mirror_zfs/include/sys/zfs_sa.h

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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 2010 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _SYS_ZFS_SA_H
#define _SYS_ZFS_SA_H
#ifdef _KERNEL
#include <sys/types32.h>
#include <sys/list.h>
#include <sys/dmu.h>
#include <sys/zfs_acl.h>
#include <sys/zfs_znode.h>
#include <sys/sa.h>
#include <sys/zil.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
/*
* This is the list of known attributes
* to the ZPL. The values of the actual
* attributes are not defined by the order
* the enums. It is controlled by the attribute
* registration mechanism. Two different file system
* could have different numeric values for the same
* attributes. this list is only used for dereferencing
* into the table that will hold the actual numeric value.
*/
typedef enum zpl_attr {
ZPL_ATIME,
ZPL_MTIME,
ZPL_CTIME,
ZPL_CRTIME,
ZPL_GEN,
ZPL_MODE,
ZPL_SIZE,
ZPL_PARENT,
ZPL_LINKS,
ZPL_XATTR,
ZPL_RDEV,
ZPL_FLAGS,
ZPL_UID,
ZPL_GID,
ZPL_PAD,
ZPL_ZNODE_ACL,
ZPL_DACL_COUNT,
ZPL_SYMLINK,
ZPL_SCANSTAMP,
ZPL_DACL_ACES,
Implement SA based xattrs The current ZFS implementation stores xattrs on disk using a hidden directory. In this directory a file name represents the xattr name and the file contexts are the xattr binary data. This approach is very flexible and allows for arbitrarily large xattrs. However, it also suffers from a significant performance penalty. Accessing a single xattr can requires up to three disk seeks. 1) Lookup the dnode object. 2) Lookup the dnodes's xattr directory object. 3) Lookup the xattr object in the directory. To avoid this performance penalty Linux filesystems such as ext3 and xfs try to store the xattr as part of the inode on disk. When the xattr is to large to store in the inode then a single external block is allocated for them. In practice most xattrs are small and this approach works well. The addition of System Attributes (SA) to zfs provides us a clean way to make this optimization. When the dataset property 'xattr=sa' is set then xattrs will be preferentially stored as System Attributes. This allows tiny xattrs (~100 bytes) to be stored with the dnode and up to 64k of xattrs to be stored in the spill block. If additional xattr space is required, which is unlikely under Linux, they will be stored using the traditional directory approach. This optimization results in roughly a 3x performance improvement when accessing xattrs which brings zfs roughly to parity with ext4 and xfs (see table below). When multiple xattrs are stored per-file the performance improvements are even greater because all of the xattrs stored in the spill block will be cached. However, by default SA based xattrs are disabled in the Linux port to maximize compatibility with other implementations. If you do enable SA based xattrs then they will not be visible on platforms which do not support this feature. ---------------------------------------------------------------------- Time in seconds to get/set one xattr of N bytes on 100,000 files ------+--------------------------------+------------------------------ | setxattr | getxattr bytes | ext4 xfs zfs-dir zfs-sa | ext4 xfs zfs-dir zfs-sa ------+--------------------------------+------------------------------ 1 | 2.33 31.88 21.50 4.57 | 2.35 2.64 6.29 2.43 32 | 2.79 30.68 21.98 4.60 | 2.44 2.59 6.78 2.48 256 | 3.25 31.99 21.36 5.92 | 2.32 2.71 6.22 3.14 1024 | 3.30 32.61 22.83 8.45 | 2.40 2.79 6.24 3.27 4096 | 3.57 317.46 22.52 10.73 | 2.78 28.62 6.90 3.94 16384 | n/a 2342.39 34.30 19.20 | n/a 45.44 145.90 7.55 65536 | n/a 2941.39 128.15 131.32* | n/a 141.92 256.85 262.12* Legend: * ext4 - Stock RHEL6.1 ext4 mounted with '-o user_xattr'. * xfs - Stock RHEL6.1 xfs mounted with default options. * zfs-dir - Directory based xattrs only. * zfs-sa - Prefer SAs but spill in to directories as needed, a trailing * indicates overflow in to directories occured. NOTE: Ext4 supports 4096 bytes of xattr name/value pairs per file. NOTE: XFS and ZFS have no limit on xattr name/value pairs per file. NOTE: Linux limits individual name/value pairs to 65536 bytes. NOTE: All setattr/getattr's were done after dropping the cache. NOTE: All tests were run against a single hard drive. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #443
2011-10-25 03:55:20 +04:00
ZPL_DXATTR,
