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Illumos 5056 - ZFS deadlock on db_mtx and dn_holds
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5056 ZFS deadlock on db_mtx and dn_holds
Author: Justin Gibbs <[email protected]>
Reviewed by: Will Andrews <[email protected]>
Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: George Wilson <[email protected]>
Approved by: Dan McDonald <[email protected]>

References:
  https://www.illumos.org/issues/5056
  illumos/illumos-gate@bc9014e

Porting Notes:

sa_handle_get_from_db():
  - the original patch includes an otherwise unmentioned fix for a
    possible usage of an uninitialised variable

dmu_objset_open_impl():
  - Under Illumos list_link_init() is the same as filling a list_node_t
    with NULLs, so they don't notice if they miss doing list_link_init()
    on a zero'd containing structure (e.g. allocated with kmem_zalloc as
    here). Under Linux, not so much: an uninitialised list_node_t goes
    "Boom!" some time later when it's used or destroyed.

dmu_objset_evict_dbufs():
  - reduce stack usage using kmem_alloc()

Ported-by: Chris Dunlop <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
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Justin T. Gibbs authored and behlendorf committed Apr 28, 2015
1 parent d683ddb commit 0c66c32
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Showing 35 changed files with 637 additions and 308 deletions.
6 changes: 3 additions & 3 deletions include/sys/dbuf.h
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_DBUF_H
Expand Down Expand Up @@ -226,9 +227,8 @@ typedef struct dmu_buf_impl {

/* Data which is unique to data (leaf) blocks: */

/* stuff we store for the user (see dmu_buf_set_user) */
void *db_user_ptr;
dmu_buf_evict_func_t *db_evict_func;
/* User callback information. */
dmu_buf_user_t *db_user;

uint8_t db_immediate_evict;
uint8_t db_freed_in_flight;
Expand Down
133 changes: 110 additions & 23 deletions include/sys/dmu.h
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2012, Joyent, Inc. All rights reserved.
* Copyright 2014 HybridCluster. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

/* Portions Copyright 2010 Robert Milkowski */
Expand All @@ -39,11 +40,9 @@
* dmu_spa.h.
*/

#include <sys/zfs_context.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>

Expand Down Expand Up @@ -288,8 +287,6 @@ typedef struct dmu_buf {
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.
*/
Expand Down Expand Up @@ -475,36 +472,126 @@ 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);

typedef void dmu_buf_evict_func_t(void *user_ptr);

/*
* A DMU buffer user object may be associated with a dbuf for the
* duration of its lifetime. This allows the user of a dbuf (client)
* to attach private data to a dbuf (e.g. in-core only data such as a
* dnode_children_t, zap_t, or zap_leaf_t) and be optionally notified
* when that dbuf has been evicted. Clients typically respond to the
* eviction notification by freeing their private data, thus ensuring
* the same lifetime for both dbuf and private data.
*
* The mapping from a dmu_buf_user_t to any client private data is the
* client's responsibility. All current consumers of the API with private
* data embed a dmu_buf_user_t as the first member of the structure for
* their private data. This allows conversions between the two types
* with a simple cast. Since the DMU buf user API never needs access
* to the private data, other strategies can be employed if necessary
* or convenient for the client (e.g. using container_of() to do the
* conversion for private data that cannot have the dmu_buf_user_t as
* its first member).
*
* Eviction callbacks are executed without the dbuf mutex held or any
* other type of mechanism to guarantee that the dbuf is still available.
* For this reason, users must assume the dbuf has already been freed
* and not reference the dbuf from the callback context.
*
* Users requesting "immediate eviction" are notified as soon as the dbuf
* is only referenced by dirty records (dirties == holds). Otherwise the
* notification occurs after eviction processing for the dbuf begins.
*/
typedef struct dmu_buf_user {
/*
* Asynchronous user eviction callback state.
*/
taskq_ent_t dbu_tqent;

/* This instance's eviction function pointer. */
dmu_buf_evict_func_t *dbu_evict_func;
#ifdef ZFS_DEBUG
/*
* Pointer to user's dbuf pointer. NULL for clients that do
* not associate a dbuf with their user data.
*
* The dbuf pointer is cleared upon eviction so as to catch
* use-after-evict bugs in clients.
*/
dmu_buf_t **dbu_clear_on_evict_dbufp;
#endif
} dmu_buf_user_t;

/*
* Initialize the given dmu_buf_user_t instance with the eviction function
* evict_func, to be called when the user is evicted.
*
* NOTE: This function should only be called once on a given dmu_buf_user_t.
* To allow enforcement of this, dbu must already be zeroed on entry.
*/
#ifdef __lint
/* Very ugly, but it beats issuing suppression directives in many Makefiles. */
extern void
dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func,
dmu_buf_t **clear_on_evict_dbufp);
#else /* __lint */
static inline void
dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func,
dmu_buf_t **clear_on_evict_dbufp)
{
ASSERT(dbu->dbu_evict_func == NULL);
ASSERT(evict_func != NULL);
dbu->dbu_evict_func = evict_func;
#ifdef ZFS_DEBUG
dbu->dbu_clear_on_evict_dbufp = clear_on_evict_dbufp;
#endif
}
#endif /* __lint */

