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mirror_zfs/module/zfs/dnode.c
Brian Behlendorf ae6ba3dbe6 Improve meta data performance 
Profiling the system during meta data intensive workloads such
as creating/removing millions of files, revealed that the system
was cpu bound.  A large fraction of that cpu time was being spent
waiting on the virtual address space spin lock.

It turns out this was caused by certain heavily used kmem_caches
being backed by virtual memory.  By default a kmem_cache will
dynamically determine the type of memory used based on the object
size.  For large objects virtual memory is usually preferable
and for small object physical memory is a better choice.  See
the spl_slab_alloc() function for a longer discussion on this.

However, there is a certain amount of gray area when defining a
'large' object.  For the following caches it turns out they were
just over the line:

  * dnode_cache
  * zio_cache
  * zio_link_cache
  * zio_buf_512_cache
  * zfs_data_buf_512_cache

Now because we know there will be a lot of churn in these caches,
and because we know the slabs will still be reasonably sized.
We can safely request with the KMC_KMEM flag that the caches be
backed with physical memory addresses.  This entirely avoids the
need to serialize on the virtual address space lock.

As a bonus this also reduces our vmalloc usage which will be good
for 32-bit kernels which have a very small virtual address space.
It will also probably be good for interactive performance since
unrelated processes could also block of this same global lock.
Finally, we may see less cpu time being burned in the arc_reclaim
and txg_sync_threads.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #258
2011-11-03 10:19:21 -07:00

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55 KiB
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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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
*/
#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;
/*
* Define DNODE_STATS to turn on statistic gathering. By default, it is only
* turned on when DEBUG is also defined.
*/
#ifdef DEBUG
#define DNODE_STATS
#endif /* DEBUG */
#ifdef DNODE_STATS
#define DNODE_STAT_ADD(stat) ((stat)++)
#else
#define DNODE_STAT_ADD(stat) /* nothing */
#endif /* DNODE_STATS */
ASSERTV(static dnode_phys_t dnode_phys_zero);
int zfs_default_bs = SPA_MINBLOCKSHIFT;
int zfs_default_ibs = DN_MAX_INDBLKSHIFT;
#ifdef _KERNEL
static kmem_cbrc_t dnode_move(void *, void *, size_t, void *);
#endif /* _KERNEL */
/* ARGSUSED */
static int
dnode_cons(void *arg, void *unused, int kmflag)
{
dnode_t *dn = arg;
int i;
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);
list_link_init(&dn->dn_link);
bzero(&dn->dn_next_nblkptr[0], sizeof (dn->dn_next_nblkptr));
bzero(&dn->dn_next_nlevels[0], sizeof (dn->dn_next_nlevels));
bzero(&dn->dn_next_indblkshift[0], sizeof (dn->dn_next_indblkshift));
bzero(&dn->dn_next_bonustype[0], sizeof (dn->dn_next_bonustype));
bzero(&dn->dn_rm_spillblk[0], sizeof (dn->dn_rm_spillblk));
bzero(&dn->dn_next_bonuslen[0], sizeof (dn->dn_next_bonuslen));
bzero(&dn->dn_next_blksz[0], sizeof (dn->dn_next_blksz));
for (i = 0; i < TXG_SIZE; i++) {
list_link_init(&dn->dn_dirty_link[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));
}
dn->dn_allocated_txg = 0;
dn->dn_free_txg = 0;
dn->dn_assigned_txg = 0;
dn->dn_dirtyctx = 0;
dn->dn_dirtyctx_firstset = NULL;
dn->dn_bonus = NULL;
dn->dn_have_spill = B_FALSE;
dn->dn_zio = NULL;
dn->dn_oldused = 0;
dn->dn_oldflags = 0;
dn->dn_olduid = 0;
dn->dn_oldgid = 0;
dn->dn_newuid = 0;
dn->dn_newgid = 0;
dn->dn_id_flags = 0;
dn->dn_dbufs_count = 0;
