freebsd-dev/include/sys/dsl_dir.h
Richard Yao b8d06fca08 Switch KM_SLEEP to KM_PUSHPAGE
Differences between how paging is done on Solaris and Linux can cause
deadlocks if KM_SLEEP is used in any the following contexts.

  * The txg_sync thread
  * The zvol write/discard threads
  * The zpl_putpage() VFS callback

This is because KM_SLEEP will allow for direct reclaim which may result
in the VM calling back in to the filesystem or block layer to write out
pages.  If a lock is held over this operation the potential exists to
deadlock the system.  To ensure forward progress all memory allocations
in these contexts must us KM_PUSHPAGE which disables performing any I/O
to accomplish the memory allocation.

Previously, this behavior was acheived by setting PF_MEMALLOC on the
thread.  However, that resulted in unexpected side effects such as the
exhaustion of pages in ZONE_DMA.  This approach touchs more of the zfs
code, but it is more consistent with the right way to handle these cases
under Linux.

This is patch lays the ground work for being able to safely revert the
following commits which used PF_MEMALLOC:

  21ade34 Disable direct reclaim for z_wr_* threads
  cfc9a5c Fix zpl_writepage() deadlock
  eec8164 Fix ASSERTION(!dsl_pool_sync_context(tx->tx_pool))

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #726
2012-08-27 12:01:37 -07:00

168 lines
5.5 KiB
C

/*
* 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_DSL_DIR_H
#define _SYS_DSL_DIR_H
#include <sys/dmu.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_synctask.h>
#include <sys/refcount.h>
#include <sys/zfs_context.h>
#ifdef __cplusplus
extern "C" {
#endif
struct dsl_dataset;
typedef enum dd_used {
DD_USED_HEAD,
DD_USED_SNAP,
DD_USED_CHILD,
DD_USED_CHILD_RSRV,
DD_USED_REFRSRV,
DD_USED_NUM
} dd_used_t;
#define DD_FLAG_USED_BREAKDOWN (1<<0)
typedef struct dsl_dir_phys {
uint64_t dd_creation_time; /* not actually used */
uint64_t dd_head_dataset_obj;
uint64_t dd_parent_obj;
uint64_t dd_origin_obj;
uint64_t dd_child_dir_zapobj;
/*
* how much space our children are accounting for; for leaf
* datasets, == physical space used by fs + snaps
*/
uint64_t dd_used_bytes;
uint64_t dd_compressed_bytes;
uint64_t dd_uncompressed_bytes;
/* Administrative quota setting */
uint64_t dd_quota;
/* Administrative reservation setting */
uint64_t dd_reserved;
uint64_t dd_props_zapobj;
uint64_t dd_deleg_zapobj; /* dataset delegation permissions */
uint64_t dd_flags;
uint64_t dd_used_breakdown[DD_USED_NUM];
uint64_t dd_clones; /* dsl_dir objects */
uint64_t dd_pad[13]; /* pad out to 256 bytes for good measure */
} dsl_dir_phys_t;
struct dsl_dir {
/* These are immutable; no lock needed: */
uint64_t dd_object;
dsl_dir_phys_t *dd_phys;
dmu_buf_t *dd_dbuf;
dsl_pool_t *dd_pool;
/* protected by lock on pool's dp_dirty_dirs list */
txg_node_t dd_dirty_link;
/* protected by dp_config_rwlock */
dsl_dir_t *dd_parent;
/* Protected by dd_lock */
kmutex_t dd_lock;
list_t dd_prop_cbs; /* list of dsl_prop_cb_record_t's */
timestruc_t dd_snap_cmtime; /* last time snapshot namespace changed */
uint64_t dd_origin_txg;
/* gross estimate of space used by in-flight tx's */
uint64_t dd_tempreserved[TXG_SIZE];
/* amount of space we expect to write; == amount of dirty data */
int64_t dd_space_towrite[TXG_SIZE];
/* protected by dd_lock; keep at end of struct for better locality */
char dd_myname[MAXNAMELEN];
};
void dsl_dir_close(dsl_dir_t *dd, void *tag);
int dsl_dir_open(const char *name, void *tag, dsl_dir_t **, const char **tail);
int dsl_dir_open_spa(spa_t *spa, const char *name, void *tag, dsl_dir_t **,
const char **tailp);
int dsl_dir_open_obj(dsl_pool_t *dp, uint64_t ddobj,
const char *tail, void *tag, dsl_dir_t **);
void dsl_dir_name(dsl_dir_t *dd, char *buf);
int dsl_dir_namelen(dsl_dir_t *dd);
uint64_t dsl_dir_create_sync(dsl_pool_t *dp, dsl_dir_t *pds,
const char *name, dmu_tx_t *tx);
dsl_checkfunc_t dsl_dir_destroy_check;
dsl_syncfunc_t dsl_dir_destroy_sync;
void dsl_dir_stats(dsl_dir_t *dd, nvlist_t *nv);
uint64_t dsl_dir_space_available(dsl_dir_t *dd,
dsl_dir_t *ancestor, int64_t delta, int ondiskonly);
void dsl_dir_dirty(dsl_dir_t *dd, dmu_tx_t *tx);
void dsl_dir_sync(dsl_dir_t *dd, dmu_tx_t *tx);
int dsl_dir_tempreserve_space(dsl_dir_t *dd, uint64_t mem,
uint64_t asize, uint64_t fsize, uint64_t usize, void **tr_cookiep,
dmu_tx_t *tx);
void dsl_dir_tempreserve_clear(void *tr_cookie, dmu_tx_t *tx);
void dsl_dir_willuse_space(dsl_dir_t *dd, int64_t space, dmu_tx_t *tx);
void dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
int64_t used, int64_t compressed, int64_t uncompressed, dmu_tx_t *tx);
void dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
dd_used_t oldtype, dd_used_t newtype, dmu_tx_t *tx);
int dsl_dir_set_quota(const char *ddname, zprop_source_t source,
uint64_t quota);
int dsl_dir_set_reservation(const char *ddname, zprop_source_t source,
uint64_t reservation);
int dsl_dir_rename(dsl_dir_t *dd, const char *newname);
int dsl_dir_transfer_possible(dsl_dir_t *sdd, dsl_dir_t *tdd, uint64_t space);
int dsl_dir_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx);
boolean_t dsl_dir_is_clone(dsl_dir_t *dd);
void dsl_dir_new_refreservation(dsl_dir_t *dd, struct dsl_dataset *ds,
uint64_t reservation, cred_t *cr, dmu_tx_t *tx);
void dsl_dir_snap_cmtime_update(dsl_dir_t *dd);
timestruc_t dsl_dir_snap_cmtime(dsl_dir_t *dd);
/* internal reserved dir name */
#define MOS_DIR_NAME "$MOS"
#define ORIGIN_DIR_NAME "$ORIGIN"
#define XLATION_DIR_NAME "$XLATION"
#define FREE_DIR_NAME "$FREE"
#ifdef ZFS_DEBUG
#define dprintf_dd(dd, fmt, ...) do { \
if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
char *__ds_name = kmem_alloc(MAXNAMELEN + strlen(MOS_DIR_NAME) + 1, \
KM_PUSHPAGE); \
dsl_dir_name(dd, __ds_name); \
dprintf("dd=%s " fmt, __ds_name, __VA_ARGS__); \
kmem_free(__ds_name, MAXNAMELEN + strlen(MOS_DIR_NAME) + 1); \
} \
_NOTE(CONSTCOND) } while (0)
#else
#define dprintf_dd(dd, fmt, ...)
#endif
#ifdef __cplusplus
}
#endif
#endif /* _SYS_DSL_DIR_H */