Project Quota on ZFS Project quota is a new ZFS system space/object usage accounting and enforcement mechanism. Similar as user/group quota, project quota is another dimension of system quota. It bases on the new object attribute - project ID. Project ID is a numerical value to indicate to which project an object belongs. An object only can belong to one project though you (the object owner or privileged user) can change the object project ID via 'chattr -p' or 'zfs project [-s] -p' explicitly. The object also can inherit the project ID from its parent when created if the parent has the project inherit flag (that can be set via 'chattr +P' or 'zfs project -s [-p]'). By accounting the spaces/objects belong to the same project, we can know how many spaces/objects used by the project. And if we set the upper limit then we can control the spaces/objects that are consumed by such project. It is useful when multiple groups and users cooperate for the same project, or a user/group needs to participate in multiple projects. Support the following commands and functionalities: zfs set projectquota@project zfs set projectobjquota@project zfs get projectquota@project zfs get projectobjquota@project zfs get projectused@project zfs get projectobjused@project zfs projectspace zfs allow projectquota zfs allow projectobjquota zfs allow projectused zfs allow projectobjused zfs unallow projectquota zfs unallow projectobjquota zfs unallow projectused zfs unallow projectobjused chattr +/-P chattr -p project_id lsattr -p This patch also supports tree quota based on the project quota via "zfs project" commands set as following: zfs project [-d|-r] <file|directory ...> zfs project -C [-k] [-r] <file|directory ...> zfs project -c [-0] [-d|-r] [-p id] <file|directory ...> zfs project [-p id] [-r] [-s] <file|directory ...> For "df [-i] $DIR" command, if we set INHERIT (project ID) flag on the $DIR, then the proejct [obj]quota and [obj]used values for the $DIR's project ID will be shown as the total/free (avail) resource. Keep the same behavior as EXT4/XFS does. Reviewed-by: Andreas Dilger <andreas.dilger@intel.com> Reviewed-by Ned Bass <bass6@llnl.gov> Reviewed-by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Fan Yong <fan.yong@intel.com> TEST_ZIMPORT_POOLS="zol-0.6.1 zol-0.6.2 master" Change-Id: Ib4f0544602e03fb61fd46a849d7ba51a6005693c Closes #6290
2018-02-14 01:54:54 +03:00
ZPL_PROJID,
ZPL_END
} zpl_attr_t;
#define ZFS_OLD_ZNODE_PHYS_SIZE 0x108
#define ZFS_SA_BASE_ATTR_SIZE (ZFS_OLD_ZNODE_PHYS_SIZE - \
sizeof (zfs_acl_phys_t))
#define SA_MODE_OFFSET 0
#define SA_SIZE_OFFSET 8
#define SA_GEN_OFFSET 16
#define SA_UID_OFFSET 24
#define SA_GID_OFFSET 32
#define SA_PARENT_OFFSET 40
Project Quota on ZFS Project quota is a new ZFS system space/object usage accounting and enforcement mechanism. Similar as user/group quota, project quota is another dimension of system quota. It bases on the new object attribute - project ID. Project ID is a numerical value to indicate to which project an object belongs. An object only can belong to one project though you (the object owner or privileged user) can change the object project ID via 'chattr -p' or 'zfs project [-s] -p' explicitly. The object also can inherit the project ID from its parent when created if the parent has the project inherit flag (that can be set via 'chattr +P' or 'zfs project -s [-p]'). By accounting the spaces/objects belong to the same project, we can know how many spaces/objects used by the project. And if we set the upper limit then we can control the spaces/objects that are consumed by such project. It is useful when multiple groups and users cooperate for the same project, or a user/group needs to participate in multiple projects. Support the following commands and functionalities: zfs set projectquota@project zfs set projectobjquota@project zfs get projectquota@project zfs get projectobjquota@project zfs get projectused@project zfs get projectobjused@project zfs projectspace zfs allow projectquota zfs allow projectobjquota zfs allow projectused zfs allow projectobjused zfs unallow projectquota zfs unallow projectobjquota zfs unallow projectused zfs unallow projectobjused chattr +/-P chattr -p project_id lsattr -p This patch also supports tree quota based on the project quota via "zfs project" commands set as following: zfs project [-d|-r] <file|directory ...> zfs project -C [-k] [-r] <file|directory ...> zfs project -c [-0] [-d|-r] [-p id] <file|directory ...> zfs project [-p id] [-r] [-s] <file|directory ...> For "df [-i] $DIR" command, if we set INHERIT (project ID) flag on the $DIR, then the proejct [obj]quota and [obj]used values for the $DIR's project ID will be shown as the total/free (avail) resource. Keep the same behavior as EXT4/XFS does. Reviewed-by: Andreas Dilger <andreas.dilger@intel.com> Reviewed-by Ned Bass <bass6@llnl.gov> Reviewed-by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Fan Yong <fan.yong@intel.com> TEST_ZIMPORT_POOLS="zol-0.6.1 zol-0.6.2 master" Change-Id: Ib4f0544602e03fb61fd46a849d7ba51a6005693c Closes #6290
2018-02-14 01:54:54 +03:00
#define SA_FLAGS_OFFSET 48
#define SA_PROJID_OFFSET 128
extern sa_attr_reg_t zfs_attr_table[ZPL_END + 1];
extern sa_attr_reg_t zfs_legacy_attr_table[ZPL_END + 1];
/*
* This is a deprecated data structure that only exists for
* dealing with file systems create prior to ZPL version 5.
