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mirror_zfs/module/zfs/dmu_object.c
Richard Yao fdc2d30371
Cleanup: Specify unsignedness on things that should not be signed 
In #13871, zfs_vdev_aggregation_limit_non_rotating and
zfs_vdev_aggregation_limit being signed was pointed out as a possible
reason not to eliminate an unnecessary MAX(unsigned, 0) since the
unsigned value was assigned from them.

There is no reason for these module parameters to be signed and upon
inspection, it was found that there are a number of other module
parameters that are signed, but should not be, so we make them unsigned.
Making them unsigned made it clear that some other variables in the code
should also be unsigned, so we also make those unsigned. This prevents
users from setting negative values that could potentially cause bad
behaviors. It also makes the code slightly easier to understand.

Mostly module parameters that deal with timeouts, limits, bitshifts and
percentages are made unsigned by this. Any that are boolean are left
signed, since whether booleans should be considered signed or unsigned
does not matter.

Making zfs_arc_lotsfree_percent unsigned caused a
`zfs_arc_lotsfree_percent >= 0` check to become redundant, so it was
removed. Removing the check was also necessary to prevent a compiler
error from -Werror=type-limits.

Several end of line comments had to be moved to their own lines because
replacing int with uint_t caused us to exceed the 80 character limit
enforced by cstyle.pl.

The following were kept signed because they are passed to
taskq_create(), which expects signed values and modifying the
OpenSolaris/Illumos DDI is out of scope of this patch:

	* metaslab_load_pct
	* zfs_sync_taskq_batch_pct
	* zfs_zil_clean_taskq_nthr_pct
	* zfs_zil_clean_taskq_minalloc
	* zfs_zil_clean_taskq_maxalloc
	* zfs_arc_prune_task_threads

Also, negative values in those parameters was found to be harmless.

The following were left signed because either negative values make
sense, or more analysis was needed to determine whether negative values
should be disallowed:

	* zfs_metaslab_switch_threshold
	* zfs_pd_bytes_max
	* zfs_livelist_min_percent_shared

zfs_multihost_history was made static to be consistent with other
parameters.

A number of module parameters were marked as signed, but in reality
referenced unsigned variables. upgrade_errlog_limit is one of the
numerous examples. In the case of zfs_vdev_async_read_max_active, it was
already uint32_t, but zdb had an extern int declaration for it.

Interestingly, the documentation in zfs.4 was right for
upgrade_errlog_limit despite the module parameter being wrongly marked,
while the documentation for zfs_vdev_async_read_max_active (and friends)
was wrong. It was also wrong for zstd_abort_size, which was unsigned,
but was documented as signed.

Also, the documentation in zfs.4 incorrectly described the following
parameters as ulong when they were int:

	* zfs_arc_meta_adjust_restarts
	* zfs_override_estimate_recordsize

They are now uint_t as of this patch and thus the man page has been
updated to describe them as uint.

dbuf_state_index was left alone since it does nothing and perhaps should
be removed in another patch.

If any module parameters were missed, they were not found by `grep -r
'ZFS_MODULE_PARAM' | grep ', INT'`. I did find a few that grep missed,
but only because they were in files that had hits.

This patch intentionally did not attempt to address whether some of
these module parameters should be elevated to 64-bit parameters, because
the length of a long on 32-bit is 32-bit.

