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mirror_zfs/include/sys/dmu_objset.h
Brian Atkinson a10e552b99
Adding Direct IO Support 
Adding O_DIRECT support to ZFS to bypass the ARC for writes/reads.

O_DIRECT support in ZFS will always ensure there is coherency between
buffered and O_DIRECT IO requests. This ensures that all IO requests,
whether buffered or direct, will see the same file contents at all
times. Just as in other FS's , O_DIRECT does not imply O_SYNC. While
data is written directly to VDEV disks, metadata will not be synced
until the associated  TXG is synced.
For both O_DIRECT read and write request the offset and request sizes,
at a minimum, must be PAGE_SIZE aligned. In the event they are not,
then EINVAL is returned unless the direct property is set to always (see
below).

For O_DIRECT writes:
The request also must be block aligned (recordsize) or the write
request will take the normal (buffered) write path. In the event that
request is block aligned and a cached copy of the buffer in the ARC,
then it will be discarded from the ARC forcing all further reads to
retrieve the data from disk.

For O_DIRECT reads:
The only alignment restrictions are PAGE_SIZE alignment. In the event
that the requested data is in buffered (in the ARC) it will just be
copied from the ARC into the user buffer.

For both O_DIRECT writes and reads the O_DIRECT flag will be ignored in
the event that file contents are mmap'ed. In this case, all requests
that are at least PAGE_SIZE aligned will just fall back to the buffered
paths. If the request however is not PAGE_SIZE aligned, EINVAL will
be returned as always regardless if the file's contents are mmap'ed.

Since O_DIRECT writes go through the normal ZIO pipeline, the
following operations are supported just as with normal buffered writes:
Checksum
Compression
Encryption
Erasure Coding
There is one caveat for the data integrity of O_DIRECT writes that is
distinct for each of the OS's supported by ZFS.
FreeBSD - FreeBSD is able to place user pages under write protection so
          any data in the user buffers and written directly down to the
	  VDEV disks is guaranteed to not change. There is no concern
	  with data integrity and O_DIRECT writes.
Linux - Linux is not able to place anonymous user pages under write
        protection. Because of this, if the user decides to manipulate
	the page contents while the write operation is occurring, data
	integrity can not be guaranteed. However, there is a module
	parameter `zfs_vdev_direct_write_verify` that controls the
	if a O_DIRECT writes that can occur to a top-level VDEV before
	a checksum verify is run before the contents of the I/O buffer
        are committed to disk. In the event of a checksum verification
	failure the write will return EIO. The number of O_DIRECT write
	checksum verification errors can be observed by doing
	`zpool status -d`, which will list all verification errors that
	have occurred on a top-level VDEV. Along with `zpool status`, a
	ZED event will be issues as `dio_verify` when a checksum
	verification error occurs.

ZVOLs and dedup is not currently supported with Direct I/O.

A new dataset property `direct` has been added with the following 3
allowable values:
disabled - Accepts O_DIRECT flag, but silently ignores it and treats
	   the request as a buffered IO request.
standard - Follows the alignment restrictions  outlined above for
	   write/read IO requests when the O_DIRECT flag is used.
always   - Treats every write/read IO request as though it passed
           O_DIRECT and will do O_DIRECT if the alignment restrictions
	   are met otherwise will redirect through the ARC. This
	   property will not allow a request to fail.

There is also a module parameter zfs_dio_enabled that can be used to
force all reads and writes through the ARC. By setting this module
parameter to 0, it mimics as if the  direct dataset property is set to
disabled.

