer than the actual bonus buffer. This is because
* we always put the bonus buffer after the last block
* pointer (instead of packing it against the end of the
* dnode buffer).
*/
int off = (dnp->dn_nblkptr-1) * sizeof (blkptr_t);
size_t len = DN_MAX_BONUSLEN - off;
ASSERT3U(dnp->dn_bonustype, <, DMU_OT_NUMTYPES);
dmu_ot[dnp->dn_bonustype].ot_byteswap(dnp->dn_bonus + off, len);
}
}
void
dnode_buf_byteswap(void *vbuf, size_t size)
{
dnode_phys_t *buf = vbuf;
int i;
ASSERT3U(sizeof (dnode_phys_t), ==, (1<<DNODE_SHIFT));
ASSERT((size & (sizeof (dnode_phys_t)-1)) == 0);
size >>= DNODE_SHIFT;
for (i = 0; i < size; i++) {
dnode_byteswap(buf);
buf++;
}
}
static int
free_range_compar(const void *node1, const void *node2)
{
const free_range_t *rp1 = node1;
const free_range_t *rp2 = node2;
if (rp1->fr_blkid < rp2->fr_blkid)
return (-1);
else if (rp1->fr_blkid > rp2->fr_blkid)
return (1);
else return (0);
}
void
dnode_setbonuslen(dnode_t *dn, int newsize, dmu_tx_t *tx)
{
ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
dnode_setdirty(dn, tx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
ASSERT3U(newsize, <=, DN_MAX_BONUSLEN -
(dn->dn_nblkptr-1) * sizeof (blkptr_t));
dn->dn_bonuslen = newsize;
if (newsize == 0)
dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = DN_ZERO_BONUSLEN;
else
dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
rw_exit(&dn->dn_struct_rwlock);
}
static void
dnode_setdblksz(dnode_t *dn, int size)
{
ASSERT3U(P2PHASE(size, SPA_MINBLOCKSIZE), ==, 0);
ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
ASSERT3U(size, >=, SPA_MINBLOCKSIZE);
ASSERT3U(size >> SPA_MINBLOCKSHIFT, <,
1<<(sizeof (dn->dn_phys->dn_datablkszsec) * 8));
dn->dn_datablksz = size;
dn->dn_datablkszsec = size >> SPA_MINBLOCKSHIFT;
dn->dn_datablkshift = ISP2(size) ? highbit(size - 1) : 0;
}
static dnode_t *
dnode_create(objset_impl_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db,
uint64_t object)
{
dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP);
dn->dn_objset = os;
dn->dn_object = object;
dn->dn_dbuf = db;
dn->dn_phys = dnp;
list_link_init(&dn->dn_link);
{
int i;
for (i = 0; i < TXG_SIZE; i++)
list_link_init(&dn->dn_dirty_link[i]);
}
if (dnp->dn_datablkszsec)
dnode_setdblksz(dn, dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
dn->dn_indblkshift = dnp->dn_indblkshift;
dn->dn_nlevels = dnp->dn_nlevels;
dn->dn_type = dnp->dn_type;
dn->dn_nblkptr = dnp->dn_nblkptr;
dn->dn_checksum = dnp->dn_checksum;
dn->dn_compress = dnp->dn_compress;
dn->dn_bonustype = dnp->dn_bonustype;
dn->dn_bonuslen = dnp->dn_bonuslen;
dn->dn_maxblkid = dnp->dn_maxblkid;
dmu_zfetch_init(&dn->dn_zfetch, dn);
ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);
mutex_enter(&os->os_lock);
list_insert_head(&os->os_dnodes, dn);
mutex_exit(&os->os_lock);
arc_space_consume(sizeof (dnode_t));
return (dn);
}
static void
dnode_destroy(dnode_t *dn)
{
objset_impl_t *os = dn->dn_objset;
#ifdef ZFS_DEBUG
int i;
for (i = 0; i < TXG_SIZE; i++) {
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
ASSERT(NULL == list_head(&dn->dn_dirty_records[i]));
ASSERT(0 == avl_numnodes(&dn->dn_ranges[i]));
}
ASSERT(NULL == list_head(&dn->dn_dbufs));
#endif
mutex_enter(&os->os_lock);
list_remove(&os->os_dnodes, dn);
mutex_exit(&os->os_lock);
if (dn->dn_dirtyctx_firstset) {
kmem_free(dn->dn_dirtyctx_firstset, 1);
dn->dn_dirtyctx_firstset = NULL;
}
dmu_zfetch_rele(&dn->dn_zfetch);
if (dn->dn_bonus) {
mutex_enter(&dn->dn_bonus->db_mtx);
dbuf_evict(dn->dn_bonus);
dn->dn_bonus = NULL;
}
kmem_cache_free(dnode_cache, dn);
arc_space_return(sizeof (dnode_t));
}
void
dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
int i;
if (blocksize == 0)
blocksize = 1 << zfs_default_bs;
else if (blocksize > SPA_MAXBLOCKSIZE)
blocksize = SPA_MAXBLOCKSIZE;
else
blocksize = P2ROUNDUP(blocksize, SPA_MINBLOCKSIZE);
if (ibs == 0)
ibs = zfs_default_ibs;
ibs = MIN(MAX(ibs, DN_MIN_INDBLKSHIFT), DN_MAX_INDBLKSHIFT);
dprintf("os=%p obj=%llu txg=%llu blocksize=%d ibs=%d\n", dn->dn_objset,
dn->dn_object, tx->tx_txg, blocksize, ibs);
ASSERT(dn->dn_type == DMU_OT_NONE);
