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dfa4d3d986
mirror_zfs/module/zfs/dmu.c
Serapheim Dimitropoulos dfa4d3d986 dmu_tx_wait() hang likely due to cv_signal() in dsl_pool_dirty_delta() 
Even though the bug's writeup (Github issue #9136) is very detailed,
we still don't know exactly how we got to that state, thus I wasn't
able to reproduce the bug. That said, we can make an educated guess
combining the information on filled issue with the code.

From the fact that `dp_dirty_total` was 0 (which is less than
`zfs_dirty_data_max`) we know that there was one thread that set it to
0 and then signaled one of the waiters of `dp_spaceavail_cv` [see
`dsl_pool_dirty_delta()` which is also the only place that
`dp_dirty_total` is changed].  Thus, the only logical explaination
then for the bug being hit is that the waiter that just got awaken
didn't go through `dsl_pool_dirty_data()`. Given that this function
is only called by `dsl_pool_dirty_space()` or `dsl_pool_undirty_space()`
I can only think of two possible ways of the above scenario happening:

[1] The waiter didn't call into any of the two functions - which I
    find highly unlikely (i.e. why wait on `dp_spaceavail_cv` to begin
    with?).
[2] The waiter did call in one of the above function but it passed 0 as
    the space/delta to be dirtied (or undirtied) and then the callee
    returned immediately (e.g both `dsl_pool_dirty_space()` and
    `dsl_pool_undirty_space()` return immediately when space is 0).

In any case and no matter how we got there, the easy fix would be to
just broadcast to all waiters whenever `dp_dirty_total` hits 0. That
said and given that we've never hit this before, it would make sense
to think more on why the above situation occured.

Attempting to mimic what Prakash was doing in the issue filed, I
created a dataset with `sync=always` and started doing contiguous
writes in a file within that dataset. I observed with DTrace that even
though we update the pool's dirty data accounting when we would dirty
stuff, the accounting wouldn't be decremented incrementally as we were
done with the ZIOs of those writes (the reason being that
`dbuf_write_physdone()` isn't be called as we go through the override
code paths, and thus `dsl_pool_undirty_space()` is never called). As a
result we'd have to wait until we get to `dsl_pool_sync()` where we
zero out all dirty data accounting for the pool and the current TXG's
metadata.

In addition, as Matt noted and I later verified, the same issue would
arise when using dedup.

In both cases (sync & dedup) we shouldn't have to wait until
`dsl_pool_sync()` zeros out the accounting data. According to the
comment in that part of the code, the reasons why we do the zeroing,
have nothing to do with what we observe:
````
/*
 * We have written all of the accounted dirty data, so our
 * dp_space_towrite should now be zero.  However, some seldom-used
 * code paths do not adhere to this (e.g. dbuf_undirty(), also
 * rounding error in dbuf_write_physdone).
 * Shore up the accounting of any dirtied space now.
 */
dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
````

Ideally what we want to do is to undirty in the accounting exactly what
we dirty (I use the word ideally as we can still have rounding errors).
This would make the behavior of the system more clear and predictable.

Another interesting issue that I observed with DTrace was that we
wouldn't update any of the pool's dirty data accounting whenever we
would dirty and/or undirty MOS data. In addition, every time we would
change the size of a dbuf through `dbuf_new_size()` we wouldn't update
the accounted space dirtied in the appropriate dirty record, so when
ZIOs are done we would undirty less that we dirtied from the pool's
accounting point of view.

For the first two issues observed (sync & dedup) this patch ensures
that we still update the pool's accounting when we undirty data,
regardless of the write being physical or not.

For changes in the MOS, we first ensure to zero out the pool's dirty
data accounting in `dsl_pool_sync()` after we synced the MOS. Then we
can go ahead and enable the update of the pool's dirty data accounting
wheneve we change MOS data.

Another fix is that we now update the accounting explicitly for
counting errors in `dbuf_write_done()`.

Finally, `dbuf_new_size()` updates the accounted space of the
appropriate dirty record correctly now.

The problem is that we still don't know how the bug came up in the
issue filled. That said the issues fixed seem to be very relevant, so
instead of going with the broadcasting solution right away,
I decided to leave this patch as is.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
External-issue: DLPX-47285
Closes #9137
2020-01-22 13:48:57 -08:00

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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
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*
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* 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.
* Copyright (c) 2011, 2017 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
* Copyright (c) 2016, Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
* Copyright (c) 2019 Datto Inc.
*/
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_traverse.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_synctask.h>
#include <sys/dsl_prop.h>
#include <sys/dmu_zfetch.h>
#include <sys/zfs_ioctl.h>
#include <sys/zap.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/sa.h>
#include <sys/zfeature.h>
#include <sys/abd.h>
#include <sys/trace_dmu.h>
#include <sys/zfs_rlock.h>
#ifdef _KERNEL
#include <sys/vmsystm.h>
#include <sys/zfs_znode.h>
#endif
/*
* Enable/disable nopwrite feature.
*/
int zfs_nopwrite_enabled = 1;
/*
* Tunable to control percentage of dirtied L1 blocks from frees allowed into
* one TXG. After this threshold is crossed, additional dirty blocks from frees
* will wait until the next TXG.
* A value of zero will disable this throttle.
*/
unsigned long zfs_per_txg_dirty_frees_percent = 5;
/*
* Enable/disable forcing txg sync when dirty in dmu_offset_next.
*/
int zfs_dmu_offset_next_sync = 0;
/*
* This can be used for testing, to ensure that certain actions happen
* while in the middle of a remap (which might otherwise complete too
* quickly). Used by ztest(8).
*/
int zfs_object_remap_one_indirect_delay_ms = 0;
/*
* Limit the amount we can prefetch with one call to this amount. This
* helps to limit the amount of memory that can be used by prefetching.
* Larger objects should be prefetched a bit at a time.
*/
int dmu_prefetch_max = 8 * SPA_MAXBLOCKSIZE;
const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
{DMU_BSWAP_UINT8, TRUE, FALSE, FALSE, "unallocated" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "object directory" },
{DMU_BSWAP_UINT64, TRUE, TRUE, FALSE, "object array" },
{DMU_BSWAP_UINT8, TRUE, FALSE, FALSE, "packed nvlist" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "packed nvlist size" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "bpobj" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "bpobj header" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "SPA space map header" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "SPA space map" },
{DMU_BSWAP_UINT64, TRUE, FALSE, TRUE, "ZIL intent log" },
{DMU_BSWAP_DNODE, TRUE, FALSE, TRUE, "DMU dnode" },
{DMU_BSWAP_OBJSET, TRUE, TRUE, FALSE, "DMU objset" },
{DMU_BSWAP_UINT64, TRUE, TRUE, FALSE, "DSL directory" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL directory child map"},
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL dataset snap map" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL props" },
{DMU_BSWAP_UINT64, TRUE, TRUE, FALSE, "DSL dataset" },
{DMU_BSWAP_ZNODE, TRUE, FALSE, FALSE, "ZFS znode" },
{DMU_BSWAP_OLDACL, TRUE, FALSE, TRUE, "ZFS V0 ACL" },
{DMU_BSWAP_UINT8, FALSE, FALSE, TRUE, "ZFS plain file" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "ZFS directory" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "ZFS master node" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "ZFS delete queue" },
{DMU_BSWAP_UINT8, FALSE, FALSE, TRUE, "zvol object" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "zvol prop" },
{DMU_BSWAP_UINT8, FALSE, FALSE, TRUE, "other uint8[]" },
{DMU_BSWAP_UINT64, FALSE, FALSE, TRUE, "other uint64[]" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "other ZAP" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "persistent error log" },
{DMU_BSWAP_UINT8, TRUE, FALSE, FALSE, "SPA history" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "SPA history offsets" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "Pool properties" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL permissions" },
