dbuf.c File Reference

#include <sys/zfs_context.h>
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dbuf.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dmu_tx.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/dmu_zfetch.h>
#include <sys/sa.h>
#include <sys/sa_impl.h>

Include dependency graph for dbuf.c:

Go to the source code of this file.

Defines
#define	DBUF_HASH(os, obj, level, blkid)   dbuf_hash(os, obj, level, blkid);
#define	DBUF_EQUAL(dbuf, os, obj, level, blkid)
Functions
static void	dbuf_destroy (dmu_buf_impl_t *db)
static int	dbuf_undirty (dmu_buf_impl_t *db, dmu_tx_t *tx)
	Undirty a buffer, clearing dirty records.
static void	dbuf_write (dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
	Commit a dirty buffer to disk.
static int	dbuf_cons (void *vdb, void *unused, int kmflag)
static void	dbuf_dest (void *vdb, void *unused)
static uint64_t	dbuf_hash (void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
dmu_buf_impl_t *	dbuf_find (dnode_t *dn, uint8_t level, uint64_t blkid)
static dmu_buf_impl_t *	dbuf_hash_insert (dmu_buf_impl_t *db)
	Insert an entry into the hash table.
static void	dbuf_hash_remove (dmu_buf_impl_t *db)
	Remove an entry from the hash table.
static void	dbuf_evict_user (dmu_buf_impl_t *db)
boolean_t	dbuf_is_metadata (dmu_buf_impl_t *db)
void	dbuf_evict (dmu_buf_impl_t *db)
void	dbuf_init (void)
void	dbuf_fini (void)
static void	dbuf_update_data (dmu_buf_impl_t *db)
static void	dbuf_set_data (dmu_buf_impl_t *db, arc_buf_t *buf)
	Set the dbuf's buffer to the ARC buffer, including any associated state, such as db_data.
arc_buf_t *	dbuf_loan_arcbuf (dmu_buf_impl_t *db)
	Loan out an arc_buf for read.
uint64_t	dbuf_whichblock (dnode_t *dn, uint64_t offset)
static void	dbuf_read_done (zio_t *zio, arc_buf_t *buf, void *vdb)
static void	dbuf_read_impl (dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
int	dbuf_read (dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
static void	dbuf_noread (dmu_buf_impl_t *db)
static void	dbuf_fix_old_data (dmu_buf_impl_t *db, uint64_t txg)
	This is our just-in-time copy function.
void	dbuf_unoverride (dbuf_dirty_record_t *dr)
	Signal that the dirty record is about to be re-dirtied after sync.
void	dbuf_free_range (dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
	Evict (if its unreferenced) or clear (if its referenced) any level-0 data blocks in the free range, so that any future readers will find empty blocks.
static int	dbuf_block_freeable (dmu_buf_impl_t *db)
void	dbuf_new_size (dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
void	dbuf_release_bp (dmu_buf_impl_t *db)
dbuf_dirty_record_t *	dbuf_dirty (dmu_buf_impl_t *db, dmu_tx_t *tx)
	Mark a dbuf as dirty.
void	dbuf_will_dirty (dmu_buf_impl_t *db, dmu_tx_t *tx)
void	dmu_buf_will_not_fill (dmu_buf_t *db_fake, dmu_tx_t *tx)
void	dmu_buf_will_fill (dmu_buf_t *db_fake, dmu_tx_t *tx)
void	dbuf_fill_done (dmu_buf_impl_t *db, dmu_tx_t *tx)
void	dbuf_assign_arcbuf (dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
	Directly assign a provided arc buf to a given dbuf if it's not referenced by anybody except our caller.
void	dbuf_clear (dmu_buf_impl_t *db)
	"Clear" the contents of this dbuf.
static int	dbuf_findbp (dnode_t *dn, int level, uint64_t blkid, int fail_sparse, dmu_buf_impl_t **parentp, blkptr_t **bpp)
static dmu_buf_impl_t *	dbuf_create (dnode_t *dn, uint8_t level, uint64_t blkid, dmu_buf_impl_t *parent, blkptr_t *blkptr)
static int	dbuf_do_evict (void *private)
void	dbuf_prefetch (dnode_t *dn, uint64_t blkid)
int	dbuf_hold_impl (dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse, void *tag, dmu_buf_impl_t **dbp)
	Returns with db_holds incremented, and db_mtx not held.
dmu_buf_impl_t *	dbuf_hold (dnode_t *dn, uint64_t blkid, void *tag)
dmu_buf_impl_t *	dbuf_hold_level (dnode_t *dn, int level, uint64_t blkid, void *tag)
void	dbuf_create_bonus (dnode_t *dn)
int	dbuf_spill_set_blksz (dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
void	dbuf_rm_spill (dnode_t *dn, dmu_tx_t *tx)
void	dbuf_add_ref (dmu_buf_impl_t *db, void *tag)
void	dbuf_rele (dmu_buf_impl_t *db, void *tag)
void	dbuf_rele_and_unlock (dmu_buf_impl_t *db, void *tag)
	dbuf_rele() for an already-locked dbuf.
uint64_t	dbuf_refcount (dmu_buf_impl_t *db)
void *	dmu_buf_set_user (dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
void *	dmu_buf_set_user_ie (dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
	The same as set_user, but request immediate eviction when hold count goes to zero.
void *	dmu_buf_update_user (dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr, void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
void *	dmu_buf_get_user (dmu_buf_t *db_fake)
boolean_t	dmu_buf_freeable (dmu_buf_t *dbuf)
	Tells if the given dbuf is freeable.
static void	dbuf_check_blkptr (dnode_t *dn, dmu_buf_impl_t *db)
static void	dbuf_sync_indirect (dbuf_dirty_record_t *dr, dmu_tx_t *tx)
static void	dbuf_sync_leaf (dbuf_dirty_record_t *dr, dmu_tx_t *tx)
void	dbuf_sync_list (list_t *list, dmu_tx_t *tx)
static void	dbuf_write_ready (zio_t *zio, arc_buf_t *buf, void *vdb)
static void	dbuf_write_done (zio_t *zio, arc_buf_t *buf, void *vdb)
static void	dbuf_write_nofill_ready (zio_t *zio)
static void	dbuf_write_nofill_done (zio_t *zio)
static void	dbuf_write_override_ready (zio_t *zio)
static void	dbuf_write_override_done (zio_t *zio)
Variables
static kmem_cache_t *	dbuf_cache
	Global data structures and functions for the dbuf cache.
static dbuf_hash_table_t	dbuf_hash_table
	dbuf hash table routines
static uint64_t	dbuf_hash_count
static arc_evict_func_t	dbuf_do_evict

