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mirror_zfs/include/sys/dmu.h
Matthew Ahrens e8b96c6007 Illumos #4045 write throttle & i/o scheduler performance work 
4045 zfs write throttle & i/o scheduler performance work

1. The ZFS i/o scheduler (vdev_queue.c) now divides i/os into 5 classes: sync
read, sync write, async read, async write, and scrub/resilver.  The scheduler
issues a number of concurrent i/os from each class to the device.  Once a class
has been selected, an i/o is selected from this class using either an elevator
algorithem (async, scrub classes) or FIFO (sync classes).  The number of
concurrent async write i/os is tuned dynamically based on i/o load, to achieve
good sync i/o latency when there is not a high load of writes, and good write
throughput when there is.  See the block comment in vdev_queue.c (reproduced
below) for more details.

2. The write throttle (dsl_pool_tempreserve_space() and
txg_constrain_throughput()) is rewritten to produce much more consistent delays
when under constant load.  The new write throttle is based on the amount of
dirty data, rather than guesses about future performance of the system.  When
there is a lot of dirty data, each transaction (e.g. write() syscall) will be
delayed by the same small amount.  This eliminates the "brick wall of wait"
that the old write throttle could hit, causing all transactions to wait several
seconds until the next txg opens.  One of the keys to the new write throttle is
decrementing the amount of dirty data as i/o completes, rather than at the end
of spa_sync().  Note that the write throttle is only applied once the i/o
scheduler is issuing the maximum number of outstanding async writes.  See the
block comments in dsl_pool.c and above dmu_tx_delay() (reproduced below) for
more details.

This diff has several other effects, including:

 * the commonly-tuned global variable zfs_vdev_max_pending has been removed;
use per-class zfs_vdev_*_max_active values or zfs_vdev_max_active instead.

 * the size of each txg (meaning the amount of dirty data written, and thus the
time it takes to write out) is now controlled differently.  There is no longer
an explicit time goal; the primary determinant is amount of dirty data.
Systems that are under light or medium load will now often see that a txg is
always syncing, but the impact to performance (e.g. read latency) is minimal.
Tune zfs_dirty_data_max and zfs_dirty_data_sync to control this.

 * zio_taskq_batch_pct = 75 -- Only use 75% of all CPUs for compression,
checksum, etc.  This improves latency by not allowing these CPU-intensive tasks
to consume all CPU (on machines with at least 4 CPU's; the percentage is
rounded up).

--matt

APPENDIX: problems with the current i/o scheduler

The current ZFS i/o scheduler (vdev_queue.c) is deadline based.  The problem
with this is that if there are always i/os pending, then certain classes of
i/os can see very long delays.

For example, if there are always synchronous reads outstanding, then no async
writes will be serviced until they become "past due".  One symptom of this
situation is that each pass of the txg sync takes at least several seconds
(typically 3 seconds).

If many i/os become "past due" (their deadline is in the past), then we must
service all of these overdue i/os before any new i/os.  This happens when we
enqueue a batch of async writes for the txg sync, with deadlines 2.5 seconds in
the future.  If we can't complete all the i/os in 2.5 seconds (e.g. because
there were always reads pending), then these i/os will become past due.  Now we
must service all the "async" writes (which could be hundreds of megabytes)
before we service any reads, introducing considerable latency to synchronous
i/os (reads or ZIL writes).

Notes on porting to ZFS on Linux:

- zio_t gained new members io_physdone and io_phys_children.  Because
  object caches in the Linux port call the constructor only once at
  allocation time, objects may contain residual data when retrieved
  from the cache. Therefore zio_create() was updated to zero out the two
  new fields.

- vdev_mirror_pending() relied on the depth of the per-vdev pending queue
  (vq->vq_pending_tree) to select the least-busy leaf vdev to read from.
  This tree has been replaced by vq->vq_active_tree which is now used
  for the same purpose.

- vdev_queue_init() used the value of zfs_vdev_max_pending to determine
  the number of vdev I/O buffers to pre-allocate.  That global no longer
  exists, so we instead use the sum of the *_max_active values for each of
  the five I/O classes described above.