Lastly, it was pointed out during review that uint_t is a better match
for these variables than uint32_t because FreeBSD kernel parameter
definitions are designed for uint_t, whose bit width can change in
future memory models.  As a result, we change the existing parameters
that are uint32_t to use uint_t.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Neal Gompa <ngompa@datto.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13875
2022-09-27 16:42:41 -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) 2013, 2017 by Delphix. All rights reserved.
* Copyright 2014 HybridCluster. All rights reserved.
*/
#include <sys/dbuf.h>
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_tx.h>
#include <sys/dnode.h>
#include <sys/zap.h>
#include <sys/zfeature.h>
#include <sys/dsl_dataset.h>
/*
* Each of the concurrent object allocators will grab
* 2^dmu_object_alloc_chunk_shift dnode slots at a time. The default is to
* grab 128 slots, which is 4 blocks worth. This was experimentally
* determined to be the lowest value that eliminates the measurable effect
* of lock contention from this code path.
*/
uint_t dmu_object_alloc_chunk_shift = 7;
static uint64_t
dmu_object_alloc_impl(objset_t *os, dmu_object_type_t ot, int blocksize,
int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
int dnodesize, dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
{
uint64_t object;
uint64_t L1_dnode_count = DNODES_PER_BLOCK <<
(DMU_META_DNODE(os)->dn_indblkshift - SPA_BLKPTRSHIFT);
dnode_t *dn = NULL;
int dn_slots = dnodesize >> DNODE_SHIFT;
boolean_t restarted = B_FALSE;
uint64_t *cpuobj = NULL;
uint_t dnodes_per_chunk = 1 << dmu_object_alloc_chunk_shift;
int error;
cpuobj = &os->os_obj_next_percpu[CPU_SEQID_UNSTABLE %
os->os_obj_next_percpu_len];
if (dn_slots == 0) {
dn_slots = DNODE_MIN_SLOTS;
} else {
ASSERT3S(dn_slots, >=, DNODE_MIN_SLOTS);
ASSERT3S(dn_slots, <=, DNODE_MAX_SLOTS);
}
/*
* The "chunk" of dnodes that is assigned to a CPU-specific
* allocator needs to be at least one block's worth, to avoid
* lock contention on the dbuf. It can be at most one L1 block's
* worth, so that the "rescan after polishing off a L1's worth"
* logic below will be sure to kick in.
*/
if (dnodes_per_chunk < DNODES_PER_BLOCK)
dnodes_per_chunk = DNODES_PER_BLOCK;
if (dnodes_per_chunk > L1_dnode_count)
dnodes_per_chunk = L1_dnode_count;
/*
* The caller requested the dnode be returned as a performance
* optimization in order to avoid releasing the hold only to
* immediately reacquire it. Since they caller is responsible
* for releasing the hold they must provide the tag.
*/
if (allocated_dnode != NULL) {
ASSERT3P(tag, !=, NULL);
} else {
ASSERT3P(tag, ==, NULL);
tag = FTAG;
}
object = *cpuobj;
for (;;) {
/*
* If we finished a chunk of dnodes, get a new one from
* the global allocator.
*/
if ((P2PHASE(object, dnodes_per_chunk) == 0) ||
(P2PHASE(object + dn_slots - 1, dnodes_per_chunk) <
dn_slots)) {
DNODE_STAT_BUMP(dnode_alloc_next_chunk);
mutex_enter(&os->os_obj_lock);
ASSERT0(P2PHASE(os->os_obj_next_chunk,
dnodes_per_chunk));
object = os->os_obj_next_chunk;
/*
* Each time we polish off a L1 bp worth of dnodes
* (2^12 objects), move to another L1 bp that's
* still reasonably sparse (at most 1/4 full). Look
* from the beginning at most once per txg. If we
* still can't allocate from that L1 block, search
* for an empty L0 block, which will quickly skip
* to the end of the metadnode if no nearby L0
* blocks are empty. This fallback avoids a
* pathology where full dnode blocks containing
* large dnodes appear sparse because they have a
* low blk_fill, leading to many failed allocation
* attempts. In the long term a better mechanism to
* search for sparse metadnode regions, such as
* spacemaps, could be implemented.
*
* os_scan_dnodes is set during txg sync if enough
* objects have been freed since the previous
* rescan to justify backfilling again.
*
* Note that dmu_traverse depends on the behavior
* that we use multiple blocks of the dnode object
* before going back to reuse objects. Any change
* to this algorithm should preserve that property
* or find another solution to the issues described
* in traverse_visitbp.
*/
if (P2PHASE(object, L1_dnode_count) == 0) {
uint64_t offset;
uint64_t blkfill;
int minlvl;
if (os->os_rescan_dnodes) {
offset = 0;
os->os_rescan_dnodes = B_FALSE;
} else {
offset = object << DNODE_SHIFT;
}
blkfill = restarted ? 1 : DNODES_PER_BLOCK >> 2;
minlvl = restarted ? 1 : 2;