{DMU_BSWAP_ACL, TRUE, FALSE, TRUE, "ZFS ACL" },
{DMU_BSWAP_UINT8, TRUE, FALSE, TRUE, "ZFS SYSACL" },
{DMU_BSWAP_UINT8, TRUE, FALSE, TRUE, "FUID table" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "FUID table size" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL dataset next clones"},
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "scan work queue" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "ZFS user/group/project used" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "ZFS user/group/project quota"},
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "snapshot refcount tags"},
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "DDT ZAP algorithm" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "DDT statistics" },
{DMU_BSWAP_UINT8, TRUE, FALSE, TRUE, "System attributes" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "SA master node" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "SA attr registration" },
{DMU_BSWAP_ZAP, TRUE, FALSE, TRUE, "SA attr layouts" },
{DMU_BSWAP_ZAP, TRUE, FALSE, FALSE, "scan translations" },
{DMU_BSWAP_UINT8, FALSE, FALSE, TRUE, "deduplicated block" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL deadlist map" },
{DMU_BSWAP_UINT64, TRUE, TRUE, FALSE, "DSL deadlist map hdr" },
{DMU_BSWAP_ZAP, TRUE, TRUE, FALSE, "DSL dir clones" },
{DMU_BSWAP_UINT64, TRUE, FALSE, FALSE, "bpobj subobj" }
};
const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS] = {
{ byteswap_uint8_array, "uint8" },
{ byteswap_uint16_array, "uint16" },
{ byteswap_uint32_array, "uint32" },
{ byteswap_uint64_array, "uint64" },
{ zap_byteswap, "zap" },
{ dnode_buf_byteswap, "dnode" },
{ dmu_objset_byteswap, "objset" },
{ zfs_znode_byteswap, "znode" },
{ zfs_oldacl_byteswap, "oldacl" },
{ zfs_acl_byteswap, "acl" }
};
int
dmu_buf_hold_noread_by_dnode(dnode_t *dn, uint64_t offset,
void *tag, dmu_buf_t **dbp)
{
uint64_t blkid;
dmu_buf_impl_t *db;
blkid = dbuf_whichblock(dn, 0, offset);
rw_enter(&dn->dn_struct_rwlock, RW_READER);
db = dbuf_hold(dn, blkid, tag);
rw_exit(&dn->dn_struct_rwlock);
if (db == NULL) {
*dbp = NULL;
return (SET_ERROR(EIO));
}
*dbp = &db->db;
return (0);
}
int
dmu_buf_hold_noread(objset_t *os, uint64_t object, uint64_t offset,
void *tag, dmu_buf_t **dbp)
{
dnode_t *dn;
uint64_t blkid;
dmu_buf_impl_t *db;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
blkid = dbuf_whichblock(dn, 0, offset);
rw_enter(&dn->dn_struct_rwlock, RW_READER);
db = dbuf_hold(dn, blkid, tag);
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
if (db == NULL) {
*dbp = NULL;
return (SET_ERROR(EIO));
}
*dbp = &db->db;
return (err);
}
int
dmu_buf_hold_by_dnode(dnode_t *dn, uint64_t offset,
void *tag, dmu_buf_t **dbp, int flags)
{
int err;
int db_flags = DB_RF_CANFAIL;
if (flags & DMU_READ_NO_PREFETCH)
db_flags |= DB_RF_NOPREFETCH;
if (flags & DMU_READ_NO_DECRYPT)
db_flags |= DB_RF_NO_DECRYPT;
err = dmu_buf_hold_noread_by_dnode(dn, offset, tag, dbp);
if (err == 0) {
dmu_buf_impl_t *db = (dmu_buf_impl_t *)(*dbp);
err = dbuf_read(db, NULL, db_flags);
if (err != 0) {
dbuf_rele(db, tag);
*dbp = NULL;
}
}
return (err);
}
int
dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
void *tag, dmu_buf_t **dbp, int flags)
{
int err;
int db_flags = DB_RF_CANFAIL;
if (flags & DMU_READ_NO_PREFETCH)
db_flags |= DB_RF_NOPREFETCH;
if (flags & DMU_READ_NO_DECRYPT)
db_flags |= DB_RF_NO_DECRYPT;
err = dmu_buf_hold_noread(os, object, offset, tag, dbp);
if (err == 0) {
dmu_buf_impl_t *db = (dmu_buf_impl_t *)(*dbp);
err = dbuf_read(db, NULL, db_flags);
if (err != 0) {
dbuf_rele(db, tag);
*dbp = NULL;
}
}
return (err);
}
int
dmu_bonus_max(void)
{
return (DN_OLD_MAX_BONUSLEN);
}
int
dmu_set_bonus(dmu_buf_t *db_fake, int newsize, dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
int error;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if (dn->dn_bonus != db) {
error = SET_ERROR(EINVAL);
} else if (newsize < 0 || newsize > db_fake->db_size) {
error = SET_ERROR(EINVAL);
} else {
dnode_setbonuslen(dn, newsize, tx);
error = 0;
}
DB_DNODE_EXIT(db);
return (error);
}
int
dmu_set_bonustype(dmu_buf_t *db_fake, dmu_object_type_t type, dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
int error;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if (!DMU_OT_IS_VALID(type)) {
error = SET_ERROR(EINVAL);
} else if (dn->dn_bonus != db) {
error = SET_ERROR(EINVAL);
} else {
dnode_setbonus_type(dn, type, tx);
error = 0;
}
DB_DNODE_EXIT(db);
return (error);
}
dmu_object_type_t
dmu_get_bonustype(dmu_buf_t *db_fake)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
dmu_object_type_t type;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
type = dn->dn_bonustype;
DB_DNODE_EXIT(db);
return (type);
}
int
dmu_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
{
dnode_t *dn;
int error;
error = dnode_hold(os, object, FTAG, &dn);
dbuf_rm_spill(dn, tx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
dnode_rm_spill(dn, tx);
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
return (error);
}
/*
* Lookup and hold the bonus buffer for the provided dnode. If the dnode
* has not yet been allocated a new bonus dbuf a will be allocated.
* Returns ENOENT, EIO, or 0.
*/
int dmu_bonus_hold_by_dnode(dnode_t *dn, void *tag, dmu_buf_t **dbp,
uint32_t flags)
{
dmu_buf_impl_t *db;
int error;
uint32_t db_flags = DB_RF_MUST_SUCCEED;
if (flags & DMU_READ_NO_PREFETCH)
db_flags |= DB_RF_NOPREFETCH;
if (flags & DMU_READ_NO_DECRYPT)
db_flags |= DB_RF_NO_DECRYPT;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (dn->dn_bonus == NULL) {
rw_exit(&dn->dn_struct_rwlock);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
if (dn->dn_bonus == NULL)
dbuf_create_bonus(dn);
}
db = dn->dn_bonus;
/* as long as the bonus buf is held, the dnode will be held */
if (zfs_refcount_add(&db->db_holds, tag) == 1) {
VERIFY(dnode_add_ref(dn, db));
atomic_inc_32(&dn->dn_dbufs_count);
}
/*
* Wait to drop dn_struct_rwlock until after adding the bonus dbuf's
* hold and incrementing the dbuf count to ensure that dnode_move() sees
* a dnode hold for every dbuf.
*/
rw_exit(&dn->dn_struct_rwlock);
error = dbuf_read(db, NULL, db_flags);
if (error) {
dnode_evict_bonus(dn);
dbuf_rele(db, tag);
*dbp = NULL;
return (error);
}
*dbp = &db->db;
return (0);
}
int
dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
{
dnode_t *dn;
int error;
error = dnode_hold(os, object, FTAG, &dn);
if (error)
return (error);
error = dmu_bonus_hold_by_dnode(dn, tag, dbp, DMU_READ_NO_PREFETCH);
dnode_rele(dn, FTAG);
return (error);
}
/*
* returns ENOENT, EIO, or 0.
*
* This interface will allocate a blank spill dbuf when a spill blk
* doesn't already exist on the dnode.
*
* if you only want to find an already existing spill db, then
* dmu_spill_hold_existing() should be used.
*/
int
dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags, void *tag, dmu_buf_t **dbp)
{
dmu_buf_impl_t *db = NULL;
int err;
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_enter(&dn->dn_struct_rwlock, RW_READER);
db = dbuf_hold(dn, DMU_SPILL_BLKID, tag);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
if (db == NULL) {
*dbp = NULL;
return (SET_ERROR(EIO));
}
err = dbuf_read(db, NULL, flags);
if (err == 0)
*dbp = &db->db;
else {
dbuf_rele(db, tag);
*dbp = NULL;
}
return (err);
}
int
dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
dnode_t *dn;
int err;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_SA) {
err = SET_ERROR(EINVAL);
} else {
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (!dn->dn_have_spill) {
err = SET_ERROR(ENOENT);
} else {
err = dmu_spill_hold_by_dnode(dn,
DB_RF_HAVESTRUCT | DB_RF_CANFAIL, tag, dbp);
}
rw_exit(&dn->dn_struct_rwlock);
}
DB_DNODE_EXIT(db);
return (err);
}
int
dmu_spill_hold_by_bonus(dmu_buf_t *bonus, uint32_t flags, void *tag,
dmu_buf_t **dbp)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
dnode_t *dn;
int err;
uint32_t db_flags = DB_RF_CANFAIL;
if (flags & DMU_READ_NO_DECRYPT)
db_flags |= DB_RF_NO_DECRYPT;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
err = dmu_spill_hold_by_dnode(dn, db_flags, tag, dbp);
DB_DNODE_EXIT(db);
return (err);
}
/*
* Note: longer-term, we should modify all of the dmu_buf_*() interfaces
* to take a held dnode rather than <os, object> -- the lookup is wasteful,
* and can induce severe lock contention when writing to several files
* whose dnodes are in the same block.
*/
static int
dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
boolean_t read, void *tag, int *numbufsp, dmu_buf_t ***dbpp, uint32_t flags)
{
dmu_buf_t **dbp;
uint64_t blkid, nblks, i;
uint32_t dbuf_flags;
int err;
zio_t *zio;
ASSERT(length <= DMU_MAX_ACCESS);
/*
* Note: We directly notify the prefetch code of this read, so that
* we can tell it about the multi-block read. dbuf_read() only knows
* about the one block it is accessing.