ASSERT(bcmp(dn->dn_phys, &dnode_phys_zero, sizeof (dnode_phys_t)) == 0);
ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE);
ASSERT(ot != DMU_OT_NONE);
ASSERT3U(ot, <, DMU_OT_NUMTYPES);
ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
(bonustype != DMU_OT_NONE && bonuslen != 0));
ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
ASSERT(dn->dn_type == DMU_OT_NONE);
ASSERT3U(dn->dn_maxblkid, ==, 0);
ASSERT3U(dn->dn_allocated_txg, ==, 0);
ASSERT3U(dn->dn_assigned_txg, ==, 0);
ASSERT(refcount_is_zero(&dn->dn_tx_holds));
ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
for (i = 0; i < TXG_SIZE; i++) {
ASSERT3U(dn->dn_next_nlevels[i], ==, 0);
ASSERT3U(dn->dn_next_indblkshift[i], ==, 0);
ASSERT3U(dn->dn_next_bonuslen[i], ==, 0);
ASSERT3U(dn->dn_next_blksz[i], ==, 0);
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
ASSERT3P(list_head(&dn->dn_dirty_records[i]), ==, NULL);
ASSERT3U(avl_numnodes(&dn->dn_ranges[i]), ==, 0);
}
dn->dn_type = ot;
dnode_setdblksz(dn, blocksize);
dn->dn_indblkshift = ibs;
dn->dn_nlevels = 1;
dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
dn->dn_bonustype = bonustype;
dn->dn_bonuslen = bonuslen;
dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
dn->dn_compress = ZIO_COMPRESS_INHERIT;
dn->dn_dirtyctx = 0;
dn->dn_free_txg = 0;
if (dn->dn_dirtyctx_firstset) {
kmem_free(dn->dn_dirtyctx_firstset, 1);
dn->dn_dirtyctx_firstset = NULL;
}
dn->dn_allocated_txg = tx->tx_txg;
dnode_setdirty(dn, tx);
dn->dn_next_indblkshift[tx->tx_txg & TXG_MASK] = ibs;
dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
dn->dn_next_blksz[tx->tx_txg & TXG_MASK] = dn->dn_datablksz;
}
void
dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
int i, old_nblkptr;
dmu_buf_impl_t *db = NULL;
ASSERT3U(blocksize, >=, SPA_MINBLOCKSIZE);
ASSERT3U(blocksize, <=, SPA_MAXBLOCKSIZE);
ASSERT3U(blocksize % SPA_MINBLOCKSIZE, ==, 0);
ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT || dmu_tx_private_ok(tx));
ASSERT(tx->tx_txg != 0);
ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
(bonustype != DMU_OT_NONE && bonuslen != 0));
ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
for (i = 0; i < TXG_SIZE; i++)
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
/* clean up any unreferenced dbufs */
dnode_evict_dbufs(dn);
ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
/*
* XXX I should really have a generation number to tell if we
* need to do this...
*/
if (blocksize != dn->dn_datablksz ||
dn->dn_bonustype != bonustype || dn->dn_bonuslen != bonuslen) {
/* free all old data */
dnode_free_range(dn, 0, -1ULL, tx);
}
/* change blocksize */
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
if (blocksize != dn->dn_datablksz &&
(!BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) ||
list_head(&dn->dn_dbufs) != NULL)) {
db = dbuf_hold(dn, 0, FTAG);
dbuf_new_size(db, blocksize, tx);
}
dnode_setdblksz(dn, blocksize);
dnode_setdirty(dn, tx);
dn->dn_next_bonuslen[tx->tx_txg&TXG_MASK] = bonuslen;
dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = blocksize;
rw_exit(&dn->dn_struct_rwlock);
if (db)
dbuf_rele(db, FTAG);
/* change type */
dn->dn_type = ot;
/* change bonus size and type */
mutex_enter(&dn->dn_mtx);
old_nblkptr = dn->dn_nblkptr;
dn->dn_bonustype = bonustype;
dn->dn_bonuslen = bonuslen;
dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
dn->dn_compress = ZIO_COMPRESS_INHERIT;
ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
/* XXX - for now, we can't make nblkptr smaller */
ASSERT3U(dn->dn_nblkptr, >=, old_nblkptr);
/* fix up the bonus db_size if dn_nblkptr has changed */
if (dn->dn_bonus && dn->dn_bonuslen != old_nblkptr) {
dn->dn_bonus->db.db_size =
DN_MAX_BONUSLEN - (dn->dn_nblkptr-1) * sizeof (blkptr_t);
ASSERT(dn->dn_bonuslen <= dn->dn_bonus->db.db_size);
}
dn->dn_allocated_txg = tx->tx_txg;
mutex_exit(&dn->dn_mtx);
}
void
dnode_special_close(dnode_t *dn)
{
/*
* Wait for final references to the dnode to clear. This can
* only happen if the arc is asyncronously evicting state that
* has a hold on this dnode while we are trying to evict this
* dnode.