*/
typedef struct znode_phys {
uint64_t zp_atime[2]; /* 0 - last file access time */
uint64_t zp_mtime[2]; /* 16 - last file modification time */
uint64_t zp_ctime[2]; /* 32 - last file change time */
uint64_t zp_crtime[2]; /* 48 - creation time */
uint64_t zp_gen; /* 64 - generation (txg of creation) */
uint64_t zp_mode; /* 72 - file mode bits */
uint64_t zp_size; /* 80 - size of file */
uint64_t zp_parent; /* 88 - directory parent (`..') */
uint64_t zp_links; /* 96 - number of links to file */
uint64_t zp_xattr; /* 104 - DMU object for xattrs */
uint64_t zp_rdev; /* 112 - dev_t for VBLK & VCHR files */
uint64_t zp_flags; /* 120 - persistent flags */
uint64_t zp_uid; /* 128 - file owner */
uint64_t zp_gid; /* 136 - owning group */
uint64_t zp_zap; /* 144 - extra attributes */
uint64_t zp_pad[3]; /* 152 - future */
zfs_acl_phys_t zp_acl; /* 176 - 263 ACL */
/*
* Data may pad out any remaining bytes in the znode buffer, eg:
*
* |<---------------------- dnode_phys (512) ------------------------>|
* |<-- dnode (192) --->|<----------- "bonus" buffer (320) ---------->|
* |<---- znode (264) ---->|<---- data (56) ---->|
*
* At present, we use this space for the following:
* - symbolic links
* - 32-byte anti-virus scanstamp (regular files only)
*/
} znode_phys_t;
#ifdef _KERNEL
Implement SA based xattrs The current ZFS implementation stores xattrs on disk using a hidden directory. In this directory a file name represents the xattr name and the file contexts are the xattr binary data. This approach is very flexible and allows for arbitrarily large xattrs. However, it also suffers from a significant performance penalty. Accessing a single xattr can requires up to three disk seeks. 1) Lookup the dnode object. 2) Lookup the dnodes's xattr directory object. 3) Lookup the xattr object in the directory. To avoid this performance penalty Linux filesystems such as ext3 and xfs try to store the xattr as part of the inode on disk. When the xattr is to large to store in the inode then a single external block is allocated for them. In practice most xattrs are small and this approach works well. The addition of System Attributes (SA) to zfs provides us a clean way to make this optimization. When the dataset property 'xattr=sa' is set then xattrs will be preferentially stored as System Attributes. This allows tiny xattrs (~100 bytes) to be stored with the dnode and up to 64k of xattrs to be stored in the spill block. If additional xattr space is required, which is unlikely under Linux, they will be stored using the traditional directory approach. This optimization results in roughly a 3x performance improvement when accessing xattrs which brings zfs roughly to parity with ext4 and xfs (see table below). When multiple xattrs are stored per-file the performance improvements are even greater because all of the xattrs stored in the spill block will be cached. However, by default SA based xattrs are disabled in the Linux port to maximize compatibility with other implementations. If you do enable SA based xattrs then they will not be visible on platforms which do not support this feature. ---------------------------------------------------------------------- Time in seconds to get/set one xattr of N bytes on 100,000 files ------+--------------------------------+------------------------------ | setxattr | getxattr bytes | ext4 xfs zfs-dir zfs-sa | ext4 xfs zfs-dir zfs-sa ------+--------------------------------+------------------------------ 1 | 2.33 31.88 21.50 4.57 | 2.35 2.64 6.29 2.43 32 | 2.79 30.68 21.98 4.60 | 2.44 2.59 6.78 2.48 256 | 3.25 31.99 21.36 5.92 | 2.32 2.71 6.22 3.14 1024 | 3.30 32.61 22.83 8.45 | 2.40 2.79 6.24 3.27 4096 | 3.57 317.46 22.52 10.73 | 2.78 28.62 6.90 3.94 16384 | n/a 2342.39 34.30 19.20 | n/a 45.44 145.90 7.55 65536 | n/a 2941.39 128.15 131.32* | n/a 141.92 256.85 262.12* Legend: * ext4 - Stock RHEL6.1 ext4 mounted with '-o user_xattr'. * xfs - Stock RHEL6.1 xfs mounted with default options. * zfs-dir - Directory based xattrs only. * zfs-sa - Prefer SAs but spill in to directories as needed, a trailing * indicates overflow in to directories occured. NOTE: Ext4 supports 4096 bytes of xattr name/value pairs per file. NOTE: XFS and ZFS have no limit on xattr name/value pairs per file. NOTE: Linux limits individual name/value pairs to 65536 bytes. NOTE: All setattr/getattr's were done after dropping the cache. NOTE: All tests were run against a single hard drive. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #443