- The Illumos implementation of dmu_tx_delay() delays a transaction by
  sleeping in condition variable embedded in the thread
  (curthread->t_delay_cv).  We do not have an equivalent CV to use in
  Linux, so this change replaced the delay logic with a wrapper called
  zfs_sleep_until(). This wrapper could be adopted upstream and in other
  downstream ports to abstract away operating system-specific delay logic.

- These tunables are added as module parameters, and descriptions added
  to the zfs-module-parameters.5 man page.

  spa_asize_inflation
  zfs_deadman_synctime_ms
  zfs_vdev_max_active
  zfs_vdev_async_write_active_min_dirty_percent
  zfs_vdev_async_write_active_max_dirty_percent
  zfs_vdev_async_read_max_active
  zfs_vdev_async_read_min_active
  zfs_vdev_async_write_max_active
  zfs_vdev_async_write_min_active
  zfs_vdev_scrub_max_active
  zfs_vdev_scrub_min_active
  zfs_vdev_sync_read_max_active
  zfs_vdev_sync_read_min_active
  zfs_vdev_sync_write_max_active
  zfs_vdev_sync_write_min_active
  zfs_dirty_data_max_percent
  zfs_delay_min_dirty_percent
  zfs_dirty_data_max_max_percent
  zfs_dirty_data_max
  zfs_dirty_data_max_max
  zfs_dirty_data_sync
  zfs_delay_scale

  The latter four have type unsigned long, whereas they are uint64_t in
  Illumos.  This accommodates Linux's module_param() supported types, but
  means they may overflow on 32-bit architectures.

  The values zfs_dirty_data_max and zfs_dirty_data_max_max are the most
  likely to overflow on 32-bit systems, since they express physical RAM
  sizes in bytes.  In fact, Illumos initializes zfs_dirty_data_max_max to
  2^32 which does overflow. To resolve that, this port instead initializes
  it in arc_init() to 25% of physical RAM, and adds the tunable
  zfs_dirty_data_max_max_percent to override that percentage.  While this
  solution doesn't completely avoid the overflow issue, it should be a
  reasonable default for most systems, and the minority of affected
  systems can work around the issue by overriding the defaults.

- Fixed reversed logic in comment above zfs_delay_scale declaration.

- Clarified comments in vdev_queue.c regarding when per-queue minimums take
  effect.

- Replaced dmu_tx_write_limit in the dmu_tx kstat file
  with dmu_tx_dirty_delay and dmu_tx_dirty_over_max.  The first counts
  how many times a transaction has been delayed because the pool dirty
  data has exceeded zfs_delay_min_dirty_percent.  The latter counts how
  many times the pool dirty data has exceeded zfs_dirty_data_max (which
  we expect to never happen).

- The original patch would have regressed the bug fixed in
  zfsonlinux/zfs@c418410, which prevented users from setting the
  zfs_vdev_aggregation_limit tuning larger than SPA_MAXBLOCKSIZE.
  A similar fix is added to vdev_queue_aggregate().

- In vdev_queue_io_to_issue(), dynamically allocate 'zio_t search' on the
  heap instead of the stack.  In Linux we can't afford such large
  structures on the stack.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Ned Bass <bass6@llnl.gov>
Reviewed by: Brendan Gregg <brendan.gregg@joyent.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  http://www.illumos.org/issues/4045
  illumos/illumos-gate@69962b5647

Ported-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1913
2013-12-06 09:32:43 -08:00