---

Define Documentation

#define DBUF_EQUAL	(		dbuf,
			os,
			obj,
			level,
			blkid
	)

Value:

((dbuf)->db.db_object == (obj) &&               \
        (dbuf)->db_objset == (os) &&                    \
        (dbuf)->db_level == (level) &&                  \
        (dbuf)->db_blkid == (blkid))

Definition at line 101 of file dbuf.c.

#define DBUF_HASH	(		os,
			obj,
			level,
			blkid
	)		dbuf_hash(os, obj, level, blkid);

Definition at line 99 of file dbuf.c.

---

Function Documentation

void dbuf_add_ref	(	dmu_buf_impl_t *	db,
		void *	tag
	)

Definition at line 2045 of file dbuf.c.

void dbuf_assign_arcbuf	(	dmu_buf_impl_t *	db,
		arc_buf_t *	buf,
		dmu_tx_t *	tx
	)

Directly assign a provided arc buf to a given dbuf if it's not referenced by anybody except our caller.

Otherwise copy arcbuf's contents to dbuf.

Definition at line 1481 of file dbuf.c.

static int dbuf_block_freeable

(

dmu_buf_impl_t *

db

)

[static]

Definition at line 918 of file dbuf.c.

static void dbuf_check_blkptr	(	dnode_t *	dn,
		dmu_buf_impl_t *	db
	)		[static]

Definition at line 2235 of file dbuf.c.

void dbuf_clear

(

dmu_buf_impl_t *

db

)

"Clear" the contents of this dbuf.

This will mark the dbuf EVICTING and clear *most* of its references. Unfortunately, when we are not holding the dn_dbufs_mtx, we can't clear the entry in the dn_dbufs list. We have to wait until dbuf_destroy() in this case.