*/
dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT |
DB_RF_NOPREFETCH;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (dn->dn_datablkshift) {
int blkshift = dn->dn_datablkshift;
nblks = (P2ROUNDUP(offset + length, 1ULL << blkshift) -
P2ALIGN(offset, 1ULL << blkshift)) >> blkshift;
} else {
if (offset + length > dn->dn_datablksz) {
zfs_panic_recover("zfs: accessing past end of object "
"%llx/%llx (size=%u access=%llu+%llu)",
(longlong_t)dn->dn_objset->
os_dsl_dataset->ds_object,
(longlong_t)dn->dn_object, dn->dn_datablksz,
(longlong_t)offset, (longlong_t)length);
rw_exit(&dn->dn_struct_rwlock);
return (SET_ERROR(EIO));
}
nblks = 1;
}
dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
blkid = dbuf_whichblock(dn, 0, offset);
for (i = 0; i < nblks; i++) {
dmu_buf_impl_t *db = dbuf_hold(dn, blkid + i, tag);
if (db == NULL) {
rw_exit(&dn->dn_struct_rwlock);
dmu_buf_rele_array(dbp, nblks, tag);
zio_nowait(zio);
return (SET_ERROR(EIO));
}
/* initiate async i/o */
if (read)
(void) dbuf_read(db, zio, dbuf_flags);
dbp[i] = &db->db;
}
if ((flags & DMU_READ_NO_PREFETCH) == 0 &&
DNODE_META_IS_CACHEABLE(dn) && length <= zfetch_array_rd_sz) {
dmu_zfetch(&dn->dn_zfetch, blkid, nblks,
read && DNODE_IS_CACHEABLE(dn));
}
rw_exit(&dn->dn_struct_rwlock);
/* wait for async i/o */
err = zio_wait(zio);
if (err) {
dmu_buf_rele_array(dbp, nblks, tag);
return (err);
}
/* wait for other io to complete */
if (read) {
for (i = 0; i < nblks; i++) {
dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
mutex_enter(&db->db_mtx);
while (db->db_state == DB_READ ||
db->db_state == DB_FILL)
cv_wait(&db->db_changed, &db->db_mtx);
if (db->db_state == DB_UNCACHED)
err = SET_ERROR(EIO);
mutex_exit(&db->db_mtx);
if (err) {
dmu_buf_rele_array(dbp, nblks, tag);
return (err);
}
}
}
*numbufsp = nblks;
*dbpp = dbp;
return (0);
}
static int
dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
numbufsp, dbpp, DMU_READ_PREFETCH);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
uint64_t length, boolean_t read, void *tag, int *numbufsp,
dmu_buf_t ***dbpp)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
int err;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
numbufsp, dbpp, DMU_READ_PREFETCH);
DB_DNODE_EXIT(db);
return (err);
}
void
dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
{
int i;
dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
if (numbufs == 0)
return;
for (i = 0; i < numbufs; i++) {
if (dbp[i])
dbuf_rele(dbp[i], tag);
}
kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
}
/*
* Issue prefetch i/os for the given blocks. If level is greater than 0, the
* indirect blocks prefeteched will be those that point to the blocks containing
* the data starting at offset, and continuing to offset + len.
*
* Note that if the indirect blocks above the blocks being prefetched are not
* in cache, they will be asychronously read in.
*/
void
dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
uint64_t len, zio_priority_t pri)
{
dnode_t *dn;
uint64_t blkid;
int nblks, err;
if (len == 0) { /* they're interested in the bonus buffer */
dn = DMU_META_DNODE(os);
if (object == 0 || object >= DN_MAX_OBJECT)
return;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
blkid = dbuf_whichblock(dn, level,
object * sizeof (dnode_phys_t));
dbuf_prefetch(dn, level, blkid, pri, 0);
rw_exit(&dn->dn_struct_rwlock);
return;
}
/*
* See comment before the definition of dmu_prefetch_max.
*/
len = MIN(len, dmu_prefetch_max);
/*
* XXX - Note, if the dnode for the requested object is not
* already cached, we will do a *synchronous* read in the
* dnode_hold() call. The same is true for any indirects.
*/
err = dnode_hold(os, object, FTAG, &dn);
if (err != 0)
return;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
/*
* offset + len - 1 is the last byte we want to prefetch for, and offset
* is the first. Then dbuf_whichblk(dn, level, off + len - 1) is the
* last block we want to prefetch, and dbuf_whichblock(dn, level,
* offset) is the first. Then the number we need to prefetch is the
* last - first + 1.
*/
if (level > 0 || dn->dn_datablkshift != 0) {
nblks = dbuf_whichblock(dn, level, offset + len - 1) -
dbuf_whichblock(dn, level, offset) + 1;
} else {
nblks = (offset < dn->dn_datablksz);
}
if (nblks != 0) {
blkid = dbuf_whichblock(dn, level, offset);
for (int i = 0; i < nblks; i++)
dbuf_prefetch(dn, level, blkid + i, pri, 0);
}
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
}
/*
* Get the next "chunk" of file data to free. We traverse the file from
* the end so that the file gets shorter over time (if we crashes in the
* middle, this will leave us in a better state). We find allocated file
* data by simply searching the allocated level 1 indirects.
*
* On input, *start should be the first offset that does not need to be
* freed (e.g. "offset + length"). On return, *start will be the first
* offset that should be freed and l1blks is set to the number of level 1
* indirect blocks found within the chunk.
*/
static int
get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum, uint64_t *l1blks)
{
uint64_t blks;
uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
/* bytes of data covered by a level-1 indirect block */
uint64_t iblkrange = (uint64_t)dn->dn_datablksz *
EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
ASSERT3U(minimum, <=, *start);
/*
* Check if we can free the entire range assuming that all of the
* L1 blocks in this range have data. If we can, we use this
* worst case value as an estimate so we can avoid having to look
* at the object's actual data.
*/
uint64_t total_l1blks =
(roundup(*start, iblkrange) - (minimum / iblkrange * iblkrange)) /
iblkrange;
if (total_l1blks <= maxblks) {
*l1blks = total_l1blks;
*start = minimum;
return (0);
}
ASSERT(ISP2(iblkrange));
for (blks = 0; *start > minimum && blks < maxblks; blks++) {
int err;
/*
* dnode_next_offset(BACKWARDS) will find an allocated L1
* indirect block at or before the input offset. We must
* decrement *start so that it is at the end of the region
* to search.
*/
(*start)--;
err = dnode_next_offset(dn,
DNODE_FIND_BACKWARDS, start, 2, 1, 0);
/* if there are no indirect blocks before start, we are done */
if (err == ESRCH) {
*start = minimum;
break;
} else if (err != 0) {
*l1blks = blks;
return (err);
}
/* set start to the beginning of this L1 indirect */
*start = P2ALIGN(*start, iblkrange);
}
if (*start < minimum)
*start = minimum;
*l1blks = blks;
return (0);
}
/*
* If this objset is of type OST_ZFS return true if vfs's unmounted flag is set,
* otherwise return false.
* Used below in dmu_free_long_range_impl() to enable abort when unmounting
*/
/*ARGSUSED*/
static boolean_t
dmu_objset_zfs_unmounting(objset_t *os)
{
#ifdef _KERNEL
if (dmu_objset_type(os) == DMU_OST_ZFS)
return (zfs_get_vfs_flag_unmounted(os));
#endif
return (B_FALSE);
}
static int
dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
uint64_t length)
{
uint64_t object_size;
int err;
uint64_t dirty_frees_threshold;
dsl_pool_t *dp = dmu_objset_pool(os);
if (dn == NULL)
return (SET_ERROR(EINVAL));
object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
if (offset >= object_size)
return (0);
if (zfs_per_txg_dirty_frees_percent <= 100)
dirty_frees_threshold =
zfs_per_txg_dirty_frees_percent * zfs_dirty_data_max / 100;
else
dirty_frees_threshold = zfs_dirty_data_max / 20;
if (length == DMU_OBJECT_END || offset + length > object_size)
length = object_size - offset;
while (length != 0) {
uint64_t chunk_end, chunk_begin, chunk_len;
uint64_t l1blks;
dmu_tx_t *tx;
if (dmu_objset_zfs_unmounting(dn->dn_objset))
return (SET_ERROR(EINTR));
chunk_end = chunk_begin = offset + length;
/* move chunk_begin backwards to the beginning of this chunk */
err = get_next_chunk(dn, &chunk_begin, offset, &l1blks);
if (err)
return (err);
ASSERT3U(chunk_begin, >=, offset);
ASSERT3U(chunk_begin, <=, chunk_end);
chunk_len = chunk_end - chunk_begin;
tx = dmu_tx_create(os);
dmu_tx_hold_free(tx, dn->dn_object, chunk_begin, chunk_len);
/*
* Mark this transaction as typically resulting in a net
* reduction in space used.
*/
dmu_tx_mark_netfree(tx);
err = dmu_tx_assign(tx, TXG_WAIT);
if (err) {
dmu_tx_abort(tx);
return (err);
}
uint64_t txg = dmu_tx_get_txg(tx);
mutex_enter(&dp->dp_lock);
uint64_t long_free_dirty =
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK];
mutex_exit(&dp->dp_lock);
/*
* To avoid filling up a TXG with just frees, wait for
* the next TXG to open before freeing more chunks if
* we have reached the threshold of frees.
*/
if (dirty_frees_threshold != 0 &&
long_free_dirty >= dirty_frees_threshold) {
DMU_TX_STAT_BUMP(dmu_tx_dirty_frees_delay);
dmu_tx_commit(tx);
txg_wait_open(dp, 0, B_TRUE);
continue;
}
/*
* In order to prevent unnecessary write throttling, for each
* TXG, we track the cumulative size of L1 blocks being dirtied
* in dnode_free_range() below. We compare this number to a
* tunable threshold, past which we prevent new L1 dirty freeing
* blocks from being added into the open TXG. See
* dmu_free_long_range_impl() for details. The threshold
* prevents write throttle activation due to dirty freeing L1
* blocks taking up a large percentage of zfs_dirty_data_max.
