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Raw receives must compress metadnode blocks

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Currently, the DMU relies on ZIO layer compression to free LO
dnode blocks that no longer have objects in them. However,
raw receives disable all compression, meaning that these blocks
can never be freed. In addition to the obvious space concerns,
this could also cause incremental raw receives to fail to mount
since the MAC of a hole is different from that of a completely
zeroed block.

This patch corrects this issue by adding a special case in
zio_write_compress() which will attempt to compress these blocks
to a hole even if ZIO_FLAG_RAW_ENCRYPT is set. This patch also
removes the zfs_mdcomp_disable tunable, since tuning it could
cause these same issues.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #7198
This commit is contained in:
Tom Caputi
2018-02-21 15:28:52 -05:00
committed by Brian Behlendorf
parent 5121c4fb0c
commit b1d217338a
7 changed files with 24 additions and 41 deletions
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module/zfs/dmu.c
+6 -15
View File
@@ -2107,8 +2107,6 @@ dmu_object_dirty_raw(objset_t *os, uint64_t object, dmu_tx_t *tx)
return (err);
}
int zfs_mdcomp_disable = 0;
/*
* When the "redundant_metadata" property is set to "most", only indirect
* blocks of this level and higher will have an additional ditto block.
@@ -2138,16 +2136,12 @@ dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
* 3. all other level 0 blocks
*/
if (ismd) {
if (zfs_mdcomp_disable) {
compress = ZIO_COMPRESS_EMPTY;
} else {
/*
* 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);
}
/*
* 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
@@ -2523,9 +2517,6 @@ EXPORT_SYMBOL(dmu_buf_hold);
EXPORT_SYMBOL(dmu_ot);
/* BEGIN CSTYLED */
module_param(zfs_mdcomp_disable, int, 0644);
MODULE_PARM_DESC(zfs_mdcomp_disable, "Disable meta data compression");
module_param(zfs_nopwrite_enabled, int, 0644);
MODULE_PARM_DESC(zfs_nopwrite_enabled, "Enable NOP writes");