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freebsd-dev/module/zfs/dmu_traverse.c
Matthew Ahrens d2d4f8554f
Fix prefetching of indirect blocks while destroying 
When traversing a tree of block pointers (e.g. for `zfs destroy <fs>` or
`zfs send`), we prefetch the indirect blocks that will be needed, in
`traverse_prefetch_metadata()`.  In the case of `zfs destroy <fs>`, we
do a little traversing each txg, and resume the traversal the next txg.
So the indirect blocks that will be needed, and thus are candidates for
prefetching, does not include blocks that are before the resume point.

The problem is that the logic for determining if the indirect blocks are
before the resume point is incorrect, causing the (up to 1024) L1
indirect blocks that are inside the first L2 to not be prefetched.  In
practice, if we are able to read many more than 1024 blocks per txg,
then this will be inconsequential.  But if i/o latency is more than a
few milliseconds, almost no L1's will be prefetched, so they will be
read serially, and thus the destroying will be very slow.  This can be
observed as `zpool get freeing` decreasing very slowly.

Specifically: When we first examine the L2 that contains the block we'll
be resuming from, we have not yet resumed, so `td_resume` is nonzero.
At this point, all calls to `traverse_prefetch_metadata()` will fail,
even if the L1 in question is after the resume point.  It isn't until
the callback is issued for the resume point that we zero out
`td_resume`, but by this point we've already attempted and failed to
prefetch everything under this L2 indirect block.

This commit addresses the issue by reusing the existing
`resume_skip_check()` to determine if the L1's bookmark is before or
after the resume point.  To do so, this function is made non-mutating
(the caller now zeros `td_resume`).

Note, this bug likely predates (was not introduced by) #11803.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #14603
2023-03-24 10:20:07 -07:00

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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 https://opensource.org/licenses/CDDL-1.0.
* 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.
* Copyright (c) 2012, 2018 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_traverse.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/dnode.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/dmu_impl.h>
#include <sys/sa.h>
#include <sys/sa_impl.h>
#include <sys/callb.h>
#include <sys/zfeature.h>
static int32_t zfs_pd_bytes_max = 50 * 1024 * 1024; /* 50MB */
static int32_t send_holes_without_birth_time = 1;
static uint_t zfs_traverse_indirect_prefetch_limit = 32;
typedef struct prefetch_data {
kmutex_t pd_mtx;
kcondvar_t pd_cv;
int32_t pd_bytes_fetched;
int pd_flags;
boolean_t pd_cancel;
boolean_t pd_exited;
zbookmark_phys_t pd_resume;
} prefetch_data_t;
typedef struct traverse_data {
spa_t *td_spa;
uint64_t td_objset;
blkptr_t *td_rootbp;
uint64_t td_min_txg;
zbookmark_phys_t *td_resume;
int td_flags;
prefetch_data_t *td_pfd;
boolean_t td_paused;
uint64_t td_hole_birth_enabled_txg;
blkptr_cb_t *td_func;
void *td_arg;
boolean_t td_realloc_possible;
} traverse_data_t;
static int traverse_dnode(traverse_data_t *td, const blkptr_t *bp,
const dnode_phys_t *dnp, uint64_t objset, uint64_t object);
static void prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *,
uint64_t objset, uint64_t object);
static int
traverse_zil_block(zilog_t *zilog, const blkptr_t *bp, void *arg,
uint64_t claim_txg)
{
traverse_data_t *td = arg;
zbookmark_phys_t zb;
if (BP_IS_HOLE(bp))
return (0);
if (claim_txg == 0 && bp->blk_birth >= spa_min_claim_txg(td->td_spa))
return (-1);
SET_BOOKMARK(&zb, td->td_objset, ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
(void) td->td_func(td->td_spa, zilog, bp, &zb, NULL, td->td_arg);
return (0);
}
static int
traverse_zil_record(zilog_t *zilog, const lr_t *lrc, void *arg,
uint64_t claim_txg)
{
traverse_data_t *td = arg;
if (lrc->lrc_txtype == TX_WRITE) {
lr_write_t *lr = (lr_write_t *)lrc;
blkptr_t *bp = &lr->lr_blkptr;
zbookmark_phys_t zb;
if (BP_IS_HOLE(bp))
return (0);
if (claim_txg == 0 || bp->blk_birth < claim_txg)
return (0);
ASSERT3U(BP_GET_LSIZE(bp), !=, 0);
SET_BOOKMARK(&zb, td->td_objset, lr->lr_foid,
ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp));
(void) td->td_func(td->td_spa, zilog, bp, &zb, NULL,
td->td_arg);
}
return (0);
}
static void
traverse_zil(traverse_data_t *td, zil_header_t *zh)
{
uint64_t claim_txg = zh->zh_claim_txg;
/*
* We only want to visit blocks that have been claimed but not yet
* replayed; plus blocks that are already stable in read-only mode.