list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t),
offsetof(dmu_buf_impl_t, db_link));
dn->dn_moved = 0;
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);
ASSERT(!list_link_active(&dn->dn_link));
for (i = 0; i < TXG_SIZE; i++) {
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
avl_destroy(&dn->dn_ranges[i]);
list_destroy(&dn->dn_dirty_records[i]);
ASSERT3U(dn->dn_next_nblkptr[i], ==, 0);
ASSERT3U(dn->dn_next_nlevels[i], ==, 0);
ASSERT3U(dn->dn_next_indblkshift[i], ==, 0);
ASSERT3U(dn->dn_next_bonustype[i], ==, 0);
ASSERT3U(dn->dn_rm_spillblk[i], ==, 0);
ASSERT3U(dn->dn_next_bonuslen[i], ==, 0);
ASSERT3U(dn->dn_next_blksz[i], ==, 0);
}
ASSERT3U(dn->dn_allocated_txg, ==, 0);
ASSERT3U(dn->dn_free_txg, ==, 0);
ASSERT3U(dn->dn_assigned_txg, ==, 0);
ASSERT3U(dn->dn_dirtyctx, ==, 0);
ASSERT3P(dn->dn_dirtyctx_firstset, ==, NULL);
ASSERT3P(dn->dn_bonus, ==, NULL);
ASSERT(!dn->dn_have_spill);
ASSERT3P(dn->dn_zio, ==, NULL);
ASSERT3U(dn->dn_oldused, ==, 0);
ASSERT3U(dn->dn_oldflags, ==, 0);
ASSERT3U(dn->dn_olduid, ==, 0);
ASSERT3U(dn->dn_oldgid, ==, 0);
ASSERT3U(dn->dn_newuid, ==, 0);
ASSERT3U(dn->dn_newgid, ==, 0);
ASSERT3U(dn->dn_id_flags, ==, 0);
ASSERT3U(dn->dn_dbufs_count, ==, 0);
list_destroy(&dn->dn_dbufs);
}
void
dnode_init(void)
{
ASSERT(dnode_cache == NULL);
dnode_cache = kmem_cache_create("dnode_t", sizeof (dnode_t),
0, dnode_cons, dnode_dest, NULL, NULL, NULL, KMC_KMEM);
kmem_cache_set_move(dnode_cache, dnode_move);
}
void
dnode_fini(void)
{
kmem_cache_destroy(dnode_cache);
dnode_cache = NULL;
}
#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_handle->dnh_dnode == dn);
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(DMU_OBJECT_IS_SPECIAL(dn->dn_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);
}
/* Swap SPILL block if we have one */
if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)
byteswap_uint64_array(&dnp->dn_spill, sizeof (blkptr_t));
}
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);
}
void
dnode_setbonus_type(dnode_t *dn, dmu_object_type_t newtype, dmu_tx_t *tx)
{
ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
dnode_setdirty(dn, tx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
dn->dn_bonustype = newtype;
dn->dn_next_bonustype[tx->tx_txg & TXG_MASK] = dn->dn_bonustype;
rw_exit(&dn->dn_struct_rwlock);
}
void
dnode_rm_spill(dnode_t *dn, dmu_tx_t *tx)
{
ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
dnode_setdirty(dn, tx);
dn->dn_rm_spillblk[tx->tx_txg&TXG_MASK] = DN_KILL_SPILLBLK;
dn->dn_have_spill = B_FALSE;
}
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_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db,
uint64_t object, dnode_handle_t *dnh)
{
dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP);
ASSERT(!POINTER_IS_VALID(dn->dn_objset));
dn->dn_moved = 0;
/*
* Defer setting dn_objset until the dnode is ready to be a candidate
* for the dnode_move() callback.
*/
dn->dn_object = object;
dn->dn_dbuf = db;
dn->dn_handle = dnh;
dn->dn_phys = dnp;
if (dnp->dn_datablkszsec) {
dnode_setdblksz(dn, dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
} else {
dn->dn_datablksz = 0;
dn->dn_datablkszsec = 0;
dn->dn_datablkshift = 0;
}
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;
dn->dn_have_spill = ((dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) != 0);
dn->dn_id_flags = 0;
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);
membar_producer();
/*
* Everything else must be valid before assigning dn_objset makes the
* dnode eligible for dnode_move().
*/
dn->dn_objset = os;
mutex_exit(&os->os_lock);
arc_space_consume(sizeof (dnode_t), ARC_SPACE_OTHER);
return (dn);
}
/*
* Caller must be holding the dnode handle, which is released upon return.