*/
mutex_enter(&dp->dp_lock);
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] +=
l1blks << dn->dn_indblkshift;
mutex_exit(&dp->dp_lock);
DTRACE_PROBE3(free__long__range,
uint64_t, long_free_dirty, uint64_t, chunk_len,
uint64_t, txg);
dnode_free_range(dn, chunk_begin, chunk_len, tx);
dmu_tx_commit(tx);
length -= chunk_len;
}
return (0);
}
int
dmu_free_long_range(objset_t *os, uint64_t object,
uint64_t offset, uint64_t length)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err != 0)
return (err);
err = dmu_free_long_range_impl(os, dn, offset, length);
/*
* It is important to zero out the maxblkid when freeing the entire
* file, so that (a) subsequent calls to dmu_free_long_range_impl()
* will take the fast path, and (b) dnode_reallocate() can verify
* that the entire file has been freed.
*/
if (err == 0 && offset == 0 && length == DMU_OBJECT_END)
dn->dn_maxblkid = 0;
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_free_long_object(objset_t *os, uint64_t object)
{
dmu_tx_t *tx;
int err;
err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END);
if (err != 0)
return (err);
tx = dmu_tx_create(os);
dmu_tx_hold_bonus(tx, object);
dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
dmu_tx_mark_netfree(tx);
err = dmu_tx_assign(tx, TXG_WAIT);
if (err == 0) {
if (err == 0)
err = dmu_object_free(os, object, tx);
dmu_tx_commit(tx);
} else {
dmu_tx_abort(tx);
}
return (err);
}
int
dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
uint64_t size, dmu_tx_t *tx)
{
dnode_t *dn;
int err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
ASSERT(offset < UINT64_MAX);
ASSERT(size == DMU_OBJECT_END || size <= UINT64_MAX - offset);
dnode_free_range(dn, offset, size, tx);
dnode_rele(dn, FTAG);
return (0);
}
static int
dmu_read_impl(dnode_t *dn, uint64_t offset, uint64_t size,
void *buf, uint32_t flags)
{
dmu_buf_t **dbp;
int numbufs, err = 0;
/*
* Deal with odd block sizes, where there can't be data past the first
* block. If we ever do the tail block optimization, we will need to
* handle that here as well.
*/
if (dn->dn_maxblkid == 0) {
uint64_t newsz = offset > dn->dn_datablksz ? 0 :
MIN(size, dn->dn_datablksz - offset);
bzero((char *)buf + newsz, size - newsz);
size = newsz;
}
while (size > 0) {
uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
int i;
/*
* NB: we could do this block-at-a-time, but it's nice
* to be reading in parallel.
*/
err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
TRUE, FTAG, &numbufs, &dbp, flags);
if (err)
break;
for (i = 0; i < numbufs; i++) {
uint64_t tocpy;
int64_t bufoff;
dmu_buf_t *db = dbp[i];
ASSERT(size > 0);
bufoff = offset - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
(void) memcpy(buf, (char *)db->db_data + bufoff, tocpy);
offset += tocpy;
size -= tocpy;
buf = (char *)buf + tocpy;
}
dmu_buf_rele_array(dbp, numbufs, FTAG);
}
return (err);
}
int
dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
void *buf, uint32_t flags)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err != 0)
return (err);
err = dmu_read_impl(dn, offset, size, buf, flags);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_read_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size, void *buf,
uint32_t flags)
{
return (dmu_read_impl(dn, offset, size, buf, flags));
}
static void
dmu_write_impl(dmu_buf_t **dbp, int numbufs, uint64_t offset, uint64_t size,
const void *buf, dmu_tx_t *tx)
{
int i;
for (i = 0; i < numbufs; i++) {
uint64_t tocpy;
int64_t bufoff;
dmu_buf_t *db = dbp[i];
ASSERT(size > 0);
bufoff = offset - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
if (tocpy == db->db_size)
dmu_buf_will_fill(db, tx);
else
dmu_buf_will_dirty(db, tx);
(void) memcpy((char *)db->db_data + bufoff, buf, tocpy);
if (tocpy == db->db_size)
dmu_buf_fill_done(db, tx);
offset += tocpy;
size -= tocpy;
buf = (char *)buf + tocpy;
}
}
void
dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
const void *buf, dmu_tx_t *tx)
{
dmu_buf_t **dbp;
int numbufs;
if (size == 0)
return;
VERIFY0(dmu_buf_hold_array(os, object, offset, size,
FALSE, FTAG, &numbufs, &dbp));
dmu_write_impl(dbp, numbufs, offset, size, buf, tx);
dmu_buf_rele_array(dbp, numbufs, FTAG);
}
/*
* Note: Lustre is an external consumer of this interface.
*/
void
dmu_write_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size,
const void *buf, dmu_tx_t *tx)
{
dmu_buf_t **dbp;
int numbufs;
if (size == 0)
return;
VERIFY0(dmu_buf_hold_array_by_dnode(dn, offset, size,
FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH));
dmu_write_impl(dbp, numbufs, offset, size, buf, tx);
dmu_buf_rele_array(dbp, numbufs, FTAG);
}
static int
dmu_object_remap_one_indirect(objset_t *os, dnode_t *dn,
uint64_t last_removal_txg, uint64_t offset)
{
uint64_t l1blkid = dbuf_whichblock(dn, 1, offset);
dnode_t *dn_tx;
int err = 0;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
dmu_buf_impl_t *dbuf = dbuf_hold_level(dn, 1, l1blkid, FTAG);
ASSERT3P(dbuf, !=, NULL);
/*
* If the block hasn't been written yet, this default will ensure
* we don't try to remap it.
*/
uint64_t birth = UINT64_MAX;
ASSERT3U(last_removal_txg, !=, UINT64_MAX);
if (dbuf->db_blkptr != NULL)
birth = dbuf->db_blkptr->blk_birth;
rw_exit(&dn->dn_struct_rwlock);
/*
* If this L1 was already written after the last removal, then we've
* already tried to remap it. An additional hold is taken after the
* dmu_tx_assign() to handle the case where the dnode is freed while
* waiting for the next open txg.
*/
if (birth <= last_removal_txg &&
dbuf_read(dbuf, NULL, DB_RF_MUST_SUCCEED) == 0 &&
dbuf_can_remap(dbuf)) {
dmu_tx_t *tx = dmu_tx_create(os);
dmu_tx_hold_remap_l1indirect(tx, dn->dn_object);
err = dmu_tx_assign(tx, TXG_WAIT);
if (err == 0) {
err = dnode_hold(os, dn->dn_object, FTAG, &dn_tx);
if (err == 0) {
(void) dbuf_dirty(dbuf, tx);
dnode_rele(dn_tx, FTAG);
}
dmu_tx_commit(tx);
} else {
dmu_tx_abort(tx);
}
}
dbuf_rele(dbuf, FTAG);
delay(MSEC_TO_TICK(zfs_object_remap_one_indirect_delay_ms));
return (err);
}
/*
* Remap all blockpointers in the object, if possible, so that they reference
* only concrete vdevs.
*
* To do this, iterate over the L0 blockpointers and remap any that reference
* an indirect vdev. Note that we only examine L0 blockpointers; since we
* cannot guarantee that we can remap all blockpointer anyways (due to split
* blocks), we do not want to make the code unnecessarily complicated to
* catch the unlikely case that there is an L1 block on an indirect vdev that
* contains no indirect blockpointers.
*/
int
dmu_object_remap_indirects(objset_t *os, uint64_t object,
uint64_t last_removal_txg)
{
uint64_t offset, l1span;
int err;
dnode_t *dn, *dn_tx;
err = dnode_hold(os, object, FTAG, &dn);
if (err != 0) {
return (err);
}
if (dn->dn_nlevels <= 1) {
if (issig(JUSTLOOKING) && issig(FORREAL)) {
err = SET_ERROR(EINTR);
}
/*
* If the dnode has no indirect blocks, we cannot dirty them.
* We still want to remap the blkptr(s) in the dnode if
* appropriate, so mark it as dirty. An additional hold is
* taken after the dmu_tx_assign() to handle the case where
* the dnode is freed while waiting for the next open txg.
*/
if (err == 0 && dnode_needs_remap(dn)) {
dmu_tx_t *tx = dmu_tx_create(os);
dmu_tx_hold_bonus(tx, object);
err = dmu_tx_assign(tx, TXG_WAIT);
if (err == 0) {
err = dnode_hold(os, object, FTAG, &dn_tx);
if (err == 0) {
dnode_setdirty(dn_tx, tx);
dnode_rele(dn_tx, FTAG);
}
dmu_tx_commit(tx);
} else {
dmu_tx_abort(tx);
}
}
dnode_rele(dn, FTAG);
return (err);
}
offset = 0;
l1span = 1ULL << (dn->dn_indblkshift - SPA_BLKPTRSHIFT +
dn->dn_datablkshift);
/*
* Find the next L1 indirect that is not a hole.