*/
if (claim_txg == 0 && spa_writeable(td->td_spa))
return;
zilog_t *zilog = zil_alloc(spa_get_dsl(td->td_spa)->dp_meta_objset, zh);
(void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, td,
claim_txg, !(td->td_flags & TRAVERSE_NO_DECRYPT));
zil_free(zilog);
}
typedef enum resume_skip {
RESUME_SKIP_ALL,
RESUME_SKIP_NONE,
RESUME_SKIP_CHILDREN
} resume_skip_t;
/*
* Returns RESUME_SKIP_ALL if td indicates that we are resuming a traversal and
* the block indicated by zb does not need to be visited at all. Returns
* RESUME_SKIP_CHILDREN if we are resuming a post traversal and we reach the
* resume point. This indicates that this block should be visited but not its
* children (since they must have been visited in a previous traversal).
* Otherwise returns RESUME_SKIP_NONE.
*/
static resume_skip_t
resume_skip_check(const traverse_data_t *td, const dnode_phys_t *dnp,
const zbookmark_phys_t *zb)
{
if (td->td_resume != NULL) {
/*
* If we already visited this bp & everything below,
* don't bother doing it again.
*/
if (zbookmark_subtree_completed(dnp, zb, td->td_resume))
return (RESUME_SKIP_ALL);
if (memcmp(zb, td->td_resume, sizeof (*zb)) == 0) {
if (td->td_flags & TRAVERSE_POST)
return (RESUME_SKIP_CHILDREN);
}
}
return (RESUME_SKIP_NONE);
}
/*
* Returns B_TRUE, if prefetch read is issued, otherwise B_FALSE.
*/
static boolean_t
traverse_prefetch_metadata(traverse_data_t *td, const dnode_phys_t *dnp,
const blkptr_t *bp, const zbookmark_phys_t *zb)
{
arc_flags_t flags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH |
ARC_FLAG_PRESCIENT_PREFETCH;
int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE;
if (!(td->td_flags & TRAVERSE_PREFETCH_METADATA))
return (B_FALSE);
/*
* If this bp is before the resume point, it may have already been
* freed.
*/
if (resume_skip_check(td, dnp, zb) != RESUME_SKIP_NONE)
return (B_FALSE);
if (BP_IS_HOLE(bp) || bp->blk_birth <= td->td_min_txg)
return (B_FALSE);
if (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE)
return (B_FALSE);
ASSERT(!BP_IS_REDACTED(bp));
if ((td->td_flags & TRAVERSE_NO_DECRYPT) && BP_IS_PROTECTED(bp))
zio_flags |= ZIO_FLAG_RAW;
(void) arc_read(NULL, td->td_spa, bp, NULL, NULL,
ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
return (B_TRUE);
}
static boolean_t
prefetch_needed(prefetch_data_t *pfd, const blkptr_t *bp)
{
ASSERT(pfd->pd_flags & TRAVERSE_PREFETCH_DATA);
if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp) ||
BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG || BP_IS_REDACTED(bp))
return (B_FALSE);
return (B_TRUE);
}
static int
traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
const blkptr_t *bp, const zbookmark_phys_t *zb)
{
int err = 0;
arc_buf_t *buf = NULL;
prefetch_data_t *pd = td->td_pfd;
switch (resume_skip_check(td, dnp, zb)) {
case RESUME_SKIP_ALL:
return (0);
case RESUME_SKIP_CHILDREN:
goto post;
case RESUME_SKIP_NONE:
break;
default:
ASSERT(0);
}
if (bp->blk_birth == 0) {
/*
* Since this block has a birth time of 0 it must be one of
* two things: a hole created before the
* SPA_FEATURE_HOLE_BIRTH feature was enabled, or a hole
* which has always been a hole in an object.