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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 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.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2012, Joyent, Inc. All rights reserved.
*/
/* Portions Copyright 2010 Robert Milkowski */
#ifndef _SYS_DMU_H
#define _SYS_DMU_H
/*
* This file describes the interface that the DMU provides for its
* consumers.
*
* The DMU also interacts with the SPA. That interface is described in
* dmu_spa.h.
*/
#include <sys/inttypes.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/cred.h>
#include <sys/time.h>
#include <sys/fs/zfs.h>
#include <sys/uio.h>
#ifdef __cplusplus
extern "C" {
#endif
struct page;
struct vnode;
struct spa;
struct zilog;
struct zio;
struct blkptr;
struct zap_cursor;
struct dsl_dataset;
struct dsl_pool;
struct dnode;
struct drr_begin;
struct drr_end;
struct zbookmark;
struct spa;
struct nvlist;
struct arc_buf;
struct zio_prop;
struct sa_handle;
typedef struct objset objset_t;
typedef struct dmu_tx dmu_tx_t;
typedef struct dsl_dir dsl_dir_t;
typedef enum dmu_object_byteswap {
DMU_BSWAP_UINT8,
DMU_BSWAP_UINT16,
DMU_BSWAP_UINT32,
DMU_BSWAP_UINT64,
DMU_BSWAP_ZAP,
DMU_BSWAP_DNODE,
DMU_BSWAP_OBJSET,
DMU_BSWAP_ZNODE,
DMU_BSWAP_OLDACL,
DMU_BSWAP_ACL,
/*
* Allocating a new byteswap type number makes the on-disk format
* incompatible with any other format that uses the same number.
*
* Data can usually be structured to work with one of the
* DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
*/
DMU_BSWAP_NUMFUNCS
} dmu_object_byteswap_t;
#define DMU_OT_NEWTYPE 0x80
#define DMU_OT_METADATA 0x40
#define DMU_OT_BYTESWAP_MASK 0x3f
/*
* Defines a uint8_t object type. Object types specify if the data
* in the object is metadata (boolean) and how to byteswap the data
* (dmu_object_byteswap_t).
*/
#define DMU_OT(byteswap, metadata) \
(DMU_OT_NEWTYPE | \
((metadata) ? DMU_OT_METADATA : 0) | \
((byteswap) & DMU_OT_BYTESWAP_MASK))
#define DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
(ot) < DMU_OT_NUMTYPES)
#define DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
((ot) & DMU_OT_METADATA) : \
dmu_ot[(int)(ot)].ot_metadata)
#define DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
((ot) & DMU_OT_BYTESWAP_MASK) : \
dmu_ot[(int)(ot)].ot_byteswap)
typedef enum dmu_object_type {
DMU_OT_NONE,
/* general: */
DMU_OT_OBJECT_DIRECTORY, /* ZAP */
DMU_OT_OBJECT_ARRAY, /* UINT64 */
DMU_OT_PACKED_NVLIST, /* UINT8 (XDR by nvlist_pack/unpack) */
DMU_OT_PACKED_NVLIST_SIZE, /* UINT64 */
DMU_OT_BPOBJ, /* UINT64 */
DMU_OT_BPOBJ_HDR, /* UINT64 */
/* spa: */
DMU_OT_SPACE_MAP_HEADER, /* UINT64 */
DMU_OT_SPACE_MAP, /* UINT64 */
/* zil: */
DMU_OT_INTENT_LOG, /* UINT64 */
/* dmu: */
DMU_OT_DNODE, /* DNODE */
DMU_OT_OBJSET, /* OBJSET */
/* dsl: */
DMU_OT_DSL_DIR, /* UINT64 */
DMU_OT_DSL_DIR_CHILD_MAP, /* ZAP */
DMU_OT_DSL_DS_SNAP_MAP, /* ZAP */
DMU_OT_DSL_PROPS, /* ZAP */
DMU_OT_DSL_DATASET, /* UINT64 */
/* zpl: */
DMU_OT_ZNODE, /* ZNODE */
DMU_OT_OLDACL, /* Old ACL */
DMU_OT_PLAIN_FILE_CONTENTS, /* UINT8 */
DMU_OT_DIRECTORY_CONTENTS, /* ZAP */
DMU_OT_MASTER_NODE, /* ZAP */
DMU_OT_UNLINKED_SET, /* ZAP */
/* zvol: */
DMU_OT_ZVOL, /* UINT8 */
DMU_OT_ZVOL_PROP, /* ZAP */
/* other; for testing only! */
DMU_OT_PLAIN_OTHER, /* UINT8 */
DMU_OT_UINT64_OTHER, /* UINT64 */
DMU_OT_ZAP_OTHER, /* ZAP */
/* new object types: */
DMU_OT_ERROR_LOG, /* ZAP */
DMU_OT_SPA_HISTORY, /* UINT8 */
DMU_OT_SPA_HISTORY_OFFSETS, /* spa_his_phys_t */
DMU_OT_POOL_PROPS, /* ZAP */
DMU_OT_DSL_PERMS, /* ZAP */
DMU_OT_ACL, /* ACL */
DMU_OT_SYSACL, /* SYSACL */
DMU_OT_FUID, /* FUID table (Packed NVLIST UINT8) */
DMU_OT_FUID_SIZE, /* FUID table size UINT64 */
DMU_OT_NEXT_CLONES, /* ZAP */
DMU_OT_SCAN_QUEUE, /* ZAP */
DMU_OT_USERGROUP_USED, /* ZAP */
DMU_OT_USERGROUP_QUOTA, /* ZAP */
DMU_OT_USERREFS, /* ZAP */
DMU_OT_DDT_ZAP, /* ZAP */
DMU_OT_DDT_STATS, /* ZAP */
DMU_OT_SA, /* System attr */
DMU_OT_SA_MASTER_NODE, /* ZAP */
DMU_OT_SA_ATTR_REGISTRATION, /* ZAP */
DMU_OT_SA_ATTR_LAYOUTS, /* ZAP */
DMU_OT_SCAN_XLATE, /* ZAP */
DMU_OT_DEDUP, /* fake dedup BP from ddt_bp_create() */
DMU_OT_DEADLIST, /* ZAP */