*/
static void
dnode_destroy(dnode_t *dn)
{
objset_t *os = dn->dn_objset;
ASSERT((dn->dn_id_flags & DN_ID_NEW_EXIST) == 0);
mutex_enter(&os->os_lock);
POINTER_INVALIDATE(&dn->dn_objset);
list_remove(&os->os_dnodes, dn);
mutex_exit(&os->os_lock);
/* the dnode can no longer move, so we can release the handle */
zrl_remove(&dn->dn_handle->dnh_zrlock);
dn->dn_allocated_txg = 0;
dn->dn_free_txg = 0;
dn->dn_assigned_txg = 0;
dn->dn_dirtyctx = 0;
if (dn->dn_dirtyctx_firstset != NULL) {
kmem_free(dn->dn_dirtyctx_firstset, 1);
dn->dn_dirtyctx_firstset = NULL;
}
if (dn->dn_bonus != NULL) {
mutex_enter(&dn->dn_bonus->db_mtx);
dbuf_evict(dn->dn_bonus);
dn->dn_bonus = NULL;
}
dn->dn_zio = NULL;
dn->dn_have_spill = B_FALSE;
dn->dn_oldused = 0;
dn->dn_oldflags = 0;
dn->dn_olduid = 0;
dn->dn_oldgid = 0;
dn->dn_newuid = 0;
dn->dn_newgid = 0;
dn->dn_id_flags = 0;
dmu_zfetch_rele(&dn->dn_zfetch);
kmem_cache_free(dnode_cache, dn);
arc_space_return(sizeof (dnode_t), ARC_SPACE_OTHER);
}
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_SA && 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_nblkptr[i], ==, 0);
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_bonustype[i], ==, 0);
ASSERT3U(dn->dn_rm_spillblk[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;
if (bonustype == DMU_OT_SA) /* Maximize bonus space for SA */
dn->dn_nblkptr = 1;
else
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;
dn->dn_id_flags = 0;
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_bonustype[tx->tx_txg & TXG_MASK] = dn->dn_bonustype;
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 nblkptr;
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) ||
(bonustype == DMU_OT_SA && bonuslen == 0));
ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
/* clean up any unreferenced dbufs */
dnode_evict_dbufs(dn);
dn->dn_id_flags = 0;
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
dnode_setdirty(dn, tx);
if (dn->dn_datablksz != blocksize) {
/* change blocksize */
ASSERT(dn->dn_maxblkid == 0 &&
(BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) ||
dnode_block_freed(dn, 0)));
dnode_setdblksz(dn, blocksize);
dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = blocksize;
}
if (dn->dn_bonuslen != bonuslen)
dn->dn_next_bonuslen[tx->tx_txg&TXG_MASK] = bonuslen;
if (bonustype == DMU_OT_SA) /* Maximize bonus space for SA */
nblkptr = 1;
else
nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
if (dn->dn_bonustype != bonustype)
dn->dn_next_bonustype[tx->tx_txg&TXG_MASK] = bonustype;
if (dn->dn_nblkptr != nblkptr)
dn->dn_next_nblkptr[tx->tx_txg&TXG_MASK] = nblkptr;
if (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
dbuf_rm_spill(dn, tx);
dnode_rm_spill(dn, tx);
}
rw_exit(&dn->dn_struct_rwlock);
/* change type */
dn->dn_type = ot;
/* change bonus size and type */
mutex_enter(&dn->dn_mtx);
dn->dn_bonustype = bonustype;
dn->dn_bonuslen = bonuslen;
dn->dn_nblkptr = nblkptr;
dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
dn->dn_compress = ZIO_COMPRESS_INHERIT;
ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
/* fix up the bonus db_size */
if (dn->dn_bonus) {
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);
}