For callers from the DMU we will usually see:

• dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()

For the arc callback, we will usually see:

• dbuf_do_evict()->dbuf_clear();dbuf_destroy()

Sometimes, though, we will get a mix of these two:

• DMU: dbuf_clear()->arc_buf_evict()
• ARC: dbuf_do_evict()->dbuf_destroy()

Definition at line 1564 of file dbuf.c.

static int dbuf_cons	(	void *	vdb,
		void *	unused,
		int	kmflag
	)		[static]

Definition at line 52 of file dbuf.c.

static dmu_buf_impl_t* dbuf_create	(	dnode_t *	dn,
		uint8_t	level,
		uint64_t	blkid,
		dmu_buf_impl_t *	parent,
		blkptr_t *	blkptr
	)		[static]

Definition at line 1696 of file dbuf.c.

void dbuf_create_bonus

(

dnode_t *

dn

)

Definition at line 2004 of file dbuf.c.

static void dbuf_dest	(	void *	vdb,
		void *	unused
	)		[static]

Definition at line 65 of file dbuf.c.

static void dbuf_destroy

(

dmu_buf_impl_t *

db

)

[static]

Definition at line 1801 of file dbuf.c.

dbuf_dirty_record_t* dbuf_dirty	(	dmu_buf_impl_t *	db,
		dmu_tx_t *	tx
	)

Mark a dbuf as dirty.

Definition at line 1025 of file dbuf.c.

static int dbuf_do_evict

(

void *

private

)

[static]

Definition at line 1778 of file dbuf.c.

void dbuf_evict

(

dmu_buf_impl_t *

db

)

Definition at line 239 of file dbuf.c.

static void dbuf_evict_user

(

dmu_buf_impl_t *

db

)

[static]

Definition at line 207 of file dbuf.c.

void dbuf_fill_done	(	dmu_buf_impl_t *	db,
		dmu_tx_t *	tx
	)

Definition at line 1457 of file dbuf.c.

dmu_buf_impl_t* dbuf_find	(	dnode_t *	dn,
		uint8_t	level,
		uint64_t	blkid
	)

Definition at line 108 of file dbuf.c.

static int dbuf_findbp	(	dnode_t *	dn,
		int	level,
		uint64_t	blkid,
		int	fail_sparse,
		dmu_buf_impl_t **	parentp,
		blkptr_t **	bpp
	)		[static]

Definition at line 1629 of file dbuf.c.

void dbuf_fini

(

void

)

Definition at line 283 of file dbuf.c.

static void dbuf_fix_old_data	(	dmu_buf_impl_t *	db,
		uint64_t	txg
	)		[static]

This is our just-in-time copy function.

It makes a copy of buffers that have been modified in a previous transaction group, before we modify them in the current active group.

This function is used in two places: when we are dirtying a buffer for the first time in a txg, and when we are freeing a range in a dnode that includes this buffer.

Note that when we are called from dbuf_free_range() we do not put a hold on the buffer, we just traverse the active dbuf list for the dnode.

Definition at line 728 of file dbuf.c.

void dbuf_free_range	(	dnode_t *	dn,
		uint64_t	start,
		uint64_t	end,
		dmu_tx_t *	tx
	)

Evict (if its unreferenced) or clear (if its referenced) any level-0 data blocks in the free range, so that any future readers will find empty blocks.

Also, if we happen accross any level-1 dbufs in the range that have not already been marked dirty, mark them dirty so they stay in memory.

Definition at line 818 of file dbuf.c.

static uint64_t dbuf_hash	(	void *	os,
		uint64_t	obj,
		uint8_t	lvl,
		uint64_t	blkid
	)		[static]

Definition at line 81 of file dbuf.c.

static dmu_buf_impl_t* dbuf_hash_insert

(

dmu_buf_impl_t *

db

)

[static]

Insert an entry into the hash table.

If there is already an element equal to elem in the hash table, then the already existing element will be returned and the new element will not be inserted. Otherwise returns NULL.

Definition at line 139 of file dbuf.c.

static void dbuf_hash_remove

(

dmu_buf_impl_t *

db

)

[static]

Remove an entry from the hash table.

This operation will fail if there are any existing holds on the db.

Definition at line 176 of file dbuf.c.

dmu_buf_impl_t* dbuf_hold	(	dnode_t *	dn,
		uint64_t	blkid,
		void *	tag
	)

Definition at line 1988 of file dbuf.c.

int dbuf_hold_impl	(	dnode_t *	dn,
		uint8_t	level,
		uint64_t	blkid,
		int	fail_sparse,
		void *	tag,
		dmu_buf_impl_t **	dbp
	)

Returns with db_holds incremented, and db_mtx not held.