*
* If a file is written sparsely, then the unwritten parts of
* the file were "always holes" -- that is, they have been
* holes since this object was allocated. However, we (and
* our callers) can not necessarily tell when an object was
* allocated. Therefore, if it's possible that this object
* was freed and then its object number reused, we need to
* visit all the holes with birth==0.
*
* If it isn't possible that the object number was reused,
* then if SPA_FEATURE_HOLE_BIRTH was enabled before we wrote
* all the blocks we will visit as part of this traversal,
* then this hole must have always existed, so we can skip
* it. We visit blocks born after (exclusive) td_min_txg.
*
* Note that the meta-dnode cannot be reallocated.
*/
if (!send_holes_without_birth_time &&
(!td->td_realloc_possible ||
zb->zb_object == DMU_META_DNODE_OBJECT) &&
td->td_hole_birth_enabled_txg <= td->td_min_txg)
return (0);
} else if (bp->blk_birth <= td->td_min_txg) {
return (0);
}
if (pd != NULL && !pd->pd_exited && prefetch_needed(pd, bp)) {
uint64_t size = BP_GET_LSIZE(bp);
mutex_enter(&pd->pd_mtx);
ASSERT(pd->pd_bytes_fetched >= 0);
while (pd->pd_bytes_fetched < size && !pd->pd_exited)
cv_wait_sig(&pd->pd_cv, &pd->pd_mtx);
pd->pd_bytes_fetched -= size;
cv_broadcast(&pd->pd_cv);
mutex_exit(&pd->pd_mtx);
}
if (BP_IS_HOLE(bp) || BP_IS_REDACTED(bp)) {
err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
if (err != 0)
goto post;
return (0);
}
if (td->td_flags & TRAVERSE_PRE) {
err = td->td_func(td->td_spa, NULL, bp, zb, dnp,
td->td_arg);
if (err == TRAVERSE_VISIT_NO_CHILDREN)
return (0);
if (err != 0)
goto post;
}
if (BP_GET_LEVEL(bp) > 0) {
uint32_t flags = ARC_FLAG_WAIT;
int32_t i, ptidx, pidx;
uint32_t prefetchlimit;
int32_t epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
zbookmark_phys_t *czb;
ASSERT(!BP_IS_PROTECTED(bp));
err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
if (err != 0)
goto post;
czb = kmem_alloc(sizeof (zbookmark_phys_t), KM_SLEEP);
/*
* When performing a traversal it is beneficial to
* asynchronously read-ahead the upcoming indirect
* blocks since they will be needed shortly. However,
* since a 128k indirect (non-L0) block may contain up
* to 1024 128-byte block pointers, its preferable to not
* prefetch them all at once. Issuing a large number of
* async reads may effect performance, and the earlier
* the indirect blocks are prefetched the less likely
* they are to still be resident in the ARC when needed.
* Therefore, prefetching indirect blocks is limited to
* zfs_traverse_indirect_prefetch_limit=32 blocks by
* default.
*
* pidx: Index for which next prefetch to be issued.
* ptidx: Index at which next prefetch to be triggered.