/*
* Returns NULL on success, or the existing user ptr if it's already
* been set.
* Attach user data to a dbuf and mark it for normal (when the dbuf's
* data is cleared or its reference count goes to zero) eviction processing.
*
* user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
* Returns NULL on success, or the existing user if another user currently
* owns the buffer.
*/
void *dmu_buf_set_user(dmu_buf_t *db, dmu_buf_user_t *user);

/*
* Attach user data to a dbuf and mark it for immediate (its dirty and
* reference counts are equal) eviction processing.
*
* 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.
* Returns NULL on success, or the existing user if another user currently
* owns the buffer.
*/
void *dmu_buf_set_user_ie(dmu_buf_t *db, dmu_buf_user_t *user);

/*
* Replace the current user of a dbuf.
*
* dmu_evict_user() will call the pageout func for all buffers in a
* objset with a given pageout func.
* If given the current user of a dbuf, replaces the dbuf's user with
* "new_user" and returns the user data pointer that was replaced.
* Otherwise returns the current, and unmodified, dbuf user pointer.
*/
void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr,
dmu_buf_evict_func_t *pageout_func);
void *dmu_buf_replace_user(dmu_buf_t *db,
dmu_buf_user_t *old_user, dmu_buf_user_t *new_user);

/*
* set_user_ie is the same as set_user, but request immediate eviction
* when hold count goes to zero.
* Remove the specified user data for a DMU buffer.
*
* Returns the user that was removed on success, or the current user if
* another user currently owns the buffer.
*/
void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_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, dmu_buf_evict_func_t *pageout_func);
void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
void *dmu_buf_remove_user(dmu_buf_t *db, dmu_buf_user_t *user);

/*
* Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
* Returns the user data (dmu_buf_user_t *) associated with this dbuf.
*/
void *dmu_buf_get_user(dmu_buf_t *db);

/* Block until any in-progress dmu buf user evictions complete. */
void dmu_buf_user_evict_wait(void);

/*
* Returns the blkptr associated with this dbuf, or NULL if not set.
*/
Expand Down
14 changes: 10 additions & 4 deletions include/sys/dmu_objset.h
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

/* Portions Copyright 2010 Robert Milkowski */
Expand Down Expand Up @@ -74,22 +75,25 @@ struct objset {
arc_buf_t *os_phys_buf;
objset_phys_t *os_phys;
/*
* The following "special" dnodes have no parent and are exempt from
* dnode_move(), but they root their descendents in this objset using
* handles anyway, so that all access to dnodes from dbufs consistently
* uses handles.
* 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;
zilog_t *os_zil;

list_node_t os_evicting_node;

/* can change, under dsl_dir's locks: */
enum zio_checksum os_checksum;
enum zio_compress os_compress;
uint8_t os_copies;
enum zio_checksum os_dedup_checksum;
boolean_t os_dedup_verify;
boolean_t os_evicting;
zfs_logbias_op_t os_logbias;
zfs_cache_type_t os_primary_cache;
zfs_cache_type_t os_secondary_cache;
Expand Down Expand Up @@ -168,6 +172,8 @@ int dmu_objset_userspace_upgrade(objset_t *os);
boolean_t dmu_objset_userspace_present(objset_t *os);
int dmu_fsname(const char *snapname, char *buf);

void dmu_objset_evict_done(objset_t *os);

void dmu_objset_init(void);
void dmu_objset_fini(void);

Expand Down
4 changes: 3 additions & 1 deletion include/sys/dnode.h
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_DNODE_H
Expand Down Expand Up @@ -277,6 +278,7 @@ typedef struct dnode_handle {
} dnode_handle_t;

typedef struct dnode_children {
dmu_buf_user_t dnc_dbu; /* User evict data */
size_t dnc_count; /* number of children */
dnode_handle_t dnc_children[]; /* sized dynamically */
} dnode_children_t;
Expand All @@ -287,7 +289,7 @@ typedef struct free_range {
uint64_t fr_nblks;
} free_range_t;

dnode_t *dnode_special_open(struct objset *dd, dnode_phys_t *dnp,
void dnode_special_open(struct objset *dd, dnode_phys_t *dnp,
uint64_t object, dnode_handle_t *dnh);
void dnode_special_close(dnode_handle_t *dnh);