#ifdef _KERNEL
#ifdef DNODE_STATS
static struct {
uint64_t dms_dnode_invalid;
uint64_t dms_dnode_recheck1;
uint64_t dms_dnode_recheck2;
uint64_t dms_dnode_special;
uint64_t dms_dnode_handle;
uint64_t dms_dnode_rwlock;
uint64_t dms_dnode_active;
} dnode_move_stats;
#endif /* DNODE_STATS */
static void
dnode_move_impl(dnode_t *odn, dnode_t *ndn)
{
int i;
ASSERT(!RW_LOCK_HELD(&odn->dn_struct_rwlock));
ASSERT(MUTEX_NOT_HELD(&odn->dn_mtx));
ASSERT(MUTEX_NOT_HELD(&odn->dn_dbufs_mtx));
ASSERT(!RW_LOCK_HELD(&odn->dn_zfetch.zf_rwlock));
/* Copy fields. */
ndn->dn_objset = odn->dn_objset;
ndn->dn_object = odn->dn_object;
ndn->dn_dbuf = odn->dn_dbuf;
ndn->dn_handle = odn->dn_handle;
ndn->dn_phys = odn->dn_phys;
ndn->dn_type = odn->dn_type;
ndn->dn_bonuslen = odn->dn_bonuslen;
ndn->dn_bonustype = odn->dn_bonustype;
ndn->dn_nblkptr = odn->dn_nblkptr;
ndn->dn_checksum = odn->dn_checksum;
ndn->dn_compress = odn->dn_compress;
ndn->dn_nlevels = odn->dn_nlevels;
ndn->dn_indblkshift = odn->dn_indblkshift;
ndn->dn_datablkshift = odn->dn_datablkshift;
ndn->dn_datablkszsec = odn->dn_datablkszsec;
ndn->dn_datablksz = odn->dn_datablksz;
ndn->dn_maxblkid = odn->dn_maxblkid;
bcopy(&odn->dn_next_nblkptr[0], &ndn->dn_next_nblkptr[0],
sizeof (odn->dn_next_nblkptr));
bcopy(&odn->dn_next_nlevels[0], &ndn->dn_next_nlevels[0],
sizeof (odn->dn_next_nlevels));
bcopy(&odn->dn_next_indblkshift[0], &ndn->dn_next_indblkshift[0],
sizeof (odn->dn_next_indblkshift));
bcopy(&odn->dn_next_bonustype[0], &ndn->dn_next_bonustype[0],
sizeof (odn->dn_next_bonustype));
bcopy(&odn->dn_rm_spillblk[0], &ndn->dn_rm_spillblk[0],
sizeof (odn->dn_rm_spillblk));
bcopy(&odn->dn_next_bonuslen[0], &ndn->dn_next_bonuslen[0],
sizeof (odn->dn_next_bonuslen));
bcopy(&odn->dn_next_blksz[0], &ndn->dn_next_blksz[0],
sizeof (odn->dn_next_blksz));
for (i = 0; i < TXG_SIZE; i++) {
list_move_tail(&ndn->dn_dirty_records[i],
&odn->dn_dirty_records[i]);
}
bcopy(&odn->dn_ranges[0], &ndn->dn_ranges[0], sizeof (odn->dn_ranges));
ndn->dn_allocated_txg = odn->dn_allocated_txg;
ndn->dn_free_txg = odn->dn_free_txg;
ndn->dn_assigned_txg = odn->dn_assigned_txg;
ndn->dn_dirtyctx = odn->dn_dirtyctx;
ndn->dn_dirtyctx_firstset = odn->dn_dirtyctx_firstset;
ASSERT(refcount_count(&odn->dn_tx_holds) == 0);
refcount_transfer(&ndn->dn_holds, &odn->dn_holds);
ASSERT(list_is_empty(&ndn->dn_dbufs));
list_move_tail(&ndn->dn_dbufs, &odn->dn_dbufs);
ndn->dn_dbufs_count = odn->dn_dbufs_count;
ndn->dn_bonus = odn->dn_bonus;
ndn->dn_have_spill = odn->dn_have_spill;
ndn->dn_zio = odn->dn_zio;
ndn->dn_oldused = odn->dn_oldused;
ndn->dn_oldflags = odn->dn_oldflags;
ndn->dn_olduid = odn->dn_olduid;
ndn->dn_oldgid = odn->dn_oldgid;
ndn->dn_newuid = odn->dn_newuid;
ndn->dn_newgid = odn->dn_newgid;
ndn->dn_id_flags = odn->dn_id_flags;
dmu_zfetch_init(&ndn->dn_zfetch, NULL);
list_move_tail(&ndn->dn_zfetch.zf_stream, &odn->dn_zfetch.zf_stream);
ndn->dn_zfetch.zf_dnode = odn->dn_zfetch.zf_dnode;
ndn->dn_zfetch.zf_stream_cnt = odn->dn_zfetch.zf_stream_cnt;
ndn->dn_zfetch.zf_alloc_fail = odn->dn_zfetch.zf_alloc_fail;
/*
* Update back pointers. Updating the handle fixes the back pointer of
* every descendant dbuf as well as the bonus dbuf.