Note:

dn_struct_rwlock must be held.

Definition at line 1900 of file dbuf.c.

dmu_buf_impl_t* dbuf_hold_level	(	dnode_t *	dn,
		int	level,
		uint64_t	blkid,
		void *	tag
	)

Definition at line 1996 of file dbuf.c.

void dbuf_init

(

void

)

Definition at line 250 of file dbuf.c.

boolean_t dbuf_is_metadata

(

dmu_buf_impl_t *

db

)

Definition at line 223 of file dbuf.c.

arc_buf_t* dbuf_loan_arcbuf

(

dmu_buf_impl_t *

db

)

Loan out an arc_buf for read.

Returns:

the loaned arc_buf.

Definition at line 448 of file dbuf.c.

void dbuf_new_size	(	dmu_buf_impl_t *	db,
		int	size,
		dmu_tx_t *	tx
	)

Definition at line 948 of file dbuf.c.

static void dbuf_noread

(

dmu_buf_impl_t *

db

)

[static]

Definition at line 690 of file dbuf.c.

void dbuf_prefetch	(	dnode_t *	dn,
		uint64_t	blkid
	)

Definition at line 1845 of file dbuf.c.

int dbuf_read	(	dmu_buf_impl_t *	db,
		zio_t *	zio,
		uint32_t	flags
	)

Definition at line 600 of file dbuf.c.

static void dbuf_read_done	(	zio_t *	zio,
		arc_buf_t *	buf,
		void *	vdb
	)		[static]

Definition at line 482 of file dbuf.c.

static void dbuf_read_impl	(	dmu_buf_impl_t *	db,
		zio_t *	zio,
		uint32_t *	flags
	)		[static]

Definition at line 516 of file dbuf.c.

uint64_t dbuf_refcount

(

dmu_buf_impl_t *

db

)

Definition at line 2163 of file dbuf.c.

void dbuf_rele	(	dmu_buf_impl_t *	db,
		void *	tag
	)

Note:

If you call dbuf_rele() you had better not be referencing the dnode handle unless you have some other direct or indirect hold on the dnode. (An indirect hold is a hold on one of the dnode's dbufs, including the bonus buffer.) Without that, the dbuf_rele() could lead to a dnode_rele() followed by the dnode's parent dbuf evicting its dnode handles.

Definition at line 2062 of file dbuf.c.

void dbuf_rele_and_unlock	(	dmu_buf_impl_t *	db,
		void *	tag
	)

dbuf_rele() for an already-locked dbuf.

This is necessary to allow db_dirtycnt and db_holds to be updated atomically.

Definition at line 2073 of file dbuf.c.

void dbuf_release_bp

(

dmu_buf_impl_t *

db

)

Definition at line 1001 of file dbuf.c.

void dbuf_rm_spill	(	dnode_t *	dn,
		dmu_tx_t *	tx
	)

Definition at line 2038 of file dbuf.c.

static void dbuf_set_data	(	dmu_buf_impl_t *	db,
		arc_buf_t *	buf
	)		[static]

Set the dbuf's buffer to the ARC buffer, including any associated state, such as db_data.

Definition at line 423 of file dbuf.c.

int dbuf_spill_set_blksz	(	dmu_buf_t *	db_fake,
		uint64_t	blksz,
		dmu_tx_t *	tx
	)

Definition at line 2013 of file dbuf.c.

static void dbuf_sync_indirect	(	dbuf_dirty_record_t *	dr,
		dmu_tx_t *	tx
	)		[static]

Definition at line 2280 of file dbuf.c.

static void dbuf_sync_leaf	(	dbuf_dirty_record_t *	dr,
		dmu_tx_t *	tx
	)		[static]

Definition at line 2326 of file dbuf.c.

void dbuf_sync_list	(	list_t *	list,
		dmu_tx_t *	tx
	)

Definition at line 2466 of file dbuf.c.

static int dbuf_undirty	(	dmu_buf_impl_t *	db,
		dmu_tx_t *	tx
	)		[static]

Undirty a buffer, clearing dirty records.

Definition at line 1302 of file dbuf.c.

void dbuf_unoverride

(

dbuf_dirty_record_t *

dr

)

Signal that the dirty record is about to be re-dirtied after sync.

This function is used to notify, if necessary, that a dbuf is about to be dirtied again after having an immediate write via dmu_sync().