Reviewed-by: Brian Behlendorf <behlendorf@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Co-authored-by: Mark Maybee <mark.maybee@delphix.com>
Co-authored-by: Matt Macy <mmacy@FreeBSD.org>
Co-authored-by: Brian Behlendorf <behlendorf@llnl.gov>
Closes #10018
2024-09-14 13:47:59 -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.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/
/* Portions Copyright 2010 Robert Milkowski */
#ifndef _SYS_DMU_OBJSET_H
#define _SYS_DMU_OBJSET_H
#include <sys/spa.h>
#include <sys/arc.h>
#include <sys/txg.h>
#include <sys/zfs_context.h>
#include <sys/dnode.h>
#include <sys/zio.h>
#include <sys/zil.h>
#include <sys/sa.h>
#include <sys/zfs_ioctl.h>
#ifdef __cplusplus
extern "C" {
#endif
extern krwlock_t os_lock;
struct dsl_pool;
struct dsl_dataset;
struct dmu_tx;
#define OBJSET_PHYS_SIZE_V1 1024
#define OBJSET_PHYS_SIZE_V2 2048
#define OBJSET_PHYS_SIZE_V3 4096
#define OBJSET_BUF_HAS_USERUSED(buf) \
(arc_buf_size(buf) >= OBJSET_PHYS_SIZE_V2)
#define OBJSET_BUF_HAS_PROJECTUSED(buf) \
(arc_buf_size(buf) >= OBJSET_PHYS_SIZE_V3)
#define OBJSET_FLAG_USERACCOUNTING_COMPLETE (1ULL << 0)
#define OBJSET_FLAG_USEROBJACCOUNTING_COMPLETE (1ULL << 1)
#define OBJSET_FLAG_PROJECTQUOTA_COMPLETE (1ULL << 2)
/*
* This mask defines the set of flags which are "portable", meaning
* that they can be preserved when doing a raw encrypted zfs send.
* Flags included in this mask will be protected by os_portable_mac
* when the block of dnodes is encrypted. No portable flags currently
* exist.
*/
#define OBJSET_CRYPT_PORTABLE_FLAGS_MASK (0)
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu-variable-sized-type-not-at-end"
#endif
typedef struct objset_phys {
dnode_phys_t os_meta_dnode;
zil_header_t os_zil_header;
uint64_t os_type;
uint64_t os_flags;
uint8_t os_portable_mac[ZIO_OBJSET_MAC_LEN];
uint8_t os_local_mac[ZIO_OBJSET_MAC_LEN];
char os_pad0[OBJSET_PHYS_SIZE_V2 - sizeof (dnode_phys_t)*3 -
sizeof (zil_header_t) - sizeof (uint64_t)*2 -
2*ZIO_OBJSET_MAC_LEN];
dnode_phys_t os_userused_dnode;
dnode_phys_t os_groupused_dnode;
dnode_phys_t os_projectused_dnode;
char os_pad1[OBJSET_PHYS_SIZE_V3 - OBJSET_PHYS_SIZE_V2 -
sizeof (dnode_phys_t)];
} objset_phys_t;
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
typedef int (*dmu_objset_upgrade_cb_t)(objset_t *);
#define OBJSET_PROP_UNINITIALIZED ((uint64_t)-1)
struct objset {
/* Immutable: */
struct dsl_dataset *os_dsl_dataset;
spa_t *os_spa;
arc_buf_t *os_phys_buf;
objset_phys_t *os_phys;
boolean_t os_encrypted;
/*
* The following "special" dnodes have no parent, are exempt
* from dnode_move(), and are not recorded in os_dnodes, but they
* root their descendents in this objset using handles anyway, so
* that all access to dnodes from dbufs consistently uses handles.
*/
dnode_handle_t os_meta_dnode;
dnode_handle_t os_userused_dnode;
dnode_handle_t os_groupused_dnode;
dnode_handle_t os_projectused_dnode;
zilog_t *os_zil;
list_node_t os_evicting_node;
/* can change, under dsl_dir's locks: */
uint64_t os_dnodesize; /* default dnode size for new objects */
enum zio_checksum os_checksum;
enum zio_compress os_compress;
uint8_t os_complevel;
uint8_t os_copies;
enum zio_checksum os_dedup_checksum;
boolean_t os_dedup_verify;
zfs_logbias_op_t os_logbias;
zfs_cache_type_t os_primary_cache;
zfs_cache_type_t os_secondary_cache;
zfs_prefetch_type_t os_prefetch;
zfs_sync_type_t os_sync;
zfs_direct_t os_direct;
zfs_redundant_metadata_type_t os_redundant_metadata;
uint64_t os_recordsize;
/*
* The next four values are used as a cache of whatever's on disk, and
* are initialized the first time these properties are queried. Before
* being initialized with their real values, their values are
* OBJSET_PROP_UNINITIALIZED.
*/
uint64_t os_version;
uint64_t os_normalization;
uint64_t os_utf8only;
uint64_t os_casesensitivity;
/*
* The largest zpl file block allowed in special class.
* cached here instead of zfsvfs for easier access.
*/
int os_zpl_special_smallblock;
/*
* Pointer is constant; the blkptr it points to is protected by
* os_dsl_dataset->ds_bp_rwlock
*/
blkptr_t *os_rootbp;
/* no lock needed: */
struct dmu_tx *os_synctx; /* XXX sketchy */
zil_header_t os_zil_header;
multilist_t os_synced_dnodes;
uint64_t os_flags;
uint64_t os_freed_dnodes;
