d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
e3a07cd033
freebsd-nq/include/sys/zfs_vfsops.h
Brian Behlendorf c96c36fa22 Fix zsb->z_hold_mtx deadlock 
The zfs_znode_hold_enter() / zfs_znode_hold_exit() functions are used to
serialize access to a znode and its SA buffer while the object is being
created or destroyed.  This kind of locking would normally reside in the
znode itself but in this case that's impossible because the znode and SA
buffer may not yet exist.  Therefore the locking is handled externally
with an array of mutexs and AVLs trees which contain per-object locks.

In zfs_znode_hold_enter() a per-object lock is created as needed, inserted
in to the correct AVL tree and finally the per-object lock is held.  In
zfs_znode_hold_exit() the process is reversed.  The per-object lock is
released, removed from the AVL tree and destroyed if there are no waiters.

This scheme has two important properties:

1) No memory allocations are performed while holding one of the z_hold_locks.
   This ensures evict(), which can be called from direct memory reclaim, will
   never block waiting on a z_hold_locks which just happens to have hashed
   to the same index.

2) All locks used to serialize access to an object are per-object and never
   shared.  This minimizes lock contention without creating a large number
   of dedicated locks.

On the downside it does require znode_lock_t structures to be frequently
allocated and freed.  However, because these are backed by a kmem cache
and very short lived this cost is minimal.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4106
2016-01-15 15:33:45 -08:00