*/
while (refcount_count(&dn->dn_holds) > 0)
delay(1);
dnode_destroy(dn);
}
dnode_t *
dnode_special_open(objset_impl_t *os, dnode_phys_t *dnp, uint64_t object)
{
dnode_t *dn = dnode_create(os, dnp, NULL, object);
DNODE_VERIFY(dn);
return (dn);
}
static void
dnode_buf_pageout(dmu_buf_t *db, void *arg)
{
dnode_t **children_dnodes = arg;
int i;
int epb = db->db_size >> DNODE_SHIFT;
for (i = 0; i < epb; i++) {
dnode_t *dn = children_dnodes[i];
if (dn == NULL)
continue;
#ifdef ZFS_DEBUG
{
int n;
/*
* If there are holds on this dnode, then there should
* be holds on the dnode's containing dbuf as well; thus
* it wouldn't be eligable for eviction and this function
* would not have been called.
*/
ASSERT(refcount_is_zero(&dn->dn_holds));
ASSERT(list_head(&dn->dn_dbufs) == NULL);
ASSERT(refcount_is_zero(&dn->dn_tx_holds));
for (n = 0; n < TXG_SIZE; n++)
ASSERT(!list_link_active(&dn->dn_dirty_link[n]));
}
#endif
children_dnodes[i] = NULL;
dnode_destroy(dn);
}
kmem_free(children_dnodes, epb * sizeof (dnode_t *));
}
/*
* errors:
* EINVAL - invalid object number.
* EIO - i/o error.
* succeeds even for free dnodes.
*/
int
dnode_hold_impl(objset_impl_t *os, uint64_t object, int flag,
void *tag, dnode_t **dnp)
{
int epb, idx, err;
int drop_struct_lock = FALSE;
int type;
uint64_t blk;
dnode_t *mdn, *dn;
dmu_buf_impl_t *db;
dnode_t **children_dnodes;
/*
* If you are holding the spa config lock as writer, you shouldn't
* be asking the DMU to do *anything*.
*/
ASSERT(spa_config_held(os->os_spa, SCL_ALL, RW_WRITER) == 0);
if (object == 0 || object >= DN_MAX_OBJECT)
return (EINVAL);
mdn = os->os_meta_dnode;
DNODE_VERIFY(mdn);
if (!RW_WRITE_HELD(&mdn->dn_struct_rwlock)) {
rw_enter(&mdn->dn_struct_rwlock, RW_READER);
drop_struct_lock = TRUE;
}
blk = dbuf_whichblock(mdn, object * sizeof (dnode_phys_t));
db = dbuf_hold(mdn, blk, FTAG);
if (drop_struct_lock)
rw_exit(&mdn->dn_struct_rwlock);
if (db == NULL)
return (EIO);
err = dbuf_read(db, NULL, DB_RF_CANFAIL);
if (err) {
dbuf_rele(db, FTAG);
return (err);
}
ASSERT3U(db->db.db_size, >=, 1<<DNODE_SHIFT);
epb = db->db.db_size >> DNODE_SHIFT;
idx = object & (epb-1);
children_dnodes = dmu_buf_get_user(&db->db);
if (children_dnodes == NULL) {
dnode_t **winner;
children_dnodes = kmem_zalloc(epb * sizeof (dnode_t *),
KM_SLEEP);
if ((winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
dnode_buf_pageout))) {
kmem_free(children_dnodes, epb * sizeof (dnode_t *));
children_dnodes = winner;
}
}
if ((dn = children_dnodes[idx]) == NULL) {
dnode_phys_t *dnpp = (dnode_phys_t *)db->db.db_data+idx;
dnode_t *winner;
dn = dnode_create(os, dnpp, db, object);
winner = atomic_cas_ptr(&children_dnodes[idx], NULL, dn);
if (winner != NULL) {
dnode_destroy(dn);
dn = winner;
}
}
mutex_enter(&dn->dn_mtx);
type = dn->dn_type;
if (dn->dn_free_txg ||
((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE) ||
((flag & DNODE_MUST_BE_FREE) && type != DMU_OT_NONE)) {
mutex_exit(&dn->dn_mtx);
dbuf_rele(db, FTAG);
return (type == DMU_OT_NONE ? ENOENT : EEXIST);
}
mutex_exit(&dn->dn_mtx);
if (refcount_add(&dn->dn_holds, tag) == 1)
dbuf_add_ref(db, dn);
DNODE_VERIFY(dn);
ASSERT3P(dn->dn_dbuf, ==, db);
ASSERT3U(dn->dn_object, ==, object);
dbuf_rele(db, FTAG);
*dnp = dn;
return (0);
}
/*
* Return held dnode if the object is allocated, NULL if not.