*/
while (dnode_next_offset(dn, 0, &offset, 2, 1, 0) == 0) {
if (issig(JUSTLOOKING) && issig(FORREAL)) {
err = SET_ERROR(EINTR);
break;
}
if ((err = dmu_object_remap_one_indirect(os, dn,
last_removal_txg, offset)) != 0) {
break;
}
offset += l1span;
}
dnode_rele(dn, FTAG);
return (err);
}
void
dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
dmu_tx_t *tx)
{
dmu_buf_t **dbp;
int numbufs, i;
if (size == 0)
return;
VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
FALSE, FTAG, &numbufs, &dbp));
for (i = 0; i < numbufs; i++) {
dmu_buf_t *db = dbp[i];
dmu_buf_will_not_fill(db, tx);
}
dmu_buf_rele_array(dbp, numbufs, FTAG);
}
void
dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
int compressed_size, int byteorder, dmu_tx_t *tx)
{
dmu_buf_t *db;
ASSERT3U(etype, <, NUM_BP_EMBEDDED_TYPES);
ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS);
VERIFY0(dmu_buf_hold_noread(os, object, offset,
FTAG, &db));
dmu_buf_write_embedded(db,
data, (bp_embedded_type_t)etype, (enum zio_compress)comp,
uncompressed_size, compressed_size, byteorder, tx);
dmu_buf_rele(db, FTAG);
}
/*
* DMU support for xuio
*/
kstat_t *xuio_ksp = NULL;
typedef struct xuio_stats {
/* loaned yet not returned arc_buf */
kstat_named_t xuiostat_onloan_rbuf;
kstat_named_t xuiostat_onloan_wbuf;
/* whether a copy is made when loaning out a read buffer */
kstat_named_t xuiostat_rbuf_copied;
kstat_named_t xuiostat_rbuf_nocopy;
/* whether a copy is made when assigning a write buffer */
kstat_named_t xuiostat_wbuf_copied;
kstat_named_t xuiostat_wbuf_nocopy;
} xuio_stats_t;
static xuio_stats_t xuio_stats = {
{ "onloan_read_buf", KSTAT_DATA_UINT64 },
{ "onloan_write_buf", KSTAT_DATA_UINT64 },
{ "read_buf_copied", KSTAT_DATA_UINT64 },
{ "read_buf_nocopy", KSTAT_DATA_UINT64 },
{ "write_buf_copied", KSTAT_DATA_UINT64 },
{ "write_buf_nocopy", KSTAT_DATA_UINT64 }
};
#define XUIOSTAT_INCR(stat, val) \
atomic_add_64(&xuio_stats.stat.value.ui64, (val))
#define XUIOSTAT_BUMP(stat) XUIOSTAT_INCR(stat, 1)
#ifdef HAVE_UIO_ZEROCOPY
int
dmu_xuio_init(xuio_t *xuio, int nblk)
{
dmu_xuio_t *priv;
uio_t *uio = &xuio->xu_uio;
uio->uio_iovcnt = nblk;
uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
priv->cnt = nblk;
priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
priv->iovp = (iovec_t *)uio->uio_iov;
XUIO_XUZC_PRIV(xuio) = priv;
if (XUIO_XUZC_RW(xuio) == UIO_READ)
XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
else
XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
return (0);
}
void
dmu_xuio_fini(xuio_t *xuio)
{
dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
int nblk = priv->cnt;
kmem_free(priv->iovp, nblk * sizeof (iovec_t));
kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
kmem_free(priv, sizeof (dmu_xuio_t));
if (XUIO_XUZC_RW(xuio) == UIO_READ)
XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
else
XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
}
/*
* Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
* and increase priv->next by 1.
*/
int
dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
{
struct iovec *iov;
uio_t *uio = &xuio->xu_uio;
dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
int i = priv->next++;
ASSERT(i < priv->cnt);
ASSERT(off + n <= arc_buf_lsize(abuf));
iov = (iovec_t *)uio->uio_iov + i;
iov->iov_base = (char *)abuf->b_data + off;
iov->iov_len = n;
priv->bufs[i] = abuf;
return (0);
}
int
dmu_xuio_cnt(xuio_t *xuio)
{
dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
return (priv->cnt);
}
arc_buf_t *
dmu_xuio_arcbuf(xuio_t *xuio, int i)
{
dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
ASSERT(i < priv->cnt);
return (priv->bufs[i]);
}
void
dmu_xuio_clear(xuio_t *xuio, int i)
{
dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
ASSERT(i < priv->cnt);
priv->bufs[i] = NULL;
}
#endif /* HAVE_UIO_ZEROCOPY */
static void
xuio_stat_init(void)
{
xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
KSTAT_FLAG_VIRTUAL);
if (xuio_ksp != NULL) {
xuio_ksp->ks_data = &xuio_stats;
kstat_install(xuio_ksp);
}
}
static void
xuio_stat_fini(void)
{
if (xuio_ksp != NULL) {
kstat_delete(xuio_ksp);
xuio_ksp = NULL;
}
}
void
xuio_stat_wbuf_copied(void)
{
XUIOSTAT_BUMP(xuiostat_wbuf_copied);
}
void
xuio_stat_wbuf_nocopy(void)
{
XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
}
#ifdef _KERNEL
int
dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
{
dmu_buf_t **dbp;
int numbufs, i, err;
#ifdef HAVE_UIO_ZEROCOPY
xuio_t *xuio = NULL;
#endif
/*
* NB: we could do this block-at-a-time, but it's nice
* to be reading in parallel.
*/
err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
TRUE, FTAG, &numbufs, &dbp, 0);
if (err)
return (err);
for (i = 0; i < numbufs; i++) {
uint64_t tocpy;
int64_t bufoff;
dmu_buf_t *db = dbp[i];
ASSERT(size > 0);
bufoff = uio->uio_loffset - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
#ifdef HAVE_UIO_ZEROCOPY
if (xuio) {
dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
arc_buf_t *dbuf_abuf = dbi->db_buf;
arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
if (!err) {
uio->uio_resid -= tocpy;
uio->uio_loffset += tocpy;
}
if (abuf == dbuf_abuf)
XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
else
XUIOSTAT_BUMP(xuiostat_rbuf_copied);
} else
#endif
err = uiomove((char *)db->db_data + bufoff, tocpy,
UIO_READ, uio);
if (err)
break;
size -= tocpy;
}
dmu_buf_rele_array(dbp, numbufs, FTAG);
return (err);
}
/*
* Read 'size' bytes into the uio buffer.
* From object zdb->db_object.
* Starting at offset uio->uio_loffset.
*
* If the caller already has a dbuf in the target object
* (e.g. its bonus buffer), this routine is faster than dmu_read_uio(),
* because we don't have to find the dnode_t for the object.
*/
int
dmu_read_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
dnode_t *dn;
int err;
if (size == 0)
return (0);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
err = dmu_read_uio_dnode(dn, uio, size);
DB_DNODE_EXIT(db);
return (err);
}
/*
* Read 'size' bytes into the uio buffer.
* From the specified object
* Starting at offset uio->uio_loffset.
*/
int
dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
{
dnode_t *dn;
int err;
if (size == 0)
return (0);
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
err = dmu_read_uio_dnode(dn, uio, size);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
{
dmu_buf_t **dbp;
int numbufs;
int err = 0;
int i;
err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
if (err)
return (err);
for (i = 0; i < numbufs; i++) {
uint64_t tocpy;
int64_t bufoff;
dmu_buf_t *db = dbp[i];
ASSERT(size > 0);
bufoff = uio->uio_loffset - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
if (tocpy == db->db_size)
dmu_buf_will_fill(db, tx);
else
dmu_buf_will_dirty(db, tx);
/*
* XXX uiomove could block forever (eg.nfs-backed
* pages). There needs to be a uiolockdown() function
* to lock the pages in memory, so that uiomove won't
* block.
*/
err = uiomove((char *)db->db_data + bufoff, tocpy,
UIO_WRITE, uio);
if (tocpy == db->db_size)
dmu_buf_fill_done(db, tx);
if (err)
break;
size -= tocpy;
}
dmu_buf_rele_array(dbp, numbufs, FTAG);
return (err);
}
/*
* Write 'size' bytes from the uio buffer.
* To object zdb->db_object.
* Starting at offset uio->uio_loffset.
*
* If the caller already has a dbuf in the target object
* (e.g. its bonus buffer), this routine is faster than dmu_write_uio(),
* because we don't have to find the dnode_t for the object.
*/
int
dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
dnode_t *dn;
int err;
if (size == 0)
return (0);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
err = dmu_write_uio_dnode(dn, uio, size, tx);
DB_DNODE_EXIT(db);
return (err);
}
/*
* Write 'size' bytes from the uio buffer.
* To the specified object.
* Starting at offset uio->uio_loffset.
*/
int
dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
dmu_tx_t *tx)
{
dnode_t *dn;
int err;
if (size == 0)
return (0);
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
err = dmu_write_uio_dnode(dn, uio, size, tx);
dnode_rele(dn, FTAG);
return (err);
}
#endif /* _KERNEL */
/*
* Allocate a loaned anonymous arc buffer.
*/
arc_buf_t *
dmu_request_arcbuf(dmu_buf_t *handle, int size)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
return (arc_loan_buf(db->db_objset->os_spa, B_FALSE, size));
}
/*
* Free a loaned arc buffer.