2011-10-25 03:55:20 +04:00
#define DXATTR_MAX_ENTRY_SIZE (32768)
Illumos 5027 - zfs large block support 5027 zfs large block support Reviewed by: Alek Pinchuk <pinchuk.alek@gmail.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Josef 'Jeff' Sipek <josef.sipek@nexenta.com> Reviewed by: Richard Elling <richard.elling@richardelling.com> Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com> Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Dan McDonald <danmcd@omniti.com> References: https://www.illumos.org/issues/5027 https://github.com/illumos/illumos-gate/commit/b515258 Porting Notes: * Included in this patch is a tiny ISP2() cleanup in zio_init() from Illumos 5255. * Unlike the upstream Illumos commit this patch does not impose an arbitrary 128K block size limit on volumes. Volumes, like filesystems, are limited by the zfs_max_recordsize=1M module option. * By default the maximum record size is limited to 1M by the module option zfs_max_recordsize. This value may be safely increased up to 16M which is the largest block size supported by the on-disk format. At the moment, 1M blocks clearly offer a significant performance improvement but the benefits of going beyond this for the majority of workloads are less clear. * The illumos version of this patch increased DMU_MAX_ACCESS to 32M. This was determined not to be large enough when using 16M blocks because the zfs_make_xattrdir() function will fail (EFBIG) when assigning a TX. This was immediately observed under Linux because all newly created files must have a security xattr created and that was failing. Therefore, we've set DMU_MAX_ACCESS to 64M. * On 32-bit platforms a hard limit of 1M is set for blocks due to the limited virtual address space. We should be able to relax this one the ABD patches are merged. Ported-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #354
2014-11-03 23:15:08 +03:00
#define DXATTR_MAX_SA_SIZE (SPA_OLD_MAXBLOCKSIZE >> 1)
Implement SA based xattrs The current ZFS implementation stores xattrs on disk using a hidden directory. In this directory a file name represents the xattr name and the file contexts are the xattr binary data. This approach is very flexible and allows for arbitrarily large xattrs. However, it also suffers from a significant performance penalty. Accessing a single xattr can requires up to three disk seeks. 1) Lookup the dnode object. 2) Lookup the dnodes's xattr directory object. 3) Lookup the xattr object in the directory. To avoid this performance penalty Linux filesystems such as ext3 and xfs try to store the xattr as part of the inode on disk. When the xattr is to large to store in the inode then a single external block is allocated for them. In practice most xattrs are small and this approach works well. The addition of System Attributes (SA) to zfs provides us a clean way to make this optimization. When the dataset property 'xattr=sa' is set then xattrs will be preferentially stored as System Attributes. This allows tiny xattrs (~100 bytes) to be stored with the dnode and up to 64k of xattrs to be stored in the spill block. If additional xattr space is required, which is unlikely under Linux, they will be stored using the traditional directory approach. This optimization results in roughly a 3x performance improvement when accessing xattrs which brings zfs roughly to parity with ext4 and xfs (see table below). When multiple xattrs are stored per-file the performance improvements are even greater because all of the xattrs stored in the spill block will be cached. However, by default SA based xattrs are disabled in the Linux port to maximize compatibility with other implementations. If you do enable SA based xattrs then they will not be visible on platforms which do not support this feature. ---------------------------------------------------------------------- Time