223 lines
8.3 KiB
C
Raw Blame History

/*
* 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.
*/
#ifndef _SYS_FS_ZFS_VFSOPS_H
#define _SYS_FS_ZFS_VFSOPS_H
#include <sys/isa_defs.h>
#include <sys/types32.h>
#include <sys/list.h>
#include <sys/vfs.h>
#include <sys/zil.h>
#include <sys/sa.h>
#include <sys/rrwlock.h>
#include <sys/zfs_ioctl.h>
#ifdef __cplusplus
extern "C" {
#endif
struct zfs_sb;
struct znode;
typedef struct zfs_mntopts {
char *z_osname; /* Objset name */
char *z_mntpoint; /* Primary mount point */
uint64_t z_xattr;
boolean_t z_readonly;
boolean_t z_do_readonly;
boolean_t z_setuid;
boolean_t z_do_setuid;
boolean_t z_exec;
boolean_t z_do_exec;
boolean_t z_devices;
boolean_t z_do_devices;
boolean_t z_do_xattr;
boolean_t z_atime;
boolean_t z_do_atime;
boolean_t z_relatime;
boolean_t z_do_relatime;
boolean_t z_nbmand;
boolean_t z_do_nbmand;
} zfs_mntopts_t;
typedef struct zfs_sb {
struct super_block *z_sb; /* generic super_block */
struct backing_dev_info z_bdi; /* generic backing dev info */
struct zfs_sb *z_parent; /* parent fs */
objset_t *z_os; /* objset reference */
zfs_mntopts_t *z_mntopts; /* passed mount options */
uint64_t z_flags; /* super_block flags */
uint64_t z_root; /* id of root znode */
uint64_t z_unlinkedobj; /* id of unlinked zapobj */
uint64_t z_max_blksz; /* maximum block size for files */
uint64_t z_fuid_obj; /* fuid table object number */
uint64_t z_fuid_size; /* fuid table size */
avl_tree_t z_fuid_idx; /* fuid tree keyed by index */
avl_tree_t z_fuid_domain; /* fuid tree keyed by domain */
krwlock_t z_fuid_lock; /* fuid lock */
boolean_t z_fuid_loaded; /* fuid tables are loaded */
boolean_t z_fuid_dirty; /* need to sync fuid table ? */
struct zfs_fuid_info *z_fuid_replay; /* fuid info for replay */
zilog_t *z_log; /* intent log pointer */
uint_t z_acl_inherit; /* acl inheritance behavior */
uint_t z_acl_type; /* type of ACL usable on this FS */
zfs_case_t z_case; /* case-sense */
boolean_t z_utf8; /* utf8-only */
int z_norm; /* normalization flags */
boolean_t z_atime; /* enable atimes mount option */
boolean_t z_relatime; /* enable relatime mount option */
boolean_t z_unmounted; /* unmounted */
rrmlock_t z_teardown_lock;
krwlock_t z_teardown_inactive_lock;
list_t z_all_znodes; /* all znodes in the fs */
uint64_t z_nr_znodes; /* number of znodes in the fs */
unsigned long z_rollback_time; /* last online rollback time */
unsigned long z_snap_defer_time; /* last snapshot unmount deferal */
kmutex_t z_znodes_lock; /* lock for z_all_znodes */
arc_prune_t *z_arc_prune; /* called by ARC to prune caches */
struct inode *z_ctldir; /* .zfs directory inode */
boolean_t z_show_ctldir; /* expose .zfs in the root dir */
boolean_t z_issnap; /* true if this is a snapshot */
boolean_t z_vscan; /* virus scan on/off */
boolean_t z_use_fuids; /* version allows fuids */
boolean_t z_replay; /* set during ZIL replay */
boolean_t z_use_sa; /* version allow system attributes */
boolean_t z_xattr_sa; /* allow xattrs to be stores as SA */
uint64_t z_version; /* ZPL version */
uint64_t z_shares_dir; /* hidden shares dir */
kmutex_t z_lock;
uint64_t z_userquota_obj;
uint64_t z_groupquota_obj;
uint64_t z_replay_eof; /* New end of file - replay only */
sa_attr_type_t *z_attr_table; /* SA attr mapping->id */
uint64_t z_hold_size; /* znode hold array size */
avl_tree_t *z_hold_trees; /* znode hold trees */
kmutex_t *z_hold_locks; /* znode hold locks */
} zfs_sb_t;
#define ZFS_SUPER_MAGIC 0x2fc12fc1
#define ZSB_XATTR 0x0001 /* Enable user xattrs */
/*
* Allow a maximum number of links. While ZFS does not internally limit
* this the inode->i_nlink member is defined as an unsigned int. To be
* safe we use 2^31-1 as the limit.
*/
#define ZFS_LINK_MAX ((1U << 31) - 1U)
/*
* Normal filesystems (those not under .zfs/snapshot) have a total
* file ID size limited to 12 bytes (including the length field) due to
* NFSv2 protocol's limitation of 32 bytes for a filehandle. For historical
* reasons, this same limit is being imposed by the Solaris NFSv3 implementation
* (although the NFSv3 protocol actually permits a maximum of 64 bytes). It
* is not possible to expand beyond 12 bytes without abandoning support
* of NFSv2.
*
* For normal filesystems, we partition up the available space as follows:
* 2 bytes fid length (required)
* 6 bytes object number (48 bits)
* 4 bytes generation number (32 bits)
*
* We reserve only 48 bits for the object number, as this is the limit
* currently defined and imposed by the DMU.
*/
typedef struct zfid_short {
uint16_t zf_len;
uint8_t zf_object[6]; /* obj[i] = obj >> (8 * i) */
uint8_t zf_gen[4]; /* gen[i] = gen >> (8 * i) */
} zfid_short_t;
/*
* Filesystems under .zfs/snapshot have a total file ID size of 22 bytes
* (including the length field). This makes files under .zfs/snapshot
* accessible by NFSv3 and NFSv4, but not NFSv2.
*
* For files under .zfs/snapshot, we partition up the available space
* as follows:
* 2 bytes fid length (required)
* 6 bytes object number (48 bits)
* 4 bytes generation number (32 bits)
* 6 bytes objset id (48 bits)
* 4 bytes currently just zero (32 bits)
*
* We reserve only 48 bits for the object number and objset id, as these are
* the limits currently defined and imposed by the DMU.
*/
typedef struct zfid_long {
zfid_short_t z_fid;
uint8_t zf_setid[6]; /* obj[i] = obj >> (8 * i) */
uint8_t zf_setgen[4]; /* gen[i] = gen >> (8 * i) */
} zfid_long_t;
#define SHORT_FID_LEN (sizeof (zfid_short_t) - sizeof (uint16_t))
#define LONG_FID_LEN (sizeof (zfid_long_t) - sizeof (uint16_t))
extern uint_t zfs_fsyncer_key;
extern int zfs_suspend_fs(zfs_sb_t *zsb);
extern int zfs_resume_fs(zfs_sb_t *zsb, const char *osname);
extern int zfs_userspace_one(zfs_sb_t *zsb, zfs_userquota_prop_t type,
const char *domain, uint64_t rid, uint64_t *valuep);
extern int zfs_userspace_many(zfs_sb_t *zsb, zfs_userquota_prop_t type,
uint64_t *cookiep, void *vbuf, uint64_t *bufsizep);
extern int zfs_set_userquota(zfs_sb_t *zsb, zfs_userquota_prop_t type,
const char *domain, uint64_t rid, uint64_t quota);
extern boolean_t zfs_owner_overquota(zfs_sb_t *zsb, struct znode *,
boolean_t isgroup);
extern boolean_t zfs_fuid_overquota(zfs_sb_t *zsb, boolean_t isgroup,
uint64_t fuid);
extern int zfs_set_version(zfs_sb_t *zsb, uint64_t newvers);
extern int zfs_get_zplprop(objset_t *os, zfs_prop_t prop,
uint64_t *value);
extern zfs_mntopts_t *zfs_mntopts_alloc(void);
extern void zfs_mntopts_free(zfs_mntopts_t *zmo);
extern int zfs_sb_create(const char *name, zfs_mntopts_t *zmo,
zfs_sb_t **zsbp);
extern int zfs_sb_setup(zfs_sb_t *zsb, boolean_t mounting);
extern void zfs_sb_free(zfs_sb_t *zsb);
extern int zfs_sb_prune(struct super_block *sb, unsigned long nr_to_scan,
int *objects);
extern int zfs_sb_teardown(zfs_sb_t *zsb, boolean_t unmounting);
extern int zfs_check_global_label(const char *dsname, const char *hexsl);
extern boolean_t zfs_is_readonly(zfs_sb_t *zsb);
extern int zfs_register_callbacks(zfs_sb_t *zsb);
extern void zfs_unregister_callbacks(zfs_sb_t *zsb);
extern int zfs_domount(struct super_block *sb, zfs_mntopts_t *zmo, int silent);
extern void zfs_preumount(struct super_block *sb);
extern int zfs_umount(struct super_block *sb);
extern int zfs_remount(struct super_block *sb, int *flags, zfs_mntopts_t *zmo);
extern int zfs_root(zfs_sb_t *zsb, struct inode **ipp);
extern int zfs_statvfs(struct dentry *dentry, struct kstatfs *statp);
extern int zfs_vget(struct super_block *sb, struct inode **ipp, fid_t *fidp);
#ifdef __cplusplus
}
#endif
#endif /* _SYS_FS_ZFS_VFSOPS_H */
Reference in New Issue View Git Blame Copy Permalink