*/
void
dmu_return_arcbuf(arc_buf_t *buf)
{
arc_return_buf(buf, FTAG);
arc_buf_destroy(buf, FTAG);
}
void
dmu_copy_from_buf(objset_t *os, uint64_t object, uint64_t offset,
dmu_buf_t *handle, dmu_tx_t *tx)
{
dmu_buf_t *dst_handle;
dmu_buf_impl_t *dstdb;
dmu_buf_impl_t *srcdb = (dmu_buf_impl_t *)handle;
dmu_object_type_t type;
arc_buf_t *abuf;
uint64_t datalen;
boolean_t byteorder;
uint8_t salt[ZIO_DATA_SALT_LEN];
uint8_t iv[ZIO_DATA_IV_LEN];
uint8_t mac[ZIO_DATA_MAC_LEN];
ASSERT3P(srcdb->db_buf, !=, NULL);
/* hold the db that we want to write to */
VERIFY0(dmu_buf_hold(os, object, offset, FTAG, &dst_handle,
DMU_READ_NO_DECRYPT));
dstdb = (dmu_buf_impl_t *)dst_handle;
datalen = arc_buf_size(srcdb->db_buf);
DB_DNODE_ENTER(dstdb);
type = DB_DNODE(dstdb)->dn_type;
DB_DNODE_EXIT(dstdb);
/* allocated an arc buffer that matches the type of srcdb->db_buf */
if (arc_is_encrypted(srcdb->db_buf)) {
arc_get_raw_params(srcdb->db_buf, &byteorder, salt, iv, mac);
abuf = arc_loan_raw_buf(os->os_spa, dmu_objset_id(os),
byteorder, salt, iv, mac, type,
datalen, arc_buf_lsize(srcdb->db_buf),
arc_get_compression(srcdb->db_buf));
} else {
/* we won't get a compressed db back from dmu_buf_hold() */
ASSERT3U(arc_get_compression(srcdb->db_buf),
==, ZIO_COMPRESS_OFF);
abuf = arc_loan_buf(os->os_spa,
DMU_OT_IS_METADATA(type), datalen);
}
ASSERT3U(datalen, ==, arc_buf_size(abuf));
/* copy the data to the new buffer and assign it to the dstdb */
bcopy(srcdb->db_buf->b_data, abuf->b_data, datalen);
dbuf_assign_arcbuf(dstdb, abuf, tx);
dmu_buf_rele(dst_handle, FTAG);
}
/*
* When possible directly assign passed loaned arc buffer to a dbuf.
* If this is not possible copy the contents of passed arc buf via
* dmu_write().
*/
int
dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset, arc_buf_t *buf,
dmu_tx_t *tx)
{
dmu_buf_impl_t *db;
objset_t *os = dn->dn_objset;
uint64_t object = dn->dn_object;
uint32_t blksz = (uint32_t)arc_buf_lsize(buf);
uint64_t blkid;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
blkid = dbuf_whichblock(dn, 0, offset);
db = dbuf_hold(dn, blkid, FTAG);
if (db == NULL)
return (SET_ERROR(EIO));
rw_exit(&dn->dn_struct_rwlock);
/*
* We can only assign if the offset is aligned, the arc buf is the
* same size as the dbuf, and the dbuf is not metadata.
*/
if (offset == db->db.db_offset && blksz == db->db.db_size) {
dbuf_assign_arcbuf(db, buf, tx);
dbuf_rele(db, FTAG);
} else {
/* compressed bufs must always be assignable to their dbuf */
ASSERT3U(arc_get_compression(buf), ==, ZIO_COMPRESS_OFF);
ASSERT(!(buf->b_flags & ARC_BUF_FLAG_COMPRESSED));
dbuf_rele(db, FTAG);
dmu_write(os, object, offset, blksz, buf->b_data, tx);
dmu_return_arcbuf(buf);
XUIOSTAT_BUMP(xuiostat_wbuf_copied);
}
return (0);
}
int
dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
dmu_tx_t *tx)
{
int err;
dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
DB_DNODE_ENTER(dbuf);
err = dmu_assign_arcbuf_by_dnode(DB_DNODE(dbuf), offset, buf, tx);
DB_DNODE_EXIT(dbuf);
return (err);
}
typedef struct {
dbuf_dirty_record_t *dsa_dr;
dmu_sync_cb_t *dsa_done;
zgd_t *dsa_zgd;
dmu_tx_t *dsa_tx;
} dmu_sync_arg_t;
/* ARGSUSED */
static void
dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
{
dmu_sync_arg_t *dsa = varg;
dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
blkptr_t *bp = zio->io_bp;
if (zio->io_error == 0) {
if (BP_IS_HOLE(bp)) {
/*
* A block of zeros may compress to a hole, but the
* block size still needs to be known for replay.
*/
BP_SET_LSIZE(bp, db->db_size);
} else if (!BP_IS_EMBEDDED(bp)) {
ASSERT(BP_GET_LEVEL(bp) == 0);
BP_SET_FILL(bp, 1);
}
}
}
static void
dmu_sync_late_arrival_ready(zio_t *zio)
{
dmu_sync_ready(zio, NULL, zio->io_private);
}
/* ARGSUSED */
static void
dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
{
dmu_sync_arg_t *dsa = varg;
dbuf_dirty_record_t *dr = dsa->dsa_dr;
dmu_buf_impl_t *db = dr->dr_dbuf;
zgd_t *zgd = dsa->dsa_zgd;
/*
* Record the vdev(s) backing this blkptr so they can be flushed after
* the writes for the lwb have completed.
*/
if (zio->io_error == 0) {
zil_lwb_add_block(zgd->zgd_lwb, zgd->zgd_bp);
}
mutex_enter(&db->db_mtx);
ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
if (zio->io_error == 0) {
dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
if (dr->dt.dl.dr_nopwrite) {
blkptr_t *bp = zio->io_bp;
blkptr_t *bp_orig = &zio->io_bp_orig;
uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
ASSERT(BP_EQUAL(bp, bp_orig));
VERIFY(BP_EQUAL(bp, db->db_blkptr));
ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
VERIFY(zio_checksum_table[chksum].ci_flags &
ZCHECKSUM_FLAG_NOPWRITE);
}
dr->dt.dl.dr_overridden_by = *zio->io_bp;
dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
/*
* Old style holes are filled with all zeros, whereas
* new-style holes maintain their lsize, type, level,
* and birth time (see zio_write_compress). While we
* need to reset the BP_SET_LSIZE() call that happened
* in dmu_sync_ready for old style holes, we do *not*
* want to wipe out the information contained in new
* style holes. Thus, only zero out the block pointer if
* it's an old style hole.
*/
if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by) &&
dr->dt.dl.dr_overridden_by.blk_birth == 0)
BP_ZERO(&dr->dt.dl.dr_overridden_by);
} else {
dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
}
cv_broadcast(&db->db_changed);
mutex_exit(&db->db_mtx);
dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
kmem_free(dsa, sizeof (*dsa));
}
static void
dmu_sync_late_arrival_done(zio_t *zio)
{
blkptr_t *bp = zio->io_bp;
dmu_sync_arg_t *dsa = zio->io_private;
zgd_t *zgd = dsa->dsa_zgd;
if (zio->io_error == 0) {
/*
* Record the vdev(s) backing this blkptr so they can be
* flushed after the writes for the lwb have completed.
*/
zil_lwb_add_block(zgd->zgd_lwb, zgd->zgd_bp);
if (!BP_IS_HOLE(bp)) {
ASSERTV(blkptr_t *bp_orig = &zio->io_bp_orig);
ASSERT(!(zio->io_flags & ZIO_FLAG_NOPWRITE));
ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
ASSERT(zio->io_bp->blk_birth == zio->io_txg);
ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
}
}
dmu_tx_commit(dsa->dsa_tx);
dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
abd_put(zio->io_abd);
kmem_free(dsa, sizeof (*dsa));
}
static int
dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
zio_prop_t *zp, zbookmark_phys_t *zb)
{
dmu_sync_arg_t *dsa;
dmu_tx_t *tx;
tx = dmu_tx_create(os);
dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
dmu_tx_abort(tx);
/* Make zl_get_data do txg_waited_synced() */
return (SET_ERROR(EIO));
}
/*
* In order to prevent the zgd's lwb from being free'd prior to
* dmu_sync_late_arrival_done() being called, we have to ensure
* the lwb's "max txg" takes this tx's txg into account.
*/
zil_lwb_add_txg(zgd->zgd_lwb, dmu_tx_get_txg(tx));
dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
dsa->dsa_dr = NULL;
dsa->dsa_done = done;
dsa->dsa_zgd = zgd;
dsa->dsa_tx = tx;
/*
* Since we are currently syncing this txg, it's nontrivial to
* determine what BP to nopwrite against, so we disable nopwrite.
*
* When syncing, the db_blkptr is initially the BP of the previous
* txg. We can not nopwrite against it because it will be changed
* (this is similar to the non-late-arrival case where the dbuf is
* dirty in a future txg).
*
* Then dbuf_write_ready() sets bp_blkptr to the location we will write.
* We can not nopwrite against it because although the BP will not
* (typically) be changed, the data has not yet been persisted to this
* location.
*
* Finally, when dbuf_write_done() is called, it is theoretically
* possible to always nopwrite, because the data that was written in
* this txg is the same data that we are trying to write. However we
* would need to check that this dbuf is not dirty in any future
* txg's (as we do in the normal dmu_sync() path). For simplicity, we
* don't nopwrite in this case.
*/
zp->zp_nopwrite = B_FALSE;
zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
abd_get_from_buf(zgd->zgd_db->db_data, zgd->zgd_db->db_size),
zgd->zgd_db->db_size, zgd->zgd_db->db_size, zp,
dmu_sync_late_arrival_ready, NULL, NULL, dmu_sync_late_arrival_done,
dsa, ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
return (0);
}
/*
* Intent log support: sync the block associated with db to disk.
* N.B. and XXX: the caller is responsible for making sure that the
* data isn't changing while dmu_sync() is writing it.
*
* Return values:
*
* EEXIST: this txg has already been synced, so there's nothing to do.
* The caller should not log the write.
*
* ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
* The caller should not log the write.
*
* EALREADY: this block is already in the process of being synced.
* The caller should track its progress (somehow).