in seconds to get/set one xattr of N bytes on 100,000 files ------+--------------------------------+------------------------------ | setxattr | getxattr bytes | ext4 xfs zfs-dir zfs-sa | ext4 xfs zfs-dir zfs-sa ------+--------------------------------+------------------------------ 1 | 2.33 31.88 21.50 4.57 | 2.35 2.64 6.29 2.43 32 | 2.79 30.68 21.98 4.60 | 2.44 2.59 6.78 2.48 256 | 3.25 31.99 21.36 5.92 | 2.32 2.71 6.22 3.14 1024 | 3.30 32.61 22.83 8.45 | 2.40 2.79 6.24 3.27 4096 | 3.57 317.46 22.52 10.73 | 2.78 28.62 6.90 3.94 16384 | n/a 2342.39 34.30 19.20 | n/a 45.44 145.90 7.55 65536 | n/a 2941.39 128.15 131.32* | n/a 141.92 256.85 262.12* Legend: * ext4 - Stock RHEL6.1 ext4 mounted with '-o user_xattr'. * xfs - Stock RHEL6.1 xfs mounted with default options. * zfs-dir - Directory based xattrs only. * zfs-sa - Prefer SAs but spill in to directories as needed, a trailing * indicates overflow in to directories occured. NOTE: Ext4 supports 4096 bytes of xattr name/value pairs per file. NOTE: XFS and ZFS have no limit on xattr name/value pairs per file. NOTE: Linux limits individual name/value pairs to 65536 bytes. NOTE: All setattr/getattr's were done after dropping the cache. NOTE: All tests were run against a single hard drive. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #443
2011-10-25 03:55:20 +04:00
int zfs_sa_readlink(struct znode *, zfs_uio_t *);
void zfs_sa_symlink(struct znode *, char *link, int len, dmu_tx_t *);
void zfs_sa_get_scanstamp(struct znode *, xvattr_t *);
void zfs_sa_set_scanstamp(struct znode *, xvattr_t *, dmu_tx_t *);
Implement SA based xattrs The current ZFS implementation stores xattrs on disk using a hidden directory. In this directory a file name represents the xattr name and the file contexts are the xattr binary data. This approach is very flexible and allows for arbitrarily large xattrs. However, it also suffers from a significant performance penalty. Accessing a single xattr can requires up to three disk seeks. 1) Lookup the dnode object. 2) Lookup the dnodes's xattr directory object. 3) Lookup the xattr object in the directory. To avoid this performance penalty Linux filesystems such as ext3 and xfs try to store the xattr as part of the inode on disk. When the xattr is to large to store in the inode then a single external block is allocated for them. In practice most xattrs are small and this approach works well. The addition of System Attributes (SA) to zfs provides us a clean way to make this optimization. When the dataset property 'xattr=sa' is set then xattrs will be preferentially stored as System Attributes. This allows tiny xattrs (~100 bytes) to be stored with the dnode and up to 64k of xattrs to be stored in the spill block. If additional xattr space is required, which is unlikely under Linux, they will be stored using the traditional directory approach. This optimization results in roughly a 3x performance improvement when accessing xattrs which brings zfs roughly to parity with ext4 and xfs (see table below). When multiple xattrs are stored per-file the performance improvements are even greater because all of the xattrs stored in the spill block will be cached. However, by default SA based xattrs are disabled in the Linux port to maximize compatibility with other implementations. If you do enable SA based xattrs then they will not be visible on platforms which do not support this feature. ---------------------------------------------------------------------- Time in seconds to get/set one xattr of N bytes on 100,000 files ------+--------------------------------+------------------------------ | setxattr | getxattr bytes | ext4 xfs zfs-dir zfs-sa | ext4 xfs zfs-dir zfs-sa ------+--------------------------------+------------------------------ 1 | 2.33 31.88 21.50 4.57 | 2.35 2.64 6.29 2.43 32 | 2.79 30.68 21.98 4.60 | 2.44 2.59 6.78 2.48 256 | 3.25 31.99 21.36 5.92 | 2.32 2.71 6.22 3.14 1024 | 3.30 32.61 22.83 8.45 | 2.40 2.79 6.24 3.27 4096 | 3.57 317.46 22.52 10.73 | 2.78 28.62 6.90 3.94 16384 | n/a 2342.39 34.30 19.20 | n/a 45.44 145.90 7.55 65536 | n/a 2941.39 128.15 131.32* | n/a 141.92 256.85 262.12* Legend: * ext4 - Stock RHEL6.1 ext4 mounted with '-o user_xattr'. * xfs - Stock RHEL6.1 xfs mounted with default options. * zfs-dir - Directory based xattrs only. * zfs-sa - Prefer SAs but spill in to directories as needed, a trailing * indicates overflow in to directories occured. NOTE: Ext4 supports 4096 bytes of xattr name/value pairs per file. NOTE: XFS and ZFS have no limit on xattr name/value pairs per file. NOTE: Linux limits individual name/value pairs to 65536 bytes. NOTE: All setattr/getattr's were done after dropping the cache. NOTE: All tests were run against a single hard drive. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #443