*/
ptidx = 0;
pidx = 1;
prefetchlimit = zfs_traverse_indirect_prefetch_limit;
for (i = 0; i < epb; i++) {
if (prefetchlimit && i == ptidx) {
ASSERT3S(ptidx, <=, pidx);
for (uint32_t prefetched = 0; pidx < epb &&
prefetched < prefetchlimit; pidx++) {
SET_BOOKMARK(czb, zb->zb_objset,
zb->zb_object, zb->zb_level - 1,
zb->zb_blkid * epb + pidx);
if (traverse_prefetch_metadata(td, dnp,
&((blkptr_t *)buf->b_data)[pidx],
czb) == B_TRUE) {
prefetched++;
if (prefetched ==
MAX(prefetchlimit / 2, 1))
ptidx = pidx;
}
}
}
/* recursively visitbp() blocks below this */
SET_BOOKMARK(czb, zb->zb_objset, zb->zb_object,
zb->zb_level - 1,
zb->zb_blkid * epb + i);
err = traverse_visitbp(td, dnp,
&((blkptr_t *)buf->b_data)[i], czb);
if (err != 0)
break;
}
kmem_free(czb, sizeof (zbookmark_phys_t));
} else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
uint32_t flags = ARC_FLAG_WAIT;
uint32_t zio_flags = ZIO_FLAG_CANFAIL;
int32_t i;
int32_t epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
dnode_phys_t *child_dnp;
/*
* dnode blocks might have their bonus buffers encrypted, so
* we must be careful to honor TRAVERSE_NO_DECRYPT
*/
if ((td->td_flags & TRAVERSE_NO_DECRYPT) && BP_IS_PROTECTED(bp))
zio_flags |= ZIO_FLAG_RAW;
err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
if (err != 0)
goto post;
child_dnp = buf->b_data;
for (i = 0; i < epb; i += child_dnp[i].dn_extra_slots + 1) {
prefetch_dnode_metadata(td, &child_dnp[i],
zb->zb_objset, zb->zb_blkid * epb + i);
}
/* recursively visitbp() blocks below this */
for (i = 0; i < epb; i += child_dnp[i].dn_extra_slots + 1) {
err = traverse_dnode(td, bp, &child_dnp[i],
zb->zb_objset, zb->zb_blkid * epb + i);
if (err != 0)
break;
}
} else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
uint32_t zio_flags = ZIO_FLAG_CANFAIL;
arc_flags_t flags = ARC_FLAG_WAIT;
objset_phys_t *osp;
if ((td->td_flags & TRAVERSE_NO_DECRYPT) && BP_IS_PROTECTED(bp))
zio_flags |= ZIO_FLAG_RAW;
err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
if (err != 0)
goto post;
osp = buf->b_data;
prefetch_dnode_metadata(td, &osp->os_meta_dnode, zb->zb_objset,
DMU_META_DNODE_OBJECT);
/*
* See the block comment above for the goal of this variable.
* If the maxblkid of the meta-dnode is 0, then we know that
* we've never had more than DNODES_PER_BLOCK objects in the
* dataset, which means we can't have reused any object ids.
*/
if (osp->os_meta_dnode.dn_maxblkid == 0)
td->td_realloc_possible = B_FALSE;
if (OBJSET_BUF_HAS_USERUSED(buf)) {
if (OBJSET_BUF_HAS_PROJECTUSED(buf))
prefetch_dnode_metadata(td,
&osp->os_projectused_dnode,
zb->zb_objset, DMU_PROJECTUSED_OBJECT);
prefetch_dnode_metadata(td, &osp->os_groupused_dnode,
zb->zb_objset, DMU_GROUPUSED_OBJECT);
prefetch_dnode_metadata(td, &osp->os_userused_dnode,
zb->zb_objset, DMU_USERUSED_OBJECT);
}
err = traverse_dnode(td, bp, &osp->os_meta_dnode, zb->zb_objset,
DMU_META_DNODE_OBJECT);
if (err == 0 && OBJSET_BUF_HAS_USERUSED(buf)) {
if (OBJSET_BUF_HAS_PROJECTUSED(buf))
err = traverse_dnode(td, bp,
&osp->os_projectused_dnode, zb->zb_objset,
DMU_PROJECTUSED_OBJECT);
if (err == 0)
err = traverse_dnode(td, bp,
&osp->os_groupused_dnode, zb->zb_objset,
DMU_GROUPUSED_OBJECT);
if (err == 0)
err = traverse_dnode(td, bp,
&osp->os_userused_dnode, zb->zb_objset,
DMU_USERUSED_OBJECT);
}
}
if (buf)
arc_buf_destroy(buf, &buf);
post:
if (err == 0 && (td->td_flags & TRAVERSE_POST))
err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
if ((td->td_flags & TRAVERSE_HARD) && (err == EIO || err == ECKSUM)) {
/*
* Ignore this disk error as requested by the HARD flag,
* and continue traversal.