DMU_OT_DEADLIST_HDR, /* UINT64 */
DMU_OT_DSL_CLONES, /* ZAP */
DMU_OT_BPOBJ_SUBOBJ, /* UINT64 */
/*
* Do not allocate new object types here. Doing so makes the on-disk
* format incompatible with any other format that uses the same object
* type number.
*
* When creating an object which does not have one of the above types
* use the DMU_OTN_* type with the correct byteswap and metadata
* values.
*
* The DMU_OTN_* types do not have entries in the dmu_ot table,
* use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
* of indexing into dmu_ot directly (this works for both DMU_OT_* types
* and DMU_OTN_* types).
*/
DMU_OT_NUMTYPES,
/*
* Names for valid types declared with DMU_OT().
*/
DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
} dmu_object_type_t;
typedef enum txg_how {
TXG_WAIT = 1,
TXG_NOWAIT,
TXG_WAITED,
} txg_how_t;
void byteswap_uint64_array(void *buf, size_t size);
void byteswap_uint32_array(void *buf, size_t size);
void byteswap_uint16_array(void *buf, size_t size);
void byteswap_uint8_array(void *buf, size_t size);
void zap_byteswap(void *buf, size_t size);
void zfs_oldacl_byteswap(void *buf, size_t size);
void zfs_acl_byteswap(void *buf, size_t size);
void zfs_znode_byteswap(void *buf, size_t size);
#define DS_FIND_SNAPSHOTS (1<<0)
#define DS_FIND_CHILDREN (1<<1)
/*
* The maximum number of bytes that can be accessed as part of one
* operation, including metadata.
*/
#define DMU_MAX_ACCESS (10<<20) /* 10MB */
#define DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
#define DMU_USERUSED_OBJECT (-1ULL)
#define DMU_GROUPUSED_OBJECT (-2ULL)
#define DMU_DEADLIST_OBJECT (-3ULL)
/*
* artificial blkids for bonus buffer and spill blocks
*/
#define DMU_BONUS_BLKID (-1ULL)
#define DMU_SPILL_BLKID (-2ULL)
/*
* Public routines to create, destroy, open, and close objsets.
*/
int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
int dmu_objset_own(const char *name, dmu_objset_type_t type,
boolean_t readonly, void *tag, objset_t **osp);
void dmu_objset_rele(objset_t *os, void *tag);
void dmu_objset_disown(objset_t *os, void *tag);
int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
void dmu_objset_evict_dbufs(objset_t *os);
int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
int dmu_objset_clone(const char *name, const char *origin);
int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
struct nvlist *errlist);
int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
int dmu_objset_snapshot_tmp(const char *, const char *, int);
int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
int flags);
void dmu_objset_byteswap(void *buf, size_t size);
int dsl_dataset_rename_snapshot(const char *fsname,
const char *oldsnapname, const char *newsnapname, boolean_t recursive);
typedef struct dmu_buf {
uint64_t db_object; /* object that this buffer is part of */
uint64_t db_offset; /* byte offset in this object */
uint64_t db_size; /* size of buffer in bytes */
void *db_data; /* data in buffer */
} dmu_buf_t;
typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
/*
* The names of zap entries in the DIRECTORY_OBJECT of the MOS.
*/
#define DMU_POOL_DIRECTORY_OBJECT 1
#define DMU_POOL_CONFIG "config"
#define DMU_POOL_FEATURES_FOR_WRITE "features_for_write"
#define DMU_POOL_FEATURES_FOR_READ "features_for_read"
#define DMU_POOL_FEATURE_DESCRIPTIONS "feature_descriptions"
#define DMU_POOL_ROOT_DATASET "root_dataset"
#define DMU_POOL_SYNC_BPOBJ "sync_bplist"
#define DMU_POOL_ERRLOG_SCRUB "errlog_scrub"
#define DMU_POOL_ERRLOG_LAST "errlog_last"
#define DMU_POOL_SPARES "spares"
#define DMU_POOL_DEFLATE "deflate"
#define DMU_POOL_HISTORY "history"
#define DMU_POOL_PROPS "pool_props"
#define DMU_POOL_L2CACHE "l2cache"
#define DMU_POOL_TMP_USERREFS "tmp_userrefs"
#define DMU_POOL_DDT "DDT-%s-%s-%s"
#define DMU_POOL_DDT_STATS "DDT-statistics"
#define DMU_POOL_CREATION_VERSION "creation_version"
#define DMU_POOL_SCAN "scan"
#define DMU_POOL_FREE_BPOBJ "free_bpobj"
#define DMU_POOL_BPTREE_OBJ "bptree_obj"
#define DMU_POOL_EMPTY_BPOBJ "empty_bpobj"
/*
* Allocate an object from this objset. The range of object numbers
* available is (0, DN_MAX_OBJECT). Object 0 is the meta-dnode.
*