restarted = B_TRUE;
error = dnode_next_offset(DMU_META_DNODE(os),
DNODE_FIND_HOLE, &offset, minlvl,
blkfill, 0);
if (error == 0) {
object = offset >> DNODE_SHIFT;
}
}
/*
* Note: if "restarted", we may find a L0 that
* is not suitably aligned.
*/
os->os_obj_next_chunk =
P2ALIGN(object, dnodes_per_chunk) +
dnodes_per_chunk;
(void) atomic_swap_64(cpuobj, object);
mutex_exit(&os->os_obj_lock);
}
/*
* The value of (*cpuobj) before adding dn_slots is the object
* ID assigned to us. The value afterwards is the object ID
* assigned to whoever wants to do an allocation next.
*/
object = atomic_add_64_nv(cpuobj, dn_slots) - dn_slots;
/*
* XXX We should check for an i/o error here and return
* up to our caller. Actually we should pre-read it in
* dmu_tx_assign(), but there is currently no mechanism
* to do so.
*/
error = dnode_hold_impl(os, object, DNODE_MUST_BE_FREE,
dn_slots, tag, &dn);
if (error == 0) {
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
/*
* Another thread could have allocated it; check
* again now that we have the struct lock.
*/
if (dn->dn_type == DMU_OT_NONE) {
dnode_allocate(dn, ot, blocksize,
indirect_blockshift, bonustype,
bonuslen, dn_slots, tx);
rw_exit(&dn->dn_struct_rwlock);
dmu_tx_add_new_object(tx, dn);
/*
* Caller requested the allocated dnode be
* returned and is responsible for the hold.
*/
if (allocated_dnode != NULL)
*allocated_dnode = dn;
else
dnode_rele(dn, tag);
return (object);
}
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, tag);
DNODE_STAT_BUMP(dnode_alloc_race);
}
/*
* Skip to next known valid starting point on error. This
* is the start of the next block of dnodes.
*/
if (dmu_object_next(os, &object, B_TRUE, 0) != 0) {
object = P2ROUNDUP(object + 1, DNODES_PER_BLOCK);
DNODE_STAT_BUMP(dnode_alloc_next_block);
}
(void) atomic_swap_64(cpuobj, object);
}
}
uint64_t
dmu_object_alloc(objset_t *os, dmu_object_type_t ot, int blocksize,
dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
return dmu_object_alloc_impl(os, ot, blocksize, 0, bonustype,
bonuslen, 0, NULL, NULL, tx);
}
uint64_t
dmu_object_alloc_ibs(objset_t *os, dmu_object_type_t ot, int blocksize,
int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
dmu_tx_t *tx)
{
return dmu_object_alloc_impl(os, ot, blocksize, indirect_blockshift,
bonustype, bonuslen, 0, NULL, NULL, tx);
}
uint64_t
dmu_object_alloc_dnsize(objset_t *os, dmu_object_type_t ot, int blocksize,
dmu_object_type_t bonustype, int bonuslen, int dnodesize, dmu_tx_t *tx)
{
return (dmu_object_alloc_impl(os, ot, blocksize, 0, bonustype,
bonuslen, dnodesize, NULL, NULL, tx));
}
/*
* Allocate a new object and return a pointer to the newly allocated dnode
* via the allocated_dnode argument. The returned dnode will be held and
* the caller is responsible for releasing the hold by calling dnode_rele().
*/
uint64_t
dmu_object_alloc_hold(objset_t *os, dmu_object_type_t ot, int blocksize,
int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
int dnodesize, dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
{
return (dmu_object_alloc_impl(os, ot, blocksize, indirect_blockshift,
bonustype, bonuslen, dnodesize, allocated_dnode, tag, tx));
}
int
dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
return (dmu_object_claim_dnsize(os, object, ot, blocksize, bonustype,
bonuslen, 0, tx));
}
int
dmu_object_claim_dnsize(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonustype, int bonuslen,
int dnodesize, dmu_tx_t *tx)
{
dnode_t *dn;
int dn_slots = dnodesize >> DNODE_SHIFT;
int err;
if (dn_slots == 0)
dn_slots = DNODE_MIN_SLOTS;
ASSERT3S(dn_slots, >=, DNODE_MIN_SLOTS);
ASSERT3S(dn_slots, <=, DNODE_MAX_SLOTS);
if (object == DMU_META_DNODE_OBJECT && !dmu_tx_private_ok(tx))
return (SET_ERROR(EBADF));
err = dnode_hold_impl(os, object, DNODE_MUST_BE_FREE, dn_slots,
FTAG, &dn);
if (err)
return (err);
dnode_allocate(dn, ot, blocksize, 0, bonustype, bonuslen, dn_slots, tx);
dmu_tx_add_new_object(tx, dn);
dnode_rele(dn, FTAG);
return (0);
}
int
dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
return (dmu_object_reclaim_dnsize(os, object, ot, blocksize, bonustype,
bonuslen, DNODE_MIN_SIZE, B_FALSE, tx));
}
int
dmu_object_reclaim_dnsize(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonustype, int bonuslen, int dnodesize,
boolean_t keep_spill, dmu_tx_t *tx)
{
dnode_t *dn;
int dn_slots = dnodesize >> DNODE_SHIFT;
int err;
if (dn_slots == 0)
dn_slots = DNODE_MIN_SLOTS;
if (object == DMU_META_DNODE_OBJECT)