*/
err = 0;
}
/*
* If we are stopping here, set td_resume.
*/
if (td->td_resume != NULL && err != 0 && !td->td_paused) {
td->td_resume->zb_objset = zb->zb_objset;
td->td_resume->zb_object = zb->zb_object;
td->td_resume->zb_level = 0;
/*
* If we have stopped on an indirect block (e.g. due to
* i/o error), we have not visited anything below it.
* Set the bookmark to the first level-0 block that we need
* to visit. This way, the resuming code does not need to
* deal with resuming from indirect blocks.
*
* Note, if zb_level <= 0, dnp may be NULL, so we don't want
* to dereference it.
*/
td->td_resume->zb_blkid = zb->zb_blkid;
if (zb->zb_level > 0) {
td->td_resume->zb_blkid <<= zb->zb_level *
(dnp->dn_indblkshift - SPA_BLKPTRSHIFT);
}
td->td_paused = B_TRUE;
}
return (err);
}
static void
prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *dnp,
uint64_t objset, uint64_t object)
{
int j;
zbookmark_phys_t czb;
for (j = 0; j < dnp->dn_nblkptr; j++) {
SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
traverse_prefetch_metadata(td, dnp, &dnp->dn_blkptr[j], &czb);
}
if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
traverse_prefetch_metadata(td, dnp, DN_SPILL_BLKPTR(dnp), &czb);
}
}
static int
traverse_dnode(traverse_data_t *td, const blkptr_t *bp, const dnode_phys_t *dnp,
uint64_t objset, uint64_t object)
{
int j, err = 0;
zbookmark_phys_t czb;
if (object != DMU_META_DNODE_OBJECT && td->td_resume != NULL &&
object < td->td_resume->zb_object)
return (0);
if (td->td_flags & TRAVERSE_PRE) {
SET_BOOKMARK(&czb, objset, object, ZB_DNODE_LEVEL,
ZB_DNODE_BLKID);
err = td->td_func(td->td_spa, NULL, bp, &czb, dnp,
td->td_arg);
if (err == TRAVERSE_VISIT_NO_CHILDREN)
return (0);
if (err != 0)
return (err);
}
for (j = 0; j < dnp->dn_nblkptr; j++) {
SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
err = traverse_visitbp(td, dnp, &dnp->dn_blkptr[j], &czb);
if (err != 0)
break;
}
if (err == 0 && (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) {
SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
err = traverse_visitbp(td, dnp, DN_SPILL_BLKPTR(dnp), &czb);
}
if (err == 0 && (td->td_flags & TRAVERSE_POST)) {
SET_BOOKMARK(&czb, objset, object, ZB_DNODE_LEVEL,
ZB_DNODE_BLKID);
err = td->td_func(td->td_spa, NULL, bp, &czb, dnp,
td->td_arg);
if (err == TRAVERSE_VISIT_NO_CHILDREN)
return (0);
if (err != 0)
return (err);
}
return (err);
}
static int
traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
{
(void) zilog, (void) dnp;
prefetch_data_t *pfd = arg;
int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE;
arc_flags_t aflags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH |
ARC_FLAG_PRESCIENT_PREFETCH;
ASSERT(pfd->pd_bytes_fetched >= 0);
if (zb->zb_level == ZB_DNODE_LEVEL)
return (0);
if (pfd->pd_cancel)
return (SET_ERROR(EINTR));
if (!prefetch_needed(pfd, bp))
return (0);
mutex_enter(&pfd->pd_mtx);
while (!pfd->pd_cancel && pfd->pd_bytes_fetched >= zfs_pd_bytes_max)
cv_wait_sig(&pfd->pd_cv, &pfd->pd_mtx);
pfd->pd_bytes_fetched += BP_GET_LSIZE(bp);
cv_broadcast(&pfd->pd_cv);
mutex_exit(&pfd->pd_mtx);
if ((pfd->pd_flags & TRAVERSE_NO_DECRYPT) && BP_IS_PROTECTED(bp))
zio_flags |= ZIO_FLAG_RAW;
(void) arc_read(NULL, spa, bp, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
zio_flags, &aflags, zb);
return (0);
}
static void
traverse_prefetch_thread(void *arg)
{
traverse_data_t *td_main = arg;
traverse_data_t td = *td_main;
zbookmark_phys_t czb;
fstrans_cookie_t cookie = spl_fstrans_mark();
td.td_func = traverse_prefetcher;
td.td_arg = td_main->td_pfd;
td.td_pfd = NULL;
td.td_resume = &td_main->td_pfd->pd_resume;
SET_BOOKMARK(&czb, td.td_objset,
ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
(void) traverse_visitbp(&td, NULL, td.td_rootbp, &czb);
mutex_enter(&td_main->td_pfd->pd_mtx);
td_main->td_pfd->pd_exited = B_TRUE;
cv_broadcast(&td_main->td_pfd->pd_cv);
mutex_exit(&td_main->td_pfd->pd_mtx);
spl_fstrans_unmark(cookie);
}
/*
* NB: dataset must not be changing on-disk (eg, is a snapshot or we are
* in syncing context).