* The transaction must be assigned to a txg. The newly allocated
* object will be "held" in the transaction (ie. you can modify the
* newly allocated object in this transaction).
*
* dmu_object_alloc() chooses an object and returns it in *objectp.
*
* dmu_object_claim() allocates a specific object number. If that
* number is already allocated, it fails and returns EEXIST.
*
* Return 0 on success, or ENOSPC or EEXIST as specified above.
*/
uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
int blocksize, dmu_object_type_t bonustype, int bonuslen);
/*
* Free an object from this objset.
*
* The object's data will be freed as well (ie. you don't need to call
* dmu_free(object, 0, -1, tx)).
*
* The object need not be held in the transaction.
*
* If there are any holds on this object's buffers (via dmu_buf_hold()),
* or tx holds on the object (via dmu_tx_hold_object()), you can not
* free it; it fails and returns EBUSY.
*
* If the object is not allocated, it fails and returns ENOENT.
*
* Return 0 on success, or EBUSY or ENOENT as specified above.
*/
int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
/*
* Find the next allocated or free object.
*
* The objectp parameter is in-out. It will be updated to be the next
* object which is allocated. Ignore objects which have not been
* modified since txg.
*
* XXX Can only be called on a objset with no dirty data.
*
* Returns 0 on success, or ENOENT if there are no more objects.
*/
int dmu_object_next(objset_t *os, uint64_t *objectp,
boolean_t hole, uint64_t txg);
/*
* Set the data blocksize for an object.
*
* The object cannot have any blocks allcated beyond the first. If
* the first block is allocated already, the new size must be greater
* than the current block size. If these conditions are not met,
* ENOTSUP will be returned.
*
* Returns 0 on success, or EBUSY if there are any holds on the object
* contents, or ENOTSUP as described above.
*/
int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
int ibs, dmu_tx_t *tx);
/*
* Set the checksum property on a dnode. The new checksum algorithm will
* apply to all newly written blocks; existing blocks will not be affected.
*/
void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
dmu_tx_t *tx);
/*
* Set the compress property on a dnode. The new compression algorithm will
* apply to all newly written blocks; existing blocks will not be affected.
*/
void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
dmu_tx_t *tx);
/*
* Decide how to write a block: checksum, compression, number of copies, etc.
*/
#define WP_NOFILL 0x1
#define WP_DMU_SYNC 0x2
#define WP_SPILL 0x4
void dmu_write_policy(objset_t *os, struct dnode *dn, int level, int wp,
struct zio_prop *zp);
/*
* The bonus data is accessed more or less like a regular buffer.
* You must dmu_bonus_hold() to get the buffer, which will give you a
* dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
* data. As with any normal buffer, you must call dmu_buf_read() to
* read db_data, dmu_buf_will_dirty() before modifying it, and the
* object must be held in an assigned transaction before calling
* dmu_buf_will_dirty. You may use dmu_buf_set_user() on the bonus
* buffer as well. You must release what you hold with dmu_buf_rele().
*
* Returns ENOENT, EIO, or 0.
*/
int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
int dmu_bonus_max(void);
int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
/*
* Special spill buffer support used by "SA" framework
*/
int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
int dmu_spill_hold_by_dnode(struct dnode *dn, uint32_t flags,
void *tag, dmu_buf_t **dbp);
int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
/*
* Obtain the DMU buffer from the specified object which contains the
* specified offset. dmu_buf_hold() puts a "hold" on the buffer, so
* that it will remain in memory. You must release the hold with
* dmu_buf_rele(). You must not access the dmu_buf_t after releasing
* what you hold. You must have a hold on any dmu_buf_t* you pass to the DMU.
*
* You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
* on the returned buffer before reading or writing the buffer's