return (SET_ERROR(EBADF));
err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
FTAG, &dn);
if (err)
return (err);
dnode_reallocate(dn, ot, blocksize, bonustype, bonuslen, dn_slots,
keep_spill, tx);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_object_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
{
dnode_t *dn;
int err;
err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
FTAG, &dn);
if (err)
return (err);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
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);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx)
{
dnode_t *dn;
int err;
ASSERT(object != DMU_META_DNODE_OBJECT || dmu_tx_private_ok(tx));
err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
FTAG, &dn);
if (err)
return (err);
ASSERT(dn->dn_type != DMU_OT_NONE);
/*
* If we don't create this free range, we'll leak indirect blocks when
* we get to freeing the dnode in syncing context.
*/
dnode_free_range(dn, 0, DMU_OBJECT_END, tx);
dnode_free(dn, tx);
dnode_rele(dn, FTAG);
return (0);
}
/*
* Return (in *objectp) the next object which is allocated (or a hole)
* after *object, taking into account only objects that may have been modified
* after the specified txg.
*/
int
dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole, uint64_t txg)
{
uint64_t offset;
uint64_t start_obj;
struct dsl_dataset *ds = os->os_dsl_dataset;
int error;
if (*objectp == 0) {
start_obj = 1;
} else if (ds && dsl_dataset_feature_is_active(ds,
SPA_FEATURE_LARGE_DNODE)) {
uint64_t i = *objectp + 1;
uint64_t last_obj = *objectp | (DNODES_PER_BLOCK - 1);
dmu_object_info_t doi;
/*
* Scan through the remaining meta dnode block. The contents
* of each slot in the block are known so it can be quickly
* checked. If the block is exhausted without a match then
* hand off to dnode_next_offset() for further scanning.
*/
while (i <= last_obj) {
error = dmu_object_info(os, i, &doi);
if (error == ENOENT) {
if (hole) {
*objectp = i;
return (0);
} else {
i++;
}
} else if (error == EEXIST) {
i++;
} else if (error == 0) {
if (hole) {
i += doi.doi_dnodesize >> DNODE_SHIFT;
} else {
*objectp = i;
return (0);
}
} else {
return (error);
}
}
start_obj = i;
} else {
start_obj = *objectp + 1;
}
offset = start_obj << DNODE_SHIFT;
error = dnode_next_offset(DMU_META_DNODE(os),
(hole ? DNODE_FIND_HOLE : 0), &offset, 0, DNODES_PER_BLOCK, txg);
*objectp = offset >> DNODE_SHIFT;
return (error);
}
/*
* Turn this object from old_type into DMU_OTN_ZAP_METADATA, and bump the
* refcount on SPA_FEATURE_EXTENSIBLE_DATASET.
*
* Only for use from syncing context, on MOS objects.
*/
void
dmu_object_zapify(objset_t *mos, uint64_t object, dmu_object_type_t old_type,
dmu_tx_t *tx)
{
dnode_t *dn;
ASSERT(dmu_tx_is_syncing(tx));
VERIFY0(dnode_hold(mos, object, FTAG, &dn));
if (dn->dn_type == DMU_OTN_ZAP_METADATA) {
dnode_rele(dn, FTAG);
return;
}
ASSERT3U(dn->dn_type, ==, old_type);
ASSERT0(dn->dn_maxblkid);
/*
* We must initialize the ZAP data before changing the type,
* so that concurrent calls to *_is_zapified() can determine if
* the object has been completely zapified by checking the type.
*/
mzap_create_impl(dn, 0, 0, tx);
dn->dn_next_type[tx->tx_txg & TXG_MASK] = dn->dn_type =
DMU_OTN_ZAP_METADATA;
dnode_setdirty(dn, tx);
dnode_rele(dn, FTAG);
spa_feature_incr(dmu_objset_spa(mos),
SPA_FEATURE_EXTENSIBLE_DATASET, tx);
}
void
dmu_object_free_zapified(objset_t *mos, uint64_t object, dmu_tx_t *tx)
{
dnode_t *dn;
dmu_object_type_t t;
ASSERT(dmu_tx_is_syncing(tx));
VERIFY0(dnode_hold(mos, object, FTAG, &dn));
t = dn->dn_type;
dnode_rele(dn, FTAG);
if (t == DMU_OTN_ZAP_METADATA) {
spa_feature_decr(dmu_objset_spa(mos),
SPA_FEATURE_EXTENSIBLE_DATASET, tx);
}
VERIFY0(dmu_object_free(mos, object, tx));
}
EXPORT_SYMBOL(dmu_object_alloc);
EXPORT_SYMBOL(dmu_object_alloc_ibs);
EXPORT_SYMBOL(dmu_object_alloc_dnsize);
EXPORT_SYMBOL(dmu_object_alloc_hold);
EXPORT_SYMBOL(dmu_object_claim);
EXPORT_SYMBOL(dmu_object_claim_dnsize);
EXPORT_SYMBOL(dmu_object_reclaim);
EXPORT_SYMBOL(dmu_object_reclaim_dnsize);
EXPORT_SYMBOL(dmu_object_rm_spill);
EXPORT_SYMBOL(dmu_object_free);
EXPORT_SYMBOL(dmu_object_next);
EXPORT_SYMBOL(dmu_object_zapify);
EXPORT_SYMBOL(dmu_object_free_zapified);
/* BEGIN CSTYLED */
ZFS_MODULE_PARAM(zfs, , dmu_object_alloc_chunk_shift, UINT, ZMOD_RW,
"CPU-specific allocator grabs 2^N objects at once");
/* END CSTYLED */
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