*
* EIO: could not do the I/O.
* The caller should do a txg_wait_synced().
*
* 0: the I/O has been initiated.
* The caller should log this blkptr in the done callback.
* It is possible that the I/O will fail, in which case
* the error will be reported to the done callback and
* propagated to pio from zio_done().
*/
int
dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
objset_t *os = db->db_objset;
dsl_dataset_t *ds = os->os_dsl_dataset;
dbuf_dirty_record_t *dr;
dmu_sync_arg_t *dsa;
zbookmark_phys_t zb;
zio_prop_t zp;
dnode_t *dn;
ASSERT(pio != NULL);
ASSERT(txg != 0);
SET_BOOKMARK(&zb, ds->ds_object,
db->db.db_object, db->db_level, db->db_blkid);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
DB_DNODE_EXIT(db);
/*
* If we're frozen (running ziltest), we always need to generate a bp.
*/
if (txg > spa_freeze_txg(os->os_spa))
return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
/*
* Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
* and us. If we determine that this txg is not yet syncing,
* but it begins to sync a moment later, that's OK because the
* sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
*/
mutex_enter(&db->db_mtx);
if (txg <= spa_last_synced_txg(os->os_spa)) {
/*
* This txg has already synced. There's nothing to do.
*/
mutex_exit(&db->db_mtx);
return (SET_ERROR(EEXIST));
}
if (txg <= spa_syncing_txg(os->os_spa)) {
/*
* This txg is currently syncing, so we can't mess with
* the dirty record anymore; just write a new log block.
*/
mutex_exit(&db->db_mtx);
return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
}
dr = db->db_last_dirty;
while (dr && dr->dr_txg != txg)
dr = dr->dr_next;
if (dr == NULL) {
/*
* There's no dr for this dbuf, so it must have been freed.
* There's no need to log writes to freed blocks, so we're done.
*/
mutex_exit(&db->db_mtx);
return (SET_ERROR(ENOENT));
}
ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
if (db->db_blkptr != NULL) {
/*
* We need to fill in zgd_bp with the current blkptr so that
* the nopwrite code can check if we're writing the same
* data that's already on disk. We can only nopwrite if we
* are sure that after making the copy, db_blkptr will not
* change until our i/o completes. We ensure this by
* holding the db_mtx, and only allowing nopwrite if the
* block is not already dirty (see below). This is verified
* by dmu_sync_done(), which VERIFYs that the db_blkptr has
* not changed.
*/
*zgd->zgd_bp = *db->db_blkptr;
}
/*
* Assume the on-disk data is X, the current syncing data (in
* txg - 1) is Y, and the current in-memory data is Z (currently
* in dmu_sync).
*
* We usually want to perform a nopwrite if X and Z are the
* same. However, if Y is different (i.e. the BP is going to
* change before this write takes effect), then a nopwrite will
* be incorrect - we would override with X, which could have
* been freed when Y was written.
*
* (Note that this is not a concern when we are nop-writing from
* syncing context, because X and Y must be identical, because
* all previous txgs have been synced.)
*
* Therefore, we disable nopwrite if the current BP could change
* before this TXG. There are two ways it could change: by
* being dirty (dr_next is non-NULL), or by being freed
* (dnode_block_freed()). This behavior is verified by
* zio_done(), which VERIFYs that the override BP is identical
* to the on-disk BP.
*/
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if (dr->dr_next != NULL || dnode_block_freed(dn, db->db_blkid))
zp.zp_nopwrite = B_FALSE;
DB_DNODE_EXIT(db);
ASSERT(dr->dr_txg == txg);
if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
/*
* We have already issued a sync write for this buffer,
* or this buffer has already been synced. It could not
* have been dirtied since, or we would have cleared the state.
*/
mutex_exit(&db->db_mtx);
return (SET_ERROR(EALREADY));
}
ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
mutex_exit(&db->db_mtx);
dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
dsa->dsa_dr = dr;
dsa->dsa_done = done;
dsa->dsa_zgd = zgd;
dsa->dsa_tx = NULL;
zio_nowait(arc_write(pio, os->os_spa, txg,
zgd->zgd_bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db),
&zp, dmu_sync_ready, NULL, NULL, dmu_sync_done, dsa,
ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, &zb));
return (0);
}
int
dmu_object_set_nlevels(objset_t *os, uint64_t object, int nlevels, dmu_tx_t *tx)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
err = dnode_set_nlevels(dn, nlevels, tx);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
dmu_tx_t *tx)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
err = dnode_set_blksz(dn, size, ibs, tx);
dnode_rele(dn, FTAG);
return (err);
}
int
dmu_object_set_maxblkid(objset_t *os, uint64_t object, uint64_t maxblkid,
dmu_tx_t *tx)
{
dnode_t *dn;
int err;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
dnode_new_blkid(dn, maxblkid, tx, B_FALSE, B_TRUE);
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
return (0);
}
void
dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
dmu_tx_t *tx)
{
dnode_t *dn;
/*
* Send streams include each object's checksum function. This
* check ensures that the receiving system can understand the
* checksum function transmitted.
*/
ASSERT3U(checksum, <, ZIO_CHECKSUM_LEGACY_FUNCTIONS);
VERIFY0(dnode_hold(os, object, FTAG, &dn));
ASSERT3U(checksum, <, ZIO_CHECKSUM_FUNCTIONS);
dn->dn_checksum = checksum;
dnode_setdirty(dn, tx);
dnode_rele(dn, FTAG);
}
void
dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
dmu_tx_t *tx)
{
dnode_t *dn;
/*
* Send streams include each object's compression function. This
* check ensures that the receiving system can understand the
* compression function transmitted.
*/
ASSERT3U(compress, <, ZIO_COMPRESS_LEGACY_FUNCTIONS);
VERIFY0(dnode_hold(os, object, FTAG, &dn));
dn->dn_compress = compress;
dnode_setdirty(dn, tx);
dnode_rele(dn, FTAG);
}
/*
* When the "redundant_metadata" property is set to "most", only indirect
* blocks of this level and higher will have an additional ditto block.
*/
int zfs_redundant_metadata_most_ditto_level = 2;
void
dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
{
dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
(wp & WP_SPILL));
enum zio_checksum checksum = os->os_checksum;
enum zio_compress compress = os->os_compress;
enum zio_checksum dedup_checksum = os->os_dedup_checksum;
boolean_t dedup = B_FALSE;
boolean_t nopwrite = B_FALSE;
boolean_t dedup_verify = os->os_dedup_verify;
boolean_t encrypt = B_FALSE;
int copies = os->os_copies;
/*
* We maintain different write policies for each of the following
* types of data:
* 1. metadata
* 2. preallocated blocks (i.e. level-0 blocks of a dump device)
* 3. all other level 0 blocks
*/
if (ismd) {
/*
* XXX -- we should design a compression algorithm
* that specializes in arrays of bps.
*/
compress = zio_compress_select(os->os_spa,
ZIO_COMPRESS_ON, ZIO_COMPRESS_ON);
/*
* Metadata always gets checksummed. If the data
* checksum is multi-bit correctable, and it's not a
* ZBT-style checksum, then it's suitable for metadata
* as well. Otherwise, the metadata checksum defaults
* to fletcher4.
*/
if (!(zio_checksum_table[checksum].ci_flags &
ZCHECKSUM_FLAG_METADATA) ||
(zio_checksum_table[checksum].ci_flags &
ZCHECKSUM_FLAG_EMBEDDED))
checksum = ZIO_CHECKSUM_FLETCHER_4;
if (os->os_redundant_metadata == ZFS_REDUNDANT_METADATA_ALL ||
(os->os_redundant_metadata ==
ZFS_REDUNDANT_METADATA_MOST &&
(level >= zfs_redundant_metadata_most_ditto_level ||
DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))))
copies++;
} else if (wp & WP_NOFILL) {
ASSERT(level == 0);
/*
* If we're writing preallocated blocks, we aren't actually
* writing them so don't set any policy properties. These
* blocks are currently only used by an external subsystem
* outside of zfs (i.e. dump) and not written by the zio
* pipeline.
*/
compress = ZIO_COMPRESS_OFF;
checksum = ZIO_CHECKSUM_OFF;
} else {
compress = zio_compress_select(os->os_spa, dn->dn_compress,
compress);
checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
zio_checksum_select(dn->dn_checksum, checksum) :
dedup_checksum;
/*
* Determine dedup setting. If we are in dmu_sync(),
* we won't actually dedup now because that's all
* done in syncing context; but we do want to use the
* dedup checkum. If the checksum is not strong
* enough to ensure unique signatures, force
* dedup_verify.
*/
if (dedup_checksum != ZIO_CHECKSUM_OFF) {
dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
if (!(zio_checksum_table[checksum].ci_flags &
ZCHECKSUM_FLAG_DEDUP))
dedup_verify = B_TRUE;
}
/*
* Enable nopwrite if we have secure enough checksum
* algorithm (see comment in zio_nop_write) and
* compression is enabled. We don't enable nopwrite if
* dedup is enabled as the two features are mutually
* exclusive.
*/
nopwrite = (!dedup && (zio_checksum_table[checksum].ci_flags &
ZCHECKSUM_FLAG_NOPWRITE) &&
compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
}
/*
* All objects in an encrypted objset are protected from modification
* via a MAC. Encrypted objects store their IV and salt in the last DVA
* in the bp, so we cannot use all copies. Encrypted objects are also
* not subject to nopwrite since writing the same data will still
* result in a new ciphertext. Only encrypted blocks can be dedup'd
* to avoid ambiguity in the dedup code since the DDT does not store
* object types.