*/
ASSERT(ndn->dn_handle->dnh_dnode == odn);
ndn->dn_handle->dnh_dnode = ndn;
if (ndn->dn_zfetch.zf_dnode == odn) {
ndn->dn_zfetch.zf_dnode = ndn;
}
/*
* Invalidate the original dnode by clearing all of its back pointers.
*/
odn->dn_dbuf = NULL;
odn->dn_handle = NULL;
list_create(&odn->dn_dbufs, sizeof (dmu_buf_impl_t),
offsetof(dmu_buf_impl_t, db_link));
odn->dn_dbufs_count = 0;
odn->dn_bonus = NULL;
odn->dn_zfetch.zf_dnode = NULL;
/*
* Set the low bit of the objset pointer to ensure that dnode_move()
* recognizes the dnode as invalid in any subsequent callback.
*/
POINTER_INVALIDATE(&odn->dn_objset);
/*
* Satisfy the destructor.
*/
for (i = 0; i < TXG_SIZE; i++) {
list_create(&odn->dn_dirty_records[i],
sizeof (dbuf_dirty_record_t),
offsetof(dbuf_dirty_record_t, dr_dirty_node));
odn->dn_ranges[i].avl_root = NULL;
odn->dn_ranges[i].avl_numnodes = 0;
odn->dn_next_nlevels[i] = 0;
odn->dn_next_indblkshift[i] = 0;
odn->dn_next_bonustype[i] = 0;
odn->dn_rm_spillblk[i] = 0;
odn->dn_next_bonuslen[i] = 0;
odn->dn_next_blksz[i] = 0;
}
odn->dn_allocated_txg = 0;
odn->dn_free_txg = 0;
odn->dn_assigned_txg = 0;
odn->dn_dirtyctx = 0;
odn->dn_dirtyctx_firstset = NULL;
odn->dn_have_spill = B_FALSE;
odn->dn_zio = NULL;
odn->dn_oldused = 0;
odn->dn_oldflags = 0;
odn->dn_olduid = 0;
odn->dn_oldgid = 0;
odn->dn_newuid = 0;
odn->dn_newgid = 0;
odn->dn_id_flags = 0;
/*
* Mark the dnode.
*/
ndn->dn_moved = 1;
odn->dn_moved = (uint8_t)-1;
}
/*ARGSUSED*/
static kmem_cbrc_t
dnode_move(void *buf, void *newbuf, size_t size, void *arg)
{
dnode_t *odn = buf, *ndn = newbuf;
objset_t *os;
int64_t refcount;
uint32_t dbufs;
/*
* The dnode is on the objset's list of known dnodes if the objset
* pointer is valid. We set the low bit of the objset pointer when
* freeing the dnode to invalidate it, and the memory patterns written
* by kmem (baddcafe and deadbeef) set at least one of the two low bits.
* A newly created dnode sets the objset pointer last of all to indicate
* that the dnode is known and in a valid state to be moved by this
* function.
*/
os = odn->dn_objset;
if (!POINTER_IS_VALID(os)) {
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_invalid);
return (KMEM_CBRC_DONT_KNOW);
}
/*
* Ensure that the objset does not go away during the move.
*/
rw_enter(&os_lock, RW_WRITER);
if (os != odn->dn_objset) {
rw_exit(&os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_recheck1);
return (KMEM_CBRC_DONT_KNOW);
}
/*
* If the dnode is still valid, then so is the objset. We know that no
* valid objset can be freed while we hold os_lock, so we can safely
* ensure that the objset remains in use.
*/
mutex_enter(&os->os_lock);
/*
* Recheck the objset pointer in case the dnode was removed just before
* acquiring the lock.
*/
if (os != odn->dn_objset) {
mutex_exit(&os->os_lock);
rw_exit(&os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_recheck2);
return (KMEM_CBRC_DONT_KNOW);
}
/*
* At this point we know that as long as we hold os->os_lock, the dnode
* cannot be freed and fields within the dnode can be safely accessed.
* The objset listing this dnode cannot go away as long as this dnode is
* on its list.