Expand Down
10 changes: 4 additions & 6 deletions include/sys/dsl_dataset.h
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
* Copyright (c) 2013 Steven Hartland. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_DSL_DATASET_H
Expand Down Expand Up @@ -125,11 +126,14 @@ typedef struct dsl_dataset_phys {
} dsl_dataset_phys_t;

typedef struct dsl_dataset {
dmu_buf_user_t ds_dbu;

/* Immutable: */
struct dsl_dir *ds_dir;
dmu_buf_t *ds_dbuf;
uint64_t ds_object;
uint64_t ds_fsid_guid;
boolean_t ds_is_snapshot;

/* only used in syncing context, only valid for non-snapshots: */
struct dsl_dataset *ds_prev;
Expand Down Expand Up @@ -188,12 +192,6 @@ dsl_dataset_phys(dsl_dataset_t *ds)
*/
#define MAX_TAG_PREFIX_LEN 17

static inline boolean_t
dsl_dataset_is_snapshot(dsl_dataset_t *ds)
{
return (dsl_dataset_phys(ds)->ds_num_children != 0);
}

#define DS_UNIQUE_IS_ACCURATE(ds) \
((dsl_dataset_phys(ds)->ds_flags & DS_FLAG_UNIQUE_ACCURATE) != 0)

Expand Down
4 changes: 4 additions & 0 deletions include/sys/dsl_dir.h
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright (c) 2014, Joyent, Inc. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_DSL_DIR_H
Expand Down Expand Up @@ -84,6 +85,8 @@ typedef struct dsl_dir_phys {
} dsl_dir_phys_t;

struct dsl_dir {
dmu_buf_user_t dd_dbu;

/* These are immutable; no lock needed: */
uint64_t dd_object;
dsl_pool_t *dd_pool;
Expand Down Expand Up @@ -119,6 +122,7 @@ dsl_dir_phys(dsl_dir_t *dd)
}

void dsl_dir_rele(dsl_dir_t *dd, void *tag);
void dsl_dir_async_rele(dsl_dir_t *dd, void *tag);
int dsl_dir_hold(dsl_pool_t *dp, const char *name, void *tag,
dsl_dir_t **, const char **tail);
int dsl_dir_hold_obj(dsl_pool_t *dp, uint64_t ddobj,
Expand Down
1 change: 0 additions & 1 deletion include/sys/sa.h
Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,6 @@ int sa_update_from_cb(sa_handle_t *, sa_attr_type_t,
uint32_t buflen, sa_data_locator_t *, void *userdata, dmu_tx_t *);
void sa_object_info(sa_handle_t *, dmu_object_info_t *);
void sa_object_size(sa_handle_t *, uint32_t *, u_longlong_t *);
void sa_update_user(sa_handle_t *, sa_handle_t *);
void *sa_get_userdata(sa_handle_t *);
void sa_set_userp(sa_handle_t *, void *);
dmu_buf_t *sa_get_db(sa_handle_t *);
Expand Down
4 changes: 3 additions & 1 deletion include/sys/sa_impl.h
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
/*
* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_SA_IMPL_H
Expand Down Expand Up @@ -208,11 +209,12 @@ typedef enum sa_data_op {
*/

struct sa_handle {
dmu_buf_user_t sa_dbu;
kmutex_t sa_lock;
dmu_buf_t *sa_bonus;
dmu_buf_t *sa_spill;
objset_t *sa_os;
void *sa_userp;
void *sa_userp;
sa_idx_tab_t *sa_bonus_tab; /* idx of bonus */
sa_idx_tab_t *sa_spill_tab; /* only present if spill activated */
};
Expand Down
5 changes: 5 additions & 0 deletions include/sys/spa.h
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2011, 2014 by Delphix. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/

#ifndef _SYS_SPA_H
Expand Down Expand Up @@ -680,6 +681,7 @@ extern spa_t *spa_next(spa_t *prev);
/* Refcount functions */
extern void spa_open_ref(spa_t *spa, void *tag);
extern void spa_close(spa_t *spa, void *tag);
extern void spa_async_close(spa_t *spa, void *tag);
extern boolean_t spa_refcount_zero(spa_t *spa);

#define SCL_NONE 0x00
Expand Down Expand Up @@ -789,6 +791,9 @@ extern uint64_t spa_version(spa_t *spa);
extern boolean_t spa_deflate(spa_t *spa);
extern metaslab_class_t *spa_normal_class(spa_t *spa);
extern metaslab_class_t *spa_log_class(spa_t *spa);
extern void spa_evicting_os_register(spa_t *, objset_t *os);
extern void spa_evicting_os_deregister(spa_t *, objset_t *os);
extern void spa_evicting_os_wait(spa_t *spa);
extern int spa_max_replication(spa_t *spa);
extern int spa_prev_software_version(spa_t *spa);
extern uint8_t spa_get_failmode(spa_t *spa);
Expand Down
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