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OpenZFS 8155 - simplify dmu_write_policy handling of pre-compressed b…
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…uffers

Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

When writing pre-compressed buffers, arc_write() requires that
the compression algorithm used to compress the buffer matches
the compression algorithm requested by the zio_prop_t, which is
set by dmu_write_policy(). This makes dmu_write_policy() and its
callers a bit more complicated.

We simplify this by making arc_write() trust the caller to supply
the type of pre-compressed buffer that it wants to write,
and override the compression setting in the zio_prop_t.

OpenZFS-issue: https://www.illumos.org/issues/8155
OpenZFS-commit: openzfs/openzfs@b55ff58
Closes openzfs#6200
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@ahrens @behlendorf
ahrens authored and behlendorf committed Jun 7, 2017
1 parent 4070bfd commit 8264410
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Showing 5 changed files with 18 additions and 26 deletions.
6 changes: 3 additions & 3 deletions include/sys/dmu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2011, 2016 by Delphix. All rights reserved.
* Copyright (c) 2011, 2017 by Delphix. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2012, Joyent, Inc. All rights reserved.
* Copyright 2014 HybridCluster. All rights reserved.
Expand Down Expand Up @@ -430,8 +430,8 @@ dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
#define WP_DMU_SYNC 0x2
#define WP_SPILL 0x4

void dmu_write_policy(objset_t *os, struct dnode *dn, int level, int wp,
enum zio_compress compress_override, struct zio_prop *zp);
void dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
struct zio_prop *zp);
/*
* The bonus data is accessed more or less like a regular buffer.
* You must dmu_bonus_hold() to get the buffer, which will give you a
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12 changes: 9 additions & 3 deletions module/zfs/arc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5977,6 +5977,7 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
arc_buf_hdr_t *hdr = buf->b_hdr;
arc_write_callback_t *callback;
zio_t *zio;
zio_prop_t localprop = *zp;

ASSERT3P(ready, !=, NULL);
ASSERT3P(done, !=, NULL);
Expand All @@ -5987,7 +5988,13 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
if (l2arc)
arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
if (ARC_BUF_COMPRESSED(buf)) {
ASSERT3U(zp->zp_compress, !=, ZIO_COMPRESS_OFF);
/*
* We're writing a pre-compressed buffer. Make the
* compression algorithm requested by the zio_prop_t match
* the pre-compressed buffer's compression algorithm.
*/
localprop.zp_compress = HDR_GET_COMPRESS(hdr);

ASSERT3U(HDR_GET_LSIZE(hdr), !=, arc_buf_size(buf));
zio_flags |= ZIO_FLAG_RAW;
}
Expand Down Expand Up @@ -6023,8 +6030,7 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,

zio = zio_write(pio, spa, txg, bp,
abd_get_from_buf(buf->b_data, HDR_GET_LSIZE(hdr)),
HDR_GET_LSIZE(hdr), arc_buf_size(buf), zp,
arc_write_ready,
HDR_GET_LSIZE(hdr), arc_buf_size(buf), &localprop, arc_write_ready,
(children_ready != NULL) ? arc_write_children_ready : NULL,
arc_write_physdone, arc_write_done, callback,
priority, zio_flags, zb);
Expand Down
4 changes: 1 addition & 3 deletions module/zfs/dbuf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3736,9 +3736,7 @@ dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
wp_flag = WP_SPILL;
wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;

dmu_write_policy(os, dn, db->db_level, wp_flag,
(data != NULL && arc_get_compression(data) != ZIO_COMPRESS_OFF) ?
arc_get_compression(data) : ZIO_COMPRESS_INHERIT, &zp);
dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
DB_DNODE_EXIT(db);

/*
Expand Down
20 changes: 4 additions & 16 deletions module/zfs/dmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2011, 2016 by Delphix. 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.
Expand Down Expand Up @@ -1705,8 +1705,7 @@ dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)

DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC,
ZIO_COMPRESS_INHERIT, &zp);
dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
DB_DNODE_EXIT(db);

/*
Expand Down Expand Up @@ -1876,8 +1875,7 @@ int zfs_mdcomp_disable = 0;
int zfs_redundant_metadata_most_ditto_level = 2;

void
dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
enum zio_compress override_compress, zio_prop_t *zp)
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) ||
Expand All @@ -1890,9 +1888,6 @@ dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
boolean_t dedup_verify = os->os_dedup_verify;
int copies = os->os_copies;

IMPLY(override_compress == ZIO_COMPRESS_LZ4,
spa_feature_is_active(os->os_spa, SPA_FEATURE_LZ4_COMPRESS));

/*
* We maintain different write policies for each of the following
* types of data:
Expand Down Expand Up @@ -1979,14 +1974,7 @@ dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
}

zp->zp_checksum = checksum;

/*
* If we're writing a pre-compressed buffer, the compression type we use
* must match the data. If it hasn't been compressed yet, then we should
* use the value dictated by the policies above.
*/
zp->zp_compress = override_compress != ZIO_COMPRESS_INHERIT
? override_compress : compress;
zp->zp_compress = compress;
ASSERT3U(zp->zp_compress, !=, ZIO_COMPRESS_INHERIT);

zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
Expand Down
2 changes: 1 addition & 1 deletion module/zfs/dmu_objset.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1326,7 +1326,7 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
arc_release(os->os_phys_buf, &os->os_phys_buf);

dmu_write_policy(os, NULL, 0, 0, ZIO_COMPRESS_INHERIT, &zp);
dmu_write_policy(os, NULL, 0, 0, &zp);

zio = arc_write(pio, os->os_spa, tx->tx_txg,
blkptr_copy, os->os_phys_buf, DMU_OS_IS_L2CACHEABLE(os),
Expand Down

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