*/
rw_exit(&os_lock);
if (DMU_OBJECT_IS_SPECIAL(odn->dn_object)) {
mutex_exit(&os->os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_special);
return (KMEM_CBRC_NO);
}
ASSERT(odn->dn_dbuf != NULL); /* only "special" dnodes have no parent */
/*
* Lock the dnode handle to prevent the dnode from obtaining any new
* holds. This also prevents the descendant dbufs and the bonus dbuf
* from accessing the dnode, so that we can discount their holds. The
* handle is safe to access because we know that while the dnode cannot
* go away, neither can its handle. Once we hold dnh_zrlock, we can
* safely move any dnode referenced only by dbufs.
*/
if (!zrl_tryenter(&odn->dn_handle->dnh_zrlock)) {
mutex_exit(&os->os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_handle);
return (KMEM_CBRC_LATER);
}
/*
* Ensure a consistent view of the dnode's holds and the dnode's dbufs.
* We need to guarantee that there is a hold for every dbuf in order to
* determine whether the dnode is actively referenced. Falsely matching
* a dbuf to an active hold would lead to an unsafe move. It's possible
* that a thread already having an active dnode hold is about to add a
* dbuf, and we can't compare hold and dbuf counts while the add is in
* progress.
*/
if (!rw_tryenter(&odn->dn_struct_rwlock, RW_WRITER)) {
zrl_exit(&odn->dn_handle->dnh_zrlock);
mutex_exit(&os->os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_rwlock);
return (KMEM_CBRC_LATER);
}
/*
* A dbuf may be removed (evicted) without an active dnode hold. In that
* case, the dbuf count is decremented under the handle lock before the
* dbuf's hold is released. This order ensures that if we count the hold
* after the dbuf is removed but before its hold is released, we will
* treat the unmatched hold as active and exit safely. If we count the
* hold before the dbuf is removed, the hold is discounted, and the
* removal is blocked until the move completes.
*/
refcount = refcount_count(&odn->dn_holds);
ASSERT(refcount >= 0);
dbufs = odn->dn_dbufs_count;
/* We can't have more dbufs than dnode holds. */
ASSERT3U(dbufs, <=, refcount);
DTRACE_PROBE3(dnode__move, dnode_t *, odn, int64_t, refcount,
uint32_t, dbufs);
if (refcount > dbufs) {
rw_exit(&odn->dn_struct_rwlock);
zrl_exit(&odn->dn_handle->dnh_zrlock);
mutex_exit(&os->os_lock);
DNODE_STAT_ADD(dnode_move_stats.dms_dnode_active);
return (KMEM_CBRC_LATER);
}
rw_exit(&odn->dn_struct_rwlock);
/*
* At this point we know that anyone with a hold on the dnode is not
* actively referencing it. The dnode is known and in a valid state to
* move. We're holding the locks needed to execute the critical section.
*/
dnode_move_impl(odn, ndn);
list_link_replace(&odn->dn_link, &ndn->dn_link);
/* If the dnode was safe to move, the refcount cannot have changed. */
ASSERT(refcount == refcount_count(&ndn->dn_holds));
ASSERT(dbufs == ndn->dn_dbufs_count);
zrl_exit(&ndn->dn_handle->dnh_zrlock); /* handle has moved */
mutex_exit(&os->os_lock);
return (KMEM_CBRC_YES);
}
#endif /* _KERNEL */
void
dnode_special_close(dnode_handle_t *dnh)
{
dnode_t *dn = dnh->dnh_dnode;
/*
* 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);
zrl_add(&dnh->dnh_zrlock);
dnode_destroy(dn); /* implicit zrl_remove() */
zrl_destroy(&dnh->dnh_zrlock);
dnh->dnh_dnode = NULL;
}
dnode_t *
dnode_special_open(objset_t *os, dnode_phys_t *dnp, uint64_t object,
dnode_handle_t *dnh)
{
dnode_t *dn = dnode_create(os, dnp, NULL, object, dnh);
dnh->dnh_dnode = dn;
zrl_init(&dnh->dnh_zrlock);
DNODE_VERIFY(dn);
return (dn);
}
static void
dnode_buf_pageout(dmu_buf_t *db, void *arg)
{
dnode_children_t *children_dnodes = arg;
int i;
int epb = db->db_size >> DNODE_SHIFT;
ASSERT(epb == children_dnodes->dnc_count);
for (i = 0; i < epb; i++) {
dnode_handle_t *dnh = &children_dnodes->dnc_children[i];
dnode_t *dn;
/*
* The dnode handle lock guards against the dnode moving to
* another valid address, so there is no need here to guard
* against changes to or from NULL.