*/
int
dnode_hold(objset_impl_t *os, uint64_t object, void *tag, dnode_t **dnp)
{
return (dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, tag, dnp));
}
/*
* Can only add a reference if there is already at least one
* reference on the dnode. Returns FALSE if unable to add a
* new reference.
*/
boolean_t
dnode_add_ref(dnode_t *dn, void *tag)
{
mutex_enter(&dn->dn_mtx);
if (refcount_is_zero(&dn->dn_holds)) {
mutex_exit(&dn->dn_mtx);
return (FALSE);
}
VERIFY(1 < refcount_add(&dn->dn_holds, tag));
mutex_exit(&dn->dn_mtx);
return (TRUE);
}
void
dnode_rele(dnode_t *dn, void *tag)
{
uint64_t refs;
mutex_enter(&dn->dn_mtx);
refs = refcount_remove(&dn->dn_holds, tag);
mutex_exit(&dn->dn_mtx);
/* NOTE: the DNODE_DNODE does not have a dn_dbuf */
if (refs == 0 && dn->dn_dbuf)
dbuf_rele(dn->dn_dbuf, dn);
}
void
dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
{
objset_impl_t *os = dn->dn_objset;
uint64_t txg = tx->tx_txg;
if (dn->dn_object == DMU_META_DNODE_OBJECT)
return;
DNODE_VERIFY(dn);
#ifdef ZFS_DEBUG
mutex_enter(&dn->dn_mtx);
ASSERT(dn->dn_phys->dn_type || dn->dn_allocated_txg);
/* ASSERT(dn->dn_free_txg == 0 || dn->dn_free_txg >= txg); */
mutex_exit(&dn->dn_mtx);
#endif
mutex_enter(&os->os_lock);
/*
* If we are already marked dirty, we're done.
*/
if (list_link_active(&dn->dn_dirty_link[txg & TXG_MASK])) {
mutex_exit(&os->os_lock);
return;
}
ASSERT(!refcount_is_zero(&dn->dn_holds) || list_head(&dn->dn_dbufs));
ASSERT(dn->dn_datablksz != 0);
ASSERT3U(dn->dn_next_bonuslen[txg&TXG_MASK], ==, 0);
ASSERT3U(dn->dn_next_blksz[txg&TXG_MASK], ==, 0);
dprintf_ds(os->os_dsl_dataset, "obj=%llu txg=%llu\n",
dn->dn_object, txg);
if (dn->dn_free_txg > 0 && dn->dn_free_txg <= txg) {
list_insert_tail(&os->os_free_dnodes[txg&TXG_MASK], dn);
} else {
list_insert_tail(&os->os_dirty_dnodes[txg&TXG_MASK], dn);
}
mutex_exit(&os->os_lock);
/*
* The dnode maintains a hold on its containing dbuf as
* long as there are holds on it. Each instantiated child
* dbuf maintaines a hold on the dnode. When the last child
* drops its hold, the dnode will drop its hold on the
* containing dbuf. We add a "dirty hold" here so that the
* dnode will hang around after we finish processing its
* children.
*/
VERIFY(dnode_add_ref(dn, (void *)(uintptr_t)tx->tx_txg));
(void) dbuf_dirty(dn->dn_dbuf, tx);
dsl_dataset_dirty(os->os_dsl_dataset, tx);
}
void
dnode_free(dnode_t *dn, dmu_tx_t *tx)
{
int txgoff = tx->tx_txg & TXG_MASK;
dprintf("dn=%p txg=%llu\n", dn, tx->tx_txg);
/* we should be the only holder... hopefully */
/* ASSERT3U(refcount_count(&dn->dn_holds), ==, 1); */
mutex_enter(&dn->dn_mtx);
if (dn->dn_type == DMU_OT_NONE || dn->dn_free_txg) {
mutex_exit(&dn->dn_mtx);
return;
}
dn->dn_free_txg = tx->tx_txg;
mutex_exit(&dn->dn_mtx);
/*
* If the dnode is already dirty, it needs to be moved from
* the dirty list to the free list.