* db_data. The comments for those routines describe what particular
* operations are valid after calling them.
*
* The object number must be a valid, allocated object number.
*/
int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
void *tag, dmu_buf_t **, int flags);
void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
void dmu_buf_rele(dmu_buf_t *db, void *tag);
uint64_t dmu_buf_refcount(dmu_buf_t *db);
/*
* dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
* range of an object. A pointer to an array of dmu_buf_t*'s is
* returned (in *dbpp).
*
* dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
* frees the array. The hold on the array of buffers MUST be released
* with dmu_buf_rele_array. You can NOT release the hold on each buffer
* individually with dmu_buf_rele.
*/
int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
/*
* Returns NULL on success, or the existing user ptr if it's already
* been set.
*
* user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
*
* user_data_ptr_ptr should be NULL, or a pointer to a pointer which
* will be set to db->db_data when you are allowed to access it. Note
* that db->db_data (the pointer) can change when you do dmu_buf_read(),
* dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
* *user_data_ptr_ptr will be set to the new value when it changes.
*
* If non-NULL, pageout func will be called when this buffer is being
* excised from the cache, so that you can clean up the data structure
* pointed to by user_ptr.
*
* dmu_evict_user() will call the pageout func for all buffers in a
* objset with a given pageout func.
*/
void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
dmu_buf_evict_func_t *pageout_func);
/*
* set_user_ie is the same as set_user, but request immediate eviction
* when hold count goes to zero.
*/
void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
void *user_ptr, void *user_data_ptr_ptr,
dmu_buf_evict_func_t *pageout_func);
void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
/*
* Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
*/
void *dmu_buf_get_user(dmu_buf_t *db);
/*
* Returns the blkptr associated with this dbuf, or NULL if not set.
*/
struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
/*
* Indicate that you are going to modify the buffer's data (db_data).
*
* The transaction (tx) must be assigned to a txg (ie. you've called
* dmu_tx_assign()). The buffer's object must be held in the tx
* (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
*/
void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
/*
* Tells if the given dbuf is freeable.
*/
boolean_t dmu_buf_freeable(dmu_buf_t *);
/*
* You must create a transaction, then hold the objects which you will
* (or might) modify as part of this transaction. Then you must assign
* the transaction to a transaction group. Once the transaction has
* been assigned, you can modify buffers which belong to held objects as
* part of this transaction. You can't modify buffers before the
* transaction has been assigned; you can't modify buffers which don't
* belong to objects which this transaction holds; you can't hold
* objects once the transaction has been assigned. You may hold an
* object which you are going to free (with dmu_object_free()), but you
* don't have to.
*
* You can abort the transaction before it has been assigned.
*
* Note that you may hold buffers (with dmu_buf_hold) at any time,
* regardless of transaction state.
*/
#define DMU_NEW_OBJECT (-1ULL)
#define DMU_OBJECT_END (-1ULL)
dmu_tx_t *dmu_tx_create(objset_t *os);
void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
uint64_t len);
void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
void dmu_tx_abort(dmu_tx_t *tx);
int dmu_tx_assign(dmu_tx_t *tx, enum txg_how txg_how);
void dmu_tx_wait(dmu_tx_t *tx);
void dmu_tx_commit(dmu_tx_t *tx);
/*
* To register a commit callback, dmu_tx_callback_register() must be called.
*
* dcb_data is a pointer to caller private data that is passed on as a
* callback parameter. The caller is responsible for properly allocating and
* freeing it.
*
* When registering a callback, the transaction must be already created, but