*/
if (dnh->dnh_dnode == NULL) {
zrl_destroy(&dnh->dnh_zrlock);
continue;
}
zrl_add(&dnh->dnh_zrlock);
dn = dnh->dnh_dnode;
/*
* 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 eligible for eviction and this function
* would not have been called.
*/
ASSERT(refcount_is_zero(&dn->dn_holds));
ASSERT(refcount_is_zero(&dn->dn_tx_holds));
dnode_destroy(dn); /* implicit zrl_remove() */
zrl_destroy(&dnh->dnh_zrlock);
dnh->dnh_dnode = NULL;
}
kmem_free(children_dnodes, sizeof (dnode_children_t) +
(epb - 1) * sizeof (dnode_handle_t));
}
/*
* errors:
* EINVAL - invalid object number.
* EIO - i/o error.
* succeeds even for free dnodes.
*/
int
dnode_hold_impl(objset_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_children_t *children_dnodes;
dnode_handle_t *dnh;
/*
* If you are holding the spa config lock as writer, you shouldn't
* be asking the DMU to do *anything* unless it's the root pool
* which may require us to read from the root filesystem while
* holding some (not all) of the locks as writer.
*/
ASSERT(spa_config_held(os->os_spa, SCL_ALL, RW_WRITER) == 0 ||
(spa_is_root(os->os_spa) &&
spa_config_held(os->os_spa, SCL_STATE, RW_WRITER)));
if (object == DMU_USERUSED_OBJECT || object == DMU_GROUPUSED_OBJECT) {
dn = (object == DMU_USERUSED_OBJECT) ?
DMU_USERUSED_DNODE(os) : DMU_GROUPUSED_DNODE(os);
if (dn == NULL)
return (ENOENT);
type = dn->dn_type;
if ((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE)
return (ENOENT);
if ((flag & DNODE_MUST_BE_FREE) && type != DMU_OT_NONE)
return (EEXIST);
DNODE_VERIFY(dn);
(void) refcount_add(&dn->dn_holds, tag);
*dnp = dn;
return (0);
}
if (object == 0 || object >= DN_MAX_OBJECT)
return (EINVAL);
mdn = DMU_META_DNODE(os);
ASSERT(mdn->dn_object == DMU_META_DNODE_OBJECT);
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);
ASSERT(DB_DNODE(db)->dn_type == DMU_OT_DNODE);
children_dnodes = dmu_buf_get_user(&db->db);
if (children_dnodes == NULL) {
int i;
dnode_children_t *winner;
children_dnodes = kmem_alloc(sizeof (dnode_children_t) +
(epb - 1) * sizeof (dnode_handle_t),
KM_PUSHPAGE | KM_NODEBUG);
children_dnodes->dnc_count = epb;
dnh = &children_dnodes->dnc_children[0];
for (i = 0; i < epb; i++) {
zrl_init(&dnh[i].dnh_zrlock);
dnh[i].dnh_dnode = NULL;
}
if ((winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
dnode_buf_pageout))) {
kmem_free(children_dnodes, sizeof (dnode_children_t) +
(epb - 1) * sizeof (dnode_handle_t));
children_dnodes = winner;
}
}
ASSERT(children_dnodes->dnc_count == epb);
dnh = &children_dnodes->dnc_children[idx];
zrl_add(&dnh->dnh_zrlock);
if ((dn = dnh->dnh_dnode) == NULL) {
dnode_phys_t *phys = (dnode_phys_t *)db->db.db_data+idx;
dnode_t *winner;
dn = dnode_create(os, phys, db, object, dnh);
winner = atomic_cas_ptr(&dnh->dnh_dnode, NULL, dn);
if (winner != NULL) {
zrl_add(&dnh->dnh_zrlock);
dnode_destroy(dn); /* implicit zrl_remove() */
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 || !refcount_is_zero(&dn->dn_holds)))) {
mutex_exit(&dn->dn_mtx);
zrl_remove(&dnh->dnh_zrlock);
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, dnh);
/* Now we can rely on the hold to prevent the dnode from moving. */
zrl_remove(&dnh->dnh_zrlock);
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_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;
/* Get while the hold prevents the dnode from moving. */
dmu_buf_impl_t *db = dn->dn_dbuf;
dnode_handle_t *dnh = dn->dn_handle;
mutex_enter(&dn->dn_mtx);
refs = refcount_remove(&dn->dn_holds, tag);
mutex_exit(&dn->dn_mtx);
/*
* It's unsafe to release the last hold on a dnode by dnode_rele() or
* indirectly by dbuf_rele() while relying on the dnode handle to
* prevent the dnode from moving, since releasing the last hold could
* result in the dnode's parent dbuf evicting its dnode handles. For
* that reason anyone calling dnode_rele() or dbuf_rele() without some
* other direct or indirect hold on the dnode must first drop the dnode
* handle.