boolean_t os_rescan_dnodes;
boolean_t os_raw_receive;
/* os_phys_buf should be written raw next txg */
boolean_t os_next_write_raw[TXG_SIZE];
/* Protected by os_obj_lock */
kmutex_t os_obj_lock;
uint64_t os_obj_next_chunk;
/* Per-CPU next object to allocate, protected by atomic ops. */
uint64_t *os_obj_next_percpu;
int os_obj_next_percpu_len;
/* Protected by os_lock */
kmutex_t os_lock;
multilist_t os_dirty_dnodes[TXG_SIZE];
list_t os_dnodes;
list_t os_downgraded_dbufs;
/* Protects changes to DMU_{USER,GROUP,PROJECT}USED_OBJECT */
kmutex_t os_userused_lock;
/* stuff we store for the user */
kmutex_t os_user_ptr_lock;
void *os_user_ptr;
sa_os_t *os_sa;
/* kernel thread to upgrade this dataset */
kmutex_t os_upgrade_lock;
taskqid_t os_upgrade_id;
dmu_objset_upgrade_cb_t os_upgrade_cb;
boolean_t os_upgrade_exit;
int os_upgrade_status;
};
#define DMU_META_OBJSET 0
#define DMU_META_DNODE_OBJECT 0
#define DMU_OBJECT_IS_SPECIAL(obj) ((int64_t)(obj) <= 0)
#define DMU_META_DNODE(os) ((os)->os_meta_dnode.dnh_dnode)
#define DMU_USERUSED_DNODE(os) ((os)->os_userused_dnode.dnh_dnode)
#define DMU_GROUPUSED_DNODE(os) ((os)->os_groupused_dnode.dnh_dnode)
#define DMU_PROJECTUSED_DNODE(os) ((os)->os_projectused_dnode.dnh_dnode)
/* called from zpl */
int dmu_objset_hold(const char *name, const void *tag, objset_t **osp);
int dmu_objset_hold_flags(const char *name, boolean_t decrypt, const void *tag,
objset_t **osp);
int dmu_objset_own(const char *name, dmu_objset_type_t type,
boolean_t readonly, boolean_t decrypt, const void *tag, objset_t **osp);
int dmu_objset_own_obj(struct dsl_pool *dp, uint64_t obj,
dmu_objset_type_t type, boolean_t readonly, boolean_t decrypt,
const void *tag, objset_t **osp);
void dmu_objset_refresh_ownership(struct dsl_dataset *ds,
struct dsl_dataset **newds, boolean_t decrypt, const void *tag);
void dmu_objset_rele(objset_t *os, const void *tag);
void dmu_objset_rele_flags(objset_t *os, boolean_t decrypt, const void *tag);
void dmu_objset_disown(objset_t *os, boolean_t decrypt, const void *tag);
int dmu_objset_from_ds(struct dsl_dataset *ds, objset_t **osp);
void dmu_objset_stats(objset_t *os, nvlist_t *nv);
void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
uint64_t *usedobjsp, uint64_t *availobjsp);
uint64_t dmu_objset_fsid_guid(objset_t *os);
int dmu_objset_find_dp(struct dsl_pool *dp, uint64_t ddobj,
int func(struct dsl_pool *, struct dsl_dataset *, void *),
void *arg, int flags);
void dmu_objset_evict_dbufs(objset_t *os);
inode_timespec_t dmu_objset_snap_cmtime(objset_t *os);
/* called from dsl */
void dmu_objset_sync(objset_t *os, zio_t *zio, dmu_tx_t *tx);
boolean_t dmu_objset_is_dirty(objset_t *os, uint64_t txg);
objset_t *dmu_objset_create_impl_dnstats(spa_t *spa, struct dsl_dataset *ds,
blkptr_t *bp, dmu_objset_type_t type, int levels, int blksz, int ibs,
dmu_tx_t *tx);
objset_t *dmu_objset_create_impl(spa_t *spa, struct dsl_dataset *ds,
blkptr_t *bp, dmu_objset_type_t type, dmu_tx_t *tx);
int dmu_objset_open_impl(spa_t *spa, struct dsl_dataset *ds, blkptr_t *bp,
objset_t **osp);
void dmu_objset_evict(objset_t *os);
void dmu_objset_sync_done(objset_t *os, dmu_tx_t *tx);
void dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx);
boolean_t dmu_objset_userused_enabled(objset_t *os);
void dmu_objset_userspace_upgrade(objset_t *os);
boolean_t dmu_objset_userspace_present(objset_t *os);
boolean_t dmu_objset_userobjused_enabled(objset_t *os);
boolean_t dmu_objset_userobjspace_upgradable(objset_t *os);
boolean_t dmu_objset_userobjspace_present(objset_t *os);
boolean_t dmu_objset_incompatible_encryption_version(objset_t *os);
boolean_t dmu_objset_projectquota_enabled(objset_t *os);
boolean_t dmu_objset_projectquota_present(objset_t *os);
boolean_t dmu_objset_projectquota_upgradable(objset_t *os);
void dmu_objset_id_quota_upgrade(objset_t *os);
int dmu_get_file_info(objset_t *os, dmu_object_type_t bonustype,
const void *data, zfs_file_info_t *zfi);
int dmu_fsname(const char *snapname, char *buf);
void dmu_objset_evict_done(objset_t *os);
void dmu_objset_willuse_space(objset_t *os, int64_t space, dmu_tx_t *tx);
void dmu_objset_init(void);
void dmu_objset_fini(void);
#ifdef __cplusplus
}
#endif
#endif /* _SYS_DMU_OBJSET_H */
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