*/
mutex_enter(&dn->dn_objset->os_lock);
if (list_link_active(&dn->dn_dirty_link[txgoff])) {
list_remove(&dn->dn_objset->os_dirty_dnodes[txgoff], dn);
list_insert_tail(&dn->dn_objset->os_free_dnodes[txgoff], dn);
mutex_exit(&dn->dn_objset->os_lock);
} else {
mutex_exit(&dn->dn_objset->os_lock);
dnode_setdirty(dn, tx);
}
}
/*
* Try to change the block size for the indicated dnode. This can only
* succeed if there are no blocks allocated or dirty beyond first block
*/
int
dnode_set_blksz(dnode_t *dn, uint64_t size, int ibs, dmu_tx_t *tx)
{
dmu_buf_impl_t *db, *db_next;
int err;
if (size == 0)
size = SPA_MINBLOCKSIZE;
if (size > SPA_MAXBLOCKSIZE)
size = SPA_MAXBLOCKSIZE;
else
size = P2ROUNDUP(size, SPA_MINBLOCKSIZE);
if (ibs == dn->dn_indblkshift)
ibs = 0;
if (size >> SPA_MINBLOCKSHIFT == dn->dn_datablkszsec && ibs == 0)
return (0);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
/* Check for any allocated blocks beyond the first */
if (dn->dn_phys->dn_maxblkid != 0)
goto fail;
mutex_enter(&dn->dn_dbufs_mtx);
for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
db_next = list_next(&dn->dn_dbufs, db);
if (db->db_blkid != 0 && db->db_blkid != DB_BONUS_BLKID) {
mutex_exit(&dn->dn_dbufs_mtx);
goto fail;
}
}
mutex_exit(&dn->dn_dbufs_mtx);
if (ibs && dn->dn_nlevels != 1)
goto fail;
/* resize the old block */
err = dbuf_hold_impl(dn, 0, 0, TRUE, FTAG, &db);
if (err == 0)
dbuf_new_size(db, size, tx);
else if (err != ENOENT)
goto fail;
dnode_setdblksz(dn, size);
dnode_setdirty(dn, tx);
dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = size;
if (ibs) {
dn->dn_indblkshift = ibs;
dn->dn_next_indblkshift[tx->tx_txg&TXG_MASK] = ibs;
}
/* rele after we have fixed the blocksize in the dnode */
if (db)
dbuf_rele(db, FTAG);
rw_exit(&dn->dn_struct_rwlock);
return (0);
fail:
rw_exit(&dn->dn_struct_rwlock);
return (ENOTSUP);
}
/* read-holding callers must not rely on the lock being continuously held */
void
dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx, boolean_t have_read)
{
uint64_t txgoff = tx->tx_txg & TXG_MASK;
int epbs, new_nlevels;
uint64_t sz;
ASSERT(blkid != DB_BONUS_BLKID);
ASSERT(have_read ?
RW_READ_HELD(&dn->dn_struct_rwlock) :
RW_WRITE_HELD(&dn->dn_struct_rwlock));
/*
* if we have a read-lock, check to see if we need to do any work
* before upgrading to a write-lock.
*/
if (have_read) {
if (blkid <= dn->dn_maxblkid)
return;
if (!rw_tryupgrade(&dn->dn_struct_rwlock)) {
rw_exit(&dn->dn_struct_rwlock);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
}
}
if (blkid <= dn->dn_maxblkid)
goto out;
dn->dn_maxblkid = blkid;
/*
* Compute the number of levels necessary to support the new maxblkid.
*/
new_nlevels = 1;
epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
for (sz = dn->dn_nblkptr;
sz <= blkid && sz >= dn->dn_nblkptr; sz <<= epbs)
new_nlevels++;
if (new_nlevels > dn->dn_nlevels) {
int old_nlevels = dn->dn_nlevels;
dmu_buf_impl_t *db;
list_t *list;
dbuf_dirty_record_t *new, *dr, *dr_next;
dn->dn_nlevels = new_nlevels;
ASSERT3U(new_nlevels, >, dn->dn_next_nlevels[txgoff]);
dn->dn_next_nlevels[txgoff] = new_nlevels;
/* dirty the left indirects */
db = dbuf_hold_level(dn, old_nlevels, 0, FTAG);
new = dbuf_dirty(db, tx);
dbuf_rele(db, FTAG);
/* transfer the dirty records to the new indirect */
mutex_enter(&dn->dn_mtx);
mutex_enter(&new->dt.di.dr_mtx);
list = &dn->dn_dirty_records[txgoff];
for (dr = list_head(list); dr; dr = dr_next) {
dr_next = list_next(&dn->dn_dirty_records[txgoff], dr);
if (dr->dr_dbuf->db_level != new_nlevels-1 &&
dr->dr_dbuf->db_blkid != DB_BONUS_BLKID) {
ASSERT(dr->dr_dbuf->db_level == old_nlevels-1);
list_remove(&dn->dn_dirty_records[txgoff], dr);
list_insert_tail(&new->dt.di.dr_children, dr);
dr->dr_parent = new;
}
}
mutex_exit(&new->dt.di.dr_mtx);
mutex_exit(&dn->dn_mtx);
}
out:
if (have_read)
rw_downgrade(&dn->dn_struct_rwlock);
}
void
dnode_clear_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
{
avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
avl_index_t where;
free_range_t *rp;
free_range_t rp_tofind;
uint64_t endblk = blkid + nblks;
ASSERT(MUTEX_HELD(&dn->dn_mtx));
ASSERT(nblks <= UINT64_MAX - blkid); /* no overflow */
dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
blkid, nblks, tx->tx_txg);
rp_tofind.fr_blkid = blkid;
rp = avl_find(tree, &rp_tofind, &where);
if (rp == NULL)
rp = avl_nearest(tree, where, AVL_BEFORE);
if (rp == NULL)
rp = avl_nearest(tree, where, AVL_AFTER);
while (rp && (rp->fr_blkid <= blkid + nblks)) {