*/
static int
traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
uint64_t txg_start, zbookmark_phys_t *resume, int flags,
blkptr_cb_t func, void *arg)
{
traverse_data_t *td;
prefetch_data_t *pd;
zbookmark_phys_t *czb;
int err;
ASSERT(ds == NULL || objset == ds->ds_object);
ASSERT(!(flags & TRAVERSE_PRE) || !(flags & TRAVERSE_POST));
td = kmem_alloc(sizeof (traverse_data_t), KM_SLEEP);
pd = kmem_zalloc(sizeof (prefetch_data_t), KM_SLEEP);
czb = kmem_alloc(sizeof (zbookmark_phys_t), KM_SLEEP);
td->td_spa = spa;
td->td_objset = objset;
td->td_rootbp = rootbp;
td->td_min_txg = txg_start;
td->td_resume = resume;
td->td_func = func;
td->td_arg = arg;
td->td_pfd = pd;
td->td_flags = flags;
td->td_paused = B_FALSE;
td->td_realloc_possible = (txg_start == 0 ? B_FALSE : B_TRUE);
if (spa_feature_is_active(spa, SPA_FEATURE_HOLE_BIRTH)) {
VERIFY(spa_feature_enabled_txg(spa,
SPA_FEATURE_HOLE_BIRTH, &td->td_hole_birth_enabled_txg));
} else {
td->td_hole_birth_enabled_txg = UINT64_MAX;
}
pd->pd_flags = flags;
if (resume != NULL)
pd->pd_resume = *resume;
mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);
SET_BOOKMARK(czb, td->td_objset,
ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
/* See comment on ZIL traversal in dsl_scan_visitds. */
if (ds != NULL && !ds->ds_is_snapshot && !BP_IS_HOLE(rootbp)) {
zio_flag_t zio_flags = ZIO_FLAG_CANFAIL;
uint32_t flags = ARC_FLAG_WAIT;
objset_phys_t *osp;
arc_buf_t *buf;
ASSERT(!BP_IS_REDACTED(rootbp));
if ((td->td_flags & TRAVERSE_NO_DECRYPT) &&
BP_IS_PROTECTED(rootbp))
zio_flags |= ZIO_FLAG_RAW;
err = arc_read(NULL, td->td_spa, rootbp, arc_getbuf_func,
&buf, ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, czb);
if (err != 0) {
/*
* If both TRAVERSE_HARD and TRAVERSE_PRE are set,
* continue to visitbp so that td_func can be called
* in pre stage, and err will reset to zero.