2011-10-25 03:55:20 +04:00
int zfs_sa_get_xattr(struct znode *);
int zfs_sa_set_xattr(struct znode *);
void zfs_sa_upgrade(struct sa_handle *, dmu_tx_t *);
void zfs_sa_upgrade_txholds(dmu_tx_t *, struct znode *);
Implement SA based xattrs The current ZFS implementation stores xattrs on disk using a hidden directory. In this directory a file name represents the xattr name and the file contexts are the xattr binary data. This approach is very flexible and allows for arbitrarily large xattrs. However, it also suffers from a significant performance penalty. Accessing a single xattr can requires up to three disk seeks. 1) Lookup the dnode object. 2) Lookup the dnodes's xattr directory object. 3) Lookup the xattr object in the directory. To avoid this performance penalty Linux filesystems such as ext3 and xfs try to store the xattr as part of the inode on disk. When the xattr is to large to store in the inode then a single external block is allocated for them. In practice most xattrs are small and this approach works well. The addition of System Attributes (SA) to zfs provides us a clean way to make this optimization. When the dataset property 'xattr=sa' is set then xattrs will be preferentially stored as System Attributes. This allows tiny xattrs (~100 bytes) to be stored with the dnode and up to 64k of xattrs to be stored in the spill block. If additional xattr space is required, which is unlikely under Linux, they will be stored using the traditional directory approach. This optimization results in roughly a 3x performance improvement when accessing xattrs which brings zfs roughly to parity with ext4 and xfs (see table below). When multiple xattrs are stored per-file the performance improvements are even greater because all of the xattrs stored in the spill block will be cached. However, by default SA based xattrs are disabled in the Linux port to maximize compatibility with other implementations. If you do enable SA based xattrs then they will not be visible on platforms which do not support this feature. ---------------------------------------------------------------------- Time in seconds to get/set one xattr of N bytes on 100,000 files ------+--------------------------------+------------------------------ | setxattr | getxattr bytes | ext4 xfs zfs-dir zfs-sa | ext4 xfs zfs-dir zfs-sa ------+--------------------------------+------------------------------ 1 | 2.33 31.88 21.50 4.57 | 2.35 2.64 6.29 2.43 32 | 2.79 30.68 21.98 4.60 | 2.44 2.59 6.78 2.48 256 | 3.25 31.99 21.36 5.92 | 2.32 2.71 6.22 3.14 1024 | 3.30 32.61 22.83 8.45 | 2.40 2.79 6.24 3.27 4096 | 3.57 317.46 22.52 10.73 | 2.78 28.62 6.90 3.94 16384 | n/a 2342.39 34.30 19.20 | n/a 45.44 145.90 7.55 65536 | n/a 2941.39 128.15 131.32* | n/a 141.92 256.85 262.12* Legend: * ext4 - Stock RHEL6.1 ext4 mounted with '-o user_xattr'. * xfs - Stock RHEL6.1 xfs mounted with default options. * zfs-dir - Directory based xattrs only. * zfs-sa - Prefer SAs but spill in to directories as needed, a trailing * indicates overflow in to directories occured. NOTE: Ext4 supports 4096 bytes of xattr name/value pairs per file. NOTE: XFS and ZFS have no limit on xattr name/value pairs per file. NOTE: Linux limits individual name/value pairs to 65536 bytes. NOTE: All setattr/getattr's were done after dropping the cache. NOTE: All tests were run against a single hard drive. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #443
2011-10-25 03:55:20 +04:00
void zfs_sa_init(void);
void zfs_sa_fini(void);
#endif
#ifdef __cplusplus
}
#endif
#endif /* _SYS_ZFS_SA_H */