uint64_t fr_endblk = rp->fr_blkid + rp->fr_nblks;
free_range_t *nrp = AVL_NEXT(tree, rp);
if (blkid <= rp->fr_blkid && endblk >= fr_endblk) {
/* clear this entire range */
avl_remove(tree, rp);
kmem_free(rp, sizeof (free_range_t));
} else if (blkid <= rp->fr_blkid &&
endblk > rp->fr_blkid && endblk < fr_endblk) {
/* clear the beginning of this range */
rp->fr_blkid = endblk;
rp->fr_nblks = fr_endblk - endblk;
} else if (blkid > rp->fr_blkid && blkid < fr_endblk &&
endblk >= fr_endblk) {
/* clear the end of this range */
rp->fr_nblks = blkid - rp->fr_blkid;
} else if (blkid > rp->fr_blkid && endblk < fr_endblk) {
/* clear a chunk out of this range */
free_range_t *new_rp =
kmem_alloc(sizeof (free_range_t), KM_SLEEP);
new_rp->fr_blkid = endblk;
new_rp->fr_nblks = fr_endblk - endblk;
avl_insert_here(tree, new_rp, rp, AVL_AFTER);
rp->fr_nblks = blkid - rp->fr_blkid;
}
/* there may be no overlap */
rp = nrp;
}
}
void
dnode_free_range(dnode_t *dn, uint64_t off, uint64_t len, dmu_tx_t *tx)
{
dmu_buf_impl_t *db;
uint64_t blkoff, blkid, nblks;
int blksz, blkshift, head, tail;
int trunc = FALSE;
int epbs;
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
blksz = dn->dn_datablksz;
blkshift = dn->dn_datablkshift;
epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
if (len == -1ULL) {
len = UINT64_MAX - off;
trunc = TRUE;
}
/*
* First, block align the region to free:
*/
if (ISP2(blksz)) {
head = P2NPHASE(off, blksz);
blkoff = P2PHASE(off, blksz);
if ((off >> blkshift) > dn->dn_maxblkid)
goto out;
} else {
ASSERT(dn->dn_maxblkid == 0);
if (off == 0 && len >= blksz) {
/* Freeing the whole block; fast-track this request */
blkid = 0;
nblks = 1;
goto done;
} else if (off >= blksz) {
/* Freeing past end-of-data */
goto out;
} else {
/* Freeing part of the block. */
head = blksz - off;
ASSERT3U(head, >, 0);
}
blkoff = off;
}
/* zero out any partial block data at the start of the range */
if (head) {
ASSERT3U(blkoff + head, ==, blksz);
if (len < head)
head = len;
if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off), TRUE,
FTAG, &db) == 0) {
caddr_t data;
/* don't dirty if it isn't on disk and isn't dirty */
if (db->db_last_dirty ||
(db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
rw_exit(&dn->dn_struct_rwlock);
dbuf_will_dirty(db, tx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
data = db->db.db_data;
bzero(data + blkoff, head);
}
dbuf_rele(db, FTAG);
}
off += head;
len -= head;
}
/* If the range was less than one block, we're done */
if (len == 0)
goto out;
/* If the remaining range is past end of file, we're done */
if ((off >> blkshift) > dn->dn_maxblkid)
goto out;
ASSERT(ISP2(blksz));
if (trunc)
tail = 0;
else
tail = P2PHASE(len, blksz);
ASSERT3U(P2PHASE(off, blksz), ==, 0);
/* zero out any partial block data at the end of the range */
if (tail) {
if (len < tail)
tail = len;
if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off+len),
TRUE, FTAG, &db) == 0) {
/* don't dirty if not on disk and not dirty */
if (db->db_last_dirty ||
(db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
rw_exit(&dn->dn_struct_rwlock);
dbuf_will_dirty(db, tx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
bzero(db->db.db_data, tail);
}
dbuf_rele(db, FTAG);
}
len -= tail;
}
/* If the range did not include a full block, we are done */
if (len == 0)
goto out;
ASSERT(IS_P2ALIGNED(off, blksz));
ASSERT(trunc || IS_P2ALIGNED(len, blksz));
blkid = off >> blkshift;
nblks = len >> blkshift;
if (trunc)
nblks += 1;
/*
* Read in and mark all the level-1 indirects dirty,
* so that they will stay in memory until syncing phase.
* Always dirty the first and last indirect to make sure
* we dirty all the partial indirects.
*/
if (dn->dn_nlevels > 1) {
uint64_t i, first, last;
int shift = epbs + dn->dn_datablkshift;
first = blkid >> epbs;
if (db = dbuf_hold_level(dn, 1, first, FTAG)) {
dbuf_will_dirty(db, tx);
dbuf_rele(db, FTAG);
}
if (trunc)
last = dn->dn_maxblkid >> epbs;
else
last = (blkid + nblks - 1) >> epbs;
if (last > first && (db = dbuf_hold_level(dn, 1, last, FTAG))) {
dbuf_will_dirty(db, tx);
dbuf_rele(db, FTAG);
}
for (i = first + 1; i < last; i++) {
uint64_t ibyte = i << shift;
int err;
err = dnode_next_offset(dn,
DNODE_FIND_HAVELOCK, &ibyte, 1, 1, 0);
i = ibyte >> shift;
if (err == ESRCH || i >= last)
break;
ASSERT(err == 0);
db = dbuf_hold_level(dn, 1, i, FTAG);
if (db) {
dbuf_will_dirty(db, tx);
dbuf_rele(db, FTAG);
}
}
}
done:
/*
* Add this range to the dnode range list.