*/
if (!(td->td_flags & TRAVERSE_HARD) ||
!(td->td_flags & TRAVERSE_PRE))
goto out;
} else {
osp = buf->b_data;
traverse_zil(td, &osp->os_zil_header);
arc_buf_destroy(buf, &buf);
}
}
if (!(flags & TRAVERSE_PREFETCH_DATA) ||
taskq_dispatch(spa->spa_prefetch_taskq, traverse_prefetch_thread,
td, TQ_NOQUEUE) == TASKQID_INVALID)
pd->pd_exited = B_TRUE;
err = traverse_visitbp(td, NULL, rootbp, czb);
mutex_enter(&pd->pd_mtx);
pd->pd_cancel = B_TRUE;
cv_broadcast(&pd->pd_cv);
while (!pd->pd_exited)
cv_wait_sig(&pd->pd_cv, &pd->pd_mtx);
mutex_exit(&pd->pd_mtx);
out:
mutex_destroy(&pd->pd_mtx);
cv_destroy(&pd->pd_cv);
kmem_free(czb, sizeof (zbookmark_phys_t));
kmem_free(pd, sizeof (struct prefetch_data));
kmem_free(td, sizeof (struct traverse_data));
return (err);
}
/*
* NB: dataset must not be changing on-disk (eg, is a snapshot or we are
* in syncing context).
*/
int
traverse_dataset_resume(dsl_dataset_t *ds, uint64_t txg_start,
zbookmark_phys_t *resume,
int flags, blkptr_cb_t func, void *arg)
{
return (traverse_impl(ds->ds_dir->dd_pool->dp_spa, ds, ds->ds_object,
&dsl_dataset_phys(ds)->ds_bp, txg_start, resume, flags, func, arg));
}
int
traverse_dataset(dsl_dataset_t *ds, uint64_t txg_start,
int flags, blkptr_cb_t func, void *arg)
{
return (traverse_dataset_resume(ds, txg_start, NULL, flags, func, arg));
}
int
traverse_dataset_destroyed(spa_t *spa, blkptr_t *blkptr,
uint64_t txg_start, zbookmark_phys_t *resume, int flags,
blkptr_cb_t func, void *arg)
{
return (traverse_impl(spa, NULL, ZB_DESTROYED_OBJSET,
blkptr, txg_start, resume, flags, func, arg));
}
/*
* NB: pool must not be changing on-disk (eg, from zdb or sync context).
*/
int
traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
blkptr_cb_t func, void *arg)
{
int err;
dsl_pool_t *dp = spa_get_dsl(spa);
objset_t *mos = dp->dp_meta_objset;
boolean_t hard = (flags & TRAVERSE_HARD);
/* visit the MOS */
err = traverse_impl(spa, NULL, 0, spa_get_rootblkptr(spa),
txg_start, NULL, flags, func, arg);
if (err != 0)
return (err);
/* visit each dataset */
for (uint64_t obj = 1; err == 0;
err = dmu_object_next(mos, &obj, B_FALSE, txg_start)) {
dmu_object_info_t doi;
err = dmu_object_info(mos, obj, &doi);
if (err != 0) {
if (hard)
continue;
break;
}
if (doi.doi_bonus_type == DMU_OT_DSL_DATASET) {
dsl_dataset_t *ds;
uint64_t txg = txg_start;
dsl_pool_config_enter(dp, FTAG);
err = dsl_dataset_hold_obj(dp, obj, FTAG, &ds);
dsl_pool_config_exit(dp, FTAG);
if (err != 0) {
if (hard)
continue;
break;
}
if (dsl_dataset_phys(ds)->ds_prev_snap_txg > txg)
txg = dsl_dataset_phys(ds)->ds_prev_snap_txg;
err = traverse_dataset(ds, txg, flags, func, arg);
dsl_dataset_rele(ds, FTAG);
if (err != 0)
break;
}
}
if (err == ESRCH)
err = 0;
return (err);
}
EXPORT_SYMBOL(traverse_dataset);
EXPORT_SYMBOL(traverse_pool);
ZFS_MODULE_PARAM(zfs, zfs_, pd_bytes_max, INT, ZMOD_RW,
"Max number of bytes to prefetch");
ZFS_MODULE_PARAM(zfs, zfs_, traverse_indirect_prefetch_limit, UINT, ZMOD_RW,
"Traverse prefetch number of blocks pointed by indirect block");
#if defined(_KERNEL)
module_param_named(ignore_hole_birth, send_holes_without_birth_time, int, 0644);
MODULE_PARM_DESC(ignore_hole_birth,
"Alias for send_holes_without_birth_time");
#endif
/* CSTYLED */
ZFS_MODULE_PARAM(zfs, , send_holes_without_birth_time, INT, ZMOD_RW,
"Ignore hole_birth txg for zfs send");
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