* it cannot be committed or aborted. It can be assigned to a txg or not.
*
* The callback will be called after the transaction has been safely written
* to stable storage and will also be called if the dmu_tx is aborted.
* If there is any error which prevents the transaction from being committed to
* disk, the callback will be called with a value of error != 0.
*/
typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
void *dcb_data);
/*
* Free up the data blocks for a defined range of a file. If size is
* -1, the range from offset to end-of-file is freed.
*/
int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
uint64_t size, dmu_tx_t *tx);
int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
uint64_t size);
int dmu_free_long_object(objset_t *os, uint64_t object);
/*
* Convenience functions.
*
* Canfail routines will return 0 on success, or an errno if there is a
* nonrecoverable I/O error.
*/
#define DMU_READ_PREFETCH 0 /* prefetch */
#define DMU_READ_NO_PREFETCH 1 /* don't prefetch */
int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
void *buf, uint32_t flags);
void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
const void *buf, dmu_tx_t *tx);
void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
dmu_tx_t *tx);
#ifdef _KERNEL
#include <linux/blkdev_compat.h>
int dmu_read_req(objset_t *os, uint64_t object, struct request *req);
int dmu_write_req(objset_t *os, uint64_t object, struct request *req,
dmu_tx_t *tx);
int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
dmu_tx_t *tx);
int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
dmu_tx_t *tx);
#endif
struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
void dmu_return_arcbuf(struct arc_buf *buf);
void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
dmu_tx_t *tx);
int dmu_xuio_init(struct xuio *uio, int niov);
void dmu_xuio_fini(struct xuio *uio);
int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
size_t n);
int dmu_xuio_cnt(struct xuio *uio);
struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
void dmu_xuio_clear(struct xuio *uio, int i);
void xuio_stat_wbuf_copied(void);
void xuio_stat_wbuf_nocopy(void);
extern int zfs_prefetch_disable;
/*
* Asynchronously try to read in the data.
*/
void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
uint64_t len);
typedef struct dmu_object_info {
/* All sizes are in bytes unless otherwise indicated. */
uint32_t doi_data_block_size;
uint32_t doi_metadata_block_size;
dmu_object_type_t doi_type;
dmu_object_type_t doi_bonus_type;
uint64_t doi_bonus_size;
uint8_t doi_indirection; /* 2 = dnode->indirect->data */
uint8_t doi_checksum;
uint8_t doi_compress;
uint8_t doi_pad[5];
uint64_t doi_physical_blocks_512; /* data + metadata, 512b blks */
uint64_t doi_max_offset;
uint64_t doi_fill_count; /* number of non-empty blocks */
} dmu_object_info_t;
typedef void (*const arc_byteswap_func_t)(void *buf, size_t size);
typedef struct dmu_object_type_info {
dmu_object_byteswap_t ot_byteswap;
boolean_t ot_metadata;
char *ot_name;
} dmu_object_type_info_t;
typedef const struct dmu_object_byteswap_info {
arc_byteswap_func_t ob_func;
char *ob_name;
} dmu_object_byteswap_info_t;
extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
/*
* Get information on a DMU object.
*
* Return 0 on success or ENOENT if object is not allocated.
*
* If doi is NULL, just indicates whether the object exists.
*/
int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
void __dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
/* Like dmu_object_info, but faster if you have a held dnode in hand. */
void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
/* Like dmu_object_info, but faster if you have a held dbuf in hand. */
void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
/*
* Like dmu_object_info_from_db, but faster still when you only care about
* the size. This is specifically optimized for zfs_getattr().
*/
void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
u_longlong_t *nblk512);
typedef struct dmu_objset_stats {
uint64_t dds_num_clones; /* number of clones of this */
uint64_t dds_creation_txg;
uint64_t dds_guid;
dmu_objset_type_t dds_type;
uint8_t dds_is_snapshot;