* We will finish up this free operation in the syncing phase.
*/
mutex_enter(&dn->dn_mtx);
dnode_clear_range(dn, blkid, nblks, tx);
{
free_range_t *rp, *found;
avl_index_t where;
avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
/* Add new range to dn_ranges */
rp = kmem_alloc(sizeof (free_range_t), KM_SLEEP);
rp->fr_blkid = blkid;
rp->fr_nblks = nblks;
found = avl_find(tree, rp, &where);
ASSERT(found == NULL);
avl_insert(tree, rp, where);
dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
blkid, nblks, tx->tx_txg);
}
mutex_exit(&dn->dn_mtx);
dbuf_free_range(dn, blkid, blkid + nblks - 1, tx);
dnode_setdirty(dn, tx);
out:
if (trunc && dn->dn_maxblkid >= (off >> blkshift))
dn->dn_maxblkid = (off >> blkshift ? (off >> blkshift) - 1 : 0);
rw_exit(&dn->dn_struct_rwlock);
}
/* return TRUE if this blkid was freed in a recent txg, or FALSE if it wasn't */
uint64_t
dnode_block_freed(dnode_t *dn, uint64_t blkid)
{
free_range_t range_tofind;
void *dp = spa_get_dsl(dn->dn_objset->os_spa);
int i;
if (blkid == DB_BONUS_BLKID)
return (FALSE);
/*
* If we're in the process of opening the pool, dp will not be
* set yet, but there shouldn't be anything dirty.
*/
if (dp == NULL)
return (FALSE);
if (dn->dn_free_txg)
return (TRUE);
/*
* If dn_datablkshift is not set, then there's only a single
* block, in which case there will never be a free range so it
* won't matter.
*/
range_tofind.fr_blkid = blkid;
mutex_enter(&dn->dn_mtx);
for (i = 0; i < TXG_SIZE; i++) {
free_range_t *range_found;
avl_index_t idx;
range_found = avl_find(&dn->dn_ranges[i], &range_tofind, &idx);
if (range_found) {
ASSERT(range_found->fr_nblks > 0);
break;
}
range_found = avl_nearest(&dn->dn_ranges[i], idx, AVL_BEFORE);
if (range_found &&
range_found->fr_blkid + range_found->fr_nblks > blkid)
break;
}
mutex_exit(&dn->dn_mtx);
return (i < TXG_SIZE);
}
/* call from syncing context when we actually write/free space for this dnode */
void
dnode_diduse_space(dnode_t *dn, int64_t delta)
{
uint64_t space;
dprintf_dnode(dn, "dn=%p dnp=%p used=%llu delta=%lld\n",
dn, dn->dn_phys,
(u_longlong_t)dn->dn_phys->dn_used,
(longlong_t)delta);
mutex_enter(&dn->dn_mtx);
space = DN_USED_BYTES(dn->dn_phys);
if (delta > 0) {
ASSERT3U(space + delta, >=, space); /* no overflow */
} else {
ASSERT3U(space, >=, -delta); /* no underflow */
}
space += delta;
if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_DNODE_BYTES) {
ASSERT((dn->dn_phys->dn_flags & DNODE_FLAG_USED_BYTES) == 0);
ASSERT3U(P2PHASE(space, 1<<DEV_BSHIFT), ==, 0);
dn->dn_phys->dn_used = space >> DEV_BSHIFT;
} else {
dn->dn_phys->dn_used = space;
dn->dn_phys->dn_flags |= DNODE_FLAG_USED_BYTES;
}
mutex_exit(&dn->dn_mtx);
}
/*
* Call when we think we're going to write/free space in open context.
* Be conservative (ie. OK to write less than this or free more than
* this, but don't write more or free less).
*/
void
dnode_willuse_space(dnode_t *dn, int64_t space, dmu_tx_t *tx)
{
objset_impl_t *os = dn->dn_objset;
dsl_dataset_t *ds = os->os_dsl_dataset;
if (space > 0)
space = spa_get_asize(os->os_spa, space);
if (ds)
dsl_dir_willuse_space(ds->ds_dir, space, tx);
dmu_tx_willuse_space(tx, space);
}
static int
dnode_next_offset_level(dnode_t *dn, int flags, uint64_t *offset,
int lvl, uint64_t blkfill, uint64_t txg)
{
dmu_buf_impl_t *db = NULL;
void *data = NULL;
uint64_t epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
uint64_t epb = 1ULL << epbs;
uint64_t minfill, maxfill;
boolean_t hole;
int i, inc, error, span;
dprintf("probing object %llu offset %llx level %d of %u\n",
dn->dn_object, *offset, lvl, dn->dn_phys->dn_nlevels);
hole = flags & DNODE_FIND_HOLE;
inc = (flags & DNODE_FIND_BACKWARDS) ? -1 : 1;
ASSERT(txg == 0 || !hole);
if (lvl == dn->dn_phys->dn_nlevels) {
error = 0;
epb = dn->dn_phys->dn_nblkptr;
data = dn->dn_phys->dn_blkptr;
} else {
uint64_t blkid = dbuf_whichblock(dn, *offset) >> (epbs * lvl);
error = dbuf_hold_impl(dn, lvl, blkid, TRUE, FTAG, &db);
if (error) {
if (error != ENOENT)
return (error);
if (hole)
return (0);
/*
* This can only happen when we are searching up
* the block tree for data. We don't really need to
* adjust the offset, as we will just end up looking
* at the pointer to this block in its parent, and its
* going to be unallocated, so we will skip over it.