*/
if (os->os_encrypted && (wp & WP_NOFILL) == 0) {
encrypt = B_TRUE;
if (DMU_OT_IS_ENCRYPTED(type)) {
copies = MIN(copies, SPA_DVAS_PER_BP - 1);
nopwrite = B_FALSE;
} else {
dedup = B_FALSE;
}
if (level <= 0 &&
(type == DMU_OT_DNODE || type == DMU_OT_OBJSET)) {
compress = ZIO_COMPRESS_EMPTY;
}
}
zp->zp_compress = compress;
zp->zp_checksum = checksum;
zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
zp->zp_level = level;
zp->zp_copies = MIN(copies, spa_max_replication(os->os_spa));
zp->zp_dedup = dedup;
zp->zp_dedup_verify = dedup && dedup_verify;
zp->zp_nopwrite = nopwrite;
zp->zp_encrypt = encrypt;
zp->zp_byteorder = ZFS_HOST_BYTEORDER;
bzero(zp->zp_salt, ZIO_DATA_SALT_LEN);
bzero(zp->zp_iv, ZIO_DATA_IV_LEN);
bzero(zp->zp_mac, ZIO_DATA_MAC_LEN);
zp->zp_zpl_smallblk = DMU_OT_IS_FILE(zp->zp_type) ?
os->os_zpl_special_smallblock : 0;
ASSERT3U(zp->zp_compress, !=, ZIO_COMPRESS_INHERIT);
}
/*
* This function is only called from zfs_holey_common() for zpl_llseek()
* in order to determine the location of holes. In order to accurately
* report holes all dirty data must be synced to disk. This causes extremely
* poor performance when seeking for holes in a dirty file. As a compromise,
* only provide hole data when the dnode is clean. When a dnode is dirty
* report the dnode as having no holes which is always a safe thing to do.
*/
int
dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
{
dnode_t *dn;
int i, err;
boolean_t clean = B_TRUE;
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
/*
* Check if dnode is dirty
*/
for (i = 0; i < TXG_SIZE; i++) {
if (multilist_link_active(&dn->dn_dirty_link[i])) {
clean = B_FALSE;
break;
}
}
/*
* If compatibility option is on, sync any current changes before
* we go trundling through the block pointers.
*/
if (!clean && zfs_dmu_offset_next_sync) {
clean = B_TRUE;
dnode_rele(dn, FTAG);
txg_wait_synced(dmu_objset_pool(os), 0);
err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
}
if (clean)
err = dnode_next_offset(dn,
(hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
else
err = SET_ERROR(EBUSY);
dnode_rele(dn, FTAG);
return (err);
}
void
__dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
{
dnode_phys_t *dnp = dn->dn_phys;
doi->doi_data_block_size = dn->dn_datablksz;
doi->doi_metadata_block_size = dn->dn_indblkshift ?
1ULL << dn->dn_indblkshift : 0;
doi->doi_type = dn->dn_type;
doi->doi_bonus_type = dn->dn_bonustype;
doi->doi_bonus_size = dn->dn_bonuslen;
doi->doi_dnodesize = dn->dn_num_slots << DNODE_SHIFT;
doi->doi_indirection = dn->dn_nlevels;
doi->doi_checksum = dn->dn_checksum;
doi->doi_compress = dn->dn_compress;
doi->doi_nblkptr = dn->dn_nblkptr;
doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
doi->doi_fill_count = 0;
for (int i = 0; i < dnp->dn_nblkptr; i++)
doi->doi_fill_count += BP_GET_FILL(&dnp->dn_blkptr[i]);
}
void
dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
{
rw_enter(&dn->dn_struct_rwlock, RW_READER);
mutex_enter(&dn->dn_mtx);
__dmu_object_info_from_dnode(dn, doi);
mutex_exit(&dn->dn_mtx);
rw_exit(&dn->dn_struct_rwlock);
}
/*
* Get information on a DMU object.
* If doi is NULL, just indicates whether the object exists.
*/
int
dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
{
dnode_t *dn;
int err = dnode_hold(os, object, FTAG, &dn);
if (err)
return (err);
if (doi != NULL)
dmu_object_info_from_dnode(dn, doi);
dnode_rele(dn, FTAG);
return (0);
}
/*
* As above, but faster; can be used when you have a held dbuf in hand.
*/
void
dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
DB_DNODE_ENTER(db);
dmu_object_info_from_dnode(DB_DNODE(db), doi);
DB_DNODE_EXIT(db);
}
/*
* Faster still when you only care about the size.
* This is specifically optimized for zfs_getattr().
*/
void
dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
u_longlong_t *nblk512)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
*blksize = dn->dn_datablksz;
/* add in number of slots used for the dnode itself */
*nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
SPA_MINBLOCKSHIFT) + dn->dn_num_slots;
DB_DNODE_EXIT(db);
}
void
dmu_object_dnsize_from_db(dmu_buf_t *db_fake, int *dnsize)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
*dnsize = dn->dn_num_slots << DNODE_SHIFT;
DB_DNODE_EXIT(db);
}
void
byteswap_uint64_array(void *vbuf, size_t size)
{
uint64_t *buf = vbuf;
size_t count = size >> 3;
int i;
ASSERT((size & 7) == 0);
for (i = 0; i < count; i++)
buf[i] = BSWAP_64(buf[i]);
}
void
byteswap_uint32_array(void *vbuf, size_t size)
{
uint32_t *buf = vbuf;
size_t count = size >> 2;
int i;
ASSERT((size & 3) == 0);
for (i = 0; i < count; i++)
buf[i] = BSWAP_32(buf[i]);
}
void
byteswap_uint16_array(void *vbuf, size_t size)
{
uint16_t *buf = vbuf;
size_t count = size >> 1;
int i;
ASSERT((size & 1) == 0);
for (i = 0; i < count; i++)
buf[i] = BSWAP_16(buf[i]);
}
/* ARGSUSED */
void
byteswap_uint8_array(void *vbuf, size_t size)
{
}
void
dmu_init(void)
{
abd_init();
zfs_dbgmsg_init();
sa_cache_init();
xuio_stat_init();
dmu_objset_init();
dnode_init();
zfetch_init();
dmu_tx_init();
l2arc_init();
arc_init();
dbuf_init();
}
void
dmu_fini(void)
{
arc_fini(); /* arc depends on l2arc, so arc must go first */
l2arc_fini();
dmu_tx_fini();
zfetch_fini();
dbuf_fini();
dnode_fini();
dmu_objset_fini();
xuio_stat_fini();
sa_cache_fini();
zfs_dbgmsg_fini();
abd_fini();
}
#if defined(_KERNEL)
EXPORT_SYMBOL(dmu_bonus_hold);
EXPORT_SYMBOL(dmu_bonus_hold_by_dnode);
EXPORT_SYMBOL(dmu_buf_hold_array_by_bonus);
EXPORT_SYMBOL(dmu_buf_rele_array);
EXPORT_SYMBOL(dmu_prefetch);
EXPORT_SYMBOL(dmu_free_range);
EXPORT_SYMBOL(dmu_free_long_range);
EXPORT_SYMBOL(dmu_free_long_object);
EXPORT_SYMBOL(dmu_read);
EXPORT_SYMBOL(dmu_read_by_dnode);
EXPORT_SYMBOL(dmu_write);
EXPORT_SYMBOL(dmu_write_by_dnode);
EXPORT_SYMBOL(dmu_prealloc);
EXPORT_SYMBOL(dmu_object_info);
EXPORT_SYMBOL(dmu_object_info_from_dnode);
EXPORT_SYMBOL(dmu_object_info_from_db);
EXPORT_SYMBOL(dmu_object_size_from_db);
EXPORT_SYMBOL(dmu_object_dnsize_from_db);
EXPORT_SYMBOL(dmu_object_set_nlevels);
EXPORT_SYMBOL(dmu_object_set_blocksize);
EXPORT_SYMBOL(dmu_object_set_maxblkid);
EXPORT_SYMBOL(dmu_object_set_checksum);
EXPORT_SYMBOL(dmu_object_set_compress);
EXPORT_SYMBOL(dmu_write_policy);
EXPORT_SYMBOL(dmu_sync);
EXPORT_SYMBOL(dmu_request_arcbuf);
EXPORT_SYMBOL(dmu_return_arcbuf);
EXPORT_SYMBOL(dmu_assign_arcbuf_by_dnode);
EXPORT_SYMBOL(dmu_assign_arcbuf_by_dbuf);
EXPORT_SYMBOL(dmu_buf_hold);
EXPORT_SYMBOL(dmu_ot);
/* BEGIN CSTYLED */
module_param(zfs_nopwrite_enabled, int, 0644);
MODULE_PARM_DESC(zfs_nopwrite_enabled, "Enable NOP writes");
module_param(zfs_per_txg_dirty_frees_percent, ulong, 0644);
MODULE_PARM_DESC(zfs_per_txg_dirty_frees_percent,
"percentage of dirtied blocks from frees in one TXG");
module_param(zfs_dmu_offset_next_sync, int, 0644);
MODULE_PARM_DESC(zfs_dmu_offset_next_sync,
"Enable forcing txg sync to find holes");
module_param(dmu_prefetch_max, int, 0644);
MODULE_PARM_DESC(dmu_prefetch_max,
"Limit one prefetch call to this size");
/* END CSTYLED */
#endif
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