uint8_t dds_inconsistent;
char dds_origin[MAXNAMELEN];
} dmu_objset_stats_t;
/*
* Get stats on a dataset.
*/
void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
/*
* Add entries to the nvlist for all the objset's properties. See
* zfs_prop_table[] and zfs(1m) for details on the properties.
*/
void dmu_objset_stats(objset_t *os, struct nvlist *nv);
/*
* Get the space usage statistics for statvfs().
*
* refdbytes is the amount of space "referenced" by this objset.
* availbytes is the amount of space available to this objset, taking
* into account quotas & reservations, assuming that no other objsets
* use the space first. These values correspond to the 'referenced' and
* 'available' properties, described in the zfs(1m) manpage.
*
* usedobjs and availobjs are the number of objects currently allocated,
* and available.
*/
void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
uint64_t *usedobjsp, uint64_t *availobjsp);
/*
* The fsid_guid is a 56-bit ID that can change to avoid collisions.
* (Contrast with the ds_guid which is a 64-bit ID that will never
* change, so there is a small probability that it will collide.)
*/
uint64_t dmu_objset_fsid_guid(objset_t *os);
/*
* Get the [cm]time for an objset's snapshot dir
*/
timestruc_t dmu_objset_snap_cmtime(objset_t *os);
int dmu_objset_is_snapshot(objset_t *os);
extern struct spa *dmu_objset_spa(objset_t *os);
extern struct zilog *dmu_objset_zil(objset_t *os);
extern struct dsl_pool *dmu_objset_pool(objset_t *os);
extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
extern void dmu_objset_name(objset_t *os, char *buf);
extern dmu_objset_type_t dmu_objset_type(objset_t *os);
extern uint64_t dmu_objset_id(objset_t *os);
extern uint64_t dmu_objset_syncprop(objset_t *os);
extern uint64_t dmu_objset_logbias(objset_t *os);
extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
extern int dmu_snapshot_lookup(objset_t *os, const char *name, uint64_t *val);
extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
int maxlen, boolean_t *conflict);
extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
uint64_t *idp, uint64_t *offp);
typedef int objset_used_cb_t(dmu_object_type_t bonustype,
void *bonus, uint64_t *userp, uint64_t *groupp);
extern void dmu_objset_register_type(dmu_objset_type_t ost,
objset_used_cb_t *cb);
extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
extern void *dmu_objset_get_user(objset_t *os);
/*
* Return the txg number for the given assigned transaction.
*/
uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
/*
* Synchronous write.
* If a parent zio is provided this function initiates a write on the
* provided buffer as a child of the parent zio.
* In the absence of a parent zio, the write is completed synchronously.
* At write completion, blk is filled with the bp of the written block.
* Note that while the data covered by this function will be on stable
* storage when the write completes this new data does not become a
* permanent part of the file until the associated transaction commits.
*/
/*
* {zfs,zvol,ztest}_get_done() args
*/
typedef struct zgd {
struct zilog *zgd_zilog;
struct blkptr *zgd_bp;
dmu_buf_t *zgd_db;
struct rl *zgd_rl;
void *zgd_private;
} zgd_t;
typedef void dmu_sync_cb_t(zgd_t *arg, int error);
int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
/*
* Find the next hole or data block in file starting at *off
* Return found offset in *off. Return ESRCH for end of file.
*/
int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
uint64_t *off);
/*
* Initial setup and final teardown.
*/
extern void dmu_init(void);
extern void dmu_fini(void);
typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
uint64_t object, uint64_t offset, int len);
void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
dmu_traverse_cb_t cb, void *arg);
int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
struct vnode *vp, offset_t *offp);
/* CRC64 table */
#define ZFS_CRC64_POLY 0xC96C5795D7870F42ULL /* ECMA-182, reflected form */
extern uint64_t zfs_crc64_table[256];
extern int zfs_mdcomp_disable;
#ifdef __cplusplus
}
#endif
#endif /* _SYS_DMU_H */
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