*/
return (ESRCH);
}
error = dbuf_read(db, NULL, DB_RF_CANFAIL | DB_RF_HAVESTRUCT);
if (error) {
dbuf_rele(db, FTAG);
return (error);
}
data = db->db.db_data;
}
if (db && txg &&
(db->db_blkptr == NULL || db->db_blkptr->blk_birth <= txg)) {
/*
* This can only happen when we are searching up the tree
* and these conditions mean that we need to keep climbing.
*/
error = ESRCH;
} else if (lvl == 0) {
dnode_phys_t *dnp = data;
span = DNODE_SHIFT;
ASSERT(dn->dn_type == DMU_OT_DNODE);
for (i = (*offset >> span) & (blkfill - 1);
i >= 0 && i < blkfill; i += inc) {
boolean_t newcontents = B_TRUE;
if (txg) {
int j;
newcontents = B_FALSE;
for (j = 0; j < dnp[i].dn_nblkptr; j++) {
if (dnp[i].dn_blkptr[j].blk_birth > txg)
newcontents = B_TRUE;
}
}
if (!dnp[i].dn_type == hole && newcontents)
break;
*offset += (1ULL << span) * inc;
}
if (i < 0 || i == blkfill)
error = ESRCH;
} else {
blkptr_t *bp = data;
span = (lvl - 1) * epbs + dn->dn_datablkshift;
minfill = 0;
maxfill = blkfill << ((lvl - 1) * epbs);
if (hole)
maxfill--;
else
minfill++;
for (i = (*offset >> span) & ((1ULL << epbs) - 1);
i >= 0 && i < epb; i += inc) {
if (bp[i].blk_fill >= minfill &&
bp[i].blk_fill <= maxfill &&
(hole || bp[i].blk_birth > txg))
break;
if (inc < 0 && *offset < (1ULL << span))
*offset = 0;
else
*offset += (1ULL << span) * inc;
}
if (i < 0 || i == epb)
error = ESRCH;
}
if (db)
dbuf_rele(db, FTAG);
return (error);
}
/*
* Find the next hole, data, or sparse region at or after *offset.
* The value 'blkfill' tells us how many items we expect to find
* in an L0 data block; this value is 1 for normal objects,
* DNODES_PER_BLOCK for the meta dnode, and some fraction of
* DNODES_PER_BLOCK when searching for sparse regions thereof.
*
* Examples:
*
* dnode_next_offset(dn, flags, offset, 1, 1, 0);
* Finds the next/previous hole/data in a file.
* Used in dmu_offset_next().
*
* dnode_next_offset(mdn, flags, offset, 0, DNODES_PER_BLOCK, txg);
* Finds the next free/allocated dnode an objset's meta-dnode.
* Only finds objects that have new contents since txg (ie.
* bonus buffer changes and content removal are ignored).
* Used in dmu_object_next().
*
* dnode_next_offset(mdn, DNODE_FIND_HOLE, offset, 2, DNODES_PER_BLOCK >> 2, 0);
* Finds the next L2 meta-dnode bp that's at most 1/4 full.
* Used in dmu_object_alloc().
*/
int
dnode_next_offset(dnode_t *dn, int flags, uint64_t *offset,
int minlvl, uint64_t blkfill, uint64_t txg)
{
uint64_t initial_offset = *offset;
int lvl, maxlvl;
int error = 0;
if (!(flags & DNODE_FIND_HAVELOCK))
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (dn->dn_phys->dn_nlevels == 0) {
error = ESRCH;
goto out;
}
if (dn->dn_datablkshift == 0) {
if (*offset < dn->dn_datablksz) {
if (flags & DNODE_FIND_HOLE)
*offset = dn->dn_datablksz;
} else {
error = ESRCH;
}
goto out;
}
maxlvl = dn->dn_phys->dn_nlevels;
for (lvl = minlvl; lvl <= maxlvl; lvl++) {
error = dnode_next_offset_level(dn,
flags, offset, lvl, blkfill, txg);
if (error != ESRCH)
break;
}
while (error == 0 && --lvl >= minlvl) {
error = dnode_next_offset_level(dn,
flags, offset, lvl, blkfill, txg);
}
if (error == 0 && (flags & DNODE_FIND_BACKWARDS ?
initial_offset < *offset : initial_offset > *offset))
error = ESRCH;
out:
if (!(flags & DNODE_FIND_HAVELOCK))
rw_exit(&dn->dn_struct_rwlock);
return (error);
}
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