Definition at line 775 of file dbuf.c.

static void dbuf_update_data

(

dmu_buf_impl_t *

db

)

[static]

Definition at line 409 of file dbuf.c.

uint64_t dbuf_whichblock	(	dnode_t *	dn,
		uint64_t	offset
	)

Definition at line 471 of file dbuf.c.

void dbuf_will_dirty	(	dmu_buf_impl_t *	db,
		dmu_tx_t *	tx
	)

Definition at line 1412 of file dbuf.c.

static void dbuf_write	(	dbuf_dirty_record_t *	dr,
		arc_buf_t *	data,
		dmu_tx_t *	tx
	)		[static]

Commit a dirty buffer to disk.

Definition at line 2726 of file dbuf.c.

static void dbuf_write_done	(	zio_t *	zio,
		arc_buf_t *	buf,
		void *	vdb
	)		[static]

Definition at line 2569 of file dbuf.c.

static void dbuf_write_nofill_done

(

zio_t *

zio

)

[static]

Definition at line 2690 of file dbuf.c.

static void dbuf_write_nofill_ready

(

zio_t *

zio

)

[static]

Definition at line 2684 of file dbuf.c.

static void dbuf_write_override_done

(

zio_t *

zio

)

[static]

Definition at line 2705 of file dbuf.c.

static void dbuf_write_override_ready

(

zio_t *

zio

)

[static]

Definition at line 2696 of file dbuf.c.

static void dbuf_write_ready	(	zio_t *	zio,
		arc_buf_t *	buf,
		void *	vdb
	)		[static]

Definition at line 2493 of file dbuf.c.

boolean_t dmu_buf_freeable

(

dmu_buf_t *

dbuf

)

Tells if the given dbuf is freeable.

Definition at line 2222 of file dbuf.c.

void* dmu_buf_get_user

(

dmu_buf_t *

db

)

Returns:

The user_ptr set with dmu_buf_set_user(), or NULL if not set.

Definition at line 2213 of file dbuf.c.

void* dmu_buf_set_user	(	dmu_buf_t *	db,
		void *	user_ptr,
		void *	user_data_ptr_ptr,
		dmu_buf_evict_func_t *	evict_func
	)

Parameters:

user_ptr	For use by the user and can be obtained via dmu_buf_get_user()
user_data_ptr_ptr	Should be NULL, or a pointer to a pointer which will be set to db->db_data when the caller is allowed to access it. Note that db->db_data can change when dmu_buf_read, dmu_buf_tryupgrade, dmu_buf_will_dirty, or dmu_buf_will_fill are called. *user_data_ptr_ptr will be set to the new value when it changes.
evict_func	If not NULL, evict_func will be called when this buffer is being excised from the cache, so that the data structure pointed to by user_data_ptr_ptr can be cleaned up.

Returns:

NULL on success, or the existing user ptr if it's already been set.

dmu_evict_user() will call the evict_func for all buffers in a objset with a given pageout func.

Definition at line 2169 of file dbuf.c.

void* dmu_buf_set_user_ie	(	dmu_buf_t *	db_fake,
		void *	user_ptr,
		void *	user_data_ptr_ptr,
		dmu_buf_evict_func_t *	evict_func
	)

The same as set_user, but request immediate eviction when hold count goes to zero.

Definition at line 2177 of file dbuf.c.

void* dmu_buf_update_user	(	dmu_buf_t *	db_fake,
		void *	old_user_ptr,
		void *	user_ptr,
		void *	user_data_ptr_ptr,
		dmu_buf_evict_func_t *	evict_func
	)

Definition at line 2188 of file dbuf.c.

void dmu_buf_will_fill	(	dmu_buf_t *	db_fake,
		dmu_tx_t *	tx
	)

Definition at line 1438 of file dbuf.c.

void dmu_buf_will_not_fill	(	dmu_buf_t *	db_fake,
		dmu_tx_t *	tx
	)

Definition at line 1428 of file dbuf.c.

---

Variable Documentation

kmem_cache_t* dbuf_cache [static]

Global data structures and functions for the dbuf cache.

Definition at line 48 of file dbuf.c.

arc_evict_func_t dbuf_do_evict [static]

Definition at line 204 of file dbuf.c.

uint64_t dbuf_hash_count [static]

Definition at line 78 of file dbuf.c.

dbuf_hash_table_t dbuf_hash_table [static]

dbuf hash table routines

Definition at line 76 of file dbuf.c.