*/
ASSERT(refs > 0 || dnh->dnh_zrlock.zr_owner != curthread);
/* NOTE: the DNODE_DNODE does not have a dn_dbuf */
if (refs == 0 && db != NULL) {
/*
* Another thread could add a hold to the dnode handle in
* dnode_hold_impl() while holding the parent dbuf. Since the
* hold on the parent dbuf prevents the handle from being
* destroyed, the hold on the handle is OK. We can't yet assert
* that the handle has zero references, but that will be
* asserted anyway when the handle gets destroyed.
*/
dbuf_rele(db, dnh);
}
}
void
dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
{
objset_t *os = dn->dn_objset;
uint64_t txg = tx->tx_txg;
if (DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
dsl_dataset_dirty(os->os_dsl_dataset, tx);
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
/*
* Determine old uid/gid when necessary
*/
dmu_objset_userquota_get_ids(dn, B_TRUE, tx);
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);
ASSERT3U(dn->dn_next_bonustype[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 maintains 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 != DMU_BONUS_BLKID &&
db->db_blkid != DMU_SPILL_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 != DMU_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);
ASSERT(db != NULL);
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 != DMU_BONUS_BLKID &&
dr->dr_dbuf->db_blkid != DMU_SPILL_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);
}
static boolean_t
dnode_spill_freed(dnode_t *dn)
{
int i;
mutex_enter(&dn->dn_mtx);
for (i = 0; i < TXG_SIZE; i++) {
if (dn->dn_rm_spillblk[i] == DN_KILL_SPILLBLK)
break;
}
mutex_exit(&dn->dn_mtx);
return (i < TXG_SIZE);
}
/* 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 == DMU_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 (blkid == DMU_SPILL_BLKID)
return (dnode_spill_freed(dn));
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_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);
}
/*
* This function scans a block at the indicated "level" looking for
* a hole or data (depending on 'flags'). If level > 0, then we are
* scanning an indirect block looking at its pointers. If level == 0,
* then we are looking at a block of dnodes. If we don't find what we
* are looking for in the block, we return ESRCH. Otherwise, return
* with *offset pointing to the beginning (if searching forwards) or
* end (if searching backwards) of the range covered by the block
* pointer we matched on (or dnode).
*
* The basic search algorithm used below by dnode_next_offset() is to
* use this function to search up the block tree (widen the search) until
* we find something (i.e., we don't return ESRCH) and then search back
* down the tree (narrow the search) until we reach our original search
* level.
*/
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) != 0);
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) {
if ((dnp[i].dn_type == DMU_OT_NONE) == hole)
break;
*offset += (1ULL << span) * inc;
}
if (i < 0 || i == blkfill)
error = ESRCH;
} else {
blkptr_t *bp = data;
uint64_t start = *offset;
span = (lvl - 1) * epbs + dn->dn_datablkshift;
minfill = 0;
maxfill = blkfill << ((lvl - 1) * epbs);
if (hole)
maxfill--;
else
minfill++;
*offset = *offset >> span;
for (i = BF64_GET(*offset, 0, epbs);
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 > 0)
*offset += inc;
}
*offset = *offset << span;
if (inc < 0) {
/* traversing backwards; position offset at the end */
ASSERT3U(*offset, <=, start);
*offset = MIN(*offset + (1ULL << span) - 1, start);
} else if (*offset < start) {
*offset = start;
}
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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